Atmospheric turbulences over Guwahati and their association with tropospheric dynamics

Abstract

<span style="letter-spacing:-.1pt;mso-fareast-language: AS;mso-bidi-language:AS" lang="EN-GB">The paper presents an analysis of structure constant parameter (Cn²) over Guwahati (26.2°N, 91.75°E<span style="letter-spacing:-.1pt;mso-fareast-language:AS;mso-bidi-language:AS" lang="EN-GB">) in relation to tropospheric dynamics involving atmospheric variabilities, like temperature, potential temperature and specific humidity. Data collected from radiosonde operated at Guwahati are utilised for drawing seasonal profiles of Cn² up to the tropopause height. The results show that depending on season, the average values of Cn² may vary between 10^-14.5 and 10^-19 m^-2/3 and that their magnitude decreases gradually to reach a minimum of -18.3 m^-2/3at around 10 km and then starts increasing up to the tropopause height of 15-16 km. The analysis, further, demonstrates that Cn² value reaches maximum in summer and minimum in winter, within the height range of 1-10 km. Bu<span style="letter-spacing:-.1pt;mso-ansi-language:EN-SG;mso-fareast-language: AS;mso-bidi-language:AS" lang="EN-SG">t beyond the altitude of 10 km, Cn² shows higher values in winter as compared to its summer time counterparts. <span style="letter-spacing:-.1pt;mso-fareast-language:AS;mso-bidi-language: AS" lang="EN-GB">The paper also highlights that at pre earthquake (EQ) ambiences, <span style="letter-spacing:-.1pt;mso-ansi-language:EN-SG;mso-fareast-language: AS;mso-bidi-language:AS" lang="EN-SG">this parameter<span style="letter-spacing:-.1pt;mso-fareast-language:AS;mso-bidi-language:AS" lang="EN-GB"> may dip down by two to three orders of magnitude from its average normal range. The seasonal transition pattern of Cn²with height and the EQ time changes in Cn² features are put to a correlative analysis with the tropospheric dynamics for an explanation.

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