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Abstract. Mineral dust is the most abundant aerosol species by massin the atmosphere, and it impacts global climate, biogeochemistry, and humanhealth. Understanding these varied impacts on the Earth system requiresaccurate knowledge of dust abundance, size, and optical properties, and howthey vary in space and time. However, current global models show substantialbiases against measurements of these dust properties. For instance, recentstudies suggest that atmospheric dust is substantially coarser and moreaspherical than accounted for in models, leading to persistent biases inmodelled impacts of dust on the Earth system. Here, we facilitate moreaccurate constraints on dust impacts by developing a new dataset: DustConstraints from joint Observational-Modelling-experiMental analysis(DustCOMM). This dataset combines an ensemble of global model simulationswith observational and experimental constraints on dust size distributionand shape to obtain more accurate constraints on three-dimensional (3-D)atmospheric dust properties than is possible from global model simulationsalone. Specifically, we present annual and seasonal climatologies of the 3-Ddust size distribution, 3-D dust mass extinction efficiency at 550 nm, andtwo-dimensional (2-D) atmospheric dust loading. Comparisons with independentmeasurements taken over several locations, heights, and seasons show thatDustCOMM estimates consistently outperform conventional global modelsimulations. In particular, DustCOMM achieves a substantial reduction in thebias relative to measured dust size distributions in the 0.5–20 µmdiameter range. Furthermore, DustCOMM reproduces measurements of dust massextinction efficiency to almost within the experimental uncertainties,whereas global models generally overestimate the mass extinction efficiency.DustCOMM thus provides more accurate constraints on 3-D dust properties, andas such can be used to improve global models or serve as an alternative toglobal model simulations in constraining dust impacts on the Earth system.
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Climate models miss most of the coarse dust in the atmosphere
Coarse mineral dust (diameter, ≥5 μm) is an important component of the Earth system that affects clouds, ocean ecosystems, and climate. Despite their significance, climate models consistently underestimate the amount of coarse dust in the atmosphere when compared to measurements. Here, we estimate the global load of coarse dust using a framework that leverages dozens of measurements of atmospheric dust size distributions. We find that the atmosphere contains 17 Tg of coarse dust, which is four times more than current climate models simulate. Our findings indicate that models deposit coarse dust out of the atmosphere too quickly. Accounting for this missing coarse dust adds a warming effect of 0.15 W·m −2 and increases the likelihood that dust net warms the climate system. We conclude that to properly represent the impact of dust on the Earth system, climate models must include an accurate treatment of coarse dust in the atmosphere.
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- Award ID(s):
- 1856389
- PAR ID:
- 10166141
- Date Published:
- Journal Name:
- Science Advances
- Volume:
- 6
- Issue:
- 15
- ISSN:
- 2375-2548
- Page Range / eLocation ID:
- eaaz9507
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1126/sciadv.aaz9507
