The spatial distribution of precipitation and topography in the Qilian Shan Mountains, northeastern Tibetan Plateau

Abstract The mutual interrelation of orographic precipitation pattern and topography is key to understanding the competing role of tectonics and climate in landscape evolution. However, the relationship between precipitation and topography across arid to semiarid orogens has received little attention because of limited data availability. As a global successor to Tropical Rainfall Measuring Mission (TRMM), the Global Precipitation Measurement (GPM) extends precipitation measurements to mid- and high latitudes since 2014. In this study, we process one year of GPM precipitation with a spatial resolution of 0.1° × 0.1° across the arid to semiarid Qilian Shan Mountains to examine the spatial correlation between topography and precipitation. Though short, this data set provides reasonable precipitation when compared with other weather station relevant estimates. We then use nine orogen-perpendicular swath profiles to examine the influence of topography on precipitation distribution through the range. The results show that precipitation variation displays a significant elevation control with precipitation peaks in the high elevation mountain interior. We further compare the GPM precipitation with elevation and local relief within each swath extent. The results show that precipitation uniformly increases with increasing elevation for nine swaths, which is consistent with the elevation-controlled precipitation pattern. We find precipitation and local relief are positively correlated for five swaths but not for the remaining four swaths. Based on published data for uplift and erosion, we suggest that the presence or absence of such a correlation indicates whether mountains are in topographic steady state or in a transient state of relief production.