The 17‐year SABER‐observed gravity wave (GW) temperature variances reveal significant responses of GWs to the Madden‐Julian Oscillation (MJO) over the middle atmosphere (30–100 km) in tropics and extratropics (45°S to 45°N) for boreal winter. The responses vary significantly with latitude but barely with altitude. From 20°S to 45°N, strong positive anomalies are found for MJO Phases 3–5, while negative anomalies for Phases 7–8. From 45–20°S, these patterns are reversed. The peak‐to‐peak differences (positive‐to‐negative anomalies) are ~6–16% relative to the seasonal mean. Comparison with MJO modulations on tropical convection and polar vortex suggests that GW responses in tropics may result from the modulation of GW source, while responses in northern extratropics may result from the modulation of polar vortex, which in turn modulates GW activities. These results highlight the importance of GWs to imprint the tropical MJO signals vertically to the middle atmosphere and horizontally to extratropical regions.
Using 17 years of Modern‐Era Retrospective analysis for Research and Applications, Version 2 (MERRA‐2) data, significant responses of gravity wave (GW) variances, zonal winds and parameterized GW drag to the Madden‐Julian Oscillation (MJO) are identified globally during boreal winter, and their relations are examined. The relative anomalies of GW variances range from −4% (phase 7) to 8% (phase 4) in tropics, and −20% (phase 1) to 20% (phase 5) in the northern polar region (NPR). The anomalies of zonal winds are from −3–3 m/s and −4–8 m/s in tropics and NPR, respectively. The vertical and latitudinal structures of MJO signals in GW, wind and GW drag show coherent patterns. Further analysis implies that in the NPR, the eastward wind leads to westward momentum flux carried by the GWs. This flux leads to westward drag, which drives that of zonal winds and imprint the MJO signal in GWs to the wind.
more » « less- Award ID(s):
- 1753214
- NSF-PAR ID:
- 10375111
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 48
- Issue:
- 20
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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