Forecast verification of a 3D model of the Mediterranean Sea. The use of discrete wavelet transforms and EOFs in the skill assessment of spatial forecasts
Alvera-Azcarate, A.; Barth, A.; Ben Bouallegue, Z.; Rixen, M.; Beckers, J.-M. (2007). Forecast verification of a 3D model of the Mediterranean Sea. The use of discrete wavelet transforms and EOFs in the skill assessment of spatial forecasts. J. Mar. Syst. 65(1-4): 460-483. https://dx.doi.org/10.1016/j.jmarsys.2005.09.015 In: Journal of Marine Systems. Elsevier: Tokyo; Oxford; New York; Amsterdam. ISSN 0924-7963; e-ISSN 1879-1573, more Also appears in:Desaubies, Y.; Rixen, M.; Beckers, J.-M. (2007). Marine environmental monitoring and prediction. Selected papers from the 36th International Liège Colloquium on Ocean Dynamics, May 3-7, 2004. Journal of Marine Systems, 65(1-4). Elsevier: Amsterdam. 588 pp., more |  |
| Keyword | | | Author keywords | forecast verification; spatio-temporal analysis; wavelets; EOFs; |
| Authors | | Top | - Alvera-Azcarate, A.
- Barth, A., more
- Ben Bouallegue, Z., more
| - Rixen, M.
- Beckers, J.-M., more
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| Abstract | The quality assessment of a nested model system of the Mediterranean Sea is realised. The model has two zooms in the Provencal Basin and in the Ligurian Sea, realised with a two-way nesting approach. The experiment lasts for nine weeks, and at each week sea surface temperature (SST) and sea level anomaly are assimilated. The quality assessment of the surface temperature is done in a spatio-temporal approach, to take into account the high complexity of the SST distribution. We focus on the multi-scale nature of oceanic processes using two powerful tools for spatio-temporal analysis, wavelets and Empirical Orthogonal Functions (EOFs). We apply two-dimensional wavelets to decompose the high-resolution model and observed SST into different spatial scales. The Ligurian Sea model results are compared to observations at each of those spatial scales, with special attention on how the assimilation affects the model behaviour. We also use EOFs to assess the similarities between the Mediterranean Sea model and the observed SST. The results show that the assimilation mainly affects the model large-scale features, whereas the small scales show little or no improvement and sometimes, even a decrease in their skill. The multiresolution analysis reveals the connection between large- and small-scale errors, and how the choice of the maximum correlation length of the assimilation scheme affects the distribution of the model error among the different spatial scales. |
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