Intercomparison of multiple years of MODIS, MISR and radar cloud-top heights
Intercomparison of multiple years of MODIS, MISR and radar cloud-top heights
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DOI：
10.5194/angeo-23-2415-2005
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发表时间：
2005-10
影响因子：
1.9
通讯作者：
C. Naud;J. Muller;E. Clothiaux;B. Baum;W. Menzel
中科院分区：
文献类型：
--
作者：
C. Naud;J. Muller;E. Clothiaux;B. Baum;W. Menzel
摘要。雷达云顶高度在英国奇尔博尔顿大气和无线电研究设施（CFARR）和美国ARM南部大平原站点（SGP）使用毫米波云雷达和相同的算法进行检索。将得到的云顶高度与MODIS和MISR检索的2000年3月至2003年10月的云顶高度进行比较。这两种成像仪器都位于1999年发射的美国宇航局地球观测系统（EOS） Terra平台上。MODIS和MISR云顶产品来自覆盖整个任务的最新系列（分别为4和3）。每个地面站点的云特征不同，SGP站点的云通常分布在较高的高度，而CFARR站点则出现更多的破碎云或多层云。由于在这种情况下难以保证地面和卫星测量指向相同的云层，因此提出了一种自动消除云层破碎场景的方法。MODIS云顶高度与雷达云顶高度的对比表明，MODIS云顶高度与雷达云顶高度在1km左右的范围内基本一致。然而，对于低空云层，这种精度下降到近3公里。MISR云顶高度与雷达云顶高度吻合在0.6 km以内，符合理论预期。在单层云情况下，MODIS和MISR云顶高度在1 km以内趋于一致。这一比较也揭示了2001年期间雷达灵敏度的损失导致CFARR仪器在高层云顶高度测量上精度降低。关键词。大气成分和结构（仪器和技术）
Abstract. Radar cloud-top heights were retrieved at both the Chilbolton Facility for Atmospheric and Radio Research, UK (CFARR) and the ARM Southern Great Plain site, USA (SGP), using millimetre wave cloud radars and identical algorithms. The resulting cloud-top heights were used for comparison with MODIS and MISR retrieved cloud-top heights, from March 2000 to October 2003. Both imaging instruments reside on the NASA Earth Observing System (EOS) Terra platform launched in 1999. MODIS and MISR cloud-top products were from the recent collections (4 and 3, respectively) that cover the entire mission. The cloud characteristics are different at each ground site, with clouds generally residing at higher altitudes at SGP, but with a greater occurrence of broken or multilayered clouds at CFARR. A method is presented to automatically eliminate scenes where clouds are of a broken nature, since it is difficult in these conditions to ensure that ground-based and satellite measurements refer to the same cloud deck. The intercomparison between MODIS and radar cloud-top heights reveals that MODIS cloud-top heights agree with radar within about 1km for mid- and high-level clouds. However, this accuracy is degraded to nearly 3 km for low-level clouds. MISR cloud-top heights are found to agree with radar cloud-top heights to within 0.6 km, which is in line with theoretical expectations. In single-level cloud situations MODIS and MISR cloud-top heights tend to agree within 1 km. This comparison also reveals that the loss of radar sensitivity during 2001 resulted in the CFARR instrument being less accurate for high-level cloud-top height measurements. Keywords. Atmospheric composition and structure (Instruments and techniques)