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We investigate the role of the ocean's heat engine in setting horizontal circulation using a numerical model of the Caspian Sea. The Caspian Sea can be seen as a virtual laboratory - a compromise between realistic global models which are hampered by long equilibration times and idealized basin geometry models which are not constrained by observations. We find that increases in vertical mixing drive stronger thermally direct overturning and consequent conversion of available potential to kinetic energy. Numerical solutions with water mass structures closest to observations overturn 0.02 − 0.04 x 106m3/s(Sv) representing the first estimate of Caspian Sea overturning. Our results also suggest that the overturning is thermally-forced increasing in intensity with increasing vertical diffusivity. Finally, stronger thermally direct overturning is associated with a stronger horizontal circulation in the Caspian Sea. This suggests the ocean's heat engine can strongly impact broader horizontal circulations in the ocean.

Genetic variants of the glutamate activated N-methyl-D-aspartate (NMDA) receptor (NMDAR) subunit GluN2A are associated with the hyperexcitable states manifested by epileptic seizures and interictal discharges in patients with disorders of the epilepsy-aphasia spectrum (EAS). The variants found in sporadic cases and families are of different types and include microdeletions encompassing the corresponding GRIN2A gene as well as nonsense, splice-site and missense GRIN2A defects. They are located at different functional domains of GluN2A and no clear genotype-phenotype correlation has emerged yet. Moreover, GluN2A variants may be associated with phenotypic pleiotropy. Deciphering the consequences of pathogenic GRIN2A variants would surely help in better understanding of the underlying mechanisms. This emphasizes the need for functional studies to unravel the basic functional properties of each specific NMDAR variant. In the present study, we have used patch-clamp recordings to evaluate kinetic changes of mutant NMDARs reconstituted after co-transfection of cultured cells with the appropriate expression vectors. Three previously identified missense variants found in patients or families with disorders of the EAS and situated in the N-terminal domain (p.Ile184Ser) or in the ligand-binding domain (p.Arg518His and p.Ala716Thr) of GluN2A were studied in both the homozygous and heterozygous conditions. Relative surface expression and current amplitude were significantly reduced for NMDARs composed of mutant p.Ile184Ser and p.Arg518His, but not p.Ala716His, as compared with wild-type (WT) NMDARs. Amplitude of whole-cell currents was still drastically decreased when WT and mutant p.Arg518His-GluN2A subunits were co-expressed, suggesting a dominant-negative mechanism. Activation times were significantly decreased in both homozygous and heterozygous conditions for the two p.Ile184Ser and p.Arg518His variants, but not for p.Ala716His. Deactivation also significantly increased for p.Ile184Ser variant in the homozygous but not the heterozygous state while it was increased for p.Arg518His in both states. Our data indicate that p.Ile184Ser and p.Arg518His GluN2A variants both impacted on NMDAR function, albeit differently, whereas p.Ala716His did not significantly influence NMDAR kinetics, hence partly questioning its direct and strong pathogenic role. This study brings new insights into the functional impact that GRIN2A variants might have on NMDAR kinetics, and provides a mechanistic explanation for the neurological manifestations seen in the corresponding human spectrum of disorders., published version, peerReviewed

128p DHA/NEC 2014 12 a 16 de maio

A Ria Formosa é um sistema lagunar localizado no Sul de Portugal, sendo um ecossistema de elevada produtividade biológica e diversidade ecológica. A caracterização dos padrões de circulação e de transporte na Ria Formosa, em particular as trocas com o oceano adjacente através das barras, a influência das marés e de outros forçamentos ambientais, são essenciais para a compreensão da dinâmica deste ecossistema. Os dados adquiridos nas campanhas do projecto COALA permitiram validar o modelo hidrodinâmico SELFE, que mostrou uma boa capacidade de representar os padrões de circulação da Ria. A circulação e o transporte foram analisados com o modelo lagrangeano VELApart, simulando cenários sujeitos a diferentes forçamentos (vento, batimetria e caudais de água doce). Os resultados sugerem uma influência significativa da direcção do vento e da batimetria na quantidade de partículas exportadas para o exterior a escalas temporais curtas, a qual depende da barra de origem das partículas. Existe também uma influência do vento e da batimetria nas barras pelas quais as partículas são exportadas e na sua distribuição espacial. Estes resultados, complementados com os dados obtidos nas campanhas do projecto COALA, contribuirão para melhorar o conhecimento da dinâmica de trocas entre a Ria e a zona costeira adjacente. 16pp Seminário / 12º Congresso da Água DHA/NEC

This paper presents a review of the processes controlling wave-dominated inlets, based on several studies conducted at two inlets located on the West Coast of Portugal. Once the observed hydrodynamics and morphological changes are reasonably simulated, numerical experiments are performed to explain the development of the inlet during fair weather conditions and its shoaling and closure during winter storms. The former behaviour is explained by a tidal distortion that promotes ebb-dominance while the latter is explained by the combination of several wave-related processes: (1) the “bulldozer effect” due to the shore-normal component of wave forces; (2) the presence of lateral barotropic pressure gradients, accelerating longshore flows towards the inlet; (3) wave blocking during the ebb and (4) a rise in mean sea level in late autumn. Recent results also suggest that infragravity waves may play a major role. 10p DHA/NEC 2013 24 a 28 de junho

The development of the deep Southern Ocean winter mixed layer in the climate models participating in the fifth Coupled Models Intercomparison Project (CMIP5) is assessed. The deep winter convection regions are key to the ventilation of the ocean interior, and changes in their properties have been related to climate change in numerous studies. Their simulation in climate models is consistently too shallow, too light and shifted equatorward compared to observations. The shallow bias is mostly associated with an excess annual-mean freshwater input at the sea surface that over-stratifies the surface layer and prevents deep convection from developing in winter. In contrast, modeled future changes are mostly associated with a reduced heat loss in winter that leads to even shallower winter mixed layers. The mixed layers shallow most strongly in the Pacific basin under future scenarios, and this is associated with a reduction of the ventilated water volume in the interior. We find a strong state dependency for the future change of mixed-layer depth, with larger future shallowing being simulated by models with larger historical mixed-layer depths. Given that most models are biased shallow, we expect that most CMIP5 climate models might underestimate the future winter mixed-layer shallowing, with important implications for the sequestration of heat, and gases such as carbon dioxide, and therefore for climate.

The western sector of Ria Formosa, a lagoon system in the south of Portugal, represents approximately 90% of the total tidal prism of the lagoon and includes three inlets. Two sets of field campaigns to characterize the hydrodynamics of this sector in neap and spring tide conditions were conducted in the autumn of 2011 and spring 2012. The main findings related to the inlets hydrodynamics and water exchanges between the lagoon and the ocean along semi-diurnal tidal cycles are presented. To estimate the relative contribution of the three inlets to the water exchanges between Ria Formosa and the ocean, discharges were evaluated hourly along complete neap and spring semi-diurnal tidal cycles and the tidal prisms computed. In addition, two sea level time series measured in Faro-Olhão inlet and Faro commercial pier were harmonically analyzed. The results were compared with previous studies and used to validate the ELCIRC hydrodynamic model. This model provided additional information about the circulation and tidal prisms and distortion inside the western Ria Formosa. This study confirmed the Faro-Olhão inlet as the main inlet in terms of contribution for the total tidal prism. It is shown that the Ancão inlet lost hydraulic efficiency, contributing less than 6% to the total tidal prism in all situations and the Armona inlet gained efficiency in spring tide and lost efficiency in neap tide. Moreover, the Faro-Olhão inlet exhibits flood prisms higher than ebb prisms under neap and spring tides, suggesting a residual circulation towards the Ancão and Armona inlets. 2011-2016pp SI 65 DHA/NEC Journal of Coastal Research

Wave-current interactions play a major role in the dynamics of shallow tidal inlets. This study investigates these interactions at a natural inlet, with a strong focus on current-induced changes on wave propagation. The analysis of hydrodynamic data collected at the Albufeira lagoon, Portugal, revealed spatiotemporal variations of water levels and wave heights along the inlet, attributed to wave-current interaction processes. We compared the simulations of a coupled wave-circulation modeling system, computed with and without waves, and propagated with and without current feedback. The wave-induced setup inside the lagoon represented 7%–15% of the offshore significant wave height. The accuracy of the wave’s predictions improved when current feedback was included. During ebb, the currents increased the wave height at the mouth of the inlet (up to 20%) and decreased the wave height in the inlet (up to 40%), due to current-induced refraction, steepness dissipation, and partial blocking. During flood, the currents decreased the wave height in the inlet (up to 10%) and increased the wave height at the exterior parts of the ebb shoal (up to 10%), due to current-induced refraction. These effects significantly attenuate seaward sediment fluxes during ebb and contribute to the sediment accretion in the inlet. 1587-1605pp Volume 118 DHA/NEC JOURNAL OF GEOPHYSICAL RESEARCH: OCEANS

The representation of the Antarctic Circumpolar Current (ACC) in the fifth Coupled Models Intercomparison Project (CMIP5) is generally improved over CMIP3. The range of modeled transports in the historical (1976–2006) scenario is reduced (90–264 Sv) compared with CMIP3 (33–337 Sv) with a mean of 155 ± 51 Sv. The large intermodel range is associated with significant differences in the ACC density structure. The ACC position is accurately represented at most longitudes, with a small (1.27°) standard deviation in mean latitude. The westerly wind jet driving the ACC is biased too strong and too far north on average. Unlike CMIP3 there is no correlation between modeled ACC latitude and the position of the westerly wind jet. Under future climate forcing scenarios (2070–2099 mean) the modeled ACC transport changes by between −26 to +17 Sv and the ACC shifts polewards (equatorwards) in models where the transport increases (decreases). There is no significant correlation between the ACC position change and that of the westerly wind jet, which shifts polewards and strengthens. The subtropical gyres strengthen and expand southwards, while the change in subpolar gyre area varies between models. An increase in subpolar gyre area corresponds with a decreases in ACC transport and an equatorward shift in the ACC position, and vice versa for a contraction of the gyre area. There is a general decrease in density in the upper 1000 m, particularly equatorwards of the ACC core.

The wave regime has a strong influence on the sediment transport in coastal systems. Modifications in wave regime induced by climate changes can influence the sediment dynamics of those coastal systems. To access wave regime changes it is crucial to analyse the future modifications in the wave height, period and direction. This work aims to analyse the influence of a future wave regime in the sediment budget of a coastal lagoon inlet and at the nearshore adjacent coast. To achieve this goal a morphodynamic modelling system was used, forced by present and future waves, corresponding to a typical year of present and future wave climates. A methodology to determine a typical year of each climate was developed based on the determination of correlation coefficients between each climate and corresponding year data. The comparison between present and future wave climates evidences that wave period and height are in general similar for both climates, and confirms the anticlockwise rotation of waves in the future. The morphodynamic simulations revealed analogous results for both wave climates, resulting in similar patterns for the residual sediment fluxes, but slightly more intense in the present. The consequent bathymetric changes show that the deposition trend presently observed offshore the inlet tends to increase for future waves climate. The transport budgets were also analysed for both wave regimes, evidencing that the alongshore transport slightly decreases (~1%) for future waves. 1-12pp DHA/NEC 2012

O projeto COALA tem como objetivo compreender a dinâmica dos nutrientes, clorofilaa e matéria em suspensão no setor oeste da Ria Formosa. Para isso é importante estudar e caracterizar a hidrodinâmica bastante complexa da Ria Formosa. As primeiras campanhas do projeto COALA foram realizadas no Outono de 2011. Incluiram a colocação de dois sensores de pressão, um na barra de FaroOlhão e o outro no cais comercial de Faro, durante um período de 2 meses, para estudar a variação do nível do mar em função da maré e outros fenómenos de baixa frequência. A análise dos dados de nível do mar permitiu caracterizar dois ciclos mensais de maré completos, proporcionando informação acerca da propagação e distorção da maré ao longo do canal de Faro. Estes dados permitiram validar o modelo hidrodinâmico ELCIRC, cuja utilização vai ajudar a caracterizar as correntes, o prisma e a distorção da maré na ria Formosa. 185-188pp DHA/NEC

We use a nonlinear morphodynamic model to demonstrate that the presence of a single persistent offshore bathymetric anomaly strongly affects the formation, nonlinear evolution and saturation of surf zone rip channels. In the case of an offshore bump or trough and waves with oblique incidence, a rip channel shoreward of the anomaly is enforced by the more seaward alongshore variability in depth. The degree of rip channel enforcement is controlled by the strength of the rotational nature of surf zone rip current circulations, which is, in turn, driven by differential broken wave energy dissipation induced by wave refraction across the offshore bathymetric anomaly. The alongshore location of this forced rip channel is more stable with increasing offshore anomaly amplitude, decreasing offshore wave obliquity and decreasing bathymetric anomaly distance to the shore. Simulations show that rip channel behavior downdrift and updrift of the offshore perturbation are different. In our numerical experiments, downdrift rip channels have systematically larger alongshore scales, smaller alongshore migration rates and more erosive megacusps than those updrift. Rip channels therefore self-organize into patterns of different alongshore scales and migration rates as a result of an alongshore perturbation in the wave forcing enforced by wave refraction across an offshore bathymetric anomaly. These simulations are qualitatively corroborated by video observations of sandbar behavior during a down-state sequence at a site with a persistent offshore trough.

This study aims to hindcast and analyze the storm surge associated with Xynthia, a mid-latitude depression that severely hit the French central part of the Bay of Biscay on the 27–28th of February 2010. The main losses in human lives and damages were caused by the associated storm surge, which locally exceeded 1.5 m and peaked at the same time as a high spring tide, causing the flooding of low-lying coasts. A new storm surge modeling system was developed, based on the unstructured-grid circulation model SELFE and the spectral wave model WaveWatchIII. The modeling system was implemented over the North-East Atlantic Ocean and resulted in tidal and wave predictions with errors of the order of 3% and 15%, respectively. The storm surge associated with Xynthia was also well predicted along the Bay of Biscay, with only a slight underestimation of the surge peak by 3–8%. Numerical experiments were then performed to analyze the physical processes controlling the development of the storm surge and revealed firstly that the wind caused most of the water level anomaly through an Ekman setup process. The comparison between a wave-dependant and a quadratic parameterization to compute wind stress showed that the storm surge was strongly amplified by the presence of steep and young wind-waves, related to their rapid development in the restricted fetch of the Bay of Biscay. In the central part of the Bay of Biscay, both observed and predicted water level anomalies at landfall displayed 6 h oscillations, with amplitudes of up to 0.2 m (10–20% of the surge peak). An analytical shelf resonance model and numerical experiments demonstrated that the period of the observed oscillations corresponds to the resonant mode of the continental shelf in the central part of the Bay of Biscay. It is concluded that these oscillations originate from the interactions between the water level perturbation and the continental shelf and this phenomenon is expected to be relevant at other places along the world’s coastlines. 13-30pp 42/1 DHA/NEC Ocean Modelling

1pp DHA/NEC 2011 22-25 agosto

3 2 pp DHA/NEC 2011 3 - 4 de Fevereiro

1 3 pp DHA/NEC 2011 3 - 4 de Fevereiro

2 3 pp DHA/NEC 2011 3 - 4 de Fevereiro