Intercomparisons of marine boundary layer cloud properties from the ARM CAP‐MBL campaign and two MODIS cloud products
Intercomparisons of marine boundary layer cloud properties from the ARM CAP‐MBL campaign and two MODIS cloud products
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ARM CAP-MBL 活动和两个 MODIS 云产品的海洋边界层云属性的相互比较
DOI：
10.1002/2016jd025763
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
P. Minnis
中科院分区：
文献类型：
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作者：
Zhibo Zhang;Xiquan Dong;B. Xi;Hua Song;P. Ma;S. Ghan;S. Platnick;P. Minnis
从2009年4月到2010年12月，美国能源部大气辐射测量（ARM）项目在Graciosa岛开展了一项实地观测活动，目标是亚速尔群岛地区的海洋边界层（MBL）云。在本文中，我们对来自ARM移动设备和两个中分辨率成像光谱仪（MODIS）云产品（戈达德太空飞行中心（GSFC）‐MODIS和云与地球辐射能系统‐MODIS）的检索数据进行了MBL云特性的相互比较，即云液化水路径（LWP）、云光学厚度（COT）和云滴有效半径（CER）。共选择63个白天单层MBL云案例进行相互比较。对比结果表明，两种MODIS云产品在COT和CER反演上的一致性较好，相关系数R为0.95，尽管两者在空间采样上存在显著差异。在两种MODIS产品中，基于2.1µm波段（CER2.1）的CER检索值明显大于基于3.7µm波段（CER3.7）的CER检索值。GSFC - MODIS云产品在几个时空尺度上与地面的ARM观测进行了并置和比较。一般来说，搭配越精确，相关性越强。对于选定的63个MBL云案例，GSFC - MODIS LWP和COT反演结果与地面观测结果相当吻合，没有明显偏差，相关系数R分别在0.85和0.70左右。然而，GSFC‐MODIS CER3.7和CER2.1检索结果与地面检索结果的相关性较低（R ~ 0.5）。对于所选的63个案例，它们平均比地面观测值分别大约1.5µm和3.0µm。考虑到MODIS CER反演仅对云顶敏感，偏差仅减小0.5µm。
From April 2009 to December 2010, the Department of Energy Atmospheric Radiation Measurement (ARM) program carried out an observational field campaign on Graciosa Island, targeting the marine boundary layer (MBL) clouds over the Azores region. In this paper, we present an intercomparison of the MBL cloud properties, namely, cloud liquid water path (LWP), cloud optical thickness (COT), and cloud‐droplet effective radius (CER), among retrievals from the ARM mobile facility and two Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products (Goddard Space Flight Center (GSFC)‐MODIS and Clouds and Earth's Radiant Energy System‐MODIS). A total of 63 daytime single‐layer MBL cloud cases are selected for intercomparison. Comparison of collocated retrievals indicates that the two MODIS cloud products agree well on both COT and CER retrievals, with the correlation coefficient R > 0.95, despite their significant difference in spatial sampling. In both MODIS products, the CER retrievals based on the 2.1 µm band (CER2.1) are significantly larger than those based on the 3.7 µm band (CER3.7). The GSFC‐MODIS cloud product is collocated and compared with ground‐based ARM observations at several temporal‐spatial scales. In general, the correlation increases with more precise collocation. For the 63 selected MBL cloud cases, the GSFC‐MODIS LWP and COT retrievals agree reasonably well with the ground‐based observations with no apparent bias and correlation coefficient R around 0.85 and 0.70, respectively. However, GSFC‐MODIS CER3.7 and CER2.1 retrievals have a lower correlation (R ~ 0.5) with the ground‐based retrievals. For the 63 selected cases, they are on average larger than ground observations by about 1.5 µm and 3.0 µm, respectively. Taking into account that the MODIS CER retrievals are only sensitive to cloud top reduces the bias only by 0.5 µm.