DOI: 10.1002/grl.50603
论文题名: Shape-induced gravitational sorting of Saharan dust during transatlantic voyage: Evidence from CALIOP lidar depolarization measurements
作者: Yang W. ; Marshak A. ; Kostinski A.B. ; Várnai T.
刊名: Geophysical Research Letters
ISSN: 0094-8842
EISSN: 1944-8573
出版年: 2013
卷: 40, 期: 12 起始页码: 3281
结束页码: 3286
语种: 英语
英文关键词: CALIPSO
; depolarization
; particle shape
; remote sensing
; Saharan dust
; transport
Scopus关键词: CALIPSO
; Cloud-aerosol lidar with orthogonal polarizations
; Differential settling
; Light depolarization
; Particle shape
; Saharan dust
; transport
; Vertical stratification
; Depolarization
; Optical radar
; Remote sensing
; Screening
; Sorting
; Dust
; altitude
; CALIPSO
; data set
; dust
; gravity flow
; light scattering
; mixing
; radiative transfer
; remote sensing
; satellite data
; spatiotemporal analysis
; Sahara
英文摘要: Motivated by the physical picture of shape-dependent air resistance and, consequently, shape-induced differential sedimentation of dust particles, we searched for and found evidence of dust particle asphericity affecting the evolution and distribution of dust-scattered light depolarization ratio (δ). Specifically, we examined a large data set of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations of Saharan dust from June to August 2007. Observing along a typical transatlantic dust track, we find that (1) median δ is uniformly distributed between 2 and 5 km altitudes as the elevated dust leaves the west coast of Africa, thereby indicating uniformly random mixing of particle shapes with height; (2) vertical homogeneity of median δ breaks down during the westward transport: between 2 and 5 km δ increases with altitude and this increase becomes more pronounced with westward progress; (3) δ tends to increase at higher altitude (>4 km) and decrease at lower altitude (<4 km) during the westward transport. All these features are captured qualitatively by a minimal model (two shapes only), suggesting that shape-induced differential settling and consequent sorting indeed contribute significantly to the observed temporal evolution and vertical stratification of dust properties. By implicating particle shape as a likely cause of gravitational sorting, these results will affect the estimates of radiative transfer through Saharan dust layers. Key Points Saharan dust over the Atlantic is studied using lidar data of CALIPSO satellite Data show that particle shape impacts dust fall speed and vertical structure Simple shape-dependent settling model reproduces basic features of observations ©2013. American Geophysical Union. All Rights Reserved. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880563786&doi=10.1002%2fgrl.50603&partnerID=40&md5=5f237629f188d2d69f1f2d7f8eb34429
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/6106
Appears in Collections: 气候减缓与适应
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作者单位: Goddard Earth Sciences Technology and Research, Universities Space Research Association, Columbia, MD 21044, United States
Recommended Citation:
Yang W.,Marshak A.,Kostinski A.B.,et al. Shape-induced gravitational sorting of Saharan dust during transatlantic voyage: Evidence from CALIOP lidar depolarization measurements[J]. Geophysical Research Letters,2013-01-01,40(12).