Elevation-Dependency of Diurnal Variation of Precipitation in Boreal Summer and Its Probable Response to Global Warming

Abstract

As a critical component of global water cycle, diurnal variation of precipitation (DVP) exhibits significant spatial heterogeneity under topographic effect. However, DVP's dependency on elevation and evolution in a warming climate remain unclear. This study investigates the elevation-dependency of the terrestrial DVP in boreal summer and its evolution using 20-year satellite data. Results show that late-afternoon to evening is the major peak period for boreal summer precipitation across all altitudes, while late night is the secondary peak period at 2–4 km above sea level (ASL). Precipitation tends to peak more in the late afternoon above 5 km ASL compared to lower altitudes. With global warming, the late-afternoon peak is weakening while the evening peak is strengthening, particularly above 4 km ASL. Diurnal precipitation may have become more homogeneous with narrowing amplitude, which is more pronounced at lower elevations. These findings highlight DVP is elevation-dependent and is evolving in probable response to global warming.