Improving the sectional Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) aerosols of the Weather Research and Forecasting-Chemistry (WRF-Chem) model with the revised Gridpoint Statistical Interpolation system and multi-wavelength aerosol optical measurements: the dust aerosol observation campaign at Kashi, near the Taklimakan Desert, northwestern China

Abstract. The Gridpoint Statistical Interpolation data assimilation (DA) system was developed for the four size bin sectional Model Simulating Aerosol Interactions and Chemistry (MOSAIC) aerosol mechanism in Weather Research Forecasting-Chemistry (WRF-Chem) model. forward tangent linear operators optical depth (AOD) analysis were derived from WRF-Chem code. We applied three-dimensional variational DA to assimilate multi-wavelength AOD, ambient scattering coefficient, absorption measured by sun–sky photometer, nephelometer, aethalometer, respectively. These measurements undertaken during a dust observation field campaign at Kashi northwestern China April 2019. results showed that analyses decreased model aerosols' low biases; however, it had some deficiencies. Assimilating surface particle concentration increased coarse particles episodes, but AOD coefficients still lower than those observed. coefficient separately improved two quantities. However, caused an overestimation of concentrations surface. yielded highest positive bias concentration, AOD. biases operator underestimating mass efficiency. As compensation, excessively fit observed values. best overall improvements obtained simultaneous did not substantially change chemical fractions. After DA, clear-sky radiative forcing −10.4 W m−2 top atmosphere, which 55 % higher value before DA.