Area de Medio Fisico

Madrid, Spain

Area de Medio Fisico

Madrid, Spain
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Aznar R.,Area de Medio Fisico | Aznar R.,Complutense University of Madrid | Sotillo M.G.,Area de Medio Fisico | Martin M.L.,University of Valladolid | And 2 more authors.
Atmospheric Research | Year: 2010

The knowledge of the Mediterranean basin hydrological cycle constitutes an issue with important implications in such a sensitive area. Precipitation is the best-known term of the Mediterranean budget, although large uncertainties remain. The major methodological drawback for its long-term assessment comes from the lack of suitable offshore observational data. This fact has driven towards the use of model-derived products to make estimations of precipitation and its variability over sea. In this scenario, satellite-based products arise as useful tools to assess the Mediterranean precipitation regime and, in spite of their known limitations, to evaluate different available model datasets. This work identifies existing similarities over the Mediterranean between five precipitation monthly means data sets derived from global reanalyses (NCEP and ERA40), regional hindcasts (HIPOCAS and ARPERA) and satellite-derived products (GPCP version 2) for the 22-year period encompassing 1979 through 2000.Whereas all the databases reproduce a latitudinal gradient, HIPOCAS, NCEP and ERA40 present precipitation values lower than GPCPv2, unlike ARPERA, which slightly overestimates the satellite-derived estimations. Time correlations and a wavelet analysis indicate a good degree of similarity between simulated and observational data sets regarding time evolution and variability.Considering the performed validations together with the limited time coverage of satellite-derived data, HIPOCAS, ARPERA and ERA40 products arise as adequate tools to carry out long-term climate precipitation studies over the Mediterranean basin and particularly over its offshore areas, unlike NCEP, which seems less consistent over this area. © 2010 Elsevier B.V.

Soto-Navarro J.,Area de Medio Fisico | Lorente P.,Area de Medio Fisico | Alvarez Fanjul E.,Area de Medio Fisico | Carlos Sanchez-Garrido J.,University of Malaga | Garcia-Lafuente J.,University of Malaga
Journal of Geophysical Research: Oceans | Year: 2016

Observations from a high frequency radar system and outputs from a high resolution operational ocean model working at the Strait of Gibraltar have been analyzed and compared during the period February 2013 to September 2014 in order to evaluate their capability to resolve the surface circulation of the region. The description of the mean circulation patterns has been statistically assessed, showing good agreement, particularly in the central region of the strait corresponding with the Atlantic Jet (AJ) stream, although some short scale features are not reproduced by the model. In the frequency domain very high concordance is observed. Tidal maps of diurnal and semidiurnal constituents are in good agreement with previous observations. The analysis of the model and radar response to the wind forcing reveals that the low resolution of the model wind-forcing field and its deeper superficial level smoothes the wind effect on the simulated currents. The first three EOF modes account for the 86% of model and radar variances. The coincidence between the observed and simulated patterns is very significant for the first two modes, which account for the mean velocity field and the latitudinal shifting of the AJ consequence of the flow-topography interaction. The third mode captures the wind-induced circulation, and greater discrepancies are found in this case. Results underline the complementary character of both systems: radar observations improve the model description, resolving short scale processes, while the model completes the radar information when the time or spatial coverage is poorer. © 2016. American Geophysical Union.

Sanchez-Garrido J.C.,University of Malaga | Garcia Lafuente J.,University of Malaga | Alvarez Fanjul E.,Area de Medio Fisico | Sotillo M.G.,Area de Medio Fisico | de los Santos F.J.,Autoridad Portuaria Bahia de Algeciras
Progress in Oceanography | Year: 2013

The stability of the mean state of the surface circulation of the Western Alboran Sea, characterized by a jet of Atlantic water (AJ) surrounding the Western Alboran Gyre (WAG), is investigated with a submesoscale-resolving operational ocean model. It is shown that this circulation state collapses through the interaction between the AJ-WAG system and a growing cyclonic eddy that arises close to the Spanish coast. This eddy develops as the WAG partially blocks the positive potential vorticity (PV) flux coming from the Strait of Gibraltar. It is found that tides increase the positive PV flux with respect to a non-tidal simulation, thus making the destabilization of the mean circulation state more likely. Atmospheric pressure driven flows are also shown to have the potential to destabilize the circulation by rising dramatically the PV flux within a time scale of some days. This provides an explanation as to why the circulation of the Western Alboran Sea exhibits more variability toward winter time, when meteorological fluctuations are enhanced. © 2013 Elsevier Ltd.

Albouy C.,IRD Montpellier | Guilhaumon F.,IRD Montpellier | Guilhaumon F.,University of Évora | Leprieur F.,IRD Montpellier | And 7 more authors.
Journal of Biogeography | Year: 2013

Aim: To forecast the potential effects of climate change in the Mediterranean Sea on the species richness and mean body size of coastal fish assemblages. Location: The Mediterranean Sea. Methods: Using an ensemble forecasting approach, we used species distribution modelling to project the potential distribution of 288 coastal fish species by the middle and end of the 21st century based on the IPCC A2 scenario implemented with the Mediterranean climatic model NEMOMED8. Results: A mean rise of 1.4 °C was projected for the Mediterranean Sea by the middle of the 21st century and 2.8 °C by the end of the 21st century. Projections for the end of the century suggest that: (1) 54 species are expected to lose their climatically suitable habitat, (2) species richness was predicted to decrease across 70.4% of the continental shelf area, especially in the western Mediterranean Sea and several parts of the Aegean Sea, and (3) mean fish body size would increase over 74.8% of the continental shelf area. Small-bodied species that are not targeted by either commercial or recreational fleets presented, on average, the highest predicted decrease in geographic range size. Main conclusions: Projected climate change in the Mediterranean Sea may have deleterious effects on coastal fish diversity, including a significant loss of climatically suitable habitat for endemic fish species. In addition, climate change may contribute to the loss of small and low trophic-level fishes, which may have ecosystem-wide impacts by reducing food supply to larger and higher trophic-level species. Fishing pressure is already selectively removing large-bodied species from marine ecosystems, and so fishing and climatic change might act in tandem to drive both direct and secondary extinctions. © 2012 Blackwell Publishing Ltd.

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