Lightning activity, rainfall and flash flooding – occasional or interrelated events? A case study in the island of Crete

Abstract

Abstract. The majority of cyclones passing over Crete in late autumn to early winter originate from southwest, west and northwest and are of varying size and intensity. A number of these cyclones cause flash floods. The present study reports the possible relationships between lighting activity and high precipitation related to flash flood events. In this study an attempt was made to correlate the lightning number and location, recorded by the ZEUS lightning detection system, with the rainfall characteristics for sixteen rain events (4 flood and 12 non-flood events) on the island of Crete, during the period [2008][2009]. Spatiotemporal analysis of rain and rain rate with flash count was performed with respect to distance (radius) of flashes from raingauge location at various temporal scales, in order to examine the correlation of accumulated rainfall and lightning activity. The maximum attained statistical significant correlation was obtained within a circular area of an average radius of 15 km around the raingauge, and an average time lag of flash count prior precipitation accumulation of 15 min. The maximum correlation between the lightning and rainfall data is obtained for shorter time lags for the flood events (15 min) than the non-flood events (25 min), that could reflect the faster propagation of flood triggering storms due to high convective activity. Results show increased lightning activity occurring during flood triggering storms, by an average of four times higher. Furthermore, there is evidence that the number of flashes that occur during a precipitation event is related to precipitation depth when the latter is adequate to produce a flood event. Differences between flood and non-flood producing storms need to be further assessed by analyzing more independent parameters, including the synoptic conditions and dominant flash flood hydrological generating processes.

Selection of intense rainfall events based on intensity thresholds and lightning data in Switzerland

“…Our study complements other recent efforts focused on using lightning observations to better understand and predict convective storms and their consequences, for example, flash floods (Price et al, 2011a, b;Koutroulis et al, 2012).…”

“…Petersen and Rutledge, 1998;Rivas Soriano et al, 2001;Rivas Soriano and De Pablo, 2003;Pineda et al, 2007;Barnolas et al, 2008;Tadesse and Anagnostou, 2009;Yair et al, 2010;Koutroulis et al, 2012), we propose to calibrate the threshold parameter I * at every station as a function of the presence or absence of lightning. In Sect.…”

“…The premise is that summer thunderstorms with convective activity are commonly associated with lightning (e.g. Tapia et al, 1998;Rivas Soriano et al, 2001;Rivas Soriano and De Pablo, 2003;Barnolas et al, 2008;Tadesse and Anagnostou, 2009;Yair et al, 2010;Koutroulis et al, 2012). A number of recent studies have demonstrated the connection between intra-cloud and cloudto-ground lightning and convective precipitation using rainfall yield (i.e.…”

“…In associating lightning with storm rainfall, we also considered strikes that occurred up to 20 min before the actual rainfall event began, which captures commonly observed time lags in pre-storm lightning-rainfall correlations (e.g. Grungle and Krider, 2006;Koutroulis et al, 2012).…”

Exploring the ability of current climate information to facilitate local climate services for the water sector

“…More than 40 % of the annual precipitation occurs in the winter months. Average precipitation ranges from 440 mm/year on the eastern part of the island to more than 2000 mm/year on the highland western parts, where orographic effects tend to increase both frequency and intensity of winter precipitation Koutroulis et al 2012).…”