Uncertainty budget of Mediterranean storm surge projections for the XXIst Century

Trabajo presentado en la EGU General Assemby 2013, celebrada del 7 al 12 de abril de 2013 en Viena (Austria)Peer Reviewe

Regional marine climate scenarios in the NE Atlantic sector close to the Spanish shores

[EN] We present an overview of the changes expected during the 21st century in key marine parameters (sea surface temperature, sea surface salinity, sea level and waves) in the sector of the NE Atlantic Ocean close to the Spanish shores. Under the A1B scenario, open-sea surface temperatures would increase by 1°C to 1.5°C by 2050 as a consequence of global ocean warming. Near the continental margin, however, the global temperature rise would be counteracted by an enhancement of the seasonal upwelling. Sea surface salinity is likely to decrease in the future, mainly due to the advection of high-latitude fresher waters from ice melting. Mean sea level rise has been quantified as 15-20 cm by 2050, but two contributions not accounted for by our models must be added: the mass redistribution derived from changes in the large-scale circulation (which in the NE Atlantic may be as large as 15 cm in 2050 or 35 cm by 2100) and the increase in the ocean mass content due to the melting of continental ice (for which estimates are still uncertain). The meteorological tide shows very small changes, and therefore extreme sea levels would be higher in the 21st century, but mostly due to the increase in mean sea level, not to an increase in the storminess. The wave projections point towards slightly smaller significant wave heights, but the changes projected are of the same order as the natural variability.[ES]En este trabajo se presenta una visión de conjunto de los cambios esperados en el siglo XXI en los principales parámetros marinos (temperatura y salinidad superficiales, nivel del mar y oleaje) en el sector NE del Océano Atlántico más cercano a las costas españolas. Bajo el escenario A1B, se prevé que la temperatura superficial en mar abierto suba del orden de 1-1.5°C para el año 2050, como consecuencia del calentamiento global del océano. Cerca del margen continental, sin embargo, el aumento de la temperatura superficial podría ser contrarrestado por un aumento del afloramiento estacional. La salinidad superficial es probable que disminuya en el futuro, debido principalmente a la advección desde latitudes más altas de aguas provenientes de la fusión de hielos polares. El aumento del nivel del mar obtenido de los modelos se ha cuantificado en 15 a 20 cm para el año 2050, pero esa estima no incluye dos contribuciones adicionales que deben ser añadidas: la redistribución de masa derivada de los cambios en la circulación a gran escala (que en el Atlántico NE se ha estimado en unos 15 cm para 2050 i en 35 cm para 2100) y el aumento de masa debido a la fusión de hielos continentales (para el cual las estimas son todavía inciertas). La marea meteorológica muestra cambios muy pequeños, y por tanto el aumento de los niveles extremos del mar en el siglo XXI serán debidos principalmente al aumento del nivel medio, no a un aumento en la intensidad de las tormentas. Las proyecciones de oleaje apuntan a olas de altura significante ligeramente más pequeñas; de todos modos, los cambios proyectados son del mismo orden que la variabilidad natural.The computational work of this paper was carried out in the framework of two projects: VANIMEDAT-2 (CTM2009-10163-C02-01), funded by the Spanish Ministerio de Economía y Competitividad (MINECO) and the E-Plan of the Spanish Government; and ESCENARIOS, funded by the Agencia Estatal de Meteorología (AEMET). Some of the analysis and summary efforts were carried out in the framework of the subsequent project CLIMPACT (CGL2014-54246-C2-1-R), also funded by MINECO

Characterizing, modelling and understanding the climate variability of the deep water formation in the North-Western Mediterranean Sea

Observing, modelling and understanding the climate-scale variability of the deep water formation (DWF) in the North-Western Mediterranean Sea remains today very challenging. In this study, we first characterize the interannual variability of this phenomenon by a thorough reanalysis of observations in order to establish reference time series. These quantitative indicators include 31 observed years for the yearly maximum mixed layer depth over the period 1980–2013 and a detailed multi-indicator description of the period 2007–2013. Then a 1980–2013 hindcast simulation is performed with a fully-coupled regional climate system model including the high-resolution representation of the regional atmosphere, ocean, land-surface and rivers. The simulation reproduces quantitatively well the mean behaviour and the large interannual variability of the DWF phenomenon. The model shows convection deeper than 1000 m in 2/3 of the modelled winters, a mean DWF rate equal to 0.35 Sv with maximum values of 1.7 (resp. 1.6) Sv in 2013 (resp. 2005). Using the model results, the winter-integrated buoyancy loss over the Gulf of Lions is identified as the primary driving factor of the DWF interannual variability and explains, alone, around 50 % of its variance. It is itself explained by the occurrence of few stormy days during winter. At daily scale, the Atlantic ridge weather regime is identified as favourable to strong buoyancy losses and therefore DWF, whereas the positive phase of the North Atlantic oscillation is unfavourable. The driving role of the vertical stratification in autumn, a measure of the water column inhibition to mixing, has also been analyzed. Combining both driving factors allows to explain more than 70 % of the interannual variance of the phenomenon and in particular the occurrence of the five strongest convective years of the model (1981, 1999, 2005, 2009, 2013). The model simulates qualitatively well the trends in the deep waters (warming, saltening, increase in the dense water volume, increase in the bottom water density) despite an underestimation of the salinity and density trends. These deep trends come from a heat and salt accumulation during the 1980s and the 1990s in the surface and intermediate layers of the Gulf of Lions before being transferred stepwise towards the deep layers when very convective years occur in 1999 and later. The salinity increase in the near Atlantic Ocean surface layers seems to be the external forcing that finally leads to these deep trends. In the future, our results may allow to better understand the behaviour of the DWF phenomenon in Mediterranean Sea simulations in hindcast, forecast, reanalysis or future climate change scenario modes. The robustness of the obtained results must be however confirmed in multi-model studies

Improving sea level simulation in Mediterranean regional climate models

For now, the question about future sea level change in the Mediterranean remains a challenge. Previous climate modelling attempts to estimate future sea level change in the Mediterranean did not meet a consensus. The low resolution of CMIP-type models prevents an accurate representation of important small scales processes acting over the Mediterranean region. For this reason among others, the use of high resolution regional ocean modelling has been recommended in literature to address the question of ongoing and future Mediterranean sea level change in response to climate change or greenhouse gases emissions. Also, it has been shown that east Atlantic sea level variability is the dominant driver of the Mediterranean variability at interannual and interdecadal scales. However, up to now, long-term regional simulations of the Mediterranean Sea do not integrate the full sea level information from the Atlantic, which is a substantial shortcoming when analysing Mediterranean sea level response. In the present study we analyse different approaches followed by state-of-the-art regional climate models to simulate Mediterranean sea level variability. Additionally we present a new simulation which incorporates improved information of Atlantic sea level forcing at the lateral boundary. We evaluate the skills of the different simulations in the frame of long-term hindcast simulations spanning from 1980 to 2012 analysing sea level variability from seasonal to multidecadal scales. Results from the new simulation show a substantial improvement in the modelled Mediterranean sea level signal. This confirms that Mediterranean mean sea level is strongly influenced by the Atlantic conditions, and thus suggests that the quality of the information in the lateral boundary conditions (LBCs) is crucial for the good modelling of Mediterranean sea level. We also found that the regional differences inside the basin, that are induced by circulation changes, are model-dependent and thus not affected by the LBCs. Finally, we argue that a correct configuration of LBCs in the Atlantic should be used for future Mediterranean simulations, which cover hindcast period, but also for scenarios

Updating temperature and salinity mean values and trends in the Western Mediterranean: the RADMED project

Postprin

Vulnerabilidad de los puertos españoles ante el cambio climático. Vol. 1: Tendencias de variables físicas oceánicas y atmosféricas durante las últimas décadas y proyecciones para el siglo XXI

La presente publicación, el primer volumen de dos libros previstos sobre el tema, se centra en describir los resultados de los trabajos que se han realizado desde Puertos del Estado, el IMEDEA y AEMET para la caracterización de la evolución de las variables climáticas a lo largo del Siglo XXI. Los datos expuestos son el resultado de un enorme esfuerzo de computación numérica establecido a lo largo de 7 años en una serie de proyectos de investigación financiados por el Ministerio de Economía y Competitividad y por el Ministerio de Medio Ambiente, y su generación ha sido también posible gracias a la colaboración con multitud de centros internacionales de referencia, como MeteoFrance y Mercatorocean en Francia, o el National Oceanography Centre, en Reino Unido. Estos trabajos se enmarcan, además, en la estrategia española sobre cambio climático, y están coordinados con las actividades de la Oficina Española de Cambio Climático

Skills of different hydrographic networks in capturing changes in the Mediterranean Sea at climate scales

© Inter-Research 2015 . The skills of 5 observational networks are explored in the context of the monitoring of climate signals in the Mediterranean Sea. Namely we explore the capabilities of hydrographic surveys and ships of opportunity, of Argo buoys, of a (virtual) regularly distributed mooring network, of the present-day observational system (which makes use of the 3 kinds of observations) and of a targeted future system. The skills of each observational network are quantified as follows: first, the output of a realistic regional circulation model (considered here as the virtual truth) is sampled at the same time and location of the actual observations gathered by each observational network. An objective analysis scheme based on Optimal Statistical Interpolation is then applied to the pseudo-observations to obtain gridded products, which are compared to the model output in order to infer the capability of each sampling to capture the true fields. We do it for different periods (for 1962-2000 and for the whole 21st century) and for different parameters (temperature, salinity and the rate of deep water formation in the Western Mediterranean). Results indicate that the skills to reproduce large scale climatic signals depend on the depth and variable, ranging from >90% of explained monthly variance and <5% relative trend errors for the upper (0-100 m) and intermediate layer (100-400 m) temperature fields, to <60% of variance and 30% relative trend errors for the upper layer salinity field. When averaging temperature and salinity over the whole basin volume, both annual values and long term trends are properly captured by all the networks, though the deep water formation rate in the Western Mediterranean is largely overestimated. Conversely, regional features are missed by all the sampling networks, since none of them has an adequate spatial distribution to capture small scale processes.Peer Reviewe

Optimal spatio-temporal design of an hydrographic sampling aimed to monitor climate change in the Mediterranean Sea

Póster presentado en la 2012 General Assembly de la European Geosciences Union (EGU), celebrada del 22 al 27 de abril de 2012 en Viena (Austria)Peer Reviewe

Can we trust Mediterranean hydrographic data products (MEDAR, EN3, Ishii) for climate studies?

Trabajo presentado en la EGU General Assemby 2012, celebrada del 22 al 27 de septiembre de 2012 en Viena (Austria)Peer Reviewe