@article {3224146, title = { Wind-relative sampling orientation drives systematic bias in sea-surface microlayer enrichment estimates }, year = {In Preparation}, author = {Li, X. and Solodoch, A. and Rahav, E. and Lehahn, Y.} } @article {3224145, title = {Machine-learning-enabled satellite monitoring of ocean overturning circulation}, year = {In Preparation}, author = {Wei, H. and Stewart, A. and Medvedev, A. and Srinivasan, K. and Solodoch, A. and Manucharyan, G. and Hogg, A. McC.} } @article {3199470, title = {Observations of a Deep-Reaching Submesoscale Eddy}, year = {In Preparation}, author = {Solodoch, A. and Gildor, H. and Toledo, Y. and Barkan, R. and Verma, V. and Fadida, Y. and Lehahn, Y.} } @article {3199468, title = {Ocean Ventilation through the Antarctic Margins}, year = {In Preparation}, author = {Solodoch, A. and Stewart, A.L. and Morrison, A. K. and Hogg, A. McC. and Garabato, A. N.} } @article {3224144, title = {Basin-wide sea-surface observations reveal post-2000 emergence of AMOC weakening}, year = {Submitted}, url = {https://essopenarchive.org/doi/full/10.22541/essoar.15002298/v1}, author = {Medvedev, A. and Wei, H. and Armour, K. and Srinivasan, K. and Solodoch, A. and Stewart, A. and Manucharyan, G., E.} } @article {3197779, title = {Optical Measurement of Oil Slick Thickness Using Active Interferometry}, journal = {Frontiers in Marine Science}, volume = {13}, year = {2026}, abstract = {

Spills of liquid petroleum hydrocarbons are a growing concern worldwide, posing great risks to marine life and community services. Identifying and treating oil spills is operationally and scientifically challenging and compounded by the difficulty in accurately obtaining real-time measurements of the oil thickness slicks. Here, we present a method that allows precise real-time measurement of oil slick thickness, based on active optical interferometry. A series of laboratory experiments with common hydrocarbon pollutant types, namely crude oil and gas condensate, showed that our method yields precise thickness measurements for slicks in the thickness range 0.382 - 23.3 (μm), with an accuracy of 95\%. The proposed spectral-domain active interferometric system enables direct and physically grounded retrieval of oil film thickness without mechanical scanning and without reliance on ambient illumination. In principle, the system can be adapted for deployment at sea, opening the way for real-time,\ in situ\ thickness measurements that will improve oil-spill mitigation efforts and contribute to a deeper understanding of processes at the ocean-atmosphere interface.

}, url = {https://doi.org/10.3389/fmars.2026.1731085}, author = {Obeid, J.P. and Lehahn, Y. and Solodoch, A. and Rahav, E. and Treibitz, T. and Shalabney, A} } @article {3180482, title = {Coastal-to-offshore submesoscale horizontal stirring enhances wintertime phytoplankton blooms in the ultra-oligotrophic Eastern Mediterranean Sea}, journal = {Ocean Science}, volume = {22}, year = {2026}, month = {2 Feb, 2026}, pages = {329-343}, abstract = {

The large seasonal increases in marine photosynthetic organisms {\textendash} i.e., phytoplankton blooms {\textendash} are a ubiquitous oceanic phenomenon that contributes to the removal of carbon dioxide from the atmosphere and supports the growth of larger marine organisms. The underlying mechanisms controlling the intensity and timing of these blooms have been proposed to be dominated by vertical transport and mixing processes that are enhanced at fine-scale frontal and filamental circulations, commonly known as submesoscale currents. Here we show that the winter blooms characteristic of the ultra-oligotrophic waters of the Eastern Mediterranean Sea, which manifest as a seasonal increase in satellite-derived levels of surface chlorophyll, are intensified by enhanced horizontal stirring induced by the submesoscale currents. Using ocean color remote sensing data and high-resolution numerical simulations, we demonstrate that the intensification of submesoscale currents in winter efficiently connect the coastal waters and the ultra-oligotrophic open-sea waters, thereby enriching the latter with chlorophyll-rich waters. A climatological chlorophyll time series comparison between two different regions equidistant to the Nile River Delta indicates that this submesoscale horizontal stirring mechanism accounts for the\ \~{} 24.8 \% larger wintertime increase in surface chlorophyll observed downstream of the Nile Delta. These results shed new light on the processes governing phytoplankton bloom intensity and emphasize the important role of submesoscale horizontal stirring in modulating the marine ecosystem.

}, url = {https://os.copernicus.org/articles/22/329/2026/}, author = {Fadida, Y. and Verma, V. and Barkan, R. and Biton. E. and Solodoch, A. and Lehahn, Y.} } @article {3200233, title = {Statistical analysis of ocean currents in the Eastern Mediterranean}, journal = {EGUsphere}, year = {2025}, url = {https://doi.org/10.5194/egusphere-2025-53}, author = {Ashkenazy, Y. and Gildor, H. and Solodoch, A.} } @article {3199447, title = { Full-depth Reconstruction of Long-Term Meridional Overturning Circulation Variability from Satellite-Measurable Quantities via Machine Learning }, journal = {Journal of Advances in Modeling Earth Systems}, volume = {17}, year = {2025}, abstract = {The meridional overturning circulation (MOC) plays a crucial role in the global distribution of heat, carbon, and other climate-relevant tracers. Monitoring the evolution of MOC is essential for understanding climate variability, yet direct MOC observations are sparse and geographically limited. Although satellite measurements have shown potential for short-term monitoring of the MOC, it remains unclear whether MOC variability on decadal and longer timescales can be detected remotely. In this study, we leverage machine learning to reconstruct long-term MOC variability from satellite-measurable quantities, using climate simulations under pre-industrial conditions. We demonstrate that our proposed non-local dual-branch neural network (DBNN) effectively reconstructs both the strength and vertical structure of the Atlantic MOC (AMOC) and the Southern Ocean MOCs across sub-annual to multi-decadal timescales. Using a neural network interpretation technique, we identify ocean bottom pressure near the western boundary and along dense-water export pathways as the dominant input features for MOC reconstruction. This indicatesthat DBNN{\textquoteright}s predictions can be interpreted as an approximation of geostrophic balance. The DBNN also effectively reconstructs the AMOC in the equatorial region, where geostrophy breaks down. This success is attributed to the capability of DBNN in utilizing latitudinally non-local ocean bottom pressure information and the meridional coherence of AMOC variability. Additionally, the DBNN accurately reconstructs Southern Ocean MOCs using only sea surface height and zonal wind stress as inputs, thereby avoiding reliance on ocean bottom pressure, which is subject to considerable measurement uncertainty in practice. This work demonstrates the possibility of continuous, long-term MOC monitoring using satellite measurements}, url = {https://doi.org/10.1029/2024MS004915}, author = {Wei. H. and Srinivasan, K. and Stewart, A.L. and Solodoch, A. and Manucharyan, G.E. and Hogg, A McC.} } @inbook {3180483, title = {The East Mediterranean boundary current and eddy spectrum}, booktitle = {Book chapter - in "Hod Hayam 2"}, year = {2025}, publisher = {(in Hebrew)}, organization = {(in Hebrew)}, author = {Solodoch, A. and Barkan, R. and Gildor, H.} } @article {3169938, title = {Retrieval of Surface Waves Spectrum from UAV Nadir Video}, journal = {IEEE Transactions on Geoscience and Remote Sensing }, year = {2025}, abstract = {Sea surface wave spectrum measurements are necessary for a host of basic research questions as well as for engineering and societal needs. However, most measurement techniques require great investment in infrastructure and time-intensive deployment techniques. We propose a new approach of wave measurement from standard video footage recorded by low-cost Unmanned Aerial Vehicles (UAV). We address UAV nadir imagery, which are particularly simple to obtain operationally. The method relies on the fact that optical contrast of surface gravity waves is proportional to their steepness. We present a robust methodology of regularized inversion of the optical imagery spectra, resulting in retrieval of the three-dimensional wavenumber-frequency sea surface height spectrum. The system was tested in several sea trials and in different bathymetric depths and sea state conditions. The resulting wave bulk parameters and spectral characteristics are in good agreement with collocated measurements from wave buoys and bottom-mounted acoustic sensors. Simple deployment, mobility, and flexibility in spatial coverage show a great potential of UAVs to significantly enhance the availability of wave measurements.}, url = {https://doi.org/10.1109/TGRS.2025.3536378}, author = {Solodoch, A. and Toledo, Y. and Grigorieva, V. and Lehahn, Y.} } @article {3180481, title = {GRACE Satellite Observations of Antarctic Bottom Water Transport Variability}, journal = {Journal of Geophysical Research - Oceans}, volume = {129}, year = {2024}, abstract = {

Antarctic Bottom Water (AABW) formation and transport constitute a key component of the global ocean circulation. Direct observations suggest that AABW volumes and transport rates may be decreasing, but these observations are too temporally or spatially sparse to determine the cause. To address this problem, we develop a new method to reconstruct AABW transport variability using data from the GRACE (Gravity Recovery and Climate Experiment) satellite mission. We use an ocean general circulation model to investigate the relationship between ocean bottom pressure and AABW: we calculate both of these quantities in the model, and link them using a regularized linear regression. Our reconstruction from modeled ocean bottom pressure can capture 65\%{\textendash}90\% of modeled AABW transport variability, depending on the ocean basin. When realistic observational uncertainty values are added to the modeled ocean bottom pressure, the reconstruction can still capture 30\%{\textendash}80\% of AABW transport variability. Using the same regression values, the reconstruction skill is within the same range in a second, independent, general circulation model. We conclude that our reconstruction method is not unique to the model in which it was developed and can be applied to GRACE satellite observations of ocean bottom pressure. These advances allow us to create the first global reconstruction of AABW transport variability over the satellite era. Our reconstruction provides information on the interannual variability of AABW transport, but more accurate observations are needed to discern AABW transport trends.

}, url = {https://doi.org/10.1029/2024JC020990}, author = {Jeffree, J. and Hogg, A.M.C. and Morrison, A.K and Solodoch, A. and Stewart, A. and McGirr, R.} } @article {3180480, title = {Directional swimming patterns in jellyfish aggregations. In revision.}, journal = {Current Biology}, volume = {34}, year = {2024}, pages = {4033-4038}, abstract = {Having a profound influence on marine and coastal environments worldwide, jellyfish hold significant scientific, economic, and public interest. The predictability of outbreaks and dispersion of jellyfish is limited by a fundamental gap in our understanding of their movement. Although there is evidence that jellyfish may actively affect their position, the role of active swimming in controlling jellyfish movement, and the characteristics of jellyfish swimming behavior, are not well understood. Consequently, jellyfish are often regarded as passively drifting or randomly moving organisms, both conceptually and in process studies. Here we show that the movement of jellyfish is controlled by distinctly directional swimming patterns, which are oriented against the direction of surface gravity waves. Taking a Lagrangian viewpoint from drone videos that allows the tracking of multiple adjacent jellyfish, and focusing the scyphozoan jellyfish Rhopilema nomadica as a model organism, we show that the behavior of individual jellyfish translates into a synchronized directional swimming of the aggregation as a\ whole. Numerical simulations show that this counter-wave swimming behavior results in biased correlated random-walk movement patterns that reduce the risk of stranding, thus providing jellyfish with an adaptive advantage critical to their survival. Our results emphasize the importance of active swimming in regulating jellyfish movement, and open the way for a more accurate representation in model studies, thus improving the predictability of jellyfish outbreaks and their dispersion, and contributing to our ability to mitigate their possible impact on coastal infrastructure and populations.}, url = {https://doi.org/10.1016/j.cub.2024.07.038}, author = {Malul, D. and Berman, H. and Solodoch, A. and Tal. O. and Barak, N. and Mizrahi, G. and Berenshtein, I. and Toledo, Y. and Lotan, T. and Sher, D. and Shavit, U. and Lehahn, Y.} } @article {3180479, title = {The Eastern Mediterranean boundary current: seasonality, stability, and spiral formation}, journal = {Journal of Physical Oceanography}, volume = {54}, year = {2024}, pages = {1971-1989}, abstract = {Seasonal variability and the effect of bottom interaction on the dynamics of the along-slope boundary current flowing around the Levantine basin are investigated using nested high-resolution simulations of the Eastern Mediterranean Sea. The numerical solutions show a persistent boundary current year-round that is ≈ 60 km wide and ≈ 200 m deep. An enstrophy balance diagnostic reveals significant bottom-drag influence on the boundary current, leading to anticyclonic vorticity generation in thin regions along the coast, which in turn become unstable and roll into surface intensified anticyclonic spirals characterized by (1) Rossby numbers. An eddy kinetic energy generation analysis suggests that a mix of baroclinic and barotropic instabilities are likely responsible for the spiral formation. The boundary current and spirals play a crucial role in the cross-shore transport of materials. In winter, the anticyclonic spirals frequently interact and exchange material with the energetic offshore submesoscale flow field. In summer, when the offshore flow structures are relatively less energetic, the spirals remain confined to the boundary current region as they are advected by the boundary current and undergo an upscale kinetic energy (KE) cascade that is manifested in spiral merging, and growth up to 100 km in diameter. In both seasons, a coarse-graining analysis demonstrates that the cross-scale KE fluxes are spatially localized in coherent structures. The upscale KE fluxes typically occur within the spirals, while the downscale KE fluxes are confined to fronts and filaments at spiral peripheries.}, url = {10.1175/JPO-D-23-0207.1}, author = {Verma, V. and Barkan, R. and Solodoch, A. and Gildor, H. and Toledo, Y.} } @article {3180478, title = {Formation of eastern boundary undercurrents via mesoscale eddy rectification}, journal = {Journal of Physical Oceanography}, year = {2024}, abstract = {

Eastern Boundary Upwelling Systems (EBUSs) host equatorward wind-driven near-surface currents overlying poleward subsurface undercurrents. Various previous theories for these undercurrents have emphasized the role of poleward alongshore pressure gradient forces (APF). Energetic mesoscale variability may also serve to accelerate undercurrents via mesoscale stirring of the potential vorticity gradient imposed by the continental slope. However, it remains unclear whether this eddy rectification mechanism contributes substantially to driving poleward undercurrents in EBUS. This study isolates the influence of eddy rectification on undercurrents via a suite of idealized simulations forced either by alongshore winds, with or without an APF, or by randomly-generated mesoscale eddies. It is found that the simulations develop undercurrents with strengths comparable to those found in nature in both wind-forced and randomly forced experiments. Analysis of the momentum budget reveals that the along-isobath undercurrent flow is accelerated by isopycnal advective eddy momentum fluxes and the APF, and retarded by frictional drag. The undercurrent acceleration may manifest as eddy momentum fluxes or as topographic form stress depending on the coordinate system used to compute the momentum budget, which reconciles these findings with previous work that linked eddy acceleration of the undercurrent to topographic form stress. The leading-order momentum balance motivates a scaling for the strength of the undercurrent that explains most of the variance across the simulations. These findings indicate that eddy rectification is of comparable importance to the APF in driving poleward undercurrents in EBUSs, and motivate further work to diagnose this effect in high-resolution models and observations, and to parameterize it in coarse-resolution ocean/climate models.

}, author = {Stewart, A.L. and Wang, Y. and Solodoch, A. and Chen, R. and McWilliams, J.C.} } @article {solodoch2023EMedSpec, title = {Basin scale to Submesoscale variability of the East-Mediterranean Sea upper circulation}, journal = {Journal of Physical Oceanography}, year = {2023}, abstract = {

The East Mediterranean Sea (EMS) circulation has previously been characterized as dominated by gyres, mesoscale eddies, and disjoint boundary currents. We develop nested high resolution EMS numerical simulations to examine circulation variability spectrum with emphasis on the yet unexplored EMS submesoscale. It is identified in model and altimetry data that there is a continuous cyclonic boundary current (BC) encircling the Levantine basin, rather than several disjoint currents. This EMS BC advects eddy chains downstream and is identified as a principle source of regional mesoscale and submesoscale variability. During the seasonal fall to winter mixed layer deepening, energetic submesoscale (O(10 km)) eddies, fronts, and filaments emerge throughout the basin, characterized by O(1) Rossby numbers.\ 

We identify the EMS submesoscale temporal scales as ~1-5 days through spatio-temoral spectral analysis. Mooring data confirms the EMS winter energization of submesoscales with the model-identified times scales. The submesoscale is associated with a ~ k-2 kinetic energy (KE) wavenumber (k) spectral slope, shallower than the quasigeostrophic-like\  ~ k-3 slope diagnosed at summer. The shallowness of the winter spectrum is shown to be due to divergent subinertial motions, consistent with the Boyd 1992 theoretical model rather than surface quasigeostrophy. Using coarse graining, we diagnose a seasonal inverse (forward) KE cascade above (below) 30 km scales due to rotational (divergent) motions, and show that these commence after completion of the fall submesosacle energization. We also show via coarse graining that at scales larger than several 100 kms, the spectrum becomes near constant and a weak forward cascade occurs (from gyre scales) to mesoscales.

}, author = {Solodoch, Aviv and Barkan, Roy and Verma, Vicky and Gildor, Hezi and Toledo, Yaron and Khain, Pavel and Levi, Yoav} } @article {stewart2023EddySatStand, title = {{\textquoteleft}{\textquoteleft}Eddy\&$\#$39;\&$\#$39; Saturation of the Antarctic Circumpolar Current by Standing Waves}, journal = {Journal of Physical Oceanography}, volume = {53}, number = {4}, year = {2023}, pages = {1161{\textendash}1181}, abstract = {It is now well established that changes in the zonal wind stress over the ACC do not lead to changes in its baroclinicity nor baroclinic transport, a phenomenon referred to as {\textquotedblleft}eddy saturation{\textquotedblright}. Previous studies provide contrasting dynamical mechanisms for this phenomenon: on one extreme, changes in the winds lead to changes the efficiency with which transient eddies transfer momentum to the sea floor; on the other, structural adjustments of the ACC{\textquoteright}s standing meanders increase the efficiency of momentum transfer. In this study the authors investigate the relative importance of these mechanisms using an idealized, isopycnal channel model of the ACC. Via separate diagnoses of the model{\textquoteright}s time-mean flow and eddy diffusivity, the authors decompose the model{\textquoteright}s response to changes in wind stress into contributions from transient eddies and the mean flow. A key result is that holding the transient eddy diffusivity constant while varying the mean flow very closely compensates changes in the wind stress, whereas holding the mean flow constant and varying the eddy diffusivity does not. This implies that {\textquotedblleft}eddy saturation{\textquotedblright} primarily occurs due to adjustments in the ACC{\textquoteright}s standing waves/meanders, rather than due to adjustments of transient eddy behavior. The authors derive a quasi-geostrophic theory for ACC transport saturation by standing waves, in which the transient eddy diffusivity is held fixed, and thus provides dynamical insights into standing wave adjustment to wind changes. These findings imply that representing eddy saturation in global models requires adequate resolution of the ACC{\textquoteright}s standing meanders, with wind-responsive parameterizations of the transient eddies being of secondary importance.}, author = {Stewart, Andrew L and Neumann, Nicole K and Solodoch, Aviv} } @article {solodoch2023SomocML, title = {Machine Learning-derived inference of the Meridional Overturning Circulation drom satellite-observable variables in an ocean state estimate}, journal = {Journal of Advances in Modeling Earth Systems}, volume = {15}, number = {4}, year = {2023}, pages = {e2022MS003370}, publisher = {Wiley Online Library}, abstract = {

The oceanic Meridional Overturning Circulation (MOC) plays a key role in the climate system, and monitoring its evolution is a scientific priority. Monitoring arrays have been established at several latitudes in the Atlantic Ocean, but other latitudes and oceans remain unmonitored for logistical reasons. This study explores the possibility of inferring the MOC from globally-available satellite measurements via machine learning (ML) tecchniques, using the ECCOV4 state estimate as a test bed. The methodological advantages of the present approach include the use purely of available satellite data, its applicability to multiple basins within a single ML framework, and the ML model simplicity (a feed-forward fully connected neural network with small number of neurons). The ML model exhibits high skill in MOC reconstruction in the Atlantic, Indo-Pacific, and Southern Oceans. The approach achieves a higher skill in predicting the model Southern Ocean abyssal MOC than has previously been achieved via a dynamically-based approach. The skill of the model is quantified as a function of latitude in each ocean basin, as well as a function of the time scale of MOC variability. We find that ocean bottom pressure generally has the highest reconstruction skill potential, followed by zonal wind stress. We addition ally test which combinations of variables are optimal. Furthermore, ML interpretabil ity techniques are used to show that high reconstruction skill in the Southern Ocean is mainly due to (NN processing of) bottom pressure variability at a few prominent bathy metric ridges. Finally, the potential for reconstructing MOC strength estimates from real satellite measurements is discussed.

}, author = {Solodoch, Aviv and Stewart, Andrew L and McC. Hogg, Andrew and Manucharyan, Georgy E} } @article {solodoch2022AabwPaths, title = {How does Antarctic Bottom Water cross the Southern Ocean?}, journal = {Geophysical Research Letters}, volume = {49}, number = {7}, year = {2022}, pages = {e2021GL097211}, publisher = {Wiley Online Library}, abstract = {Antarctic Bottom Water (AABW), which fills the global ocean abyss, is derived from dense water that forms in several distinct Antarctic shelf regions. Previous modeling stud ies have reached conflicting conclusions regarding export pathways of AABW across the Southern Ocean and the degree to which AABW originating from distinct source regions are blended during their export. This study addresses these questions using passive tracer deployments in a 61-year global high-resolution (0.1 degree) ocean/sea-ice simulation. Two distinct export {\textquotedblleft}conduits{\textquotedblright} are identified: Weddell Sea- and Prydz Bay-sourced AABW are blended together and exported mainly to the Atlantic and Indian Oceans, while Ross Sea and Adelie Land-sourced AABW are exported mainly to the Pacific Ocean. Northward transport of each tracer occurs almost exclusively (\>90\%) within a single conduit. These findings imply that regional changes in AABW production may impact the three-dimensional structure of the global overturning circulation.}, author = {Solodoch, A and Stewart, AL and Hogg, A McC and Morrison, AK and Kiss, AE and Thompson, AF and Purkey, SG and Cimoli, L} } @article {solodoch2021VortexInValley, title = {Formation of anticyclones above topographic depressions}, journal = {Journal of Physical Oceanography}, volume = {51}, number = {1}, year = {2021}, pages = {207{\textendash}228}, abstract = {Long-lived anticyclonic eddies (ACs) have been repeatedly observed over several North Atlantic basins characterized by bowl-like topographic depressions. Motivated by these previous findings, the authors conduct numerical simulations of the spin-down of eddies initialized in idealized topographic bowls. In experiments with 1 or 2 isopycnal layers, it is found that a bowl-trapped AC is an emergent circulation pattern under a wide range of parameters. The trapped AC, often formed by repeated mergers of ACs over the bowl interior, is characterized by anomalously low potential vorticity (PV). Several PV segregation mechanisms that can contribute to the AC formation are examined. In one-layer experiments, the dynamics of the AC are largely determined by a nonlinearity parameter () that quantifies the vorticity of the AC relative to the bowl{\textquoteright}s topographic PV gradient. The AC is trapped in the bowl for low  . 1, but for moderate values (0.5 .  . 1) partial PV segregation allows the AC to reside at finite distances from the center of the bowl. For higher  \& 1, eddies freely cross the topography and the AC is not confined to the bowl. These regimes are characterized across a suite of model experiments using  and a PV homogenization parameter. Two-layer experiments show that the trapped AC can be top- or bottom-intensified, as determined by the domain-mean initial vertical energy distribution. These findings contrast with previous theories of mesoscale turbulence over topography that predict the formation of a prograde slope current, but do not predict a trapped AC.}, author = {Solodoch, Aviv and Stewart, Andrew L and McWilliams, James C} } @article {stewart2021HfAabwVar, title = {High-frequency fuctuations in Antarctic Bottom water transport driven by Southern Ocean winds}, journal = {Geophysical Research Letters}, volume = {48}, number = {17}, year = {2021}, pages = {e2021GL094569}, publisher = {Wiley Online Library}, abstract = {
Northward flow of Antarctic Bottom Water (AABW) across the Southern Ocean comprises a key component of the global overturning circulation. Yet AABW transport remains poorly constrained by observations and state estimates, and there is presently no means of directly monitoring any component of the Southern Ocean overturning. However, AABW flow is dynamically linked to Southern Ocean surface circulation via the zonal momentum balance, offering potential routes to indirect monitoring of the transport. Exploiting this dynamical link, this study shows that wind stress (WS) fluctuations drive large AABW transport fluctuations on time scales shorter than E2 years, which comprise almost all of the transport variance. This connection occurs due to differing time scales on which topographic and interfacial form stresses respond to wind variability, likely associated with differences in barotropic versus baroclinic Rossby wave propagation. These findings imply that AABW transport variability can largely be reconstructed from the surface WS alone.}, author = {Stewart, Andrew L and Chi, Xiaoyang and Solodoch, Aviv and Hogg, Andrew McC} } @article {stewart2021GyreBotTorque, title = {On the role of bottom pressure torques in wind-driven gyres}, journal = {Journal of Physical Oceanography}, volume = {51}, number = {5}, year = {2021}, pages = {1441{\textendash}1464}, abstract = {Previous studies have concluded that the wind-input vorticity in ocean gyres is balanced by bottom pressure torques (BPT), when integrated over latitude bands. However, the BPT must vanish when integrated over any area enclosed by an isobath. This constraint raises ambiguities regarding the regions over which BPT should close the vorticity budget, and implies that BPT generated to balance a local wind stress curl necessitates the generation of a compensating, non-local BPT and thus non-local circulation. This study aims to clarify the role of BPT in wind-driven gyres using an idealized isopycnal model. Experiments performed with a single-signed wind stress curl in an enclosed, sloped basin reveal that BPT balances the winds only when integrated over latitude bands. Integrating over other, dynamically-motivated definitions of the gyre, such as barotropic streamlines, yields a balance between wind stress curl and bottom frictional torques. This implies that bottom friction plays a non-negligible role in structuring the gyre circulation. Non-local bottom pressure torques manifest in the form of along-slope pressure gradients associated with a weak basin-scale circulation, and are associated with a transition to a balance between wind stress and bottom friction around the coasts. Finally, a suite of perturbation experiments is used to investigate the dynamics of BPT. To predict the BPT, the authors extend previous theory that describes propagation of surface pressure signals from the gyre interior toward the coast along planetary potential vorticity contours. This theory is shown to agree closely with the diagnosed contributions to the vorticity budget across the suite of model experiments.}, author = {Stewart, Andrew L and McWilliams, James C and Solodoch, Aviv} } @article {solodoch2020DensityCurrVsIGW, title = {Observations of shoaling density current regime changes in internal wave interactions}, journal = {Journal of Physical Oceanography}, volume = {50}, number = {6}, year = {2020}, pages = {1733{\textendash}1751}, abstract = {We present in-situ and remote observations of a Mississippi plume front in the Louisiana bight. The plume propagated freely across the bight, rather than as a coastal current. The observed cross-front circulation pattern is typical of density currents, as are the small width (≈ 100m) of the plume front, and the presence of surface frontal convergence. A comparison of observations with stratified density current theory is conducted. Additionally, subcritical to supercritical transitions of frontal propagation speed relative to Internal-Gravity wave (IGW) speed are demonstrated to occur. That is in part due to IGW speed reductions due to decreasing bottom depths as the front approaches the shore. Theoretical steady state density current propagation speed is in good agreement with the observations in the critical and supercritical regimes but not in the inherently unsteady subcritical regime. The latter may be due to interaction of IGW with the front, an effect previously demonstrated only in laboratory and numerical experiments. In the critical regime, finite-amplitude IGWs form and remain locked to the front. A critical to supercritical transition eventually occurs as the ambient conditions change in frontal propagation, after which IGWs are not supported at the front. The subcritical (critical) to critical (supercritical) transition is related to Froude number ahead (under) the front, consistently with theory. Finally, we find that the front-locked IGW (critical) regime is itself dependent on significant nonlinear speed enhancement of the IGW by their growth to finite amplitude at the front.}, author = {Solodoch, Aviv and Molemaker, Jeroen M and Srinivasan, Kaushik and Berta, Maristella and Marie, Louis and Jagannathan, Arjun} } @book {solodoch2020PhD, title = {Topographic effects on mesoscale ocean circulation}, year = {2020}, publisher = {PhD Dissertation, University of California, Los Angeles}, organization = {PhD Dissertation, University of California, Los Angeles}, author = {Solodoch, Aviv} } @article {solodoch2020DwbcLeak, title = {Why does the Deep Western Boundary Current \&$\#$39;\&$\#$39;leak\&$\#$39;\&$\#$39; around flemish cap?}, journal = {Journal of Physical Oceanography}, volume = {50}, number = {7}, year = {2020}, pages = {1989{\textendash}2016}, publisher = {American Meteorological Society}, abstract = {The southward flowing deep limb of the Atlantic Meridional Overturning Circulation is comprised of both the Deep Western Boundary Current (DWBC) and interior pathways. The latter are fed by {\textquotedblleft}leakiness{\textquotedblright} from the DWBC in the Newfoundland Basin. However, the cause of this leakiness has not yet been explored mechanistically. Here the statistics and dynamics of the DWBC leakiness in the Newfoundland Basin are explored using two float data sets and a high-resolution numerical model. The float leakiness around Flemish Cap is found to be concentrated in several areas ({\textquotedblleft}hotspots{\textquotedblright}) that are collocated with bathymetric curvature and steepening. Numerical particle advection experiments reveal that the Lagrangian mean velocity is offshore at these hotspots, while Lagrangian variability is minimal locally. Furthermore, model Eulerian-mean streamlines separate from the DWBC to the interior at the leakiness hotspots. This suggests that the leakiness of Lagrangian particles is primarily accomplished by an Eulerian-mean flow across isobaths, though eddies serve to transfer around 50\% of the Lagrangian particles to the leakiness hotspots via chaotic advection, and rectified eddy transport accounts for around 50\% of the offshore flow along the Southern Face of Flemish Cap. Analysis of the model{\textquoteright}s energy and potential vorticity budgets suggests that the flow is baroclinically unstable after separation, but that the resulting eddies induce modest modifications of the mean potential vorticity along streamlines. These results suggest that mean uncompensated leakiness occurs mostly through inertial separation, for which a scaling analysis is presented. Implications for leakiness of other major boundary current systems are discussed.}, author = {Solodoch, Aviv and McWilliams, James C and Stewart, Andrew L and Gula, Jonathan and Renault, Lionel} } @article {solodoch2016BcInstablTorus, title = {Baroclinic instability of axially symmetric flow over sloping bathymetry}, journal = {J. Fluid Mech.}, volume = {799}, year = {2016}, pages = {265{\textendash}296}, publisher = {Cambridge University Press}, abstract = {Observations and models of deep ocean boundary currents show that they exhibit complex variability, instabilities and eddy shedding, particularly over continental slopes that curve horizontally, for example around coastal peninsulas. In this article the authors investigate the source of this variability by characterizing the properties of baroclinic instability in mean flows over horizontally curved bottom slopes. The classical 2-layer quasi-geostrophic solution for linear baroclinic instability over sloping bottom topography is extended to the case of azimuthal mean flow in an annular channel. To facilitate comparison with the classical straight channel instability problem of uniform mean flow, the authors focus on comparatively simple flows in an annulus, namely uniform azimuthal velocity and solid-body rotation. Baroclinic instability in solid-body rotation flow is analytically analogous to the instability in uniform straight channel flow due to several identical properties of the mean flow, including vanishing strain rate and vorticity gradient. The instability of uniform azimuthal flow is numerically similar to straight channel flow instability as long as the mean barotropic azimuthal velocity is zero. Nonzero barotropic flow generally suppresses the instability via horizontal curvatureinduced strain and Reynolds stresses work. An exception occurs when the ratio of the bathymetric to isopycnal slopes is close to (positive) one, as is often observed in the ocean, in which case the instability is enhanced. A non-vanishing mean barotropic flow component also results in a larger number of growing eigenmodes and in increased non-normal growth. The implications of these findings for variability in deep western boundary currents are discussed.}, author = {Solodoch, Aviv and Stewart, Andrew L and McWilliams, James C} } @article {solodoch2010WISHE2MJO, title = {Excitation of intraseasonal variability in the equatorial atmosphere by Yanai wave groups via WISHE-induced convection}, journal = {Journal of the Atmospheric Sciences}, volume = {68}, year = {2010}, pages = {210--222}, abstract = {

A mechanism is presented, based on multiscale interactions via nonlinear wind-induced surface heat exchange (WISHE), that produces eastward-propagating, intraseasonal convective anomalies in the tropical atmosphere. Simulations of convectively coupled disturbances are presented in two intermediate-complexity atmospheric models. One is a shallow water model with a simple WISHE-motivated heating term. The other model is also based on a first baroclinic mode but has an additional prognostic equation for humidity and a simple representation of moist convection based on a quasi-equilibrium approximation. In spite of many differences between the models, they robustly produce a coherent signal in westerly winds and convection that travels eastward at 4{\textendash}10 m s-1. It is shown here that this slow signal is a forced response to an eastward-propagating Yanai (mixed Rossby{\textendash}gravity) wave group. The response takes the form of a forced Kelvin wave that is driven nonlinearly, via WISHE, by meridional wind anomalies of the Yanai wave group and that travels considerably more slowly than the free convectively coupled Kelvin waves in these models. The Yanai waves are destabilized in the models used here by WISHE in the presence of mean easterlies, but more generally they could also be excited by stratiform instability in the absence of mean easterlies so that the mechanism described here could also operate without mean easterlies. Similarities to and differences from the Madden{\textendash}Julian oscillation (MJO) and convectively coupled tropical waves are discussed.

}, url = {https://doi.org/10.1175/2010JAS3564.1}, author = {Solodoch, Aviv and Boos, William and Kuang, Zhiming and Tziperman, Eli} }