Accession Number : ADP008735

Title :   Principal Oscillation Pattern Analysis of the Intraseasonal Variability in the Equatorial Pacific Ocean,

Corporate Author : MAX-PLANCK-INST FUER METEOROLOGIE HAMBURG (GERMANY F R)

Personal Author(s) : Von Storch, Hans

Report Date : NOV 1993

Pagination or Media Count : 27

Abstract : In the present paper the concept of the principal oscillation pattern (POP) analysis is reviewed. This technique is used to simultaneously infer the characteristic patterns and time scales of a vector time series. The POPs may be seen as the normal modes of a linearized system whose system matrix is estimated from data. As a demonstration, the POP technique is used for the analysis of the intraseasonal variability in the equatorial Pacific Ocean; first results are presented. Daily observations of temperature and currents in the upper 500 m of the equatorial Pacific, recorded by moored buoys, are analyzed with respect to intraseasonal (40-180 day band) variations. Two oscillatory highly coherent modes are found with periods between 65 and 120 days. Both modes propagate eastward along the equator. The modes are clearly reflected in both the zonal currents and the temperatures, which trail behind the zonal currents by 45 deg. In the slower of the two modes, the temperature signal propagates more slowly than the zonal current signal, and no signal occurs in the meridional current. The mode's activity is enhanced during warm events of the Southern Oscillation. In the faster mode a signal also appears in the meridional current. Its amplitude exhibits an annual cycle, with variance on the annual and on the semiannual period. The slower mode might be an equatorial Kelvin wave but the faster mode, which has significant meridional current component, is inconsistent with the concept of an equatorial Kelvin wave.

Descriptors :   *OCEAN CURRENTS, *TIME SERIES ANALYSIS, *STATISTICAL ANALYSIS, DATA PROCESSING, EQUATORIAL REGIONS, PACIFIC OCEAN, SIGNAL PROCESSING, OCEAN ENVIRONMENTS, GERMANY.

Subject Categories : Physical and Dynamic Oceanography
      Numerical Mathematics
      Statistics and Probability

Distribution Statement : APPROVED FOR PUBLIC RELEASE