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OS4.3

Physical Processes of Ocean-Atmosphere Exchange

This session welcomes submissions on new insights into the physical processes at the air-sea interface and their role in ocean-atmosphere exchange of heat, gas, momentum, freshwater, and aerosols.
Presentations based on field or satellite observations, numerical models, or theoretical contributions are welcome.

Examples of processes include solar radiation-induced diurnal warming, rain-induced cool and fresh lenses, and processes controlling the formation and properties of the surface microlayer.
Additional focus is on gustiness associated with convection in the atmospheric boundary layer and evaporative cold pools. Further focus is on air-sea interactions in polar regions, in particular related to cold air outbreaks, including the role of sea ice and the effect of leads. Air-sea interaction related to surface temperature and salinity fronts, as well as oceanic meso- and sub-mesoscale dynamics, are also of great interest. Studies considering the variability of biogeochemical properties related to air-sea processes will also be considered.

Co-organized by AS2
Convener: Brian Ward | Co-conveners: Hugo Bellenger, Kyla Drushka, Ilan Koren, Thomas Spengler
Presentations
| Mon, 23 May, 15:55–18:10 (CEST)
 
Room 1.15/16

Mon, 23 May, 15:10–16:40

Chairpersons: Brian Ward, Hugo Bellenger

15:55–16:02
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EGU22-115
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ECS
Johan Edholm et al.

Atmospheric rivers (ARs) dominate moisture transport globally, accounting for 90% of poleward atmospheric freshwater transport in the mid-to-high latitudes while only covering 10% of the surface. Yet, it is unknown what impact ARs have on the surface ocean buoyancy in the high latitudes. This is explored using high-resolution surface observations from a Wave glider deployed at a site in the Southern Ocean (54°S, 0°E) during austral summer. During this time (19 December 2018 - 12 February 2019, 55 days) we show that when ARs combine with storms over this area, the associated precipitation is enhanced significantly (162%). AR-induced precipitation events provided a major source of surface ocean buoyancy equivalent to the input of surface heat fluxes on a daily timescale. Cumulatively, ARs account for 44% of the summer precipitation equating to 9% of surface buoyancy gain. These results show that AR variability is a previously unaccounted driver of Southern Ocean surface buoyancy that may ultimately impact upper ocean water mass transformation and the dynamics of the ocean surface boundary layer.

How to cite: Edholm, J., Swart, S., du Plessis, M., and Nicholson, S.-A.: Glider observed surface buoyancy forcing from an atmospheric river in the Weddell Sea during austral summer 2019, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-115, https://doi.org/10.5194/egusphere-egu22-115, 2022.

16:02–16:09
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EGU22-393
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ECS
David Hagman

The icebreaker R/V SA Agulhas II spent 3 months (December-Feb) in the open ocean (35 days) and sea ice (40 days) collecting atmospheric and oceanographic variables required for calculating momentum, sensible heat, and latent heat fluxes. In addition, both longwave and shortwave radiative fluxes were measured by radiometers to provide a full air-sea heat flux budget. These observations were compared against the commonly-used reanalysis product ERA5 to evaluate surface heat flux components in both the Southern Ocean sea ice and open ocean regions during austral summer to better understand air-sea interactions in the region. Both sensible and latent heat fluxes had significant short-term events (less than a day) that reduced the daily mean by 13% and 3% respectively. Wind speed, air temperature, shortwave, latent and sensible heat fluxes were all underestimated by ERA5 in sea ice, while SST and longwave were overestimated. Ship-based sensible heat flux in sea ice exhibited a diurnal phasing with a minimum ocean heat loss during mid-day (-25 Wm⁻². ERA5 had a reversed diurnal phase with a maximum heat loss in mid-day (-23 Wm⁻²). Ship-based latent heat flux varied little (±3.6 Wm⁻² daily range), whereas ERA5 had a diurnal phase similar to sensible heat flux  (-62 Wm⁻²).The total biases in the neat heat flux show that ERA5 underestimates the net heat flux by 65 Wm⁻² in sea ice due to the difference in diurnal phases of turbulent fluxes. Here, the sensible and latent heat flux are underestimated by 34 Wm⁻² and 20 Wm⁻² respectively. In the open ocean, turbulent fluxes agree well between ERA5 and ship observations (<10 Wm⁻² difference). Shortwave and longwave (radiative fluxes) are consistently biased in estimations by ERA5 in both sea ice and open ocean, possibly due to parameterization of clouds. Longwave radiation is overestimated by 28 Wm⁻² by ERA5 in both regions, shortwave is cold biased (underestimated) by 25 Wm⁻² in sea ice and warm biased (overestimated) by 46 Wm⁻² in the open ocean. This in situ evaluation of heat flux components is highly valuable for further improving our understanding of heat fluxes in the Southern Ocean.

How to cite: Hagman, D.: Unraveling the uncertainties of bulk-derived heat fluxes: a case study for the Southern Ocean, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-393, https://doi.org/10.5194/egusphere-egu22-393, 2022.

16:09–16:16
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EGU22-695
Achim Wirth

  

The input of mechanical power to the ocean due to the surface wind-stress, in regions which correspond to different regimes of ocean dynamics, is considered using data from satellites observations. Its dependence on the coarse-graining range of the atmospheric and oceanic velocity in space from 0.5° to 10° and time from 6h to 40 days is determined.

 

In the area of the Gulf Stream and the Kuroshio extensions the dependence of the power-input on space-time coarse-graining varies over tenfold for the coarse-graining considered. It decreases over twofold for the Gulf Stream extension and threefold for the Kuroshio extension, when the coarse-graining length-scale passes from a few degrees to 0.5° at a temporal coarse-graining scale of a few days. It increases over threefold in the Gulf Stream and the Kuroshio extensions when the coarse-graining passes from several days to 6h at a spatial coarse-graining of a few degrees. The power input is found to increase monotonically with shorter coarse-graining in time. Its variation with coarse-graining in space has no definite sign. Results show that including the dynamics at scales below a few degrees reduces considerably the power input by air-sea interaction in regions ofstrongly non-linear ocean currents. When the ocean velocities are not considered in the shear calculation the power-input is considerably (up to threefold) increased. The dependence of the power input on coarse-graining in space and time is close to being multiplicatively separable in all regions and for most of the coarse-graining domain considered.

How to cite: Wirth, A.: Determining the dependence of the power supply to the ocean on the length and time scales of the dynamics between the meso-scale and the synoptic-scale, from satellite data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-695, https://doi.org/10.5194/egusphere-egu22-695, 2022.

16:16–16:23
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EGU22-1161
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ECS
Thomas Wilder et al.

Including the ocean surface current in relative wind stress is known to damp mesoscale eddies through a negative wind power input. This is thought to have potential ramifications for eddy longevity. Here, we study the spin-down of a baroclinic anticyclonic eddy subject to absolute and relative wind stress forcing by employing an idealised high-resolution numerical model. To assess the effect of relative wind stress on the eddy, we examine wind-induced vertical motions and energetics. Results from this study show that relative wind stress damps eddy kinetic energy (EKE) at the eddy’s surface. However, relative wind stress also induces additional vertical motions, in the form of Ekman pumping, that increases baroclinic conversion i.e., a conversion of potential to kinetic energy. When horizontally integrated, this additional baroclinic conversion by relative wind stress is positive throughout the eddy water column. The positive baroclinic conversion in the lower depths of the eddy leads to an increase in deep EKE, relative to the absolute wind stress case. In fact, over the eddy volume, the damping of EKE by relative wind stress is offset by this conversion of energy. Moreover, this conversion turns out to dominate any damping by wind during the later stages of eddy lifetime. A scaling analysis of relative wind stress-induced baroclinic conversion and relative wind stress damping also confirms these numerical findings, showing that energy conversion is greater than wind damping. Overall, this highlights the complexities of ocean-atmosphere interactions at the mesoscale, and points to the need for further study in this area.

How to cite: Wilder, T., Zhai, X., Joshi, M., and Munday, D.: The Response of a Baroclinic Anticyclonic Mesoscale Eddy to Relative Wind Stress Forcing, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1161, https://doi.org/10.5194/egusphere-egu22-1161, 2022.

16:23–16:30
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EGU22-2527
Mingxi Yang et al.

The flux of CO2 between the atmosphere and the ocean is often estimated as the air–sea gas concentration difference multiplied by the gas transfer velocity (K660). The first order driver for K660 over the ocean is wind through its influence on near surface hydrodynamics. However, field observations have shown substantial variability in the wind speed dependencies of K660. During a ~ 11,000 km long Southern Ocean transect, we measured K660 with the eddy covariance technique.  In parallel, we made a novel measurement of the gas transfer efficiency (GTE) based on partial equilibration of CO2 using a Segmented Flow Coil Equilibrator system. GTE varied by 20% during the transect, was distinct in different water masses, and related to K660. At a moderate wind speed of 7 m s−1, K660 associated with high GTE exceeded K660 with low GTE by 30% in the mean. The sensitivity of K660 towards GTE was stronger at lower wind speeds and weaker at higher wind speeds. Naturally-occurring organics in seawater, some of which are surface active, are likely the cause of the variability in GTE and in K660. To investigate this further, we perform further laboratory experiments to assess the effects of surfactant concentration and water temperature on GTE.

How to cite: Yang, M., Smyth, T., Kitidis, V., Brown, I., Wohl, C., Yelland, M., and Bell, T.: Natural variability in air–sea gas transfer efficiency of CO2 , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2527, https://doi.org/10.5194/egusphere-egu22-2527, 2022.

Mon, 23 May, 17:00–18:30

Chairpersons: Kyla Drushka, Ilan Koren, Thomas Spengler

17:00–17:07
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EGU22-3266
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ECS
Yuan Cao et al.

A mixing length theory which considers the impact of TC characters and upper ocean stratification, is used to estimate the tropical cyclone (TC) induced diapycnal diffusivity, and investigate the trend, interannual and interdecadal variability of TC-induced diapycnal diffusivity in the globe and each basin. The annual mean climatology of the TC-induced diapycnal diffusivity is consistent with previous research, with maximum values in the Western North Pacific (WP) ranging from 0.05 cm2/s up to 1 cm2/s. The trends of TC-induced diapycnal diffusivity exhibit great inter-basin differences, which are not only related with TC itself, but also the ocean stratification. On the interannual timescales, El Niño and Southern Oscillation (ENSO) can modulate the variability of TC-induced diapycnal diffusivity in the globe by regulating the ocean stratification rather than TC intensity, because the impacts of ENSO on TC intensity in each basin cancel out each other. As for each basin, ENSO can affect TC-induced diapycnal diffusivity mainly by regulating the variability of TC intensity. In addition, the relationship of TC-induced diapycnal diffusivity with dominant climate modes such as Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO) may be interactive on the interdecadal timescales, especially in the areas which are significantly influenced by PDO and NAO, such as WP, Eastern North Pacific and North Atlantic. We anticipate that these results can provide insights into the variability and physical mechanisms of TC-induced diapycnal mixing.

How to cite: Cao, Y., Wang, X., and Shao, C.: Global Estimate of Tropical Cyclone-Induced Diapycnal Mixing and Its Links to Climate Variability, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3266, https://doi.org/10.5194/egusphere-egu22-3266, 2022.

17:07–17:14
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EGU22-4142
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ECS
Mohamed Kaouah et al.

Tropical Cyclones (TC) are strongly coupled systems as the underlying warm ocean serves as an energy source for the TC while the strong cyclonic winds modify the ocean state. Good predictions of the TC development are dependant on our knowledge of the ocean heat content which may favor or inhibit the TC. Understanding how the ocean stratification evolves at the same time the TC does is thus crucial to improve TC forecasts.

The 2018-2019 cyclonic season of the South Western Indian Ocean was active and saw the development of nine intense TCs. These cyclones went through regions with different oceanic properties in terms of stratification and heat content. The aim of this study is to understand how such ocean properties affect TC evolution.

To this end, we conducted several idealized simulations of TC using the same atmospheric state but with different oceanic profiles (temperature, salinity) derived from 5-month MERCATOR analysis data (from November 2018 to March 2019). The experiments were conducted using a state of the art coupled modelling system with CROCO (for the ocean) and Meso-NH (for the atmosphere) models with a grid spacing of 4 km.

The TC lifecycle (i.e intensity, structure) as well as the ocean response (i.e. sea surface cooling, advection and mixing processes) are investigated with a particular emphasis on the heat budget analysis. We found that a rapid TC intensification phase occurred due to the warm oceanic surface layers (the first 40 meters) and a strong decaying phase occurred due to the cooler underlying ocean. Moreover we highlight the chronology of the cooling processes in the oceanic mixed layer and the importance of the advection processes within it, which are then relayed by vertical mixing.

How to cite: Kaouah, M., Lee, K.-O., Bielli, S., and Lapeyre, G.: Oceanic restratification processes associated with tropical cyclone intensification, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4142, https://doi.org/10.5194/egusphere-egu22-4142, 2022.

17:14–17:21
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EGU22-4167
Thomas Spengler and Clemens Spensberger

Modeling air-sea interactions during cold air outbreaks poses a major challenge because of the vast range of scales and physical processes involved. Using the WRF model, we investigate the sensitivity of air mass transformation in an idealised cold air outbreak across a lead-fractured sea ice to (a) lead width, (b) lead orientation relative to the atmospheric flow, and (c) model resolution.

The extent to which leads are resolved in WRF strongly affects the overall air-sea heat exchange. In fact, even the direction of the heat exchange is dependent on model resolution. Further, the dependence of the overall heat exchange on model resolution is strongly non-linear, with the worst representation of the heat exchange through leads occuring when they are just about to become resolved by the model grid. In addition, the orientation of the leads relative to the atmospheric flow affects the air-sea heat exchange. Heat exchange is least effective when the leads are oriented perpendicular to the atmospheric flow.

How to cite: Spengler, T. and Spensberger, C.: Sensitivity of air-sea heat exchange to lead width and orientation as well as model resolution, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4167, https://doi.org/10.5194/egusphere-egu22-4167, 2022.

17:21–17:28
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EGU22-6257
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ECS
Ehud Strobach et al.

On January 8, 2020, an extreme storm event took place in the Eastern Mediterranean Sea, during which 100-130mm of rain fell in the northern part of Israel in one day. The heavy precipitation event resulted in seven deaths and damages to homes, vehicles, and infrastructure. At the same time, about 100km to the west of northern Israel, the sea was characterized by a mesoscale eddy with a warm core. In recent years, it was established that small-scale sea features affect the atmosphere above and synoptic-scale circulation patterns, including long-term rainfall. However, it is still unclear how these features may affect the propagation and intensity of individual storms, such as the January 8, 2020 storm event.

Recently, the WRF (The Weather Research and Forecasting) atmospheric model was coupled with the ocean model MITgcm (MIT general circulation model). The coupled model was named the SKRIPS (Scripps–KAUST Regional Integrated Prediction System) model. The two SKRIPS model components (WRF and MITgcm) are well tested at high resolutions, and the regionality of the coupled model allows us to isolate local features while maintaining the large-scale circulation as observed.

In this talk, I will present results from a high-resolution (~5km) coupled atmosphere-ocean regional simulation using the SKRIPS model performed during the January 8, 2020 event. The importance of the sea eddy in determining the storm intensity and propagation will be discussed, elaborating on the role of air-sea coupling and the model resolution. Understanding the effect of such small-scale sea features on extreme atmospheric events may improve their representation in weather and climate models, extending models prediction skill.

How to cite: Strobach, E., Klein, P., and Ziv, B.: The role of a Mediterranean Sea eddy in the January 2020 flooding in Israel, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6257, https://doi.org/10.5194/egusphere-egu22-6257, 2022.

17:28–17:35
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EGU22-6772
Yonglin Huang

The impact of oceanic mesoscale eddies on sensible heat fluxes and related air-sea variables in the South China Sea, an eddy-active area, is investigated by using 20 years (2000–2019) of remotely sensed sea surface temperature, mesoscale eddy trajectories atlas with satellite altimetry and a high-resolution air-sea heat flux product. Composite analyses based on 623 cyclonic eddies (CEs) and 508 anticyclonic eddies (AEs) revealed that CEs (AEs) eddies tend to decrease (increase) the surface sensible heat fluxes over the eddies with maximum mean anomalies of -5.79W/m2 (4.36 W/m2), cool (warm) the sea surface and cause surface winds to decelerate (accelerate). The composite results of fluxes and variables anomalies are stronger near the eddies centres, but the extrema of anomalies locate westward relative to the CEs (AEs) cores due to the dominant moving direction of eddies in this region. The dynamic analysis of multiple mesoscale eddies tracks demonstrates the sustained and delayed response of the marine atmospheric boundary layer to oceanic eddies. The reduction (increase) of sensible heat flux over CEs (AEs) tracks reaches the maximum after CEs (AEs) pass 2 (3) days and averagely last for more than one week. In addition, the effect of mesoscale eddies on sensible heat fluxes increases with eddy amplitude and radius and negatively correlates with their moving speed. The results also show remarkable seasonal variations of CEs (AEs) influence on fluxes and variables anomalies, stronger in winter and weaker in summer.

How to cite: Huang, Y.: The signature of air-sea sensible heat fluxes associated with mesoscale eddies in the South China Sea, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6772, https://doi.org/10.5194/egusphere-egu22-6772, 2022.

17:35–17:42
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EGU22-7473
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ECS
Andrew Smith et al.

Air-sea gas exchange has up-scale ramifications for global climate and ocean biogeochemistry that are of paramount relevance. Gas transfer velocity (k) measurements or appropriate parameterizations for them are required to quantify the fluxes and budgets of the important trace gases (e.g., CO2, DMS, and CH4). Where gas flux and concentration gradients are not explicitly measured, k is subdivided into diffusive and bubble-mediated components – each parameterized. Although diffusive transfer velocity, ks , has been well-described by power-law relationships involving the Schmidt number Sc, large variability exists in parameterizations for bubble-mediated gas transfer velocity, kb. Since kb is driven primarily by entrainment of gases through wave breaking, the uncertainty is acutely problematic at high winds where gas flux measurements are scarce. To address the paucity of such data, the High Wind Gas Exchange Study (HiWinGS) directly calculated gas transfer velocity of CO2 (kCO2) from flux and concentration gradient measurements taken in the Labrador Sea from October 9 – November 13, 2013, where 10-meter neutral wind speeds ranged between 1.8 – 25.2 m s-1. We use these data to validate a novel gas transfer velocity parameterization constructed using output from a wave hindcast obtained with the spectral wave model (ecWAM) forced with the European Centre for Medium-Range Weather Forecasts (ECMWF) 5th Generation Reanalysis (ERA5). Our parameterisation combines a diffusive term based on wind speed and Sc, and a bubble-mediated term based on gas solubility, wave age, and wave breaking energy dissipation rate to capture gas transfer velocity. We compare our results to common wind-speed-only parameterisations and more recent sea-state based relationships.

How to cite: Smith, A., Callaghan, A., and Bidlot, J.-R.: Parameterising CO2 air-sea gas transfer with wave breaking energy dissipation rate, sea state, and wind speed, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7473, https://doi.org/10.5194/egusphere-egu22-7473, 2022.

17:42–17:49
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EGU22-9971
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ECS
Jacopo Busatto et al.

Sea surface temperature (SST) has been thought to be linked with air-sea surface heat fluxes (SHF). General knowledge is that the high frequency variating atmosphere properties modify oceanic quantities due to their slower response. However, recent studies show how in regions where SST gradients and heat losses are stronger – in the Western Boundary Currents region (WBC) – variabilities in SST and SHF are due to internal ocean processes and water dynamic effects. Theoretical models suggest that the correlation between SST and SHF and between SST tendency (namely the time derivative) and THF can be used to retrieve the sources of variations of these two quantities distinguishing to influences due to ocean or atmosphere dynamics (ocean or atmosphere driven regimes). In this study, We use observational data and numerical model outputs with different resolutions to distinguish different regimes of variability and to investigate spatial resolution effects over the Agulhas Current region and the Eastern South Atlantic. In these regions waters flowing southward from the Indian Ocean along the eastern coasts of Africa interact with bathymetry and cold waters of the Antarctic Circumpolar Current (ACC) and the SubTropical Front and generate turbulence and eddies that propagates into the South Atlantic carrying warm and salty waters (Agulhas Leakage). Hence this methodology is particularly effective due to the mesoscale length scale of the physical phenomena that occur here. Observations are retrieved from OAFlux dataset and J-OFURO3. Model data come from the Coupled Model Intercomparison Project (CMIP6). The increase of ocean resolution leads to a better representation of the cross-covariance patterns and cross-correlation forms, indicating an improvement of the eddy-permitting from the eddy-parametrized models’ capability. Covariance maps have been calculated to highlight qualitative patterns for the lead-lag symmetry. We concluded that, while high resolution model data have similar covariance patterns and correlation values to the observations, their low-resolution counterpart, in two cases, fails to reconstruct the signal caused by the ocean dynamics. The stronger impact on the capability of reproduce this interaction phenomenon belongs to the ocean part of the coupled model: the higher, the better is the symmetric properties of the correlation functions (symmetry index) and the greater the transition scale is, implying the needs of a wider filtering window to cancel out the ocean driven regime signal.

How to cite: Busatto, J., Yang, C., Bellucci, A., and Adduce, C.: The  impact of resolution on the air-sea interaction in  the Agulhas current region, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9971, https://doi.org/10.5194/egusphere-egu22-9971, 2022.

17:49–17:56
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EGU22-11638
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ECS
Gesa Eirund et al.

Air-sea interactions substantially modulate oceanic and atmospheric mesoscale variability. Regions of particularly strong oceanic mesoscale activity and hence strong potential for these modulation effects are the highly productive eastern boundary upwelling systems (EBUS), such as the California Current System (CalCS). There, the interactions between atmospheric and oceanic processes can easily alter marine biogeochemical processes or force extreme events with highly anomalous conditions in ocean temperature, pH, and oxygen. Nevertheless, modeling this coupled variability remains challenging due to the small-scale nature of such interactions and the complexity of the system itself. In addition, the extent to which the interplay between atmospheric and oceanic processes impacts the spatial and temporal scales of mesoscale variability and affects the marine ecosystem and ocean biogeochemistry remains largely unknown.

Given these complex interactions between the atmosphere, the ocean, and marine biogeochemistry, we developed a coupled regional high-resolution Earth System Model (ROMSOC). For the atmosphere, ROMSOC uses the GPU-accelerated Consortium for Small-Scale Modeling (COSMO) model, and the Regional Oceanic Modeling System (ROMS) model for the ocean. ROMS in turn includes the Biogeochemical Elemental Cycling (BEC) model that describes the functioning of the lower trophic ecosystem in the ocean and the associated biogeochemical cycles. Our current model setup includes thermodynamical and mechanical coupling between the atmosphere and the ocean. Here, we present results from 10-year long coupled simulations for the CalCS at kilometer-scale resolution. We find that the inclusion of atmospheric feedbacks strongly affects oceanic dynamics such as upwelling strength, the advection of water masses and mixed layer depth. In a next step, we will test the hypothesis if this strong mesoscale coupling of the atmosphere and the ocean impacts the spatial and temporal scales of oceanic mesoscale variability such as marine heatwaves and can potentially act to shorten their duration.

How to cite: Eirund, G., Münnich, M., Leclair, M., and Gruber, N.: Coupled atmosphere-ocean dynamics in the California Current System off the U.S. West Coast, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11638, https://doi.org/10.5194/egusphere-egu22-11638, 2022.

17:56–18:03
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EGU22-12702
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ECS
Anneke ten Doeschate et al.
18:03–18:10
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EGU22-12821
Roberto Sabia et al.

Remote sensing measurements of sea surface salinity (SSS) and sea surface temperature (SST) have been used to generate satellite-derived surface T-S diagrams [1], and to compute surface density flux, spiciness and water masses (WM) formation rates and extension [2].

More recently [3], this framework has been expanded in several directions, ranging from the extension of the studied basins and their temporal span, to the inclusion of a wider pool of source datasets. Satellite uncertainties have also been propagated to the final estimates (including also heat and freshwater fluxes uncertainties) of water masses formation rates and location. Several water masses have been characterized, showing a remarkable consistency with literature estimates.

The current efforts are devoted to additional investigation pathways. Firstly, it has been studied the impact on the actual estimates of water masses formation of satellite inputs at variable spatial (0,5  to 1 ) and temporal (weekly to monthly) scales. Secondly, the temporal evolution of the estimates over a 10-yr-long timespan has been studied, both in the T/S and geographical domains, detecting possible linear trends and anomalies. Lastly, investigation on additional water masses in the Pacific Ocean under the influence of ENSO variability is ongoing.

[1] Sabia R., et al. (2014), A first estimation of SMOS‐based ocean surface T‐S diagrams, J. Geophys. Res. Oceans, 119, 7357–7371.

[2] Sabia R., et al., Variability and Uncertainties in Water Masses Formation Estimation from Space, Ocean Sciences 2016, New Orleans, LA, USA, February 2016.

[3] Piracha A., et al., Satellite-driven estimates of water mass formation and their spatio-temporal evolution, Frontiers in Marine Science, 2019.

How to cite: Sabia, R., Caughtry, J., Fernandez-Prieto, D., and Piracha, A.: Spaceborne Water Mass formation detectability and temporal evolution , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12821, https://doi.org/10.5194/egusphere-egu22-12821, 2022.