Impact of October Snow Cover in Central Siberia on the Following Spring Extreme Precipitation Frequency in Southern China

Mengqi Zhang,Jianqi Sun

doi:10.3389/feart.2021.785601

Abstract

Spring extreme precipitation poses great challenges to agricultural production and economic development in southern China. From the perspective of prediction, the relationship between spring extreme precipitation frequency (SEPF) in southern China and preceding autumn snow cover over Eurasia is investigated. The results indicate that the southern China SEPF is significantly correlated with October snow cover in central Siberia. Corresponding to reduced October snow cover, the vertical propagation of planetary waves is suppressed, which leads to a strengthened stratospheric polar vortex from October to following December. The signal of the anomalous stratospheric polar vortex propagates downward to the surface, contributing to a positive North Atlantic Oscillation (NAO)-like pattern in December. The southwesterlies in the northern Eurasia-eastern Arctic associated with the positive NAO induce sea ice loss in the Barents–Kara seas in January–February, which then tends to enhance the vertical propagation of planetary waves by constructively interfering with the climatological wavenumber-1 component. Therefore, the stratosphere polar vortex is significantly weakened in spring, which further contributes to a negative Arctic Oscillation (AO)-like pattern in the troposphere. The negative spring AO is related to an anomalous cyclone in East Asia, which induces upward motion and moisture convergence in southern China, consequently providing favorable dynamic and moisture conditions for extreme precipitation in the region. The snow cover signal in central Siberia in the preceding October provides a potential source for the prediction of spring extreme precipitation variability in southern China with two seasons in advance.

Highlights

Southern China is a major rice-producing region in East Asia and has a dense population and developed industry, making it vulnerable to extreme precipitation events
The results of this study indicate that the southern China spring extreme precipitation frequency (SEPF) is negatively correlated with the central Siberian snow cover in the preceding October
This cross-seasonal relationship provides a possibility for predicting southern China spring extreme precipitation variability with two seasons in advance

Summary

INTRODUCTION

Southern China is a major rice-producing region in East Asia and has a dense population and developed industry, making it vulnerable to extreme precipitation events. Recent studies have begun to focus on the variability and influencing factors of spring precipitation extremes in southern China from a climatic perspective. Eurasian snow cover is an important influencing factor and prediction source for the Northern Hemisphere climate (Saito et al, 2001; Cohen et al, 2007; Cohen and Fletcher, 2007; Cohen and Jones, 2011; Cohen et al, 2014; Orsolini et al, 2016). It is natural to ask whether the preceding Eurasian snow cover influences the southern China spring extreme precipitation frequency (SEPF). From the perspective of prediction, this study investigates the relationship between the southern China SEPF and Eurasian snow cover in the preceding autumn and the related physical processes. The zonal wavenumber-1 disturbance is obtained by zonal Fourier harmonics

RESULTS

CONCLUSION AND DISCUSSION

DATA AVAILABILITY STATEMENT