Simulations of Aerosol Optical Properties to Top of Atmospheric Reflected Sunlight in the Near Infrared CO2 Weak Absorption Band

Abstract

Over the Asian continent, high aerosol loading is critical to ensure the high accuracy of CO2 retrieval in the near infrared absorption band. Simulations were per-formed to explore the effect of light path modification by aerosol son the atmospheric CO2 near infrared band (6140–6270 cmñ1). The Vector LInearized Discrete Ordinate Radiative Transfer (VLIDORT) model and the Line-By-Line Radiative Transfer Model (LBLRTM) were used for forward calculations. The U.S. standard atmosphere was used for atmospheric profiles. The results indicate that the aerosols caused similar effects to increases in CO2 in the planetary boundary layer and became more significant with aerosol layer rising while aerosol optical depth was 0.1. This effect will cause an over estimation of the CO2 mixing ratio in the retrieval process and an under estimation in the aerosol layer. The results also indicate that the effect of urban and industrial aerosols is smaller than that of non-absorbing and dust aerosols because of the nearly constant absorption properties in the near infrared band.