Source: China University of Science and Technology News

Recently, a research team led by Professor Zhao Chun of the School of Earth and Space Sciences at the University of Science and Technology of China (USTC) has for the first time used a spatial resolution model of global variability to carry out a numerical simulation experiment on the Qinghai-Tibet Plateau at the kilometer scale (4 km) to study the influence mechanism of the plateau's complex terrain on water vapor transport and precipitation in summer. The results show that the global change spatial resolution region encryption simulation can reproduce the circulation and meteorological features of the plateau region well, and quantitatively assess the influence of the complex terrain on water vapor transport and precipitation, and explain the relevant mechanisms. Related work is entitled "Impacts of Topographic Complexity on Modeling Moisture Transport and Precipitation over the Tibetan Plateau in. The title of "Summer" was published in the internationally influential journal Advances in Atmospheric Sciences (selected in the China Science and Technology Journal Excellence Action Plan).

The Qinghai-Tibet Plateau covers a vast area and is the highest plateau in the world. It is also the cradle of the Yangtze River, Yellow River, Indus River and other rivers. As the "water tower of Asia" that feeds Asian civilization, the precipitation in this region has an important impact on the water cycle and ecological environment. Every summer, the prevailing southeasterly winds transport warm moisture from the Indian Ocean to the Qinghai-Tibet Plateau, bringing large amounts of precipitation. The plateau region, especially the Himalayan mountains, has steep terrain, ravines and ravines, and the terrain is extremely complex, which interacts with multi-scale atmospheric processes to form a unique water vapor transport and precipitation process mechanism. In order to more accurately simulate the summer water cycle process of the Tibetan Plateau and deeply understand its change characteristics, it is usually necessary to analyze the complex terrain features at the spatial resolution of kilometer scale or even higher, and simulate and recognize the mechanism of complex terrain on the summer water cycle of the plateau.

FIG. 1 Grid diagram of global change spatial resolution model and schematic diagram of some complex terrain of Himalayas (resolution ~1km°)

Previous research on high resolution simulation mostly uses the regional model to simulate grid nesting encryption, which is limited by the side boundary conditions. The spatial resolution simulation of global variability can better simulate the feedback effect of small-scale processes or forcing on large-scale circulation. In this study, a comparative simulation experiment was carried out between complex and smooth terrain, and it was found that the complex terrain of the plateau increased the regional net water vapor input by ~11%, which had an important effect on the spatial distribution of precipitation in the Himalayan Mountains, but had little effect on the total precipitation in the Tibetan Plateau. Steep terrain leads to a more northerly position of the uplifting air, and the valleys resolved by high spatial resolution can serve as water vapor transport channels. Therefore, it is analyzed that the influence of complex terrain will lead to the overall northward shift of the simulated precipitation over the Himalayan Mountains. These results indicate the necessity of high spatial resolution simulation for the study of the effects of complex terrain on the plateau.

FIG. 2 Schematic diagram of the influence mechanism of the complex topography of the Himalayas on precipitation and water vapor transport

This study shows the application prospect of global change spatial resolution model in the study of weather, climate and ecological environment in the Qinghai-Tibet Plateau region. In the future, Professor Zhao Chun's research group plans to use the spatial resolution model of global change to explore the water cycle, energy cycle, atmospheric environment characteristics and change mechanisms of the Tibetan Plateau, including further exploring the climate effect of the complex terrain of the Tibetan Plateau and the influence mechanism on air pollution transport.

Professor Chun Zhao is the corresponding author of this paper, and Master student Gu Dongze Li is the first author. The research was co-funded by the National Natural Science Foundation of China, the "Double Major Engineering" Research Fund of the University of Science and Technology of China, and the Strategic Key Research Program of the Chinese Academy of Sciences. At the same time, the Supercomputing Center of the University of Science and Technology of China and the Tianhe-2 National Supercomputing Center in Guangzhou provided high-performance computing support for this research.

reference

Li, G. D. Z., H. M. Chen, M. Y. Xu, C. Zhao, L. Zhong, R. Li, Y. F. Fu, and Y. H. Gao, 2022:  Impacts of topographical complexity on modeling moisture transport and precipitation over the Tibet Plateau in summer.  Adv. Atmos. Sci., https://doi.org/10.1007/s00376-022-1409-7

Original link

https://link.springer.com/article/10.1007/s00376-022-1409-7

(School of Earth and Space Sciences, Department of Scientific Research)