Biases in total precipitable water vapor climatologies from Atmospheric Infrared Sounder and Advanced Microwave Scanning Radiometer
Biases in total precipitable water vapor climatologies from Atmospheric Infrared Sounder and Advanced Microwave Scanning Radiometer
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大气红外探测器和先进微波扫描辐射计的总可降水水汽气候学偏差
DOI：
10.1029/2005jd006598
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发表时间：
2006
影响因子：
--
通讯作者：
M. Chahine
中科院分区：
文献类型：
--
作者：
E. Fetzer;B. Lambrigtsen;A. Eldering;H. Aumann;M. Chahine
[1] 我们研究了共享 Aqua 航天器平台的大气红外探测器 (AIRS) 和高级微波扫描辐射计 (AMSR-E) 实验中总可降水量 (PWV) 的差异。两个系统都提供水面 PWV 的估计值。我们比较了 AIRS 和 AMSR-E PWV，以将 AIRS 反演的不确定性限制为 AIRS 反演红外云分数的函数。两种仪器之间的 PWV 差异很小，红外云分数高达 70% 左右。 AIRS-AMSR-E PWV 差异图随位置和季节而变化。当两台仪器观察相同场景时，观察偏差通常小于 5%。例外情况是冷空气爆发时，AIRS 偏湿 10-20% 或 10-60%（取决于检索处理），以及冬季高纬度地区，AIRS 偏干 5-10%。由于 AIRS 和 AMSR-E 的不同采样特性，采样偏差的符号和大小各不相同。在大多数高纬度地区，AIRS 采样的干燥程度高达 30%，但在副热带层云带中，湿润程度高达 5-15%。在西北太平洋，AIRS 采样的环境比 AMSR-E 潮湿多达 60%。我们假设湿采样和干采样偏差都是由于云对 AIRS 反演方法的影响造成的。这些偏差的符号和大小取决于云的类型以及云与 PWV 之间的关系。 PWV 的这些结果意味着来自 AIRS 的高度分辨水汽的气候学必须考虑影响 AIRS 采样的当地气象过程。
[1] We examine differences in total precipitable water vapor (PWV) from the Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Scanning Radiometer (AMSR-E) experiments sharing the Aqua spacecraft platform. Both systems provide estimates of PWV over water surfaces. We compare AIRS and AMSR-E PWV to constrain AIRS retrieval uncertainties as functions of AIRS retrieved infrared cloud fraction. PWV differences between the two instruments vary only weakly with infrared cloud fraction up to about 70%. Maps of AIRS-AMSR-E PWV differences vary with location and season. Observational biases, when both instruments observe identical scenes, are generally less than 5%. Exceptions are in cold air outbreaks where AIRS is biased moist by 10-20% or 10-60% (depending on retrieval processing) and at high latitudes in winter where AIRS is dry by 5-10%. Sampling biases, from different sampling characteristics of AIRS and AMSR-E, vary in sign and magnitude. AIRS sampling is dry by up to 30% in most high-latitude regions but moist by 5-15% in subtropical stratus cloud belts. Over the northwest Pacific, AIRS samples conditions more moist than AMSR-E by a much as 60%. We hypothesize that both wet and dry sampling biases are due to the effects of clouds on the AIRS retrieval methodology. The sign and magnitude of these biases depend upon the types of cloud present and on the relationship between clouds and PWV. These results for PWV imply that climatologies of height-resolved water vapor from AIRS must take into consideration local meteorological processes affecting AIRS sampling.