Lidar detection of high concentrations of ozone and aerosol transported from northeastern Asia over Saga, Japan

摘要

To validate products of the Greenhouse gasesObserving SATellite (GOSAT), we observed vertical profiles of aerosols, thincirrus clouds, and tropospheric ozone with a mobile-lidar system thatconsisted of a two-wavelength (532 and 1064 nm) polarization lidar and atropospheric ozone differential absorption lidar (DIAL). We used theselidars to make continuous measurements over Saga (33.24° N,130.29° E) during 20–31 March 2015. High ozone and high aerosolconcentrations were observed almost simultaneously in the altitude range0.5–1.5 km from 03:00 to 20:00 Japan Standard Time (JST) on 22 March 2015. Themaximum ozone volume mixing ratio was ∼ 110 ppbv. The maximaof the aerosol extinction coefficient and optical depth at 532 nm were 1.2 km and 2.1, respectively. Backward trajectory analysis and thesimulations by the Model of Aerosol Species IN the Global AtmospheRe(MASINGAR) mk-2 and the Meteorological Research Institute Chemistry-ClimateModel, version 2 (MRI-CCM2), indicated that mineral dust particles from theGobi Desert and an air mass with high ozone and aerosol (mainly sulfate)concentrations that originated from the North China Plain could have beentransported over the measurement site within about 2 days. These highozone and aerosol concentrations impacted surface air quality substantiallyin the afternoon of 22 March 2015. After some modifications of its physicaland chemical parameters, MRI-CCM2 approximately reproduced the high ozonevolume mixing ratio. MASINGAR mk-2 successfully predicted high aerosolconcentrations, but the predicted peak aerosol optical thickness was aboutone-third of the observed value.