Google Earth Engine–assisted black carbon radiative forcing calculation over a heavy industrial city in China

Abstract

Black carbon (BC) aerosol has a low content in the atmosphere; however, it has a strong radiative forcing effect and a significant impact on human beings and the environment. BC aerosol radiative forcing (ARF) has a major environmental influence. The main method to calculate the ARF is numerical simulation using a radiation transfer model by inputting atmospheric and surface parameters. Currently, most research studies directly apply the albedo products, which are not the real surface albedo (the blue-sky albedo). Alternatively, they use an empirical formula to calculate the sky diffuse light ratio to obtain the real surface albedo. To overcome these shortcomings, this study develops a new scheme to obtain the BC ARF in Xuzhou City from May 2014 to July 2016 by combining the BC mass concentration, albedo measurements from the Google Earth Engine (GEE) platform, aerosol optical depth (AOD), and microphysical parameters retrieved from the Aerosol Robotic Network (AERONET). Although BC AOD accounts for 3.3 to 17.9% of the total AOD, the BC ARF at the surface (SFC) and top of the atmosphere (TOA) is between − 14.06 ± 4.645 W/m2 and − 4.04 ± 0.437 W/m2 and between 2.93 ± 1.034 W/m2 and 0.74 ± 0.093 W/m2, with average values of − 9.67 ± 2.787 W/m2 and 2.02 ± 0.587 W/m2, respectively. Finally, comparing the BC ARF obtained by different albedo methods shows that the BC ARF change at the TOA is marked, and generally, the BC ARF calculated by the empirical formula method is lower than that calculated by using the blue-sky albedo method.