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2-D Empirical Mode Decomposition on the sphere, application to the spatial scales of surface temperature variations
1Department of Oceanography, University of Cape-Town, Cape Town, South Africa
2Civil Engineering, University of Kwazulu-Natal, Durban, South Africa
Abstract. The Empirical Mode Decomposition (EMD) is applied here in two dimensions over the sphere to demonstrate its potential as a data-driven method of separating the different scales of spatial variability in a geophysical (climatological/meteorological) field. After a brief description of the basics of the EMD in 1 then 2 dimensions, the principles of its application on the sphere are explained, in particular via the use of a zonal equal area partitioning. The EMD is first applied to a artificial dataset, demonstrating its capability in extracting the different (known) scales embedded in the field. The decomposition is then applied to a global mean surface temperature dataset, and we show qualitatively that it extracts successively larger scales of temperature variations related for example to the topographic and large-scale, solar radiation forcing. We propose that EMD can be used as a global data-adaptative filter, which will be useful in analyzing geophysical phenomena that arise as the result of forcings at multiple spatial scales.
Discussion Paper (PDF, 5157 KB) Interactive Discussion (Closed, 5 Comments) Final Revised Paper (HESS)
Citation: Fauchereau, N., Sinclair, S., and Pegram, G.: 2-D Empirical Mode Decomposition on the sphere, application to the spatial scales of surface temperature variations, Hydrol. Earth Syst. Sci. Discuss., 5, 405-435, 2008. Bibtex EndNote Reference Manager
