Contribution of the Yellow Sea bottom cold water to the abnormal cooling of sea surface temperature in the summer of 2011

摘要

Satellite-based sea surface temperature (SST) measurements revealed an abnormal cooling anomaly over the Yellow Sea (YS) in the summer of 2011. Using in situ hydrographic profiles, meteorological fields, and an ocean circulation model with a passive tracer experiment, we identified the cold SST anomaly and its connection with the YS Bottom Cold Water (YSBCW), which occupies the central part of the YS below the thermocline in the summer. The summer SST anomalies in the YS showed three cold peaks in 1993, 2003, and 2011 over the past 20 years, but the reasons for the cooling events were different, as one was due to weakened surface heating and the other was attributed to mixing with the YSBCW. In 1993 and 2003, relatively weak surface heating made the surface water cooler compared with that during the other years, whereas in 2011, a strong vertical mixing of water was induced by a typhoon that passed through the central YS, causing the surface water to cool by ~8℃ and the bottom water to warm up by ~4℃. A tracer experiment further confirmed that the vertical heat transfers between the warm surface and the cold bottom water masses when the typhoon passed through the YS interior.