Physics of Oceans and Atmospheres

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Physics of Oceans and Atmospheres Seminar

Tuesday, August 25 at 3:30 p.m. in Burt 193 and on Zoom

Caique Dias Luko (Scripps/UCSD)

Title: Warming over submesoscale salinity fronts boosts sea surface temperature, air-sea heat fluxes and downward heat transport

Abstract: Submesoscale fronts, with typical length scales from 100s m - 10s km, are ubiquitous in the ocean. Submesoscale temperature fronts drive strong upward heat transport at mid-latitudes in wintertime, being comparable in magnitude to net air-sea heat fluxes, and playing  an important role on the global heat budget. Here, we explore how warming over submesoscale salinity fronts can alter sea surface temperature variability and the direction of vertical heat transport, influencing ocean heat uptake and air-sea heat fluxes. We investigate salinity fronts on the Texas-Louisiana shelf during spring/summer, as this region experiences enhanced heating and intense river discharge from the Mississippi-Atchafalaya rivers. We use satellite, shipboard data and numerical simulations to show that salinity fronts exposed to sea surface heating develop warm submesoscale filaments due to the convergence of warm waters at fronts and the Lagrangian history of atmospheric heat fluxes along water parcel trajectories. High SST anomalies observed at these fronts lead to enhanced submesoscale latent heat flux anomalies (50-100 W m^{-2}). In addition, a submesoscale-resolving simulation shows that downward heat transport at these fronts reaches up to 2000 W m^{-2}, leading to a twofold increase in subsurface heat content relative to a submesoscale-permitting simulation. A global analysis of the co-occurrence of salinity fronts and net surface heating identifies where this submesoscale phenomenon is likely to occur. This submesoscale process can only be resolved in high-resolution observations and simulations. Thus, the absence of these fronts in coarse resolution models can contribute to global model biases in SST and ocean heat uptake.


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