Variability of North Pacific Sea Ice and East Asia–North Pacific Winter Climate

• Published in: Journal of climate Vol. 20; no. 10; pp. 1991 - 2001
• Main Authors: Liu, Jiping, Zhang, Zhanhai, Horton, Radley M., Wang, Chunyi, Ren, Xiaobo
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 15.05.2007
• Subjects: Anticyclones; Arctic Oscillation; Atmosphere; Atmospheric circulation; Atmospherics; Climate; Climate variability; Climatology. Bioclimatology. Climate change; Datasets; Dipoles; Earth, ocean, space; East Asian monsoon; Easterlies; Exact sciences and technology; External geophysics; Food chains; General circulation models; Heat; Heat flux; Ice; Jet stream; Jet streams; Jet streams (meteorology); Marine; Meteorological satellites; Meteorology; Modes; Physics of the oceans; Precipitation; Rivers; Sea ice; Sea level; Seas; Standard deviation; Statistical significance; Surface temperature; Time series; Variability; Westerlies; Wind; Winter; Winter climates; Winter monsoon; Northeast Pacific; North Pacific; Asia; Bering Sea; East Asia; Sea of Okhotsk; Arctic region; PN, Arctic; INW, Okhotsk Sea; IN, Bering Sea; IN, North Pacific; China, People's Rep; Russia, Siberia; INW, Russia, Siberia; Anticyclone; atmospheric precipitation; Atmosphere cryosphere interaction; Barometric depression; Winter monsoon; Ice cover; principal components analysis; Dynamical climatology; Winter; Asia; Climate variability; sea ice; Jet stream; cooling; warming; Pacific Ocean; Effect on climate; atmospheric circulation
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/jcli4105.1

Sea ice variability in the North Pacific and its associations with the east Asia–North Pacific winter climate were investigated using observational data. Two dominant modes of sea ice variability in the North Pacific were identified. The first mode features a dipole pattern between the Sea of Okhotsk and the Bering Sea. The second mode is characterized by more uniform ice changes throughout the North Pacific. Using the principal components of the two dominant modes as the indices (PC1 and PC2), analyses show that the positive phases of PC1 feature a local warming (cooling) in the Sea of Okhotsk (the Bering Sea), which is associated with the formation of the anomalous anticyclone extending from the northern Pacific to Siberia, accompanied by a weakening of the east Asian jet stream and trough. The associated anomalous southeasterlies/easterlies reduce the climatological northwesterlies/westerlies, leading to warm and wet conditions in northeast China and central Siberia. The positive phases of PC2 are characterized by a strong local warming in the northern Pacific that coincides with the anomalous cyclone occupying the entire North Pacific, accompanied by a strengthening of the east Asia jet stream and trough. The associated anomalous northerlies intensify the east Asian winter monsoon (EAWM), leading to cold and dry conditions in the east coast of Asia. The intensified EAWM also strengthens the local Hadley cell, which in turn strengthens the east Asian jet stream and leads to a precipitation deficit over subtropical east Asia. The linkages between PC1 and PC2 and large-scale modes of climate variability were also discussed. It is found that PC1 is a better indicator than the Arctic Oscillation of the recent Siberian warming, whereas PC2 may be a valuable predictor of EAWM.