Wave activity in the vicinity of the tropopause, calculated from GPS radio occultation a) temperature and b) potential temperature profiles

A. DE LA TORRE (1), T. SCHMIDT (2), J. WICKERT (2), P. ALEXANDER (1) AND P. LLAMEDO (1)

Viena, Austria

Congreso; EGU 2007; 2007

EGU

Previous wave activity (WA) global analysis from GPS radio occultation (RO) temperature data profiles (e.g. Venkat Ratnam et al, 2004, Randel and Wu, 2005, de la Torre et al, 2006) appear as a promising tool in the understanding of the transfer of momentum and energy between the troposphere and the stratosphere. It is well known that this method includes several assumptions (e.g. small departures from spherical symmetry) and restrictions (e.g. refraction effects due to background winds and limited vertical and horizontal resolution). Any wave analysis, must deal with the morphology of T profiles and their abrupt discontinuities in their vertical derivatives near the tropopause/s, mainly at equatorial regions. This feature prevented us in previous works to analyze wave structures from RO data in the lower and middle atmospheres including the tropopause too. We imposed an upper cutoff equal to 10 km for the observable vertical wavelengths. As a consequence, important WA contributions as those expected from planetary, mountain and convection waves were systematically excluded. We now discuss the possible benefit of calculating relative variances and potential wave energy near to the tropopause, by band-pass filtering simulated and real temperature and potential temperature profiles, taking into account the less abrupt character of this last parameter. Real T profiles are taken from RO events.