The CALIPSO version 4 automated aerosol classification and lidar ratio selection algorithm
The CALIPSO version 4 automated aerosol classification and lidar ratio selection algorithm
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DOI：
10.5194/amt-11-6107-2018
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发表时间：
2018-11-12
影响因子：
3.8
通讯作者：
Magill, Brian E.
中科院分区：
文献类型：
--
作者：
Kim, Man-Hae;Omar, Ali H.;Magill, Brian E.
2016年11月发布的云气溶胶激光雷达正交偏振（CALIOP）4.10（V4）2级气溶胶数据产品包括对气溶胶子类型和激光雷达比率选择算法的实质性改进。这些改进沿着气溶胶光学厚度（AOD）的变化进行描述。V4 2级气溶胶产品最根本的变化是采用了一种新的算法来识别平流层中的气溶胶亚型。平流层气溶胶有四种亚型：极地平流层气溶胶（PSA）、火山灰、硫酸盐/其他和烟雾。对流层气溶胶子类型算法也得到了改进，增加了以下改进：（1）现在允许在极地地区使用所有气溶胶子类型，而版本3（V3）算法只允许清洁的大陆气溶胶和污染的大陆气溶胶;（2）引入了一个新的“海洋尘埃”气溶胶子类型，代表海洋表面附近的尘埃和海洋气溶胶的混合物;及（3）“污染大陆”及“烟雾”亚型已分别改名为“污染大陆/烟雾”及“上升烟雾”。V4还修改了清洁海洋、尘埃、清洁大陆和高烟子类型的激光雷达比率。作为V4更新的结果，对于夜间（白天），通过CALIOP检索的平均532 nm AOD增加了0.044（0.036）或52%（40%）。激光雷达比率的修正是影响气溶胶光学厚度从V3到V4变化的最重要因素，尤其是在无云的天空中。初步验证研究表明，与V3相比，V4中CALIOP和AERONET-MODIS（海洋）之间的AOD差异有所减少。
The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) version 4.10 (V4) level 2 aerosol data products, released in November 2016, include substantial improvements to the aerosol subtyping and lidar ratio selection algorithms. These improvements are described along with resulting changes in aerosol optical depth (AOD). The most fundamental change in the V4 level 2 aerosol products is a new algorithm to identify aerosol subtypes in the stratosphere. Four aerosol subtypes are introduced for stratospheric aerosols: polar stratospheric aerosol (PSA), volcanic ash, sulfate/other, and smoke. The tropospheric aerosol subtyping algorithm was also improved by adding the following enhancements: (1) all aerosol subtypes are now allowed over polar regions, whereas the version 3 (V3) algorithm allowed only clean continental and polluted continental aerosols; (2) a new "dusty marine" aerosol subtype is introduced, representing mixtures of dust and marine aerosols near the ocean surface; and (3) the "polluted continental" and "smoke" subtypes have been renamed "polluted continental/smoke" and "elevated smoke", respectively. V4 also revises the lidar ratios for clean marine, dust, clean continental, and elevated smoke subtypes. As a consequence of the V4 updates, the mean 532 nm AOD retrieved by CALIOP has increased by 0.044 (0.036) or 52 % (40 %) for nighttime (daytime). Lidar ratio revisions are the most influential factor for AOD changes from V3 to V4, especially for cloud-free skies. Preliminary validation studies show that the AOD discrepancies between CALIOP and AERONET-MODIS (ocean) are reduced in V4 compared to V3.