A case study of weather impact on air pollution during the COVID-19 pandemic in South Africa

This study investigates climate, weather characteristics, and air pollution during the third COVID19 wave in South Africa. During this time, a decrease in of SO2 and NO2 column mass was observed. The investigation displays a positive trend in for tropospheric Ozone (O3) mass mixing in winter over the last two decades with a fitted slope of 1.0005. Despite the negative trend for the daily changes (for all 12 months) of the total column mass density for PM2.5 during the year before the pandemic and two years after for pandemic years, they have slightly increased specifically during winter COVID-19 third wave time. The temporal seasonal yearly time changes (1961-2021) of different meteorological parameters such as surface temperature, low-level vertical pressure velocity, low-level relative humidity, and precipitation rate over South Africa show sharp changes from 2020 to 2021. This analysis indicates rather colder surface temperatures, smaller but positive low-level vertical velocity, slightly higher low-level relative humidity, and higher total country precipitation rate in the study area during the COVID-19 pandemic years. Weather chart analysis displays a very stable atmospheric condition during the third wave of COVID-19 peak time. This is correlated with the extension of the atmospheric ridge associated with a blocking high pressure, downward motion, positive vorticity, and rather weak winds specific in the north, west, and central areas causing atmospheric stability and possible accumulation of the atmospheric pollution corresponding to the higher COVID-19 cases during the South Africa third wave.