24 November 2015

How Sensitive are the Pacific-North Atlantic Teleconnections to the Position and Intensity of El Nino Related Warming


It has been shown that climate anomalies in the tropical Pacific can lead the tropical Atlantic by at least several seasons on interannual timescales, but this connection has appeared to be intermittent.  Here we show that it depends on the type of El Niño event such that El Niño Modoki events in the central Pacific, and eastern Pacific El Niño events, have different connections to the tropical Atlantic.  First we analyze observations for composite Modoki and eastern Pacific El Niño events to quantify those connections through the atmosphere to the tropical Atlantic.  Then idealized SST forcing experiments are run for different regions in the tropical Pacific to isolate the forcing effects on the tropical Atlantic.  We show that the location, rather than strength, of SST warming in the central-western Pacific is more important for producing atmospheric teleconnections that affect the tropical Atlantic, with the eastern Pacific El Niño events producing the strongest teleconnections to force a lagged warming in the tropical Atlantic.

Gerald Meehl