http://hdl.handle.net/2117/1088 Tue, 21 May 2013 06:31:53 GMT 2013-05-21T06:31:53Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/14928 Title: Modelling shoreline sand waves: application to the coast of Namibia Authors: Falqués Serra, Albert; Van den Berg, Niels; Ribas Prats, Francesca; Caballeria Suriñach, Miquel Abstract: The SW coast of Africa (Namibia and part of Angola) features very long sandy beaches and a wave climate dominated by energetic swells from the SSW, therefore approaching the coast with a very high obliquity. Satellite images reveal that along that coast there are many shoreline sand waves with wavelengths ranging from 2 to 8 km. A more detailed study, including a Fourier analysis of the shoreline position, confirms a high spectral density concentration at these lengths scales. Also, it becomes apparent that at least some of the sand waves are dynamically active rather than being controlled by the geological setting. A morphodynamic model is used to test the hypothesis that these sand waves could emerge as free morphodynamic instabilities of the coastline due to the obliquity in wave incidence. It is found that the wave period, Tp, is crucial to establish the tendency to stability or instability, instability increasing for decreasing period, whilst there is some discrepancy in the observed periods. Model results for Tp = 7 s clearly show the tendency for the coast to develop free sand waves at 2 km wavelength within a few years, which migrate to the north at rates of 0.6-0.7 km/yr. For Tp = 8 s, instability is weaker and rather sensitive to other factors as the underlying bathymetry. In this case, the coast seems to be nearly at neutral stability so that sand waves originated from other mechanisms can propagate downdrift with little decay. http://hdl.handle.net/2117/14928 Falqués Serra, Albert; Van den Berg, Niels; Ribas Prats, Francesca; Caballeria Suriñach, Miquel no The SW coast of Africa (Namibia and part of Angola) features very long sandy beaches and a wave climate dominated by energetic swells from the SSW, therefore approaching the coast with a very high obliquity. Satellite images reveal that along that coast there are many shoreline sand waves with wavelengths ranging from 2 to 8 km. A more detailed study, including a Fourier analysis of the shoreline position, confirms a high spectral density concentration at these lengths scales. Also, it becomes apparent that at least some of the sand waves are dynamically active rather than being controlled by the geological setting. A morphodynamic model is used to test the hypothesis that these sand waves could emerge as free morphodynamic instabilities of the coastline due to the obliquity in wave incidence. It is found that the wave period, Tp, is crucial to establish the tendency to stability or instability, instability increasing for decreasing period, whilst there is some discrepancy in the observed periods. Model results for Tp = 7 s clearly show the tendency for the coast to develop free sand waves at 2 km wavelength within a few years, which migrate to the north at rates of 0.6-0.7 km/yr. For Tp = 8 s, instability is weaker and rather sensitive to other factors as the underlying bathymetry. In this case, the coast seems to be nearly at neutral stability so that sand waves originated from other mechanisms can propagate downdrift with little decay. http://hdl.handle.net/2117/19318 Title: Percolation experiments in complex fractal media Authors: Redondo Apraiz, José Manuel; Tarquis, Ana Maria; Cherubini, Claudia; Lopez Gonzalez-Nieto, Pilar; Vila, Teresa Thu, 16 May 2013 16:20:33 GMT http://hdl.handle.net/2117/19318 2013-05-16T16:20:33Z Redondo Apraiz, José Manuel; Tarquis, Ana Maria; Cherubini, Claudia; Lopez Gonzalez-Nieto, Pilar; Vila, Teresa no Percolation, Fractal, Karstic http://hdl.handle.net/2117/19317 Title: SAR measurements of coastal features in the NW Mediterranean Authors: Redondo Apraiz, José Manuel; Martínez Benjamín, Juan José; Díez Rilova, Margarita; Lopez Gonzalez-Nieto, Pilar Thu, 16 May 2013 16:15:04 GMT http://hdl.handle.net/2117/19317 2013-05-16T16:15:04Z Redondo Apraiz, José Manuel; Martínez Benjamín, Juan José; Díez Rilova, Margarita; Lopez Gonzalez-Nieto, Pilar no SAR, Coastal Features, Vortex http://hdl.handle.net/2117/18967 Title: The evolution and C, N and O yields of intermediate-mass Z = 10-5 stars in isolation and in close binary systems Authors: Gil Pons, Pilar; Doherty, Carolyn L.; Suda, T.; Campbell, Simon; Lau, H.; Mansouri Guilani, Shervin; Lattanzio, John Abstract: We have computed the evolution of Z = 10−5 stars of masses between 4 and 9 M , from their main sequence till the late TP-(S)AGB phase.We use a recent version of the Mount Stromlo Stellar Evolution code, in which molecular opacities include the effects of variable C/O abundances ratio, [1]. By computing hundreds (or thousands) of thermal pulses, we have been able either to remove the bulk of the stellar envelopes or to obtain stellar cores very close to MCh. Using [2] prescription for the mass loss rates the computed stars lose their envelopes before their cores reach MCh. This would forbid the occurrence of SN 1.5 for Z = 10−5 stars. Nevertheless the results by [3] suggest that the former prescription might overestimate the mass-loss rates. Therefore we have decreased the rates by [2]. For all the cases we present, even a decrease of one order of magnitude let the stellar cores reach MCh before the envelope is lost. Therefore the occurrence of SN1.5 at Z = 10 −5 and their potential contribution to the chemical evolution of the Universe should not be discarded. We consider the combined effects of the deep/corrosive 2 nd dredge-up and Roche Lobe Overflow (RLOF) during the E-AGB to help to constrain the contribution of massive Z = 10 −5 AGB stars to the CEMPs problem. Our results have implications for the chemical evolution of the Universe and might provide another piece for the puzzle of the CEMPs problem. Tue, 23 Apr 2013 14:39:01 GMT http://hdl.handle.net/2117/18967 2013-04-23T14:39:01Z Gil Pons, Pilar; Doherty, Carolyn L.; Suda, T.; Campbell, Simon; Lau, H.; Mansouri Guilani, Shervin; Lattanzio, John no We have computed the evolution of Z = 10−5 stars of masses between 4 and 9 M , from their main sequence till the late TP-(S)AGB phase.We use a recent version of the Mount Stromlo Stellar Evolution code, in which molecular opacities include the effects of variable C/O abundances ratio, [1]. By computing hundreds (or thousands) of thermal pulses, we have been able either to remove the bulk of the stellar envelopes or to obtain stellar cores very close to MCh. Using [2] prescription for the mass loss rates the computed stars lose their envelopes before their cores reach MCh. This would forbid the occurrence of SN 1.5 for Z = 10−5 stars. Nevertheless the results by [3] suggest that the former prescription might overestimate the mass-loss rates. Therefore we have decreased the rates by [2]. For all the cases we present, even a decrease of one order of magnitude let the stellar cores reach MCh before the envelope is lost. Therefore the occurrence of SN1.5 at Z = 10 −5 and their potential contribution to the chemical evolution of the Universe should not be discarded. We consider the combined effects of the deep/corrosive 2 nd dredge-up and Roche Lobe Overflow (RLOF) during the E-AGB to help to constrain the contribution of massive Z = 10 −5 AGB stars to the CEMPs problem. Our results have implications for the chemical evolution of the Universe and might provide another piece for the puzzle of the CEMPs problem. http://hdl.handle.net/2117/18917 Title: Frontogenesis in the meso-a and meso-ß scales in the Mediterranean basin: From cloud arch to cloud cells. Authors: Mazón Bueso, Jordi; Pino González, David Mon, 22 Apr 2013 12:01:45 GMT http://hdl.handle.net/2117/18917 2013-04-22T12:01:45Z Mazón Bueso, Jordi; Pino González, David no http://hdl.handle.net/2117/18916 Title: Nocturnal offshore precipitation near the coastline in the Mediterranean basin Authors: Mazón Bueso, Jordi; Pino González, David Mon, 22 Apr 2013 11:48:29 GMT http://hdl.handle.net/2117/18916 2013-04-22T11:48:29Z Mazón Bueso, Jordi; Pino González, David no http://hdl.handle.net/2117/18790 Title: The role of large sea-land temperature, the coastline shape and the SST in Authors: Mazón Bueso, Jordi; Pino González, David Mon, 15 Apr 2013 11:35:30 GMT http://hdl.handle.net/2117/18790 2013-04-15T11:35:30Z Mazón Bueso, Jordi; Pino González, David no http://hdl.handle.net/2117/18554 Title: Flash heat events: the case of 27th August 2010 in northeast of Iberian Authors: Mazón Bueso, Jordi; Pino González, David Wed, 03 Apr 2013 09:34:09 GMT http://hdl.handle.net/2117/18554 2013-04-03T09:34:09Z Mazón Bueso, Jordi; Pino González, David no http://hdl.handle.net/2117/18552 Title: Uncertainties in the CO2 budget associated to the diurnal variability of the boundary layer dynamics Authors: Pino González, David; Kaikkonen, Jukka-Pekka; Vilà-Guerau de Arellano, Jordi Wed, 03 Apr 2013 09:05:04 GMT http://hdl.handle.net/2117/18552 2013-04-03T09:05:04Z Pino González, David; Kaikkonen, Jukka-Pekka; Vilà-Guerau de Arellano, Jordi no http://hdl.handle.net/2117/18437 Title: Production of short-lived radioactive nuclei in Super Asymptotic Giant Branch stars Authors: Doherty, Carolyn L.; Lugaro, M.; Lau, H. H. B.; Siess, Lionel; Lattanzio, John; Gil Pons, Pilar Wed, 20 Mar 2013 12:17:20 GMT http://hdl.handle.net/2117/18437 2013-03-20T12:17:20Z Doherty, Carolyn L.; Lugaro, M.; Lau, H. H. B.; Siess, Lionel; Lattanzio, John; Gil Pons, Pilar no http://hdl.handle.net/2117/18428 Title: What determines the wavelength of self-organized shoreline sand waves? Authors: Falqués Serra, Albert; Van den Berg, Niels; Ribas Prats, Francesca; Caballeria, M Abstract: Shoreline undulations extending into the bathymetric contours with a length scale larger than that of the rhythmic surf zone bars are referred to as shoreline sand waves. Many observed undulations along sandy coasts display a wavelength in the order 1-7 km. Several models that are based on the hypothesis that sand waves emerge from a morphodynamic instability in case of very oblique wave incidence predict this range of wavelengths. Here we investigate the physical reasons for the wavelength selection and the main parametric trends of the wavelength in case of sand waves arising from such instability. It is shown that the existence of a minimum wavelength depends on an interplay between three factors affecting littoral drift: (A) the angle of wave fronts relative to local shoreline, which tends to cause maximum transport at the downdrift flank of the sand wave, (B) the refractive energy spreading which tends to cause maximum transport at the updrift flank and (C) wave focusing (de-focusing) by the capes (bays), which tends to cause maximum transport at the crest or slightly downdrift of it. Processes A and C cause decay of the sand waves while process B causes their growth. For low incidence angles, B is very weak so that a rectilinear shoreline is stable. For large angles and long sand waves, B is dominant and causes the growth of sand waves. For large angles and short sand waves C is dominant and the sand waves decay. Thus, wavelength selection depends on process C, which essentially depends on shoreline curvature. The growth rate of very long sand waves is weak because the alongshore gradients in sediment transport decrease with the wavelength. This is why there is an optimum or dominant wavelength. It is found that sand wave wavelength scales with λ0/β where λ0 is the water wave wavelength in deep water and β is the mean bed slope from shore to the wave base. Tue, 19 Mar 2013 19:22:41 GMT http://hdl.handle.net/2117/18428 2013-03-19T19:22:41Z Falqués Serra, Albert; Van den Berg, Niels; Ribas Prats, Francesca; Caballeria, M no Shoreline undulations extending into the bathymetric contours with a length scale larger than that of the rhythmic surf zone bars are referred to as shoreline sand waves. Many observed undulations along sandy coasts display a wavelength in the order 1-7 km. Several models that are based on the hypothesis that sand waves emerge from a morphodynamic instability in case of very oblique wave incidence predict this range of wavelengths. Here we investigate the physical reasons for the wavelength selection and the main parametric trends of the wavelength in case of sand waves arising from such instability. It is shown that the existence of a minimum wavelength depends on an interplay between three factors affecting littoral drift: (A) the angle of wave fronts relative to local shoreline, which tends to cause maximum transport at the downdrift flank of the sand wave, (B) the refractive energy spreading which tends to cause maximum transport at the updrift flank and (C) wave focusing (de-focusing) by the capes (bays), which tends to cause maximum transport at the crest or slightly downdrift of it. Processes A and C cause decay of the sand waves while process B causes their growth. For low incidence angles, B is very weak so that a rectilinear shoreline is stable. For large angles and long sand waves, B is dominant and causes the growth of sand waves. For large angles and short sand waves C is dominant and the sand waves decay. Thus, wavelength selection depends on process C, which essentially depends on shoreline curvature. The growth rate of very long sand waves is weak because the alongshore gradients in sediment transport decrease with the wavelength. This is why there is an optimum or dominant wavelength. It is found that sand wave wavelength scales with λ0/β where λ0 is the water wave wavelength in deep water and β is the mean bed slope from shore to the wave base. http://hdl.handle.net/2117/18427 Title: Intertidal finger bars at El Puntal spit, bay of Santander, Spain Authors: Garnier, Roland; Medina, Raúl; Pellón, Erica; Falqués Serra, Albert; Turki, Imen Abstract: We indentify the presence of an intertidal finger bar system in the swell-protected beaches of El Puntal Spit (Bay of Santander, Spain). The Horus video monitoring system allows us to perform a 2 year survey (June 2008- June 2010). We found that the bar system persists during the survey period with a wavelength of about 25 m and an oblique orientation with respect to the shore. Moreover, the analysis of the position of a particular bar (Bar 10) shows a movement characterized by a net migration to the west and a faster oscillation to the east or the west. Preliminary climate data analysis and morphological model results show that tide seems to be a forcing in the motion of the bars but also wind and waves generated by the wind probably affects the bar dynamics. Tue, 19 Mar 2013 18:54:44 GMT http://hdl.handle.net/2117/18427 2013-03-19T18:54:44Z Garnier, Roland; Medina, Raúl; Pellón, Erica; Falqués Serra, Albert; Turki, Imen no We indentify the presence of an intertidal finger bar system in the swell-protected beaches of El Puntal Spit (Bay of Santander, Spain). The Horus video monitoring system allows us to perform a 2 year survey (June 2008- June 2010). We found that the bar system persists during the survey period with a wavelength of about 25 m and an oblique orientation with respect to the shore. Moreover, the analysis of the position of a particular bar (Bar 10) shows a movement characterized by a net migration to the west and a faster oscillation to the east or the west. Preliminary climate data analysis and morphological model results show that tide seems to be a forcing in the motion of the bars but also wind and waves generated by the wind probably affects the bar dynamics. http://hdl.handle.net/2117/18398 Title: The Boundary Layer Late Afternoon and Sunset Turbulence 2011 field experiment (BLT) Authors: Lothon, Marie; Lohou, Fabienne; Durand, Pierre; Couvreux, Fleur; Hartogensis, Oskar; Legain, Dominique; Pardyjak, Erick; Pino González, David; Reuder, Joaquim; Vilà-Guerau de Arellano, Jordi Abstract: Growth of the CBL over land in the middle of the day has been extensively observed and relatively successfully modeled. However the late afternoon transition (LAT), like the morning transition, is difficult to observe and model due to turbulence intermittency and anisotropy, horizontal heterogeneity, and rapid time changes. There is a striking paucity of observations of the turbulence decay within the CBL, as well as a lack of realistic modeling studies. This motivated the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) 2011 field experiment, which aimed at enhancing observations of the LAT, so as to better understand the physical processes that control it, and elucidate the role of the LAT on mesoscale and turbulence scale motions, and on species transport. Tue, 19 Mar 2013 12:02:00 GMT http://hdl.handle.net/2117/18398 2013-03-19T12:02:00Z Lothon, Marie; Lohou, Fabienne; Durand, Pierre; Couvreux, Fleur; Hartogensis, Oskar; Legain, Dominique; Pardyjak, Erick; Pino González, David; Reuder, Joaquim; Vilà-Guerau de Arellano, Jordi no Growth of the CBL over land in the middle of the day has been extensively observed and relatively successfully modeled. However the late afternoon transition (LAT), like the morning transition, is difficult to observe and model due to turbulence intermittency and anisotropy, horizontal heterogeneity, and rapid time changes. There is a striking paucity of observations of the turbulence decay within the CBL, as well as a lack of realistic modeling studies. This motivated the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) 2011 field experiment, which aimed at enhancing observations of the LAT, so as to better understand the physical processes that control it, and elucidate the role of the LAT on mesoscale and turbulence scale motions, and on species transport. http://hdl.handle.net/2117/18364 Title: Boundary Layer Late Afternoon and Sunset Turbulence: the BLLAST 2011 experiment Authors: Pino González, David; Lothon, Marie; Lohou, Fabienne; Pardyjak, Erick; Reuder, Joaquim; Legain, Dominique; Durand, Pierre; Couvreux, Fleur; Vilà-Guerau de Arellano, Jordi Mon, 18 Mar 2013 11:58:13 GMT http://hdl.handle.net/2117/18364 2013-03-18T11:58:13Z Pino González, David; Lothon, Marie; Lohou, Fabienne; Pardyjak, Erick; Reuder, Joaquim; Legain, Dominique; Durand, Pierre; Couvreux, Fleur; Vilà-Guerau de Arellano, Jordi no http://hdl.handle.net/2117/17890 Title: Effect of surface rollers on the formation of crescentic bars: large angles of incidence Authors: Calvete Manrique, Daniel; Ribas Prats, Francesca; Swart, Huib E. de; Falqués Serra, Albert Abstract: The formation of crescentic bars is examined using a morphodynamic model based in linear stability analysis. The effect of surface rollers for off-normal wave conditions is examined. The effect of the rollers is to increase the e-folding times with increasing the angle of incidence. For angles large enough the formation of crescentic bars is even inhibit. The main effect of the rollers it be through hydrodynamics. The longitudinal changes in current produced by the rollers cause the maximum of sediment concentration to be shifted towards the coast with the final effect of prevent the formation of crecscentic bars. Tue, 19 Feb 2013 18:06:15 GMT http://hdl.handle.net/2117/17890 2013-02-19T18:06:15Z Calvete Manrique, Daniel; Ribas Prats, Francesca; Swart, Huib E. de; Falqués Serra, Albert no The formation of crescentic bars is examined using a morphodynamic model based in linear stability analysis. The effect of surface rollers for off-normal wave conditions is examined. The effect of the rollers is to increase the e-folding times with increasing the angle of incidence. For angles large enough the formation of crescentic bars is even inhibit. The main effect of the rollers it be through hydrodynamics. The longitudinal changes in current produced by the rollers cause the maximum of sediment concentration to be shifted towards the coast with the final effect of prevent the formation of crecscentic bars.