Analysis of warm season thunderstorms using an object-oriented tracking method based on radar and total lightning data

Abstract

Abstract.Monitoring thunderstorms activity is an essential part of operational weather surveillance given their potential hazards, including lightning, hail, heavy rainfall, strong winds or even tornadoes. This study has two main objectives: firstly, the description of a methodology, based on radar and total lightning data to characterise thunderstorms in real-time; secondly, the application of this methodology to 66 thunderstorms that affected Catalonia (NE Spain) in the summer of 2006. An object-oriented tracking procedure is employed, where different observation data types generate four different types of objects (radar 1-km CAPPI reflectivity composites, radar reflectivity volumetric data, cloud-toground lightning data and intra-cloud lightning data). In the framework proposed, these objects are the building blocks of a higher level object, the thunderstorm.The methodology is demonstrated with a dataset of thunderstorms whose main characteristics, along the complete life cycle of the convective structures (development, maturity and dissipation), are described statistically. The development and dissipation stages present similar durations in most cases examined. On the contrary, the duration of the maturity phase is much more variable and related to the thunderstorm intensity, defined here in terms of lightning flash rate. Most of the activity of IC and CG flashes is registered in the maturity stage. In the development stage little CG flashes are observed (2% to 5%), while for the dissipation phase is possible to observe a few more CG flashes (10% to 15%). Additionally, a selection of thunderstorms is used to examine general life cycle patterns, obtained from the analysis of normalized (with respect to thunderstorm total duration and maximum value Correspondence to: T. Rigo (tomeur@meteo.cat) of variables considered) thunderstorm parameters. Among other findings, the study indicates that the normalized duration of the three stages of thunderstorm life cycle is similar in most thunderstorms, with the longest duration corresponding to the maturity stage (approximately 80% of the total time).

Probing the precipitation life cycle by iterative rain cell tracking

“…[4] Various objective tracking methods have been developed and advanced during the last 2 decades, mainly for the purpose of nowcasting strong convective events like thunderstorms [Rosenfeld, 1987;Dixon and Wiener, 1993;Wilson et al, 1998;Johnson et al, 1998;Handwerker, 2002;Hering et al, 2005;Novo et al, 2013] but also the mean life cycles of the cell size and statistics of tracked rain cells have been studied [Kysnarova and Novak, 2009;Peleg and Morin, 2012;Rigo et al, 2012]. Other tracking methods have been applied not only to radar data but also to other high-resolution observational data sets such as satellite data [Lakshmanan et al, 2009;Feng et al, 2012].…”

Preface: 11th Plinius Conference on Mediterranean Storms

“…Ten presentations (six of which are oral, one solicited) were given at the conference within this topic. Two papers (Atencia et al, 2010;Rigo et al, 2010) were thereafter published in the Plinius-11 NHESS special issue, and another one (Terradellas and Téllez, 2010) in the ADGEO special issue. Atencia et al (2010) present an attempt to improve quantitative precipitation forecasts (QPFs) by blending different sources of information, including both numerical weather prediction (NWP) model outputs and weather radar observations processed to obtain a nowcasting of the rainfall field.…”

“…The authors conclude that the blending technique (especially the spatial one) is a suitable approach to improve the QPF in the first hours of observation. Rigo et al (2010) present a nowcasting tool based on the integration of lightning and radar data, which was developed to help the operational forecasters of the Meteorological Service of Catalonia to make decisions in the surveillance and warning of convective precipitation events. The method employs an object-oriented tracking procedure to identify, characterize and track thunderstorms in real time.…”

Nowcasting

“…This adds value when assigning the elements of severe weather or some sort of severity index, but does not necessarily add value to the identification and tracking of the cells. Rigo et al (2010) used both 2D and 3D radar products and total lightning data to identify and track convective storms. A storm track is defined as a time series of cell positions.…”