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As of 2004, this project is no longer current. Please see the Research Programs page for a list of current research projects.
Application of the Wavelet Transform to the Characterization of Intraseasonal Oscillations
This project is aimed at application of the wavelet transform to the characterization of intraseasonal oscillations in sea surface temperature, wind stress, and sea level in eastern Pacific Ocean off Monterey, California. Oceanic responses to intraseasonal oscillations have been observed at many locations in the Indian and Pacific oceans extending from tropics to mid-latitudes. Despite extensive observational, modeling, and theoretical studies available, there does not seem to be a satisfactory explanation for all the features of intraseasonal oscillations. It remains one of the important unexplained components of current climate study. Associated with it there is substantial potential predictive ability on the time scale between a week and a season. The technique developed from this study will be also applicable to Great Lakes studies.
This project ended in 1999
This project has been revised and transformed as part of the new project "Rogue Waves and Explorations of Coastal Wave Characteristics." No further activities will be reported on this project.
1999 Accomplishments
Wavelet transform is a new and useful mathematical technique that has emerged only during the last fifteen years. Well developed in the mathematics and signal and image analyses fields, its applications have also been slowly extended to the oceanic and atmospheric fields. We have used wavelet transform in the wind waves studies and found significant new insights on wave grouping process. This year we applied the wavelet transform to two collaborative efforts on the study intraseasonal oscillations in sea surface temperature (SST), wind stress, and sea level off central California coast and the hazardous freak waves in the oceans. We found the results on intraseasonal oscillation show that the relationship between wind stress and SST to be stronger than wind stress and sea level which is generally consistent with dynamical implications. We also found clear and specific signature of the occurrence of freak waves shown in the wavelet spectrum.
Products
Liu, P.C. 2000. Wavlet transform and new perspective on coastal and oceanic engineering data analysis. Advances in Coastal and Ocean Engineering, Vol 6, (Philip Liu, Ed), World Scientific, 57-101.
Liu, P.C. 2000 Wave grouping characteristics in nearshore Great Lakes. Ocean Engineering, Vol. 27, 1221-1230.
Liu, P.C. 2000. Is the wind wave frequency spectrum outdated? Ocean Engineering 27:577-588.
Liu, P.C. 1999. A fifteen minute introduction of wavelet transform and applications. Proceedings, ASCE 1999 International Water Resources Engineering Conference.
Liu, P.C. and N. Mori. 1999. A wavelet transform analysis of freak waves in the ocean. Proceedings, ASCE 1999 International Water Resources Engineering Conference.
Liu, P.C. 1999. Wind waves in large lakes. Potential Climate Change Effects on Great Lakes Hydrodynamics and Water Quality, D.C.L. Lam and W.M. Schertzer, Eds., American Society of Civil Engineers, pp 5-1 to 5-15.
Last updated: May 16, 2003 mbl