Ocean Science www.ocean-sci.net 1812-0784 1812-0792 5 4 2009 10.5194/os-5-475-2009 http://www.ocean-sci.net/5/475/2009/ http://www.ocean-sci.net/5/475/2009/os-5-475-2009.html http://www.ocean-sci.net/5/475/2009/os-5-475-2009.pdf 475 485 2009-10-28 Enhancing temporal correlations in EOF expansions for the reconstruction of missing data using DINEOF A. Alvera-Azcárate a.alvera@ulg.ac.be A. Barth D. Sirjacobs J.-M. Beckers AGO-GHER, University of Liège, Allée du Six Août, 17, Sart Tilman, Liège, 4000, Belgium National Fund for Scientific Research, FNRS-FRS, Belgium Department of Life Sciences, University of Liège, Sart Tilman, Liège, 4000, Belgium DINEOF (Data Interpolating Empirical Orthogonal Functions) is an EOF-based technique for the reconstruction of missing data in geophysical fields, such as those produced by clouds in sea surface temperature satellite images. A technique to reduce spurious time variability in DINEOF reconstructions is presented. The reconstruction of these images within a long time series using DINEOF can lead to large discontinuities in the reconstruction. Filtering the temporal covariance matrix allows to reduce this spurious variability and therefore more realistic reconstructions are obtained. The approach is tested in a three years sea surface temperature data set over the Black Sea. The effect of the filter in the temporal EOFs is presented, as well as some examples of the improvement achieved with the filtering in the SST reconstruction, both compared to the DINEOF approach without filtering. Alvera-Azcárate, A., Barth, A., Rixen, M., and Beckers, J M.: Reconstruction of incomplete oceanographic data sets using Empirical Orthogonal Functions. Application to the Adriatic Sea surface temperature, Ocean Modelling., 9, 325–346, 2005. Alvera-Azcárate, A., Barth, A., Beckers, J M., and Weisberg, R H.: Multivariate Reconstruction of Missing Data in Sea Surface Temperature, Chlorophyll and Wind Satellite Fields, J. Geophys. Res., 112, C03008, doi:10.1029/2006JC003660, 2007. Beckers, J.-M. and Rixen, M.: EOF calculations and data filling from incomplete oceanographic data sets, Journal of Atmospheric and Oceanic Technology, 20, 1839–1856, 2003. Beckers, J.-M., Barth, A., and Alvera-Azcárate, A.: DINEOF reconstruction of clouded images including error maps. Application to the Sea Surface Temperature around Corsican Island, Ocean Sci., 2, 183–199, 2006. Castro, S L., Wick, G A., Jackson, D L., and Emery, W J.: Error characterization of infrared and microwave satellite sea surface temperature products for merging and analysis, J. Geophys. Res., 113, C03010, doi:10.1029/2006JC003829, 2008. Gawarkiewicz, G., Korotaev, G., Stanichny, S., Repetin, L., and Soloviev, D.: Synoptic upwelling and cross-shelf transport processes along the Crimean coast of the Black Sea, Cont. Shelf Res., 19, 977–1005, 1999. Gentemann, C L., Wentz, F J., Mears, C A., and Smith, D K.: In situ validation of Tropical Rainfall Measuring Mission microwave sea surface temperatures, J. Geophys. Res., 109, C04021, doi:10.1029/2003JC002092, 2004. Kosarev, A N., Kostianoy, A G., and Shiganova, T A.: The Black Sea Environment, vol 5Q of The Handbook of Environmental Chemistry\/, chap The Sea of Azov, 63–89, Springer, 2008. Kumar, A., Minnet, P., Podesta, G., Evans, R., and Kilpatrick, K.: Analysis of Pathfinder SST algorithm for global and regional conditions, Proceedings of the Indian Academy of Sciences (Earth and Planetary Sciences), 109, 395–405, 2000. Lehoucq, R B., Sorensen, D C., and Yang, C.: ARPACK user's guide: solution of large scale eigenvalue problems with implicity restarted Arnoldi methods, 1–152, prefixhttp://www.caam.rice.edu/software/ARPACK/, 1997. Marullo, S., Buongiorno~Nardelli, B., Guarracino, M., and Santoleri, R.: Observing the Mediterranean Sea from space: 21 years of Pathfinder-AVHRR sea surface temperatures (1985 to 2005): re-analysis and validation, Ocean Sci., 3, 299–310, 2007. McClain, E., Pichel, W., and Walton, C.: Comparative performance of AVHRR-based multichannel sea surface temperatures, J. Geophys. Res., 90(C6), 11587–11601, 1985. Sur, H L. and Ilyin, Y P.: Evolution of satellite derived mesoscale thermal patterns in the Black Sea, Prog. Oceanogr., 39, 109–151, 1997. Sur, H L., Özsoy, E., Ilyin, Y P., and Ünlüata, U.: Coastal/deep ocean interactions in the Black Sea and their ecological/environmental impacts, J. Marine Syst., 7, 293–320, 1996. Toumazou, V. and Cretaux, J F.: Using a Lanczos eigensolver in the computation of Empirical Orthogonal Functions, Mon. Weather Rev., 129, 1243–1250, 2001.