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See detailReconstruction of incomplete oceanographic data sets using empirical orthogonal functions: application to the Adriatic Sea surface temperature
Alvera Azcarate, Aïda ULiege; Barth, Alexander ULiege; Rixen, Michel et al

in Ocean Modelling (2005), 9(4), 325-346

A method for the reconstruction of missing data based on an EOF decomposition has been applied to a large data set, a test case of Sea Surface Temperature satellite images of the Adriatic Sea. The EOF ... [more ▼]

A method for the reconstruction of missing data based on an EOF decomposition has been applied to a large data set, a test case of Sea Surface Temperature satellite images of the Adriatic Sea. The EOF decomposition is realised with a Lanczos method, which allows optimising computational time for large matrices. The results show that the reconstruction method leads to accurate reconstructions as well as a low cpu time when dealing with realistic cases. The method has been tested with different amounts of missing data, artificially adding clouds ranging from 40% to 80% of data loss, and then compared to the same data set with no missing data. A comparison with in situ data has also been made. These validation studies show that results are robust, even when the amount of missing data is very high. The reconstruction of the data from the Adriatic Sea shows realistic features and a reliable temperature distribution. In addition, the method is compared to an Optimal Interpolation reconstruction. The results obtained with both methods are very similar. The main difference is the computational time, which is reduced nearly 30 times with the method presented here. Once the reconstruction has been performed, the EOF decomposition is analysed to show the method's reliability, and a cold event on the Albanian coast is studied. The reconstructed data reflect the effect of wind on the Albanian coast, that led to a cold-water episode in this zone for a 6-day period. (c) 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailTwo-way nested model of mesoscale circulation features in the Ligurian Sea
Barth, Alexander ULiege; Alvera Azcarate, Aïda ULiege; Rixen, Michel et al

in Progress in Oceanography (2005), 66(2-4), 171-189

A coarse resolution primitive equation model of 1/4 degrees resolution is implemented covering the whole Mediterranea Sea. Within this grid a 1/20 degrees resolution model of the Liguro-Provencal basin ... [more ▼]

A coarse resolution primitive equation model of 1/4 degrees resolution is implemented covering the whole Mediterranea Sea. Within this grid a 1/20 degrees resolution model of the Liguro-Provencal basin and the northern part of the Tyrrhenian Sea is embedded. A third fine resolution model of 1/60 degrees is nested in the latter one and simulates the dynamics of the Ligurian Sea. Comparisons between one-way and two-way nesting in simulating the Northern Current (NC) are made. The properties of the Eastern and Western Corsican Current and the Northern Current are investigated with this nesting system. Special attention is given to the variability of the NC. Meanders and interactions with Winter Intermediate Water lenses are shown. Topographic features also lead to a highly variable NC. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailModelling eutrophication in mesotidal and macrotidal estuaries. The role of intertidal seaweeds.
Alvera Azcarate, Aïda ULiege; Ferreira, Joao; Nunes, Joao

in Estuarine Coastal & Shelf Science (2003), 57

The role of intertidal seaweeds in the primary production of mesotidal and macrotidal estuaries has been examined by means of a model, applied to the Tagus Estuary (Portugal). Special attention was paid ... [more ▼]

The role of intertidal seaweeds in the primary production of mesotidal and macrotidal estuaries has been examined by means of a model, applied to the Tagus Estuary (Portugal). Special attention was paid to the description of the underwater light climate in intertidal areas, and to the importance of the formation of tidal pools. Two approaches were compared for the simulation of suspended particulate matter (SPM) in the pool areas, using three algal species. The use of an erosion–deposition approach to simulate the distribution of SPM in tidal pools gives an increase in net primary productivity per unit area of between 130 and 1300%, when compared to the more conventional approach where the suspended matter in the overlying water in intertidal areas is considered identical to that in the channels. The upscaled erosion–deposition model was applied to tidal pool areas and combined with the more conventional model for other intertidal areas. Results show that annual carbon fixation by intertidal seaweeds in the estuary exceeds 13,500 t C yr−1, and accounts for 21% of the total carbon fixed by all primary producers. The corresponding nitrogen removal by seaweeds corresponds to the annual nutrient loading of a population of 490,000 inhabitants. [less ▲]

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See detailSolar Photocatalytic Destruction of p-Nitrophenol: A Pedagogical Use of Lab Wastes
Herrera-Melián, J. A.; Doña-Rodríguez, J. M.; Tello Rendón, E. et al

in Journal of Chemical Education (2001), 78(6), 775-777

In this article we propose the destruction of p-nitrophenol wastes obtained in a previous lab experiment, to generate a new lab experiment. The recommended destruction technique is solar TiO2 ... [more ▼]

In this article we propose the destruction of p-nitrophenol wastes obtained in a previous lab experiment, to generate a new lab experiment. The recommended destruction technique is solar TiO2-photocatalysis. When the effects of TiO2 and sunlight are tested separately, a slight decrease of p-nitrophenol is observed; but when TiO2 and sunlight are employed together p-nitrophenol disappears in 1 or 2 h. These experiments do not require sophisticated equipment or special lab training for the students. Groups of students tested different experimental conditions, such as the effect of different light intensities and sources (800-W UV-lamp, sunlight on sunny days, and sunlight on a cloudy day) or the addition of H2O2. p-Nitrophenol is degraded under the three light sources but at different rates. The addition of H2O2 to the TiO2-plus-sunlight system enhances p-nitrophenol degradation kinetics when compared with the TiO2 plus sunlight and H2O2 plus sunlight combinations. [less ▲]

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