Research progress on the water vapor channel within the Yarlung Zsangbo Grand Canyon, China

Abstract

The Second Tibetan Plateau Scientific Expedition and Research Program tasked a research team with the “Investigation of the water vapor channel of the Yarlung Zsangbo Grand Canyon (INVC)” in the southeastern Tibetan Plateau (TP). This paper summarizes the scientific achievements obtained from the data collected by the INVC observation network and highlights the progress in investigating the development of heavy rainfall events associated with water vapor changes. The rain gauge network of the INVC can represent the impacts of the Yarlung Zsangbo Grand Canyon (YGC) topography on precipitation at the hourly scale. The microphysical characteristics of the precipitation in the YGC are different than those in the lowland area. The GPM-IMERG (Integrated Multi-satellitE Retrievals for Global Precipitation Measurement) satellite precipitation data for the YGC region should be calibrated before they are used. The meridional water vapor flux through the YGC is more important than the zonal flux for the precipitation over the southeastern TP. The decreased precipitation around the YGC region is partly due to the decreased meridional water vapor flux passing through the YGC. High-resolution numerical models can benefit precipitation forecasting in this region by using a combination of specific schemes that capture the valley wind and water vapor flux along the valley floor.

摘要

第二次青藏高原科学考察研究在青藏高原东南部组建了雅鲁藏布大峡谷水汽通道科学考察分队, 本文主要总结了该科考分队近几年开展的观测研究以及利用该分队建立的观测网收集的观测数据所取得的科学成果, 重点介绍了与大峡谷水汽输送相关的强降雨过程的研究进展; 研究主要发现科考分队在大峡谷建立的雨量筒观测网可以代表该地区地形对小时降水量的空间影响; 藏东南降水的微物理特征与低海拔地区有明显差异; GPM卫星降水数据在大峡谷地区存在干偏差的问题, 使用前需进行校准; 穿越大峡谷的经向水汽输送对青藏高原东南部的降水有重要影响, 大峡谷周边区域降水量的减少可能是由于穿越大峡谷经向水汽通量的减少造成; 使用特定云降水方案的高分辨率数值模型可以较好的捕捉大峡谷内的风场和水汽输送时, 该模型能对该地区夜间强降水做出准确预报.