@CONFERENCE\{IMM2009-05786, author = "A. A. Nielsen and O. B. Andersen and P. Knudsen", title = "Recent sea level change analysed with kernel {EOF}", year = "2009", month = "jan", booktitle = "Danish Ocean Researchers' Meeting", volume = "", series = "", editor = "", publisher = "", organization = "", address = "Elsinore, Denmark", url = "http://www2.compute.dtu.dk/pubdb/pubs/5786-full.html", abstract = "This paper describes the application of a kernel version of empirical orthogonal functions (EOF) to detect patterns of interest in global monthly mean sea surface height anomalies from satellite altimetry during the last 17 years. The kernel version is based on a dual formulation also termed {Q-}mode analysis in which the data enter into the analysis via inner products in the Gram matrix only. In the kernel version the inner products are replaced by inner products between nonlinear mappings into higher dimensional feature space of the original data. Via kernel substitution also known as the kernel trick these inner products between the mappings are in turn replaced by a kernel function and all quantities needed in the analysis are expressed in terms of this kernel function. Results from the last 17 years have been obtained from analysing joint {TOPEX} and {JASON-}1 data over the period 1992-2008. Preliminary analysis shows some interesting features related to climate change and particularly the pulsing of the El Niņo/Southern Oscillation. Large scale ocean events associated with the El Niņo/Southern Oscillation related signals are conveniently concentrated in the first {SSH} kernel {EOF} modes." }