Maximum precipitation altitude on the northern flank of the Qilian Mountains, northwest China

Abstract

Abstract Investigation of the altitude of maximum precipitation (AMP) and the factors that determine this height supports the understanding of vertical precipitation distribution in mountains. Based on the field precipitation measurement on the northern flank of the Qilian Mountains, the AMP was investigated at vertical profiles from 1,483 to 4,484 m. It found a 2,300 m-AMP in winter and a 4,200 m-AMP in other seasons and on a yearly scale. The AMPs increase from the cold and dry season to the warm and wet season and therefore increase with precipitation. During winter, the interaction of the predominant high-pressure system, the thermal inversion layer below 2,200 m, and the westerly lead to the 2,300-m AMP. In other seasons, the convergent Tibetan Plateau monsoon causes the water vapor move to the Qilian Mountains, and the enhanced uplifting by the mountain produces greater precipitation with altitude, forming the AMP at the higher areas. The front steepest terrain is the primary factor causing the formation of 4,200-m AMP in the study area. The annual AMP may be roughly equal to seven-eighths of the altitude of the mountain top on the north flank of the Qilian Mountains.