Climate centres use several standard regional averages of sea surface temperature anomalies as indices to monitor the state of the tropical oceans.
The diagrams below illustrate indices for the tropical Indian and Atlantic oceans as observed in recent months (in black), and the evolution predicted by the Met Office dynamical long-range ensemble forecast system (in red).
We also produce Tropical Pacific sea surface temperature forecasts.
Location of tropical Atlantic Ocean regions
Tropical North Atlantic (TNA) lies between 55°W and 15°W, 5°N to 25°N, and Tropical South Atlantic (TSA) lies between 30°W to 10°E, 20°S to the equator. The north-south difference TNA minus TSA across the equator is a measure of the tropical Atlantic sea surface temperature dipole.
Location of tropical Indian Ocean regions
Western Tropical Indian Ocean (WTIO) lies between 50°E and 70°E, 10°S to 10°N; Southeastern Tropical Indian Ocean (SETIO) lies between 90°E and 110°E, 10°S to the equator. The east-west difference WTIO minus SETIO is a measure of the tropical Indian Ocean Dipole (IOD).
