Interdecadal variations in ENSO teleconnection to the Indo-Western Pacific for 1870–2007

Slow modulation of interannual variability and its relationship to El Niño--Southern Oscillation (ENSO) is investigated for the period of 1870-2007 using shipboard surface meteorological observations along a frequently traveled track across the north Indian Ocean (NIO; from the Gulf of Aden through Malacca Strait) and the South China Sea (to Luzon Strait). During the decades in the late nineteenth--early twentieth century and in the late twentieth century, the El Niño--induced NIO warming persists longer than during the 1910s--mid-1970s, well into the summer following the peak of El Niño.

During the epochs of the prolonged NIO warming, rainfall drops and sea level pressure rises over the tropical northwest Pacific in summer following El Niño. Conversely, during the period when the NIO warming dissipates earlier, these atmospheric anomalies are not well developed. This supports the Indian Ocean capacitor concept as a mechanism prolonging El Niño influence into summer through the persistent Indian Ocean warming after El Niño itself has dissipated.