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Advances in Meteorology
Volume 2016, Article ID 4797103, 8 pages
Research Article

The Classification of Synoptic-Scale Eddies at 850 hPa over the North Pacific in Wintertime

1Meteorological and Oceanography College, PLA University of Science and Technology, Nanjing 211101, China
2LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
3PLA, Unit 95178, Nanning 530226, China

Received 25 April 2016; Revised 19 July 2016; Accepted 2 August 2016

Academic Editor: Anthony R. Lupo

Copyright © 2016 Linlin Xia et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Empirical orthogonal function (EOF) is applied to the study of the synoptic-scale eddies at 850 hPa over the North Pacific in winter from 1948 to 2010. The western developing pattern synoptic-scale eddies (WSE) and the eastern developing pattern synoptic-scale eddies (ESE) are extracted from the first four leading modes of EOF analysis of high-pass filtered geopotential height. The results show the following: (1) The WSE and the ESE both take the form of a wave train propagating eastward. The WSE reach their largest amplitude around the dateline in the North Pacific, while the largest amplitude of ESE occurs in the northeast Pacific. (2) The WSE and ESE are the most important modes of the synoptic-scale eddies at 850 hPa over the North Pacific, which correspond to the two max value centers of the storm track. (3) In addition to geopotential height, the WSE and the ESE also leave their wave-like footprints in the temperature, meridional wind, and vertical velocity fields, which assume typical baroclinic wave features. (4) The WSE and the ESE have an intrinsic time scale of four days and experience a “midwinter suppression” corresponding to the midwinter suppression of storm tracks.