Verification of an algorithm (DWSR 2500C) for hail detection (original) (raw)
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Meteorological Applications
This study investigated the radar-derived parameters in hail-producing storms and compared two hail-detection approaches in order to select the optimal method for real-time hail detection for the southern part of Romania. A statistical analysis of radar parameters was made, and the thresholds for radar-deriver parameters in hailproducing storms were determined. In addition, the hail storms' life cycle and diurnal and seasonal cycles of hail occurrence were investigated. The first algorithm developed in this study was based on the logistic regression model (LRM); the second one on the vertically integrated liquid (VIL) density algorithm. These algorithms were tested for the convective seasons (May-September) of 2014 and 2015. For the construction of the LRM, the composite reflectivity (CR), VIL and echo-top high (ET) were used as predictors for the probability of hail occurrence determination for 43 hail events observed at the synoptic station located in the radar-coverage area. The obtained statistics showed a marked diurnal cycle of hail occurrence with a maximum in the afternoon hours (1500-1800 LT), and the highest occurrence frequency of hail falls was in June. The results revealed that 93% of hail events occurred with 60 dBZ CR, 87% with 13 km ET, 100% with 55 kg/m 2 VIL and 100% with 4.5 g/m 3 VIL density. For the two hail-detection methods' performance comparison, a twoby-two contingency table was constructed and several statistical scores calculated. The LRM algorithm performed better than the VIL density algorithm.
Development and behaviour of a radar-based operational tool for hailstorms identification
Atmospheric Research, 2007
Hailstorms are a common meteorological phenomenon in Spain which causes substantial economic damage especially in spring and summer. During 2000 and 2001, a radar-based application for convective monitoring was developed at STAP (Forecasting and Analysis Techniques Department); in order to improve this nowcasting tool, it is needed to include an advanced procedure to estimate the presence of hail as a complementary module in the operational application. A preliminary study, carried out during 2001, showed that the Waldvogel technique, VIL (vertical integrated liquid) density and the hail detection algorithm (HDA) are the methodologies which proved more accurate in our latitudes.
Environmental & Socio-economic Studies
Hail involving very large hailstones (maximum diameter ≥ 5 cm), is a rare but very hazardous phenomenon in Poland, and can be forecast using reflectivity signatures. Every year, Poland experiences from one to over a dozen storms with such large hailstones. Despite the current recommendations regarding polarimetric techniques used in hail risk monitoring, Poland does not have a fully polarimetric radar network. Therefore it is essential to check hail detection capabilities using only reflectivity techniques based on individual radar systems involving hail detection algorithms such as Waldvogel et al. (1979) or Vertically Integrated Liquid thresholds connected with manual signature analysis to get better warning decisions. This study is aimed to determine the reflectivity features, thresholds and lead times for nowcasting of severe storms with very large hailstones in Poland, using data from the Polish radar system and from the European Severe Weather Database for the period 2007–2015...
Atmospheric Research, 2009
In order to identify hail into thunderstorms identified with radar data, different kinds of techniques are use based. This paper will evaluate some of these methodologies for the case of the Ebro valley (NE Spain), in order to obtain the best method to identify hail at surface. To achieve this end, an analysis of the 2004 and 2005 hail seasons has been undertaken using C-band radar, MM5 meteorological model outputs and ground observations provided by two hailpad networks. These data were integrated, identifying, characterizing and tracking the convective cells, and obtaining for each one different hail probability equations by means of various radar techniques. Kinetic energy flux was found to be the best parameter for distinguishing between hail and no-hail precipitation, although there was found to exist no significant difference between the various methods used. Moreover, the high correlations between radar parameters obtained by means of cell analyses led us to reduce the initial number of variables in new radar parameters. These new variables are defined and provide new improved models of the intensity of the storm.
A comparison of multi-sensor hail diagnosis techniques
21st Conference on …, 2005
Stumpf et al (2004) summarize many operational and experimental techniques for diagnosing the presence of large hail using a combination of radar reflectivity, reflectivity derivatives, and environmental information. This manuscript represents an initial effort to compare the ...
Assessment of Reliability and Comparison of Two Algorithms for Hail Hazard Detection from Aircraft
Vìsnik Nacìonalʹnogo avìacìjnogo unìversitetu, 2005
This paper presents and analyzes two algorithms for the detection of hail zones in clouds and precipitation: parametric algorithm and adaptive non-parametric algorithm. Reliability of detection of radar signals from hailstones is investigated by statistical simulation with application of experimental researches as initial data. The results demonstrate the limits of both algorithms as well as higher viability of non-parametric algorithm. Polarimetric algorithms are useful for the implementation in ground-based and airborne weather radars.