Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

A Simplified Linear Framework for Interpreting Patterns of Northern Hemisphere Wintertime Climate Variability

A Simplified Linear Framework for Interpreting Patterns of Northern Hemisphere Wintertime Climate... The principal patterns of variability of the extratropical Northern Hemisphere (NH) wintertime circulation are examined, based on 42 yr of data from the NCAR–NCEP reanalyses. The two-dimensional phase space defined by the two leading PCs of the monthly mean sea level pressure (SLP) field poleward of 20°N is used as a basis for surveying the structure of the geopotential height and surface air temperature (SAT) fields. Together these two patterns account for roughly half the variance of SLP on interannual time scales and longer, and virtually all the planetary-scale SLP trends over the 42-yr period of record. The leading EOF corresponds to the NH annular mode (NAM), and the second EOF resembles the Pacific–North America (PNA) pattern. The leading EOF of the monthly mean geopotential height field at various levels throughout the troposphere and lower stratosphere is well represented by linear combinations of these two SLP patterns, as are the intraseasonal and interannual SLP fields, the NAM, the North Atlantic Oscillation (NAO), the PNA pattern, the pattern corresponding to the North Pacific index (NP), the cold ocean–warm land (COWL) pattern, the seasaw between the depths of the Aleutian and Icelandic lows (AIS), and the leading EOFs of lower-tropospheric temperature and midtropospheric wind. The combined influence of these patterns on temperature and rainfall and other variables can be represented in terms of compact vectorial plots. Interesting differences emerge when the EOF analysis is performed separately on the intraseasonal and interannual components of the NH SLP field. The former patterns appear to be hemispherically trapped, whereas the latter appear to be reflections of global structures, with ENSO clearly dominating the structure of interannual EOF2. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Climate American Meteorological Society

A Simplified Linear Framework for Interpreting Patterns of Northern Hemisphere Wintertime Climate Variability

Quadrelli, Roberta; Wallace, John M.
Journal of Climate , Volume 17 (19) – May 19, 2003
Download PDF
17 pages

Loading next page...
 
/lp/american-meteorological-society/a-simplified-linear-framework-for-interpreting-patterns-of-northern-Q5yzRLyGez

References (37)

Publisher
American Meteorological Society
Copyright
Copyright © 2003 American Meteorological Society
ISSN
1520-0442
DOI
10.1175/1520-0442(2004)017<3728:ASLFFI>2.0.CO;2
Publisher site
See Article on Publisher Site

Abstract

The principal patterns of variability of the extratropical Northern Hemisphere (NH) wintertime circulation are examined, based on 42 yr of data from the NCAR–NCEP reanalyses. The two-dimensional phase space defined by the two leading PCs of the monthly mean sea level pressure (SLP) field poleward of 20°N is used as a basis for surveying the structure of the geopotential height and surface air temperature (SAT) fields. Together these two patterns account for roughly half the variance of SLP on interannual time scales and longer, and virtually all the planetary-scale SLP trends over the 42-yr period of record. The leading EOF corresponds to the NH annular mode (NAM), and the second EOF resembles the Pacific–North America (PNA) pattern. The leading EOF of the monthly mean geopotential height field at various levels throughout the troposphere and lower stratosphere is well represented by linear combinations of these two SLP patterns, as are the intraseasonal and interannual SLP fields, the NAM, the North Atlantic Oscillation (NAO), the PNA pattern, the pattern corresponding to the North Pacific index (NP), the cold ocean–warm land (COWL) pattern, the seasaw between the depths of the Aleutian and Icelandic lows (AIS), and the leading EOFs of lower-tropospheric temperature and midtropospheric wind. The combined influence of these patterns on temperature and rainfall and other variables can be represented in terms of compact vectorial plots. Interesting differences emerge when the EOF analysis is performed separately on the intraseasonal and interannual components of the NH SLP field. The former patterns appear to be hemispherically trapped, whereas the latter appear to be reflections of global structures, with ENSO clearly dominating the structure of interannual EOF2.

Journal

Journal of Climate – American Meteorological Society

Published: May 19, 2003

There are no references for this article.