Abstract:

Persistent high temperature and drought occurred in Guanzhong of Shaanxi Province in summer of 2022, causing serious impacts on the growth and development of crops such as maize, apple and kiwifruit. To study the mechanisms of the occurrence of heat and drought, observations from 46 automatic meteorological stations in Guanzhong area, and ERA-5 hourly and monthly mean reanalysis data were used to study the characteristics and causes of atmospheric circulation during the main high temperature periods. The results showed that (1) the main high temperature periods were mid-late June and early-mid August, with moderate to severe drought in most parts of Guanzhong. (2) Both high-temperature periods were characterised by strong sinking currents, but the causes were different. In June, strong sinking movements were maintained by anomalous pre-ridge negative vorticity advective, while in August, the superposition of the subtropical high and South Asian high caused the positive climate state anomalies and strong sinking movements over Shaanxi. (3) The strong northwesterly airflow in June and the abnormally westerly and strong subtropical high in August weakened the southerly airflow and blocked the source of water vapour, both showing positive anomalies of water vapour flux dispersion, which were not conducive to the occurrence of precipitation. (4) High temperatures and drought had an impact on the yield and quality of food and cash crops. It was recommended that effective measures should be taken before high temperatures to lower field temperatures, replenish plant water, enhance plant transpiration and reduce the degree of crop heat stress.

Key words: high temperature, drought, crops, Guanzhong