Modeling Dust in East Asia by CESM and Sources of Biases

Abstract

East Asian dust has a significant impact on regional and global climate. In this study, we evaluate the spatial distributions and temporal variations of dust extinction profiles and dust optical depth (DOD) over East Asia simulated from the Community Earth System Model (CESM) with satellite retrievals from Luo, Wang, Ferrare, et al. (2015, https://doi.org/10.1029/2002JD002775), Luo, Wang, Zhang, et al. (2015, https://doi.org/10.1002/2014GL062111) (L15), Yu et al. (2015, https://doi.org/10.1016/j.rse.2014.12.010) (Y15), and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) level 3 products. Both L15 and Y15 are based on CALIPSO products but use different algorithms to separate dust from nondust aerosols. We find high model biases of dust extinction in the upper troposphere over the Taklamakan desert, Gobi desert, and Tibetan Plateau, especially in the summer (June-July-August). CESM with dust emission scheme of Kok, Mahowald, et al. (2014, https://doi.org/10.5194/acp-14-13023-2014) and Kok, Albani, et al. (2014, https://doi.org/10.5194/acp-14-13043-2014) has the best agreement with dust extinction profiles and DOD from L15 in the Taklamakan desert and Tibetan Plateau. CESM with the default dust emission scheme of Zender, Bian, and Newman (2003, https://doi.org/10.1029/2002JD002775) underpredicts DOD in the Tibetan Plateau compared with observations from L15 due to the underestimation of local dust emission. Large uncertainties exist in observations from L15, Y15, and CALIPSO level 3 products and have significant impacts on the model evaluation of dust spatial distributions. We also assess dust surface concentrations and 10-m wind speed with meteorological records from weather stations in the Taklamakan and Gobi deserts during dust events. CESM underestimates dust surface concentrations at most weather stations due to the inability of CESM to capture strong surface wind events.