A novel simplified method for surface albedo together with a look-up table to get an 18-year assessment of surface aerosol direct radiative effect in Central and East China

Abstract

Calculating the aerosol direct radiative effect (ADRE) is significance for estimating the influence of aerosols. However, calculating ADRE through the radiative transfer model at large scales and for long periods is time-consuming. In this paper, a linear relationship between surface albedo and surface shortwave ADRE (ADRESW) was proposed together with a look-up table to simplify the calculation. The linear relationship is tested and remains reliable as atmospheric properties vary. Validation that compared the results calculated with and without simplifications shows high coefficient of determination (0.97). The time required for calculation with the simplification is only 1/2630th of the unsimplified calculation, which reveals that our method greatly simplified the calculation and maintains high accuracy. Based on the simplification, daily surface ADRESW under clear-sky conditions over Central and East China from 2001 to 2018 is calculated and analyzed. Central and East China has a regional average aerosol optical depth (AOD) of 0.66 and surface ADREsw of −34.33 W/m2. The North China Plain (0.83, −41.42 W/m2), The Jianghan Plain (0.79, −40.33 W/m2) and the Yangtze River Delta City Agglomeration (0.90, −46.50 W/m2) feature heavy aerosol loading and a strong cooling effect. The inter-annual AOD and cooling effect decreased by 37.60% and 33.21%, respectively, after the 2011 accord to decrease anthropogenic emissions, proving the success of efforts by the Chinese government to protect environment. A study of daily shortwave aerosol radiative effect efficiency found that sunshine duration is the primary controlling factor.