@article{hasan_larson_mcmonigal_robinson_aiyyer_2024, title={Hemisphere-Dependent Impacts of ENSO and Atmospheric Eddies on Hadley Circulation}, volume={37}, ISSN={["1520-0442"]}, DOI={10.1175/JCLI-D-24-0112.1}, abstractNote={Abstract The variability of the Hadley circulation strength (HCS), crucial to tropical climate variability, is attributed to both oceanic and atmospheric forcings. El Niño-Southern Oscillation (ENSO) and variations in the extratropical upper tropospheric eddies are known drivers of the interannual HCS variability. However, the relative contributions of these oceanic and atmospheric forcings to the hemispheric HCS variability are not well understood. In particular, how much anomalous wind stress-driven ocean dynamics, including ENSO, impact HCS variability remains an open question. To address these gaps, we investigate the drivers of the interannual HCS variability using global coupled model experiments that include or exclude anomalous wind stress-driven ocean circulation variability. We find that the anomalous wind stress-driven ocean circulation variability significantly amplifies HCS variability in the Southern Hemisphere (SH). ENSO is the leading modulator of the SH HCS variability, which offers the potential to improve the predictability of HC-related hydrological consequences. On the other hand, the Northern Hemisphere (NH) HCS variability is predominantly influenced by the eddy-driven internal atmospheric variability with little role for ocean dynamics.We hypothesize that the large eddy variability in the NH and concentrated ENSO-associated heating and precipitation in the SH lead to the hemisphere-dependent differences in the interannual HCS variability.}, number={24}, journal={JOURNAL OF CLIMATE}, publisher={American Meteorological Society}, author={Hasan, Mahdi and Larson, Sarah m. and Mcmonigal, Kay and Robinson, Walter a. and Aiyyer, Anantha}, year={2024}, month={Dec}, pages={6533–6548} }
 @article{fu_hu_zheng_mcmonigal_larson_tian_2024, title={Historical changes in wind-driven ocean circulation drive pattern of Pacific warming}, volume={15}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-024-45677-2}, abstractNote={Abstract The tropical Pacific warming pattern since the 1950s exhibits two warming centers in the western Pacific (WP) and eastern Pacific (EP), encompassing an equatorial central Pacific (CP) cooling and a hemispheric asymmetry in the subtropical EP. The underlying mechanisms of this warming pattern remain debated. Here, we conduct ocean heat decompositions of two coupled model large ensembles to unfold the role of wind-driven ocean circulation. When wind changes are suppressed, historical radiative forcing induces a subtropical northeastern Pacific warming, thus causing a hemispheric asymmetry that extends toward the tropical WP. The tropical EP warming is instead induced by the cross-equatorial winds associated with the hemispheric asymmetry, and its driving mechanism is southward warm Ekman advection due to the off-equatorial westerly wind anomalies around 5°N, not vertical thermocline adjustment. Climate models fail to capture the observed CP cooling, suggesting an urgent need to better simulate equatorial oceanic processes and thermal structures.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Fu, Shuo and Hu, Shineng and Zheng, Xiao-Tong and Mcmonigal, Kay and Larson, Sarah and Tian, Yiqun}, year={2024}, month={Feb} }
 @article{larson_mcmonigal_okumura_amaya_capotondi_bellomo_simpson_clement_2024, title={Ocean Complexity Shapes Sea Surface Temperature Variability in a CESM2 Coupled Model Hierarchy}, volume={37}, ISSN={["1520-0442"]}, DOI={10.1175/JCLI-D-23-0621.1}, abstractNote={Abstract To improve understanding of ocean processes impacting monthly sea surface temperature (SST) variability, we analyze a Community Earth System Model, version 2, hierarchy in which models vary only in their degree of ocean complexity. The most realistic ocean is a dynamical ocean model, as part of a fully coupled model (FCM). The next most realistic ocean, from a mechanically decoupled model (MDM), is like the FCM but excludes anomalous wind stress–driven ocean variability. The simplest ocean is a slab ocean model (SOM). Inclusion of a buoyancy coupled dynamic ocean as in the MDM, which includes temperature advection and vertical mixing absent in the SOM, leads to dampening of SST variance everywhere and reduced persistence of SST anomalies in the high latitudes and equatorial Pacific compared to the SOM. Inclusion of anomalous wind stress–driven ocean dynamics as in the FCM leads to higher SST variance and longer persistence time scales in most regions compared to the MDM. The net role of the dynamic ocean, as an overall dampener or amplifier of anomalous SST variance and persistence, is regionally dependent. Notably, we find that efforts to reduce the complexity of the ocean models in the SOM and MDM configurations result in changes in the magnitude of the thermodynamic forcing of SST variability compared to the FCM. These changes, in part, stem from differences in the seasonally varying mixed layer depth and should be considered when attempting to quantify the relative contribution of certain ocean mechanisms to differences in SST variability between the models.}, number={18}, journal={JOURNAL OF CLIMATE}, author={Larson, Sarah M. and Mcmonigal, Kay and Okumura, Yuko and Amaya, Dillon and Capotondi, Antonietta and Bellomo, Katinka and Simpson, Isla R. and Clement, Amy C.}, year={2024}, month={Sep}, pages={4931–4948} }
 @article{zhang_chen_hu_wang_mcmonigal_larson_2024, title={Summer Westerly Wind Intensification Weakens Southern Ocean Seasonal Cycle Under Global Warming}, volume={51}, ISSN={["1944-8007"]}, DOI={10.1029/2024GL109715}, abstractNote={Abstract Since the 1950s, observations and climate models show an amplification of sea surface temperature (SST) seasonal cycle in response to global warming over most of the global oceans except for the Southern Ocean (SO), however the cause remains poorly understood. In this study, we analyzed observations, ocean reanalysis, and a set of historical and abruptly quadrupled CO 2 simulations from the Coupled Model Intercomparison Project Phase 6 archive and found that the weakened SST seasonal cycle over the SO could be mainly attributed to the intensification of summertime westerly winds. Under the historical warming, the intensification of summertime westerly winds over the SO effectively deepens ocean mixed layer and damps surface warming, but this effect is considerably weaker in winter, thus weakening the SST seasonal cycle. This wind‐driven mechanism is further supported by our targeted coupled model experiments with the wind intensification effects being removed.}, number={14}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Zhang, Yiwen and Chen, Changlin and Hu, Shineng and Wang, Guihua and Mcmonigal, Kay and Larson, Sarah M.}, year={2024}, month={Jul} }
 @article{mcmonigal_larson_hu_kramer_2023, title={Historical Changes in Wind-Driven Ocean Circulation Can Accelerate Global Warming}, volume={50}, ISSN={["1944-8007"]}, DOI={10.1029/2023GL102846}, abstractNote={Abstract Mitigation and adaptation strategies for climate change depend on accurate climate projections for the coming decades. While changes in radiative heat fluxes are known to contribute to surface warming, changes to ocean circulation can also impact the rate of surface warming. Previous studies suggest that projected changes to ocean circulation reduce the rate of global warming. However, these studies consider large greenhouse gas forcing scenarios, which induce a significant buoyancy‐driven decline of the Atlantic Meridional Overturning Circulation. Here, we use a climate model to quantify the previously unknown impact of changes to wind‐driven ocean circulation on global surface warming. Wind‐driven ocean circulation changes amplify the externally forced warming rate by 17% from 1979 to 2014. Accurately simulating changes to the atmospheric circulation is key to improving near‐term climate projections.}, number={4}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={McMonigal, Kay and Larson, Sarah and Hu, Shineng and Kramer, Ryan}, year={2023}, month={Feb} }
 @article{mcmonigal_evans_jones_brett_james_arroyo_gong_miller_kelly_middleton_et al._2023, title={Navigating Gender at Sea}, volume={4}, ISSN={["2576-604X"]}, DOI={10.1029/2023AV000927}, abstractNote={Abstract Fieldwork, including work done at sea, is a key component of many geoscientists' careers. Recent studies have highlighted the pervasive harassment faced by women and LGBTQ+ people during fieldwork. However, transgender and gender diverse (TGD) scientists face obstacles which have not yet been thoroughly examined. We fill this gap by sharing our experiences as TGD people. We have experienced sexual harassment, misconduct, privacy issues, and legal and medical struggles as we conduct seagoing work. In this work, we provide recommendations for individuals, cruise leaders, and institutions for making seagoing work safer for our communities.}, number={4}, journal={AGU ADVANCES}, author={McMonigal, Kay and Evans, Natalya and Jones, Dani and Brett, Jay and James, Reece C. C. and Arroyo, Mar C. C. and Gong, A-bel Y. and Miller, Elizabeth C. C. and Kelly, Colette and Middleton, Jule and et al.}, year={2023}, month={Aug} }
 @article{gunn_mcmonigal_beal_elipot_2022, title={Decadal and Intra-Annual Variability of the Indian Ocean Freshwater Budget}, volume={52}, ISSN={["1520-0485"]}, DOI={10.1175/JPO-D-22-0057.1}, abstractNote={Abstract The global freshwater cycle is intensifying: wet regions are prone to more rainfall, while dry regions experience more drought. Indian Ocean rim countries are especially vulnerable to these changes, but its oceanic freshwater budget—which records the basinwide balance between evaporation, precipitation, and runoff—has only been quantified at three points in time (1987, 2002, 2009). Due to this paucity of observations and large model biases, we cannot yet be sure how the Indian Ocean’s freshwater cycle has responded to climate change, nor by how much it varies at seasonal and monthly time scales. To bridge this gap, we estimate the magnitude and variability of the Indian Ocean’s freshwater budget using monthly varying oceanic data from May 2016 through April 2018. Freshwater converged into the basin with a mean rate and standard error of 0.35 ± 0.07 Sv (1 Sv ≡ 10 6 m 3 s −1 ), indicating that basinwide air–sea fluxes are net evaporative. This balance is maintained by salty waters leaving the basin via the Agulhas Current and fresher waters entering northward across the southern boundary and via the Indonesian Throughflow. For the first time, we quantify seasonal and monthly variability in Indian Ocean freshwater convergence to find amplitudes of 0.33 and 0.16 Sv, respectively, where monthly changes reflect variability in oceanic, rather than air–sea, fluxes. Compared with the range of previous estimates plus independent measurements from a reanalysis product, we conclude that the Indian Ocean has remained net evaporative since the 1980s, in contrast to long-term changes in its heat budget. When disentangling anthropogenic-driven changes, these observations of decadal and intra-annual natural variability should be taken into account.}, number={10}, journal={JOURNAL OF PHYSICAL OCEANOGRAPHY}, author={Gunn, Kathryn L. and McMonigal, K. and Beal, Lisa M. and Elipot, Shane}, year={2022}, month={Oct}, pages={2361–2376} }
 @article{mcmonigal_larson_2022, title={ENSO Explains the Link Between Indian Ocean Dipole and Meridional Ocean Heat Transport}, volume={49}, ISSN={["1944-8007"]}, DOI={10.1029/2021GL095796}, abstractNote={Abstract Indian Ocean meridional heat transport (MHT IO ) drives climate and ecosystem impacts, through changes to ocean temperature. Improved understanding of natural variability in tropical and subtropical MHT IO is needed to contextualize observations and future projections. Previous studies suggest that El Niño‐Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) can drive variability in MHT IO . However, it is unclear whether internally generated IOD can drive variability in MHT IO , or if the apparent relationship between IOD and MHT IO arises because both are modulated by ENSO. Here, we use a model experiment which dynamically removes ENSO to determine the role of internally forced IOD on MHT IO . We find that IOD is not linked to anomalies in MHT IO . Nevertheless, internal atmospheric variability drives significant MHT IO variability. There is little evidence for decadal or multidecadal variability in MHT IO , suggesting this may be a region where an anthropogenic trend rises above the level of internal variability sooner.}, number={2}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={McMonigal, K. and Larson, Sarah M.}, year={2022}, month={Jan} }
 @article{hasan_larson_mcmonigal_2022, title={Hadley Cell Edge Modulates the Role of Ekman Heat Flux in a Future Climate}, volume={49}, ISSN={["1944-8007"]}, DOI={10.1029/2022GL100401}, abstractNote={Abstract In a future climate, the Hadley cell and associated trade easterlies are projected to expand poleward. This projected change in the atmospheric circulation is expected to impact the ocean through changes in the mean sea surface temperature (SST). We also expect implications for the large‐scale SST variability, because near‐surface wind is directly related to two drivers of the SST, that is, turbulent heat flux and anomalous wind‐driven Ekman heat flux. Previous studies show that in the subtropics, anomalous turbulent and Ekman heat fluxes oppose each other, acting to reduce SST variability, whereas, in the midlatitudes, they reinforce each other and enhance SST variability. Through analysis of reanalysis products and Coupled Model Intercomparison Project simulations, we find that the subtropical regions where the fluxes oppose each other are projected to expand poleward in a future climate, following the poleward expansion of the Hadley cell, with potential implications for the amplitude of subtropical SST variability.}, number={17}, journal={GEOPHYSICAL RESEARCH LETTERS}, author={Hasan, Mahdi and Larson, Sarah and McMonigal, Kay}, year={2022}, month={Sep} }
 @article{mcmonigal_gunn_beal_elipot_willis_2022, title={Reduction in Meridional Heat Export Contributes to Recent Indian Ocean Warming}, volume={52}, ISSN={["1520-0485"]}, DOI={10.1175/JPO-D-21-0085.1}, abstractNote={Abstract Since 2000, the Indian Ocean has warmed more rapidly than the Atlantic or Pacific Oceans. Air–sea fluxes alone cannot explain the rapid Indian Ocean warming, which has so far been linked to an increase in temperature transport into the basin through the Indonesian Throughflow (ITF). Here, we investigate the role that the heat transport out of the basin at 36°S plays in the warming. Adding the heat transport out of the basin to the ITF temperature transport into the basin, we calculate the decadal mean Indian Ocean heat budget over the 2010s. We find that heat convergence increased within the Indian Ocean over 2000–19. The heat convergence over the 2010s is of the same order as the warming rate, and thus the net air–sea fluxes are near zero. This is a significant change from previous analyses using transbasin hydrographic sections from 1987, 2002, and 2009, which all found divergences of heat. A 2-yr time series shows that seasonal aliasing is not responsible for the decadal change. The anomalous ocean heat convergence over the 2010s in comparison with previous estimates is due to changes in ocean currents at both the southern boundary (33%) and the ITF (67%). We hypothesize that the changes at the southern boundary are linked to an observed broadening of the Agulhas Current, implying that temperature and velocity data at the western boundary are crucial to constrain heat budget changes.}, number={3}, journal={JOURNAL OF PHYSICAL OCEANOGRAPHY}, author={McMonigal, K. and Gunn, Kathryn L. and Beal, Lisa M. and Elipot, Shane and Willis, Josh K.}, year={2022}, month={Mar}, pages={329–345} }
 @article{mcmonigal_beal_elipot_gunn_hermes_morris_houk_2022, title={The Impact of Meanders, Deepening and Broadening, and Seasonality on Agulhas Current Temperature Variability (vol 50, pg 3529, 2020)}, volume={52}, ISSN={["1520-0485"]}, DOI={10.1175/JPO-D-21-0175.1}, abstractNote={© 2022 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses). Corresponding author: K. McMonigal, ktmcmoni@ncsu.edu}, number={2}, journal={JOURNAL OF PHYSICAL OCEANOGRAPHY}, author={Mcmonigal, K. and Beal, Lisa M. and Elipot, Shane and Gunn, Kathryn L. and Hermes, Juliet and Morris, Tamaryn and Houk, Adam}, year={2022}, month={Feb}, pages={305–311} }