Advances in Science and Research www.adv-sci-res.net 1992-0628 1992-0636 2 7th EMS Annual Meeting and 8th European Conference on Applications of Meteorology 2007 2008 10.5194/asr-2-61-2008 http://www.adv-sci-res.net/2/61/2008/ http://www.adv-sci-res.net/2/61/2008/asr-2-61-2008.html http://www.adv-sci-res.net/2/61/2008/asr-2-61-2008.pdf 61 64 2008-05-22 Heavy rain events in the Western Mediterranean: an atmospheric pattern classification C. Martínez cristina.martinez@inm.es J. Campins A. Jansà A. Genovés Centro Meteorológico en Illes Balears, Instituto Nacional de Meteorología, Spain Heavy rain is one of the most important high-impact weather phenomena that occasionally affect Mediterranean areas. The aim of this study is to achieve a classification of atmospheric patterns related to heavy rain events in both French and Spanish Mediterranean regions. The classification is made on some atmospheric fields (geopotential at 1000 hPa and at 500 hPa and temperature at 850 hPa) of HIRLAM-INM-0.5° operational analysis, for heavy rain events included in the High Impact Weather MEDEX database. It covers a period of roughly 7 and a half years, from January 1997 to May 2004. A Principal Components Analysis was conducted to reduce the number of variables. After that, by means of a Cluster Analysis, the heavy rain events are classified into 8 atmospheric patterns. The results show a good relationship between regions affected by heavy rain and atmospheric patterns, in the sense that the same atmospheric patterns usually produce heavy rain in different regions, and heavy rain in different regions is usually due to specific atmospheric patterns. Andenberg, M. R.: Cluster analysis for applications, Academic Press, New York, 359 pp., 1973. Campins, J., Jansà, A., and Genovés, A.: Heavy rain and strong wind events and cyclones in the Balearics, Adv. Geosci., 7, 73–77, 2006. Cressman, G. P.: An operational objective analysis system, Mon. Weather Rev., 87, 367–374, 1959. Esteban, P., Jones, P. D., Martín-Vide, J., and Mases, M.: Atmospheric circulation patterns related to heavy snowfall days in Andorra, Pyrenees, Int. J. Climatol., 25, 319–329, 2005. Houssos, E. and Bartzokas, A.: Extreme precipitations events in NW Greece, Adv. Geosci., 7, 91–96, 2006. Jansà, A., Genovés, A., Picornell, M. A., Campins, J., Riosalido, R., and Carretero, O.: Western Mediterranean cyclones and heavy rain. Part 2: Statistical approach, Meteorol. Appl. 8, 43–56, 2001. Lana, A., Campins, J., Genovés, A., and Jansà, A.: Atmospheric patterns for heavy rain events in the Balearic Islands, Adv. Geosci., 12, 27–32, 2007. Plaut, G., Schuepbach, E., and Doctor, M.: Heavy precipitation events over a few Alpine sub-regions and the links with large-scale circulations, 1971–1995, Climate Res., 17, 285–302, 2001. Romero, R., Sumner, G., Ramis, C., and Genovés, A.: A classification of the atmospheric circulation patterns producing significant daily rainfall in the Spanish Mediterranean area, Int. J. Climatol., 19, 765–785, 1999. Trigo, R. M. and DaCamara, C. C.: Circulation weather types and their influence on the precipitation regime in Portugal, Int. J. Climatol., 20, 1559–1581, 2000. Wilks, D.: Statistical methods in the atmospheric sciences, Academic Press, New York, 1995. Yarnal, B.: Synoptic climatology in environmental analysis, Belhaven Press, London, 1993.