Fig. 3.

Influence of ocean conditions on winter and summer rains. Climatic diagram for Ensenada, Baja California (lat 31°53′N, long 115°35′W), a typical winter-rain area in northern Mexico (a), and negative correlation between mean annual SOI values and annual precipitation for the same station (b). Climatic diagram for Ixtepec, Oaxaca (lat 16°33′N, long 95°05′W), a typical monsoon-rain area in southern Mexico (c), and positive correlation between mean annual SOI values and annual precipitation observed for that station (d). The two stations were selected for the completeness of their long-term data series and their respective central locations within areas of mediterranean and monsoon-type weather regimes.