Seasonal, annual and inter-annual features of turbulence parameters over the tropical station Pune (18°32' N, 73°51' E) observed with UHF wind profiler

摘要

The present study is specifically focused on the seasonal, annual and inter-annual variations of the refractive index structure parameter (C_n~2) using three years of radar observations. Energy dissipation rates (ε) during different seasons for a particular year are also computed over a tropical station, Pune. Doppler spectral width measurements made by the Wind Profiler, under various atmospheric conditions, are utilized to estimate the turbulence parameters. The refractive index structure parameter varies from 10~(17.5) to 10~(-13)m~(-2/3) under clear air to precipitation conditions in the height region of 1.05 to 10.35 km. During the monsoon months, observed C_n~2 values are up to 1-2 orders of magnitude higher than those during pre-monsoon and post-monsoon seasons. Spectral width correction for various non-turbulent spectral broadenings such as beam broadening and shear broadening are made in the observed spectral width for reliable estimation of ε under non-precipitating conditions. It is found that in the lower tropospheric height region, values of ε are in the range of 10~(-6) to 10~(-3) m~2 s~(-3). In summer and monsoon seasons the observed values of s are larger than those in post-monsoon and winter seasons in the lower troposphere. A comparison of C_n~2 observed with the wind profiler and that estimated using Radio Sonde/Radio Wind (RS/RW) data of nearby Met station Chikalthana has been made for the month of July 2003.