Recent Global Decrease in Tropical Cyclone Rain Area

There has been substantial research into recent changes in tropical cyclone (TC) rain rate, but a lack of studies on changes in TC rain area. Using 20 years of global satellite rain estimates from the TRMM Multi-Satellite Precipitation Analysis (TMPA), we observe a significant decrease in the fraction of rainy pixels in the outer region (> 150 km radius) of TCs. This decline is more pronounced for TCs with higher intensity. The decreasing trend implies a shrinkage in the TC rain area, which would have partially offset the increase in TC rain volume due to the observed increase in TC rain rate. Idealized numerical model simulations are utilized to evaluate the effects of changing sea surface temperature and atmospheric stability on the fraction of rainy pixels in a TC. The results indicate that increased atmospheric stability decreases the fraction of rainy pixels in the outer region of TCs, while higher sea surface temperatures increase them.