Reply on AC2

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> The supercyclonic storm Amphan occurred in the central Bay of Bengal (BoB) in May 2020, and a phytoplankton bloom occurred in the upper ocean that was devoid of background nutrients. The dynamic mechanism of the chlorophyll-a (Chl-a) bloom was researched based on satellite remote sensing data, reanalysis data and Argo float data. During the passage of Amphan, an inertial oscillation with a two-day period appeared in the thermocline and lasted for approximately two weeks. After the passage of Amphan, a cyclonic eddy with a maximum vorticity of approximately 0.36 s^&minus;1 formed in the study area (Box A). Additionally, horizontal transport of Chl-a also occurred when the maximum inlet fluxes through the western and northern sides of Box A were 0.304 mg m^&minus;2s^&minus;1 and &minus;0.199 mg m^&minus;2s^&minus;1, respectively. With the weakened thermocline and thinner barrier layer thickness (BLT), nitrate and Chl-a were uplifted to the upper ocean by upwelling. Then, with the high photosynthetically available radiation (PAR) in the upper ocean, a phytoplankton bloom occurred. This study provides new insights into the biological responses in the BoB during the passage of tropical cyclones (TCs).