A case study of boundary layer ventilation by convection and coastal processes

It is often assumed that ventilation of the atmospheric boundary layer is weak in the absence of fronts, but is this always true? In this paper we investigate the processes responsible for ventilation of the atmospheric boundary layer during a nonfrontal day that occurred on 9 May 2005 using the UK Met Office Unified Model. Pollution sources are represented by the constant emission of a passive tracer everywhere over land. The ventilation processes observed include shallow convection, turbulent mixing followed by large-scale ascent, a sea breeze circulation and coastal outflow. Vertical distributions of tracer are validated qualitatively with AMPEP (Aircraft Measurement of chemical Processing Export fluxes of Pollutants over the UK) CO aircraft measurements and are shown to agree impressively well. Budget calculations of tracers are performed in order to determine the relative importance of these ventilation processes. Coastal outflow and the sea breeze circulation were found to ventilate 26% of the boundary layer tracer by sunset of which 2% was above 2 km. A combination of coastal outflow, the sea breeze circulation, turbulent mixing and large-scale ascent ventilated 46% of the boundary layer tracer, of which 10% was above 2 km. Finally, coastal outflow, the sea breeze circulation, turbulent mixing, large-scale ascent and shallow convection together ventilated 52% of the tracer into the free troposphere, of which 26% was above 2 km. Hence this study shows that significant ventilation of the boundary layer can occur in the absence of fronts (and thus during high-pressure events). Turbulent mixing and convection processes can double the amount of pollution ventilated from the boundary layer.

Coastal processes at Sea Bright to Ocean Township, New Jersey.

"August 1988."

Coastal processes study of the Oceanside, California, littoral cell : final report /

"August 1978."

Coastal processes and beach erosion /

Mode of access: Internet.

Study of the circulation processes in the northern Adriatic sea - coastal area and Venice lagoon inlets

This work is a detailed study of hydrodynamic processes in a defined area, the littoral in front of the Venice Lagoon and its inlets, which are complex morphological areas of interconnection. A finite element hydrodynamic model of the Venice Lagoon and the Adriatic Sea has been developed in order to study the coastal current patterns and the exchanges at the inlets of the Venice Lagoon. This is the first work in this area that tries to model the interaction dynamics, running together a model for the lagoon and the Adriatic Sea. First the barotropic processes near the inlets of the Venice Lagoon have been studied. Data from more than ten tide gauges displaced in the Adriatic Sea have been used in the calibration of the simulated water levels. To validate the model results, empirical flux data measured by ADCP probes installed inside the inlets of Lido and Malamocco have been used and the exchanges through the three inlets of the Venice Lagoon have been analyzed. The comparison between modelled and measured fluxes at the inlets outlined the efficiency of the model to reproduce both tide and wind induced water exchanges between the sea and the lagoon. As a second step, also small scale processes around the inlets that connect the Venice lagoon with the Northern Adriatic Sea have been investigated by means of 3D simulations. Maps of vorticity have been produced, considering the influence of tidal flows and wind stress in the area. A sensitivity analysis has been carried out to define the importance of the advection and of the baroclinic pressure gradients in the development of vortical processes seen along the littoral close to the inlets. Finally a comparison with real data measurements, surface velocity data from HF Radar near the Venice inlets, has been performed, which allows for a better understanding of the processes and their seasonal dynamics. The results outline the predominance of wind and tidal forcing in the coastal area. Wind forcing acts mainly on the mean coastal current inducing its detachment offshore during Sirocco events and an increase of littoral currents during Bora events. The Bora action is more homogeneous on the whole coastal area whereas the Sirocco strengthens its impact in the South, near Chioggia inlet. Tidal forcing at the inlets is mainly barotropic. The sensitivity analysis shows how advection is the main physical process responsible for the persistent vortical structures present along the littoral between the Venice Lagoon inlets. The comparison with measurements from HF Radar not only permitted a validation the model results, but also a description of different patterns in specific periods of the year. The success of the 2D and the 3D simulations on the reproduction both of the SSE, inside and outside the Venice Lagoon, of the tidal flow, through the lagoon inlets, and of the small scale phenomena, occurring along the littoral, indicates that the finite element approach is the most suitable tool for the investigation of coastal processes. For the first time, as shown by the flux modeling, the physical processes that drive the interaction between the two basins were reproduced.

Statistical assessment of annual patterns in coastal extreme wave conditions

[EN]The annual cycle in extreme values of significant wave height is examined by transforming the timing ofthe storm peaks in a circular variable, with the aim of taking advantage of the many tests devised to explore uniformity on the circle. The use of four different but complementary uniformity tests makes possible a robust assessment of the annual cycle statistical significance. Seasonality of storms in a long time series of significant wave heights, measured in a coastal zone, is examined. The presence of a seasonal pattem is statistically beyond doubt.

Coastal Impacts Around Guadiaro River Mouth (Spain)

The “Port of Sotogrande” Beach (San Roque, Cadiz, Spain) has suffered significant erosion and changes since the construction of the marina and port of Sotogrande (San Roque, Cadiz, Spain). This paper reviews the dynamical processes on Guadiaro front and establishes relationship between them. It sets from a comparative evolution of the Alboran Sea Coast outlets and bays since the Little Ice Age, which shows that the Guadiaro estuary has remained functional while all other Alboran fluvial estuaries silted to son. The study shows the evidences of the coastal impacts around the mouth, even further than mouth littoral barriers, of the port infrastructures; and it provides new elements to understand the dynamical processes on the mouth and surroundings as well. That should be fundamental for shore protection along the whole coastal stretch

Effects of Climate Change on Coastal Evolution

Climate determines coastal morphology through sea level and coastal processes, which are mainly steered by wind waves except in tidal inlets. They manage to erode coasts and transport their sediments if available. Coastal morphodynamic is so the result of its dialectic answers and it witness of wave direction and the whole climate through cyclone latitudes. This paper tries to approach the long term coastal processes and the trends of sedimentary coasts answer

Effects of climate change on coastal evolution

Climate determines coastal morphology through sea level and coastal processes, which are mainly steered by wind waves except in tidal inlets. They manage to erode coasts and transport their sediments if available. Coastal morphodynamic is so the result of its dialectic answers and it witness of wave direction and the whole climate through cyclone latitudes

Studies on Bio-Geochemistry, Bio-Optical Properties and Satellite Validation of Coastal Waters of South Eastern Arabian Sea

In situ methods used for water quality assessment have both physical and time constraints. Just a limited number of sampling points can be performed due to this, making it difficult to capture the range and variability of coastal processes and constituents. In addition, the mixing between fresh and oceanic water creates complex physical, chemical and biological environment that are difficult to understand, causing the existing measurement methodologies to have significant logistical, technical, and economic challenges and constraints. Remote sensing of ocean colour makes it possible to acquire information on the distribution of chlorophyll and other constituents over large areas of the oceans in short periods. There are many potential applications of ocean colour data. Satellite-derived products are a key data source to study the distribution pattern of organisms and nutrients (Guillaud et al. 2008) and fishery research (Pillai and Nair 2010; Solanki et al. 2001. Also, the study of spatial and temporal variability of phytoplankton blooms, red tide identification or harmful algal blooms monitoring (Sarangi et al. 2001; Sarangi et al. 2004; Sarangi et al. 2005; Bhagirathan et al., 2014), river plume or upwelling assessments (Doxaran et al. 2002; Sravanthi et al. 2013), global productivity analyses (Platt et al. 1988; Sathyendranath et al. 1995; IOCCG2006) and oil spill detection (Maianti et al. 2014). For remote sensing to be accurate in the complex coastal waters, it has to be validated with the in situ measured values. In this thesis an attempt to study, measure and validate the complex waters with the help of satellite data has been done. Monitoring of coastal ecosystem health of Arabian Sea in a synoptic way requires an intense, extensive and continuous monitoring of the water quality indicators. Phytoplankton determined from chl-a concentration, is considered as an indicator of the state of the coastal ecosystems. Currently, satellite sensors provide the most effective means for frequent, synoptic, water-quality observations over large areas and represent a potential tool to effectively assess chl-a concentration over coastal and oceanic waters; however, algorithms designed to estimate chl-a at global scales have been shown to be less accurate in Case 2 waters, due to the presence of water constituents other than phytoplankton which do not co-vary with the phytoplankton. The constituents of Arabian Sea coastal waters are region-specific because of the inherent variability of these optically-active substances affected by factors such as riverine input (e.g. suspended matter type and grain size, CDOM) and phytoplankton composition associated with seasonal changes.

Brazilian offshore wave climate based on NWW3 reanalysis

This paper provides a description of the wave climate off the Brazilian coast based on an eleven-year time series (Jan/1997-Dec/2007) obtained from the NWW3 operational model hindcast reanalysis. Information about wave climate in Brazilian waters is very scarce and mainly based on occasional short-term observations, the present analysis being the first covering such temporal and spatial scales. To define the wave climate, six sectors were defined and analyzed along the Brazilian shelf-break: South (W1), Southeast (W2), Central (W3), East (W4), Northeast (W5) and North (W6). W1, W2 and W3 wave regimes are determined by the South Atlantic High (SAH) and the passage of synoptic cold fronts; W4, W5 and W6 are controlled by the Intertropical Convergence Zone (ITCZ) and its meridional oscillation. The most energetic waves are from the S, generated by the strong winds associated to the passage of cold fronts, which mainly affect the southern region. Wave power presents a decrease in energy levels from south to north, with its annual variation showing that the winter months are the most energetic in W1 to W4, while in W5 and W6 the most energetic conditions occur during the austral summer. The information presented here provides boundary conditions for studies related to coastal processes, fundamental for a better understanding of the Brazilian coastal zone.

Standing wave bed forms at Plage de la Grande Roche, le Verdelet, Pléneuf-Val-André, Cote d’Armor (France)

Coastal Photograph by Hubert Chanson This photograph of standing wave bed forms was taken at very low tide. The tidal range was 10 m. The bed forms were located on the island of Le Verdelet, in a channel between Le Grande Jaune and Le Verdelet. It is likely that these standing wave bed forms were formed during transcritical shallow water flows at the end of ebb tide. The author’s watch is in the foreground for scale. (Coastal Photograph by Hubert Chanson, Division of Civil Engineering, the University of Queensland, Brisbane, Queensland 4072, Australia.)

Vulnerabilidad costera a múltiples agentes : aplicación al litoral catalán

El proyecto “Vulnerabilidad costera a múltiples agentes. Aplicación al litoral Catalán” tiene como objetivo general desarrollar y validar una metodología para evaluar cuantitativamente la vulnerabilidad de las costas sedimentarias a los principales procesos que rigen su comportamiento. Dentro de este contexto y durante un periodo de 6 meses se ha estado trabajando en el principal objetivo parcial del proyecto: el desarrollo de una serie de indicadores de vulnerabilidad costera a procesos físicos, más específicamente en la obtención de un índice de vulnerabilidad costera a temporales. Para ello se ha analizado la variabilidad espacial y temporal de la intensidad de los procesos costeros inducidos por temporales a lo largo de la costa Catalana, teniendo en cuenta únicamente la contribución de las características del oleaje. Se han integrado datos reales y simulados de oleaje de tres sitios distribuidos a lo largo del litoral Catalán para obtener las series temporales de intensidad de los tres procesos costeros derivados de la acción de temporales más relevantes (transporte de sedimentos, erosión e inundación). Los resultados muestran que no existen tendencias significativas en las series temporales de los procesos estudiados. Por otro lado, el análisis de las series de la media móvil de 5 años de las anomalías de dichos procesos refleja tendencias positivas significativas en el transporte de sedimentos y la erosión para las zonas norte y sur de la costa, y en la inundación para la zona sur. En relación a la variabilidad espacial, los resultados muestran que la zona sur es la más vulnerable a los procesos de erosión costera y transporte de sedimentos, mientras que la parte norte es la más vulnerable al proceso de inundación.

Sediment Budgeting Studies for the Kollam Coast

The Sediment budgeting studies are done to bring out the coastal processes at work, to understand the beach-innershelf sedimentary dynamics and to assess the stability of any coastal stretch. There is a dearth of such studies as far as the Indian coast is concerned. The Chavara coast of Kollam district, Kerala, is world famous for its rich heavy mineral resources. These mineral resources are being commercially mined by the Indian Rare Earths Ltd. (IREL) and Kerala Minerals and Metals Ltd. (KMML), two Public Sector Undertakings located in the area. The impact of mining on stability of the beach has been a point of debate among the local people as well as researchers. The coastal stretch of 22km length from Neendakara to Kayamkulam which is referred to as the Chavara coast. The tidal, wind driven and continental shelf currents, there could also be the contribution of coastal trapped waves and baroclinic flow associated with the plumes of fresh water coming from the estuaries. The main objectives of the study are the hydrodynamic processes and mechanism involved in the sediment movement along the Chavara coast, Identify the different sources and sinks of beach sand along the coast, Quantify the sediment input/output into/from the coast and assess the erosion/accretion scenario of the coast.

Strait dynamics of tropical tidal inlets

The dynamics and associated stability analysis of tidal inlets situated on the southwest coast of India, namely Andhakaranazhi (90 45 J OO JJN and 760 17 J 29 JJ E) and the other at Cochin harbour inlet (90 58 1 04 J1N and 760 14 1 50 1J E) have beenconducted. A detailed study on the inlet regime of Cochin barmouth (permanent in nature) was attempted so as to elucidate information on: (a) channel characteristics (b) tidal hydraulics and (c) stability of the inlet. In this connection, a naturally occurring seasonal sandbar formation at Andhakaranazhi, near Sherthallay, about 20 km south of Cochin inlet, was also chosen as a site ofstudy brought out conclusively the dynamical study. The aspects of ( 1) tidal influx/out flux (2) channel morphology (3) sedimentation regime and (4) stability and factors related to stability of these locations. The above aspects are supported by suitable mathematical formulations to describe the associated coastal processes, wherever applicable