Waterspout cloud top detection using MSG SEVIRI infrared brightness temperature over the northern Ionian Sea, Greece

Abstract

Abstract. Waterspouts pose a significant threat for coastal areas, maritime activities and structures and thus their study is essential. They are frequently occurring in the Mediterranean Sea and particularly in the northern coasts. A vulnerable area of waterspout formation is the Ionian Sea according to recent research and especially the water body around Corfu Island, Greece. The Laboratory of Climatology and Atmospheric Environment of the University of Athens has assembled a detailed database of waterspout events, providing additional information such as location and time of these events; valuable information for the methodology followed.In this study, the waterspout data base concerns events from 20 March 2007 to 31 December 2013. Thus, a total of 74 events were recorded and catalogued on 47 days, as there were days with multiple waterspout events. The aim of this study is to investigate the temporal evolution of brightness temperature on tops of waterspout parent clouds that triggered the formation of single or multiple waterspout events, based on the aforementioned database. The cloud top temperature was assessed by using channel at 10.8 µm MSG SEVIRI Level 1.5 Image Data product. The minimum brightness temperature of the cloud top around the waterspout location for four different examined radiuses was estimated during 60 min prior to and after waterspout formation. Results are illustrated in terms of seasonal analysis. During autumn season a decrease of brightness temperature (colder values) was detected at waterspout parent cloud close to waterspout formation.