* Corresponding author address:

• Main Authors: Yuko M. Okumura, Clara Deser, Aixue Hu, Axel Timmermann, Shang-ping Xie, Dr. Yuko, M. Okumura
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2008
• Subjects: Arctic; Pacific; aleutian low; North Atlantic; Subarctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.145.1414; http://iprc.soest.hawaii.edu/~xie/yuko-hosing-09.pdf

Sudden changes of the Atlantic meridional overturning circulation (AMOC) are believed to have caused large, abrupt climate changes over many parts of the globe during the last glacial and de-glacial period. This study investigates the mechanisms by which a large freshwater input to the subarctic North Atlantic and an attendant rapid weakening of the AMOC influence North Pacific climate by analyzing four different ocean-atmosphere coupled general circulation models (GCMs) under present-day or pre-industrial boundary conditions. When the coupled GCMs are forced with a 1 Sv freshwater flux anomaly in the subarctic North Atlantic, the AMOC nearly shuts down and the North Atlantic cools significantly. The South Atlantic warms slightly, shifting the Atlantic intertropical convergence zone southward. In addition to this Atlantic oceanatmosphere response, all the models exhibit cooling of the North Pacific, especially along the oceanic frontal zone, and deepening of the wintertime Aleutian Low, consistent with paleoclimate reconstructions. Detailed analysis of one coupled GCM identifies both oceanic and atmospheric pathways from the Atlantic to the North Pacific. The oceanic teleconnection contributes a large part of the North Pacific cooling: the freshwater input to the North Atlantic raises sea level in the Arctic