Large-scale dynamic and composition disturbances in the mesosphere region caused by transient planetary waves: 2-D: Modelling and liars data analysis

Abstract

Temperature LIARS data (ISAMS instrument) from 100 mb to mesospheric levels jointly with ozone data (MLS instrument), UKMO assimilated data, results of radio absorbtion measurements and meteoradar neutral wind data over Bulgaria were used to study the character periods and wave numbers of transient planetary waves in the middle atmosphere in spring 1992 (centered in May 1992) with a special attention to waves intensity at high levels. Due to rather short temporal intervals of continuous measurements by ISAMS and MLS instruments MEM spectral teknique was used for statistical analysis. The results of data analysis has revealed different character periods of oscillations like these : 2–3, 5–7, 9–15 days which exist also in the mesosphere. It is interesting to make a focus to the wave with 2–3 day period which has zonal wave number m=3. Spectral density of temperature data sets for m=1,2,3 from 100 to 0.01 mb was calculated. The existance of transient waves at mesospheric levels permits to suppouse a possibility of its penetration from troposphere. 2-D numerical quasigeostrophic model for planetary waves was used to investigate the possibility of such penetration for May conditions in accordance to the period of ISAMS and MLS measurements. The results of model runs has shown the possibility for transient waves to penetrate from below to higher levels , showing resonant responce of the middle atmosphere similar to results of data analysis.