资源环境科技发展态势分析平台

Short-duration rainfall extremes are expected to intensify with warming at around 7%/K, following the Clausius–Clapeyron (CC) relation, causing concomitant increases in flash floods. Observed hourly rainfall extremes show consistent CC-scaling with dewpoint temperature across all land regions. Here, we use two global climate reanalysis products (ERA5 and MERRA-2) to examine consistency in scaling with observations, in ungauged regions and over the oceans. We find that reanalyses underestimate observed scaling, but ERA5 provides better estimates than MERRA-2. Scaling rates at high- and mid-latitudes are similar to observations, at CC, while over the tropics mixed negative- and super-CC scaling rates are seen. We show underestimation of scaling rates over the tropics is related to deficiencies in simulations of extreme rainfall over orographically complex and convection dominated regions. Importantly, both reanalyses indicate scaling rates over the ocean are substantially higher than over land, with implications for extreme weather events originating over the ocean.