Where does the dust deposited over the Sierra Nevada snow come from?

[摘要] Mineral dust contributes up to one-half of surface aerosol loading in springover the southwestern United States, posing an environmental challenge that threatenshuman health and the ecosystem. Using self-organizing map (SOM) analysiswith dust deposition and flux data from WRF-Chem and Modern-EraRetrospective analysis for Research and Applications, Version 2 (MERRA-2),we identify four typical dust transport patterns across the Sierra Nevada,associated with the mesoscale winds, Sierra barrier jet (SBJ),North Pacific High (NPH), and long-range cross-Pacific westerlies,respectively. We find that dust emitted from the Central Valley ispersistently transported eastward, while dust from the Mojave Desert andGreat Basin influences the Sierra Nevada during mesoscale transportoccurring mostly in winter and early spring. Asian dust reaching themountain range comes either from the west through straight isobars(cross-Pacific transport) or from the north in the presence of the NPH.Extensive dust depositions are found on the west slope of the mountain,contributed by Central Valley emissions and cross-Pacific remote transport.In particular, the SBJ-related transport produces deposition throughlandfalling atmospheric rivers, whose frequency might increase in a warmingclimate.

[学科分类] 医学（综合）