Evaluation of dust emission and transport simulated by global climate models with satellite observations from CALIOP, MODIS, and MISR

Wednesday, December 11, 2019 - 08:00
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Dust aerosols are important in modulating the climate system at local and global scales. In this study, we evaluate the spatio-temporal variations of dust extinction profiles and dust optical depth (DOD) simulated from the Community Earth System Model version 1 (CESM1) and version 2 (CESM2), the Energy Exascale Earth System Model version 1 (E3SMv1), and the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) with satellite retrievals from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), Moderate Resolution Imaging Spectroradiometer (MODIS), and Multi-angle Imaging SpectroRadiometer (MISR). CESM1, CESM2, and E3SMv1 use the dust emission scheme of Zender et al. (2003), while MERRA-2 uses the dust emission scheme of Ginoux et al. (2001). The mass fraction of emitted fine mode dust is vastly different among these models. We find that CESM1, CESM2, and E3SMv1 underestimate dust transport to remote regions. Modeled DOD over ocean in CESM1, CESM2, and E3SMv1 is much lower than observations, resulting in a substantial low model bias of global annual mean DOD. E3SMv1 improves dust transport and performs better than CESM1 and CESM2 in simulating DOD of the northern hemisphere (NH) due to a higher mass fraction of fine dust. CESM2 performs the worst in the NH due to low dust emission but improves dust simulation in the southern hemisphere (SH) due to overestimation of dust emission in the SH. MERRA-2 agrees well with CALIOP DOD in remote regions due to high mass fraction of fine dust and the data assimilation. There are also large disagreements in the dust extinction profiles and DOD among CALIOP, MODIS, and MISR retrievals, which have significant impacts on the model evaluation of dust spatial distributions.

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