A teleconnection is a statistically significant relationship between meteorological or climate anomalies in geographically distant regions, often separated by thousands of kilometres. These remote connections are established through planetary waves (Rossby waves) in atmospheric circulation and ocean-atmosphere interactions that transmit climate signals on a global scale.
Main patterns
The best-known teleconnection patterns include: the North Atlantic Oscillation (NAO), which controls winter weather in Europe and Spain; the Arctic Oscillation (AO); ENSO (El Nino-Southern Oscillation), the most powerful globally; the East Atlantic (EA) pattern; and the MJO on intraseasonal scales. Each is defined by a numerical index quantifying the positive or negative phase of the pattern.
For Spain, the NAO is the most influential teleconnection: a negative NAO (relatively low pressure over Iceland) favours rainy winters on the Iberian Peninsula by deflecting Atlantic depressions toward lower latitudes, while a positive NAO brings dry and mild winters. The NAO explains up to 40-60 % of winter precipitation variability in western Iberia.
Teleconnections are fundamental tools for seasonal prediction: if a pattern is in a given phase, probabilities can be estimated for a region being warmer/cooler or wetter/drier than normal. See also: El Nino, Madden-Julian Oscillation.