The signature of air-sea sensible heat fluxes associated with mesoscale eddies in the South China Sea

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.