Land-surface processes and summer-cloud-precipitation characteristics in the Tibetan Plateau and their effects on downstream weather: a review and perspective

Abstract

Correct understanding of the land-surface processes and cloud-precipitation processes in the Tibetan Plateau (TP) is an important prerequisite for the study and forecast of the downstream activities of weather systems and one of the key points for understanding the global atmospheric movement. In order to show the achievements that have been made, this paper reviews the progress on the observations for the atmospheric boundary layer, land-surface heat fluxes, cloud-precipitation distributions and vertical structures by using ground- and space-based multiplatform, multisensor instruments and the effect of the cloud system in the TP on the downstream weather. The results show that the form drag related to the topography, land–atmosphere momentum and scalar fluxes is an important part of the parameterization process. The sensible heat flux decreased especially in the central and northern TP caused by the decrease in wind speeds and the differences in the ground-air temperatures. Observations show that the cloud and precipitation over the TP have a strong diurnal variation. Studies also show the compressed-air column in the troposphere by the higher-altitude terrain of the TP makes particles inside clouds vary at a shorter distance in the vertical direction than those in the non-plateau area so that precipitation intensity over the TP is usually small with short duration, and the vertical structure of the convective precipitation over the TP is obviously different from that in other regions. In addition, the influence of the TP on severe weather downstream is preliminarily understood from the mechanism. It is necessary to use model simulations and observation techniques to reveal the difference between cloud precipitation in the TP and non-plateau areas in order to understand the cloud microphysical parameters over the TP and the processes of the land boundary layer affecting cloud, precipitation and weather in the downstream regions.

Parameterizations of Entrainment‐Mixing Mechanisms and Their Effects on Cloud Droplet Spectral Width Based on Numerical Simulations

“…As "the world water tower," the Tibetan Plateau (TP) tremendously affects water budget in this region, as well as the radiation balance, weather and climate of East Asia (Chen et al, 2020;Fu et al, 2020;Wu et al, 2015;Xu et al, 2008Xu et al, , 2014, and global stratosphere (Bian et al, 2020). In the boreal summer, convection is easy to be triggered, and clouds prevail over TP (Chen et al, 2019;Li et al, 2020;Li & Zhang, 2016;Liu et al, 2015;Wang et al, 2014;Yu et al, 2004).…”

Diagnostic analysis of a regional heavy snowfall event over the Tibetan Plateau using NCEP reanalysis data and WRF

“…As suggested by Fu et al (2020), the weather systems such as the shear line and low vortex, moisture as well as atmospheric stability especially before and after a precipitation should be focused in the future researches. Such the work could be seen from our current study.…”

“…In order to explore the initialization and evolution mechanisms of local heavy snowfall over the Tibetan Plateau, a lot of research has been focused on water vapor and the thermodynamic and dynamic conditions (Zhang et al 2004;Dong et al 2018); cold and warm airflow convergence, low-level strong cyclonic vorticity, high-level divergence concurrent with low-level convergence, water vapor transportation and upward motion each play significant roles (Zou and Cao 1991;Shaman and Tziperman 2005;Dong et al 2018;Wang et al 2018). Additional to these atmospheric considerations, local topography strongly influences topographic snowfall (Zou and Cao 1991), and further study has been suggested on the energy and water vapor exchanges caused by complex terrain uplift (Fu et al 2020). These dynamic and thermodynamic factors need to be considered in concert to diagnose and analyze the evolution of heavy snowfall events; this understanding is foundational to the prediction and early warning of any local heavy snowfall event over the Tibetan Plateau.…”

Impacts of TIPEX‐III Rawinsondes on the Dynamics and Thermodynamics Over the Eastern Tibetan Plateau in the Boreal Summer

“…The accuracy of the reanalysis data needs to be improved (Chen et al, 2015; You et al, 2015). More observations should be adopted to the models for more accurate simulations (Fu et al, 2020).…”