Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses
The momentum forcing of the QBO (quasi-biennial oscillation) by equatorial waves is estimated using recent reanalyses. Based on the estimation using the conventional pressure-level data sets, the forcing by the Kelvin waves (3–9 m s<sup>−1</sup> month<sup&g...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2015-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/15/6577/2015/acp-15-6577-2015.pdf |
| _version_ | 1817971388923772928 |
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| author | Y.-H. Kim H.-Y. Chun |
| author_facet | Y.-H. Kim H.-Y. Chun |
| author_sort | Y.-H. Kim |
| collection | DOAJ |
| description | The momentum forcing of the QBO (quasi-biennial oscillation) by equatorial waves is estimated
using recent reanalyses. Based on the estimation using the
conventional pressure-level data sets, the forcing by the Kelvin
waves (3–9 m s<sup>−1</sup> month<sup>−1</sup>) dominates the net
forcing by all equatorial wave modes (3–11 m s<sup>−1</sup> month<sup>−1</sup>)
in the easterly-to-westerly transition phase at 30 hPa.
In the opposite phase,
the net forcing by equatorial wave modes is small
(1–5 m s<sup>−1</sup> month<sup>−1</sup>). By comparing the results
with those from the native model-level data set of the
ERA-Interim reanalysis, it is suggested that the use of
conventional-level data causes the Kelvin wave forcing to be
underestimated by 2–4 m s<sup>−1</sup> month<sup>−1</sup>. The
momentum forcing by mesoscale gravity waves, which are
unresolved in the reanalyses, is deduced from the residual of
the zonal wind tendency equation. In the easterly-to-westerly
transition phase at 30 hPa, the mesoscale gravity wave forcing is
found to be smaller than the resolved wave forcing, whereas the
gravity wave forcing dominates over the resolved wave forcing in
the opposite phase. Finally, we discuss the uncertainties in
the wave forcing estimates using the reanalyses. |
| first_indexed | 2024-04-13T20:46:11Z |
| format | Article |
| id | doaj.art-70063152013e4e95bfc3aeb812208d57 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-13T20:46:11Z |
| publishDate | 2015-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-70063152013e4e95bfc3aeb812208d572022-12-22T02:30:41ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242015-06-0115126577658710.5194/acp-15-6577-2015Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalysesY.-H. Kim0H.-Y. Chun1Department of Atmospheric Sciences, Yonsei University, Seoul, South KoreaDepartment of Atmospheric Sciences, Yonsei University, Seoul, South KoreaThe momentum forcing of the QBO (quasi-biennial oscillation) by equatorial waves is estimated using recent reanalyses. Based on the estimation using the conventional pressure-level data sets, the forcing by the Kelvin waves (3–9 m s<sup>−1</sup> month<sup>−1</sup>) dominates the net forcing by all equatorial wave modes (3–11 m s<sup>−1</sup> month<sup>−1</sup>) in the easterly-to-westerly transition phase at 30 hPa. In the opposite phase, the net forcing by equatorial wave modes is small (1–5 m s<sup>−1</sup> month<sup>−1</sup>). By comparing the results with those from the native model-level data set of the ERA-Interim reanalysis, it is suggested that the use of conventional-level data causes the Kelvin wave forcing to be underestimated by 2–4 m s<sup>−1</sup> month<sup>−1</sup>. The momentum forcing by mesoscale gravity waves, which are unresolved in the reanalyses, is deduced from the residual of the zonal wind tendency equation. In the easterly-to-westerly transition phase at 30 hPa, the mesoscale gravity wave forcing is found to be smaller than the resolved wave forcing, whereas the gravity wave forcing dominates over the resolved wave forcing in the opposite phase. Finally, we discuss the uncertainties in the wave forcing estimates using the reanalyses.http://www.atmos-chem-phys.net/15/6577/2015/acp-15-6577-2015.pdf |
| spellingShingle | Y.-H. Kim H.-Y. Chun Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses Atmospheric Chemistry and Physics |
| title | Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses |
| title_full | Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses |
| title_fullStr | Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses |
| title_full_unstemmed | Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses |
| title_short | Momentum forcing of the quasi-biennial oscillation by equatorial waves in recent reanalyses |
| title_sort | momentum forcing of the quasi biennial oscillation by equatorial waves in recent reanalyses |
| url | http://www.atmos-chem-phys.net/15/6577/2015/acp-15-6577-2015.pdf |
| work_keys_str_mv | AT yhkim momentumforcingofthequasibiennialoscillationbyequatorialwavesinrecentreanalyses AT hychun momentumforcingofthequasibiennialoscillationbyequatorialwavesinrecentreanalyses |