Complex Principal Component Analysis of Sea Level Pressure Over Eastern North America and the Western Atlantic Ocean: A Search for Preferred Disturbance Activity Areas

摘要

The purpose of this study was to identify preferred areas of synoptic scale disturbance activity through use of the objective analysis technique called complex principal component analysis. The technique was applied to a sea level pressure data set consisting of twice daily observations (00 and 12 GMT) during the months of January, February, and 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 1986. The geopraphical area studied extended approximately from 30-120 deg west and from 25-60 deg north. The complex principal component analysis technique allows the detection of propagating features in the pressure data set. The original data set is augmented with its own Hilbert transform, which is nearly equivalent in the time domain to the quadrature spectrum in the frequency domain. Variance in the pressure field is felt to be a direct reflection of disturbance activity. Furthermore, when the data are filtered to a 'synoptic scale' frequency window, variance in the pressure field corresponds closely with cyclone and anticyclone storm tracks over a period of two to ten days. Resultws of this analysis produced four components that could be given a preliminary interpretation from a physical sense.