1993 Fiscal Year Final Research Report Summary
Improvement of GPS positioning accuracy by using water vapor radiometers
| Project/Area Number |
03402014
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体地球物理学
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| Research Institution | Kyoto University |
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Principal Investigator |
TANAKA Torao Kyoto University, Disas. Prev. Res. Inst., Professor, 防災研究所, 教授 (40027222)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Kajuro Kyoto University, DPRI, Research Associtate, 防災研究所, 助手 (20135510)
HIRAHARA Kazuro Kyoto University, DPRI, Associate Professor, 防災研究所, 助教授 (40165197)
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| Project Period (FY) |
1991 – 1993
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| Keywords | GPS / Water Vapor Radiometer / Remote Sensing / Microwave Propagation Delay / Relative Positioning / Radiosonde / Meteorological Observation |
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| Research Abstract |
In order to improve the positioning accuracy by GPS to the order of mm, precise estimate of wicrowave propagation delay due to water vapor in the troposphere is essential. Water vapor radiometers are considered one of the most promising instrument for this purpose, so that we have introduced two water vapor radiometers (RADIOMETRICS ; MODEL WVR-1000) in 1991 and started concurrent observations with radiosonde and GPS observations. After the sensitivity and stability of the WVRs had been checked, retrieval coefficients in the algorithm for the transformation from observed brightness temperature of the sky to the amount of water vapor in the sight direction have been determined. Using these retrieval coefficients and the observational results from the WVRs we investigated the improvement of GPS relative positioning accuracy. It is apparent that WVRs are useful to improve the GPS positioning accuracy, namely the repeatability of daily baseline solutions, in rainy and hot seasons such as June, July and August. But in dry and cool seasons such as from October to April there cannot be seen any apparent improvement in the daily repeatability, while long-term reliabilty of the solutions is considered to have been upgraded. In future WVRs will be required to use in order to realize quick and high accuracy relative positioning.
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