气候变化领域集成服务门户(CCPortal): Apparent dust size discrepancy in aerosol reanalysis in north African dust after long-range transport

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DOI	10.5194/acp-20-10047-2020
	Apparent dust size discrepancy in aerosol reanalysis in north African dust after long-range transport
	Kramer S.J.; Alvarez C.; Barkley A.E.; Colarco P.R.; Custals L.; Delgadillo R.; Gaston C.J.; Govindaraju R.; Zuidema P.
发表日期	2020
ISSN	1680-7316
起始页码	10047
结束页码	10062
卷号	20 期号:16
英文摘要	North African dust reaches the southeastern United States every summer. Size-resolved dust mass measurements taken in Miami, Florida, indicate that more than one-half of the surface dust mass concentrations reside in particles with geometric diameters less than 2.1 ?m, while vertical profiles of micropulse lidar depolarization ratios show dust reaching above 4 km during pronounced events. These observations are compared to the representation of dust in the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) aerosol reanalysis and closely related Goddard Earth Observing System model version 5 (GEOS-5) Forward Processing (FP) aerosol product, both of which assimilate satellite-derived aerosol optical depths using a similar protocol and inputs. These capture the day-to-day variability in aerosol optical depth well, in a comparison to an independent sun-photometer-derived aerosol optical depth dataset. Most of the modeled dust mass resides in diameters between 2 and 6 ?m, in contrast to the measurements. Model-specified mass extinction efficiencies equate light extinction with approximately 3 times as much aerosol mass, in this size range, compared to the measured dust sizes. GEOS-5 FP surface-layer sea salt mass concentrations greatly exceed observed values, despite realistic winds and relative humidities. In combination, these observations help explain why, despite realistic total aerosol optical depths, (1) free-tropospheric model volume extinction coefficients are lower than those retrieved from the micro-pulse lidar, suggesting too-low model dust loadings in the free troposphere, and (2) model dust mass concentrations near the surface can be higher than those measured. The modeled vertical distribution of dust, when captured, is reasonable. Large, aspherical particles exceeding the modeled dust sizes are also occasionally present, but dust particles with diameters exceeding 10 ?m contribute little to the measured total dust mass concentrations after such long-range transport. Remaining uncertainties warrant a further integrated assessment to confirm this study s interpretations. © 2020 Laser Institute of America. All rights reserved.
语种	英语
scopus关键词	aerosol composition; aerosol formation; concentration (composition); dust; optical depth; pollutant transport; size distribution; troposphere; United States
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/141132
作者单位	Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, United States; Nasa Goddard Space Flight Center, Greenbelt, MD, United States
推荐引用方式 GB/T 7714	Kramer S.J.,Alvarez C.,Barkley A.E.,et al. Apparent dust size discrepancy in aerosol reanalysis in north African dust after long-range transport[J],2020,20(16).
APA	Kramer S.J..,Alvarez C..,Barkley A.E..,Colarco P.R..,Custals L..,...&Zuidema P..(2020).Apparent dust size discrepancy in aerosol reanalysis in north African dust after long-range transport.Atmospheric Chemistry and Physics,20(16).
MLA	Kramer S.J.,et al."Apparent dust size discrepancy in aerosol reanalysis in north African dust after long-range transport".Atmospheric Chemistry and Physics 20.16(2020).