Characterization of Water Vapor and Clouds During the Next-Generation Aircraft Remote Sensing for Validation (NARVAL) South Studies
Characterization of Water Vapor and Clouds During the Next-Generation Aircraft Remote Sensing for Validation (NARVAL) South Studies
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DOI：
10.1109/jstars.2017.2687943
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发表时间：
2017-06
影响因子：
5.5
通讯作者：
Sabrina Schnitt;E. Orlandi;M. Mech;A. Ehrlich;S. Crewell
中科院分区：
文献类型：
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作者：
Sabrina Schnitt;E. Orlandi;M. Mech;A. Ehrlich;S. Crewell
浅层信风云是气候模型中最大的不确定性之一。由于通过常规观测评估这些云层存在困难，因此于 2013 年 12 月利用德国高空长程研究飞机 (HALO) 进行了下一代飞机遥感验证活动。在这里，我们利用 HALO 主动和被动微波套件以及 HALO-SR 测量的光谱分辨太阳辐射 (SR) 的协同作用来表征加勒比海的浅云。基于 HALO-SR 开发的云掩模，可以检测到 $\sim 4100$ 内的约 12 000 个云剖面，其中约 $70\,\%$ 的云长度小于 2 公里。与被动微波测量的相应测量表明，这些小云也含有很少的水，其中 36% 的云显示液态水路径 (LWP) 小于 $\text{50 g}\cdot \text{m}^{-2}$。我们表明，由于其分辨率较低，这些小而薄的云很难通过特殊传感器微波成像仪/发声器的卫星观测来表征。中等成像光谱辐射计测量能够识别较小的云，但当云开始沉淀时，LWP 会受到影响，机载 35 GHz 雷达检测到的约 7% 的云就是这种情况。
Shallow trade wind clouds pose one of the largest uncertainties in climate models. Due to the difficulties in assessing these clouds with routine observations the next-generation aircraft remote-sensing for validation campaign with the German High Altitude and LOng range research aircraft (HALO) took place in December 2013. Here we take advantage of the synergy of the HALO active and passive microwave package as well as spectrally resolved solar radiation (SR) measured by HALO-SR to characterize shallow clouds in the Caribbean. Based on a cloud mask developed from HALO-SR, about 12 000 cloudy profiles within $\sim 4100$ individual clouds could be detected with about $70\,\%$ of them having a length of less than 2 km. Corresponding measurements with passive microwave measurements reveal that these small clouds also contain little water with 36% of the clouds showing a liquid water path (LWP) of less than $\text{50 g}\cdot \text{m}^{-2}$. We show that these small and thin clouds are difficult to characterize with satellite observations by the special sensor microwave imager/sounder due to its coarse resolution. Moderate imaging spectroradiometer measurements are able to identify the smaller clouds but suffer in terms of LWP when clouds start precipitating, which is the case for about 7% of the clouds as detected by the airborne 35 GHz radar.