Abstract:

Based on daily air quality data, conventional meteorological observations, and ERA-Interim reanalysis data from 2015 to 2018, the characteristics of the ozone pollution process and its meteorological conditions in the eastern Qinghai urban agglomeration were analyzed.The results show that the maximum and minimum temperature, temperature dew point difference, sunshine duration, and total radiation are the positive influencing factors of ozone pollution in the eastern Qinghai urban agglomeration, among which the maximum temperature, temperature dew point difference, and total radiation influence the most significantly.Sea level pressure, 24-hour pressure, and temperature variation, total and low cloud cover are the negative impact factors, among which the sea level pressure and 24-hour temperature influence the most significantly.The surface weather system types on ozone pollution days mainly include low-pressure type, low-pressure front type, and pressure equalizing field type, among which the low-pressure front type and low-pressure type are the most conducive to the occurrence of ozone pollution process, which appear stable and not prone to be destroyed.On ozone pollution days, the surface layer is controlled by hot low pressure background, whereas the weak convection in the middle layer is inhibited by the stable air flow above, which is affected by the divergence circulation and subsidence movement (low-pressure type) due to the high-pressure center or ridge, rarely appearing vertical movement (low-pressure front type and even pressure type).Multiple inversion layers in the vertical direction, a significant dry zone in the ground layer, and lower wind speed on the whole provide favorable atmospheric stratification conditions for ozone pollution over the eastern Qinghai urban agglomeration.

Key words: Ozone pollution days, Weather type, Atmospheric stratification