Identificación y caracterización del granizo mediante el radar ...

AbstractWith the purpose of identifying and characterising hail and improving its riskassesment, a great number of techniques based on troposphere observations have beendeveloped. In general, all these techniques are based on the use of meteorological radar, thismeans that all of them depend on geography and the used radar. These surface hail identificationmethods are described and evaluated in this thesis. Different algorithm and techniqueimprovements are proposed with the aim of improving the results. Moreover, a new maximumexpected surface hail size technique and a proposal for nowcasting convective cell radarparameters are also presented. These forecasts will give the possibility to nowcast theprobability of hail and the maximum expected hail size.Many of these existing hail identification and characterisation methodologies are basedon equations or empirical relationships that need to be study region and used radar custommade.For this reason, this thesis proposes a new technique which has improvements on radaralgorithms, the integration of radar data with mesoscale and thermodynamic information and theuse of boxplots.The 2004 and 2005 Ebro Valley hail events observed during hail campaigns have beenused to achieve these ends. To study these events, the available data during these campaignshave been the C band radar observations, the MM5 mesoscale meteorological outputs and thesurface hail size observations (provided by the University of Leon). All these data have beenintegrated by using the thesis developed software, RHAP, Rainfall events and HailstormsAnalysis Program. After analysing all the selected events, precipitation structures have beenidentified, characterised and tracked obtaining a large number of radar parameters for each one.From these results, hail identification and characterisation techniques have been improved anddeveloped and a methodology to obtain radar parameters nowcasting models has been proposed.Taking into account hail identification, it has been obtained that the kinetic energy fluxis the best parameter for distinguishing between hail of any size and no-hail precipitation in theEbro valley region. Moreover, results have shown non-significant difference between all radarparameters that are correlated with hail precipitation. On the other hand, new study region andused radar custom-made probability of hail equations have been obtained. Moreover, by usingboxplots, it has also been possible to estimate maximum surface hail size with the best results incase of hail the size between 10 and 30 mm. It can be concluded there is no radar parameter thatcan be selected with significance difference as the best parameter for distinguishing betweenhail and no-hail precipitation and for estimating the maximum expected hail size. Due to theseXIII