Effects of friction and surface tide angle of incidence on the coastal generation of internal tides

For the generation of internal waves by long surface waves, the normal-mode equations and solutions that satisfy the boundary conditions in a two-layer system are found analytically. Frictional effects decrease the amplitude of an internal wave over the shelf, changing it from a standing wave to a wave that progresses coastward and decreases the interference on the amplitude of the offshore progressive wave traveling seaward. Model studies, using a two-layer system of fresh water and saline water in a 9.9-m-long channel, gave favorable results relative to the theoretical results

Prospects for seasonal forecasting of iceberg distributions in the North Atlantic

An efficient approach to ocean–iceberg modelling provides a means for assessing prospects for seasonal forecasting of iceberg distributions in the northwest Atlantic, where icebergs present a hazard to mariners each spring. The stand-alone surface (SAS) module that is part of the Nucleus for European Modelling of the Ocean (NEMO) is coupled with the NEMO iceberg module (ICB) in a “SAS-ICB” configuration with horizontal resolution of 0.25°. Iceberg conditions are investigated for three recent years, 2013–2015, characterized by widely varying iceberg distributions. The relative simplicity of SAS-ICB facilitates efficient investigation of sensitivity to iceberg fluxes and prevailing environmental conditions. SAS-ICB is provided with daily surface ocean analysis fields from the global Forecasting Ocean Assimilation Model (FOAM) of the Met Office. Surface currents, temperatures and height together determine iceberg advection and melting rates. Iceberg drift is further governed by surface winds, which are updated every 3 h. The flux of icebergs from the Greenland ice sheet is determined from engineering control theory and specified as an upstream flux in the vicinity of Davis Strait for January or February. Simulated iceberg distributions are evaluated alongside observations reported and archived by the International Ice Patrol. The best agreement with observations is obtained when variability in both upstream iceberg flux and oceanographic/atmospheric conditions is taken into account. Including interactive icebergs in an ocean–atmosphere model with sufficient seasonal forecast skill, and provided with accurate winter iceberg fluxes, it is concluded that seasonal forecasts of spring/summer iceberg conditions for the northwest Atlantic are now a realistic prospect

Late Winter Biogeochemical Conditions Under Sea Ice in the Canadian High Arctic

With the Arctic summer sea-ice extent in decline, questions are arising as to how changes in sea-ice dynamics might affect biogeochemical cycling and phenomena such as carbon dioxide (CO2) uptake and ocean acidification. Recent field research in these areas has concentrated on biogeochemical and CO2 measurements during spring, summer or autumn, but there are few data for the winter or winter–spring transition, particularly in the High Arctic. Here, we present carbon and nutrient data within and under sea ice measured during the Catlin Arctic Survey, over 40 days in March and April 2010, off Ellef Ringnes Island (78° 43.11′ N, 104° 47.44′ W) in the Canadian High Arctic. Results show relatively low surface water (1–10 m) nitrate (<1.3 µM) and total inorganic carbon concentrations (mean±SD=2015±5.83 µmol kg−1), total alkalinity (mean±SD=2134±11.09 µmol kg−1) and under-ice pCO2sw (mean±SD=286±17 µatm). These surprisingly low wintertime carbon and nutrient conditions suggest that the outer Canadian Arctic Archipelago region is nitrate-limited on account of sluggish mixing among the multi-year ice regions of the High Arctic, which could temper the potential of widespread under-ice and open-water phytoplankton blooms later in the season

Big data opportunities and challenges for assessing multiple stressors across scales in aquatic ecosystems

Aquatic ecosystems are under threat from multiple stressors, which vary in distribution and intensity across temporal and spatial scales. Monitoring and assessment of these ecosystems have historically focussed on collection of physical and chemical information and increasingly include associated observations on biological condition. However, ecosystem assessment is often lacking because the scale and quality of biological observations frequently fail to match those available from physical and chemical measurements. The advent of high-performance computing, coupled with new earth observation platforms, has accelerated the adoption of molecular and remote sensing tools in ecosystem assessment. To assess how emerging science and tools can be applied to study multiple stressors on a large (ecosystem) scale and to facilitate greater integration of approaches among different scientific disciplines, a workshop was held on 10-12 September 2014 at the Sydney Institute of Marine Sciences, Australia. Here we introduce a conceptual framework for assessing multiple stressors across ecosystems using emerging sources of big data and critique a range of available big-data types that could support models for multiple stressors. We define big data as any set or series of data, which is either so large or complex, it becomes difficult to analyse using traditional data analysis methods

Ice interaction with Adams Island, Winter 1984-85

A small island can be taken as being representative of a man- made offshore structure. A comprehensive study of ice interaction with such an island and response of the ice sheet to environmental driving forces was carried out over the winter 1984/85. Measurements included meteorological and oceanographic factors as well as ice-cover movements and in-situ stresses. Tidal variations, both semi-diurnal and fortnightly, appear to be responsible for variable horizontal ice-cover movement rates and hence cyclical variations in measured ice stresses. Maximum total load generated on the island was approximately 60 MN, equivalent to an average stress of 300 kPa over the top 1 m of the ice thickness and 200 m width. Local pressures over an area of 0.5 m2 reached a maximum of 500 kPa.Un \ueelot peut \ueatre consid\ue9r\ue9 comme \ue9tant repr\ue9sentatif d'un ouvrage construit en mer. Une vaste \ue9tude concernant l'interaction des glaces avec un \ueelot et la r\ue9ponse du manteau glaciel aux \ue9l\ue9ments naturels a \ue9t\ue9 men\ue9e au cours de l'hiver 1984-1985. Les mesures effectu\ue9es ont port\ue9 sur les facteurs m\ue9t\ue9orologiques et oc\ue9anographiques, ainsi que sur les mouvements du manteau de glace et les contraintes in situ. Les variations des mar\ue9es, tant semi-diurnes que semi-mensuelles, semblent \ueatre responsables de la vitesse variable de d\ue9placement horizontal du manteau de glace et, par cons\ue9quent, des fluctuations cycliques des contraintes mesur\ue9es dans la glace. Le courant, le vent et la temp\ue9rature de l'air ont \ue9galement un effet sur les mouvements et les contraintes. La charge totale maximale exerc\ue9e sur l'\uee lot \ue9tait d'environ 60 MN, soit l'\ue9quivalent d'une contrainte moyenne de 300 kPa sur le premier m\ue8tre d'\ue9paisseur de glace, sur une largeur de 200 m. Les pressions locales sur une surface de 0,5 m2 ont atteint un maximum de 500 kPa.Peer reviewed: YesNRC publication: Ye

Ice pressures and behaviour at Adams Island, winter 1983/1984

As a continuation of an ongoing project, measurements of environmental conditions and ice cover responses were made around Adams Island over the winter of 1983/1984. These included current, tide, speed and direction of wind, air temperature, and thickness, temperature, and salinity of the ice. Wind profiles were measured over the ice surface; from these, drag coefficients of 0.001-0.005 were calculated. Horizontal movement rates of the ice cover varied from 20 to 300 mm/day. No direct correlation was found between ice cover movement and the wind and current measurements. In situ ice pressures measured around the island averaged 250 kPa.Dans le cadre d'un projet d\ue9j\ue0 en cours, les conditions environnementales et le comportement du manteau glacial qutour de l'\ueele Adams ont \ue9t\ue9 mesur\ue9s au cours de l'hiver 1983-1984. Les \ue9l\ue9ments suivants ont fait l'objet de mesures : courants, mar\ue9es, vitesse et direction des vents, temp\ue9rature de l'air et \ue9paisseur, temp\ue9rature et salinit\ue9 de la glace. Des profils de vent ont \ue9t\ue9 mesur\ue9s \ue0 la surface de la glace; les coefficients de tra\ueen\ue9e calcul\ue9s \ue0 partir de ces donn\ue9es variaient entre 0.001 et 0.005. Les vitesses de d\ue9placement horizontal du manteau glacial variaient entre 20 et 300 mm/jour. Aucune corr\ue9lation directe n'a pu \ueatre \ue9tablie entre le d\ue9placement du manteau glacial et les mesures des vents et des courants. Les pressions glacialles mesur\ue9es autour de l'\ueele se situaient en moyenne \ue0 250 kPa.Peer reviewed: YesNRC publication: Ye