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DOI | 10.5194/acp-17-8489-2017 |
Scale dependence of cirrus horizontal heterogeneity effects on TOA measurements - Part I: MODIS brightness temperatures in the thermal infrared | |
Fauchez, Thomas1,2; Platnick, Steven2; Meyer, Kerry2,3; Cornet, Celine4; Szczap, Frederic5; Varnai, Tamas2,6 | |
2017-07-13 | |
发表期刊 | ATMOSPHERIC CHEMISTRY AND PHYSICS |
ISSN | 1680-7316 |
EISSN | 1680-7324 |
出版年 | 2017 |
卷号 | 17期号:13 |
文章类型 | Article |
语种 | 英语 |
国家 | USA; France |
英文摘要 | This paper presents a study on the impact of cirrus cloud heterogeneities on MODIS simulated thermal infrared (TIR) brightness temperatures (BTs) at the top of the atmosphere (TOA) as a function of spatial resolution from 50m to 10 km. A realistic 3-D cirrus field is generated by the 3DCLOUD model (average optical thickness of 1.4, cloudtop and base altitudes at 10 and 12 km, respectively, consisting of aggregate column crystals of D-eff = 20 mu m), and 3-D thermal infrared radiative transfer (RT) is simulated with the 3DMCPOL code. According to previous studies, differences between 3-D BT computed from a heterogenous pixel and 1-D RT computed from a homogeneous pixel are considered dependent at nadir on two effects: (i) the optical thickness horizontal heterogeneity leading to the plane-parallel homogeneous bias (PPHB) and the (ii) horizontal radiative transport (HRT) leading to the independent pixel approximation error (IPAE). A single but realistic cirrus case is simulated and, as expected, the PPHB mainly impacts the low-spatial-resolution results (above similar to 250 m) with averaged values of up to 5-7 K, while the IPAE mainly impacts the high-spatial-resolution results (below similar to 250 m) with average values of up to 1-2 K. A sensitivity study has been performed in order to extend these results to various cirrus optical thicknesses and heterogeneities by sampling the cirrus in several ranges of parameters. For four optical thickness classes and four optical heterogeneity classes, we have found that, for nadir observations, the spatial resolution at which the combination of PPHB and HRT effects is the smallest, falls between 100 and 250 m. These spatial resolutions thus appear to be the best choice to retrieve cirrus optical properties with the smallest cloud heterogeneity-related total bias in the thermal infrared. For off-nadir observations, the average total effect is increased and the minimum is shifted to coarser spatial resolutions. |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000405466800001 |
WOS关键词 | OPTIMAL ESTIMATION ALGORITHM ; CLOUD OPTICAL-THICKNESS ; RADIATIVE-TRANSFER ; MARINE STRATOCUMULUS ; EFFECTIVE EMISSIVITY ; INFORMATION-CONTENT ; EFFECTIVE RADIUS ; AVHRR CHANNELS ; INHOMOGENEITY ; MODEL |
WOS类目 | Environmental Sciences ; Meteorology & Atmospheric Sciences |
WOS研究方向 | Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/20546 |
专题 | 地球科学 |
作者单位 | 1.Univ Space Res Assoc, Columbia, MD 21046 USA; 2.NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA; 3.Univ Space Res Assoc, Goddard Earth Sci Technol & Res, Columbia, MD USA; 4.Univ Lille 1, UMR 8518, Lab Opt Atmospher, Villeneuve Dascq, France; 5.Univ Blaise Pascal, UMR 6016, Lab Meteorol Phys, Clermont Ferrand, France; 6.Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol & Dept Phys, Baltimore, MD 21228 USA |
推荐引用方式 GB/T 7714 | Fauchez, Thomas,Platnick, Steven,Meyer, Kerry,et al. Scale dependence of cirrus horizontal heterogeneity effects on TOA measurements - Part I: MODIS brightness temperatures in the thermal infrared[J]. ATMOSPHERIC CHEMISTRY AND PHYSICS,2017,17(13). |
APA | Fauchez, Thomas,Platnick, Steven,Meyer, Kerry,Cornet, Celine,Szczap, Frederic,&Varnai, Tamas.(2017).Scale dependence of cirrus horizontal heterogeneity effects on TOA measurements - Part I: MODIS brightness temperatures in the thermal infrared.ATMOSPHERIC CHEMISTRY AND PHYSICS,17(13). |
MLA | Fauchez, Thomas,et al."Scale dependence of cirrus horizontal heterogeneity effects on TOA measurements - Part I: MODIS brightness temperatures in the thermal infrared".ATMOSPHERIC CHEMISTRY AND PHYSICS 17.13(2017). |
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