Wavelet analysis of 14 years' aerosol lidar observations over Pune, India

Over 700 weekly spaced vertical profiles of aerosol number density have been archived during 14-year period (October 1986 - September 2000) using a bi-static Argon ion lidar system at the Indian Institute of Tropical Meteorology (IITM), Pune (18°43 ′N, 73°51′E, 559 m amsl), India. The time series of monthly mean aerosol distributions in the boundary layer as well as at different altitudes have been subjected to the wavelet power spectral analysis to investigate different characteristic waves present in the data. The concurrent solar radiometric column aerosol optical depth data have also been analyzed. Both the time series exhibited 11-15 (annual) and 22-25 (quasi-biennial) months periodicities at statistically significant level, and their absolute power well matches with the Global Wavelet Spectra after smoothing, which further confirms the existence of such longer periodicities in the data. A brief description of the data series and wavelet transform analysis procedure are presented. Added, the implication of environmental parameters on the long-term trends in the lidar aerosol observations is also presented.