Estimation of meridional temperature gradient profile using Indian MST radar

Abstract

Meridional temperature gradient profile over Gadanki (13.47°N, 79.18°E) for the height range of 4-18 km with vertical resolution of 150 m is derived, assuming geostrophic wind balance in monthly mean zonal wind and hence thermal wind relationship at this latitude. This study is carried out for the year 1996, with monthly averaged wind data obtained from the Indian MST radar common mode observations. It is observed that average meridional temperature gradient is of the order of 0.5°C/555 km in the winter season with maximum value of 1°C/555 km at around 8 km, and in the summer season it is of the order of 1°C/555 km with a maximum value of 1.75°C/555 km in the height range of 8-15 km having another peak at around 17 km. This enhancement, which is consistent with larger vertical shear in zonal wind field, is probably due

to latent heat released in this region after the onset of south-west monsoon. These derived values of meridional temperature gradient are compared with the observed values obtained by using radiosonde temperature data for two stations,

<span style="font-size:14.0pt;line-height:115%; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Visakhapatnam<span style="font-size:14.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN"> and Madras. These values are in good agreement,which prove the validity of the above cited approximation at this latitude.</span></span>