Atmospheric turbulences over Guwahati and their association with tropospheric dynamics

Abstract

The paper presents an analysis of structure constant parameter (Cn²) over Guwahati (26.2° N, 91.75° E) in relation to tropospheric dynamics involving parameter like potential temperature, specific humidity and temperature. For this purpose three years data (2007 to 2009) of temperature, humidity and pressure obtained from Radio Sonde (RS) operated at Guwahati are utilised for drawing Cn² profiles up to tropopause height. The results show that depending on season, the average variations of Cn² lie between10^-14 to 10^-19 (m^-2/3). The Cn² gradually decreases to reach a minimum at about 10 km and then starts increasing up to tropopause height of 15-16 km. The analysis further demonstrates that its magnitudes are larger in summer up to the 10-12 km height compared to their winter time values but above this altitude, Cn² is larger in winter compared to their summer time counterparts. The paper also highlights that at pre earthquake (EQ) ambiences, this parameter may dip down by two to three orders of magnitude from its average normal range. The seasonal transition features of Cn² with height and its EQ time changes are put to a correlative analysis with the tropospheric dynamics for an explanation.