Tracing Sea Surface Warming and Cooling in the East China Sea during summer

Abstract

The East China Sea (ECS) is a shallow marginal sea in the western Pacific Ocean and has a connection with strong human activity and economy in East Asia. Changes in oceanographic characteristics associated with global warming and, particularly, the Changjiang River Discharge (CRD), China are of great influence. However, such changes are poorly understood due to the sparse spatial and temporal observation data in this area. In order to understand the occurrence of the sea surface warming and cooling in the ECS during the summer season, we used the matrix analysis among sea surface temperature (SST), air temperature (AT) and heat flux. Hydrographic in-situ data (SST and surface salinity) collected from National Institute of Fisheries Science (NIFS) and KIOST. Daily and monthly SST used the MODIS- aqua data, and daily and monthly AT and heat flux used ECMWF (reanalysis data) from 2003 to 2019 (17 years). SST in the ECS showed the lowest (average: 13.72oC) in March and the highest (average: 28.12oC) in August. AT was highly correlated SST and showed a similar seasonal change. In August, SST was higher than AT and continuously higher than AT until winter. To determine the change of the summer SST, we considered the sea surface warming events that SST anomaly is higher than 1oC, and used SST anomaly value in August to classify the positive and negative periods. Sea surface warming occurred in 2004, 2006, 201