Complex principal component analysis of sea-level pressure over the eastern USA

The purpose of this study is to identify preferred areas of synoptic-scale disturbance activity through the use of the objective analysis technique called complex principal component analysis. This technique is applied to a sea-level pressure data set consisting of twice daily observations (00 and 12 GMT) for the months January through to March for the years 1973–1976 and 1979–1982. These months were chosen to encompass the time frame of the Genesis of Atlantic Lows Experiment (GALE) 1986. The geographical area studied extended from approximately 30°W to 120°W and 25°N to 60°N. The complex principal component analysis technique allows the detection of propagating features in the pressure data set. The eigenvalues, complex eigenvectors (components), and complex component scores are extracted from an augmented data matrix and are used to compute four measures that define the propagating features within the data set. Research has indicated a spatial relationship between cyclone and anticyclone tracks and the variance in station or sea-level pressure, especially when the pressure data have been filtered to examine a frequency window traditionally associated with synoptic-scale activity. The 2–10-day period was selected for examination of synoptic-scale activity in this study. The results of the analysis produced four components that could be given a preliminary, physical interpretation. The variability pattern produced by component 1 accounts for the movement of cyclones/anticyclones guided by the mean mid-tropospheric flow. Component 2 represents the cold air outbreak anticyclones that move south-eastward into the eastern USA. Component 3 is linked to the cold air outbreaks over the western USA and to cyclone movement in the eastern USA and Canada. Component 4 represents cyclones that move out of the central and southern states to become east coast systems. The results are not without ambiguities, which are discussed.

[1]  John D. Horel,et al.  A Rotated Principal Component Analysis of the Interannual Variability of the Northern Hemisphere 500 mb Height Field , 1981 .

[2]  Michael B. Richman,et al.  Obliquely Rotated Principal Components: An Improved Meteorological Map Typing Technique? , 1981 .

[3]  F. Sanders,et al.  Synoptic-Dynamic Climatology of the “Bomb” , 1980 .

[4]  Robert F. Cahalan,et al.  Sampling Errors in the Estimation of Empirical Orthogonal Functions , 1982 .

[5]  J. Wallace,et al.  An Observational Study of the Northern Hemisphere Wintertime Circulation , 1977 .

[6]  W. Klein.  THE FREQUENCY OF CYCLONES AND ANTICYCLONES IN RELATION TO THE MEAN CIRCULATION , 1958 .

[7]  Phillip A. Arkin,et al.  Biennial Variations in Surface Temperature over the United States as Revealed by Singular Decomposition , 1981 .

[8]  D. Hartmann.  Time Spectral Analysis of Mid-Latitude Disturbances , 1974 .

[9]  K. M. Zishka,et al.  The Climatology of Cyclones and Anticyclones over North America and Surrounding Ocean Environs for January and July, 1950–77 , 1980 .

[10]  T. Barnett.  Interaction of the Monsoon and Pacific Trade Wind System at Interannual Time Scales Part I: The Equatorial Zone , 1983 .

[11]  M. Blackmon,et al.  A Climatological Spectral Study of the 500 mb Geopotential Height of the Northern Hemisphere. , 1976 .

[12]  L. Jenne.  Data Sets for Meteorological Research , 1975 .

[13]  J. Wallace,et al.  Horizontal structure of 500 mb height fluctuations with long, intermediate and short time scales , 1984 .

[14]  Clayton H. Reitan.  Frequencies of Cyclones and Cyclogenesis for North America, 1951–1970 , 1974 .

[15]  R. A. Madden,et al.  Geographical Variations in the Vertical Structure of Geopotential Height Fluctuations1 , 1979 .

[16]  S. Colucci.  Winter Cyclone Frequencies over the Eastern United States and Adjacent Western Atlantic , 1976 .

[17]  W. Klein.  Specification of sea‐level pressure from 700‐mb height , 1967 .

[18]  W. Klein.  A HEMISPHERIC STUDY OF DAILY PRESSURE VARIABILITY AT SEA LEVEL AND ALOFT , 1951 .

[19]  J. Wallace,et al.  Empirical Orthogonal Representation of Time Series in the Frequency Domain. Part I: Theoretical Considerations , 1972 .

[20]  John M. Wallace,et al.  Time Variation of 500 mb Height Fluctuations with Long, Intermediate and Short Time Scales as Deduced from Lag-Correlation Statistics , 1984 .

[21]  G. White,et al.  zonal Wavenumber Characteristics of Northern Hemisphere Transient Eddies , 1982 .

[22]  Paul Roebber.  Statistical analysis and updated climatology of explosive cyclones , 1984 .

[23]  J. Horel.  Complex Principal Component Analysis: Theory and Examples , 1984 .

[24]  L. H. Horn,et al.  Geographical and Seasonal Distribution of North American Cyclogenesis, 1958–1977 , 1981 .