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 by mass in Earth's atmosphere, the relative contributions of the world’s major dust 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 model simulations with observationally informed constraints on the dust size distribution, extinction efficiency, and regional dust aerosol optical depth. We obtain a data set that constrains the relative contribution of each of nine major source regions to size-resolved dust emission, atmospheric loading, optical depth, concentration, and deposition flux. We find that the 22–29 Tg (one standard error range) global loading of dust with 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). Current models might on average be overestimating the contribution of North African sources to atmospheric dust loading at ~65 %, while underestimating the contribution of Asian dust at ~30 %. However, both our results and current models could be affected by unquantified biases, such as due to errors in separating dust aerosol optical depth from that produced by other aerosol species in remote sensing retrievals in poorly observed desert regions. 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/year, 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.

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Contribution of the world's main dust source regions to the global cycle of desert dust

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-8169-2021 ◽

2021 ◽

Vol 21 (10) ◽

pp. 8169-8193

Author(s):

Jasper F. Kok ◽

Adeyemi A. Adebiyi ◽

Samuel Albani ◽

Yves Balkanski ◽

Ramiro Checa-Garcia ◽

...

Keyword(s):

Biogeochemical Cycles ◽

Deposition Flux ◽

Dust Deposition ◽

North African ◽

Dust Source ◽

Aerosol Model ◽

Desert Dust ◽

Extinction Efficiency ◽

Source Regions ◽

Dust Loading

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.

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Application of a satellite-based aridity index in dust source regions of northeast Asia

Journal of Arid Environments ◽

10.1016/j.jaridenv.2014.05.007 ◽

2014 ◽

Vol 109 ◽

pp. 31-38 ◽

Cited By ~ 7

Author(s):

Reiji Kimura ◽

Masao Moriyama

Keyword(s):

Northeast Asia ◽

Aridity Index ◽

Dust Source ◽

Source Regions

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Seasonal provenance changes in present-day Saharan dust collected in and off Mauritania

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-10163-2017 ◽

2017 ◽

Vol 17 (16) ◽

pp. 10163-10193 ◽

Cited By ~ 4

Author(s):

Carmen A. Friese ◽

Johannes A. van Hateren ◽

Christoph Vogt ◽

Gerhard Fischer ◽

Jan-Berend W. Stuut

Keyword(s):

Environmental Changes ◽

Saharan Dust ◽

Local Source ◽

Trade Wind ◽

Back Trajectory ◽

Dust Source ◽

Western Sahara ◽

Source Areas ◽

Source Regions ◽

Dust Sources

Abstract. Saharan dust has a crucial influence on the earth climate system and its emission, transport and deposition are intimately related to, e.g., wind speed, precipitation, temperature and vegetation cover. The alteration in the physical and chemical properties of Saharan dust due to environmental changes is often used to reconstruct the climate of the past. However, to better interpret possible climate changes the dust source regions need to be known. By analysing the mineralogical composition of transported or deposited dust, potential dust source areas can be inferred. Summer dust transport off northwest Africa occurs in the Saharan air layer (SAL). In continental dust source areas, dust is also transported in the SAL; however, the predominant dust input occurs from nearby dust sources with the low-level trade winds. Hence, the source regions and related mineralogical tracers differ with season and sampling location. To test this, dust collected in traps onshore and in oceanic sediment traps off Mauritania during 2013 to 2015 was analysed. Meteorological data, particle-size distributions, back-trajectory and mineralogical analyses were compared to derive the dust provenance and dispersal. For the onshore dust samples, the source regions varied according to the seasonal changes in trade-wind direction. Gibbsite and dolomite indicated a Western Saharan and local source during summer, while chlorite, serpentine and rutile indicated a source in Mauritania and Mali during winter. In contrast, for the samples that were collected offshore, dust sources varied according to the seasonal change in the dust transporting air layer. In summer, dust was transported in the SAL from Mauritania, Mali and Libya as indicated by ferroglaucophane and zeolite. In winter, dust was transported with the trades from Western Sahara as indicated by, e.g., fluellite.

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African dust source regions for observed dust outbreaks over the Subtropical Eastern North Atlantic region, above 25°N

Journal of Arid Environments ◽

10.1016/j.jaridenv.2011.11.013 ◽

2012 ◽

Vol 78 ◽

pp. 100-109 ◽

Cited By ~ 21

Author(s):

S. Alonso-Pérez ◽

E. Cuevas ◽

X. Querol ◽

J.C. Guerra ◽

C. Pérez

Keyword(s):

North Atlantic ◽

North Atlantic Region ◽

Atlantic Region ◽

Dust Source ◽

African Dust ◽

Source Regions ◽

Eastern North Atlantic

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Identification and Characterization of Dust Source Regions Across North Africa and the Middle East Using MISR Satellite Observations

Geophysical Research Letters ◽

10.1029/2018gl078324 ◽

2018 ◽

Vol 45 (13) ◽

pp. 6690-6701 ◽

Cited By ~ 11

Author(s):

Yan Yu ◽

Olga V. Kalashnikova ◽

Michael J. Garay ◽

Huikyo Lee ◽

Michael Notaro

Keyword(s):

Middle East ◽

North Africa ◽

Satellite Observations ◽

Dust Source ◽

Source Regions ◽

Identification And Characterization

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Performance of KMA-ADAM3 in Identifying Asian Dust Days over Northern China

Atmosphere ◽

10.3390/atmos11060593 ◽

2020 ◽

Vol 11 (6) ◽

pp. 593

Author(s):

Sang-Boom Ryoo ◽

Jinwon Kim ◽

Jeong Hoon Cho

Keyword(s):

Dust Emission ◽

Northern China ◽

Asian Dust ◽

Probability Of Detection ◽

Soil Types ◽

Dust Source ◽

Aerosol Model ◽

Dust Generation ◽

Source Regions ◽

Dust Events

Recently, the Korea Meteorological Administration developed Asian Dust Aerosol Model version 3 (ADAM3) by incorporating additional parameters into ADAM2, including anthropogenic particulate matter (PM) emissions, modification of dust generation by considering real-time surface vegetation, and assimilations of surface PM observations and satellite-measured aerosol optical depth. This study evaluates the performance of ADAM3 in identifying Asian dust days over the dust source regions in Northern China and their variations according to regions and soil types by comparing its performance with ADAM2 (from January to June of 2017). In all regions the performance of ADAM3 was markedly improved, especially for Northwestern China, where the threat score (TS) and the probability of detection (POD) improved from 5.4% and 5.5% to 30.4% and 34.4%, respectively. ADAM3 outperforms ADAM2 for all soil types, especially for the sand-type soil for which TS and POD are improved from 39.2.0% and 50.7% to 48.9% and 68.2%, respectively. Despite these improvements in regions and surface soil types, Asian dust emission formulas in ADAM3 need improvement for the loess-type soils to modulate the overestimation of Asian dust events related to anthropogenic emissions in the Huabei Plain and Manchuria.

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Dust vertical profile impact on global radiative forcing estimation using a coupled chemical-transport–radiative-transfer model

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-7097-2013 ◽

2013 ◽

Vol 13 (14) ◽

pp. 7097-7114 ◽

Cited By ~ 35

Author(s):

L. Zhang ◽

Q. B. Li ◽

Y. Gu ◽

K. N. Liou ◽

B. Meland

Keyword(s):

Heating Rate ◽

Vertical Profile ◽

Radiative Forcing ◽

Asian Dust ◽

Dust Particles ◽

Radiative Transfer Model ◽

Transfer Model ◽

Vertical Profiles ◽

Dust Source ◽

Source Regions

Abstract. Atmospheric mineral dust particles exert significant direct radiative forcings and are important drivers of climate and climate change. We used the GEOS-Chem global three-dimensional chemical transport model (CTM) coupled with the Fu-Liou-Gu (FLG) radiative transfer model (RTM) to investigate the dust radiative forcing and heating rate based on different vertical profiles for April 2006. We attempt to actually quantify the sensitivities of radiative forcing to dust vertical profiles, especially the discrepancies between using realistic and climatological vertical profiles. In these calculations, dust emissions were constrained by observations of aerosol optical depth (AOD). The coupled calculations utilizing a more realistic dust vertical profile simulated by GEOS-Chem minimize the physical inconsistencies between 3-D CTM aerosol fields and the RTM. The use of GEOS-Chem simulated vertical profile of dust extinction, as opposed to the FLG prescribed vertical profile, leads to greater and more spatially heterogeneous changes in the estimated radiative forcing and heating rate produced by dust. Both changes can be attributed to a different vertical structure between dust and non-dust source regions. Values of the dust vertically resolved AOD per grid level (VRAOD) are much larger in the middle troposphere, though smaller at the surface when the GEOS-Chem simulated vertical profile is used, which leads to a much stronger heating rate in the middle troposphere. Compared to the FLG vertical profile, the use of GEOS-Chem vertical profile reduces the solar radiative forcing at the top of atmosphere (TOA) by approximately 0.2–0.25 W m−2 over the African and Asian dust source regions. While the Infrared (IR) radiative forcing decreases 0.2 W m−2 over African dust belt, it increases 0.06 W m−2 over the Asian dust belt when the GEOS-Chem vertical profile is used. Differences in the solar radiative forcing at the surface between the use of the GEOS-Chem and FLG vertical profiles are most significant over the Gobi desert with a value of about 1.1 W m−2. The radiative forcing effect of dust particles is more pronounced at the surface over the Sahara and Gobi deserts by using FLG vertical profile, while it is less significant over the downwind area of Eastern Asia.

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