Reprint 889 Performance of Instability Indices of the Troposphere as Derived from a Ground-based Microwave Radiometer
نویسنده
چکیده
The ground-based microwave radiometer provides a unique opportunity to continuously derive instability indices of the troposphere based on the temperature and humidity profiles. In the present study, three different kinds of instability indices are considered: (a) based on the temperature and dew point values at selected levels only, e.g. K index, (b) based on the energy available for convective development and calculated from the area bound by the temperature profile and the saturated adiabatic lapse rate curve, e.g. CAPE, and (c) based on the curvature of the thermodynamic profile, e.g. shape factor as derived from the vertical gradient of equivalent potential energy. The performance of the various instability indices in the nowcasting of thunderstorms is studied in two springand summer-time periods in Hong Kong. Based on the thunderstorm reports at a manned synoptic weather station in Hong Kong, it is found that K index and CAPE have better indication of the occurrence of thunderstorms. In particular, using a dataset larger than that employed in a previous radiometer study by Chan (2009), the temporally averaged K index has good correlation with the frequency of lightning flashes within a distance of several tens of kilometres from the radiometer.
منابع مشابه
Application of ground-based, multi-channel microwave radiometer in the nowcasting of intense convective weather through instability indices of the atmosphere
A ground-based microwave radiometer gives the possibility of providing continuously available temperature and humidity profiles of the troposphere, from which instability indices of the atmosphere could be derived. This paper studies the possibility of correlating the radiometer-based instability indices with the occurrence of intense convective activity, namely, the occurrence of lightning. Th...
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Thermodynamic and dynamic quantities, such as the K-index and GUSTEX (a wind gust estimate), are commonly used in the nowcasting of intense convective weather. In the past, they were derived from conventional upper-air ascent measurements, which were normally only available twice a day. In the tropics, the thermodynamic property of the troposphere could change rapidly in rain episodes and the c...
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