DOI: 10.1029/2012JD018201
论文题名: A global analysis on the view-angle dependence of plane-parallel oceanic liquid water cloud optical thickness using data synergy from MISR and MODIS
作者: Liang L. ; Girolamo L.D.
刊名: Journal of Geophysical Research Atmospheres
ISSN: 21698996
出版年: 2013
卷: 118, 期: 5 起始页码: 2389
结束页码: 2403
语种: 英语
英文关键词: cloud optical thickness
; plane-parallel cloud
; remote sensing
; retrieval bias
Scopus关键词: Backscattering
; Remote sensing
; Satellite imagery
; Cloud optical thickness
; Liquid water clouds
; Moderate resolution imaging spectroradiometer
; Multiangle imaging spectroradiometer
; Relative azimuth angle
; retrieval bias
; Scene identifications
; Spatial heterogeneity
; Radiometers
; backscatter
; cloud radiative forcing
; data set
; heterogeneity
; MISR
; MODIS
; optical depth
; remote sensing
; view
; zenith angle
英文摘要: We examine the viewing zenith angle dependent bias (VZA bias) in warm cloud optical thickness (τ) retrieved from a plane-parallel approach applied to fused Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR) data for the months of January and July between 2001 and 2008. The near-simultaneous multiple view-angle observations from MISR offers many advantages over previous τ-VZA bias studies: 1) The analysis no longer requires seasonal and latitudinal cloud invariant assumptions, 2) consistent cloudy scene identification with VZA, 3) stratification of VZA-bias with scene characteristics, and 4) a greater range of sun-view geometries. Contrasting results between previous studies are resolved through careful consideration of the relative azimuth angle (RAZ) between sun and view. Relative to nadir-retrieved τ, τ increases in both forward- and backscatter directions with higher value in backscatter directions for solar zenith angle (SZA) < ~40°. For SZA ~40°, τ increases with increasing VZA in backscatter directions and strongly decreases in forward-scatter directions. For the most oblique views, ~40-100% absolute monthly mean differences relative to nadir-retrieved τ is common. This behavior is strongly tied to the sampled RAZ and explained based on three factors tied to the spatial heterogeneity of clouds. These factors also explain the behavior of the τ-VZA bias when stratified by nadir-retrieved τ and spatial heterogeneity, even in the thin-cloud limit where sun-glint effects are evident. We also observe an underestimation of τ relative to nadir in the rainbow-scattering directions and attribute it to an overestimation of the cloud-drop effective radius retrieved from MODIS due to cloud heterogeneity. There remains a need to quantify the bias in nadir-retrieved τ as a function of SZA and spatial heterogeneity as a step toward providing bias correction over a wide range of sun-view geometries. © 2012. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/63867
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign, Urbana IL, United States; Science Systems and Applications, Inc., 1 Enterprise Parkway, Hampton, VA 23666, United States
Recommended Citation:
Liang L.,Girolamo L.D.. A global analysis on the view-angle dependence of plane-parallel oceanic liquid water cloud optical thickness using data synergy from MISR and MODIS[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(5)