Satellite observations of middle atmosphere–thermosphere vertical coupling by gravity waves

• Published in: Annales Geophysicae
• Main Authors: Trinh, Quang Thai, Ern, Manfred, Doornbos, Eelco, Preusse, Peter, Riese, Martin
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus 2018
• Subjects: info:eu-repo/classification/ddc/550; Antarc*; Antarctic; Antarctic Peninsula
• Online Access: https://juser.fz-juelich.de/record/844855; https://juser.fz-juelich.de/search?p=id:%22FZJ-2018-02206%22

Atmospheric gravity waves (GWs) are essentialfor the dynamics of the middle atmosphere. Recent stud-ies have shown that these waves are also important for thethermosphere/ionosphere (T/I) system. Via vertical coupling,GWs can significantly influence the mean state of the T/Isystem. However, the penetration of GWs into the T/I sys-tem is not fully understood in modeling as well as obser-vations. In the current study, we analyze the correlation be-tween GW momentum fluxes observed in the middle atmo-sphere (30–90 km) and GW-induced perturbations in the T/I.In the middle atmosphere, GW momentum fluxes are derivedfrom temperature observations of the Sounding of the At-mosphere using Broadband Emission Radiometry (SABER)satellite instrument. In the T/I, GW-induced perturbations arederived from neutral density measured by instruments on theGravity field and Ocean Circulation Explorer (GOCE) andCHAllenging Minisatellite Payload (CHAMP) satellites. Wefind generally positive correlations between horizontal dis-tributions at low altitudes (i.e., below 90 km) and horizontaldistributions of GW-induced density fluctuations in the T/I(at 200 km and above). Two coupling mechanisms are likelyresponsible for these positive correlations: (1) fast GWs gen-erated in the troposphere and lower stratosphere can propa-gate directly to the T/I and (2) primary GWs with their ori-gins in the lower atmosphere dissipate while propagating up-wards and generate secondary GWs, which then penetrateup to the T/I and maintain the spatial patterns of GW dis-tributions in the lower atmosphere. The mountain-wave re-lated hotspot over the Andes and Antarctic Peninsula is foundclearly in observations of all instruments used in our analy-sis. Latitude–longitude variations in the summer midlatitudesare also found in observations of all instruments. These vari-ations and strong positive correlations in the summer midlat-itudes suggest that GWs with origins related to convectionalso propagate up to the T/I. Different processes which likelyinfluence the ...