Comment on hess-2022-103

Abstract

Altitudinal precipitation gradient plays an important role in the interpolation of precipitation in the Third Pole (TP) region, where the topography is very complex but in-situ data are very sparse. This study proves that the altitude dependence of precipitation in the TP can be reasonably reproduced by high-resolution atmospheric simulations. Results show that most of the sub-basins have positive relative precipitation gradients (RPGs, precipitation changes per 100 m elevation difference relative to basin-average precipitation) among the 388 sub-basins of the TP. The RPGs derived from annual mean precipitation range from about -5.00 % in the Himalaya region to more than 20.00 % in the Qaidam Basin. Generally, the RPGs are large in the center of TP, but small in the east and west, meanwhile, they are large in winter and spring but small in summer and autumn. Such a spatiotemporal pattern is related to the local weather conditions. Further analyses demonstrate that the RPGs have strong negative correlations with relative humidity but strong positive correlations with wind speed, which is because dry air tends to reach saturation at high altitudes, while stronger wind can bring more humid air to high altitudes. These findings provide useful information for the interpolation of precipitation within and beyond the TP, and are expected to provide some references to further hydrometeorological applications.