scholarly journals An Extended Pacific–North American Index from Upper-Air Historical Data Back to 1922

2008 ◽  
Vol 21 (6) ◽  
pp. 1295-1308 ◽  
Author(s):  
Tracy Ewen ◽  
Stefan Brönnimann ◽  
Jeffrey Annis
Keyword(s):  
North American ◽  
Southern Oscillation ◽  
Surface Air Temperature ◽  
Reanalysis Data ◽  
Special Focus ◽  
Statistical Regression ◽  
Climate System Model ◽  
Pacific North American ◽  
The Pacific ◽  
Validation Experiments

Abstract This paper presents a reconstruction of a Pacific–North America (PNA) index from historical upper-level data for the period 1922–47. The data have been compiled from a number of sources and cover the Pacific–North American sector relatively well over this time period. Temperature and geopotential height profiles from aircraft, kite, and radiosonde ascents back to 1922 have been digitized and validated. Wind speed and direction from pilot balloon data back to the early 1920s, provided by NCAR, have also been used. A statistical regression approach is used for the reconstruction and calibrated in the post-1948 period using NCEP–NCAR reanalysis data. Split-sample validation experiments were performed within the NCEP–NCAR period, and sensitivity experiments with different subsets of predictors were performed. Similar reconstructions and validation experiments were carried out using a 540-yr control run from the Community Climate System Model, version 3 (CCSM3). The reconstructed index series together with validation statistics for both the historical and model data are presented. Excellent reconstruction skill is found for the winter months, while the reconstructions are somewhat worse in summer. Compared with a reconstruction based only on surface data, the addition of the newly digitized upper-air stations improves the reconstruction skill in all seasons. The historical reconstruction is presented with respect to its imprint on hemispheric fields of surface air temperature, sea level pressure, and precipitation with a special focus on extreme cases. In addition, the extended PNA index is compared with indices of the North Atlantic Oscillation, the Pacific decadal oscillation, and the El Niño–Southern Oscillation. The relationship to these indices is found to be stationary over the analysis period.

scholarly journals Coupling functions in climate

2019 ◽  
Vol 377 (2160) ◽  
pp. 20190006 ◽  
Author(s):  
Woosok Moon ◽  
John S. Wettlaufer
Keyword(s):  
Dynamical Systems ◽  
Seasonal Variability ◽  
Southern Oscillation ◽  
Surface Air Temperature ◽  
Climate Indices ◽  
Dynamical Interaction ◽  
Stochastic Dynamical System ◽  
Mature Phase ◽  
The Pacific ◽  
The Indian Ocean

We examine how coupling functions in the theory of dynamical systems provide a quantitative window into climate dynamics. Previously, we have shown that a one-dimensional periodic non-autonomous stochastic dynamical system can simulate the monthly statistics of surface air temperature data. Here, we expand this approach to two-dimensional dynamical systems to include interactions between two sub-systems of the climate. The relevant coupling functions are constructed from the covariance of the data from the two sub-systems. We demonstrate the method on two tropical climate indices, the El-Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD), to interpret the mutual interactions between these two air–sea interaction phenomena in the Pacific and Indian Oceans. The coupling function reveals that the ENSO mainly controls the seasonal variability of the IOD during its mature phase. This demonstrates the plausibility of constructing a network model for the seasonal variability of climate systems based on such coupling functions. This article is part of the theme issue ‘Coupling functions: dynamical interaction mechanisms in the physical, biological and social sciences’.

scholarly journals Intraseasonal and Interannual Variability in North American Storm Tracks and Its Relationship to Equatorial Pacific Variability

2013 ◽  
Vol 141 (10) ◽  
pp. 3610-3625 ◽  
Author(s):  
Kevin M. Grise ◽  
Seok-Woo Son ◽  
John R. Gyakum
Keyword(s):  
North America ◽  
Interannual Variability ◽  
North American ◽  
Southern Oscillation ◽  
Extratropical Cyclones ◽  
The North ◽  
The Pacific ◽  
Cyclone Tracks ◽  
Lagrangian Tracking ◽  
The North Atlantic Oscillation

Abstract Extratropical cyclones play a principal role in wintertime precipitation and severe weather over North America. On average, the greatest number of cyclones track 1) from the lee of the Rocky Mountains eastward across the Great Lakes and 2) over the Gulf Stream along the eastern coastline of North America. However, the cyclone tracks are highly variable within individual winters and between winter seasons. In this study, the authors apply a Lagrangian tracking algorithm to examine variability in extratropical cyclone tracks over North America during winter. A series of methodological criteria is used to isolate cyclone development and decay regions and to account for the elevated topography over western North America. The results confirm the signatures of four climate phenomena in the intraseasonal and interannual variability in North American cyclone tracks: the North Atlantic Oscillation (NAO), the El Niño–Southern Oscillation (ENSO), the Pacific–North American pattern (PNA), and the Madden–Julian oscillation (MJO). Similar signatures are found using Eulerian bandpass-filtered eddy variances. Variability in the number of extratropical cyclones at most locations in North America is linked to fluctuations in Rossby wave trains extending from the central tropical Pacific Ocean. Only over the far northeastern United States and northeastern Canada is cyclone variability strongly linked to the NAO. The results suggest that Pacific sector variability (ENSO, PNA, and MJO) is a key contributor to intraseasonal and interannual variability in the frequency of extratropical cyclones at most locations across North America.

scholarly journals A new look at the Pacific/North American Index

2001 ◽  
Vol 28 (8) ◽  
pp. 1519-1522 ◽  
Author(s):  
Sergei Rodionov ◽  
Raymond Assel
Keyword(s):  
North American ◽  
Pacific North American ◽  
The Pacific ◽  
New Look

scholarly journals Seasonal Variation and Spatial Patterns of the Atmospheric Component of the Pacific Decadal Oscillation

2013 ◽  
Vol 26 (5) ◽  
pp. 1575-1594 ◽  
Author(s):  
Catrin M. Mills ◽  
John E. Walsh
Keyword(s):  
United States ◽  
North America ◽  
Air Temperature ◽  
Pacific Decadal Oscillation ◽  
Southern Oscillation ◽  
Grid Point ◽  
Southeastern United States ◽  
Surface Air Temperature ◽  
The Pacific ◽  
Difference Fields

Abstract The Pacific decadal oscillation (PDO) is an El Niño–Southern Oscillation (ENSO)-like climate oscillation that varies on multidecadal and higher-frequency scales, with a sea surface temperature (SST) dipole in the Pacific. This study addresses the seasonality, vertical structure, and across-variable relationships of the local North Pacific and downstream North American atmospheric signal of the PDO. The PDO-based composite difference fields of 500-mb geopotential height, surface air temperature, sea level pressure, and precipitation vary not only across seasons, but also from one calendar month to another within a season, although month-to-month continuity is apparent. The most significant signals occur in western North America and in the southeastern United States, where a positive PDO is associated with negative heights, consistent with underlying temperatures in the winter. In summer, a negative precipitation signal in the southeastern United States associated with a positive PDO phase is consistent with a ridge over the region. When an annual harmonic is fit to the 12 monthly surface air temperature differences at each grid point, the PDO temperature signal peaks in winter in most of North America, while a peak in summer occurs in the southeastern United States. Approximately 25% of the variance of the PDO index is accounted for by ENSO. Atmospheric composite differences based on a residual (ENSO linearly removed) PDO index have many similarities to those of the full PDO signal.

Synoptic analysis of the Pacific-North American teleconnection pattern

2011 ◽  
Vol 137 (655) ◽  
pp. 329-346 ◽  
Author(s):  
Christian Franzke ◽  
Steven B. Feldstein ◽  
Sukyoung Lee
Keyword(s):  
North American ◽  
Teleconnection Pattern ◽  
Pacific North American ◽  
Synoptic Analysis ◽  
The Pacific
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