2025 ISAR Virtuaeolian Seminar Series
Chloe Daudon
Inferring wind speed from ripple and dune migration on Earth and Mars
Dunes and ripples are markers of eolian activity. Dunes arise and evolve from the action of wind blowing on sand grains and can thus provide information on past and current wind regime. They constantly adjust and adapt their shape through feedback between the bed topography and the near-surface air flow. This interaction modulates erosion of the stoss side and deposition on the lee side, and eventually results in the dune migration. Here, we present a workflow that quantitatively relates the rate of barchan dunes migration, which can be measured from remote sensing, to the wind velocity, either measured at a meteorological station or extracted from reanalysis data. We validate this workflow using data from Earth and apply it on Mars.
The workflow requires the selection of a sand transport law and the use of computational fluid dynamic (CFD) modeling. This modeling is used to estimate the effect of the local topography on the near surface airflow, namely the speed-up effect. We compare the dune migration rate predicted through the workflow to remote sensing observations, at two barchan dune fields located along the southern rim of the Arabia Gulf. After validating this workflow on Earth, we apply it to a barchan dune field on Mars. The dune migration is used to derive a wind speed distribution, averaged over one Martian year. Finally, we use ripple migration, which is much faster than dune migration, to derive the sub-annual variation of the wind speed.
Date and time: July 22, 2025 at 9:00:00 am PDT
Zoom Registration: https://vu-live.zoom.us/meeting/register/OK1k0B-BTim4jxdhWI_5Qw
PREVIOUS SEMINARS
Yaping Shao
ISAR Career Award 2025. Dust Emission Modelling with Consideration of Source Limitation
To estimate dust emission is a core task of aeolian parameterization schemes. Over the past decades, many dust emission schemes have been proposed. Here, I give an overview of the scheme development. One of the problems yet to solve is to better model source-limited dust emission. I will present a new model which accounts for the evolution of the supply of soil dust depleted by dust emission and enriched by surface renewal. The impact of source limitation to dust emission can be profound and the process of dust emission is more complex and variable than previously considered.
Date and time: June 23, 2025 at 7:00:00 pm CEST
Colin Marvin
Zircon microtextures: A record of Earth’s earliest surface environments
Sedimentary rocks record surface environments throughout Earth’s history. However, alteration by diagenesis, weathering, and metamorphism often obscures the clues used to decipher that archive. Thus, older rocks become more challenging to interpret, leaving cryptic information about Earth’s earliest surface environments. Here, we show that detrital zircon grains preserve an unaltered record of paleo-transport history over billions of years. We systematically document microscopic features on zircon sand grains (‘microtextures’) from 3 modern, continental environments – aeolian, fluvial, and beach shore zone – revealing that microtextures can be used to diagnose transport environment. We validate this approach using an independent set of zircon grains from modern deposits to Paleoarchean rocks with independently known transport histories. Detrital zircons constitute an untapped account of our planet’s earliest surface environments, expanding the applicability of sand microtextural analyses to the first 90% of Earth’s history.
May 29, 2025 at 4:00:00 pm PDT
Nathan Brown
Quantifying ventifact erosion in the desert of southern California
Aeolian abrasion is an important erosional process in arid regions, but abrasion rates on crystalline bedrock are not well quantified beyond instrumental timescales. This is partly because few measurements can reconstruct this erosional history. Recent developments in optically stimulated luminescence (OSL) and cosmogenic radionuclide measurements (CRN), however, offer two independent and complementary methods for determining hard rock erosion rates on timescales of decades to millennia. In this study, our team has collected rock samples from across the surfaces of ten boulder-sized ventifacts, located at two field sites in the deserts of southern California: Silver Lake, north of Baker, and Garnet Hill, north of Palm Springs. OSL samples, which are sensitive to centimeter-scale erosion, were collected inside and outside of erosional features (e.g., flutes, scallops) and along the broad surfaces of abrading and nonabrading boulder faces. CRN samples, which are sensitive to decimeter-scale erosion, were collected from the abrading faces. We have also estimated modern rock hardness values across these ventifacts and used stereophotogrammetry to develop 3-D models of rock morphology. Initial results are consistent with the hypothesis that ventifact erosion rates in southern California peaked in the early Holocene and have decreased substantially until present. Finally, I discuss the promise and limitations of this new way of understanding ventifact erosion.
2024 ISAR Virtuaeolian Seminar Series
Laurie Barrier
Title: Studying aeolian landscapes and fluxes from source to sink
Abstract: Over the past two decades, source-to-sink studies have yielded extensive insights into the spatio-temporal dynamics of fluvial-dominated landscapes and their response to tectonic, climatic, and biologic forcings. These studies document sediment pathways from upstream production (source) to downstream accumulation (sink) areas, aiming to assess the impact of transport processes on the morphological and stratigraphical evolutions of landscapes and sedimentary basins. This approach has also been applied to a variety of morpho-sedimentary systems in continental, lacustrine and submarine environments, not only on Earth but also on other planetary bodies. However, the contribution of aeolian processes in shaping continental surfaces and controlling their mass exchanges with oceans and the atmosphere is still subject to considerable uncertainties. Unlike sediment transport by rivers, for example, this is likely due to the fact that wind-driven transport is not associated with well-identified channel networks that directly link sand and dust sources and sinks flowing down the topography. Consequently, the potential of source-to-sink methodologies has yet to be fully explored and utilized for the qualitative and quantitative analysis of aeolian systems and their coupling with the atmosphere and hydrosphere. In this presentation, I will begin by reviewing the general concepts and traditional methods of the source-to-sink approach. Then, we will examine the specificities of aeolian transport regarding this approach, before considering some applications of its concepts and tools to the particular case of aeolian systems. Finally, we will discuss the new opportunities that can be leveraged in this framework to provide fundamental constraints on aeolian sediment routing systems, landforms and landscapes.
Date and Time: January 21st 10AM CET
Kebonye Dintwe
Title: Assessment of Fire-Induced Albedo Change and Vegetation Recovery Post-Fires in Sub-Saharan Africa Savannas
Abstract: For millions of years, fires have been an integral part of the Earth’s biogeochemical processes and influenced land-atmosphere interactions. At local scale, fires play a critical role in influencing natural selection and plant evolution, a process that contributed to evolution and expansion of flammable ecosystems. Conversely, fire spread is facilitated by plant species that have evolved to withstand burning. In this study, we assessed fire regime in sub-Sharan Africa (SSA) over a 20 years period. We used Moderate Resolution Imaging Spectroradiometer (MODIS) data in our analysis, covering different the following vegetation classes: savannas, grassland, shrubland and cropland. Our analysis indicated that savannas contributed 87.7% of total burn area in south hemisphere Africa (SHA), and 85.2% in north sub-Saharan Africa (NSSA). Grasslands contributed 5.8% and 5.6% of the total burn area in SHA and NSSA, respectively. The contribution of shrubland was fourfold higher in SHA than in NSSA, while the contribution of cropland was 2-fold higher in NSSA than in SHA. Our analysis further indicated that at continental scale, savanna fires play a significant role, as they accounted for 9.9% of the total land surface, followed by grasslands and croplands, each accounting for 0.5% of the total land surface of the continent. These results provide insights on the importance of land use land change dynamics with respect to continental fire regime. Conversion of tropical rainforest into open woodland and savannas could results in increased number of fires and burn surface area. Since fires consume large quantities of biomass and release CO2 and smoke (black carbon) into the atmosphere, the processes of land cover change might trigger positive feedback mechanisms that could exacerbate the impacts of climate change in sub-Saharan Africa
Date & Time: TBD
Marine Poizat
Title: Snow dunes in Antarctica
Abstract: Antarctica is one of the windiest regions on Earth, which result in shaping a variety of snow bedforms, akin to those observed in subtropical sand deserts. However, unlike the well-studied sand dunes, snow dunes have been only described qualitatively, leaving significant gaps in our understanding of their spatial distribution, orientation, and dynamics. Therefore, fundamental questions about the eolian transport of a cohesive material remain unanswered. In this talk, I will explore two snow bedforms in Antarctica: snow barchans and linear snow dunes. First, I will discuss the dynamics and morphology of snow barchans, and correlate it with in-situ weather data. Next, I will present a continent-wide mapping of linear snow dune orientations, demonstrating that on scales ranging from 30 meters to several kilometers, longitudinal dunes are the predominant landform in Antarctica. The predominance of the elongating mode indicates a low availability of mobile snow particles. Our findings emphasize the critical role of snow sintering and cohesion in shaping these distinctive bedforms.
November 20th 5PM CET
Christy Swann
Title: ‘Decoding Windblown Sand: the Life, Science and Legacy of R.A. Bagnold’
Abstract: Aeolian transport on Earth, Mars, and other planetary bodies is a complex process that is difficult to observe in the field and challenging to predict with models. Despite significant advancements in instrumentation and computational techniques, the foundational theories developed by R.A. Bagnold in the 1930s remain highly influential. This presentation will examine the contributions of Bagnold, who initiated his pioneering research on windblown sand during Royal Navy operations in the Libyan desert. Lacking an established community of aeolian researchers, Bagnold collaborated with fluvial sedimentologists to develop methods for measuring and modeling sand transport by wind. He constructed the first wind tunnel for the experimental study of aeolian processes, enabling him to quantitatively and qualitatively assess key phenomena, including modes of sand transport, velocity profiles, thresholds of motion, and the dynamics of particle impact and ejection. Bagnold’s work successfully scaled these small-scale processes to broader understandings of sand transport, dust lifting, and dune formation. By the end of his career, his research extended to marine sediment transport, fluvial dynamics, and aeolian processes on Mars, influencing the study of wind-driven sediment transport across multiple disciplines. This talk will explore Bagnold’s fundamental observations, the assumptions underlying his models, and the enduring impact of his work on contemporary sediment transport research.
Cheryl McKenna Neuman (Trent University) &
Jo Nield (University of Southampton)
Title: Intersection of Field and Lab Measurement. Where’s it at?
Abstract: Measurements of aeolian transport processes are fundamental for model development, parameterization and calibration, which help to inform decision makers. Major advances in measurement techniques in both lab and fieldwork have certainly been driven by new technological advancements, but it can also be argued that limitations in our measurement capabilities continue to constrain what we can learn. At the particle scale, we are often working near the limits of detection, while in both the field and lab, characterizing temporal-spatial variation remains a considerable challenge. However, issues concerning measurement extend well beyond the performance and capabilities of an instrument. The information obtained is strongly dependent on how we use a given tool, as well as the experimental design, and is conditioned and constrained by differences in scaling and even our conceptual constructs. As for example, the classification boundaries between a reptating and saltating grain, or one affected intermittent suspension, are usually indistinct for physical measurements. This webinar will address these issues in the context of experiments carried out in both wind tunnels and the field using high temporal and spatial imaging technologies (e.g. PTV, LDA, TLS) and examine pathways toward the intersection of these remote approaches to better understand aeolian systems and transport dynamics as a whole.
June 17th, 2024 at 10:00 am (EST New York)
Dr. Xiaoping Yang (School of Earth Sciences, Zhejiang University, Hangzhou 310058)
Title: Paleoclimates studied by aeolian deposits
Abstract: Not only aeolian loess but also aeolian sand deposits have been widely utilized as key research objectives for reconstructing palaeoclimatic histories on Earth for a long time. In this presentation I would like to start by sharing my reflections of the exciting new results presented at the ICAR 2023 in Las Cruces in the session ‘Palaeoenvironments’. The talks of that session were focused mainly on study sites located in the USA, subantarctic islands, northern Africa, the Arabic Peninsula, the Europe and China, collectively providing a kind of global vision about current palaeoenvironmental research in drylands. And then I am going to talk about the likelihood and uncertainties in understanding ‘true’ accumulation rates in dated sections of aeolian sands. Aeolian sand sections are essential for understanding wind strength changes in drylands, but the deserts in western China have experienced probably a much more complex histories due to hydrological impacts from surrounding mountain ranges. Thus, a clear separation between aridity and wind strength remains often inconclusive in the areas of Chinese deserts and possibly in other parts of the world also. In addition, the fluvial and lacustrine sedimentary facies interbedded in the aeolian sections are more likely to be indications of the increase in wetness, providing vital evidence for testing reliabilities of palaeoclimatic simulation models which in turn help explain mechanisms of palaeoclimatic changes interpreted from geological evidence. In the current era of big data, studies based on classic theories and methods appears even more important than ever for a correct interpretation of palaeoclimates from the data deciphered from the potential landscape changes histories, as the cases studies in Chinese deserts indicate.
April 15 2024, at 3:00 PM Hangzhou/Beijing Time
Dr. Nicholas Webb (USDA)
Title: Known knowns and known unknowns about vegetation interactions with aeolian
processes: insights from rangeland applications
Aeolian processes and vegetation interact in many ways at different spatial and temporal scales. This presentation will posit that current understanding and models of the interactions have been somewhat limited by the focal areas of our investigations. Looking to ‘new’ applications of aeolian research forces us to critically evaluate what we know, and what we know we don’t know, about aeolian sediment transport vegetation interactions and to identify research gaps and opportunities to address them. I will draw on examples from research on rangeland wind erosion to highlight some gaps and opportunities for field studies and modelling, and for our work to have increased relevance to land management
This seminar is scheduled for Wednesday, March 27th at 9:00 MDT (3 PM UTC) (Time zone converter HERE)
ICAR XI Conference Field Trip Introduction
The White Sands and Jornada Field Trip at ICAR XI
Abstract: ICAR XI will take place in Las Cruces, New Mexico, USA, in a region with a rich history in wind-blown science. As part of the conference we will visit White Sands National Park and The Jornada Experimental Range, which have anchored studies in dunes, rangeland aeolian ecogeomorphology, dust, and more.
In this virtual aeolian seminar, conveners of ICAR will present short talks on aeolian science in the region including geomorphic and anthropogenic history at White Sands, experimental aeolian science in rangelands, and dust production in the SW USA. Presenters include Ryan C. Ewing (Texas A&M), Brandon Edwards (NMSU), and Scott Van Pelt (USDA).
Date : February 22nd at 13:00 CST (UTC-6)
Patrick Hesp
Review, and Evidence for Coastal Transgressive Dunefield (sand sea) Initiation and Evolution
June 2022.
Susana Costas
Exploring coastal dune adaptation through a simplified process-based morphodynamic model
July 2022.
Cheryl McKenna-Neuman
The case for wind tunnel simulation in aeolian research in 2022
August 2022.
Jie Zhang
Wind-tunnel studies of the impact of turbulence on aeolian particle entrainment
September 2022.
Professor Greg Okin
Title: The EMIT (Earth surface MIneral dust source invesTigation) mission: imaging spectroscopy in support of atmospheric dust and climate research
Abstract: Launched July 2022, the purpose of the EMIT (Earth surface MIneral dust source invesTigation) mission is to better constrain the effect of mineral dust on atmospheric radiative forcing. It will accomplish this by mapping common minerals in dust source regions using an imaging spectrometer aboard the International Space Station. With ~7-nm spectral sampling across the reflected solar spectrum (380 – 2500 nm), EMIT spectra contain information about mineral composition, including ferric iron and clay minerals. This talk will describe EMIT, review the principles of mineral identification through spectroscopy, and discuss the application of these results for global radiative transfer modeling to better understand dust’s role in the Earth’s climate system
Date : November 9, 2022 at 12:00pm CEST (UTC-8)
Dr. Martina Klose
Title: Modeling dust emission: insights and challenges
Abstract: By nature, dust models cannot predict dust emission perfectly, because they cannot resemble the land-surface, or the atmosphere, in all detail. However, in comparison with observations, differences obtained from model experiments can provide insights into aspects of modeled dust emission which are more or less uncertain. Here I will present results from using a dust modeling “laboratory”
Date : December 2 2021 at 11:00am CEST (UTC+2)
Professor Kerstin Schepanski
Title: Combining satellite observations, field experiments and model simulation to investigate the atmospheric dust cycle
Abstract: Mineral dust aerosol is a major contributor to the atmospheric aerosol burden. Knowledge on the life-cycle of atmospheric dust is crucial for understanding various aerosol-atmosphere interactions including these on the Earth’s radiation budget, cloud and precipitation formation processes, and bio-productivity ultimately modulating the carbon cycle and human wellbeing. The presentation will discuss results from research that makes complementary use of satellite data, field experiments and numerical modelling in order to improve our understanding of the atmospheric dust cycle, which is inevitable for assessing the climate system and its variability.
Date : October 22, 2021 at 11:00am CEST (UTC+2)
Marcio DaSilva, PhD student, Flinders University
Title: Post-fire dunefield changes and vegetation dynamics on Kangaroo Island, Australia
&
Duc Nguyen, PhD student, University of Otago
Title : Wind flow and sand transport though excavated foredune notches, New Zealand
Date : 16th September, 2021 at 10:30am BST (UTC+1)
Maike Nowatzki, PhD student, Oxford University
Title: Fantastic Dunes and How to Map Them
&
Ismael Kangueehi, PhD student, University of Stellenbosch
Title : Fractional solubility of trace metals in dust from one of the dustiest non-playa environment in the Namib Desert
Date : 16th September, 2021 at 10:30am BST (UTC+1)
Professor Zhiwei Xu
Title: Dune Bistability and Critical Transitions in Chinese Dunes during the Past Twelve Thousand Years.
Date : 9th June, 2021, at 4pm CST (UTC+8).
Professor Bruno Andreotti
Title: Open problems raised by aeolian sediment transport
Date : 26th May, 2021, at 11am local time (UTC+2).
Dr. Cécile Guieu, Senior Scientist
Title : Dust deposition and impacts in the Mediterranean Sea: results from the PEACET|IME oceanographic campaign
Date: 17th March, 2021
Andrew Gunn, PhD Candidate
Title : Mesoscale coupling between aeolian flow and form
Date: 19th January, 2021
Professor Doug Sherman
Deconstructing q: The Empirical Barriers
12th November, 2020