Euphotic Zone Depth Anomaly in Global Mesoscale Eddies by Multi-mission
Fusion Data
Abstract
As the waters of marine primary production, the euphotic zone is the
primary living environment for aquatic organisms. Eddies account for
90% of the ocean’s kinetic energy and affect marine organisms’ habitats
by the excitation of vertical velocities and the horizontal advection of
nutrients and ecosystems. Satellite observations indicate that
anticyclones mainly deepen the euphotic zone depth, while cyclones do
the opposite. Eddy-induced euphotic zone depth is inversely correlated
with the eddy-induced chlorophyll concentration. The anomalies reach 5m
on average in the region of high eddy amplitude and frequent eddy
occurrence. In addition, we found that the anomalies have an extreme
value in each of the 5°-23° and 23°-55° and reach a maximum at around 40
degrees with the increase of latitude. Secondly, the anomalies are
characterized by large near-summer and small near-winter. In the
eddy-center coordinate system, the minus gradient direction of the
negative anomaly is consistent with the background flow field and the
direction of eddy movement. Meanwhile, the anomaly increases along the
radial direction to about 0.2r and then decreases. Finally, there is a
significant linear correlation between the anomaly magnitude and eddy
amplitude. The conclusion of this research and related mechanism
explanation contributes to marine biology research and conservation,
estimates of marine primary productivity, and understanding of the
biogeochemical properties of eddy modulation in the upper water column.