In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 21, No. 10 ( 2021-05-27), p. 8169-8193
Abstract:
Abstract. Even though desert dust is the most abundant aerosol by
mass in Earth's atmosphere, the relative contributions of the world's major
source regions to the global dust cycle remain poorly constrained. This
problem hinders accounting for the potentially large impact of regional
differences in dust properties on clouds, the Earth's energy balance, and
terrestrial and marine biogeochemical cycles. Here, we constrain the
contribution of each of the world's main dust source regions to the global
dust cycle. We use an analytical framework that integrates an ensemble of
global aerosol model simulations with observationally informed constraints
on the dust size distribution, extinction efficiency, and regional dust
aerosol optical depth (DAOD). We obtain a dataset that constrains the
relative contribution of nine major source regions to size-resolved
dust emission, atmospheric loading, DAOD, concentration, and deposition
flux. We find that the 22–29 Tg (1 standard error range) global loading of
dust 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 North
American and Southern Hemisphere regions contribute ∼ 10 %
(1.8–3.2 Tg). These results suggest that current models on average
overestimate the contribution of North African sources to atmospheric dust
loading at ∼ 65 %, while underestimating the contribution of
Asian dust at ∼ 30 %. Our results further show that each
source region's dust loading peaks in local spring and summer, which is
partially driven by increased dust lifetime in those seasons. We also
quantify the dust deposition flux to the Amazon rainforest to be
∼ 10 Tg yr−1, which is a factor of 2–3 less than inferred from
satellite data by previous work that likely overestimated dust deposition by
underestimating the dust mass extinction efficiency. The data obtained in
this paper can be used to obtain improved constraints on dust impacts on
clouds, climate, biogeochemical cycles, and other parts of the Earth system.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-21-8169-2021
DOI:
10.5194/acp-21-8169-2021-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
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