Analysis of the Causes of a Persistent Heat Wave in the Summer of 2022 in the Northwest Arid Region

Abstract

Based on station data and high-resolution reanalysis data， this study conducted a diagnostic analysis of the persistent heat wave that occurred in the arid region of northwest China during the summer of 2022 and quantified the contributing factors.The results showed a total of 2092 occurrences of high temperatures， primarily concentrated in the northern part of northwest China.Furthermore， the high temperatures exceeded historical extreme values recorded in the past 40 years at 108 stations and persisted for over 10 days at 98 stations， both of which are historically rare occurrences.The studied heatwave has a wide impact and long duration.During the prolonged period of high temperatures， the South Asian high-pressure center is positioned further north than usual and exhibits stronger intensity.In the early stages of the event， it is influenced by the warm ridge in the mid to upper levels， which gradually shifts eastward during the transition period.The continental high-pressure system gradually extends eastward and connects with the western Pacific subtropical high-pressure system （referred to as the "Western Pacific Subtropical High"） which extends both eastward and westward.This connection affects most of the northwestern regions.Within the northwestern region， there is strong water vapor divergence， making it difficult for precipitation to form.At the same time， there is an abnormal strengthening of the descending airflow， leading to warming in the upper atmosphere， which favors the development and maintenance of hot weather conditions.Whether it is in the early or later stages of the process， the temperature advection term contributes minimally to the warming process， while the vertical transport term and non-adiabatic heating term are key factors that influence extreme heat weather.From the perspective of influencing factors， the early stage of the process is mainly influenced by dynamic factors， while in the later stage， thermodynamic contributions dominate after the formation of a stable heat do stable heat dome.

Keywords

• persistent high temperature
• cause analysis
• abnormal characteristics
• thermal contribution