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Estimation of liquid water content and water vapor amount in the polar region

极地液态水含量和水蒸气量估算

基本信息

批准号：
61540304
负责人：
KAWAGUCHI Sadao
金额：
$ 1.47万
依托单位：
National Institute of Polar Research
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1988
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61540304/
关键词：
Antarctic Climate Research Liquid water content Water vapor amount Microwave radiometer Satellite AVHRR imagery Discrimination of clouds TOVS.輝度温度放射特性.水循環南極域気象衛星NDAA 逐次代入法

项目摘要

Clouds and water vapor work as an important factors of the climate in the Antarctic. This study aimes to obtain the method to derive liquid water content of clouds and water vapor amounts from groundbased microwave observations and satellite data.1. As for the microwave observation, radiometers of three frequency range, 12, 19 and 37 GHz were examined. From the preliminary observation in Japan, combination of rediometers of three frequency regions works effective to get the cloud information. However, in the polar region, because of small amount of liquid water and water vapor, 12 GHz radiometer was not suitable and 19 GHz radiometer, which was expected to be effective for water vapor measurements, did not offer a meaning value of water vapor. It was shown that the single frequency measurements by the 37 GHz radiometer was enough to derive liquid water content under the polar atmosphere where the amount of water vapor and liquid water are small, if the physical temperature of antenna was monitored.2. The method to discriminate clouds by AVHRR data of NOAA satellite was examined. Since the cloud cover over the snow surface in the polar region is difficult to detect only by the visible reflection or infrared brightness temperature, the differences of infrared brightness temperatures were used. The differences between the brightness temperature in 4 mum region (ch 3) and 10 mum region (ch 4), 10 mum and 12 mum region (ch 5) were used together with the 2 dimentional histogram of the brightness temperature and the difference.3. Atmospheric water vapor amount was derived from the TIROS Operational Veritcal Sounder (TOVS) of NOAA satellite. Since the strong surface inversion affects the analysis, iteration method with considering the surface temperature explicitly was used. Comparing to the aerological data, though the vertical profile shows large disagreements, the column amounts of water vapor agreed within small variations.

云和水蒸气是影响南极气候的重要因素。本研究旨在从地面微波观测和卫星资料中获得云的液态水含量和水蒸气量的方法。在微波观测方面，测试了12、19和37 GHz三个频率范围的辐射计。从日本的初步观测来看，三个频率区的重计组合可以有效地获取云信息。然而，在极地地区，由于液态水和水蒸气的数量较少，12 GHz辐射计不适合，而19 GHz辐射计没有提供水蒸气的意义值，这是预期的有效的水蒸气测量。结果表明，在监测天线的物理温度的情况下，37 GHz辐射计的单频测量足以计算出水汽和液态水量较小的极地大气下的液态水含量。探讨了利用NOAA卫星AVHRR资料进行云区判别的方法。由于仅通过可见光反射或红外亮温难以探测到极地雪面云量，因此采用了红外亮温差。2 .利用4母区（ch 3）与10母区（ch 4）、10母区与12母区（ch 5）的亮度温度差，并结合亮度温度与亮度差的二维直方图。大气水汽量来源于NOAA卫星的TIROS操作垂直测深仪（TOVS）。由于地表强反演影响分析，采用了明确考虑地表温度的迭代法。与气象资料相比，尽管垂直剖面存在较大差异，但水蒸汽柱量在很小的变化范围内一致。