engleski

Application of Meteosat SEVIRI channel differences 0.6-1.6 and 0.6-3.9 micron in convective cells detection

One of the most challenging tasks in the operational nowcasting is the early detection of potentially dangerous convective clouds. Convective cells detecting algorithms, used in the operational weather services, are frequently based on single infra-red channel data. The main advantage of such methods is their applicability during both day and night. However, due to the fact that the criteria in these methods are only cloud-top temperatures and the shape of the clouds, they have proven to be unsuccessful in many cases. Taking into account the properties of solar channels, giving insight into the optical depth of clouds and enabling the differentiation of cloud phase and particle size, an attempt has been made to introduce the data from Meteosat SEVIRI channels 0.6 , 1.6 and 3.9 μm in the automatic convective cell detection. In order to utilize properties of two channels at the same time, and to rule out the clouds which are not of the interest, difference of reflectance in 0.6 and 1.6 μm as well as 0.6 and 3.9 μm channel is used. The differences of reflectance values were calculated for numerous cases and the results were compared to radar reflectivity data. The comparison shows that the differences show small developing cells almost at the same time they are seen by the radar, provided that a proper threshold is set for the difference values. It has also been shown that all potentially dangerous cells are detected which means operationally applicable result and enables the early detection of convective cells in the areas not covered by the radar measurements.

channel differences; convection

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