INSTABILITY INDICES AS AN INDICATOR OF THUNDERSTORMS IN EASTERN BULGARIA - PRELIMINARY RESULTS

Bulgarian Geophysical Journal, 2012, Vol. 38, DOI: https://doi.org/10.34975/bgj-2011.37.2
B. Markova, R. Mitzeva

Abstract:
The work is directed to test the ability of some instability indices to be used as an indicator of lightning from convective clouds. Three instability indices (CAPE, Lifted Index and K Index) are calculated using environmental conditions of 98 days with precipitation, detected in eleven synoptic stations located in eastern Bulgaria in the period April – September 2006. For the statistical analyses the cases have been divided in two samples – ordinary precipitating clouds and thunderstorms. The results reveal that the distributions of the studied indices are significantly different in the both samples. The critical values (thresholds) of the three instability indices that may separate the studied cases into two groups (ordinary clouds and thunderstorms) are established. The best discrimination between thunderstorms and ordinary precipitating clouds is obtained using the threshold values of Lifted index. The performed multiple discriminant analysis shows that the classification function obtained by combination of instability indices does not improve the skill to predict the occurrence of thunderstorms in comparison to the single use of Lifted index.

Keywords:
Instability indices, thunderstorms, discriminant analyses

Author information:
Author: B. Markova
E-mail: b_markova@abv.bg 
Affiliation: National Institute of Meteorology and Hydrology –Varna, Department Weather Forcast, 10 Sv. Nikola mst., 9010 Varna, Bulgaria

Author: Rumiana Mitzeva
E-mail: rumypm@phys.uni-sofia.bg 
Affiliation: Sofia University, Faculty of Physics, Department of Meteorology and Geophysics, 5 James Boucher Blvd., 1164 Sofia, Bulgaria

How to cite:
Markova, B., & Mitzeva, R. (2012). INSTABILITY INDICES AS AN INDICATOR OF THUNDERSTORMS IN EASTERN BULGARIA – PRELIMINARY RESULTS. Bulgarian Geophysical Journal, Vol. 38, p. 12-20. https://doi.org/10.34975/BGJ-2012.38.2