Abstract
Abstract
The disparity between observed and projected trends in tropical cyclone (TC) inner-core rain rates remains a fundamental challenge in climate science. Over the past two decades, satellite observations show a decline in inner-core rain rates, whereas climate models and the ERA5 reanalysis project increases under warming. Here we investigate the mechanisms governing this discrepancy. We find that under the transient warming of the recent two decades ($\sim$0.4$^{\circ}$C), moisture-driven rain rate increases have not materialized. Instead, the observed decline reflects falling TC intensity and an expanding radius of maximum wind, with atmospheric stability providing a robust suppressing effect. Conversely, the ERA5 increase is driven by rising reanalyzed intensity and a shrinking radius of maximum wind. Prior model-based studies typically simulate larger warming ($>$1$^{\circ}$C), where moisture increases dominate over suppressing effects to produce net rain rate increases. These findings validate current physical frameworks, building essential confidence in TC inner-core rainfall projections.