La Niña diversity and Northwest Indian Ocean Rim teleconnections

Climate Dynamics
By: , and 



The differences in tropical Pacific sea surface temperature (SST) expressions of El Niño-Southern Oscillation (ENSO) events of the same phase have been linked with different global atmospheric circulation patterns. This study examines the dynamical forcing of precipitation during October–December (OND) and March–May (MAM) over East Africa and during December–March (DJFM) over Central-Southwest Asia for 1950–2010 associated with four tropical Pacific SST patterns characteristic of La Niña events, the cold phase of ENSO. The self-organizing map method along with a statistical distinguishability test was used to isolate La Niña events, and seasonal precipitation forcing was investigated in terms of the tropical overturning circulation and thermodynamic and moisture budgets. Recent La Niña events with strong opposing SST anomalies between the central and western Pacific Ocean (phases 3 and 4), force the strongest global circulation modifications and drought over the Northwest Indian Ocean Rim. Over East Africa during MAM and OND, subsidence is forced by an enhanced tropical overturning circulation and precipitation reductions are exacerbated by increases in moisture flux divergence. Over Central-Southwest Asia during DJFM, the thermodynamic forcing of subsidence is primarily responsible for precipitation reductions, with moisture flux divergence acting as a secondary mechanism to reduce precipitation. Eastern Pacific La Niña events in the absence of west Pacific SST anomalies (phases 1 and 2), are associated with weaker global teleconnections, particularly over the Indian Ocean Rim. The weak regional teleconnections result in statistically insignificant precipitation modifications over East Africa and Central-Southwest Asia.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title La Niña diversity and Northwest Indian Ocean Rim teleconnections
Series title Climate Dynamics
DOI 10.1007/s00382-014-2083-y
Volume 43
Issue 9-10
Year Published 2014
Language English
Publisher EBSCO Publishing
Publisher location Heidelberg
Contributing office(s) Earth Resources Observation and Science (EROS) Center
Description 18 p.
First page 2707
Last page 2724
Online Only (Y/N) N
Additional Online Files (Y/N) N