The research group of Professor Hiroaki Ueda of the University of Tsukuba, Department of Life and Environment, collated the results of numerical experiments using climate models with observational data, and the decrease in precipitation in the East Asian region is due to the influence of seawater temperature in the tropical zone. I made it clear.
Examining precipitation data based on ground and satellite observations, there is a clear regional difference in precipitation in the Asian monsoon region in recent years (more precipitation in the west and less precipitation in eastern Asia). Has been confirmed.In the long term, it is generally thought that the amount of precipitation associated with monsoons will increase due to the progress of global warming, but the cause of regional differences confirmed by the trend over the last decade has not been clarified. ..
In this study, we have succeeded in reproducing the regional differences in precipitation distribution in recent years by performing numerical calculations using an atmospheric general circulation model, assuming the observed sea surface temperature distribution.Furthermore, when the sea surface temperature was set and tested by dividing it into the tropical Pacific Ocean, the tropical Indian Ocean, and the tropical Atlantic Ocean, it was found that the warm seawater in the tropical western Pacific Ocean reduced the precipitation in East Asia.When the sea surface temperature in the tropical western Pacific Ocean is high, convective activity near the Philippines becomes active and a lot of heat of condensation is released into the atmosphere.Due to the action of this heat, atmospheric flow is generated not only in the east and west but also in the north and south directions, and as a result, the atmospheric pressure rises near Japan and the precipitation in East Asia weakens.This study reveals that tropical oceans affect a wider range of climates than previously known.
By clarifying the mechanism of climate change in this way, it is possible to predict with higher accuracy not only seasonal precipitation but also under what conditions abnormal weather such as heavy rain and drought is likely to occur. It is expected that it will be.
