A Comparison of Methods for Determining Tropopause Height from VHF Radar Observations

Abstract

Four methods of estimating the height of the tropopause with VHF radar are compared and evaluated using data from a wind-profiling radar located at Platteville, Colorado, approximately 50 km north of Denver. An empirically derived method determines the tropopause height from the strength and persistence of the reflections. A second, theoretically based, method uses Fresnel scattering model estimates of the temperature gradient to determine the tropopause height. A third method identifies specular reflections associated with the tropopause by comparing vertical with oblique reflections. The final method combines the theoretically based method with a consensus set method for determining the most consistent estimates. The methods are compared by taking differences between the estimates and the tropopause heights determined from radiosonde data using the WMO definition of the tropopause. Each method is evaluated by calculating rms differences from the radiosonde determinations and by the number of differences that exceed an acceptable magnitude.