1999 Fiscal Year Final Research Report Summary
Ozone and water vapor observations in the tropical Pacific
| Project/Area Number |
10041103
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
SHIOTANI Masato Graduate School of Environmental Earth Science, Hokkaido University, Prof., 大学院・地球環境科学研究科, 教授 (50192604)
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| Co-Investigator(Kenkyū-buntansha) |
NISHI Noriyuki Graduate School of Science, Kyoto University, instructor, 大学院・理学研究科, 助手 (00222183)
OGAWA Toshihiro Agency of Japan Earth Observation Research Center, National Space Development, Research Director, 地球観測データ解析研究センター, 研究ディレクター (70011616)
HASEBE Fumio Graduate School of Environmental Earth Science, Ibaragi University, Assoc. Prof., 理学部・地球生命環境科学科, 助教授 (00261735)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Ozone / Water Vapor / Equatorial Atmosphere / Equatorial waves / Stratosphere-Troposphere exchange / Tropopause |
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| Research Abstract |
On the basis of this financial support during the period of 1998 and 1999, we have conducted observation campaigns three times at San Cristobal, the Galapagos Islands in the eastern Pacific, and two times at Christmas Island, Kiribati in the central Pacific. We are now making intensive analyses of the data from these campaigns, and have learned the following preliminary knowledge so far.
1. By comparing data from San Cristobal with Singapore in the western Pacific, we found at the two stations that there exist clear annual variations of the tropopause properties, such as low pressure, high altitude and low temperature during the northern winter season; however, the correspondence expected from the sea surface temperature variations is not clear.
2. Results from water vapor measurements at San Cristobal show, contrary to expectations, clear evidence of saturation conditions around the tropopause in March. Those in September sometimes show unsaturation conditions, but it is a time when downward phase propagation of the equatorial Kelvin wave, providing dry and ozone-rich air intrusion from the stratosphere.
3. Tropospheric ozone distribution at San Cristobal is characterized as a near constant (about 30 ppb) profile in March-April, but as a increase up to 6 - 7 km (50ppb) from the surface (20ppb). This may suggest that the stratospheric ozone is leakier in September due tomore vigorous equatorial wave activity.
4. Radiosonde and ozonesonde observations from the research vessel, we have found layered structures in the lower troposphere up to about 5km from the surface; these are characterized as a dry and ozone-rich atmosphere. Around these layers, the northerly wind is dominated, suggesting a relation to the Inter-Tropical Convergence Zone (ITCZ) situated north of the research vessel. This feature is also observed in the ozone data at San Cristobal and Christmas island.
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