• Bardsley, W. E., 1990: On the maximum observed hailstone size. J. Appl. Meteor., 29, 11851188.

  • Changnon, S. A., Jr., 1971: Note on hailstone size distributions. J. Appl. Meteor., 10, 168170.

  • Cheng, L., and M. English, 1983: A relationship between hailstone concentration and size. J. Atmos. Sci., 40, 204213.

  • Cheng, L., M. English, and R. Wong, 1985: Hailstone size distributions and their relationship to storm thermodynamics. J. Appl. Meteor., 24, 10591068.

    • Search Google Scholar
    • Export Citation
  • Dessens, J., 1995: Severe convective weather in the context of a nighttime global warming. Geophys. Res. Lett., 22, 12411244.

  • Dessens, J., and R. Fraile, 1994: Hailstone size distributions in southwestern France. Atmos. Res., 33, 5773.

  • Dessens, J., R. Fraile, V. Pont, and J. L. Sanchez, 2001: Day-of-the-week variability of hail in southwestern France. Atmos. Res., 59–60, 6376.

    • Search Google Scholar
    • Export Citation
  • Dessens, J., C. Berthet, and J. L. Sanchez, 2007: A point hailfall classification based on hailpad measurements: The ANELFA scale. Atmos. Res., 83, 132139.

    • Search Google Scholar
    • Export Citation
  • Federer, B., and A. Waldvogel, 1975: Hail and raindrop size distributions from a Swiss multicell storm. J. Appl. Meteor., 14, 9197.

  • Federer, B., and A. Waldvogel, 1978: Time-resolved hailstone analyses and radar structure of Swiss storms. Quart. J. Roy. Meteor. Soc., 104, 6990.

    • Search Google Scholar
    • Export Citation
  • Fraile, R., and E. García-Ortega, 2005: Fitting an exponential distribution. J. Appl. Meteor., 44, 16201625.

  • Fraile, R., A. Castro, and J. L. Sanchez, 1992: Analysis of hailstone size distributions from a hailpad network. Atmos. Res., 28, 311326.

    • Search Google Scholar
    • Export Citation
  • Fraile, R., J. L. Sanchez, J. L. de la Madrid, A. Castro, and J. L. Marcos, 1999: Some results from the hailpad network in Leon (Spain): Noteworthy correlations among hailfall parameters. Theor. Appl. Climatol., 64, 105117.

    • Search Google Scholar
    • Export Citation
  • Fraile, R., A. Castro, L. Lopez, J. L. Sanchez, and C. Palencia, 2003: The influence of melting on hailstone size distribution. Atmos. Res., 67–68, 203213.

    • Search Google Scholar
    • Export Citation
  • Fraile, R., C. Palencia, A. Castro, D. Giaiotti, and F. Stel, 2009: Fitting an exponential distribution: Effect of discretization. Atmos. Res., 93, 636640.

    • Search Google Scholar
    • Export Citation
  • Giaiotti, D. B., and F. Stel, 2006: The effects of environmental water vapor on hailstone size distributions. Atmos. Res., 82, 455462.

    • Search Google Scholar
    • Export Citation
  • Giaiotti, D. B., E. Gianesini, and F. Stel, 2001: Heuristic considerations pertaining to hailstone size distributions in the plain of Friuli-Venezia Giulia. Atmos. Res., 57, 269288.

    • Search Google Scholar
    • Export Citation
  • Hohl, R., H.-H. Schiesser, and D. Aller, 2002a: Hailfall: The relationship between radar-derived hail kinetic energy and hail damage to buildings. Atmos. Res., 63, 177207.

    • Search Google Scholar
    • Export Citation
  • Hohl, R., H.-H. Schiesser, and I. Knepper, 2002b: The use of weather radars to estimate hail damage to automobiles: An exploratory study in Switzerland. Atmos. Res., 61, 215238.

    • Search Google Scholar
    • Export Citation
  • Lee, G., and I. Zawadzki, 2005: Variability of drop size distributions: Time-scale dependence of the variability and its effects on rain estimation. J. Appl. Meteor., 44, 241255.

    • Search Google Scholar
    • Export Citation
  • Long, A. B., R. J. Matson, and E. L. Crow, 1980: The hailpad: Materials, data reduction and calibration. J. Appl. Meteor., 19, 13001313.

    • Search Google Scholar
    • Export Citation
  • Lozowski, E. P., and G. S. Strong, 1978: On the calibration of hailpads. J. Appl. Meteor., 17, 521528.

  • Marshall, J. S., and W. M. Palmer, 1948: The distribution of raindrops with size. J. Atmos. Sci., 5, 165166.

  • Mezeix, J. F., and P. Admirat, 1978: Measurement of hail at ground level. Atmos.–Ocean, 16, 6188.

  • Palencia, C., C. Berthet, M. Massot, A. Castro, J. Dessens, and R. Fraile, 2007: On the individual calibration of hailpads. Atmos. Res., 83, 493504.

    • Search Google Scholar
    • Export Citation
  • Palencia, C., A. Castro, D. Giaiotti, F. Stel, F. Vinet, and R. Fraile, 2009: Hailpad-based research: A bibliometric review. Atmos. Res., 93, 664670.

    • Search Google Scholar
    • Export Citation
  • Palencia, C., D. Giaiotti, F. Stel, A. Castro, and R. Fraile, 2010: Maximum hailstone size: Relationship with meteorological variables. Atmos. Res., 96, 256265.

    • Search Google Scholar
    • Export Citation
  • Parker, M. D., I. C. Ratcliffe, and G. M. Henebry, 2005: The July 2003 Dakota hailswaths: Creation, characteristics, and possible impacts. Mon. Wea. Rev., 133, 12411260.

    • Search Google Scholar
    • Export Citation
  • Prieto, R., L. Gimeno, R. García, R. Herrera, E. Hernández, and P. Ribera, 1999: Interannual variability of hail-days in the Andes region since 1885. Earth Planet. Sci. Lett., 171, 503509.

    • Search Google Scholar
    • Export Citation
  • Rinehart, R. E., 1983: Out-of-level instruments: Errors in hydrometeor spectra and precipitation measurements. J. Climate Appl. Meteor., 22, 14041410.

    • Search Google Scholar
    • Export Citation
  • Roos, D. V. D. S., 1978: Hailstone size inferred from dents in cold-rolled aluminum sheet. J. Appl. Meteor., 17, 12341239.

  • Sánchez, J. L., R. Fraile, J. L. de La Madrid, M. T. de La Fuente, P. Rodríguez, and A. Castro, 1996: Crop damage: The hail size factor. J. Appl. Meteor., 35, 15351541.

    • Search Google Scholar
    • Export Citation
  • Segele, Z. T., D. J. Stensrud, I. C. Ratcliffe, and G. M. Henebry, 2005: Influence of a hailstreak on boundary layer evolution. Mon. Wea. Rev., 133, 942960.

    • Search Google Scholar
    • Export Citation
  • Smith, P. L., 2003: Raindrop size distributions: Exponential or gamma—Does the difference matter? J. Appl. Meteor., 42, 10311034.

  • Smith, P. L., and A. Waldvogel, 1989: On determinations of maximum hailstone sizes from hailpad observations. J. Appl. Meteor., 28, 7176.

    • Search Google Scholar
    • Export Citation
  • Smith, P. L., and D. V. Kliche, 2005: The bias in moment estimators for parameters of drop size distribution functions: Sampling from exponential distributions. J. Appl. Meteor., 44, 11951205.

    • Search Google Scholar
    • Export Citation
  • Sneyers, R., 1990: On the statistical analysis of series of observations. WMO Tech. Note 143, 192 pp.

  • Ulbrich, C. W., 1974: Analysis of Doppler radar spectra of hail. J. Appl. Meteor., 13, 387396.

  • Vento, D., 1976: The hailpad calibration for Italian hail damage documentation. J. Appl. Meteor., 15, 10181022.

  • Vento, D., 1978: L’angle de chute au sol de la grêle. Atmos.–Ocean, 16, 8185.

  • Vinet, F., 2001: Climatology of hail in France. Atmos. Res., 56, 309323.

  • Wong, R. K. W., N. Chidambaram, L. Cheng, and M. English, 1988: The sampling variations of hailstone size distributions. J. Appl. Meteor., 27, 254260.

    • Search Google Scholar
    • Export Citation
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Dent Overlap in Hailpads: Error Estimation and Measurement Correction

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  • 1 Departamento de Física, IMARENAB, Universidad de León, León, Spain
  • | 2 ARPA FVG, Palmanova, Italy
  • | 3 Departamento de Física, IMARENAB, Universidad de León, León, Spain
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Abstract

The measurement of the physical characteristics of hailstones reaching the ground is usually carried out by means of hailpads, on which the impact of hailstones leaves dents. Hailstone dents provide information about parameters, such as the number N of hailstones, their size M, and their kinetic energy E. In the case of intense hailfalls, however, the dents often overlap and the final measurement may not be totally reliable. This paper presents a computerized simulation with the aim of assessing measurement errors caused by dent overlap. The simulated dents represent several random hailfalls with both exponential size distributions and monodispersed size distributions. The simulated hailpads were measured following the procedure employed in the case of hailpads exposed to authentic hailfalls, and it was thus possible to assess the error due to dent overlap. The results show that dent overlap makes it impossible to measure all the dents, which means that in a real hailfall the number of hailstones registered will often be lower than the number of hailstones that actually hit the ground (up to 25% may go undetected). Consequently, the energy and mass of the hailstones are also underestimated (they may be up to 50% higher than the values registered on a hailpad). The maximum size registered, however, does not depend on the degree of overlapping and neither does the slope parameter λ of the exponential distribution, except when λ takes higher values. Finally, the authors suggest a heuristic correction of the data obtained by real hailpads based on the results of the simulations. An example is provided that applies these corrections to the 228 hailfalls registered by the Italian hailpad network over a period of 10 yr. The results show that, on average, the correction applied because of overlapping increases the number of hailstones in 3.2%, the mass in 1.9%, and the energy in 5.4%. However, there are cases in which these corrections reached much higher values of up to 6.9% in N and M, and up to 25.2% in E. It is therefore advisable to correct dent overlap before carrying out a regional climatic study of hail, since this study would certainly be affected by the errors accumulated by all the hailpads.

Corresponding author address: Roberto Fraile, Departamento de Física, Facultad de CC Biológicas y Ambientales, Universidad de León, 24071 León, Spain. E-mail: roberto.fraile@unileon.es

Abstract

The measurement of the physical characteristics of hailstones reaching the ground is usually carried out by means of hailpads, on which the impact of hailstones leaves dents. Hailstone dents provide information about parameters, such as the number N of hailstones, their size M, and their kinetic energy E. In the case of intense hailfalls, however, the dents often overlap and the final measurement may not be totally reliable. This paper presents a computerized simulation with the aim of assessing measurement errors caused by dent overlap. The simulated dents represent several random hailfalls with both exponential size distributions and monodispersed size distributions. The simulated hailpads were measured following the procedure employed in the case of hailpads exposed to authentic hailfalls, and it was thus possible to assess the error due to dent overlap. The results show that dent overlap makes it impossible to measure all the dents, which means that in a real hailfall the number of hailstones registered will often be lower than the number of hailstones that actually hit the ground (up to 25% may go undetected). Consequently, the energy and mass of the hailstones are also underestimated (they may be up to 50% higher than the values registered on a hailpad). The maximum size registered, however, does not depend on the degree of overlapping and neither does the slope parameter λ of the exponential distribution, except when λ takes higher values. Finally, the authors suggest a heuristic correction of the data obtained by real hailpads based on the results of the simulations. An example is provided that applies these corrections to the 228 hailfalls registered by the Italian hailpad network over a period of 10 yr. The results show that, on average, the correction applied because of overlapping increases the number of hailstones in 3.2%, the mass in 1.9%, and the energy in 5.4%. However, there are cases in which these corrections reached much higher values of up to 6.9% in N and M, and up to 25.2% in E. It is therefore advisable to correct dent overlap before carrying out a regional climatic study of hail, since this study would certainly be affected by the errors accumulated by all the hailpads.

Corresponding author address: Roberto Fraile, Departamento de Física, Facultad de CC Biológicas y Ambientales, Universidad de León, 24071 León, Spain. E-mail: roberto.fraile@unileon.es
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