Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 14 1 2010 10.5194/hess-14-129-2010 http://www.hydrol-earth-syst-sci.net/14/129/2010/ http://www.hydrol-earth-syst-sci.net/14/129/2010/hess-14-129-2010.html http://www.hydrol-earth-syst-sci.net/14/129/2010/hess-14-129-2010.pdf 129 139 2010-01-21 Characteristics of 2-D convective structures in Catalonia (NE Spain): an analysis using radar data and GIS M. Barnolas mbarnolas@meteo.cat T. Rigo M. C. Llasat GAMA Team, Dept. of Astronomy and Meteorology, Univ. of Barcelona, Avda. Diagonal, 647, 08028 Barcelona, Spain Servei Meteorològic de Catalunya, Barcelona, Spain Flood simulation studies use spatial-temporal rainfall data input into distributed hydrological models. A correct description of rainfall in space and in time contributes to improvements on hydrological modelling and design. This work is focused on the analysis of 2-D convective structures (rain cells), whose contribution is especially significant in most flood events. The objective of this paper is to provide statistical descriptors and distribution functions for convective structure characteristics of precipitation systems producing floods in Catalonia (NE Spain). To achieve this purpose heavy rainfall events recorded between 1996 and 2000 have been analysed. By means of weather radar, and applying 2-D radar algorithms a distinction between convective and stratiform precipitation is made. These data are introduced and analyzed with a GIS. In a first step different groups of connected pixels with convective precipitation are identified. Only convective structures with an area greater than 32 km² are selected. Then, geometric characteristics (area, perimeter, orientation and dimensions of the ellipse), and rainfall statistics (maximum, mean, minimum, range, standard deviation, and sum) of these structures are obtained and stored in a database. Finally, descriptive statistics for selected characteristics are calculated and statistical distributions are fitted to the observed frequency distributions. Statistical analyses reveal that the Generalized Pareto distribution for the area and the Generalized Extreme Value distribution for the perimeter, dimensions, orientation and mean areal precipitation are the statistical distributions that best fit the observed ones of these parameters. The statistical descriptors and the probability distribution functions obtained are of direct use as an input in spatial rainfall generators. Barnolas, M. and Llasat, M. C.: A flood geodatabase and its climatological applications: the case of Catalonia for the last century, Nat. Hazards Earth Syst. Sci., 7, 271–281, 2007. Biggerstaff, M. I. and Listemaa, S. A.: An Improved Scheme for Convective/Stratiform Echo Classification Using Radar Reflectivity, J. Appl. Meteorol., 39(12), 2129–2150, 2000. Capsoni, C., Fedi, F., Magistroni, C., Paraboni, A., and Pawlina, A.: Data and theory for a new model of the horizontal structure of rain cells for propagation applications, Radio Sci., 22(3), 395–404, 1987. Capsoni, C., D'Amico, M., and Locatelli, P.: Statistical properties of rain cells in the Padana Valley, J. Atmos. Oceanic Tech., 25(12), 2230–2244, 2008. Ceperuelo, M., Llasat, M. C., and Rigo, T.: Rainfall events and Hailstorms Analysis Program (RHAP), Adv. Geosci., 7, 205–213, 2006. Chumchean, S., Seed, A., and Sharma, A.: Correcting of radar mean field bias using Kalman filtering approach, J. Hydrol., 317, 123–137, 2006. Cox, D. R. and Isham, V.: A simple spatial-temporal model of rainfall, Proc. Roy. Soc. Lond., A415, 317–328, 1988. De Lannoy, G. J. M., Verhoest, N. E. C., and De Troch, F. P.: Characteristics of rainstorms over a temperate region derived from multiple time series of weather radar images, J. Hydrol., 307, 126–144, 2005. García-Bartual R. and Marco, J.: A stochastic model of the internal structure of convective precipitation in time at a raingauge site, J. Hydrol., 118, 129–142 , 1990. García-Bartual, R. and Schneider, M.: Estimating maximum expected short-duration rainfall intensities from extreme convective storms, Phys. Chem. Earth Pt. B, 26(9), 675–681, 2001. Krajeswki, W. F. and Smith, J. A.: Radar hydrology: rainfall estimation, Adv. Water Resour., 25, 1387–1394, 2002. Feral, L., Mesnard, F., Sauvageot, H., Castanet, L., and Lemorton, J.: Rain cells shape and orientation distribution in South-West of France, Phys. Chem. Earth Pt. B, 25(10–12), 1073–1078, 2000. Llasat, M. C.: An objective classification of rainfall events on the basis of their convective features: Application to rainfall intensity in the north-east of Spain, Int. J. Climatol., 21, 1385–1400, 2001. Llasat, M. C., Ceperuelo, M., and Rigo, T.: Rainfall regionalization on the basis of the precipitation convective features using a raingauge network and weather radar observations, Atmos. Res., 83, 415–426, doi:10.1016/j.atmosres.2005.08.014, 2007. Marshall, J. S. and Palmer, W. M. K.: The distribution of raindrops with size, J. Meteorol., 5, 156–166, 1948. Morin, E. and Gabella, M.: Radar-based quantitative precipitation estimation over Mediterranean and dry climate regimes, J. Geophys. Res., 112, D20108, doi:10.1029/2006JD008206, 2007. Morin, E., Goodrich, D. C., Maddox, R. A., Gao, X., Gupta, H. V., and Sorooshian, S.: Rainfall modelling for integrating radar information into hydrological model, Atmos. Sci. Lett., 6(1), 23–30, 2005. Morin, E., Goodrich, D. C., Maddox, R. A., Gao, X., Gupta, H. V., and Sorooshian, S.: Spatial patterns in thunderstorm rainfall events and their coupling with watershed hydrological response, Adv. Water Resour., 29, 843–860, 2006. Northrop, P. J.: A clustered spatial-temporal model of rainfall, P. Roy. Soc. Lond., A454, 1875–1888, 1998. Rebora, N. and Ferraris, L.: The structure of convective rain cells at mid-latitudes, Adv. Geosci., 7, 31–35, 2006. Rigo, T. and Llasat, M. C.: A methodology for the classification of convective structures using meteorological radar: Application to heavy rainfall events on the Mediterranean coast of the Iberian Peninsula, Nat. Hazards Earth Syst. Sci., 4, 59–68, 2004. Rigo, T. and Llasat, M. C.: Analysis of mesoscale convective systems in Catalonia using meteorological radar for the period 1996–2000, Atmos. Res., 83, 458–472 , 2007. Rodriguez-Iturbe, I., Cox, D. R., and Isham, V.: Some models for rainfall based on stochastic point processes, Proc. Roy. Soc. Lond., A410, 269–88, 1987. Rodriguez-Iturbe, I., Cox, D. R., and Isham, V.: A point process model for rainfall: further developments, Proc. Roy. Soc. Lond., A417, 283–98, 1988. Salsón, S. and Garcia-Bartual, R.: A space-time rainfall generator for highly convective Mediterranean rainstorms, Nat. Hazards Earth Syst. Sci., 3, 103–114, 2003. Sánchez-Diezma, R.: Optimización de la medida de lluvia por radar meteorológico para su aplicación hidrológica, Ph. D. Thesis, Universitat Politecnica de Catalunya, 313~pp., 2001. Steiner, M., Houze Jr., R. A., and Yutter, S. E.: Climatological Characterization of Three-Dimensional Storm Structure from Operational Radar and Rain Gage Data, J. Appl. Meteor., 34(9), 1978–2007, 1995. Syed, K. H., Goodrich, D. C., Myers, D. E., and Sorooshian, S.: Spatial characteristics of thunderstorm rainfall fields and their relation to runoff, J. Hydrol., 271, 1–21, 2003. Trapero, L., Bech, J., Rigo, T., Pineda, N., and Forcadell, D.: Uncertainty of precipitation estimates in convective events by the Meteorological Service of Catalonia radar network, Atmos. Res., 93(1–3), 408–418, 4th European Conference on Severe Storms – 4ECSS, 4th European Conference on Severe Storms, 2009 Von Hardenberg, J., Ferraris, L., and Provenzale, A.: The shape of convective rain cells, Geophys. Res. Lett., 30(24), 2280, doi:10.1029/2003GL018539, 2003. Wheater, H. S., Isham, V. S., Cox, D. R., Chandler, R. E., Kakou, A., Northrop, P. J., Oh, L., Onof, C., and Rodriguez-Iturbe, I.: Spatial-temporal rainfall fields: modelling and statistical aspects, Hydrol. Earth Syst. Sci., 4, 581–601, 2000. Willems, P.: A spatial rainfall generator for small spatial scales, J. Hydrol., 252, 126–144, 2001.