Fig. 2: Evolution of relative humidity (RH) and tropospheric ozone column in Beijing.
From: Stratospheric influences on surface ozone increase during the COVID-19 lockdown over northern China
a RH profiles (unit: %) in Beijing averaged over 10–14 February (blue solid line), 15–17 February (red solid line), 18–20 February (green solid line) and 1–29 February (gray solid line, monthly mean values). The scattered cross, circle and triangle symbols represent the RH observations in each selected altitude using the same colors of the corresponding periods. b Tropospheric ozone column in Dobson unit (red bar, unit: DU) based on MERRA-2 data and tropopause height (blue line, unit: km) in Beijing based on radiosonde observations. The horizontal gray solid line indicates the monthly mean value of the tropospheric ozone column in Beijing.
