Observation of Asian dust and air-pollution aerosols using a network of ground-based lidars (ADNet): Realtime data processing for validation/assimilation of chemical transport models

Abstract

Network observations of Asian dust and air-pollution aerosols are being conducted with automatic two-wavelength (1064nm, 532nm) polarization (532nm) lidars. Currently, the lidars are operated at 20 locations including cooperative stations. Aiming at real-time validation/assimilation of chemical transport models, an automatic data processing system was developed. A method using the lidar depolarization ratio is employed to estimate the extinction coefficient profiles of Asian dust and spherical aerosols. At the same time, the attenuated backscattering coefficients at 1064nm and 532nm, and the total depolarization ratio at 532nm are derived. A data assimilation system based on 4-dimensional variational (4DVAR) method was developed for the lidar-network Asian dust data. In the assimilation, the dust emission factor was used as the control parameter. The results show the data assimilation is effective not only for improving the model results but also for estimating the emission in the dust source region.