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Title: Contribution of the world's main dust source regions to the global cycle of desert dust
Abstract. Even though desert dust is the most abundant aerosol bymass in Earth's atmosphere, the relative contributions of the world's majorsource regions to the global dust cycle remain poorly constrained. Thisproblem hinders accounting for the potentially large impact of regionaldifferences in dust properties on clouds, the Earth's energy balance, andterrestrial and marine biogeochemical cycles. Here, we constrain thecontribution of each of the world's main dust source regions to the globaldust cycle. We use an analytical framework that integrates an ensemble ofglobal aerosol model simulations with observationally informed constraintson the dust size distribution, extinction efficiency, and regional dustaerosol optical depth (DAOD). We obtain a dataset that constrains therelative contribution of nine major source regions to size-resolveddust emission, atmospheric loading, DAOD, concentration, and depositionflux. We find that the 22–29 Tg (1 standard error range) global loading ofdust with a geometric diameter up to 20 µm is partitioned as follows:North African source regions contribute ∼ 50 % (11–15 Tg),Asian source regions contribute ∼ 40 % (8–13 Tg), and NorthAmerican and Southern Hemisphere regions contribute ∼ 10 %(1.8–3.2 Tg). These results suggest that current models on averageoverestimate the contribution of North African sources to atmospheric dustloading at ∼ 65 %, while underestimating the contribution ofAsian dust at ∼ 30 %. Our results further show that eachsource region's dust loading peaks in local spring and summer, which ispartially driven by increased dust lifetime in those seasons. We alsoquantify the dust deposition flux to the Amazon rainforest to be∼ 10 Tg yr−1, which is a factor of 2–3 less than inferred fromsatellite data by previous work that likely overestimated dust deposition byunderestimating the dust mass extinction efficiency. The data obtained inthis paper can be used to obtain improved constraints on dust impacts onclouds, climate, biogeochemical cycles, and other parts of the Earth system.  more » « less
Award ID(s):
1856389
PAR ID:
10231752
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Atmospheric Chemistry and Physics
Volume:
21
Issue:
10
ISSN:
1680-7324
Page Range / eLocation ID:
8169 to 8193
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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