@article{wu_tan_pietrafesa_2023, title={Spectral analysis of a time series: From an additive perspective to a multiplicative perspective}, volume={63}, ISSN={["1096-603X"]}, DOI={10.1016/j.acha.2022.11.005}, abstractNote={The study of trigonometric functions traces back to Hellenistic mathematicians such as Pythagoras, Euclid, and Archimedes. Many fundamental methods of analysis use trigonometric functions to describe and understand cyclical phenomena. It was Fourier in the early years of the 19th century who pioneered the additive usage of trigonometric functions and first expressed various types of functions in terms of the sum of constant-amplitude constant-frequency trigonometric functions of different periods, now called the Fourier Transform. Unfortunately, Fourier's sum does not explicitly express nonlinear interactions between trigonometric components of different periods. To seek a remedy, a multiplicative perspective of using trigonometric functions in quantifying nonlinear interaction in any time series has been developed, starting with the invention of the Empirical Mode Decomposition methodology in the late 1990s by Norden E Huang. The most recent development is a multi-dimensional spectral representation of a time series, which is termed in this paper as the Huang Spectrum. Huang Spectral Analysis explicitly identifies the interactions among time-varying amplitude and frequency oscillatory components of different periods of a time series and quantifies nonlinear interactions explicitly. This paper introduces the intuitions and physical rationales behind the Huang Spectrum and Huang Spectral Analysis. Various synthetic and climatic time series with known time series characteristics are used to demonstrate the power of Huang Spectral Analysis.}, journal={APPLIED AND COMPUTATIONAL HARMONIC ANALYSIS}, author={Wu, Zhaohua and Tan, Zhe-Min and Pietrafesa, Leonard}, year={2023}, month={Mar}, pages={94–112} }
 @article{shen_bao_pietrafesa_gayes_2022, title={Improving Numerical Model Predicted Float Trajectories by Deep Learning}, volume={9}, ISSN={["2333-5084"]}, DOI={10.1029/2022EA002362}, abstractNote={Abstract}, number={9}, journal={EARTH AND SPACE SCIENCE}, author={Shen, Dongliang and Bao, Shaowu and Pietrafesa, Lenard J. and Gayes, Paul}, year={2022}, month={Sep} }
 @article{zhang_shen_bao_pietrafesa_gayes_majidzadeh_2022, title={Quantifying Aggravated Threats to Stormwater Management Ponds by Tropical Cyclone Storm Surge and Inundation under Climate Change Scenarios}, volume={10}, ISSN={["2225-1154"]}, DOI={10.3390/cli10100157}, abstractNote={Stormwater management ponds (SMPs) protect coastal communities from flooding caused by heavy rainfall and runoff. If the SMPs are submerged under seawater during a tropical cyclone (TC) and its storm surge, their function will be compromised. Under climate change scenarios, this threat is exacerbated by sea level rise (SLR) and more extreme tropical cyclones. This study quantifies the impact of tropical cyclones and their storm surge and inundation on South Carolina SMPs under various SLR scenarios. A coupled hydrodynamic model calculates storm surge heights and their return periods using historical tropical cyclones. The surge decay coefficient method is used to calculate inundation areas caused by different return period storm surges under various SLR scenarios. According to the findings, stormwater management ponds will be aggravated by sea level rise and extreme storm surge. In South Carolina, the number of SMPs at risk of being inundated by tides and storm surges increases almost linearly with SLR, by 10 SMPs for every inch of SLR for TC storm surges with all return periods. Long Bay, Charleston, and Beaufort were identified as high-risk coastal areas. The findings of this study indicate where current SMPs need to be redesigned and where more SMPs are required. The modeling and analysis system used in this study can be employed to evaluate the effects of SLR and other types of climate change on SMP facilities in other regions.}, number={10}, journal={CLIMATE}, author={Zhang, Hongyuan and Shen, Dongliang and Bao, Shaowu and Pietrafesa, Leonard and Gayes, Paul T. and Majidzadeh, Hamed}, year={2022}, month={Oct} }
 @article{shen_li_wang_bao_pietrafesa_2021, title={Dynamical Ocean Responses to Typhoon Malakas (2016) in the Vicinity of Taiwan}, volume={126}, ISSN={["2169-9291"]}, DOI={10.1029/2020JC016663}, abstractNote={Abstract}, number={2}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS}, author={Shen, Dongliang and Li, Xiaofeng and Wang, Jia and Bao, Shaowu and Pietrafesa, Leonard J.}, year={2021}, month={Feb} }
 @article{viner_noble_qian_werth_gayes_pietrafesa_bao_2021, title={Frequency and Characteristics of Inland Advecting Sea Breezes in the Southeast United States}, volume={12}, ISSN={["2073-4433"]}, DOI={10.3390/atmos12080950}, abstractNote={Sea breezes have been observed to move inland over 100 km. These airmasses can be markedly different from regional airmasses, creating a shallow layer with differences in humidity, wind, temperature and aerosol characteristics. To understand their influence on boundary layer and cloud development on subsequent days, we identify their frequency and characteristics. We visually identified sea breeze fronts on radar passing over the Savannah River Site (SRS) between March and October during 2015–2019. The SRS is ~150 km from the nearest coastal location; therefore, our detection suggests further inland penetration. We also identified periods when sea breeze fronts may have passed but were not visually observed on radar due to the shallow sea breeze airmass remaining below the radar beam elevation that ranges between approximately 1–8 km depending on the beam angle and radar source (Columbia, SC or Charleston, SC). Near-surface atmospheric measurements indicate that the dew point temperature increases, the air temperature decreases, the variation in wind direction decreases and the aerosol size increases after sea breeze frontal passage. A synoptic classification procedure also identified that inland moving sea breezes are more commonly observed when the synoptic conditions include weak to moderate offshore winds with an average of 35 inland sea breezes occurring each year, focused primarily in the months of April, May and June.}, number={8}, journal={ATMOSPHERE}, author={Viner, Brian and Noble, Stephen and Qian, Jian-Hua and Werth, David and Gayes, Paul and Pietrafesa, Len and Bao, Shaowu}, year={2021}, month={Aug} }
 @article{pietrafesa_zhang_bao_gayes_hallstrom_2019, title={Coastal Flooding and Inundation and Inland Flooding due to Downstream Blocking}, volume={7}, ISSN={["2077-1312"]}, DOI={10.3390/jmse7100336}, abstractNote={Extreme atmospheric wind and precipitation events have created extensive multiscale coastal, inland, and upland flooding in United States (U.S.) coastal states over recent decades, some of which takes days to hours to develop, while others can take only several tens of minutes and inundate a large area within a short period of time, thus being laterally explosive. However, their existence has not yet been fully recognized, and the fluid dynamics and the wide spectrum of spatial and temporal scales of these types of events are not yet well understood nor have they been mathematically modeled. If present-day outlooks of more frequent and intense precipitation events in the future are accurate, these coastal, inland and upland flood events, such as those due to Hurricanes Joaquin (2015), Matthew (2016), Harvey (2017) and Irma (2017), will continue to increase in the future. However, the question arises as to whether there has been a well-documented example of this kind of coastal, inland and upland flooding in the past? In addition, if so, are any lessons learned for the future? The short answer is “no”. Fortunately, there are data from a pair of events, several decades ago—Hurricanes Dennis and Floyd in 1999—that we can turn to for guidance in how the nonlinear, multiscale fluid physics of these types of compound hazard events manifested in the past and what they portend for the future. It is of note that fifty-six lives were lost in coastal North Carolina alone from this pair of storms. In this study, the 1999 rapid coastal and inland flooding event attributed to those two consecutive hurricanes is documented and the series of physical processes and their mechanisms are analyzed. A diagnostic assessment using data and numerical models reveals the physical mechanisms of downstream blocking that occurred.}, number={10}, journal={JOURNAL OF MARINE SCIENCE AND ENGINEERING}, author={Pietrafesa, Leonard J. and Zhang, Hongyuan and Bao, Shaowu and Gayes, Paul T. and Hallstrom, Jason O.}, year={2019}, month={Oct} }
 @article{li_zheng_yang_pietrafesa_2017, title={Sea Fetch Observed by Synthetic Aperture Radar}, volume={55}, ISSN={["1558-0644"]}, DOI={10.1109/tgrs.2016.2605670}, abstractNote={Two satellite synthetic aperture radar (SAR) observations of the fetch in the Bohai Sea of China are presented. The sea surface winds derived from SAR data indicated a high wind of 15-16 m/s that occurred in the fetch zone. The winds are shown to have immediate direct mechanical forcing impacts on the significant wave heights (Hs) of ocean surface gravity waves. Buoy measurements and numerical wave modeling results show that the Hs increased to a maximum of 3.5 m in the semienclosed sea, 3 h after the passage of the fetch winds, and the high Hs in the sea was sustained for a total of 6 h. The Weather Research and Forecasting (WRF) model implemented in our modeling simulation captured the wind field responsible for the evolution of the fetch event. The model-simulated surface horizontal winds agree with the SAR-derived winds. In addition, the vertical wind distribution reveals that the fetch wind field reached the 800 hPa level, and the event lasted less than one day. This study demonstrates the synergy of using SAR imagery and the WRF model as effective tools to investigate the lateral and vertical structures of coastal wind.}, number={1}, journal={IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING}, author={Li, Xiaofeng and Zheng, Weizhong and Yang, Xiaofeng and Pietrafesa, Leonard J.}, year={2017}, month={Jan}, pages={272–279} }
 @article{xu_li_bao_pietrafesa_2016, title={SAR Observation and Numerical Simulation of Mountain Lee Waves Near Kuril Islands Forced by an Extratropical Cyclone}, volume={54}, ISSN={["1558-0644"]}, DOI={10.1109/tgrs.2016.2596678}, abstractNote={Several groups of atmospheric gravity waves (AGWs) were observed on a Sentinel-1A synthetic aperture radar (SAR) image acquired near the Kuril Islands in the Northwest Pacific Ocean on June 1, 2015 during the passage of an extratropical cyclone (ETC). These waves occurred on the lee side of the mountains located on the islands. Both diverging and transverse waves with wavelengths ranging between 20 and 30 km are shown as alternating bright-dark patterns in the SAR image. For the diverging waves, there exists a prominent asymmetry in the wave motions of the two arms. The Moderate Resolution Imaging Spectroradiometer and Landsat 7 Enhanced Thematic Mapper Plus images acquired 5-7 h prior to the Sentinel-1A pass also contain the same groups of AGWs. The mesoscale Weather Research and Forecasting model simulation confirms that the AGWs are lee waves triggered by the airflow over the islands. AGWs are aligned perpendicular to the wind direction and locked on the lee side of the islands. The life span of the waves is about two days, consistent with that of the ETC over the region. The numerical model also successfully reproduces the main characteristics of the lee waves. Simulation results demonstrate that the variation in the wave parameters (i.e., wavelength, amplitude, orientation, wedge angle of the diverging wave, and vertical propagation characteristic) and the wave asymmetry of the diverging wave are mainly caused by the wind and stratification changes. The smaller amplitude of the diverging wave seems to be associated with a smaller Froude number.}, number={12}, journal={IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING}, author={Xu, Qing and Li, Xiaofeng and Bao, Shaowu and Pietrafesa, Leonard J.}, year={2016}, month={Dec}, pages={7157–7165} }
 @article{xia_xie_pietrafesa_whitney_2011, title={The ideal response of a Gulf of Mexico estuary plume to wind forcing: Its connection with salt flux and a Lagrangian view}, volume={116}, ISSN={["2169-9291"]}, DOI={10.1029/2010jc006689}, abstractNote={[1] The plume structure of Perdido Bay Estuary (PBE), a typical bay on the Florida-Alabama coast along the Gulf of Mexico, was simulated using an existing calibrated model. To better understand plume dynamics in the PBE and similar bay systems, idealized sensitivity experiments were conducted to examine the influence of wind stress on the 3-D plume signature: the results indicate that wind speed and direction significantly influence plume orientation, area, width, length, and depth. The plume size was reduced under the effect of wind and increased wind forcing. Among wind-forced cases, the plume is largest for northerly (offshore) winds and smallest for southerly (onshore) winds. Bay-shelf salt flux and water flux were also investigated, since they are important for the formation of a 3-D plume structure. Model simulations show that water outflow to the coastal ocean is strongest under northerly winds and can be stopped by southerly winds. For moderately strong winds, the outflow and plume size are larger for easterly downwelling-favorable winds than for westerly upwelling-favorable winds; the opposite is true for outflow and plume size for these two wind directions under stronger winds. For all wind directions, the ratio of salt flux and water flux at the bay mouth increases with wind speed. This ratio trend is consistent with higher outflow salinities, and this decreased buoyancy signature, along with more energetic vertical mixing, reduces plume size. A detailed understanding of this water and salt flux is essential to the plume dynamics studied here and for other plumes. Additional particle transport analysis using variable wind forcing was conducted to determine the influence of the plume on particle movement. The results showed a consistency between the surface plume, salt flux, and particle transport and illustrate the strong effects that winds have on particle fate and dispersion.}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS}, author={Xia, Meng and Xie, Lian and Pietrafesa, Leonard J. and Whitney, Michael M.}, year={2011}, month={Aug} }
 @article{li_yang_zheng_pietrafesa_pichel_li_li_2010, title={Deep-water bathymetric features imaged by spaceborne SAR in the Gulf Stream region}, volume={37}, ISSN={["1944-8007"]}, DOI={10.1029/2010gl044406}, abstractNote={Deep‐water (>500 m) oceanic bathymetric features are frequently observed in RADARSAT‐1 SAR images in the Gulf Stream (GS) region. They are imaged apparently because of the unique environmental conditions in the region, oceanographically characterized by a strong GS current (2 ms−1) and favorable ocean stratification. SAR image analysis shows the basic characteristics of these bathymetric features. A coincident sea surface temperature image shows that the bathymetric feature is only “visible” by SAR within the GS pathway. The dominant wavelength of the wave‐like feature is about 2.3 km and their crests are perpendicular to the GS axis. Shipboard sounding measurements confirm the SAR observation. A theoretical consideration of the ocean current and corrugated bathymetry interaction in a 3‐layer ocean is presented. Using representative ocean density profile data and the GS current data, we analyze the requirements for the generation and upward propagation of the disturbance induced by the current‐bathymetry interaction.}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Li, Xiaofeng and Yang, Xiaofeng and Zheng, Quanan and Pietrafesa, Leonard J. and Pichel, William G. and Li, Ziwei and Li, Xiaoming}, year={2010}, month={Oct} }
 @article{xia_xie_pietrafesa_2010, title={Winds and the orientation of a coastal plane estuary plume}, volume={37}, ISSN={["0094-8276"]}, DOI={10.1029/2010gl044494}, abstractNote={Based on a calibrated coastal plane estuary plume model, ideal model hindcasts of estuary plumes are used to describe the evolution of the plume pattern in response to river discharge and local wind forcing by selecting a typical partially mixed estuary (the Cape Fear River Estuary or CFRE). With the help of an existing calibrated plume model, as described by Xia et al. (2007), simulations were conducted using different parameters to evaluate the plume behavior type and its change associated with the variation of wind forcing and river discharge. The simulations indicate that relatively moderate winds can mechanically reverse the flow direction of the plume. Downwelling favorably wind will pin the plume to the coasts while the upwelling plume could induce plume from the left side to right side in the application to CFRE. It was found that six major types of plumes may occur in the estuary and in the corresponding coastal ocean. To better understand these plumes in the CFRE and other similar river estuary systems, we also investigated how the plumes transition from one type to another. Results showed that wind direction, wind speed, and sometimes river discharge contribute to plume transitions.}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Xia, Meng and Xie, Lian and Pietrafesa, Leonard J.}, year={2010}, month={Oct} }
 @article{taylor_miller_pietrafesa_dickey_ross_2010, title={Winter winds and river discharge determine juvenile southern flounder (Paralichthys lethostigma) recruitment and distribution in North Carolina estuaries}, volume={64}, ISSN={["1873-1414"]}, DOI={10.1016/j.seares.2009.09.006}, abstractNote={Retrospective analyses of a 23 year data set on abundance of Age 0 southern flounder in 105 estuarine nursery areas in the coastal region of North Carolina showed that discernible temporal and spatial patterns exist among clusters of stations. Furthermore, these patterns could be quantitatively related to certain meteorological and hydrological variables, namely winds from the east–southeast (E–SE) and from the north–northeast (N–NE) sectors and river runoff, which explained up to 83% of the interannual variability in numbers. We developed a regression model using recent catch data (1987–2002) and used the model to hindcast an earlier segment of the time series (1979–1986). The model was found to be quite robust, and could predict year class strength within 1 to 80% in the test set of data. We interpret these results to mean that hydrodynamic factors are principally responsible for the observed interannual recruitment variability in southern flounder in NC, since the interannual pattern in abundance of Age 0 fish persists for 2 more years of adult life. Finally, we discuss the implications of the variable spatial distribution patterns for estimates of year class strength from juvenile abundance data. It is possible that estimates of year class strength with a useful level of confidence could be obtained from meteorological data during the larval migration period.}, number={1-2}, journal={JOURNAL OF SEA RESEARCH}, author={Taylor, J. Christopher and Miller, John M. and Pietrafesa, Leonard J. and Dickey, David A. and Ross, Steve W.}, year={2010}, pages={15–25} }
 @article{wright_walsh_krabill_shaffer_baig_peng_pietrafesa_garcia_marks_black_et al._2009, title={Measuring Storm Surge with an Airborne Wide-Swath Radar Altimeter}, volume={26}, ISSN={["1520-0426"]}, DOI={10.1175/2009JTECHO627.1}, abstractNote={Abstract}, number={10}, journal={JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY}, author={Wright, C. W. and Walsh, E. J. and Krabill, W. B. and Shaffer, W. A. and Baig, S. R. and Peng, M. and Pietrafesa, L. J. and Garcia, A. W. and Marks, F. D., Jr. and Black, P. G. and et al.}, year={2009}, month={Oct}, pages={2200–2215} }
 @article{xia_xie_pietrafesa_peng_2008, title={A numerical study of storm surge in the Cape Fear River Estuary and adjacent coast}, volume={24}, ISSN={["1551-5036"]}, DOI={10.2112/06-0795.1}, abstractNote={Abstract The Cape Fear River Estuary (CFRE) region is a coastal domain that has experienced considerable threats and impacts from tropical cyclones. It is also an important nursery for juvenile fish, crabs, shrimp, and other biological species. Thus, predictions about the physical responses of the CFRE system to extreme weather events are important to the protection of life and property and to the economical well-being of local residents. In this study, the Princeton Ocean Model (POM) is used to simulate tropical cyclone storm–induced surge, inundation, and coastal circulation in the CFRE and the adjacent Long Bay using a three-level nesting approach. Hindcasts of the hydrodynamic responses of the CFRE system to historic events were performed for Hurricanes Fran, Floyd, Bertha, and Charley. Comparisons were also made for the modeling results and the observations.}, number={4C}, journal={JOURNAL OF COASTAL RESEARCH}, author={Xia, Meng and Xie, Lian and Pietrafesa, Leonard J. and Peng, Machuan}, year={2008}, pages={159–167} }
 @article{lin_xie_pietrafesa_xu_woods_mallin_durako_2008, title={Water quality responses to simulated flow and nutrient reductions in the Cape Fear River Estuary and adjacent coastal region, North Carolina}, volume={212}, ISSN={["1872-7026"]}, DOI={10.1016/j.ecolmodel.2007.10.026}, abstractNote={In order to examine system responses to high river discharge events and nutrient loading variations from the drainage basin, a coupled three-dimensional hydrodynamic and water quality model was applied in the Cape Fear River Estuary (CFRE) and its adjacent coastal region. An empirical equation was introduced in the model to represent light limitation for phytoplankton growth due to chromophoric dissolved organic matter (CDOM). Model results show that in the upper to middle estuary, light limitation controls phytoplankton growth while in the lower estuary phytoplankton growth appears to be limited by light intensity during high flow periods, but by nutrient availability during low flow periods. In the coastal ocean, nutrient availability is usually the dominant limiting factor for primary production. Two sensitivity model tests were conducted to predict the system response to reductions in nutrient loading from the drainage basin. By reducing river discharge, the model results show that phytoplankton growth was enhanced within CFRE due to alleviated light limitation and increased residence time. More nutrients were consumed within the CFRE, and less were exported to the coastal region. By reducing nutrient concentrations at the head of the estuary, chlorophyll a concentrations within the CFRE were decreased. Less nutrients were consumed within the CFRE, and only slightly less were exported to the coastal region. The supply of light limiting substances during high flow events acted against the effect of riverine nutrient enhancement on phytoplankton growth, creating a negative feedback mechanism.}, number={3-4}, journal={ECOLOGICAL MODELLING}, author={Lin, Jing and Xie, Lian and Pietrafesa, Leonard J. and Xu, Honqzhou and Woods, Wendy and Mallin, Michael A. and Durako, Michael J.}, year={2008}, month={Apr}, pages={200–217} }
 @article{peng_xie_pietrafesa_2007, title={Correcting the errors in the initial conditions and wind stress in storm surge simulation using an adjoint optimal technique}, volume={18}, DOI={10.1016/j.ocemod.2007.04.002}, abstractNote={An adjoint data assimilation methodology is applied to the Princeton Ocean Model and is evaluated by obtaining “optimal” initial conditions, sea surface forcing conditions, or both for coastal storm surge modelling. By prescribing different error sources and setting the corresponding control variables, we performed several sets of identical twin experiments by assimilating model-generated water levels. The experiment results show that, when the forecasting errors are caused by the initial (or surface boundary) conditions, adjusting initial (or surface boundary) conditions accordingly can significantly improve the storm surge simulation. However, when the forecasting errors are caused by surface boundary (or initial) conditions, data assimilation targeting improving the initial (or surface boundary) conditions is ineffective. When the forecasting errors are caused by both the initial and surface boundary conditions, adjusting both the initial and surface boundary conditions leads to the best results. In practice, we do not know whether the errors are caused by initial conditions or surface boundary conditions, therefore it is better to adjust both initial and surface boundary conditions in adjoint data assimilation.}, number={3-4}, journal={Ocean Modelling (Oxford, England)}, author={Peng, S. Q. and Xie, L. and Pietrafesa, L. J.}, year={2007}, pages={175–193} }
 @article{xie_liu_pietrafesa_2007, title={Effect of bathymetric curvature on gulf stream instability in the vicinity of the Charleston Bump}, volume={37}, ISSN={["0022-3670"]}, DOI={10.1175/JPO2995.1}, abstractNote={Abstract}, number={3}, journal={JOURNAL OF PHYSICAL OCEANOGRAPHY}, author={Xie, Lian and Liu, Xiaoming and Pietrafesa, Leonard J.}, year={2007}, month={Mar}, pages={452–475} }
 @article{xia_xie_pietrafesa_2007, title={Modeling of the Cape Fear River Estuary plume}, volume={30}, ISSN={["1559-2731"]}, DOI={10.1007/BF02841966}, number={4}, journal={ESTUARIES AND COASTS}, author={Xia, Meng and Xie, Lian and Pietrafesa, Leonard J.}, year={2007}, month={Aug}, pages={698–709} }
 @article{pietrafesa_buckley_peng_bao_liu_peng_xie_dickey_2007, title={On coastal ocean systems, coupled model architectures, products and services: Morphing from observations to operations and applications}, volume={41}, ISSN={["1948-1209"]}, DOI={10.4031/002533207787442268}, abstractNote={The national build-up of “coastal ocean observing systems” (COOSs) to establish the coastal observing component of the national component of the Integrated Ocean Observing System (IOOS) network must be well organized and must acknowledge, understand and address the needs
 of the principal clients, the federal, and in some cases state as well, agencies that provide financial support if it is to have substantive value. The funds being spent in support of COOS should be invested in pursuit of the establishment of the National Backbone (NB) that is needed: to greatly
 improve atmospheric, oceanic and coastal “weather” forecasting, broadly defined; for ecosystem management; and to document climate variability and change in coastal zones. However, this process has not occurred in a well conceived, orderly, well integrated manner due to historical
 and cultural bases and because of local priorities. A sub-regional effort that is designed to meet federal agency needs and mission responsibilities with an emphasis on meeting societal needs is presented by way of example to show that university and industry partners with federal agencies
 have an important role to play in the future of building out ocean and coastal observing and prediction systems and networks.}, number={1}, journal={MARINE TECHNOLOGY SOCIETY JOURNAL}, author={Pietrafesa, L. J. and Buckley, E. B. and Peng, M. and Bao, S. and Liu, H. and Peng, S. and Xie, L. and Dickey, D. A.}, year={2007}, pages={44–52} }
 @article{liu_xie_pietrafesa_bao_2007, title={Sensitivity of wind waves to hurricane wind characteristics}, volume={18}, ISSN={["1463-5003"]}, DOI={10.1016/j.ocemod.2007.03.004}, abstractNote={In this study, the influence of the spatial and temporal variability of hurricane winds, storm translation speed, intensity, and ambient wind field on surface wind waves are investigated by using a third-generation wave model (Simulating WAves Nearshore, or SWAN). The results show that the asymmetric structure of wind-induced wave field is sensitive not only to the asymmetric structure of the hurricane wind field, but also to the variations in the storm translation speed and intensity. The significant wave height (SWH) in the front-right quadrant of the storm rises as storm translation speed increases until it reaches a critical value, then the SWH drops. The opposite occurs in the rear-left quadrant. The total contribution of the hurricane translation speed to the asymmetric structure of the wave field also depends on the intensity of the hurricane. As the intensity of the hurricane increases, the relative significance of the influence of the translation speed on the asymmetric structure of the wave field decreases. Most parametric hurricane wind models can only model symmetric hurricanes and do not include background winds. However, actual hurricanes in nature are not only asymmetric but also imbedded in background winds. Thus, to more properly model hurricane-induced wave field, it is important to consider storm asymmetry, translation speed, intensity, as well as background winds.}, number={1}, journal={OCEAN MODELLING}, author={Liu, Huiqing and Xie, Lian and Pietrafesa, Leonard J. and Bao, Shaowu}, year={2007}, pages={37–52} }
 @article{lin_xie_pietrafesa_ramus_paerl_2007, title={Water quality gradients across Albemarle-Pamlico estuarine system: Seasonal variations and model applications}, volume={23}, ISSN={["1551-5036"]}, DOI={10.2112/05-0507.1}, abstractNote={Abstract The seasonal variations of water quality parameters as nitrite plus nitrate (NO−;x), total phosphate (PO3−4), chlorophyll a (chl a), and dissolved oxygen (DO) are analyzed across the Croatan-Roanoke-Albemarle-Pamlico-Core Sounds estuarine system (CAPES). Overall, several patterns are observed: The Chowan-Roanoke-Albemarle system is generally phosphorous limiting for phytoplankton growth, whereas both the Tar-Pamlico and the Neuse Rivers are generally nitrogen limiting. The largest PO3−4 gradients exist in the upstream portion of the Albemarle Sound, and the largest NO−x gradients exist in the lower Neuse and the Tar-Pamlico Rivers. Dissolved oxygen appears to have the strongest seasonal signal among the water quality variables, with highest DO values observed during winter (within the CAPES and in the nearshore area) or spring (in the continental shelf and deeper ocean) and lowest during summer. Chlorophyll a concentrations are highest during spring (within the CAPES) or winter (offshore). In contrast, the NOx− and PO3−4 concentrations in both the Tar-Pamlico and Neuse River estuaries are usually higher during the second half of the year. The time differences of the peak nutrient and chl a concentrations suggest that highest algal growth rate (and hence nutrient uptake rate) occurs during spring, and the consumed nutrients are released to the water column through a nutrient recycling method later in the year. A coupled three-dimensional hydrodynamic water quality model is then applied to the entire system. The general model setup and parameter derivation of the model is presented here. The basic observed water quality characteristics such as the nutrient limiting pattern and the spatial gradients across the system are reproduced in the model. The model results also suggest that nutrient fluxes, generated from the diagenesis of deposited organic matter and released from the sediment bed, could be an important mechanism for nutrient recycling in the region.}, number={1}, journal={JOURNAL OF COASTAL RESEARCH}, author={Lin, Jing and Xie, Lian and Pietrafesa, Leonard J. and Ramus, Joseph S. and Paerl, Hans W.}, year={2007}, month={Jan}, pages={213–229} }
 @article{pietrafesa_kelleher_karl_davidson_peng_bao_dickey_xie_liu_xia_2006, title={A new architecture for coastal inundation and flood warning prediction}, volume={40}, ISSN={["0025-3324"]}, DOI={10.4031/002533206787353205}, abstractNote={The marine atmosphere, coastal ocean, estuary, harbor and river water systems constitute a physically coupled system. While these systems have always been heavily impacted by coastal storms, increases in population density, infrastructure, and personal and business merchandise have
 exacerbated the economic and personal impacts of these events over the past half century. As such there has been increased focus on the need for more timely and accurate forecasts of impending events. Traditionally model forecast architectures for coastal storm surge, flooding and inundation
 of coastal and inland areas have taken the approach of dealing with each system separately: rivers, estuaries, harbors and offshore facing areas. However, given advances in coupled modeling and the availability of real-time data, the ability to accurately predict and project coastal, estuary
 and inland flooding related to the passage of high energy and wet atmospheric events is rapidly emerging and requires a new paradigm in system architecture. No longer do monthly averaged winds or river discharge or water levels have to be invoked in developing hindcasts for planning purposes
 or for real-time forecasts. In 1999 a hurricane associated flood on the North Carolina coast took 56 lives and caused more than $6 billion in economic impacts. None of the models existing at that time were able to properly forecast the massive flooding and clearly called for a new model
 paradigm. Here we propose a model system that couples atmospheric information to fully three dimensional, non-linear time dependent ocean basin, coastal and estuary hydrodynamic models coupled to interactive river models with input of real or modeled winds, observed or modeled precipitation,
 measured and modeled water levels, and streamflow. The river and estuarine components must both be capable of going into modes of storage or accelerated discharge. Spatial scales must downscale in the horizontal from thousands to tens meters and in the vertical from hundreds to several centimeters.
 Topography and elevation data should be of the highest resolution available, necessary for highly accurate predictions of the timing and location of the inundation and retreat of flood waters. Precipitation information must be derived from the optimal mix of direct radar, satellite and ground-based
 observations. Creating the capability described above will advance the modernization of hydrologic services provided by the National Oceanic & Atmospheric Administration and provide more accurate and timely forecasts and climatologies of coastal and estuary flooding. The goal of these
 climatologies and improved forecasts is to provide better information to local and regional planners, emergency managers, highway patrols and to improve the capacity of coastal communities to mitigate against the impacts of coastal flooding.}, number={4}, journal={MARINE TECHNOLOGY SOCIETY JOURNAL}, author={Pietrafesa, L. J. and Kelleher, K. and Karl, T. and Davidson, M. and Peng, M. and Bao, S. and Dickey, D. and Xie, L. and Liu, H. and Xia, M.}, year={2006}, pages={71–77} }
 @article{peng_xie_pietrafesa_2006, title={A numerical study on hurricane-induced storm surge and inundation in Charleston Harbor, South Carolina}, volume={111}, ISSN={["2169-9291"]}, DOI={10.1029/2004jc002755}, abstractNote={A storm surge and inundation model is configured in Charleston Harbor and its adjacent coastal region to study the harbor's response to hurricanes. The hydrodynamic component of the modeling system is based on the Princeton Ocean Model, and a scheme with multiple inundation speed options is imbedded in the model for the inundation calculation. Historic observations (Hurricane Hugo and its related storm surge and inundation) in the Charleston Harbor region indicate that among three possible inundation speeds in the model, taking Ct (gd)1/2 (Ct is a terrain‐related parameter) as the inundation speed is the best choice. Choosing a different inundation speed in the model has effects not only on inundation area but also on storm surge height. A nesting technique is necessary for the model system to capture the mesoscale feature of a hurricane and meanwhile to maintain a higher horizontal resolution in the harbor region, where details of the storm surge and inundation are required. Hurricane‐induced storm surge and inundation are very sensitive to storm tracks. Twelve hurricanes with different tracks are simulated to investigate how Charleston Harbor might respond to tracks that are parallel or perpendicular to the coastline or landfall at Charleston at different angles. Experiments show that large differences of storm surge and inundation may have occurred if Hurricane Hugo had approached Charleston Harbor with a slightly different angle. A hurricane's central pressure, radius of maximum wind, and translation speed have their own complicated effects on surge and inundation when the hurricane approaches the coast on different tracks. Systematic experiments are performed in order to illustrate how each of such factors, or a combination of them, may affect the storm surge height and inundation area in the Charleston Harbor region. Finally, suggestions are given on how this numerical model system may be used for hurricane‐induced storm surge and inundation forecasting.}, number={C8}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS}, author={Peng, Machuan and Xie, Lian and Pietrafesa, Leonard J.}, year={2006}, month={Aug} }
 @article{xie_bao_pietrafesa_foley_fuentes_2006, title={A real-time hurricane surface wind forecasting model: Formulation and verification}, volume={134}, ISSN={["0027-0644"]}, DOI={10.1175/MWR3126.1}, abstractNote={Abstract}, number={5}, journal={MONTHLY WEATHER REVIEW}, author={Xie, L and Bao, SW and Pietrafesa, LJ and Foley, K and Fuentes, M}, year={2006}, month={May}, pages={1355–1370} }
 @misc{pietrafesa_2006, title={Concern about gag rules}, volume={312}, DOI={10.1126/science.312.5777.1137d}, abstractNote={With regard to Donald Kennedy's Editorial “The new gag rules” (17 Feb., p. [917][1]), the National Oceanic and Atmospheric Administration's (NOAA) Science Advisory Board (SAB) is deeply concerned about reports of attempts to suppress and/or distort the reporting or representation of scientific}, number={5777}, journal={Science}, author={Pietrafesa, L.}, year={2006}, pages={1137–1138} }
 @misc{boehm_hopkins_pietrafesa_churchill_2006, title={Continental slope sea level and flow variability induced by lateral movements of the Gulf Stream in the Middle Atlantic Bight}, volume={70}, ISSN={["0079-6611"]}, DOI={10.1016/j.pocean.2006.07.005}, abstractNote={Abstract As described by [Csanady, G.T., Hamilton, P., 1988. Circulation of slope water. Continental Shelf Research 8, 565–624], the flow regime over the slope of the southern Middle Atlantic Bight (MAB) includes a current reversal in which southwestward flow over the upper and middle slope becomes entrained in the northeastward current adjacent to the Gulf Stream. In this paper we use satellite-derived data to quantify how lateral motions of the Gulf Stream impact this current system. In our analysis, the Gulf Stream’s thermal front is delineated using a two-year time series of sea surface temperature derived from NOAA/AVHRR satellite data. Lateral motions of the Gulf Stream are represented in terms of temporal variations of the area, east of 73°W, between the Gulf Stream thermal front and the shelf edge. Variations of slope water flow within this area are represented by anomalies of geostrophic velocity as derived from the time series of the sea level anomaly determined from TOPEX/POSEIDON satellite altimeter data. A strong statistical relationship is found between Gulf Stream displacements and parabathic flow over the continental slope. It is such that the southwestward flow over the slope is accelerated when the Gulf Stream is relatively far from the shelf edge, and is decelerated (and perhaps even reversed) when the Gulf Stream is close to the shelf edge. This relationship between Gulf Stream displacements and parabathic flow is also observed in numerical simulations produced by the Miami Isopycnic Coordinate Model. In qualitative terms, it is consistent with the notion that when the Gulf Stream is closer to the 200-m isobath, it is capable of entraining a larger fraction of shelf water masses. Alternatively, when the Gulf Stream is far from the shelf-break, more water is advected into the MAB slope region from the northeast. Analysis of the diabathic flow indicates that much of the cross-slope transport by which the southwestward flow entering the study region is transferred to the northeastward flow exiting the region occurs in a narrow band roughly centered at 36.75°N, order 150 km north of Cape Hatteras. This transport, and thus the cyclonic circulation of the southern MAB, strengthens when the Gulf Stream is relatively close to the shelf edge, and weakens when the Gulf Stream is far from the shelf edge.}, number={2-4}, journal={PROGRESS IN OCEANOGRAPHY}, author={Boehm, E. and Hopkins, T. S. and Pietrafesa, L. J. and Churchill, J. H.}, year={2006}, pages={196–212} }
 @article{lin_xie_pietrafesa_shen_mallin_durako_2006, title={Dissolved oxygen stratification in two micro-tidal partially-mixed estuaries}, volume={70}, ISSN={["1096-0015"]}, DOI={10.1016/j.ecss.2006.06.032}, abstractNote={The controlling physical factors for vertical oxygen stratification in micro-tidal, partially-mixed estuaries are discussed in this paper. A theoretical deduction shows that vertical stratification of dissolved oxygen (DO) concentration can be explained by the extended Hansen and Rattray's Central Region theory, which suggests that in addition to biological factors such as photosynthesis, biochemical oxygen demand (BOD), sediment oxygen demand (SOD), vertical DO profiles are mainly controlled by physical factors such as surface re-aeration, river flow, and estuarine gravitational circulation. Vertical mixing of DO from surface re-aeration and photosynthesis sets a DO profile of higher concentration near the surface and lower near the bottom. With a positive seaward longitudinal DO gradient, strong river flow and estuarine gravitational circulation can cause lower DO concentrations near the surface and higher near the bottom. The actual vertical oxygen profile is then determined by the relative magnitude of the above-mentioned mechanisms. It is sensitive to two parameters: (1) the strength of the gravitational circulation (uE); and (2) the relative importance between biochemical oxygen demand and vertical diffusivity (α). Vertical DO stratification usually becomes weaker as uE increases. The impact of gravitational circulation on vertical oxygen distribution becomes more important for a larger α. The impact of α on oxygen stratification is profound. As uE (and river flow) increases, DO stratification appears to be less sensitive to the value of α. Surface-to-bottom differences in DO concentrations (ΔDO) is negligible when α is small (α < 0.5). As α increases, ΔDO increases under a weak to moderate gravitational circulation mode (uE ≤ 5 cm s−1). Under a strong gravitational circulation mode, ΔDO becomes negative with a small α (α < 2), and as α continues to increase, ΔDO becomes positive. The newly-deduced governing equation for vertical oxygen stratification is applied to two micro-tidal, partially-mixed estuarine systems: the Cape Fear River Estuary (CFRE) and the Pamlico River Estuary (PRE) of North Carolina. In the CFRE, although strong vertical salinity stratification exists, DO concentrations are usually well mixed. De-coupling between salinity stratification and oxygen stratification is mainly due to a relatively stronger estuarine gravitational circulation and higher freshwater inflow in the system. It appears that river flow and gravitational circulation are the dominant factors in controlling oxygen stratification in the CFRE. In contrast, vertical stratification of DO concentrations is closely correlated with that of salinity in the PRE. In the PRE, the estuarine gravitational mode and river flow are often both very weak, and DO stratification is very sensitive to the value of α. With negligible influence from tidal mixing, the system is more sensitive to vertical mixing regulated by salinity stratification and wind. As a result, vertical DO stratification is closely correlated with salinity stratification in the PRE.}, number={3}, journal={ESTUARINE COASTAL AND SHELF SCIENCE}, author={Lin, Jing and Xie, Lian and Pietrafesa, Len J. and Shen, Jian and Mallin, Michael A. and Durako, Michael J.}, year={2006}, month={Nov}, pages={423–437} }
 @article{peng_xie_pietrafesa_2006, title={Tropical cyclone induced asymmetry of sea level surge and fall and its presentation in a storm surge model with parametric wind fields}, volume={14}, ISSN={["1463-5011"]}, DOI={10.1016/j.ocemod.2006.03.004}, abstractNote={The asymmetry of tropical cyclone induced maximum coastal sea level rise (positive surge) and fall (negative surge) is studied using a three-dimensional storm surge model. It is found that the negative surge induced by offshore winds is more sensitive to wind speed and direction changes than the positive surge by onshore winds. As a result, negative surge is inherently more difficult to forecast than positive surge since there is uncertainty in tropical storm wind forecasts. The asymmetry of negative and positive surge under parametric wind forcing is more apparent in shallow water regions. For tropical cyclones with fixed central pressure, the surge asymmetry increases with decreasing storm translation speed. For those with the same translation speed, a weaker tropical cyclone is expected to gain a higher AI (asymmetry index) value though its induced maximum surge and fall are smaller. With fixed RMW (radius of maximum wind), the relationship between central pressure and AI is heterogeneous and depends on the value of RMW. Tropical cyclone’s wind inflow angle can also affect surge asymmetry. A set of idealized cases as well as two historic tropical cyclones are used to illustrate the surge asymmetry.}, number={1-2}, journal={OCEAN MODELLING}, author={Peng, Machuan and Xie, Lian and Pietrafesa, Leonard J.}, year={2006}, pages={81–101} }
 @article{xie_yan_pietrafesa_morrison_karl_2005, title={Climatology and interannual variability of North Atlantic hurricane tracks}, volume={18}, ISSN={["0894-8755"]}, DOI={10.1175/jcli3560.1}, abstractNote={Abstract}, number={24}, journal={JOURNAL OF CLIMATE}, author={Xie, L and Yan, TZ and Pietrafesa, LJ and Morrison, JM and Karl, T}, year={2005}, month={Dec}, pages={5370–5381} }
 @article{xie_yan_pietrafesa_karl_xu_2005, title={Relationship between western North Pacific typhoon activity and Tibetan Plateau winter and spring snow cover}, volume={32}, number={16}, journal={Geophysical Research Letters}, author={Xie, L. and Yan, T. Z. and Pietrafesa, L. J. and Karl, T. and Xu, X. D.}, year={2005} }
 @article{xie_yan_pietrafesa_2005, title={The  effect of Atlantic sea surface temperature dipole mode on hurricanes: Implications for the 2004 Atlantic hurricane season}, volume={32}, number={3}, journal={Geophysical Research Letters}, author={Xie, L. and Yan, T. Z. and Pietrafesa, L.}, year={2005} }
 @article{peng_xie_pietrafesa_2004, title={A numerical study of storm surge and inundation in the Croatan-Albemarle-Pamlico Estuary System}, volume={59}, ISSN={["1096-0015"]}, DOI={10.1016/j.ecss.2003.07.010}, abstractNote={An integrated storm surge and inundation modeling system is used to simulate the storm surge and inundation in the Croatan–Albemarle–Pamlico Estuary System in eastern North Carolina under the influence of 10 hypothetical Category 2 and 3 hurricanes representing typical historical hurricane scenarios in the study region. The integrated storm surge and inundation modeling system is numerically stable in the complex and shallow CAPES environment under hurricane forcing conditions. For an assumed northward or northeastward moving Category 3 hurricane with a translation speed of 25 km/h, the peak storm surge occurs along the western Pamlico Sound and western Albemarle Sound. The most severe flooding as measured by inundation area is in the Pamlico River mouth region where the flooding area reached 500 km2. In general, a more intense or larger hurricane (lower minimum central pressure, MCP or larger radius of maximum wind, RMW) produces higher storm surge and a larger inundation area in the entire region. For the cases considered in this study, the storm surge height and inundation area are more sensitive to MCP than to RMW. Slower translation speed produces higher storm surge, and thus larger inundation area, but the sensitivity of storm surge to storm translation speed can be vastly different for different storms.}, number={1}, journal={ESTUARINE COASTAL AND SHELF SCIENCE}, author={Peng, MC and Xie, L and Pietrafesa, LJ}, year={2004}, month={Jan}, pages={121–137} }
 @article{xie_pietrafesa_peng_2004, title={Incorporation of a mass-conserving inundation scheme into a three dimensional storm surge model}, volume={20}, ISSN={["0749-0208"]}, DOI={10.2112/03-0084r.1}, abstractNote={Abstract The rapid rise and fall of coastal sea level due to tides and storm surge complicates the application of hydrodynamic models that use constant lateral boundaries in the region where sea level change falls within the tidal range or between the negative and positive surge extremes. In order to enable a hydrodynamic model for use in tidal or surge zones, an inundation and drying scheme must be incorporated into the hydrodynamic model. In this study, a mass-conserving inundation (wetting) and draining (drying) scheme is incorporated into a three-dimensional hydrodynamic model (the Princeton Ocean Model, often referred to as POM) for coastal ocean and estuarine systems. This coupled hydrodynamic and inundation modeling system is tested in an idealized lake/estuarine setting. The results show that: 1) incorporation of the inundation/drying scheme into the POM enabled its application in shallow water systems with time-dependent coastal boundaries; 2) the mass conservation constraint used in the inundation and drying scheme eliminates the problem of artificial flooding associated with the imbalance of water mass that is typical of a non-mass-conserving schemes; 3) using vertically-averaged flow as flooding velocity resulted in a reduced flooding area as compared to the cases that use the surface flow as the flooding velocity. This is partly due to the fact that vertically-averaged flow tends to be weaker and directed more parallel to the coastline than the surface flow.}, number={4}, journal={JOURNAL OF COASTAL RESEARCH}, author={Xie, L and Pietrafesa, LJ and Peng, MC}, year={2004}, pages={1209–1223} }
 @article{xie_pietrafesa_wu_2003, title={A numerical study of wave-current interaction through surface and bottom stresses: Coastal ocean response to Hurricane Fran of 1996}, volume={108}, ISSN={["2169-9291"]}, DOI={10.1029/2001jc001078}, abstractNote={A three‐dimensional wave‐current coupled modeling system is used to examine the influence of waves on coastal currents and sea level. This coupled modeling system consists of the wave model‐WAM (Cycle 4) and the Princeton Ocean Model (POM). The results from this study show that it is important to incorporate surface wave effects into coastal storm surge and circulation models. Specifically, we find that (1) storm surge models without coupled surface waves generally under estimate not only the peak surge but also the coastal water level drop which can also cause substantial impact on the coastal environment, (2) introducing wave‐induced surface stress effect into storm surge models can significantly improve storm surge prediction, (3) incorporating wave‐induced bottom stress into the coupled wave‐current model further improves storm surge prediction, and (4) calibration of the wave module according to minimum error in significant wave height does not necessarily result in an optimum wave module in a wave‐current coupled system for current and storm surge prediction.}, number={C2}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS}, author={Xie, L and Pietrafesa, LJ and Wu, K}, year={2003}, month={Feb} }
 @inbook{pietrafesa_xie_dickey_peng_yan_2003, title={North Carolina State University coastal and estuary storm surge and flood prediction system}, ISBN={1853128341}, booktitle={Ecosystems and Sustainable Development IV}, publisher={Southampton; Boston: WIT Press}, author={Pietrafesa, L. J. and Xie, L. and Dickey, D. A. and Peng, M. and Yan, S.}, editor={E. Tiezzi, C. A. Brebbia and Uso, J. L.Editors}, year={2003}, pages={101–110} }
 @article{bright_xie_pietrafesa_2002, title={Evidence of the Gulf Stream's influence on tropical cyclone intensity}, volume={29}, ISSN={["0094-8276"]}, DOI={10.1029/2002gl014920}, abstractNote={Historical storm data and satellite imagery are analyzed to determine the intensity changes and storm‐related characteristics of 53 coastal and landfalling tropical cyclones (TCs) from Florida to North Carolina that passed over the Gulf Stream (GS) during the period 1944–2000. It appears that less intense storms (Category 2 or weaker), as well as those occurring earlier in the Atlantic hurricane season, are more likely to be strengthened by the GS. In addition, 81% of the Category 2 or weaker storms that intensified based on both maximum wind speed (MWS) and minimum central pressure (MCP) had tracks approximately parallel to the GS, while 3 of the 5 major (Category 3–5) hurricanes that intensified based on both MWS and MCP tracked perpendicular to the GS. The presence of an upstream mid‐latitude trough could have contributed to the intensification of the weaker TCs by steering them along the GS.}, number={16}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Bright, RJ and Xie, L and Pietrafesa, LJ}, year={2002}, month={Aug} }
 @article{grothues_cowen_pietrafesa_bignami_weatherly_flagg_2002, title={Flux of larval fish around Cape Hatteras}, volume={47}, ISSN={["0024-3590"]}, DOI={10.4319/lo.2002.47.1.0165}, abstractNote={Convergence of shelf water flows from the Middle and South Atlantic Bights (MAB and SAB) upon Cape Hatteras, North Carolina, presents a potential barrier to the exchange of fish larvae between bights. Impinging water often turns northeastward with the Gulf Stream, and larvae of both cool temperate and warm temperate/subtropical shelf fishes suffer expatriation. Transient oceanographic features exist, however, facilitating shelf retention, cross‐bight exchange, and return of expatriated larvae. The impact of these features is mitigated by specific distribution with relation to hydrography, resulting in a selective permeability of this barrier. Dynamic oceanography may result in dynamic recruitment success. We measured the springtime (1996) flux of seven larval fish species assemblages across the confluence by coupling measured water mass/depth specific larval fish concentration with water mass transport values obtained from an extensive moored instrument survey. Strong flows of shallow shelf water from the MAB to the SAB dominated transport of MAB spawned larvae even for groups with highest concentrations in waters without strong net flows. Most of these larvae passed from the MAB or the open sea into the study region shelf and from there into the SAB. Net flow of SAB water into the convergence retained SAB‐affiliated larvae arriving from the south, but nearshore MAB flows transported low numbers from the MAB to the SAB. The importance of this is tied to the unknown point of introduction of these SAB larvae to MAB waters (e.g., well north of the confluence), but northward exchange of SAB‐spawned fish was always prevented along the southern MAB shelf.}, number={1}, journal={LIMNOLOGY AND OCEANOGRAPHY}, author={Grothues, TM and Cowen, RK and Pietrafesa, LJ and Bignami, F and Weatherly, GL and Flagg, CN}, year={2002}, month={Jan}, pages={165–175} }
 @article{xie_pietrafesa_wu_2002, title={Interannual and decadal variability of landfalling tropical cyclones in the southeast coastal states of the United States}, volume={19}, ISSN={["1861-9533"]}, DOI={10.1007/s00376-002-0007-y}, number={4}, journal={ADVANCES IN ATMOSPHERIC SCIENCES}, author={Xie, L and Pietrafesa, LJ and Wu, KJ}, year={2002}, pages={677–686} }
 @article{flagg_pietrafesa_weatherly_2002, title={Springtime hydrography of the southern Middle Atlantic Bight and the onset of seasonal stratification}, volume={49}, ISSN={["0967-0645"]}, DOI={10.1016/S0967-0645(02)00121-2}, abstractNote={The Ocean Margins Program was a major multi-disciplinary observational effort in the southern Middle Atlantic Bight (MAB), focusing on the transformation, retention, and export of biogenic materials from the shelf. The observational effort peaked in the spring and summer of 1996 with four ship-based surveys, augmented by an array of 26 moorings supporting 126 temperature and 118 salinity sensors. The data from the cruises and moored array are used to describe how the springtime hydrographic evolution takes place in an area in which five water masses locally vie for dominance and that is subject to strong wind stress, heat flux, and offshore forcing. The results show that the region is subject to large-scale intrusions from both the north and south, which materially affect the timing and development of stratified conditions. The intrusions from the north are wind driven and provide cold, moderately saline, unstratifed water, delaying the development of stratified conditions. Intrusions also occur from the south, where warmer and generally more saline waters from the South Atlantic Bight are driven into the area by alongshore winds and/or intrusions of Gulf Stream waters pushed shoreward by Gulf Stream frontal eddies. In 1996, an intrusion of saline water from the south, combined with a reversal of the alongshore winds from the north, slowed the southward flow of cold MAB water, and subsequently caused low-salinity Virginia Coastal Waters to spread out from the coastal plume over the denser water from the north. With the reduced alongshelf flow and an initial stratification provided by the low-salinity coastal water, solar insolation and sensible heat fluxes were then able to warm the surface layer, permanently establishing the seasonal thermocline/halocline for the area not directly impacted by intrusions from the Gulf Stream and South Atlantic Bight.}, number={20}, journal={DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY}, author={Flagg, CN and Pietrafesa, LJ and Weatherly, GL}, year={2002}, pages={4297–4329} }
 @article{pietrafesa_flagg_xie_weatherly_morrison_2002, title={The winter/spring 1996 OMP current, meteorological, sea state and coastal sea level fields}, volume={49}, ISSN={["0967-0645"]}, DOI={10.1016/S0967-0645(02)00166-2}, abstractNote={The time series of atmospheric winds, coastal sea level, surface gravity waves, currents, water temperature, and salinity for the period February–May 1996 across the OMP moored array defined a well-organized physical oceanographic system. The M2 tide, a frictionally modified Poincare wave, was manifested as a clockwise-rotating, elliptically polarized wave, with predominantly cross-shelf orientation of the ellipse, and an axis ratio of ∼0.6 in upper layer waters and in offshore waters. However, bottom friction compressed and rotated the tidal ellipses in shallow and near-bottom waters. Elliptically polarized, clockwise-rotating motions were evident at near-inertial (∼20 h) and diurnal (∼24 h) periods. The wind field was dominated by 2–14 day events centered about 4–8 days. Due to the location and track of mesoscale atmospheric events, the wind field over the southern portion of the array was far more energetic than over the northern portion. The winds prior to 17 April had higher variances than after 17 April. Sub-diurnal frequency currents were dynamically responsive to the wind field at all locations and were stronger in the southern portion of the array. The shelf-wide, southward drift of Middle Atlantic Bight waters contributed to the weekly to monthly scales of motion. Shelf-wide, the record length means were generally southward, with an offshore component in near-bottom waters. However, a significant finding was that near the 21 m isobath on the north line of moorings, just south of the mouth of Chesapeake Bay, the mean flow was into the Bay, providing a means for the import of marine sediment into the estuary. In the southeastern-most corner of the array, north of Diamond Shoals in 36 m of water, the flows were persistently directed offshore. Following southward wind events, an inability to propagate Kelvin waves northward along the coast traps a buildup of water against Diamond Shoals such that the only way for it to relax is through a geostrophically balanced offshore transport of shelf waters. The Chesapeake Bay Plume and Middle Atlantic Bight Waters often breached Diamond Shoals and invaded the South Atlantic Bight during the passage of movement northward with southward-directed wind events, particularly extra-tropical cyclones. Following the mid-April transition to persistent northward winds, Carolina Capes Water moved northward across Diamond Shoals and induced a transition from well-mixed wintertime to vertically stratified summertime hydrographic conditions.}, number={20}, journal={DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY}, author={Pietrafesa, LJ and Flagg, CN and Xie, L and Weatherly, GL and Morrison, JM}, year={2002}, pages={4331–4354} }
 @article{xie_wu_pietrafesa_zhang_2001, title={A numerical study of wave-current interaction through surface and bottom stresses: Wind-driven circulation in the South Atlantic Bight under uniform winds}, volume={106}, ISSN={["2169-9291"]}, DOI={10.1029/2000JC000292}, abstractNote={The influences of surface waves on ocean currents in the coastal waters of the South Atlantic Bight are investigated by using a coupled wave‐current modeling system. The ocean circulation model employed is the three‐dimensional Princeton Ocean Model (POM), and the wave model invoked is an improved third‐generation wave model (WAM). The coupling procedure between the POM and the WAM and the simulated coastal ocean circulation driven by uniform surface winds are presented. The simulated results show that wind waves can significantly affect coastal ocean currents not only through an enhancement of wind stress but also through a modification of bottom stress. Wave‐induced wind stress increases the magnitude of currents both at the surface and near the seabed. On the other hand, wave‐induced bottom stress weakens the currents both at the sea surface and near the seabed. Therefore the net effect of surface wind waves on currents depends on the relative importance of current modulations by wave‐induced wind stress and bottom stress. The results further indicate that at a fixed location, the relative importance of wave‐induced surface and bottom shear stresses in coastal ocean circulation depends on the surface wind field. For the constant wind cases considered in this study, the effect of wave‐induced bottom stress is more significant in along‐shore wind conditions than in cross‐shore wind conditions.}, number={C8}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS}, author={Xie, LA and Wu, KJ and Pietrafesa, L and Zhang, C}, year={2001}, month={Aug}, pages={16841–16855} }
 @article{kim_weatherly_pietrafesa_2001, title={On the mass and salt budgets for a region of the continental shelf in the southern Mid-Atlantic Bight}, volume={106}, ISSN={["2169-9291"]}, DOI={10.1029/2000JC000738}, abstractNote={Two field studies were conducted across and along the continental shelf, one from February to May 1996 (deployment 1) and the other from July to October 1996 (deployment 2) in part to determine the mass and salt budgets of shelf water from south of Cape Henry to north of Cape Hatteras, the southernmost portion of the Mid‐Atlantic Bight. The temporal means of current meter records indicated that most of the water enters the region across its northern boundary near the shelf break as part of a southward, alongshore current and exits the southeast corner as a southeastward flowing current. Estimates of the volume transports indicated that not all the transport across the northern boundary was accounted for by transport across the southern boundary and that the remainder occurred as a broad, diffusive flow across the eastern boundary at the shelf break. Time series of volume transport across northern and southern boundaries were very similar and associated with variations in the alongshore wind stress and sea level, indicative of a geostrophic balance. Examination of the individual current meter records indicated these fluctuations were very barotropic even during deployment 2, which included the stratified summer season. Time series of the volume transport across the eastern boundary at the shelf break strongly mirrored the volume transport across the northern boundary minus that across the southern boundary, suggesting that the inferred eastern boundary transport was real and accommodated whatever the southern boundary could not. The turbulent salt flux across each boundary contributes very little to the net salt flux. The mean and time‐dependent salt fluxes show nearly identical patterns as the respective mass fluxes because the salt fluxes are almost governed by current velocity fields. The instantaneous and mean salt fluxes across each boundary were very well approximated by the instantaneous and mean volume transports across the boundary times the deployment average salinity across that boundary, respectively. The Ocean Margins Program (OMP) moored current and salinity observations appear sufficient to make estimates of the mean and time‐dependent mass and salt balance.}, number={C12}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS}, author={Kim, YY and Weatherly, GL and Pietrafesa, LJ}, year={2001}, month={Dec}, pages={31263–31282} }
 @article{logan_morrison_pietrafesa_hopkins_churchill_2000, title={Physical oceanographic processes affecting inflow/outflow through Beaufort Inlet, North Carolina}, volume={16}, number={4}, journal={Journal of Coastal Research}, author={Logan, D. G. and Morrison, J. M. and Pietrafesa, L. J. and Hopkins, T. S. and Churchill, J.}, year={2000}, pages={1111–1125} }
 @article{li_morrison_pietrafesa_ochadlick_1999, title={Analysis of oceanic internal waves from airborne SAR images}, volume={15}, number={4}, journal={Journal of Coastal Research}, author={Li, X. F. and Morrison, J. and Pietrafesa, L. and Ochadlick, A.}, year={1999}, pages={884–891} }
 @article{xie_pietrafesa_zhang_1999, title={Subinertial response of the Gulf Stream system to Hurricane Fran of 1996}, volume={26}, ISSN={["0094-8276"]}, DOI={10.1029/1999GL002359}, abstractNote={The evidence of subinertial‐frequency (with periods from 2 days to 2 weeks) oceanic response to Hurricane Fran of 1996 is documented. Hurricane Fran traveled northward across the Gulf Stream and then over a cool‐core trough, known as the Charleston Trough, due east of Charleston, SC and in the lee of the Charleston Bump during the period 4–5 September, 1996. During the passage of the storm, the trough closed into a gyre to form an intense cool‐core cyclonic eddy. This cool‐core eddy had an initial size of approximately 130 km by 170 km and drifted northeastward along the Gulf Stream front at a speed of 13 to 15 km/day as a subinertial baroclinic wave. Superimposed on this subinertial‐frequency wave were near‐inertial frequency, internal inertia‐gravity waves formed in the stratified mixed‐layer base after the passage of the storm. The results from a three‐dimensional numerical ocean model confirm the existence of both near‐inertial and subinertial‐frequency waves in the Gulf Stream system during and after the passage of Hurricane Fran. Model results also showed that hurricane‐forced oceanic response can modify Gulf Stream variability at both near‐inertial and subinertial frequencies.}, number={23}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Xie, L and Pietrafesa, LJ and Zhang, C}, year={1999}, month={Dec}, pages={3457–3460} }
 @article{xie_pietrafesa_1999, title={Systemwide modeling of wind and density driven circulation in Croatan-Albemarle-Pamlico Estuary System part I: Model configuration and testing}, volume={15}, number={4}, journal={Journal of Coastal Research}, author={Xie, L. and Pietrafesa, L. J.}, year={1999}, pages={1163–1177} }
 @article{driscoll_janowitz_pietrafesa_1998, title={Baroclinically driven estuarine flow: A perturbation approach}, volume={103}, DOI={10.1029/98JC02376}, abstractNote={The residual circulation and density in a shallow estuary of constant depth and width and flowing at high Rayleigh number (Ra) and small internal Froude number (Fr), based on riverine flow (U∞) and the horizontal density variation, are studied. Criteria under which direct tidal effects on the residual flow can be neglected are established. The effects of varying the bottom boundary condition on the velocity field from free slip to no slip are examined using a linear bottom stress boundary condition. The governing equations are nondimensionalized, expanded in a power series in the small parameter, and the zeroth‐ and first‐order equations governing the density field are solved; these solutions yield the zeroth‐ and first‐order results for the velocity field. The equation governing the density field at lowest order is nonlinear and is solved numerically. The results show that for sufficiently large Ra, the mean transport of salt is balanced by baroclinic advection near the mouth and by horizontal turbulent transport farther upstream. For these large Ra the horizontal structure as well as the vertical structure of the flow is strongly affected by the bottom boundary condition with the salinity disturbances determined under the free‐slip condition extending twice as far upstream as the no‐slip results. For smaller Ra, though still large compared to 1, the mean transport is balanced by horizontal mixing throughout the system, and the bottom boundary condition does not affect the horizontal structure. The penetration distance of oceanic waters, with the internal Fr fixed, increases as Ra increases above 24, reaches a maximum upstream penetration distance of Kh/U∞ when Ra reaches 65, and decreases as Ra increases further. The ratio of entrained oceanic waters to riverine inflow is inversely proportional to the internal Fr to the 2/3 power for very large Ra and becomes proportional to Ra as the latter decreases.}, number={C12}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS}, author={Driscoll, EA and Janowitz, GS and Pietrafesa, LJ}, year={1998}, month={Nov}, pages={27893–27903} }
 @article{xie_pietrafesa_bohm_zhang_li_1998, title={Evidence and mechanism of Hurricane Fran induced cooling in the Charleston trough}, volume={25}, ISSN={["0094-8276"]}, DOI={10.1029/98GL00180}, abstractNote={Evidence of enhanced sea surface cooling during and following the passage of Hurricane Fran in September 1996 over an oceanic depression located on the ocean margin offshore of Charleston, South Carolina (referred to as the Charleston Trough), [Pietrafesa, 1983] is documented. Approximately 4C° of sea surface temperature (SST) reduction within the Charleston Trough following the passage of Hurricane Fran was estimated based on SST imagery from Advanced Very High Resolution Radiometer (AVHRR) on the NOAA‐14 polar orbiting satellite. Simulations using a three‐dimensional coastal ocean model indicate that the largest SST reduction occurred within the Charleston Trough. This SST reduction can be explained by oceanic mixing due to storm‐induced internal inertia‐gravity waves.}, number={6}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Xie, L and Pietrafesa, LJ and Bohm, E and Zhang, C and Li, X}, year={1998}, month={Mar}, pages={769–772} }
 @article{dutton_pietrafesa_snow_1998, title={Priorities of the academic community for the National Weather Service}, volume={79}, ISSN={["1520-0477"]}, DOI={10.1175/1520-0477(1998)079<0761:POTACF>2.0.CO;2}, abstractNote={Ties between the National Weather Service (NWS) and the academic components of atmospheric science have been long standing, strong, and fruitful. Historically, the universities have developed new scientific understanding and new prediction techniques that have allowed the NWS to improve its services. The NWS has made data and facilities available to universities for teaching and research and provided professional opportunities for graduates. Today, NWS executives and forecasters interact with academic scientists and educators in collaborative efforts to ensure success of the NWS modernization and restructuring. The academic community recognizes and appreciates the NWS as the federal operational organization that converts new atmospheric understanding into analysis and prediction protocols that improve service to the public. The NWS is thus a critical link in atmospheric science between research and direct and specific benefits to the nation and, therefore, support for academic atmospheric science depends, in part, on the success of the NWS. Change in two main directions will drive the evolution of the NWS in the next decade or two. First, its atmospheric observation and numerical prediction capabilities must be integrated and optimized as a seamless, end-to-end system that takes advantage of new opportunities for measuring critical variables and observing key processes on the appropriate scales in}, number={5}, journal={BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY}, author={Dutton, JA and Pietrafesa, LJ and Snow, JT}, year={1998}, month={May}, pages={761–763} }
 @article{hickey_pietrafesa_jay_boicourt_1998, title={The Columbia River Plume Study: Subtidal variability in the velocity and salinity fields}, volume={103}, DOI={10.1029/97JC03290}, abstractNote={A comprehensive study of the strongly wind driven midlatitude buoyant plume from the Columbia River, located on the U.S. west coast, demonstrates that the plume has two basic structures during the fall/winter season, namely, a thin (∼5–15 m), strongly stratified plume tending west to northwestward during periods of southward or light northward wind stress and a thicker (∼10–40 m), weakly stratified plume tending northward and hugging the coast during periods of stronger northward stress. The plume and its velocity field respond nearly instantaneously to changes in wind speed or direction, and the wind fluctuations have timescales of 2–10 days. Frictional wind‐driven currents cause the primarily unidirectional flow down the plume axis to veer to the right or left of the axis for northward or southward winds, respectively. Farther downstream, currents turn to parallel rather than cross salinity contours, consistent with a geostrophic balance. In particular, during periods when the plume is separated from the coast, currents tend to flow around the mound of fresher water. At distances exceeding about 20 km from the river mouth, the along‐shelf depth‐averaged flow over the inner to midshelf is linear, and depth‐averaged acceleration is governed to lowest order by the difference between surface and bottom stress alone. In this region, along‐shelf geostrophic buoyancy‐driven currents at ∼5 m (calculated from surface density) and along‐shelf geostrophic wind‐driven currents (computed from a depth‐averaged linear model) are comparable in magnitude (∼10–25 cm s−1).}, number={C5}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS}, author={Hickey, BM and Pietrafesa, LJ and Jay, DA and Boicourt, WC}, year={1998}, month={May}, pages={10339–10368} }
 @article{cione_neuherz_raman_pietrafesa_keeter_li_1998, title={The use of pre-storm boundary-layer baroclinicity in determining and operationally implementing the Atlantic surface cyclone intensification index}, volume={89}, ISSN={["0006-8314"]}, DOI={10.1023/A:1001773019199}, number={2}, journal={BOUNDARY-LAYER METEOROLOGY}, author={Cione, JJ and Neuherz, RA and Raman, S and Pietrafesa, LJ and Keeter, K and Li, XF}, year={1998}, month={Nov}, pages={211–224} }
 @article{xie_pietrafesa_raman_1997, title={Interaction between surface wind and ocean circulation in the Carolina Capes in a coupled low-order model}, volume={17}, ISSN={["0278-4343"]}, DOI={10.1016/S0278-4343(97)00024-1}, abstractNote={Abstract Interactions between surface winds and ocean currents over an east-coast continental shelf are studied using a simple mathematical model. The model physics includes cross-shelf advection of sea surface temperature (SST) by Ekman drift, upwelling due to Ekman transport divergence, differential heating of the low-level atmosphere by a cross-shelf SST gradient, and the Coriolis effect. Additionally, the effects of diabatic cooling of surface waters due to air-sea heat exchange and of the vertical density stratification on the thickness of the upper ocean Ekman layer are considered. The model results are qualitatively consistent with observed wind-driven coastal ocean circulation and surface wind signatures induced by SST. This simple model also demonstrates that two-way air-sea interaction plays a significant role in the subtidal frequency variability of coastal ocean circulation and mesoscale variability of surface wind fields over coastal waters.}, number={12}, journal={CONTINENTAL SHELF RESEARCH}, author={Xie, L and Pietrafesa, LJ and Raman, S}, year={1997}, month={Oct}, pages={1483–1511} }
 @article{pietrafesa_xie_morrison_janowitz_pelissier_keeter_neuherz_1997, title={Numerical modelling and computer visualization of the storm surge in and around the Croatan-Albemarle-Pamlico Estuary system produced by Hurricane Emily of August 1993}, volume={48}, number={4}, journal={Mausam}, author={Pietrafesa, L. J. and Xie, L. and Morrison, J. and Janowitz, G. S. and Pelissier, J. and Keeter, K. and Neuherz, R. A.}, year={1997}, pages={567–578} }