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Large‐scale classical dust cycle models, developed more than two decades ago, assume for simplicity that the Earth's land surface is devoid of vegetation, reduce dust emission estimates using a vegetation cover complement, and calibrate estimates to observed atmospheric dust optical depth (DOD). Consequently, these models are expected to be valid for use with dust‐climate projections in Earth System Models. We reveal little spatial relation between DOD frequency and satellite observed dust emission from point sources (DPS) and a difference of up to 2 orders of magnitude. We compared DPS data to an exemplar traditional dust emission model (TEM) and the albedo‐based dust emission model (AEM) which represents aerodynamic roughness over space and time. Both models overestimated dust emission probability but showed strong spatial relations to DPS, suitable for calibration. Relative to the AEM calibrated to the DPS, the TEM overestimated large dust emission over vast vegetated areas and produced considerable false change in dust emission. It is difficult to avoid the conclusion that calibrating dust cycle models to DOD has hidden for more than two decades, these TEM modeling weaknesses. The AEM overcomes these weaknesses without using masks or vegetation cover data. Considerable potential therefore exists for ESMs driven by prognostic albedo, to reveal new insights of aerosol effects on, and responses to, contemporary and environmental change projections. Plain Language Summary: Mineral dust influences Earth's systems, and understanding its impacts relies on numerical models which include large uncertainties. We compared measurements of dust optical depth (DOD) frequency of occurrence (probability) and satellite observed dust emission frequency from point sources (DPS) across North America. We found up to 2 orders of magnitude difference between DOD probability and DPS probability. Compared with DPS probability, we found an exemplar traditional dust emission model (TEM) and the albedo‐based dust emission model (AEM) both overestimated dust emission probability by up to 1 order of magnitude with statistically significant relations, suitable for calibration. Relative to the AEM calibrated to DPS, the exemplar TEM overestimated large dust emission over vast vegetated areas and produced considerable false change in dust emission. Tuning dust cycle models to DOD has very likely hidden, for more than two decades, these TEM weaknesses with implications for our understanding of Earth's systems. Considerable potential exists for new insights of dust‐climate in Earth System Models by using AEM with prognostic albedo. Key Points: Tuning dust models to dust optical depth (DOD) hides dust emission model weaknesses including overestimates and false change in vegetated areasNew shadow‐shelter model calibrated to observed dust emission circumvents unrealistic model assumptionsTwo orders of magnitude difference between DOD and observed dust emission without significant relation [ABSTRACT FROM AUTHOR]

Determining the controls on aeolian dust emissions from major sources is necessary for reliable quantification of atmospheric aerosol concentrations and fluxes. However, ground‐based measurements of dust emissions at‐source are rare and of generally short duration, failing to capture the annual cycle. Here, we provide new insights into dust dynamics by measuring aerosol concentrations and meteorological conditions for a full year (July 2015–June 2016) at Etosha Pan, Namibia, a globally significant dust source. Surface deployed field instrumentation provided 10‐min averaged data on meteorological conditions, aerosol concentration (mg/m3), and horizontal dust flux (g/m2/min10). A Doppler lidar provided additional data for some of the period. 51 significant dust events were identified in response to strong E‐ENE winds. We demonstrate that these events occurred throughout the year and were not restricted to the austral winter, as previously indicated by satellite observations. Peak horizontal flux occurred in the spring (November) due to strengthening erosive winds and highly desiccating conditions increasing surface erodibility. We identify a strong seasonal differentiation in the meteorological mechanisms controlling dust uplift; low‐level jets on dry winter mornings (61% of all events), and cold pool outflows in humid summer evenings (39% of events). Significantly, we demonstrate a very strong bias toward the contribution of low frequency and high magnitude events, with nearly 31% of annual horizontal dust flux generated by only 6 individual events. Our study demonstrates how longer‐term (≈1 year), ground‐based, and at‐source field measurements can radically improve interpretations of dust event dynamics and controls at major source locations. Plain Language Summary: Atmospheric dust is important because it affects climate, human health, and nutrient distribution. Most atmospheric dust is sourced from dry lake beds in deserts and much of our understanding of dust emission comes from satellite observations. Few field studies have measured dust emission from such sources for more than a few months and so our understanding of the processes that govern dust emission is partial. We measured dust concentrations and associated meteorological conditions for a full year at Etosha Pan in Namibia, a major source of dust globally. We found that dust emission occurred throughout the year, not just in winter as had previously been thought. Our data showed that the meteorological mechanisms controlling dust emission changed seasonally. In dry winter mornings dust was eroded by jets of fast‐moving winds soon after sunrise. In summer, emission occurred in the late evenings due to high‐speed winds associated with the development of convective storms. Further, dust emission was dominated by high magnitude and low frequency events. Our field data demonstrate the seasonal complexity in the controlling mechanisms of dust emission which need to be accounted for in calculations of atmospheric dust loading. Key Points: Ground‐based data show aeolian dust emissions occur throughout the year, not restricted to winter as indicated by satellite observationsEmissions are largely driven by low‐level jets in the dry winter, and by cold pool outflows in the more humid summerThe magnitude of emissions is dominated by only a few events, with six events accounting for nearly 31% of all horizontal dust flux [ABSTRACT FROM AUTHOR]

The contribution of mineral dust from high-latitude sources has remained an under-examined feature of the global dust cycle. Dust events originating at high latitudes can provide inputs of aeolian sediment to regions lying well outside the subtropical dust belt. Constraining the seasonal variability and preferential pathways of dust from high-latitude sources is important for understanding the potential impacts that the dust may have on wider environmental systems, such as nearby marine or cryospheric domains. This study quantifies dust pathways from two areas exhibiting different emission dynamics in the north and south of Iceland, which is a prominent Northern Hemisphere dust source. The analysis uses air parcel trajectory modelling, and for the first time for high-latitude sources, explicitly links all trajectory simulations to time-specific (meteorological) observations of suspended dust. This approach maximises the potential for trajectories to represent dust, and illustrates that trajectory climatologies not limited to dust can grossly overestimate the potential for dust transport. Preferential pathways emerge that demonstrate the role of Iceland in supplying dust to the Northern Atlantic and sub-Arctic oceans. For dust emitted from northern sources, a dominant route exists to the northeast, into the Norwegian, Greenland and Barents Seas, although there is also potential for delivery to the North Atlantic in summer months. From the southern sources, the primary pathway extends into the North Atlantic, with a high density of trajectories extending as far south as 50°N, particularly in spring and summer. Common to both southern and northern sources is a pathway to the west-southwest of Iceland into the Denmark Strait and towards Greenland. For trajectories simulated at ≤500 m, the vertical development of dust plumes from Iceland is limited, likely due to the stable air masses of the region suppressing the potential for vertical motion. Trajectories rarely ascend high enough to reach the central portions of the Greenland Ice Sheet. The overall distribution of trajectories suggests that contributions of Icelandic dust are relatively more important for neighbouring marine environments than the cryosphere. [ABSTRACT FROM AUTHOR]

Dust sources have been revealed through remote sensing, first regionally by ~1° resolution sensors (TOMS), then at sub-basin scale by moderate-resolution sensors (MODIS). Sensors with higher spatial resolution until recently were poorly temporally-resolved, precluding their use for systematic investigations of sources. Now, "CubeSat" constellations with high-temporal-and-spatial-resolution sensors such as PlanetScope offer ~3 m resolution and daily (to sub-daily) temporal resolution. We illustrate the spatio-temporal dust plume observation capabilities of CubeSat data through a dust event case study, Bolson de los Muertos playa, Chihuahuan Desert, Mexico. For the event, PlanetScope showed numerous discrete point sources, revealing variability of surface erodibility and emission over ~8% of a focus area at time of capture. The unprecedented detail of PlanetScope imagery revealed plume development where outer-playa sands and fluvial-deltaic inputs contact lacustrine silts/clays, consistent with field-studies. PlanetScope's high fidelity improves spatial quantification and temporal constraint of source activity, and we assess the spatio-temporal capabilities of CubeSat in context with other dust observation remote sensing systems. Compared to previous satellite technologies, CubeSats bring better potential to link remote sensing to field observations of emission. This leap forward in the remote sensing of dust sources calls for the systematic analysis of CubeSat imagery in source areas. Image 1 • Remote sensing has enabled key characterisations of mineral dust sources globally. • Moderate-resolution sensors cannot be reconciled with field study of dust emission. • New CubeSat technology allows observation of active emission processes. • Potential for sub-daily source monitoring from sensors in constellations. • We call for the systematic application of CubeSat imagery over dust sources. [ABSTRACT FROM AUTHOR]