Retrieval of stratospheric temperatures from Atmospheric Infrared Sounder radiance measurements for gravity wave studies
Retrieval of stratospheric temperatures from Atmospheric Infrared Sounder radiance measurements for gravity wave studies
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DOI：
10.1029/2008jd011241
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发表时间：
2009-04
影响因子：
--
通讯作者：
L. Hoffmann;M. Alexander
中科院分区：
文献类型：
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作者：
L. Hoffmann;M. Alexander
[1]自2002年夏季以来，美国国家航空航天局（NASA）Aqua卫星上的大气红外探测器（AIRS）一直在连续测量中红外最低点和次临边辐射光谱。这些测量被用来检索三维平流层温度分布，通过应用一个新的快速前进模型AIRS和伴随的最佳估计检索处理器。本文提出的反演方案不需要像AIRS业务分析那样同时观测微波仪器。相反，在仪器的全部水平采样能力下进行独立的检索。与AIRS业务数据相比，水平分辨率在沿着和跨航迹方向上提高了3倍。在20 ~ 60 km的高度范围内，单个温度测量的总反演误差为1.6 ~ 3.0K。在相同的垂直范围内，检索噪声为1.4至2.1 K。先验信息对反演结果的贡献小于1%~ 2%，观测的垂直分辨率约为7 ~ 15 km。温度测量成功地与ECMWF业务分析和AIRS业务水平2数据进行了比较。新的温度数据集非常适合研究平流层重力波。本文介绍了2003年1月澳大利亚达尔文附近深对流引起的小尺度重力波的AIRS观测结果。详细分析了2005年6月发生在安第斯山脉的一次强山波事件。来自新的数据集的温度扰动进行了比较，从AIRS业务水平2的数据和符合测量的高分辨率动力学临边探测器（HIRDLS）的结果。当垂直波长小于10 km时，新的反演方法对波的扰动没有响应。对于15 km的垂直波长，振幅衰减为2倍。对于大于20 km的垂直波长，AIRS显示出与HIRDLS非常相似的波结构，并且还具有提供水平相锋信息的优点。新的全分辨率反演的数据更适合重力波研究比AIRS业务分析的结果。
[1] The Atmospheric Infrared Sounder (AIRS) on board the National Aeronautics and Space Administration's (NASA's) Aqua satellite has been continuously measuring mid-infrared nadir and sub-limb radiance spectra since summer of 2002. These measurements are utilized to retrieve three-dimensional stratospheric temperature distributions by applying a new fast forward model for AIRS and an accompanying optimal estimation retrieval processor. The retrieval scheme presented in this article does not require simultaneous observations of microwave instruments like the AIRS operational analyses. Instead, independent retrievals are carried out at the full horizontal sampling capacity of the instrument. Horizontal resolution is enhanced by a factor 3 in along- and across-track directions compared with the AIRS operational data. The total retrieval error of the individual temperature measurements is 1.6 to 3.0 K in the altitude range from 20 to 60 km. Retrieval noise is 1.4 to 2.1 K in the same vertical range. Contribution of a priori information to the retrieval results is less than 1% to 2% and the vertical resolution of the observations is about 7 to 15 km. The temperature measurements are successfully compared with ECMWF operational analyses and AIRS operational Level 2 data. The new temperature data set is well suited for studies of stratospheric gravity waves. We present AIRS observations of small-scale gravity waves induced by deep convection near Darwin, Australia, in January 2003. A strong mountain wave event over the Andes in June 2005 is analyzed in detail. Temperature perturbations derived from the new data set are compared with results from the AIRS operational Level 2 data and coincident measurements of the High Resolution Dynamics Limb Sounder (HIRDLS). The new retrieval does not show response to wave perturbations if the vertical wavelength is below 10 km. For 15 km vertical wavelength, the amplitudes are damped by a factor of two. For vertical wavelengths of greater than 20 km, AIRS shows very similar wave structure to HIRDLS and also has the advantage of providing horizontal phase front information. Data from the new full-resolution retrieval are far more suitable for gravity wave studies than results from the AIRS operational analysis.