Un-uniform Sea Surface Temperature Warming And Its Association With Precipitation Change Over Tropical Oceans Based On CMIP5Data

Using the global monthly mean data from CMIP5, monthly precipitation data provided by CMAP and monthly sea surface temperature data from HadlSST, the un-uniform sea surface temperature (SST) warming and its association with precipitation change over tropical oceans are analyzed based on the various meteorological statistical methods. The main results are as follows:(1)The characteristics of non-uniform sea surface temperature warming and their causes over tropical Pacific, Indian and Atlantic Ocean are analyzed. The results of9oceanic models ensemble mean show that annual spatial distributions of the variations in SST exhibit non-uniform patterns over the three tropical oceans under global warming. However, their causes responsible for these non-uniform patterns are quite different. The oceanic dynamic processes play a leading role in the equator and over the area north of equator in the tropical Pacific Ocean, while the atmospheric thermal effect becomes more important over the area of the south of equator. In addition, the oceanic upwelling/downwelling acts a different role in the eastern and western tropical Pacific Oceans. For the most area of the tropical Indian Ocean, the variations in sea surface temperature is not well explained by the air-sea heat flux exchange and the effect of upwelling/downwelling on the SST variability is consistent with that of the temperature advection. For the tropical Atlantic Ocean, the SST variability in the areas near the equator is the result of the temperature advection in combination with upwelling/downwelling. The temperature advection and upwelling/downwelling play a leading role in the variation of SST over the northern and southern of the tropical Atlantic Ocean, respectively.(2)The relationship between variations of sea surface temperature and precipitation and its causes over tropical Pacific and Indian Ocean are analyzed. The results of20atmospheric models ensemble mean show that annual spatial distributions of the variations in SST and precipitation over tropical Pacific Ocean are associated with the "warmer-get-wetter" mechanism under global warming. However, differences between seasonal and annual mean patterns are obvious. Both zonal and meridional positional deviation between the local maximum SST and precipitation is detected in winter and spring, but only opposite meridional deviation in summer and autumn. In addition, there are some differences between the eastern and western tropical Pacific Ocean. Annual spatial distributions of the variations in SST and precipitation over tropical Pacific Ocean show the symmetrical distribution and are related to the so-called "warmer-get-wetter" mechanism. Meanwhile, similar positional deviation exists over the tropical Indian Ocean in winter and spring as well. Moreover, seasonal changes in precipitation over two oceans are both associated with the "warmer-get-wetter" and the "wet-get-wetter" mechanisms.