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Hokkaido University Collection of Scholarly and Academic Papers >
Graduate School of Environmental Science / Faculty of Environmental Earth Science >
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Representation of the tropical stratospheric zonal wind in global atmospheric reanalyses
This item is licensed under:Creative Commons Attribution 3.0 Unported
| Title: | Representation of the tropical stratospheric zonal wind in global atmospheric reanalyses |
| Authors: | Kawatani, Yoshio Browse this author →KAKEN DB | | Hamilton, Kevin Browse this author | | Miyazaki, Kazuyuki Browse this author →KAKEN DB | | Fujiwara, Masatomo Browse this author →KAKEN DB | | Anstey, James A. Browse this author |
| Issue Date: | 2016 |
| Publisher: | Copernicus Publications on behalf of the European Geosciences Union (EGU) |
| Journal Title: | Atmospheric Chemistry and Physics |
| Volume: | 16 |
| Issue: | 11 |
| Start Page: | 6681 |
| End Page: | 6699 |
| Publisher DOI: | 10.5194/acp-16-6681-2016 |
| Abstract: | This paper reports on a project to compare the representation of the monthly-mean zonal wind in the equatorial stratosphere among major global atmospheric reanalysis data sets. The degree of disagreement among the reanalyses is characterized by the standard deviation (SD) of the monthly-mean zonal wind and this depends on latitude, longitude, height, and the phase of the quasi-biennial oscillation (QBO). At each height the SD displays a prominent equatorial maximum, indicating the particularly challenging nature of the reanalysis problem in the low-latitude stratosphere. At 50–70 hPa the geographical distributions of SD are closely related to the density of radiosonde observations. The largest SD values are over the central Pacific, where few in situ observations are available. At 10–20 hPa the spread among the reanalyses and differences with in situ observations both depend significantly on the QBO phase. Notably the easterly-to-westerly phase transitions in all the reanalyses except MERRA are delayed relative to those directly observed in Singapore. In addition, the timing of the easterlyto- westerly phase transitions displays considerable variability among the different reanalyses and this spread is much larger than for the timing of the westerly-to-easterly phase changes. The eddy component in the monthly-mean zonal wind near the Equator is dominated by zonal wavenumber 1 and 2 quasi-stationary planetary waves propagating from midlatitudes in the westerly phase of the QBO. There generally is considerable disagreement among the reanalyses in the details of the quasi-stationary waves near the Equator. At each level, there is a tendency for the agreement to be best near the longitude of Singapore, suggesting that the Singapore observations act as a strong constraint on all the reanalyses. Our measures of the quality of the reanalysis clearly show systematic improvement over the period considered (1979–2012). The SD among the reanalysis declines significantly over the record, although the geographical pattern of SD remains nearly constant. |
| Rights: | https://creativecommons.org/licenses/by/3.0/ |
| Type: | article |
| URI: | http://hdl.handle.net/2115/64644 |
| Appears in Collections: | 環境科学院・地球環境科学研究院 (Graduate School of Environmental Science / Faculty of Environmental Earth Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 藤原 正智
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