SABER Observations of Gravity Wave Responses to the Madden‐Julian Oscillation From the Stratosphere to the Lower Thermosphere in Tropics and Extratropics

Abstract

AbstractThe 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.