16:00 〜 16:15
[PEM11-21] The 2019 Antarctic Stratospheric Sudden Warming effect on Gravity Wave in the Middle Atmosphere
★Invited Papers
キーワード：stratospheric sudden warming、Gravity wave、Antarctic
A Stratospheric sudden warming (SSW) drastically change the meteorological fields in the middle atmosphere. The polar night jet disappears after an onset of a SSW, and zonal wind becomes weak and occasionally reverses from a westerly wind to an easterly wind. This wind variation suppresses gravity wave (GW) activity.
In late August 2019, an Antarctic stratospheric sudden warming (SSW) occurred. Antarctic SSW events are rare and have occurred only twice in the 21st century (2002 and 2019). Although this 2019 SSW event was classified as a minor warming event, the zero zonal wind layer reached a 40 km altitude. An Antarctic stratospheric sudden warming (SSW) occurred on August 30, 2019, and was a vortex displacement minor warming event. We investigated variations in GW activity before and after this rare Antarctic SSW event using two satellite measurements (AIRS and CIPS) and reanalysis data (GEOS-5 FP). The observations and GEOS-5 FP showed that the GW activity in whole southern high latitudes decreased after the SSW onset, with a weakening of zonal wind. The zonal mean GW activity further decreased coincided with a reversal of the zonal mean zonal wind around September 8. The decline in the zonal mean GW activity was probably caused by wind filtering and polar night jet breaking. The GW activity in the Andes also decreased after the onset, although the westerly wind was 40–60 ms-1 and stronger than the zonal mean one. This decline in GW activity was probably caused by wave saturation.
In late August 2019, an Antarctic stratospheric sudden warming (SSW) occurred. Antarctic SSW events are rare and have occurred only twice in the 21st century (2002 and 2019). Although this 2019 SSW event was classified as a minor warming event, the zero zonal wind layer reached a 40 km altitude. An Antarctic stratospheric sudden warming (SSW) occurred on August 30, 2019, and was a vortex displacement minor warming event. We investigated variations in GW activity before and after this rare Antarctic SSW event using two satellite measurements (AIRS and CIPS) and reanalysis data (GEOS-5 FP). The observations and GEOS-5 FP showed that the GW activity in whole southern high latitudes decreased after the SSW onset, with a weakening of zonal wind. The zonal mean GW activity further decreased coincided with a reversal of the zonal mean zonal wind around September 8. The decline in the zonal mean GW activity was probably caused by wind filtering and polar night jet breaking. The GW activity in the Andes also decreased after the onset, although the westerly wind was 40–60 ms-1 and stronger than the zonal mean one. This decline in GW activity was probably caused by wave saturation.