2004 Fiscal Year Final Research Report Summary
Uncertainty of cloud parameters on satellite estimation of radiation budget in climate change study
| Project/Area Number |
14380241
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | Chiba University |
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Principal Investigator |
TAKAMURA Tamio Chiba University, Center for Environmental Remote Sensing, Professor, 環境リモートセンシング研究センター, 教授 (40272356)
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| Co-Investigator(Kenkyū-buntansha) |
KUZE Hiroak Chiba University, Center for Environmental Remote Sensing, Professor, 環境リモートセンシング研究センター, 教授 (00169997)
TAKANO Toshiaki Chiba University, Graduate School of Science and Teehnobgy, Associate Prof., 大学院・自然科学研究科, 助教授 (40183058)
NAKAJIMA Teruyuki University Tokyo, Center for Climate System Research, Professor, director, 気候システム研究センター, 教授 (60124608)
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| Project Period (FY) |
2002 – 2004
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| Keywords | radiation budget / climate change / optical characteristics of cloud / cloud radar / LIDAR / radiative forcing |
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| Research Abstract |
We have the research results as follows,
[Review and re-examination of optical characteristics of clouds for estimating the radiation budget and cloud radiative forcing with high accuracy]
Up to now, we have continued to estimate the hourly data of cloudiness, cloud optical thickness, surface brightness temperature and downward solar radiation at the surface using the GMS-5 from 1996. These products should be validated with the data observed at the surface. Our team has been operating the SKYNET observation network in the East Asia for the research of cloud, aerosol and radiation issues in the climate change. The comparison gave two distinguished trends ; for clear days, the comparison shows the quite good agreement, but for cloudy days it has large discrepancies with more than 50W/m2 in some cases. This would bring serious effects on the estimation of radiation budget. So we have made the reason clear and improved the algorithm for estimation.
The most important parameters for giving the
… More
se errors are ;
(1)sensitivity change of sensor response, (2)digitization noise, and (3)inhomogeneity of cloud.
Regarding the item (1), we have already analyzed this trend of degradation of GMS-5 and got the decrease of sensitivity with several percents per year. In this research, we have quantitatively estimated the effect compared with MODIS data. Since the GMS visible channel has a low resolution (6bit, 64 steps), and a second-order polynomial response for the input radiance, it is highly sensitive for the lower reflected radiance, in other words, a relatively thin cloud, and the poor sensitive for the high reflected radiance, such as thick clouds. The comparison with MODIS data gave the quantitative difference between them. Also the MODIS and the GMS take the same images of cloud simultaneously, but the satellite zenith angles are different which means the possibility of the radiance received from the cloud can give the error if the cloud is not plane parallel. The effect of 3-dimensional structure of cloud has been estimated. These analytical results in the project reflect our algorithms to estimate the cloud parameters and radiation budget. Less
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[Book] エアロゾル用語集2004
Author(s)
高村民雄(共著)
Total Pages
270
Publisher
京都大学学術出版会
Description
「研究成果報告書概要(和文)」より
