Validação da técnica de Waldvogel para prognóstico de ocorrência de granizo no interior paulista
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2019-12-09
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Universidade Estadual Paulista (Unesp)
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A geração de alertas de ocorrência de granizo é importante para a diminuição dos danos gerados pelo fenômeno, visto que é a segunda maior causa de prejuízos na agricultura no Brasil, com perda de R$ 1 bilhão entre 2006 e 2017. São Paulo é o terceiro estado com maior prejuízo, correspondendo a cifra de R$ 172 milhões. Com a finalidade de aprimorar as elaborações de alertas de granizo, direcionados aos produtores agrícolas, defesa civil e a comunidade em geral, o objetivo deste trabalho é validar a técnica de Waldvogel, o qual utiliza dados de radar meteorológico e sondagem atmosférica: a técnica fundamenta-se na diferença (∆H) entre a altura máxima da refletividade de 45 dBZ (H45), obtida do radar meteorológico, e a altura do nível de congelamento (H0), obtida da sondagem atmosférica. Foram utilizados 175 casos comprovados de granizo, que atingiram a superfície, na área de cobertura do radar meteorológico de Bauru/SP, durante a estação chuvosa entre os anos de 2008 e 2018. Neste período 3/4 dos eventos ocorreram no período chuvoso, entre os meses de outubro e março, e 1/4 no período seco entre os meses de abril e setembro. Diferentemente do resultado encontrado por Waldvogel, na região central da Europa, que atesta que a partir de ∆H ≥ 1,4 km ocorre granizo nas tempestades, os resultados encontrados no interior do estado de São Paulo, certificam que a partir de ∆H ≥ 0,28 km, ocorrem precipitações de granizo nas tempestades.
The generation of hail warnings is important to reduce the damage generated by the phenomenon, as it is the second largest cause of damage to agriculture in Brazil, with loss of R$ 1 billion between 2006 and 2017. São Paulo is the third state with the largest loss, corresponding to R$ 172 million. In order to improve the studies to elaborate hail alerts directed to agricultural producers, civil defense and the community in general, the objective of this work was to validate the Waldvogel technique, which uses meteorological radar data and atmospheric survey: the technique is based on the difference (∆H) between the maximum reflectivity height of 45 dBZ (H45) obtained from the weather radar, and the height of the freezing level (H0) of the atmospheric sounding. We used 175 proven cases of hail, that hit the surface, in the coverage area of the weather radar of Bauru/SP, during the rainy season between 2008 and 2018. In this period 3/4 of the events occurred in the rainy season, between october and march, and 1/4 in the dry season between april and september. Unlike the results found by Waldvogel in central Europe, which attests that from ∆H ≥ 1.4 km there is hail in thunderstorms, the results found in the interior of the state of São Paulo, certify that from ∆H ≥ 0.28 km occurs hail during the storms.
The generation of hail warnings is important to reduce the damage generated by the phenomenon, as it is the second largest cause of damage to agriculture in Brazil, with loss of R$ 1 billion between 2006 and 2017. São Paulo is the third state with the largest loss, corresponding to R$ 172 million. In order to improve the studies to elaborate hail alerts directed to agricultural producers, civil defense and the community in general, the objective of this work was to validate the Waldvogel technique, which uses meteorological radar data and atmospheric survey: the technique is based on the difference (∆H) between the maximum reflectivity height of 45 dBZ (H45) obtained from the weather radar, and the height of the freezing level (H0) of the atmospheric sounding. We used 175 proven cases of hail, that hit the surface, in the coverage area of the weather radar of Bauru/SP, during the rainy season between 2008 and 2018. In this period 3/4 of the events occurred in the rainy season, between october and march, and 1/4 in the dry season between april and september. Unlike the results found by Waldvogel in central Europe, which attests that from ∆H ≥ 1.4 km there is hail in thunderstorms, the results found in the interior of the state of São Paulo, certify that from ∆H ≥ 0.28 km occurs hail during the storms.
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Granizo, Tempestades, Radar Meteorológico, Hail, Storms, Weather Radar