The calculation of gravity waves global stratospheric net momentum flux and drag from one year of COSMIC-2, Spire and METOP radio occultations

ALEXANDER, P.; DE LA TORRE, A.; SCHMIDT, T.

Taipei

Congreso; Taiwan International Assembly of Space Science, Technology, and Industry; 2023

Taiwan Space Agency

Gravity waves (GW) transport momentum flux (MF) andenergy across the atmosphere. The dissipation of these waves may produce forceson the atmospheric flow known as drag, which can affect weather as well as climate. Global Positioning System(GPS) radio occultation (RO) is one of the measuring techniques used onboardsatellites to provide vertical temperature soundings with global and permanentcoverage. These profiles may be applied in the study of GW. Some usual analysismethods provide absolute GWMF, but are missing its net direction. This happensbecause the procedures cannot deduce the propagation sense of GW and hence thedirection of MF. We apply here a method that allows the net calculation withfour nearly collocated RO retrievals (quartets). We use about 10,000 daily profilesfrom March 1, 2022 to February 28, 2023 to study the seasonal and latitudinalglobal characteristics of net GWMF in the height interval from 20 to 35 km.About 600 quartets were found. The calculated zonal MF and drag exhibitednegative minima at middle and high latitudes during winter in the SouthernHemisphere. This characteristic is usually assigned to orographic sources. Asimilar intensity in zonal MF and drag is found during the same season at lowlatitudes. Meridional components are less significant. The increase ofsatellite observations in the last years due to the release of new missions ledto a high spatial and temporal density of profiles that now allows theattainment of net GWMF climatologies over a seasonal time scale and a few 1000 kmwide latitude bands. This performance may be even improved if there is a futureincrement of retrievals.