Publications

Xu, XT; Liu, C; Wang, JD; Yin, Y; Zhu, XJ (2022). Long-term multidataset direct aerosol radiative forcing and its efficiencies: Intercomparisons and uncertainties. ATMOSPHERIC RESEARCH, 267, 105964.

Abstract
Direct Aerosol Radiative Forcing (DARF) characterizes aerosol influences on the radiative energy budget due to scattering and absorption of solar radiation, while clear uncertainties remain in both global and regional DARF estimations due to differences in aerosol properties and time periods considered. Through a multidataset strategy, this study systematically investigates the DARFs over Beijing, China, between 2001 and 2020. Ground-based observations from AERONET are used as references , and two satellite-based datasets (MODIS and MISR), atmospheric reanalysis (MERRA-2) and numerical modeling (WRF-CMAQ) are considered. We unify the numerical simulations for DARF to ensure a fair intercomparison among different datasets. Fortunately, the aerosol amount at the AERONET locations in Beijing can well represent those over the entire city region, and the average DARF at the top of the atmosphere (TOA) in the past twenty years is found to be --36W/m(2) in Beijing. The relative differences in DARFs among different sources range between approximately-40% and 10%, and those in DARF efficiencies (DARFEs) are in a similar range (besides AERONET and MISR). The correlation coefficients on DARF between the AERONET and MERRA-2 results are found to be approximately -0.75, and both MODIS and MISR result in correlation coefficients with AERONET over 0.80. However, the agreement at the MISR TOA DARF is caused by smaller AOD and larger DARFE. The DARF uncertainties based on AERONET, MODIS and MISR range from approximately 10% to over 20%. For the numerical simulations, the WRF-CMAQ results agree reasonably with the observation-based results, while their DARF magnitudes are merely about one-third of those from observation-based results. Clear differences among DARFs given by different types of datasets indicate that the uncertainties in direct aerosol forcings cannot be neglected, and that more efforts are still needed to unify and to improve our understanding of them.

DOI:
10.1016/j.atmosres.2021.105964

ISSN:
1873-2895