Figure 1: (a) Map of the Mediterranean Sea. The main basins and subbasins are indicated. Symbols are placed in the locations selected for pressure differences in the station-based MO indices (a triangle for Algiers-Cairo, a square for Gibraltar-Israel, a circle for France-Levantine, and a diamond for Marseille-Jerusalem). ((b)-(c)) Composites of sea level pressure anomalies (mbar) in the 1958–2008 period during the positive (higher quartile, (b)) and negative (lower quartile, (c)) phases of the index.