AUTHOR=Song Xiangzhou , Xie Xuehan , Qiu Bo , Cao Haijin , Xie Shang-Ping , Chen Zhiqiang , Yu Weidong
TITLE=Air-Sea Latent Heat Flux Anomalies Induced by Oceanic Submesoscale Processes: An Observational Case Study
JOURNAL=Frontiers in Marine Science
VOLUME=9
YEAR=2022
URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.850207
DOI=10.3389/fmars.2022.850207
ISSN=2296-7745
ABSTRACT=
The classical theory predicts that a geostrophically balanced mesoscale eddy can cause a sea surface temperature (SST) anomaly related to Ekman pumping. Previous studies show that an eddy-induced SST anomaly can result in a sea surface latent heat flux (LH) anomaly at a maximum magnitude of ∼O(10) Wm–2, decaying radially outward from the center to the margin. In this study, we investigate the LH anomalies associated with submesoscale processes within a cyclonic eddy for the first time using recent satellite-ship-coordinated air-sea observations in the South China Sea. Unbalanced submesoscale features can be identified as submesoscale SST fronts. Along the ship track, the SST strikingly decreases by 0.5°C within a horizontal distance of ∼1.5 km and increases quickly by 0.9°C with a spatial interval of ∼3.6 km. The along-track SST is decomposed into three parts: large-scale south-north fronts and anomalies induced by mesoscale and submesoscale motions. Our analysis shows that the amplitude of the LH anomaly induced by the mesoscale SST anomaly is 12.3 Wm–2, while it is 14.3 Wm–2 by unbalanced submesoscale motions. The mean (maximum) spatial gradient of the submesoscale LH anomalies is 1.7 (75.7) Wm–2km–1, which is approximately 1.5 times those (1.2 and 59.9 Wm–2km–1) in association with mesoscale eddies. The spectra of LH and SST anomalies show similar peaks at ∼15 km before sloping down with a power law between k–2 and k–3, indicating the underlying relationship between the LH variance and submesoscale processes.