In Situ and Lidar Observations of Tropopause Subvisible Cirrus Clouds During TC4
In Situ and Lidar Observations of Tropopause Subvisible Cirrus Clouds During TC4
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DOI：
10.1029/2009jd013093
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发表时间：
2010-05
影响因子：
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通讯作者：
S. Davis;D. Hlavka;E. Jensen;K. Rosenlof;Qiong Yang;S. Schmidt;S. Borrmann;Wiebke Frey;Paul Lawson;H. Voemel;T. P. Bui
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文献类型：
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作者：
S. Davis;D. Hlavka;E. Jensen;K. Rosenlof;Qiong Yang;S. Schmidt;S. Borrmann;Wiebke Frey;Paul Lawson;H. Voemel;T. P. Bui
[1]在2007年7月至8月的热带成分、云和气候耦合(TC4)试验期间，NASA WB-57F和ER-2飞机协调飞行，穿过中美洲太平洋海岸对流层顶次可见卷云(SVC)层。ER-2飞机配备了一个遥感有效载荷，其中包括云物理激光雷达(CPL)。WB-57F有效载荷包括云微物理和痕量气体测量，在ER-2飞越后不久，飞机通过SVC层进行了四次垂直剖面。现场和遥感数据被用来量化SVC层的气象和微物理特性，并将这些数据与以前进行的有限的SVC测量集进行比较。发现遇到的层特别稀薄，光学厚度(τ)在10−4-10−3之间。根据现场和其他气象资料，计算了∼0.0 5-0.1Kday−1的辐射加热率扰动。这些加热率比之前估计的对流层顶SVC要小，这与本研究中较小的τ是一致的。基于其他TC4航班CPL数据的覆盖率统计数据表明，这片云在抽样人口中并不是异常值。具有类似于此处所示特性的SVC低于CALIPSO等天基激光雷达的探测下限，与TC4统计数据的比较表明，在使用CALIPSO数据进行的研究中，大部分(>；50%)对流层顶Svc(τ；lt；0.01)可能无法解释。
[1] During the Tropical Composition, Clouds, and Climate Coupling (TC4) experiment in July–August 2007, the NASA WB-57F and ER-2 aircraft made coordinated flights through a tropopause subvisible cirrus (SVC) layer off the Pacific Coast of Central America. The ER-2 aircraft was equipped with a remote sensing payload that included the cloud physics lidar (CPL). The WB-57F payload included cloud microphysical and trace gas measurements, and the aircraft made four vertical profiles through the SVC layer shortly after the ER-2 flew over. The in situ and remotely sensed data are used to quantify the meteorological and microphysical properties of the SVC layer, and these data are compared to the limited set of SVC measurements that have previously been made. It is found that the layer encountered was particularly tenuous, with optical depths (τ) between about 10−4 and 10−3. From the in situ and other meteorological data, radiative heating rate perturbations of ∼0.05–0.1 K day−1 are calculated. These heating rates are smaller than previous estimates for tropopause SVC, consistent with the smaller τ in the present study. Coverage statistics based on CPL data from other TC4 flights indicate that this cloud was not an outlier among the sampled population. SVC with properties similar to the one presented here are below the detection limit of space-based lidars such as CALIPSO, and a comparison with the TC4 statistics suggests that a majority (>50%) of tropopause SVC (with τ < 0.01) could be unaccounted for in studies using CALIPSO data.