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全文摘要次数: 243 全文下载次数: 294
引用本文:

DOI:

10.11834/jrs.20210088

收稿日期:

2020-04-01

修改日期:

2020-08-07

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89GHz多入射角亮温差反演海冰密集度的可行性分析
吴若男, 刘浩
国家空间科学中心
摘要:

被动微波遥感是目前进行海冰密集度观测的重要方式,ASI算法利用AMSR-E的89GHz双极化的亮温可以获得目前SIC产品中最高空间分辨率6.25km,但是需要低频数据进行大气校正。SMOS的多角度观测方式为本文提供了一种新的设想:利用89GHz波段一维综合孔径辐射计顺轨扫描配合机械扫描可以实现对单个像元点的多入射角观测,充分利用多入射角下的亮温信息可以弥补观测过程中海冰与海水亮温信息的混淆,提高SIC的反演精度,并且可以实现高空间分辨率。因此本文开展89GHz多入射角亮温信息观测北极海冰密集度的可行性研究。第一步构建星载观测海冰辐射亮温仿真系统及利用FY-3C星搭载的微波湿度计的89GHz通道实测的垂直极化亮温数据,开展了89GHz亮温与角度敏感性分析;第二步,推导建立了基于89GHz角度亮温差的SIC反演算法,结合ECMWF的SIC产品及亮温仿真系统完成了初步反演验证。验证结果表明,利用入射角亮温差可以实现海冰密集度的反演,利用多组入射角组合进行最小均方根加权平均后处理可以最大程度的降低SIC的反演误差。输入的高斯白噪声为2K时,可以获得5%的SIC误差。最终结果证明利用连续角度亮温差进行SIC反演,可以充分扩大海水与海冰的区分。

Feasibility Analysis of Retrieving Sea Ice Concentration by Multi-incidence Angle Brightness Temperature at 89GHz
Abstract:

Passive microwave remote sensing is an important method to observe the sea ice concentration. ASI algorithm can obtain the highest spatial resolution of 6.25km2 in current SIC products by using the dual-polarized brightness temperature of AMSR-E at 89GHz, but low-frequency data is needed for weather filter. Multi-angle observation of SMOS provides a new approach for observing the sea ice concentration: at the 89GHz, using 1-D comprehensive aperture radiometer along the orbit with mechanical scanning can realize the multi-incident angle observation for a single pixel point, making full use of the brightness temperature information under the multi-incident angle to make up for the confusion of sea ice and seawater brightness temperature information in the observation process, improving the precision of SIC retrieving, and achieving high spatial resolution. Therefore, a feasibility study was carried out to observe the arctic sea ice concentration with the brightness temperature information from multi-incident angle at 89GHz. The first step is to build a simulation system for space-borne observation of sea-ice radiant brightness temperature and to use the measured data of the 89GHz channel from the FY-3C /MWHS, carrying out the sensitivity analysis between brightness temperature and angle at 89GHz. The second step is to deduce and establish the SIC retrieving algorithm based on the angle brightness temperature difference at 89GHz, and complete the preliminary retrieving verification by combining the SIC product of ECMWF and the brightness temperature simulation system. The results show that the retrieving of sea ice concentration can be realized by using the incident angle brightness temperature difference, and the minimum root-mean-square (RMS) weighted average post-processing by using the combination of multi-incidence angle can minimize the retrieving error of SIC. When the input Gaussian white noise is 2K, 5% SIC error can be obtained. The final results show that SIC retrieving with the combination of multi-incidence angle can fully expand the distinction between sea water and sea ice.

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