Abstract:

The study aims to explore the causes and mechanisms of the occurrence of rare persistent strong convective weather in Guanzhong region and objectively analyze the impact of this process on agriculture. In this paper, the weather situation, water vapor flux dispersion, pseudo-equivalent temperature and environmental parameters of a rare persistent strong weather in July 2021, as well as the meteorological drought index affecting agricultural production and the impact depth of wind and hail on economic forestry and fruits were quantified and objectively analyzed using the new generation of Chinese global atmospheric/land surface reanalysis products, data of conventional high-altitude and ground-based observations, and artificial observation of hail. The results showed that the persistent strong convective weather in Guanzhong region was influenced by the atmospheric long-wave adjustment, with the high altitude cold advection forcing class configuration in the early stage and the low-level warm advection forcing class in the later stage; the transport of low-level easterly airflow, southwest warm and humid airflow at the periphery of the substratum, obvious water vapor convergence and the expansion of the pseudo-equivalent potential temperature dense area and the increase of intensity caused obvious potential instability to provide good water vapor and thermal conditions for the occurrence of strong convective weather at this time. Larger convective effective potential energy, unstable stratification, increased vertical wind shear and appropriate special layer height were favorable potential for the occurrence of strong convective weather. The occurrence of strong convective weather made a positive contribution to drought relief and effective improvement of soil moisture, but local heavy precipitation and windy hail weather caused lodging of some crops and waterlogging or excessive soil wetness in farmland in Guanzhong, which was not conducive to root respiration and nutrient transport of shallow-rooted crops such as corn and kiwi, affecting normal plant growth. A variety of economic forest fruits in the Guanzhong area showed an impact depth of 0.07-0.32 cm and were damaged by shedding. The research results provided the reliable basis for further strengthening agricultural meteorological services and disaster prevention and reduction.

Key words: persistent strong convection, water vapor, thermal, sounding, agricultural impact