scholarly journals 14 kyr of atmospheric mineral dust deposition in north-eastern China: A record of palaeoclimatic and palaeoenvironmental changes in the Chinese dust source regions

The Holocene ◽  
2019 ◽  
Vol 30 (4) ◽  
pp. 492-506 ◽  
Author(s):  
Steve Pratte ◽  
Kunshan Bao ◽  
Atindra Sapkota ◽  
Wenfang Zhang ◽  
Ji Shen ◽  
...  
Keyword(s):  
Late Holocene ◽  
Mineral Dust ◽  
East Asian ◽  
Eastern China ◽  
Dust Deposition ◽  
Dust Source ◽  
Principal Mechanism ◽  
Middle Holocene ◽  
Source Regions ◽  
North Eastern

A multi-proxy record of Holocene and late-Pleistocene aeolian mineral dust is reconstructed using a combination of geochemical (trace elements), mineralogical and grain-size analyses on cores from the Hani peatland in north-eastern (NE) China. The dust record displays a sharp increase in dust deposition during the late Holocene in comparison to the rest of the Holocene. This trend is in line with climatic records from the Chinese dust source regions and their downwind areas, which generally show an increase in aridity and aeolian activity during the late Holocene. The larger part of the Chinese dust source regions experienced a gradual increase in effective moisture and vegetation cover reaching maxima during the middle Holocene (6.0–8.0 kyr cal. BP) co-occurring with the minima in dust deposition in Hani. These changes in the dust source regions are likely to have been modulated by the variations in the East Asian summer monsoon (EASM), which is the principal mechanism controlling climate in the region. The intensified EASM during the middle Holocene is also likely to have resulted in a sediment recharge at the margin of the Chinese drylands providing additional material and enhancing the atmospheric dust load after the late-Holocene aridification of the region. Combined together, these changes promoted a remobilization of dust sources increasing the amount of material available for transport by the East Asian winter monsoon (EAWM) and the Westerlies. Human activities might also have played a role in the increased dust emissions during the late Holocene, but further research is needed to assess the extent of those impacts at a regional level.

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

2021 ◽  
Author(s):  
Jasper F. Kok ◽  
Adeyemi A. Adebiyi ◽  
Samuel Albani ◽  
Yves Balkanski ◽  
Ramiro Checa-Garcia ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Biogeochemical Cycles ◽  
Deposition Flux ◽  
Dust Deposition ◽  
North African ◽  
Dust Source ◽  
Desert Dust ◽  
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 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.

Dust deposition tracks late-Holocene shifts in monsoon activity and the increasing role of human disturbance in the Puna-Altiplano, northwest Argentina

The Holocene ◽  
2020 ◽  
Vol 30 (4) ◽  
pp. 519-536 ◽  
Author(s):  
James Hooper ◽  
Samuel K Marx ◽  
Jan-Hendrik May ◽  
Liliana C Lupo ◽  
Julio J Kulemeyer ◽  
...  
Keyword(s):  
Late Holocene ◽  
Human Impacts ◽  
South American ◽  
Dust Deposition ◽  
The South ◽  
Dust Source ◽  
Dust Emissions ◽  
Dust Flux ◽  
Dry Conditions

The Puna-Altiplano plateau represents a regionally significant dust source, which is critically located at the nexus between the tropical and sub-polar synoptic systems that dominate the South American climate. Dust emissions in this region would therefore be expected to be sensitive to changes in these systems, in particular the strength and position of the South American Summer Monsoon (SASM). Here, we present a late-Holocene multi-proxy study where changes in dust flux, reconstructed from a high-altitude peat mire, are examined in light of climate variability and human impacts. Results show that for most the 4300 cal. yr BP record, dust flux sensitively tracked changes in SASM activity. Prior to 2600 cal. yr BP relatively high dust flux implies dry conditions prevailed across the Puna-Altiplao in association with reduced SASM activity. The chemistry of dust deposited at this time matched the large endorheic basins on the Puna, which host ephemeral lakes and terminal fans, indicating these were actively supplying dust to the airstream. After 2600 cal. yr BP, SASM activity increased while dust flux decreased and the dust chemistry changed, collectively implying the shutting down of the Puna-Altiplano as a significant dust source. Dust flux increased after 1000 cal. yr BP during the ‘Medieval Warm Period’, associated with a return to drier conditions and reactivation of dust sources across the endorheic basins of the Puna. Natural variability in dust flux was dwarfed, however, by the very significant increase in flux after 400 cal. yr BP following Spanish Colonisation and associated changing landuse practices. This finding attests to the globally significant role of humans on dust emissions.

scholarly journals Optical and microphysical properties of natural mineral dust and anthropogenic soil dust near dust source regions over northwestern China

2018 ◽  
Vol 18 (3) ◽  
pp. 2119-2138 ◽  
Author(s):  
Xin Wang ◽  
Hui Wen ◽  
Jinsen Shi ◽  
Jianrong Bi ◽  
Zhongwei Huang ◽  
...  
Keyword(s):  
Atmospheric Aerosols ◽  
Mineral Dust ◽  
Particle Diameter ◽  
Northwestern China ◽  
Soil Dust ◽  
Dust Source ◽  
Dust Aerosols ◽  
Microphysical Properties ◽  
Source Regions ◽  
Anthropogenic Soil

Abstract. Mineral dust aerosols (MDs) not only influence the climate by scattering and absorbing solar radiation but also modify cloud properties and change the ecosystem. From 3 April to 16 May 2014, a ground-based mobile laboratory was deployed to measure the optical and microphysical properties of MDs near dust source regions in Wuwei, Zhangye, and Dunhuang (in chronological order) along the Hexi Corridor over northwestern China. Throughout this dust campaign, the hourly averaged (±standard deviation) aerosol scattering coefficients (σsp, 550 nm) of the particulates with aerodynamic diameters less than 2.5 µm (PM2.5) at these three sites were sequentially 101.5 ± 36.8, 182.2 ± 433.1, and 54.0 ± 32.0 Mm−1. Correspondingly, the absorption coefficients (σap, 637 nm) were 9.7 ± 6.1, 6.0 ± 4.6, and 2.3 ± 0.9 Mm−1; single-scattering albedos (ω, 637 nm) were 0.902 ± 0.025, 0.931 ± 0.037, and 0.949 ± 0.020; and scattering Ångström exponents (Åsp, 450–700 nm) of PM2.5 were 1.28 ± 0.27, 0.77 ± 0.51, and 0.52 ± 0.31. During a severe dust storm in Zhangye (i.e., from 23 to 25 April), the highest values of σsp2.5 (∼ 5074 Mm−1), backscattering coefficient (σbsp2.5, ∼ 522 Mm−1), and ω637 (∼ 0.993) and the lowest values of backscattering fraction (b2.5, ∼ 0.101) at 550 nm and Åsp2.5 (∼ −0.046) at 450–700 nm, with peak values of aerosol number size distribution (appearing at the particle diameter range of 1–3 µm), exhibited that the atmospheric aerosols were dominated by coarse-mode dust aerosols. It is hypothesized that the relatively higher values of mass scattering efficiency during floating dust episodes in Wuwei and Zhangye are attributed to the anthropogenic soil dust produced by agricultural cultivations.

scholarly journals The GESAMP atmospheric iron deposition model intercomparison study

2018 ◽  
Author(s):  
Stelios Myriokefalitakis ◽  
Akinori Ito ◽  
Maria Kanakidou ◽  
Athanasios Nenes ◽  
Maarten C. Krol ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Global Ocean ◽  
Current Status ◽  
Aerosol Size Distribution ◽  
Model Intercomparison ◽  
Dust Source ◽  
Deposition Fluxes ◽  
Source Regions ◽  
Atmospheric Processing ◽  
The Mean

Abstract. This work reports on the current status of global modelling of iron (Fe) deposition fluxes and atmospheric concentrations and analyses of the differences between models, as well as between models and observations. A total of four global 3-D chemistry-transport (CTMs) and general circulation (GCMs) models have participated in this intercomparison, in the framework of the United Nations Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) Working Group 38, The Atmospheric Input of Chemicals to the Ocean. The global total Fe (TFe) emissions strength in the models is equal to ~ 72 Tg-Fe yr−1 (38–134 Tg-Fe yr−1) from mineral dust sources and around 2.1 Tg-Fe yr−1 (1.8–2.7 Tg-Fe yr−1) from combustion processes (sum of anthropogenic combustion/biomass burning and wildfires). The mean global labile Fe (LFe) source strength in the models, considering both the primary emissions and the atmospheric processing, is calculated to be 0.7 (±0.3) Tg-Fe yr−1, accounting for mineral dust and combustion aerosols together. The multi model ensemble global TFe and LFe deposition fluxes into the global ocean are calculated to be ~ 15 Tg-Fe yr−1 and ~ 0.3 Tg-Fe yr−1, respectively. The model intercomparison analysis indicates that the representation of the atmospheric Fe cycle varies among models, in terms of both the magnitude of natural and combustion Fe emissions as well as the complexity of atmospheric processing parametrizations of Fe-containing aerosols. The model comparison with aerosol Fe observations over oceanic regions indicate that most models overestimate surface level TFe mass concentrations near the dust source regions and tend to underestimate the low concentrations observed in remote ocean regions. All models are able to simulate the tendency of higher Fe loading near and downwind from the dust source regions, with the mean normalized bias for the Northern Hemisphere (~ 14), larger than the Southern Hemisphere (~ 2.4) for the ensemble model mean. This model intercomparison and model–observation comparison study reveals two critical issues in LFe simulations that require further exploration: 1) the Fe-containing aerosol size distribution and 2) the relative contribution of dust and combustion sources of Fe to labile Fe in atmospheric aerosols over the remote oceanic regions.

Coarse-grained mineral dust deposition in alpine lakes provide evidence of increased windspeeds associated with more intense cyclogenesis during warmer intervals of the late Holocene period in arid and semi-arid tracts of North America.

2020 ◽  
Author(s):  
Atreyee Bhattacharya ◽  
Anne Bennett ◽  
Thomas Marchitto ◽  
Elana Leithold
Keyword(s):  
Grain Size ◽  
North America ◽  
Late Holocene ◽  
Mineral Dust ◽  
Fine Fraction ◽  
Dust Deposition ◽  
Size Fractions ◽  
Grain Sizes ◽  
Dust Generation ◽  
Semi Arid

<p>Mineral dust accumulation is often causally associated with aridity, with higher dust deposition rates are assumed to reflect increasing magnitude of aridity. However, the relation between dust deposition and aridity is not straightforward; grain sizes play a crucial role in processes associated with mineral dust generation, transportation and deposition in sedimentary settings.</p><p>In this study, we apply grain-size analyses in six well-studied cores (spanning the late Holocene) previously collected from alpine lake sites distributed across the arid and semi-arid regions of west, southwest, and the Great Plains of North America. Previous work with these cores has demonstrated that the lake sediments are predominantly detrital, windblown particles and little to no impact of fluvial proceeses . We find that the most commonly occurring grain sizes are a fine fraction (typically <4 microns, which is easily lofted and transported long distances) and a coarse fraction (typically >25 microns and in some cases with a distinct peak at 100 microns, both of which are are too large to be carried long distances and suggest short distance transportation). We used grain size separation techniques to separate the two size fractions and geochemically fingerprinted those from three sites.</p><p>We find that more rapid accumulation of the coarser coarser-grain size fractions occurred during wetter intervals in the Holocene. Furthermore, the geochemistry of the coarse fractions indicates regional rather than local sourcing of the material from bedrock weathering. We do not find any clear relationships between the fine fraction and aridity patterns, nor a clear source region for this material.</p><p>We hypothesize that the increase in coarser dust deposition during wetter intervals is related to either intensification of land-use patterns associated with agriculture and/or to episodically strong winds. Warmer and wetter intervals in the areas under consideration have been associated with intensified cyclogenesis. Our study demonstrates the critical need to incorporate grain-size analysis as well as geochemical fingerprinting of the different size fractions in interpreting mineral dust record.</p><p> </p><p>Acknowledgement: James Sickman, Jason Neff (for sharing samples), Jacob Ashford, Tyler Vollmer, Audriana Pollen, Alejandra Pedrazza, (for assistance with analyses and archival visits), John Morton, Wendy Freeman (for assisting students in the laboratory), Aradhna Tripati and Juan Lora (for assisting with data interpretation).</p><p> </p>

scholarly journals Reviews and syntheses: the GESAMP atmospheric iron deposition model intercomparison study

2018 ◽  
Vol 15 (21) ◽  
pp. 6659-6684 ◽  
Author(s):  
Stelios Myriokefalitakis ◽  
Akinori Ito ◽  
Maria Kanakidou ◽  
Athanasios Nenes ◽  
Maarten C. Krol ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Global Ocean ◽  
Aerosol Size Distribution ◽  
Ensemble Model ◽  
Model Intercomparison ◽  
Dust Source ◽  
Deposition Fluxes ◽  
Source Regions ◽  
Atmospheric Processing ◽  
The Mean

Abstract. This work reports on the current status of the global modeling of iron (Fe) deposition fluxes and atmospheric concentrations and the analyses of the differences between models, as well as between models and observations. A total of four global 3-D chemistry transport (CTMs) and general circulation (GCMs) models participated in this intercomparison, in the framework of the United Nations Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) Working Group 38, “The Atmospheric Input of Chemicals to the Ocean”. The global total Fe (TFe) emission strength in the models is equal to ∼72 Tg Fe yr−1 (38–134 Tg Fe yr−1) from mineral dust sources and around 2.1 Tg Fe yr−1 (1.8–2.7 Tg Fe yr−1) from combustion processes (the sum of anthropogenic combustion/biomass burning and wildfires). The mean global labile Fe (LFe) source strength in the models, considering both the primary emissions and the atmospheric processing, is calculated to be 0.7 (±0.3) Tg Fe yr−1, accounting for both mineral dust and combustion aerosols. The mean global deposition fluxes into the global ocean are estimated to be in the range of 10–30 and 0.2–0.4 Tg Fe yr−1 for TFe and LFe, respectively, which roughly corresponds to a respective 15 and 0.3 Tg Fe yr−1 for the multi-model ensemble model mean. The model intercomparison analysis indicates that the representation of the atmospheric Fe cycle varies among models, in terms of both the magnitude of natural and combustion Fe emissions as well as the complexity of atmospheric processing parameterizations of Fe-containing aerosols. The model comparison with aerosol Fe observations over oceanic regions indicates that most models overestimate surface level TFe mass concentrations near dust source regions and tend to underestimate the low concentrations observed in remote ocean regions. All models are able to simulate the tendency of higher Fe concentrations near and downwind from the dust source regions, with the mean normalized bias for the Northern Hemisphere (∼14), larger than that of the Southern Hemisphere (∼2.4) for the ensemble model mean. This model intercomparison and model–observation comparison study reveals two critical issues in LFe simulations that require further exploration: (1) the Fe-containing aerosol size distribution and (2) the relative contribution of dust and combustion sources of Fe to labile Fe in atmospheric aerosols over the remote oceanic regions.

scholarly journals Development of a global model of mineral dust aerosol microphysics

2008 ◽  
Vol 8 (6) ◽  
pp. 18765-18802
Author(s):  
Y. H. Lee ◽  
K. Chen ◽  
P. J. Adams
Keyword(s):  
Mineral Dust ◽  
Dust Particles ◽  
Base Case ◽  
Dust Source ◽  
Deposition Fluxes ◽  
Surface Mass ◽  
Remote Areas ◽  
Source Regions ◽  
Mass Concentrations

Abstract. A mineral dust module is developed and implemented into the global aerosol microphysics model, GISS-TOMAS. The model is evaluated against long-term measurements of dust surface mass concentrations and deposition fluxes. Predicted mass concentrations and deposition fluxes are in error on average by a factor of 3 and 5, respectively. The comparison shows that the model performs better near the dust source regions but underestimates surface concentrations and deposition fluxes in more remote regions. For example, including only sites with measured dust concentrations of at least 0.5 μg m−3, the model prediction agrees with observations to within a factor of 2. It was hypothesized that the lifetime of dust, 2.6 days in our base case, is too short and causes the underestimation in remote areas. However, a sensitivity simulation with smaller dust particles and increased lifetime, 3.7 days, does not significantly improve the comparison. We conclude that the underestimation of mineral dust in remote areas results from local factors and sources not well described by the dust source function and/or the GCM meteorology. The effect of dust aerosols on CCN(0.2%) concentrations is negligible in most regions of the globe; however, CCN(0.2%) concentrations decrease by 10–20% in dusty regions as a result of coagulational scavenging of CCN particles by dust and a decrease in H2SO4 condensation to CCN particles due to the additional surface area of dust.

scholarly journals Development of a global model of mineral dust aerosol microphysics

2009 ◽  
Vol 9 (7) ◽  
pp. 2441-2458 ◽  
Author(s):  
Y. H. Lee ◽  
K. Chen ◽  
P. J. Adams
Keyword(s):  
Mineral Dust ◽  
Dust Particles ◽  
Base Case ◽  
Dust Source ◽  
Deposition Fluxes ◽  
Surface Mass ◽  
Remote Areas ◽  
Source Regions ◽  
The Impact ◽  
Mass Concentrations

Abstract. A mineral dust module is developed and implemented into the global aerosol microphysics model, GISS-TOMAS. The model is evaluated against long-term measurements of dust surface mass concentrations and deposition fluxes. Predicted mass concentrations and deposition fluxes are in error on average by a factor of 3 and 5, respectively. The comparison shows that the model performs better near the dust source regions but underestimates surface concentrations and deposition fluxes in more remote regions. Including only sites with measured dust concentrations of at least 0.5 μg m−3, the model prediction agrees with observations to within a factor of 2. It was hypothesized that the lifetime of dust, 2.6 days in our base case, is too short and causes the underestimation in remote areas. However, a sensitivity simulation with smaller dust particles and increased lifetime, 3.7 days, does not significantly improve the comparison. These results suggest that the underestimation of mineral dust in remote areas may result from local factors/sources not well described by the global dust source function used here or the GCM meteorology. The effect of dust aerosols on CCN(0.2%) concentrations is negligible in most regions of the globe; however, CCN(0.2%) concentrations change decrease by 10–20% in dusty regions the impact of dust on CCN(0.2%) concentrations in dusty regions is very sensitive to the assumed size distribution of emissions. If emissions are predominantly in the coarse mode, CCN(0.2%) decreases in dusty regions up to 10–20% because dust competes for condensable H2SO4, reducing the condensational growth of ultrafine mode particles to CCN sizes. With significant fine mode emissions, however, CCN(0.2%) doubles in Saharan source regions because the direct emission of dust particles outweighs any microphysical feedbacks. The impact of dust on CCN concentrations active at various water supersaturations is also investigated. Below 0.1%, CCN concentrations increase significantly in dusty regions due to the presence of coarse dust particles. Above 0.2%, CCN concentrations show a similar behavior as CCN(0.2%).

Sign in / Sign up

Export Citation Format

Share Document