Phytoplankton bloom and sea surface cooling induced by Category 5 Typhoon Megi in the South China Sea: direct multi-satellite observations

This study investigated upper ocean responses to Category 5 Typhoon Megi, the most intense typhoon in 2010, using MODIS ocean color data, GHRSST L4 data, sea level anomaly data and sea surface wind data. Remarkable sea surface cooling(similar to 6-7 degrees) with large area was observed mainly to the right side of typhoon track on 22 October, which was mainly attributed to the vertical mixing and upwelling induced by typhoon Megi. However, the sea ace temperature along the typhoon track increased after the landfall of typhoon and then decreased again. Two cold water patches were observed on 29 October, which were well coincident with two cores with maximum SLA decline. Therefore, we attributed the second cooling along the typhoon track to cyclonic eddies which were triggered by typhoon Megi. On the other hand, Strong upwelling was induced by typhoon Megi, which provided perfect conditions for the growth of phytoplankton and caused a significant phytoplankton bloom in the SCS. Relative to historical levels over the same period, the maximum chlorophyll a concentration increased about 20- 30 times.