In this study, analysis of observations and numerical simulations over the past 39 years have revealed that rain clouds in the Sahel region trigger high pressures over Japan, resulting in an increase in Japan's temperature.
The Sahel region, which stretches in a belt shape to the south of the Sahara Desert, is the land area with the most active rain clouds next to the Amazon, and it rains a lot during the rainy season (June to September).Rain clouds that cover the Sahel region intensify the high pressure over northern Africa and meander the westerlies that blow over Europe.The meandering continues to East Asia and Japan, which are located downstream of the westerlies. Therefore, Japan tends to get hot.

　From this mechanism, it is thought that the more rain clouds develop in the Sahel region, the more high pressure overhangs in Japan, causing intense heat.In fact, in 2018, when Japan recorded the highest heat wave in the history of observation, record rainfall was also observed in the Sahel region.

　Furthermore, it is said that rainfall in the Sahel region has begun to increase in recent years, and if this trend continues, it is highly likely that the heat wave will continue to occur frequently in Japan.The perspective of the effects of rain clouds on distant tropical lands such as the Sahel region has been overlooked with regard to extreme weather in Japan, but this research will open up new developments in the elucidation and prediction of extreme weather in Japan and Asia. Be expected.

Paper information:[Climate Dynamics] Possible semi-circumglobal teleconnection across Eurasia driven by deep convection over the Sahel