Performance of RegCM4.5 in Simulating the Regional Climate of Western Tianshan Mountains in Xinjiang, China

Quanying Cheng,Fan Li

doi:10.3390/atmos12121544

Abstract

The western Tianshan Mountains region in China has a complex topography where basins, mountains and glaciers co-exist. It is of great significance to study the sensitivity of meteorological factors in this region to different parameterization schemes of climate models. In this paper, the regional climate model RegCM4.5 is used to simulate the meteorological factor (mean temperature, maximum temperature, minimum temperature, precipitation and wind speed) occurring in the western Tianshan Mountains region from 2012 to 2016, so as to investigate the effects of different cumulus convective schemes (Grell, Tiedtke and Emanuel), including land cumulus convective schemes (LCCs) and ocean convective schemes (OCCs) on annual and seasonal simulations of meteorological factor by using the schemes of RUN1 (Grell for LCC and Tiedtke for OCC), RUN2 (Tiedtke for LCC and Emanuel for OCC), RUN3 (Grell for LCC and Emanuel for OCC) and ENS (the ensemble of RUN1, RUN2 and RUN3). The results show that the simulations of annual and seasonal meteorological factors are not significantly sensitive to the combination of LCCs and OCCs. In the annual simulations, RUN2 scheme has the best simulation performance for the maximum, average and minimum temperatures. However, other schemes of precipitation simulation outperform RUN2 scheme, and there is no difference among the four schemes for wind speed simulation. In the seasonal simulations, RUN2 scheme still performs well in the simulation of the average, maximum and minimum temperatures for four seasons, except for the simulation of the average temperature in spring and summer. For the simulation of the maximum temperature in summer, RUN2 scheme performs the same as ENS. For the simulation of other seasons, different meteorological factors have different performances in four seasons. Overall, the results show that different combinations of cumulus convection schemes can improve the simulation performance of meteorological factors in the western Tianshan Mountains of Xinjiang.

Highlights

Located in the hinterland of Eurasia, Xinjiang is the largest province with the longest border line and the largest number of neighbors in China, and it has become the most convenient access to Central Asia from the Chinese mainland
The objective of this study is to evaluate the performance of three mixed convective parameterization schemes (CPS) and their ensemble averages, namely, Grell over land and Tiedtke over ocean (RUN1), Tiedtke over land and Emanuel over ocean (RUN2), and Grell over land and Emanuel over ocean (RUN3), with the ensemble being the average of RUN1, RUN2 and RUN3
In the simulation of western Tianshan Mountains in Xinjiang, China, the RUN2 scheme is selected for temperature, maximum temperature and minimum temperature, which can make the simulation results better and closer to the observed values

Summary

Introduction

Located in the hinterland of Eurasia, Xinjiang is the largest province with the longest border line and the largest number of neighbors in China, and it has become the most convenient access to Central Asia from the Chinese mainland. It is a very important region in Asia. Xinjiang has a temperate continental climate, characterized by large temperature differences and abundant sunshine, but little precipitation and a dry climate. Xinjiang is generally deep inland and far from the sea, and the climate types are all temperate continental, there are still significant differences in climate between the southern and northern Xinjiang.

Objectives

Methods

Results

Conclusion