Increased Dust Aerosols in the High Troposphere Over the Tibetan Plateau From 1990s to 2000s

Dust aerosols are a major type of aerosol over the Tibetan Plateau (TP) and influence climate at local to regional scales through their effects on thermal radiation and snow-albedo feedback. Based on the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) aerosol data set, we report an increase of 34% in the atmospheric dust in the high troposphere over the TP during the spring season in the 2000s in comparison to the 1990s. This result is supported by an increase of 157% (46%) in the dust deposition flux in the Mugagangqiong (Tanggula) ice cores and an increase of 69% in the aerosol index (AI) from Earth Probe (EP) Total Ozone Mapping Spectrometer (TOMS), as well as by increases of simulated dust aerosols over the TP derived from the Community Earth System Model (CESM) and models from the Coupled Model Intercomparison Project Phase 6 (CMIP6). The increased atmospheric dust over the TP is caused by two aspects: (1) There was a higher dust emission over the Middle East during the 2000s than during the 1990s, which is explained by less precipitation and 25.8% higher cyclone frequency over the Middle East. The increased cyclone frequency uplift more dust from the surface over the Middle East to the central Asia in the middle troposphere. (2) Enhanced midlatitude zonal winds help transport more dust in the middle troposphere from central Asia to Northwest China, and thereafter, an increase in northerly winds over Northwest China propels dust southward to the TP.