Absolute momentum fluxes in the stratosphere with GNSS radio occultation data

SCHMIDT, TORSTEN; DE LA TORRE, ALEJANDRO; ALEXANDER, PEDRO

Workshop; OPAC-IROWG; 2022

A previous feasibility study with COSMIC data showedthat triples of radio occultation (RO) temperature data can be used to derive gravitywave (GW) parameters including horizontal wavelengths and thus the verticalflux of horizontal momentum (shortly momentum flux, MF)in the lowerstratosphere (20-40 km). The spatio-temporal arrangement of these triples islimited because at all locations of the single temperature profiles the same GWmust be observed. The limiting values are typical in the order of Δd≤250 km forthe distance and Δt≤15 minutes for the time interval between involvedmeasurements. Appropriate numbers of tripleswere only available from thebeginning of the COSMIC mission when all six satellites were close in orbit (Mayto October 2006). The new COSMIC-2 data from the early phase 2019/2020in combination with Metop and Spire datasince end of 2020 allow a continuation andupdate of this early study with an improved continuousdatabase, i.e., number oftriples. Beside the geometrical constraint the backgroundseparation from the measured temperature profile is challenging. For thisseparation, i.e., the detrending of large-scale processes from the measuredtemperature profile, several methods exist. In this study we use the RO dataitself and in addition ERA5 re-analysis data from ECMWF. Differences betweenboth detrending approaches (datasets) will be discussed and the results will becompared with MF estimations from other satellite missions.