Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2015, Vol. 12, No. 4, pp. 133-142
Diagnosis of ice nuclei in the clouds by the device SEVIRI
V.V. Chukin
1 , I.N. Melnikova
1 , T.T. Nguyen
1 , V.N. Nikulin
1 , A.F. Sadykova
1 , A.M. Chukina
1 1 Russian State Hydrometeorological University, Saint-Petersburg, Russia
Information on the type and concentration of ice nuclei in clouds is required to improve the accuracy of clouds evolution and precipitation prediction. The paper considers the developed algorithms for determining the optical thickness and phase state of the clouds, parameters of ice nuclei in the clouds by SEVIRI data. Image processing consists of several stages. The first stage is recognition of cloud pixels and analyzing the data only for the selected pixels. Recognition algorithm accuracy is 77%. At the second stage, cloud optical thickness, liquid and ice water path, as well as phase state of the clouds are determined. Final third stage of the processing is estimating the properties of crystallizing ice nuclei from the temperature at the upper boundary of the clouds and the phase state of the clouds. The results of testing of the algorithms are presented. A series of laboratory experiments to measure the properties of natural ice nuclei were carried out for the interpretation of the satellite data. For this purpose, we used the settings LINC which allows determining the temperature of crystallization of various insoluble particles in the immersion mode of crystallization. Average values of the specific linear energy of water-ice transition of ice nuclei - kaolinite particles (18 pJ/m) and quartz particles (20 pJ/m) were estimated. The algorithms enable remote diagnostics of ice nuclei in the clouds and thereby obtaining information on the potential for the development of precipitation processes. Additional information on the phase state of the clouds can be useful in operational monitoring of aircraft icing zones.
Keywords: cloud optical depth, liquid water path, ice water path, cloud phase state, .supercooled waer droplets freezing, ice nuclei, device SEVIRI
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