Hongjian Tan1,2 | Rongshuo Cai 1
1Third Institute of Oceanography, State Oceanic Administration, Xiamen, China
2State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics,
Chinese Academy of Sciences, Beijing, China
The East China Seas (ECS) encountered its warmest monthly mean sea surface temperature (SST) in August 2016, based on the high-resolution satellite SST product (1982–2016). The area-averaged monthly SST over the ECS (28°–39°N, 120°– 130°E) reached up to 28.3 °C, 2 °C above normal that exceeds two times of SD. The isotherms of 28.5 and 30 °C extended to 36° and 32°N, respectively, both reaching their unprecedented northernmost locations. The heat budget analysis indicated that this extreme warming event in the ECS was predominantly attributable to the combined effects of oceanic advection (0.18 °C, ~24%) and net heat flux (0.44 °C, ~58%), with the latter being the dominant contributor. Further, the extreme ECS warming is induced by the strong adiabatic descent motion with increased downward solar radiation due to the anomalous anticyclonic circulation over the north western Pacific, which is closely linked to the negative phase of the Indian Ocean Dipole (IOD) with robust heating over the tropical eastern Indian Ocean and western Pacific. Additionally, the anticyclonic circulation anomalies promoted the intrusion of warm water of the Kuroshio across the ECS shelf, which also contributed to the forming of enhanced ECS warming. It is further found that most of the ECS warming events can be explained by the precursor signals of negative IOD with 1–3 months ahead, which have important implications for prediction.
East China Sea, extreme SST, the Indian Ocean dipole