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Aeolian Processes and Geomorphology

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A special issue of Geosciences (ISSN 2076-3263). This special issue belongs to the section "Sedimentology, Stratigraphy and Palaeontology".

Deadline for manuscript submissions: closed (30 June 2018) | Viewed by 78288

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Special Issue Editor

Dr. Eric J. R. Parteli

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Guest Editor

Faculty of Physics, University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, Germany
Interests: granular materials; aeolian processes; planetary geomorphology; physics of complex systems

Special Issue Information

Dear Colleagues,

This Special Issue is dedicated to recent progress in our understanding of aeolian processes—the emission, transport and deposition of dust and sand particles by wind—and the concatenated geomorphology of Earth and extra-terrestrial environments.

Wind-blown particles shape a substantial portion of the surface of our planet, and play a major role for weather, climate, and several other components of the Earth system. Airborne dust particles can be transported over thousands of kilometers from their source, thereby affecting the hydrological cycle, ecosystem productivity and human health. Moreover, wind-blown sand erodes rocks and soils, and creates a broad range of aeolian bedforms, including migrating ripples, megaripples and dunes, which are largely responsible for the morphodynamics of Earth’s deserts and coasts. Aeolian sand plays an important role for the propagation of desertification, which contributes to increase global warming and enhance poverty in many countries of the Earth.

The understanding of aeolian processes and their geomorphological implications has impact not only in the research of Earth’s climate and geology, but also in the planetary science. Aeolian dust research may help understand climate processes on Mars, where large dust storms obscuring the Sun over entire regions of the planet for several days at a time have been detected at different occasions since the first missions sent to the red planet. Moreover, aeolian bedforms are widespread on Mars, and occur also on Venus, Saturn’s moon Titan and the comet 67P/Churyumov-Gerasimenko. Images sent by New Horizons revealed that wind-blown particles have helped to shape the complex geology of the surface of Pluto as well. Bedform morphology and migration rates can serve as proxy for wind regimes, as well as attributes of sediment and atmosphere in extra-terrestrial environments. However, the accurate prediction of aeolian sediment fluxes and dune morphodynamics in such environments still poses one of the biggest challenges in planetary aeolian geomorphology.

Manuscripts in this Special Issue report progress in our understanding of aeolian transport of sand and the resulting landforms, the emission, transport and deposition of dust as well as the impact of dust on the Earth’s system, the characteristics and impact of aeolian processes in extra-terrestrial worlds, as well as the application of aeolian dust and dune research in the investigation of paleoenvironments, dating of aeolian deposits and bedforms of the Pleistocene and Holocene. This Special Issue further aims at highlighting progress in our understanding of the interaction between aeolian processes and biota, the impact of anthropogenic influences on aeolian sediment dynamics, the development of large sand seas, the characteristics of dune sediments, aeolian snow particles and landforms, dune management, wind erosion on agricultural fields and the control of dust and drifting sand. Moreover, manuscripts in this Special Issue report advances in theoretical and numerical models, as well as the newest developments in field and laboratory techniques, to investigate aeolian particles and bedforms.

This Special Issue is open both for manuscripts reporting results from original research and for inspiring review articles, which include a critical overview of the state-of-the-art in the research field considered, as well as an outlook of open, challenging problems to be addressed in future work.

Dr. Eric J. R. Parteli
Guest Editor

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Keywords

aeolian processes and geomorphology
planetary aeolian processes
paleoenvironments
dune sediments
wind erosion
control of dust and drifting sand
advances in theory, numerical modeling, field and lab methods

Published Papers (13 papers)

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Research

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19 pages, 2379 KiB

Open AccessArticle

Aeolian Ripple Migration and Associated Creep Transport Rates

by Douglas J. Sherman, Pei Zhang, Raleigh L. Martin, Jean T. Ellis, Jasper F. Kok, Eugene J. Farrell and Bailiang Li

Geosciences 2019, 9(9), 389; https://doi.org/10.3390/geosciences9090389 - 05 Sep 2019

Cited by 13 | Viewed by 4317

Abstract

Wind-formed ripples are distinctive features of many sandy aeolian environments, and their development and migration are basic responses to sand transport via saltation. Using data from the literature and from original field experiments, we presented empirical models linking dimensionless migration rates, [...] Read more.

u_{r} / \sqrt{g d}

(

u_{r}

is the ripple migration speed,

g

is the gravity acceleration, and

d

is the grain diameter) with dimensionless shear velocity, u_*/u_*t (u_* is shear velocity and u_*t is fluid threshold shear velocity). Data from previous studies provided 34 usable cases from four wind tunnel experiments and 93 cases from two field experiments. Original data comprising 68 cases were obtained from sites in Ceará, Brazil (26) and California, USA (42), using combinations of sonic anemometry, sand traps, photogrammetry, and laser distance sensors and particle counters. The results supported earlier findings of distinctively different relationships between

u_{r} / \sqrt{g d}

and u_*/u_*t for wind tunnel and field data. With our data, we could also estimate the contribution of creep transport associated with ripple migration to total transport rates. We calculated ripple-creep transport for 1 ≤ u_*/u_*t ≤ 2.5 and found that this accounted for about 3.6% (standard deviation = 2.3%) of total transport. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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60 pages, 8324 KiB

Open AccessArticle

Character, Rates, and Environmental Significance of Holocene Dust Accumulation in Archaeological Hilltop Ruins in the Southern Levant

by Bernhard Lucke, Joel Roskin, Kim André Vanselow, Hendrik J. Bruins, Nizar Abu-Jaber, Katleen Deckers, Susanne Lindauer, Naomi Porat, Paula J. Reimer, Rupert Bäumler, Tali Erickson-Gini and Paula Kouki

Geosciences 2019, 9(4), 190; https://doi.org/10.3390/geosciences9040190 - 24 Apr 2019

Cited by 19 | Viewed by 4989

Abstract

Loess accumulated in the Negev desert during the Pleistocene and primary and secondary loess remains cover large parts of the landscape. Holocene loess deposits are however absent. This could be due low accumulation rates, lack of preservation, and higher erosion rates in comparison to the Pleistocene. This study hypothesized that archaeological ruins preserve Holocene dust. We studied soils developed on archaeological hilltop ruins in the Negev and the Petra region and compared them with local soils, paleosols, geological outcrops, and current dust. Seven statistically modeled grain size end-members were identified and demonstrate that the ruin soils in both regions consist of mixtures of local and remote sediment sources that differ from dust compositions deposited during current storms. This discrepancy is attributed to fixation processes connected with sediment-fixing agents such as vegetation, biocrusts, and/or clast pavements associated with vesicular layers. Average dust accretion rates in the ruins are estimated to be ~0.14 mm/a, suggesting that ~30% of the current dust that can be trapped with dry marble dust collectors has been stored in the ruin soils. Deposition amounts and grain sizes do not significantly correlate with wind intensity. However, precipitation may have contributed to dust accretion. A snowstorm in the Petra region delivered a significantly higher amount of sediment than rain or dry deposition. Snowfall dust had a unique particle size distribution relatively similar to the ruin soils. Wet deposition and snow might catalyze dust deposition and enhance fixation by fostering vegetation and crust formation. More frequent snowfall during the Pleistocene may have been an important mechanism of primary loess deposition in the southern Levant. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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20 pages, 7722 KiB

Open AccessArticle

Aeolian Material Migration in Transbaikalia (Asian Russia)

by Olga Bazhenova, Dmitrii Kobylkin and Elizaveta Tyumentseva

Geosciences 2019, 9(1), 41; https://doi.org/10.3390/geosciences9010041 - 14 Jan 2019

Cited by 3 | Viewed by 3882

Abstract

We revealed regional features of functioning of a large Transbaikalian aeolian morphodynamic system. Natural pre-conditions, current realities and factors of development of aeolian processes are investigated. The paper considers regularities of spatial distribution of deflation, transit, and aeolian accumulation zones. Main directions of aeolian migration of matter are determined. Pulsating nature of aeolian processes development in Holocene has been established. Identified are intrasecular cycles and Holocene dynamics of aeolian processes. We identified intrasecular (11, 27–35 years old), secular (80 year old) and Holocene (500, 2000 year old) cycles of aeolian process dynamics. The paper shows the influence of anthropogenic activity on the activation of aeolian migration of material for the historical period. It presents an overview of extreme aeolian events. Regionalization of Transbaikalia was carried out according to the degree of probable desertification of the territory due to development of aeolian processes. Areas of catastrophic manifestation of processes are highlighted. The results of long-term experimental observations of deflation and aeolian accumulation are presented. Particular attention is paid to the characteristics of the aeolian corridors. The important role of aeolian processes in the intensive material transport from Transbaikalia to the south and southeast to neighboring regions of Mongolia and China is shown. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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14 pages, 1353 KiB

Open AccessArticle

The Critical Role of the Boundary Layer Thickness for the Initiation of Aeolian Sediment Transport

by Thomas Pähtz, Manousos Valyrakis, Xiao-Hu Zhao and Zhen-Shan Li

Geosciences 2018, 8(9), 314; https://doi.org/10.3390/geosciences8090314 - 23 Aug 2018

Cited by 26 | Viewed by 4647

Abstract

Here, we propose a conceptual framework of Aeolian sediment transport initiation that includes the role of turbulence. Upon increasing the wind shear stress

τ

above a threshold value

τ_{t}^{'}

, particles resting at the bed surface begin to rock in their [...] Read more.

Here, we propose a conceptual framework of Aeolian sediment transport initiation that includes the role of turbulence. Upon increasing the wind shear stress

τ

above a threshold value

τ_{t}^{'}

, particles resting at the bed surface begin to rock in their pockets because the largest turbulent fluctuations of the instantaneous wind velocity above its mean value

\bar{u}

induce fluid torques that exceed resisting torques. Upon a slight further increase of

τ

, rocking turns into a rolling regime (i.e., rolling threshold

τ_{t} ≃ τ_{t}^{'}

) provided that the ratio between the integral time scale

T_{i} \propto δ / \bar{u}

(where

δ

is the boundary layer thickness) and the time

T_{e} \propto \sqrt{d / [(1 - 1 / s) g]}

required for entrainment (where d is the particle diameter and s the particle–air–density ratio) is sufficiently large. Rolling then evolves into mean-wind-sustained saltation transport provided that the mean wind is able to compensate energy losses from particle-bed rebounds. However, when

T_{i} / T_{e}

is too small, the threshold ratio scales as

τ_{t} / τ_{t}^{'} \propto T_{e} / T_{i} \propto s d^{2} / δ^{2}

, consistent with experiments. Because

δ / d

controls

T_{i} / T_{e}

and the relative amplitude of turbulent wind velocity fluctuations, we qualitatively predict that Aeolian sediment transport in natural atmospheres can be initiated under weaker (potentially much weaker) winds than in wind tunnels, consistent with indirect observational evidence on Earth and Mars. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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14 pages, 2327 KiB

Open AccessArticle

Tree Belts for Decreasing Aeolian Dust-Carried Pesticides from Cultivated Areas

by Eli Zaady, Itzhak Katra, Shimshon Shuker, Yaakov Knoll and Sarig Shlomo

Geosciences 2018, 8(8), 286; https://doi.org/10.3390/geosciences8080286 - 30 Jul 2018

Cited by 13 | Viewed by 3146

Abstract

The aim of this study was to investigate the function of tree belts in reducing the aeolian transport of dust particles carrying pesticides. The study examined the importance of the buffer zones created by commonly planted trees (Eucalyptus camaldulensis, Pinus halepensis (pine) and Ceratonia siliqua (carob)). The methods include analyzing the quantity and the chemical composition of pesticides carried by aeolian dust particles from the intensively cultivated fields and orchards, where pesticides were applied, towards the tree belts nearby. Eighteen different chemicals used as insecticides, fungicides and herbicides, were found both in the agricultural fields and in the adjacent tree belts, suggesting an important function of the trees. This ecological service has rarely been taken into consideration by management policies of tree plantings in farmland areas. To integrate this service into agriculture, especially in the case of agricultural fields and orchards, which are adjacent to populated areas, planting tree belts should be positively considered as a means for reducing aeolian dust and air pollution, mainly in order to reduce leakage of pesticides, which are a cause for significant health concerns. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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16 pages, 3315 KiB

Open AccessArticle

Migration of Barchan Dunes in Qatar–Controls of the Shamal, Teleconnections, Sea-Level Changes and Human Impact

by Max Engel, Fabian Boesl and Helmut Brückner

Geosciences 2018, 8(7), 240; https://doi.org/10.3390/geosciences8070240 - 29 Jun 2018

Cited by 14 | Viewed by 5579

Abstract

Barchan dune fields are a dominant landscape feature in SE Qatar and a key element of the peninsula’s geodiversity. The migration of barchan dunes is mainly controlled by dune size, wind patterns, vegetation cover and human impact. We investigate the variability of dune migration in Qatar over a time period of 50 years using high-resolution satellite and aerial imagery. We then explore its relation to the regional Shamal wind system, teleconnection patterns, and limitations in sand supply associated with the transgression of the Arabian Gulf. Strong size-dependent differences in migration rates of individual dunes as well as significant decadal variability on a dune-field scale are detected, which are found to correlate with the intensity of the North Atlantic Oscillation (NAO) and the Indian Summer Monsoon (ISM), in particular during years of relatively strong (weak) summer Shamals. High uncertainties associated with the extrapolation of migration rates back into the Holocene, however, do not permit further examination of the timing of the loss of sand supply and the onset of the mid-Holocene relative sea-level (RSL) highstand. For the youngest phase considered in this study (2006–2015), human impact has likely accelerated dune migration under a weakening Shamal regime through sand mining and excessive vehicle traffic upwind of the core study area. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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17 pages, 4183 KiB

Open AccessArticle

Migration and Morphology of Asymmetric Barchans in the Central Hexi Corridor of Northwest China

by Zhengcai Zhang, Zhibao Dong, Guangyin Hu and Eric J. R. Parteli

Geosciences 2018, 8(6), 204; https://doi.org/10.3390/geosciences8060204 - 06 Jun 2018

Cited by 23 | Viewed by 6520

Abstract

Crescent-shaped barchan dunes often display an asymmetric shape, with one limb longer than the other. As shown in previous studies, asymmetric bimodal winds constitute one major cause of barchan asymmetry, but the heterogeneous conditions of sand availability or flux, as well as topographic influences, may be also important. Understanding the morphology and dynamics of asymmetric barchans may have an impact in a broad range of areas, particularly as these dunes may serve as a proxy for planetary wind regimes and soil conditions in extraterrestrial environments. However, in addition to the existing theories and numerical models that explain barchan asymmetry, direct measurements of migration rates and morphologic changes of real asymmetric barchans over a time span of several years would be beneficial. Therefore, here we report such measurements, which we have acquired by investigating asymmetric barchans in the Hexi Corridor, northwest of China. We have found that dune interactions and asymmetric influx conditions are the most important causes of barchan asymmetry in this field. Particle size distributions in the Hexi Corridor display strong variations over different parts of the asymmetric barchans, as well as over different dunes, with gravel particles being incorporated from the substrate as the dunes migrate. Our observations have shown that upwind sediment sources are important for dune formation in the Hexi Corridor, and that interdune interactions affect dune shape in different ways, depending on their offset. The asymmetric barchans in the Hexi Corridor are active, with an average migration rate (MR) between 8 and 53 m year⁻¹, in spite of the different asymmetric shapes. Our data for dune migration rates can be described well by a scaling of MR = A/(W + W0), where W is the barchan cross-wind width, A ≈ 2835 m² s⁻¹, and W0 ≈ 44 m. A similar scaling fits very well the migration rate as a function of dune along-wind width L, (i.e., MR = B/(L + L0), with B ≈ 1722 m² s⁻¹ and L0 ≈ 13 m). Linear relations are also found between both dune widths and the average limb and windward side lengths, thus indicating that the morphometric relations that are predicted from models for steady-state, symmetric crescent-shaped dunes can be applied to different transitional morphologies of interacting, asymmetric barchans. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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20 pages, 7582 KiB

Open AccessArticle

Airflow Dynamics over a Beach and Foredune System with Large Woody Debris

by Michael J. Grilliot, Ian J. Walker and Bernard O. Bauer

Geosciences 2018, 8(5), 147; https://doi.org/10.3390/geosciences8050147 - 24 Apr 2018

Cited by 20 | Viewed by 4222

Abstract

Airflow dynamics over beach-foredune systems can be complex. Although a great deal is known about the effects of topographic forcing and vegetation cover on wind-field modification, the role of large woody debris (LWD) as a roughness element and modifier of boundary layer flow is relatively understudied. Individual pieces of LWD are non-porous elements that impose bluff body effects and induce secondary flow circulation that varies with size, density, and arrangement. Large assemblages of LWD are common on beaches near forested watersheds and collectively have a degree of porosity that increases aerodynamic roughness in ways that are not fully understood. A field study on a mesotidal sandy beach with a scarped foredune (Calvert Island, British Columbia, Canada) shows that LWD influences flow patterns and turbulence levels. Overall mean and fluctuating energy decline as flow transitions across LWD, while mean energy is converted to turbulent energy. Such flow alterations have implications for sand transport pathways and resulting sedimentation patterns, primarily by inducing deposition within the LWD matrix. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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29 pages, 25099 KiB

Open AccessArticle

Late Quaternary Soil Development Enhances Aeolian Landform Stability, Moenkopi Plateau, Southern Colorado Plateau, USA

by Amy L. Ellwein, Leslie D. McFadden, Joseph A. McAuliffe and Shannon A. Mahan

Geosciences 2018, 8(5), 146; https://doi.org/10.3390/geosciences8050146 - 24 Apr 2018

Cited by 6 | Viewed by 4940

Abstract

The Moenkopi dune field in northeastern Arizona covers roughly 1250 km², but most of the field is inactive. Dune deposits on the Moenkopi Plateau (MP) have remained inactive throughout the Holocene despite periods of elevated aridity or historical reductions of vegetation cover by livestock grazing. We argue that this inactivity is not because of any diminishment of driving forces in the aeolian system (e.g., insufficient winds), but rather because of increased cohesion due to soil development that enhances resistance to wind erosion. Abundant aeolian sediments were supplied to the Black Mesa region by the Little Colorado River and its tributaries during the late Pleistocene (MIS 2 and 3), which enabled the development of climbing dunes and transport of sand over the Adeii Eechii Cliffs and onto the MP. These deposits (Qe1) stabilized during the Pleistocene/Holocene climatic transition (~12–7.5 ka) because of reduced sediment supply and high dust flux which resulted in rapid soil formation. Erosion of climbing dunes/sand ramps from the Adeii Eechii Cliffs eliminated delivery of large quantities of new sand to the MP during the mid to late Holocene. Soil development within the Qe1 mantle increased sediment cohesion and prevented widespread aeolian reactivation during the Holocene, despite the occurrence of conditions (wind speed, climate, etc.) under which dune reactivation would be expected. Drylands comprise roughly 40% of the land cover of earth and climate models predict their expansion. Pedogenic stability is not commonly considered in climate-based models used to predict aeolian activity. To improve predictions of future dune activity in drylands, the degree of soil development in aeolian deposits should be considered when evaluating sediment availability in aeolian systems. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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12 pages, 611 KiB

Open AccessArticle

Sand Dune Albedo Feedback

by Yosef Ashkenazy and Elad Shilo

Geosciences 2018, 8(3), 82; https://doi.org/10.3390/geosciences8030082 - 27 Feb 2018

Cited by 9 | Viewed by 3823

Abstract

Sand dunes cover substantial parts of desert areas. Fully active dunes are bare, while fixed dunes are stabilized by vegetation and biogenic crust, and the dune activity is affected by the wind. Here we suggest the following atmosphere-sand dune feedback: spatial differences in the dunes’ vegetation and biogenic crust cover lead to differences in albedo as the albedo of bare sand is larger than that of vegetation and biogenic crust. This leads to a higher temperature over the vegetated area, resulting in air flow from the bare dune area to the vegetated dune area, thus increasing the wind activity over the vegetated dune area. In turn, this leads to enhanced stress on the vegetation and enhanced dune activity and thus to a decrease in vegetation. These changes in vegetation cover affect the surface albedo, leading to a change in wind activity. We examined this feedback using an atmospheric general circulation model, Weather Research and Forecasting (WRF), in selected regions of the northwestern Negev Desert and the Sahara/Sahel region, and we show that changes in surface albedo do indeed lead to significantly enhanced wind activity over the lower albedo region. We then incorporated this feedback into a simple vegetated dune model, showing that the multiple states associated with active and fixed dunes can be obtained for a larger range of parameters and that the stables states become more extreme (i.e., the fixed dune state becomes more vegetated and the active dune state becomes less vegetated). Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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Review

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32 pages, 9180 KiB

Open AccessReview

Sand Seas and Dune Fields of Egypt

by Olaf Bubenzer, Nabil S. Embabi and Mahmoud M. Ashour

Geosciences 2020, 10(3), 101; https://doi.org/10.3390/geosciences10030101 - 10 Mar 2020

Cited by 23 | Viewed by 10538

Abstract

The article reviews the state of knowledge about distribution, sizes, dynamics, and ages of all sand seas (N = 6) and dune fields (N = 10) in Egypt (1,001,450 km²). However, chronological data (Optically Stimulated Luminescence, Thermoluminescence), used in the INQUA (International Union for Quaternary Research) dune database, only exists from three of the five sand seas located in the Western Desert of Egypt. The North Sinai Sand Sea and four of the ten dune fields are located near the Nile Valley, the delta or the coast and therefore changed drastically due to land reclamation during the last decades. Here, but also in the oases, their sands pose a risk for settlements and farmland. Our comprehensive investigations of satellite images and our field measurements show that nearly all terrestrial dune forms can be observed in Egypt. Longitudinal dunes and barchans are dominant. Sand seas cover about 23.8% (with an average sand coverage of 74.8%), dune fields about 4.4% (with an average sand coverage of 31.7%) of its territory. For the Great Sand Sea and the Farafra Sand Sea, situated in the central and northern part of the Western Desert, a Late Glacial transformation by strong westerlies was found, but not for the Selima Sand Sea, situated in the south of Egypt. Regarding the sparse chronological data up to now, for a reasonable estimation of future sand mobility in the course of global climate change, further data are essential. Finally, further studies concerning sand mobility, local wind systems, and land use are needed. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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34 pages, 7659 KiB

Open AccessReview

Role of Aeolian Dust in Shaping Landscapes and Soils of Arid and Semi-Arid South Africa

by Joseph R. McAuliffe, Leslie D. McFadden and M. Timm Hoffman

Geosciences 2018, 8(5), 171; https://doi.org/10.3390/geosciences8050171 - 10 May 2018

Cited by 16 | Viewed by 7533

Abstract

The deposition of fine aeolian sediment profoundly influences the morphology of several different landscapes of the arid and semi-arid western portion of South Africa. Such landscapes and features include: (1) regularly-spaced mounds known as heuweltjies of the succulent Karoo region, (2) barren stone pavements in the more arid regions, and (3) hillslopes with smooth, curvilinear slope profiles that are mantled with coarse, stony colluvium. Investigations of each of these are presented, together with comparisons of similar features found within arid and semi-arid portions of Western North America. Recent findings suggest that the formation of the distinct, regularly-spaced heuweltjies involves a linked set of biological and physical processes. These include nutrient accumulation by termites and the production of dense vegetation patches, which, in turn, serve as a trap for aeolian sediments. Dust deposition is also responsible for the formation of stone pavements as demonstrated by research conducted principally in the Mojave Desert region of the United States. Mineralogical and geochronological studies have demonstrated that the stone clasts remain on the surface as fine aeolian sediments are translocated downward beneath the clasts resulting in a silt-rich soil horizon directly beneath the clasts. Pavements examined in South Africa have the same morphological features that can only be explained by the same process. The formation of soils on hillslopes mantled with stony colluvium are commonly viewed as having formed through the in-situ weathering of the stony colluvium. However, like pavements, mantles of coarse, stony colluvium are effective dust traps that provide the long-term stability required for advanced development of thick, fine-grained soils. This process contributes to the evolution of smooth, vegetated, curvilinear slope profiles. In each of these examples, the accumulation of dust has a profound influence, not only in soil formation, but also on the development of dominant landform characteristics. A greater awareness of these processes will contribute considerably to the growth of knowledge about soils and landscape development in the drylands of South Africa. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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19 pages, 913 KiB

Open AccessFeature PaperReview

Transport of Mineral Dust and Its Impact on Climate

by Kerstin Schepanski

Geosciences 2018, 8(5), 151; https://doi.org/10.3390/geosciences8050151 - 26 Apr 2018

Cited by 120 | Viewed by 11409

Abstract

Mineral dust plays a pivotal role in the Earth’s system. Dust modulates the global energy budget directly via its interactions with radiation and indirectly via its influence on cloud and precipitation formation processes. Dust is a micro-nutrient and fertilizer for ecosystems due to its mineralogical composition and thus impacts on the global carbon cycle. Hence, dust aerosol is an essential part of weather and climate. Dust suspended in the air is determined by the atmospheric dust cycle: Dust sources and emission processes define the amount of dust entrained into the atmosphere. Atmospheric mixing and circulation carry plumes of dust to remote places. Ultimately, dust particles are removed from the atmosphere by deposition processes such as gravitational settling and rain wash out. During its residence time, dust interacts with and thus modulates the atmosphere resulting into changes such as in surface temperature, wind, clouds, and precipitation rates. There are still uncertainties regarding individual dust interactions and their relevance. Dust modulates key processes that are inevitably influencing the Earth energy budget. Dust transport allows for these interactions and at the same time, the intermittency of dust transport introduces additional fluctuations into a complex and challenging system. Full article

(This article belongs to the Special Issue Aeolian Processes and Geomorphology)

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