Air–Sea Interaction in Association with Monthly Anomaly Departure over the Western North Pacific and Tropical Indian Ocean during the Spring-to-Summer Transition

Abstract

Abstract The study analyzes precipitation variability and related air–sea interaction processes over the South China Sea (SCS) and tropical Indian Ocean (TIO) during the spring-to-summer transition season. It is found that physical processes are very different for the variations of seasonal mean and the monthly departures from the seasonal mean. Corresponding to the seasonal mean anomaly, remote forcing from the equatorial Pacific is a major factor for the precipitation variability with a prominent negative feedback of the atmosphere on the ocean. However, from the viewpoint of the monthly anomaly departure from the seasonal mean, a pronounced local coupled air–sea interaction is detected in both the SCS and TIO that features a sequential process of less rainfall, higher sea surface temperature (SST), more rainfall, and lower SST. The evolution of the SST tendency is well coordinated with that of net surface heat flux in the SCS and TIO. During the transition season, shortwave radiation is a dominant term for the SST change in the SCS, whereas both shortwave radiation and latent heat flux are responsible for the SST change in the TIO. The local air–sea relationship shows an obvious spatiotemporal variation during the transition season. Furthermore, the SST anomaly departure in the TIO (SCS) in April (May) could be considered as an indicator for local precipitation anomaly departure in May (June).