Long-term observations of gravity wave activity in the lower stratosphere with GPS radio occultation data

SCHMIDT, T.; DE LA TORRE, A.; LLAMEDO, P.; ALEXANDER, P.; LILIENTHAL, F.; JACOBI, C.; WICKERT, J.

Congreso; 26thIUGG General Assembly; 2015

Global gravity wave (GW) parameters (potential energy and vertical flux of absolute horizontal momentum) are retrieved from GPS radio occultation (RO) data. The RO technique uses GPS signals received aboard low Earth orbiting satellites for atmospheric limb sounding. Atmospheric temperature profiles are derived with high vertical resolution whereas the GPS RO technique is sensitive to GWs with small ratios of vertical to horizontal wavelengths. Since 2006 the six-satellite U.S./Taiwan FORMOSAT-3/COSMIC mission delivers about 2000 global distributed radio occultations daily. This gives the possibility for the determination of absolute momentum flux (MF) as the most important parameter for the quantification of GW activity. In this presentation we discuss MF distributions in the lower stratosphere derived from closely spatio-temporal RO temperature fluctuation profiles. The results for different seasons are compared with other MF climatologies (e.g. SABER) and limitations of the method will be addressed. In addition to MF the variability of potential energy derived from several RO missions since 2001 will be discussed.