A new multispectral cloud retrieval method for ship‐based solar transmissivity measurements
A new multispectral cloud retrieval method for ship‐based solar transmissivity measurements
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一种用于船基太阳透射率测量的新型多光谱云反演方法
DOI：
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
M. Wendisch
中科院分区：
文献类型：
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作者：
M. Brückner;B. Pospichal;A. Macke;M. Wendisch
在德国Leibniz网络OCEANET项目中，进行了船载激光雷达和微波遥感以及使用CORAS的光谱天顶辐射观测。在三次巡航中，覆盖了北纬50°至南纬50°之间的纬度。本文提出了一种利用CORAS卫星资料反演云光学厚度τ和云滴有效半径reff的新方法。该方法匹配CORAS测量的光谱透射比在六个波长与建模的透射率。这种检索快速而准确，因此适合于业务目的。新方法避免了现有云反演的模糊性，并减少了测量不确定性的影响。它适用于均匀和非均匀的液态水和卷云。在边界层液态水云中，反演的有效半径变化较大，而在卷云中，它是相当恒定的。此外，液态水的路径LWP的推导和比较，从微波辐射计的数据。新的反演往往高估LWP厚液态水云，但略低估LWP薄云。所提出的方法不能应用于混合相云。液态水云的τ和reff的最大反演范围分别为τ 80和reff 30 μm，卷云的τ和reff的反演范围分别为τ 10和reff 60 μm。
Within the German Leibniz‐network OCEANET project, ship‐based lidar and microwave remote sensing as well as spectral zenith radiance observations with the COmpact RAdiation measurements System (CORAS) were performed. During three cruises latitudes between 50°N and 50°S were covered. A new spectral retrieval method to derive the cloud optical thickness τ and the droplet effective radius reff using CORAS measurements is developed. The method matches CORAS measurements of ratios of spectral transmissivity at six wavelengths with modeled transmissivities. This retrieval is fast and accurate and thus suitable for operational purposes. The new approach circumvents ambiguities of existing cloud retrievals and reduces the influence of measurement uncertainties. It is applied to homogenous and heterogeneous liquid water and cirrus clouds. In boundary layer liquid water clouds, the retrieved effective radius was more variable, whereas in the cirrus it was rather constant. Furthermore, the liquid water path LWP was derived and compared to data from a microwave radiometer. The new retrieval tends to overestimate LWP for thick liquid water clouds but slightly underestimate LWP for thin clouds. The presented method cannot be applied to mixed‐phase clouds. The maximum retrieval of τ and reff for liquid water clouds is 80 in τ and 30 μm in reff, respectively; for cirrus clouds the limitations of the retrieval are 10 in τ and 60 μm in reff.
利用地面成像光谱法反演卷云光学厚度并评估冰晶形状
影响因子：
3.8
作者：
Schäfer;E. Bierwirth;A. Ehrlich;F. Heyner;M. Wendisch
通讯作者：
M. Wendisch