The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalyses
<p>The quasi-biennial oscillation (QBO) of the stratospheric tropical winds influences the global circulation over a wide range of latitudes and altitudes. Although it has strong effects on surface weather and climate, climate models have great difficulties in simulating a realistic QBO, espec...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/9549/2023/acp-23-9549-2023.pdf |
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| author | M. Ern M. A. Diallo D. Khordakova I. Krisch P. Preusse O. Reitebuch J. Ungermann M. Riese |
| author_facet | M. Ern M. A. Diallo D. Khordakova I. Krisch P. Preusse O. Reitebuch J. Ungermann M. Riese |
| author_sort | M. Ern |
| collection | DOAJ |
| description | <p>The quasi-biennial oscillation (QBO) of the stratospheric tropical winds
influences the global circulation over a wide range of latitudes and altitudes.
Although it has strong effects on surface weather and climate, climate models
have great difficulties in simulating a realistic QBO, especially in the lower stratosphere.
Therefore, global wind observations in the tropical upper troposphere
and lower stratosphere (UTLS) are of particular interest for
investigating the QBO and the tropical waves
that contribute significantly to its driving.
In our work, we focus on the years 2018–2022 and
investigate the QBO and different
tropical wave modes in the UTLS region using global
wind observations made by the Aeolus satellite instrument and three meteorological reanalyses: the fifth generation European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-5), the Japanese 55-year Reanalysis (JRA-55)
of the Japan Meteorological Agency (JMA), and the
Modern-Era Retrospective Analysis for Research and Applications, version 2
(MERRA-2).
Further, we compare these data with observations of selected radiosonde
stations.
By comparison with Aeolus observations, we find that, on zonal average, the QBO in the lower stratosphere is well represented in all three reanalyses,
with ERA-5 performing best.
Averaged over the years 2018–2022, agreement between Aeolus and the reanalyses
is better than 1 to 2 <span class="inline-formula">m</span> <span class="inline-formula">s</span><span class="inline-formula"><sup>−1</sup></span>, with somewhat larger
differences during some periods.
Differently from zonal averages, radiosonde stations provide only local observations and are therefore biased by global-scale
tropical waves, which limits their use as a QBO standard.
While reanalyses perform well on zonal average, there can be considerable
local biases between reanalyses and radiosondes.
We also find that, in the tropical UTLS, zonal wind variances of
stationary waves and the most prominent global-scale traveling
equatorial wave modes, such as Kelvin waves, Rossby-gravity waves, and
equatorial Rossby waves, are in good agreement
between Aeolus and all three reanalyses
(in most cases better than 20 % of the peak values in the UTLS).
On zonal average, this supports the use of reanalyses as a reference
for comparison with free-running climate models,
while locally, certain biases exist, particularly in the QBO wind shear zones and around the 2019–2020 QBO disruption.</p> |
| first_indexed | 2024-03-12T12:30:20Z |
| format | Article |
| id | doaj.art-158d88747fc641c68e031fe9e5c8a6a7 |
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| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-03-12T12:30:20Z |
| publishDate | 2023-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-158d88747fc641c68e031fe9e5c8a6a72023-08-29T10:44:09ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242023-08-01239549958310.5194/acp-23-9549-2023The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalysesM. Ern0M. A. Diallo1D. Khordakova2I. Krisch3P. Preusse4O. Reitebuch5J. Ungermann6M. Riese7Institut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH, Jülich, GermanyInstitut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH, Jülich, GermanyInstitut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH, Jülich, GermanyDeutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, GermanyInstitut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH, Jülich, GermanyDeutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, GermanyInstitut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH, Jülich, GermanyInstitut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH, Jülich, Germany<p>The quasi-biennial oscillation (QBO) of the stratospheric tropical winds influences the global circulation over a wide range of latitudes and altitudes. Although it has strong effects on surface weather and climate, climate models have great difficulties in simulating a realistic QBO, especially in the lower stratosphere. Therefore, global wind observations in the tropical upper troposphere and lower stratosphere (UTLS) are of particular interest for investigating the QBO and the tropical waves that contribute significantly to its driving. In our work, we focus on the years 2018–2022 and investigate the QBO and different tropical wave modes in the UTLS region using global wind observations made by the Aeolus satellite instrument and three meteorological reanalyses: the fifth generation European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-5), the Japanese 55-year Reanalysis (JRA-55) of the Japan Meteorological Agency (JMA), and the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). Further, we compare these data with observations of selected radiosonde stations. By comparison with Aeolus observations, we find that, on zonal average, the QBO in the lower stratosphere is well represented in all three reanalyses, with ERA-5 performing best. Averaged over the years 2018–2022, agreement between Aeolus and the reanalyses is better than 1 to 2 <span class="inline-formula">m</span> <span class="inline-formula">s</span><span class="inline-formula"><sup>−1</sup></span>, with somewhat larger differences during some periods. Differently from zonal averages, radiosonde stations provide only local observations and are therefore biased by global-scale tropical waves, which limits their use as a QBO standard. While reanalyses perform well on zonal average, there can be considerable local biases between reanalyses and radiosondes. We also find that, in the tropical UTLS, zonal wind variances of stationary waves and the most prominent global-scale traveling equatorial wave modes, such as Kelvin waves, Rossby-gravity waves, and equatorial Rossby waves, are in good agreement between Aeolus and all three reanalyses (in most cases better than 20 % of the peak values in the UTLS). On zonal average, this supports the use of reanalyses as a reference for comparison with free-running climate models, while locally, certain biases exist, particularly in the QBO wind shear zones and around the 2019–2020 QBO disruption.</p>https://acp.copernicus.org/articles/23/9549/2023/acp-23-9549-2023.pdf |
| spellingShingle | M. Ern M. A. Diallo D. Khordakova I. Krisch P. Preusse O. Reitebuch J. Ungermann M. Riese The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalyses Atmospheric Chemistry and Physics |
| title | The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalyses |
| title_full | The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalyses |
| title_fullStr | The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalyses |
| title_full_unstemmed | The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalyses |
| title_short | The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalyses |
| title_sort | quasi biennial oscillation qbo and global scale tropical waves in aeolus wind observations radiosonde data and reanalyses |
| url | https://acp.copernicus.org/articles/23/9549/2023/acp-23-9549-2023.pdf |
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