@article{baker_battye_robarge_arya_aneja_2020, title={Modeling and measurements of ammonia from poultry operations: Their emissions, transport, and deposition in the Chesapeake Bay}, volume={706}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2019.1115290}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Baker, Jordan and Battye, William H. and Robarge, Wayne and Arya, S. Pal and Aneja, Viney P.}, year={2020}, month={Mar} }
 @article{pirhalla_heist_perry_hanna_mazzola_arya_aneja_2020, title={Urban wind field analysis from the Jack Rabbit II Special Sonic Anemometer Study}, volume={243}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85089852577&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2020.117871}, abstractNote={The Jack Rabbit II Special Sonic Anemometer Study (JRII-S), a field project designed to examine the flow and turbulence within a systematically arranged mock-urban environment constructed from CONEX shipping containers, is described in detail. The study involved the deployment of 35 sonic anemometers at multiple heights and locations, including a 32 m tall, unobstructed tower located about 115 m outside the building array to document the approach wind flow characteristics. The purpose of this work was to describe the experimental design, analyze the sonic data, and report observed wind flow patterns within the urban canopy in comparison to the approaching boundary layer flow. We show that the flow within the building array follows a tendency towards one of three generalized flow regimes displaying channeling over a wide range of wind speeds, directions, and stabilities. Two or more sonic anemometers positioned only a few meters apart can have vastly different flow patterns that are dictated by the building structures. Within the building array, turbulence values represented by normalized vertical velocity variance ( σw2 ) are at least two to three times greater than that in the approach flow. There is also little evidence that σw2 measured at various heights or locations within the JRII array is a strong function of stability type in contrast to the approach flow. The results reinforce how urban areas create complicated wind patterns, channeling effects, and localized turbulence that can impact the dispersion of an effluent release. These findings can be used to inform the development of improved wind flow algorithms to better characterize pollutant dispersion in fast-response models.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Pirhalla, Michael and Heist, David and Perry, Steven and Hanna, Steven and Mazzola, Thomas and Arya, S. Pal and Aneja, Viney}, year={2020}, month={Dec} }
 @article{niyogi_pyle_lei_arya_kishtawal_shepherd_chen_wolfe_2011, title={Urban Modification of Thunderstorms: An Observational Storm Climatology and Model Case Study for the Indianapolis Urban Region}, volume={50}, ISSN={["1558-8432"]}, DOI={10.1175/2010jamc1836.1}, abstractNote={AbstractA radar-based climatology of 91 unique summertime (May 2000–August 2009) thunderstorm cases was examined over the Indianapolis, Indiana, urban area. The study hypothesis is that urban regions alter the intensity and composition/structure of approaching thunderstorms because of land surface heterogeneity. Storm characteristics were studied over the Indianapolis region and four peripheral rural counties approximately 120 km away from the urban center. Using radar imagery, the time of event, changes in storm structure (splitting, initiation, intensification, and dissipation), synoptic setting, orientation, and motion were studied. It was found that more than 60% of storms changed structure over the Indianapolis area as compared with only 25% over the rural regions. Furthermore, daytime convection was most likely to be affected, with 71% of storms changing structure as compared with only 42% at night. Analysis of radar imagery indicated that storms split closer to the upwind urban region and merge again downwind. Thus, a larger portion of small storms (50–200 km2) and large storms (>1500 km2) were found downwind of the urban region, whereas midsized storms (200–1500 km) dominated the upwind region. A case study of a typical storm on 13 June 2005 was examined using available observations and the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5), version 3.7.2. Two simulations were performed with and without the urban land use/Indianapolis region in the fourth domain (1.33-km resolution). The storm of interest could not be simulated without the urban area. Results indicate that removing the Indianapolis urban region caused distinct differences in the regional convergence and convection as well as in simulated base reflectivity, surface energy balance (through sensible heat flux, latent heat flux, and virtual potential temperature changes), and boundary layer structure. Study results indicate that the urban area has a strong climatological influence on regional thunderstorms.}, number={5}, journal={JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY}, author={Niyogi, Dev and Pyle, Patrick and Lei, Ming and Arya, S. Pal and Kishtawal, Chandra M. and Shepherd, Marshall and Chen, Fei and Wolfe, Brian}, year={2011}, month={May}, pages={1129–1144} }
 @article{aneja_arya_rumsey_kim_bajwa_arkinson_semunegus_dickey_stefanski_todd_et al._2008, title={Characterizing ammonia emissions from swine farms in eastern North Carolina: Part 2 - Potential environmentally superior technologies for waste treatment}, volume={58}, ISSN={["2162-2906"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-53849100726&partnerID=MN8TOARS}, DOI={10.3155/1047-3289.58.9.1145}, abstractNote={Abstract The need for developing environmentally superior and sustainable solutions for managing the animal waste at commercial swine farms in eastern North Carolina has been recognized in recent years. Program OPEN (Odor, Pathogens, and Emissions of Nitrogen), funded by the North Carolina State University Animal and Poultry Waste Management Center (APWMC), was initiated and charged with the evaluation of potential environmentally superior technologies (ESTs) that have been developed and implemented at selected swine farms or facilities. The OPEN program has demonstrated the effectiveness of a new paradigm for policy-relevant environmental research related to North Carolina’s animal waste management programs. This new paradigm is based on a commitment to improve scientific understanding associated with a wide array of environmental issues (i.e., issues related to the movement of N from animal waste into air, water, and soil media; the transmission of odor and odorants; disease-transmitting vectors; and airborne pathogens). The primary focus of this paper is on emissions of ammonia (NH3) from some potential ESTs that were being evaluated at full-scale swine facilities. During 2-week-long periods in two different seasons (warm and cold), NH3 fluxes from water-holding structures and NH3 emissions from animal houses or barns were measured at six potential EST sites: (1) Barham farm—in-ground ambient temperature anaerobic digester/energy recovery/greenhouse vegetable production system; (2) BOC #93 farm—upflow biofiltration system—EKOKAN ; (3) Carrolls farm—aerobic blanket system—ISSUES-ABS; (4) Corbett #1 farm—solids separation/gasification for energy and ash recovery centralized system—BEST; (5) Corbett #2 farm—solid separation/reciprocating water technology—ReCip; and (6) Vestal farm—Recycling of Nutrient, Energy and Water System—ISSUES—RENEW. The ESTs were compared with similar measurements made at two conventional lagoon and spray technology (LST) farms (Moore farm and Stokes farm). A flow-through dynamic chamber system and two sets of open-path Fourier transform infrared (OP-FTIR) spectrometers measured NH3 fluxes continuously from water-holding structures and emissions from housing units at the EST and conventional LST sites. A statisticalobservational model for lagoon NH3 flux was developed using a multiple linear regression analysis of 15-min averaged NH3 flux data against the relevant environmental parameters measured at the two conventional farms during two different seasons of the year. This was used to compare the water-holding structures at ESTs with those from lagoons at conventional sites under similar environmental conditions. Percentage reductions in NH3 emissions from different components of each potential EST, as well as the whole farm on which the EST was located were evaluated from the estimated emissions from water-holding structures, barns, etc., all normalized by the appropriate nitrogen excretion rate at the potential EST farm, as well as from the appropriate conventional farm. This study showed that ammonia emissions were reduced by all but one potential EST for both experimental periods. However, on the basis of our evaluation results and analysis and available information in the scientific literature, the evaluated alternative technologies may require additional technical modifications to be qualified as unconditional ESTs relative to NH3 emissions reductions.}, number={9}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Aneja, Viney P. and Arya, S. Pal and Rumsey, Ian C. and Kim, D. -S. and Bajwa, K. and Arkinson, H. L. and Semunegus, H. and Dickey, D. A. and Stefanski, L. A. and Todd, L. and et al.}, year={2008}, month={Sep}, pages={1145–1157} }
 @article{aneja_arya_kim_rumsey_arkinson_semunegus_bajwa_dickey_stefanski_todd_et al._2008, title={Characterizing ammonia emissions from swine farms in eastern north carolina: Part 1-conventional lagoon and spray technology for waste treatment}, volume={58}, ISSN={["1047-3289"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-53849107841&partnerID=MN8TOARS}, DOI={10.3155/1047-3289.58.9.1130}, abstractNote={Abstract Ammonia (NH3) fluxes from waste treatment lagoons and barns at two conventional swine farms in eastern North Carolina were measured. The waste treatment lagoon data were analyzed to elucidate the temporal (seasonal and diurnal) variability and to derive regression relationships between NH3 flux and lagoon temperature, pH and ammonium content of the lagoon, and the most relevant meteorological parameters. NH3 fluxes were measured at various sampling locations on the lagoons by a flow-through dynamic chamber system interfaced to an environmentally controlled mobile laboratory. Two sets of open-path Fourier transform infrared (FTIR) spectrometers were also used to measure NH3 concentrations for estimating NH3 emissions from the animal housing units (barns) at the lagoon and spray technology (LST) sites.Two different types of ventilation systems were used at the two farms. Moore farm used fan ventilation, and Stokes farm used natural ventilation. The early fall and winter season intensive measurement campaigns were conducted during September 9 to October 11, 2002 (lagoon temperature ranged from 21.2 to 33.6 °C) and January 6 to February 2, 2003 (lagoon temperature ranged from 1.7 to 12 °C), respectively. Significant differences in seasonal NH3 fluxes from the waste treatment lagoons were found at both farms. Typical diurnal variation of NH3 flux with its maximum value in the afternoon was observed during both experimental periods. Exponentially increasing flux with increasing surface lagoon temperature was observed, and a linear regression relationship between logarithm of NH3 flux and lagoon surface temperature (T l) was obtained. Correlations between lagoon NH3 flux and chemical parameters, such as pH, total Kjeldahl nitrogen (TKN), and total ammoniacal nitrogen (TAN) were found to be statistically insignificant or weak. In addition to lagoon surface temperature, the difference (D) between air temperature and the lagoon surface temperature was also found to influence the NH3 flux, especially when D > 0 (i.e., air hotter than lagoon). This hot-air effect is included in the statistical-observational model obtained in this study, which was used further in the companion study (Part II), to compare the emissions from potential environmental superior technologies to evaluate the effectiveness of each technology.}, number={9}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Aneja, Viney P. and Arya, S. Pal and Kim, D. -S. and Rumsey, Ian C. and Arkinson, H. L. and Semunegus, H. and Bajwa, K. S. and Dickey, D. A. and Stefanski, L. A. and Todd, L. and et al.}, year={2008}, month={Sep}, pages={1130–1144} }
 @article{bajwa_arya_aneja_2008, title={Modeling studies of ammonia dispersion and dry deposition at some hog farms in North Carolina}, volume={58}, ISSN={["1047-3289"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-53849137372&partnerID=MN8TOARS}, DOI={10.3155/1047-3289.58.9.1198}, abstractNote={Abstract A modeling study was conducted on dispersion and dry deposition of ammonia taking one hog farm as a unit. The ammonia emissions used in this study were measured under our OPEN (Odor, Pathogens, and Emissions of Nitrogen) project over a waste lagoon and from hog barns. Meteorological data were also collected at the farm site. The actual layout of barns and lagoons on the farms was used to simulate dry deposition downwind of the farm. Dry deposition velocity, dispersion, and dry deposition of ammonia were studied over different seasons and under different stability conditions using the short-range dispersion/air quality model, AERMOD. Dry deposition velocities were highest under near-neutral conditions and lowest under stable conditions. The highest deposition at short range occurred under nighttime stable conditions and the lowest occurred during daytime unstable conditions. Significant differences in deposition over crop and grass surfaces were observed under stable conditions.}, number={9}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Bajwa, Kanwardeep S. and Arya, S. Pal and Aneja, Viney P.}, year={2008}, month={Sep}, pages={1198–1207} }
 @article{aneja_arya_rumsey_kim_bajwa_williams_2008, title={Characterizing ammonia emissions from swine farms in eastern North Carolina: Reduction of emissions from water-holding structures at two candidate superior technologies for waste treatment}, volume={42}, ISSN={["1352-2310"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-41449117100&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2007.08.037}, abstractNote={Abstract Program OPEN (Odor, Pathogens, and Emissions of Nitrogen) was an integrated study of the emissions of ammonia (NH 3 ), odor and odorants, and pathogens from potential environmentally superior technologies (ESTs) for swine facilities in eastern North Carolina. This paper, as part of program OPEN, focuses on quantifying emissions of NH 3 from water-holding structures at two of the best ESTs and compares them with the projected emissions from two conventional lagoon and spray technologies (LSTs). The evaluated ESTs are: (1) Super Soils at Goshen Ridge; and (2) Environmental Technologies at Red Hill. The water-holding structures for these two ESTs contained no conventional anaerobic lagoon. A dynamic flow-through chamber was used to measure NH 3 fluxes from the water-holding structures at both the ESTs and at the conventional LST farms. In order to compare the emissions from the water-holding structures at the ESTs with those from the lagoons at the conventional sites under similar conditions, a statistical-observational model for lagoon NH 3 emissions was used. A mass-balance approach was used to quantify the emissions. All emissions were normalized by nitrogen-excretion rates. The percentage reductions relative to the conventional lagoons were calculated for the two ESTs. Results showed substantial reductions in NH 3 emissions at both ESTs. Super Soils had reductions of 94.7% for the warm season and 99.0% for the cool season. Environmental Technologies had slightly larger reductions of 99.4% and 99.98% for the cool and warm season, respectively. As a result of such large reductions in ammonia emissions, both technologies meet the criteria to be classified as ESTs for ammonia emissions.}, number={14}, journal={ATMOSPHERIC ENVIRONMENT}, author={Aneja, Viney P. and Arya, S. Pal and Rumsey, Ian C. and Kim, D-S. and Bajwa, K. S. and Williams, C. M.}, year={2008}, month={Apr}, pages={3291–3300} }
 @article{zhang_wu_krishnan_wang_queen_aneja_arya_2008, title={Modeling agricultural air quality: Current status, major challenges, and outlook}, volume={42}, ISSN={["1873-2844"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-41549095063&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2007.01.063}, abstractNote={Agricultural air quality is an important emerging area of atmospheric sciences that represents significant challenges in many aspects of research including measurements, modeling, regulations, emission control, and operation managements. This work presents a review of current status, major challenges, and future research needs and opportunities of several important aspects of agricultural air quality modeling including chemical species, concentration and deposition measurements for model verification, emission inventories, major physical and chemical processes, model application and evaluation, and policy implications.}, number={14}, journal={ATMOSPHERIC ENVIRONMENT}, author={Zhang, Yang and Wu, Shiang-Yuh and Krishnan, Srinath and Wang, Kai and Queen, Ashley and Aneja, Viney P. and Arya, S. Pal}, year={2008}, month={Apr}, pages={3218–3237} }
 @article{bajwa_aneja_arya_2006, title={Measurement and estimation of ammonia emissions from lagoon-atmosphere interface using a coupled mass transfer and chemical reactions model, and an equilibrium model}, volume={40}, ISSN={["1352-2310"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33748805536&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2005.12.076}, abstractNote={Ammonia has recently gained importance for its increasing atmospheric concentrations and its role in the formation of aerosols. The anaerobic lagoon and spray method, commonly used for waste storage and disposal in confined animal feeding operations (CAFO), is a significant source of ammonia emissions. An accurate emission model for ammonia from aqueous surfaces can help in the development of emission factors. Data collected from field measurements made at hog waste lagoons in south eastern North Carolina, using the flow through dynamic chamber technique, were used to evaluate the Coupled mass transfer and Chemical reactions model and Equilibrium model developed by Aneja et al. [2001a. Measurement and modeling of ammonia emissions at waste treatment lagoon-Atmospheric Interface. Water, Air and Soil pollution: Focus 1, 177–188]. Sensitivity analysis shows that ammonia flux increases exponentially with lagoon temperature and pH, but a linear increase was observed with an increase in total ammoniacal nitrogen (TAN). Ammonia flux also shows a nonlinear increase with increasing wind speed. Observed ammonia fluxes were generally lower in the cold season than in the warm season when lagoon temperatures are higher. About 41% of the equilibrium model predictions and 43% of the Coupled model predictions are found to be within a factor of two of the observed fluxes. Several model performance statistics were used to evaluate the performance of the two models against the observed flux data. These indicate that the simpler Equilibrium model does as well as the Coupled model. The possible effects of the "artificial" environment within the chamber, which is different from that in the ambient atmospheric conditions above the open lagoon surface, on the measured fluxes are also recognized.}, number={SUPPL. 2}, journal={ATMOSPHERIC ENVIRONMENT}, author={Bajwa, Kanwardeep S. and Aneja, Viney P. and Arya, S. Pal}, year={2006}, pages={S275–S286} }
 @article{arya_2005, title={Micrometeorology and atmospheric boundary layer}, volume={162}, ISSN={["1420-9136"]}, DOI={10.1007/s00024-005-2690-y}, number={10}, journal={PURE AND APPLIED GEOPHYSICS}, author={Arya, SP}, year={2005}, month={Oct}, pages={1721–1745} }
 @article{phillips_arya_aneja_2004, title={Ammonia flux and dry deposition velocity from near-surface concentration gradient measurements over a grass surface in North Carolina}, volume={38}, ISSN={["1352-2310"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-2442425948&partnerID=MN8TOARS}, DOI={10.1016/j.atmosenv.2004.02.054}, abstractNote={Atmospheric ammonia concentrations were measured during fall 2001, winter, spring, and summer 2002 over natural surfaces in North Carolina where animal farms and waste storage and treatment lagoons (which are known to emit ammonia) at two heights (2 and 6 m) above the surface employing an arrangement of two Thermo Environmental Instruments, Inc. Model 17C chemiluminescent nitrogen oxides (NOX)–ammonia (NH3) analyzers along with a solenoid for each analyzer to alternate measurements between the two elevations. Simultaneously, mean winds and temperatures are also measured at the same two heights. The micrometeorological gradient method is used in conjunction with the Monin–Obukhov similarity theory, to estimate the vertical flux and dry deposition velocity of ammonia under different meteorological conditions. Diurnal and seasonal variations of ammonia flux and dry deposition velocity were investigated under a wide range of wind and atmospheric stability conditions yielding hourly variation of NH3 fluxes and deposition during each seasonal campaign. Fall average NH3 concentrations were generally the highest with daytime concentrations of 7.60±6.54 μg m−3 at 2 m, while nighttime NH3 concentrations were 7.25±6.14 μg m−3 at 2 m. The winter season had the lowest overall concentrations collected during each seasonal campaign with averages of 1.73±2.00 μg m−3 (2 m) during daytime and 1.37±1.50 μg m−3 (2 m) during nighttime. Deposition and emission occur, both on daily and seasonal scales. Summer measurements yielded the largest average daytime deposition velocity of 3.94±2.79 cm s−1, whereas winter measurements gave the lowest daytime velocities with an average of 2.41±1.92 cm s−1. The largest nighttime deposition velocities were estimated during the summer season with an average of 0.76±1.69 cm s−1, whereas fall nighttime deposition velocities were considerably lower at 0.07±0.17 cm s−1. Regression relationships between the ammonia deposition velocity and the friction velocity are obtained for different stability conditions.}, number={21}, journal={ATMOSPHERIC ENVIRONMENT}, author={Phillips, SB and Arya, SP and Aneja, VP}, year={2004}, month={Jul}, pages={3469–3480} }
 @book{arya_2001, title={Introduction to micrometeorology (2nd ed.)}, ISBN={0120593548}, publisher={San Diego, CA: Academic Press}, author={Arya, S. P. S}, year={2001} }
 @article{aneja_arya_li_murray_manuszak_2000, title={Climatology of diurnal trends and vertical distribution of ozone in the atmospheric boundary layer in urban North Carolina}, volume={50}, ISSN={["1047-3289"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0033627172&partnerID=MN8TOARS}, DOI={10.1080/10473289.2000.10463984}, abstractNote={ABSTRACT Vertical measurements of ozone were made on a 610-m-tall tower located about 15 km southeast of Raleigh, NC, as part of an effort by the state of North Carolina to develop a state implementation plan (SIP) for ozone control in the Raleigh Metropolitan Statistical Area. During summer 1993, 1994, and 1995, ozone was monitored at ground level, 250 m, and 433 m. Boundary layer wind, temperature, and other meteorological variable profiles were determined from balloon soundings. During summer 1996 and 1997, ozone was monitored at ground level, 76 m, 128 m, and 433 m. This paper presents the analysis and discussion of the five-year data. The evolutions of the convective boundary layer during daytime and the stable nocturnal boundary layer (NBL) were found to have marked impacts on ozone concentrations. A strong diurnal pattern, with an afternoon maximum and an early morning minimum, was dominant at ground level, but it was much weaker at elevated levels and insignificant above the NBL at night. Ozone deposition velocities at night during the measurement periods were estimated to range from 0.09 to 0.64 cm/sec. We found evidence of regional transport of ozone and/or its precursors from northwest and north of the site, which may play a role in high ozone events in the Raleigh-Durham area.}, number={1}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Aneja, VP and Arya, SP and Li, YX and Murray, GC and Manuszak, TL}, year={2000}, month={Jan}, pages={54–64} }
 @article{aneja_mathur_arya_li_murray_manuszak_2000, title={Coupling the vertical distribution of ozone in the atmospheric boundary layer}, volume={34}, ISSN={["0013-936X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034195280&partnerID=MN8TOARS}, DOI={10.1021/es990997+}, abstractNote={Vertical measurements of ozone were made on a 610 m tall tower located about 15 km southeast of Raleigh, NC, as part of an effort by the State of North Carolina to develop a State Implementation Plan (SIP) for ozone control in the Raleigh Metropolitan Statistical Area and other metropolitan areas in the state. Ozone was monitored at 10, 250, and 433 m height levels during the summer months of 1993−1995 and at 10, 76, 128, and 433 m height levels during the summer months of 1996−1997. A regional atmospheric chemistry/transport model, called Multiscale Air Quality Simulation Platform (MAQSIP), was also employed to simulate three-dimensional O3 distribution over the eastern United States for a 2-month period (June 1−July 31, 1995). Through complementary analyses of the 5-year data and the modeling results, this paper examines the vertical distribution of ozone concentrations in the atmospheric boundary layer with the emphasis on the contribution of residual ozone aloft to the ground level ozone enhancement d...}, number={11}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Aneja, VP and Mathur, R and Arya, SP and Li, YX and Murray, GC and Manuszak, TL}, year={2000}, month={Jun}, pages={2324–2329} }
 @article{han_lin_schowalter_arya_2000, title={Large eddy simulation of aircraft wake vortices within homogeneous turbulence: Crow instability}, volume={38}, ISSN={["0001-1452"]}, DOI={10.2514/2.956}, abstractNote={Ambient atmospheric turbulence effects on aircraft wake vortices are studied using a validated large eddy simulationmodel. Our results conŽ rm that the most ampliŽ ed wavelength of the Crow instability and the lifetime of wake vortices are signiŽ cantly in uenced by ambient turbulence (Crow, S. C., “Stability Theory for a Pair of TrailingVortices,” AIAA Journal, Vol. 8, No. 12, 1970,pp. 2172–2179). The Crow instabilitybecomeswell developed in most atmospheric turbulence levels, but in strong turbulence the vortex pair deforms more irregularly due to turbulence advection. The most ampliŽ ed wavelength of the instability decreases with increasing dimensionless turbulence intensity , although it increases with increasing turbulence integral length scale. The vortex lifespan is controlled primarily by and decreases with increasing , whereas the effect of integral scale of turbulence on vortex lifespan is of minor importance. The lifespan is estimated to be about 40% larger than Crow and Bate’s predicted value (Crow, S. C., and Bate, E. R., “Lifespan of Trailing Vortices on a Turbulent Atmosphere,” Journal of Aircraft, Vol. 13, No. 7, 1976, pp. 476–482) but in agreement with Sarpkaya’s recent modiŽ cation (Sarpkaya, T., “Decay of Wake Vortices of Large Aircraft,” AIAA Journal, Vol. 36, No. 9, 1998, pp. 1671–1679) to Crow and Bate’s theory. This larger lifespan is also supported by data from water tank experiments and direct numerical simulations. There appears to be a possibility that the scatter in vortex lifespans due to ambient turbulence alone decreases with increasing Reynoldsnumber, whereas larger scatter of lifespans in  ight tests may result from other factors such as stratiŽ cation, wind shear, and inhomogeneous ambient turbulence.}, number={2}, journal={AIAA JOURNAL}, author={Han, JG and Lin, YL and Schowalter, DG and Arya, SP}, year={2000}, month={Feb}, pages={292–300} }
 @article{han_lin_arya_proctor_2000, title={Numerical study of wake vortex decay and descent in homogeneous atmospheric turbulence}, volume={38}, ISSN={["1533-385X"]}, DOI={10.2514/2.1006}, abstractNote={Numerical simulations are performed to isolate the effect of ambient turbulence on the wake vortex decay rate within a neutrally stratified atmosphere. Simulations are conducted for a range of turbulence intensities by injecting wake vortex pairs into an approximately homogeneous and isotropic turbulence field. Consistent with field observations, the decay rate of the vortex circulation increases clearly with increasing levels of ambient turbulence. Based on the results from the numerical simulations, simple decay models for the vortex pair are proposed as functions of nondimensional ambient turbulence intensity, nondimensional radial distance, and nondimensional time. For strong atmospheric turbulence, the model predictions are in reasonable agreement with the observational data. For weak turbulence with stable stratification, the model, based on turbulence dissipation alone, underestimates circulation decay with consistent overestimation of vortex descent, unless stratification effects are included}, number={4}, journal={AIAA JOURNAL}, author={Han, J and Lin, YL and Arya, SP and Proctor, FH}, year={2000}, month={Apr}, pages={643–656} }
 @book{arya_1999, title={Air pollution meteorology and dispersion}, ISBN={0195073983}, publisher={New York: Oxford University Press}, author={Arya, S. P.}, year={1999} }
 @article{arya_1999, title={Comments on "wind and temperature profiles in the radix layer: The bottom fifth of the convective boundary layer"}, volume={38}, ISSN={["0894-8763"]}, DOI={10.1175/1520-0450(1999)038<0493:COWATP>2.0.CO;2}, abstractNote={AbstractNo abstract available. Corresponding author address: Dr. S. Pal Arya, Dept. of Marine, Earth and Atmospheric Science, North Carolina State University, Raleigh, NC 27695-8208.sparya@unity.ncsu.edu}, number={4}, journal={JOURNAL OF APPLIED METEOROLOGY}, author={Arya, SP}, year={1999}, month={Apr}, pages={493–494} }
 @article{li_aneja_arya_rickman_brittig_roelle_kim_1999, title={Nitric oxide emission from intensively managed agricultural soil in North Carolina}, volume={104}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-17044382146&partnerID=MN8TOARS}, DOI={10.1029/1999JD900336}, abstractNote={Emissions of nitric oxide (NO) were determined from an intensively managed agricultural soil near Plymouth, in the coastal plain of North Carolina, using the dynamic chamber technique. The measurements were made over a soybean field from July 15 to August 15, 1996, as part of the project Natural Emissions of Oxidant Precursors: Validation of Techniques and Assessment (NOVA). A N‐containing fertilizer was applied at the middle of the experiment in order to investigate the effect of N‐fertilizers on NO emissions and to test the response of instruments. Soil water content was high during the experimental period, with water‐filled pore space ranging from 49% to 67%. NO emission during this period ranged between 0.28 and 18.45 ng N m−2 s−1, with an overall average of 5.01±3.03 ng N m−2 s−1. A normal diurnal pattern with low values at nighttime and high values during the day was observed during the prefertilization period, but a reverse diurnal pattern (high at nighttime, low in daytime) of NO emission variation was found during the postfertilization, closed‐canopy period, implying that interaction among canopy development, application of fertilization, and soil parameters may affect the diurnal variation of NO emission from soils. The emissions of NO were related to soil temperature, water‐filled pore space, and extractable nitrogen. Application of fertilizer at the middle of the experiment was found to disrupt the normal relations between NO emission and soil temperature and water content seen during the prefertilization period but to enhance the positive relation between NO emission and extractable N. An intercomparison of the dynamic chamber technique with the eddy‐correlation technique in this experiment indicates that in spite of large differences in the magnitudes of soil NO emission and the NO flux at 5 m, the two fluxes show similar variations with time and are strongly correlated.}, number={D21}, journal={Journal of Geophysical Research Atmospheres}, author={Li, Y. and Aneja, Viney and Arya, S.P. and Rickman, J. and Brittig, J. and Roelle, P. and Kim, D.S.}, year={1999}, pages={26115–26123} }
 @article{aneja_oommen_riordan_arya_wayland_murray_1999, title={Ozone patterns for three metropolitan statistical areas in North Carolina, USA}, volume={33}, ISSN={["1352-2310"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0032599714&partnerID=MN8TOARS}, DOI={10.1016/S1352-2310(99)00241-1}, abstractNote={As part of an effort by the state of North Carolina to develop a State Implementation Plan (SIP) for 1-h peak ozone control, a network of ozone stations was established to monitor surface ozone concentrations across the state. Between 19 and 23 ozone stations made continuous surface measurements between 1993 and 1995 surrounding three major metropolitan statistical areas (MSAs): Raleigh/Durham (RDU), Charlotte/Mecklenburg (CLT), and Greensboro/High Point/Winston-Salem (GSO). Statistical averages of the meteorological and ozone data were performed at each Metropolitan Statistical Area (MSA) to study trends and/or relationships on high ozone days (days in which one of the MSA sites measured an hourly ozone concentration⩾90.0 ppbv). County emission maps of precursor gases, wind roses, total area averages of ozone, total downwind averages of ozone deviations, upwind averages of ozone, and a modified delta ozone analysis were all obtained and analyzed. The results of this study show a reduction in the delta ozone relative to an earlier study at RDU, but no average significant change at CLT (no comparison can be made for GSO). The statistical data analyses in this study are used to quantify the importance of local contributions and regional transport, to ozone air pollution in the MSAs.}, number={30}, journal={ATMOSPHERIC ENVIRONMENT}, author={Aneja, VP and Oommen, RG and Riordan, AJ and Arya, SP and Wayland, RJ and Murray, GC}, year={1999}, month={Dec}, pages={5081–5093} }
 @article{zhu_arya_snyder_1998, title={An experimental study of the flow structure within a dense gas plume}, volume={62}, ISSN={["0304-3894"]}, DOI={10.1016/S0304-3894(98)00162-9}, abstractNote={A wind tunnel study was conducted to examine how a dense gas plume could affect the mean flow and turbulence structure of the boundary layer containing the plume. For this, a neutral atmospheric boundary layer developing over an aerodynamically rough surface was simulated in the US EPA's Meteorological Wind Tunnel. The dense gas plume was created by releasing CO2 through a small circular source at ground level. A procedure was developed to make reasonably accurate mean velocity and turbulence measurements within the dense gas plumes by using hot-film anemometry in a range where the probe response was insensitive to the concentration of CO2. Both the flow visualization and quantitative measurements of concentration and velocity fields indicated that, at low wind speeds, the dense gas plumes exhibited significant buoyancy effects on the flow structure. Within the dense plumes, mean velocity profiles were observed to have changed significantly in shape, with reduced speeds near the surface and increased velocities farther away from the surface. Consistent with these changes in mean velocity profiles, significant reductions in the roughness length and friction velocity were observed. Both the longitudinal and vertical turbulence intensities were also found to be greatly reduced within the dense plumes at low wind speeds. These changes in mean flow and turbulence structure were not only related to the dense-gas concentrations, but also to the local velocity gradients and the growth of the dense plumes with distance from the source. The local gradient Richardson number is found to be the most appropriate parameter for describing the changes in the mean flow and turbulence structure. Significant dense gas effects were observed when the Richardson number increased beyond its critical value (0.25) for the dynamic stability of a stratified flow. Our experimental results show that, in an existing turbulent flow, turbulence is not completely suppressed even when the gradient Richardson number exceeds one.}, number={2}, journal={JOURNAL OF HAZARDOUS MATERIALS}, author={Zhu, GW and Arya, SP and Snyder, WH}, year={1998}, month={Sep}, pages={161–186} }
 @inbook{arya_1998, title={Unstable and convective boundary layers}, ISBN={1853124273}, booktitle={Dynamics of atmospheric flows: Atmospheric transport and diffusion processes}, publisher={Boston: Computational Mechanics Publications}, author={Arya, S. P.}, editor={M. P. Singh and Raman, S.Editors}, year={1998}, pages={1–38} }
 @article{lu_arya_snyder_lawson_1997, title={A laboratory study of the urban heat island in a calm and stably stratified environment .1. Temperature field}, volume={36}, ISSN={["0894-8763"]}, DOI={10.1175/1520-0450(1997)036<1377:ALSOTU>2.0.CO;2}, abstractNote={An extensive and systematic water-tank study was performed to simulate the urban heat island under a calm and stably stratified environment. The objective was to examine the mean-temperature field, mixing height, and heat-island intensity as functions of surface heating rates, heat-island sizes, and ambient temperature gradients. The scaling parameters for the temperature field associated with the heat-island plume are the diameter D, surface heating rate H0, and Brunt–Väisälä frequency N of the ambient stratification. The induced plume was turbulent, and the Froude number was found to be the most important similarity parameter. The differences between low- and high-aspect-ratio plumes are discussed, and simple theoretical models are proposed for low-aspect-ratio plumes. The experimental results generally confirm the theoretical predictions and agree reasonably well with field observations, in spite of several limitations of the laboratory simulation. The mean-temperature distributions are found to have a universal shape that is a function of location only. The results are described in two papers. In this paper, the temperature fields are described. Part II describes the velocity fields and develops analytical models that apply to low-aspect-ratio plumes.}, number={10}, journal={JOURNAL OF APPLIED METEOROLOGY}, author={Lu, J and Arya, SP and Snyder, WH and Lawson, RE}, year={1997}, month={Oct}, pages={1377–1391} }
 @article{lu_arya_snyder_lawson_1997, title={A laboratory study of the urban heat island in a calm and stably stratified environment .2. Velocity field}, volume={36}, ISSN={["0894-8763"]}, DOI={10.1175/1520-0450(1997)036<1392:ALSOTU>2.0.CO;2}, abstractNote={Abstract A fully turbulent, low-aspect-ratio buoyant plume with no initial momentum under calm and stably stratified conditions is produced in a convection tank. The plume is generated by a circular heat island at the bottom of the tank. Two analytical models, a bulk convection model and a hydrostatic model, are developed to formulate similarity relations for the low-aspect-ratio plume. The convective velocity scale wD, suggested by the analytical models, is used as the similarity parameter for both the mean velocity and standard deviations of velocity fluctuations. The normalized standard deviations of horizontal and vertical velocities agree with each other for two heating rates, as well as with field observations in the center of Sapporo, Japan. The suggested scaling and empirical relations based on our experimental results may be applied to the velocity fields of other low-aspect-ratio plumes in calm and stably stratified environments. Further investigations are recommended to confirm the results of t...}, number={10}, journal={JOURNAL OF APPLIED METEOROLOGY}, author={Lu, J and Arya, SP and Snyder, WH and Lawson, RE}, year={1997}, month={Oct}, pages={1392–1402} }
 @article{yao_arya_davis_main_1997, title={A numerical model of the transport and diffusion of Peronospora tabacina spores in the evolving atmospheric boundary layer}, volume={31}, ISSN={["1352-2310"]}, DOI={10.1016/S1352-2310(96)00181-1}, abstractNote={Abstract Numerical solutions of the diffusion equation of Peronospora tabacina spores from a finite-area source over flat terrain in the evolving convective boundary layer are presented. Temporal variations in the release of spores, atmospheric stability, wind speed, and eddy diffusivity are considered. The model also includes the vertical variations of wind and eddy diffusivity. The model results indicate that ground level concentrations decrease with time as wind speed and eddy diffusivity increase in the evolving convective boundary layer. The loss of P. tabacina spores due to deposition at the surface also decrease with increasing instability and wind speed. Deposition is found to be particularly important close to the source area.}, number={11}, journal={ATMOSPHERIC ENVIRONMENT}, author={Yao, CG and Arya, SP and Davis, J and Main, CE}, year={1997}, month={Jun}, pages={1709–1714} }
 @article{brown_arya_snyder_1997, title={Plume descriptors derived from a non-Gaussian concentration model}, volume={31}, ISSN={["1352-2310"]}, DOI={10.1016/1352-2310(96)00487-6}, abstractNote={Equations for point-source releases are derived from the non-Gaussian solution to the diffusion equation for (l) the first four moments of the vertical concentration distribution (centroid, variance, skew-ness, and kurtosis), (2) the magnitude and downwind location of the maximum ground-level concentration, and (3) the plume advection velocity. Equations are obtained for both ground-level and elevated sources. Where applicable, results are compared to wind-tunnel and field measurements and/or to other less generalized equations.}, number={2}, journal={ATMOSPHERIC ENVIRONMENT}, author={Brown, MJ and Arya, SP and Snyder, WH}, year={1997}, month={Jan}, pages={183–189} }