Abstract:
Rayleigh lidar observations of temperature structure and gravity wave activity were carried out at Gadanki (13.5° N, 79.2° E) during January–February 2006. A major stratospheric warming event occurred at high latitude during the end of January and early February. There was a sudden enhancement in the stratopause temperature over Gadanki coinciding with the date of onset of the major stratospheric warming event which occurred at high latitudes. The temperature enhancement persisted even after the end of the high latitude major warming event. During the same time, the UKMO (United Kingdom Meteorological Office) zonal mean temperature showed a similar warming episode at 10° N and cooling episode at 60° N around the region of stratopause. This could be due to ascending (descending) motions at high (low) latitudes above the critical level of planetary waves, where there was no planetary wave flux. The time variation of the gravity wave potential energy computed from the temperature perturbations over Gadanki shows variabilities at planetary wave periods, suggesting a non-linear interaction between gravity waves and planetary waves. The space-time analysis of UKMO temperature data at high and low latitudes shows the presence of similar periodicities of planetary wave of zonal wavenumber 1.
