UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-22 1:34
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Conference: Bucharest University Faculty of Physics 2007 Meeting


Section: Atmosphere and Earth Science; Environment Protection


Title:
Verification of the 98-d hail detection algorithm on Moldavia region


Authors:
Diana Corina Bostan, Adrian Timofte


Affiliation:
National Administration of Meteorology Bucharest, RFC Bacau, SRPV Bacau, Cuza Voda Street, No. 1, Bacau, Romania


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Keywords:


Abstract:
At the beginning of 2004, meteorological radar network of Romania was totally modernized. The meteorological radar network has five radars in S band and three radars in C band. All eight operational radars concur with data to accomplish the national radar mosaic, which generate at every ten minutes at headquarter of National Administration of Meteorology. Severe phenomena did not avoid Romania during last years. We had numerous severe phenomena, and flush floods. Although we were helped by modern technologies and the population was alerted in time, the loss was big. This work paper submits to verify the Hail Detection Algorithm (HDA) for Doppler radar WSR 98- D situated in Barnova, Iasi County, Romania. The studied region is Moldavia, Romania. The Hail Detection Algorithm (HDA) has been designed to look for high reflectivities above the freezing level. Input of the 0oC and -20oC altitudes at the ORPG HCI or UCP from a recent representative sounding can greatly improve algorithm output. The algorithm is designed to work independent of cell type, tilt, and overhang. The primary product produced by the algorithm is Hail Index (HI - Product ID #59) which can be useful in identifying cells that have the potential to produce hail. The Hail Detection Algorithm searches for high values of reflectivity above the freezing level. The reflectivities used are the maximum reflectivities of cell components above the freezing level. For the calculation of the POH, the location of the highest reflectivity of at least 45 dBZ above the freezing level is found. The greater the height above the freezing level, the greater the POH. In the calculation of POSH and MEHS, reflectivities greater than 40 dBZ which exist above the freezing level are used. In addition, a weighting factor is used, such that the greater the reflectivity above 40 dBZ, and the higher the altitude at which this reflectivity exists, the greater the weighting factor used. Reflectivities greater than 50 dBZ, and higher than the altitude of the -20oC isotherm, carry the most weight. This illustrates the need for users to update the altitude of the 0oC and -20oC levels regularly, especially when significant change to the atmosphere is experienced near the radar coverage area. We want to analyse and compare severe hail cases reported in land and the output data of Hail Detection Algorithm (HDA). We will use archived data from 2004, 2005 and 2006; these data will be compared with output data of Hail Detection Algorithm (HDA) and VIL (Vertical Integrated Liquid) for each severe storm founded.