The present work was supported by the PRAXIS XXI program (Portuguese Office for Science and Technology), Grant BD/9508/96. The ECMWF dataset was supplied by the British Atmospheric Data Centre. We are grateful for the helpful comments made by two anonymous reviewers.
Alpert, P., B. U. Neeman, and Y. Shay-El, 1990a: Climatological analysis of Mediterranean cyclones using ECMWF data. Tellus,42A, 65–77.
——, ——, and ——, 1990b: Intermonthly variability of cyclone tracks in the Mediterranean. J. Climate,3, 1474–1478.
Barry, R. G., and R. J. Chorley, 1992: Atmosphere, Weather and Climate. 6th ed. Routledge, 392 pp.
Blender, R., K. Fraedrich, and F. Lunkeit, 1997: Identification of cyclone track regimes in North Atlantic. Quart. J. Roy. Meteor. Soc.,123, 727–741.
Buzzi, A., and S. Tibaldi, 1978: Cyclogenesis in the lee of Alps: A case study. Quart. J. Roy. Meteor. Soc.,104, 271–287.
ECMWF, 1995: User guide to ECMWF products. Edition 2.1. Meteorological Bull. M3.2., 71 pp.
Egger, J., P. Alpert, A. Tafferner, and B. Ziv, 1995: Numerical experiments on the genesis of Sharav cyclones: Idealised simulations. Tellus,47A, 162–174.
Flocas, A. A., 1988: Frontal depressions over the Mediterranean sea and Central Southern Europe. Mediterranée,4, 43–52.
——, and B. D. Giles, 1991: Distribution and intensity of frontal rainfall over Greece. Int. J. Climatol.,11, 429–442.
——, and T. S. Karacostas, 1996: Cyclogenesis over the Aegean Sea:Identifications and synoptic categories. Meteor. Appl.,3, 53–61.
Garrett, C., R. Outerbridge, and K. Thompson, 1993: Interannual variability in Mediterranean heat and buoyancy fluxes. J. Climate,6, 900–910.
Hartigan, J. A., 1975: Clustering Algorithms. Wiley and Sons, 351 pp.
HMSO, 1962: Weather in the Mediterranean I: General Meteorology. 2d ed. Her Majesty’s Stationery Office, 362 pp.
Hoskins, B. J., and P. J. Valdes, 1990: On the existence of storm-tracks. J. Atmos. Sci.,47, 1854–1864.
Jacobeit, J., 1987: Variations of trough position and precipitation patterns in the Mediterranean Area. J. Climatol.,7, 453–476.
Lefevre, R. J., and J. W. Nielsen-Gammon, 1995: An objective climatology of mobile troughs in the northern hemisphere. Tellus,47A, 638–655.
Mirkin, B., 1996: Mathematical Classification and Clustering. Kluwer Academic, 428 pp.
Murray, R. J., and I. Simmonds, 1991: A numerical scheme for tracking cyclone centres from digital data. Part I: Development and operation scheme. Aust. Meteor. Mag.,39, 155–166.
Nielsen, J. W., and R. M. Dole, 1992: A survey of extratropical cyclone characteristics during GALE. Mon. Wea. Rev.,120, 1156–1167.
Peixoto, J. P., and A. H. Oort, 1992: Physics of Climate. American Institute of Physics, 520 pp.
Petterssen, S., 1956: Weather Analysis and Forecasting. Vol. I, Motion and Motion Systems, McGraw-Hill, 428 pp.
Radinovic, D., 1987: Mediterranean cyclones and their influence on the weather and climate. PSMP Rep Series 24, WMO, Geneva, Switzerland, 131 pp.
Rodwell, M. J., and B. J. Hoskins, 1996: Monsoons and the dynamics of deserts. Quart. J. Roy. Meteor. Soc.,122, 1385–1404.
Roebber, P. J., 1984: Statistical analysis and updated climatology of explosive cyclones. Mon. Wea. Rev.,112, 1577–1589.
Serreze, M. C., 1995: Climatological aspects of cyclone development and decay in the Arctic. Atmos.–Ocean,33, 1–23.
——, F. Carse, R. G. Barry, and J. C. Rogers, 1997: Icelandic low cyclone activity: Climatological features, linkages with the NAO, and relationships with recent changes in the Northern Hemisphere circulation. J. Climate,10, 453–464.
Sinclair, M. R., 1994: An objective cyclone climatology for Southern Hemisphere. Mon. Wea. Rev.,122, 1156–1167.
Thorncroft, C. D., and H. A. Flocas, 1997: A case study of Saharan cyclogenesis. Mon. Wea. Rev.,125, 1147–1165.