Retrieval of Temperature Profiles from the MST Radar Backscattered Signal Using Wavelet Decomposition

The vertical profile of temperature for troposphere and lower stratosphere is derived from the backscattered signal received by Indian MST radar located at Gadanki (13.5°N, 79.2° E). The time series data obtained from MST radar is subjected to Wavelet decomposition. Wavelet decomposition helps in improving and deriving the temperature profiles even at severe weather conditions with low SNR. After decomposition, the temporal spectra of vertical wind are derived and the Brunt-Vaisala frequencies are identified. From the measured Brunt-Vaisala frequencies, temperature profile is obtained following Revathy et al. (1996).

The temperature profiles depend on the accuracy of the Doppler profiles. Under stable atmospheric conditions Dopplers can be obtained without much difficulty. If the atmospheric conditions are unstable and large horizontal winds (≥ 40m/s) exist- affects the temporal spectrum of vertical wind velocity, then deriving dopplers become difficult. Revathy et al. (1996) have reported in their paper that their algorithm is not applicable under unstable atmospheric conditions. To overcome the above limitations algorithm based on Wavelet decomposition technique is proposed. Better Doppler profiles are obtained even under severe weather conditions. Better temperature profiles are obtained. The derived temperature profile is compared with temperature profiles of simultaneously launched radiosonde flights at radar site and signal obtained from MST data without applying Wavelet decomposition i.e., noisy signal obtained from MST data.