Characteristics of the Vertical Gradient of Rainfall in the Yarlung Tsangbo Grand Canyon, China

The Yarlung Tsangbo Grand Canyon, situated in the eastern section of the Himalayas, serves as the most important channel for transporting South Asian monsoon water vapor to the Tibetan Plateau. However, owing to the lack of observational data, the rainfall characteristics in this region remain unclear. In this study, a vertical observation network, characterized by intervals of approximately ۳۰۰ meters between ۸۰۰ and ۴۲۰۰ meters, was established within the canyon. Based on the analysis of in situ data from ۲۰۲۰ to ۲۰۲۲, the results demonstrate that: (۱) A rainfall peak manifests at approximately ۲,۴۰۰ meters above mean sea level, with an average rainfall amount exceeding ۲,۸۰۰ mm during the South Asian summer monsoon season (May to October); (۲) Heavy rainfall accounts for the largest contribution in excess of ۳۰% to the total precipitation; (۳) The diurnal cycle of rainfall exhibits a single nocturnal peak with the amplitude increases and then decreases with increasing altitude. The spatiotemporal characteristics of rainfall indicate the unique climate within the canyon. Furthermore, the insights derived from this study provide the crucial observational support to improve satellite inversion inaccuracies and simulation biases inherent in weather and climate models specific to the Yarlung Tsangbo Grand Canyon.