A Global-to-Regional Framework for Assessing Precipitation Inhomogeneity and Its Connection to Extreme Events

Climate change has led to significant shifts in precipitation patterns, with spatial inhomogeneity emerging as a key feature, which is directly related to extreme flooding or drought events. A quantitative method estimating how extreme events affect global precipitation inhomogeneity is crucial for monitoring, understanding, and predicting the role of precipitation variability in driving regional or global climate extremes under ongoing climate change.

In this presentation, we introduce a novel but simple framework that is able to (1) quantify the spatial inhomogeneity of global precipitation and its variability, (2) estimate contributions of different precipitation intensities and (3) assess contributions of regional disparities. Based on this framework, we show that the inhomogeneity of global annual precipitation has increased consistently across multiple datasets in the satellite era (1979–2021), attributed to the increasing area of both extremely high precipitation (over 2000mm per year) and low precipitation (under 250mm per year). Based on the Global Precipitation Climatology Project (GPCP) dataset, the increase in inhomogeneity of global precipitation is primarily contributed by the intra-regional inhomogeneity component of Northern Hemispheric tropical ocean (+60.2%) and Southern Hemispheric tropical ocean (+40.3%), and is partly offset by the inter-regional inhomogeneity component of Northern Hemispheric mid-latitude ocean (-4.5%). Further applied to high-resolution datasets, our framework is particularly effective in revealing the impacts of isolated extreme events, which are often obscured by surrounding normal precipitation or dismissed as noise in global average calculations.