IANIGLA   20881
INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Estimating the probability of convection events from statistical analysis of temperature and humidity vertical profiles, shear and helicity
Autor/es:
ARANEO D.; SIMONELLI S.; NORTE F.; SANTOS R.; BUSTOS C.
Lugar:
Helsinki
Reunión:
Conferencia; 7th European Conference on Severe Storms; 2013
Institución organizadora:
European Severe Storms Laboratory
Resumen:
The objective of this work is to determine the vertical profile patterns of temperature (T) and dew point (Td) for the Northern of Mendoza Province and to obtain a statistical forecast model of convection using these profiles as predictors. Rawinsondes at 12 UTC from Mendoza-Aero weather station (National Weather Service) were used in order to obtain the profiles and to adjust the forecast model. Several 1987-2005 October-March periods were used for the analysis and the 2006-2010 November-March periods were used to validate the predictions. We defined a Convection Occurrence Index (C) according to the reported observations during 24 hours, starting at 9 UTC before the rawinsonde observation. The Principal Component Analysis (PCA) was applied in order to determine the vertical profiles patterns of T and Td. In order to build the forecast model, the resulting component loadings were used as predictors in a logistic multiple-regression fit with the C index as response variable. The helicity and 850-400 hPa shear were also incorporated as predictors in the logistic multiple-regression fit. The PCA resulted useful to obtain the vertical profile patterns of T and Td. The resulting patterns in direct and reverse modes represent real cases. The analysis of T and Td sheds 6 significant components explaining 92% of the system variability. In the studied cases, over than 70% of the forecast model effectiveness is obtained using only the T and Td profiles (similar to that found in other studies by traditional indices). The effectiveness could be improved by changing the definition of C and the incorporation of shear and helicity as predictors. Profile patterns of T and Td reveals that the probability of convection increases (decreases) with strong (weak) T lapse-rate between low and middle levels of the troposphere and high (low) moisture content in the lower layers.
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