Research on the Characteristics and Influence Factors of Autumn Continuous Rain in Qinghai Province

Hanwei Yang,Xiaojuan Wang,Guolin Feng,Yawei Yang,Yue Ma,Hongyan Shen

doi:10.3389/feart.2022.801075

Abstract

Using daily precipitation data of national meteorological stations in Qinghai Province and reanalysis data, the main patterns of autumn continuous rain (ACR) are extracted, and key SST areas and circulation factors are searched for to analyze the possible effects on the seasonal and sub-seasonal predictability of ACR in Qinghai Province. The factors with strong precursors mainly include sea surface temperature (SST), Arctic vortex, and subtropical high. The influence of oceanic factors on ACR is relatively independent, while there is an interaction between atmospheric circulation factors. The precursors in spring are from the equatorial east-central Pacific for the main pattern with consistent precipitation distribution, and the Indian Ocean for the pattern with “saddle type” distribution. SST anomalies from the Pacific and Indian Oceans force different circulation patterns that can enhance meridional circulation over Europe-Asia and lead to different precipitation pattern of ACR. The signals from the Arctic vortex and subtropical high in June to July are indicative for ACR. The southward, westward and strong Arctic vortex, together with the south-westward extension of subtropical high over the Atlantic and Pacific can promote more ACR in Qinghai Province. Under the SST forcing and configuration of high and low latitude circulation, the meridional circulation continues to be weak, and the latitudinal circulation to be enhanced over the Eurasia in the early period, and the circulation pattern changes from type-W to type-C, which lead to positive anomaly of ACR in Qinghai Province.

Highlights

Autumn continuous rainfall in Qinghai province has the characteristics of high frequency and long persistency, which is one of the dominant meteorological disasters in Qinghai Province (Shi, 2003)
The negative anomaly of sea surface temperature (SST) is strong enough to extend to Equatorial Western Pacific, and causing a weak and easterly western Pacific subtropical high (WPSH) by weakening the Hadley circulation
Circulation pattern over Atlantic-Eurasian forcing by SST anomaly in Pacific Ocean and Indian Ocean (Calvo et al, 2009; Gu et al, 2017) with teleconnection wave train will lead to anomaly of clod/warm advection and the structure of atmospheric baroclinicity (Lin and Zhang, 2003)

Summary

INTRODUCTION

Autumn continuous rainfall (lasting for days or even more than 10 days, ACR) in Qinghai province has the characteristics of high frequency and long persistency, which is one of the dominant meteorological disasters in Qinghai Province (Shi, 2003). The negative anomaly of SST is strong enough to extend to Equatorial Western Pacific, and causing a weak and easterly western Pacific subtropical high (WPSH) by weakening the Hadley circulation It forms a warm advection over the main rainfall region of the ACR in Qinghai Province (Figure 6A), and brings water vapor from Indian Ocean (Figure 6C) to leading the precipitation pattern of EOF1. The key area, which can affect the consistent pattern of ACR by causing the change of the trough and ridge over Qinghai Province, is located in the middle and high latitudes of the upper Eurasian continent showing a significant positive correlation (Figure 7A). Circulation pattern over Atlantic-Eurasian forcing by SST anomaly in Pacific Ocean and Indian Ocean (Calvo et al, 2009; Gu et al, 2017) with teleconnection wave train will lead to anomaly of clod/warm advection and the structure of atmospheric baroclinicity (Lin and Zhang, 2003)

CONCLUSION AND DISCUSSION

Findings

DATA AVAILABILITY STATEMENT