Oceanography

Eddying vs Laminar Ocean Circulation Models and Their Applications

Eddy Kinetic Energy Definition

Bernard Barnier, Thierry Penduff and Clothilde Langlais Abstract Mesoscale eddies are ubiquitous and very energetic features of the ocean circulation. They are represented in the high resolution models used for ocean forecasting, but not yet in today's laminar, coarse-resolution ocean components of models of the climate system. However, advances in high performance computing are likely to change this in a near future, as the next decade should see the use of eddying models to become more and...

Adjoint Data Assimilation Methods

Abstract The use of adjoint methods in data assimilation is reviewed, and illustrative examples are presented. Adjoint operators are central to many operational data assimilation systems used for numerical weather prediction, and are gaining popularity in oceanography also. In this chapter we shall review the use of adjoint methods for data assimilation. We begin in Sect. 14.2 with an exploration of the concept of the adjoint of a linear operator, and the important properties that make it an...

Principle Of Hf Radar

Real-time surface current information is a valuable supplement to understanding coastal air-sea interaction and dynamical processes at the coastal scales. Coastal surface current information may be correlated to winds and tidal currents among other physical phenomena. High-frequency (HF) radars have been used for measuring surface current fields and ocean-wave spectra. The physics behind HF radar is based on backscattering from a moving rough sea surface. The Radar transmits electromagnetic...

Predictability of Ocean Energy

A key factor in the uptake of ocean energy will be predictability of produced energy (or water), as this will affect grid connections and the market price for electricity sold into local markets. Ocean currents, osmotic power, OTEC and submarine geothermal energy could potentially produce continuous, i.e., baseload, electricity, whilst tidal currents are forecastable for periods of days (with some modification due to weather). Even wave energy can be predicted 1-2 days in advance. All forms of...

Forecast Skill

As mentioned in Sect. 20.2, ENSO is the most predictable large-scale phenomenon on seasonal to interannual timescales, and is the major source of predictability. Successful predictions with a coupled seasonal forecast model are, therefore, often related to a model's ability to reproduce the slow coupled dynamics of ENSO and accurately forecast its amplitude, spatial pattern and detailed temporal evolution Wang et al. 2008a . The skill of forecasting ENSO varies depending on the season, as well...

Integrating Coastal Models and Observations for Studies of Ocean Dynamics Observing Systems and Forecasting

Jeux Des Familles Imprimer

Zhang, Bronwyn E. Cahill and Robert C. Chant Abstract In coastal oceanography, simulation models are used to a variety of ends. Idealized studies may address particular dynamical processes or features of coastline and bathymetry reproducing the circulation in a geographical region can compliment studies of ecosystems and geomorphology and models may be employed to simulate observing systems and to forecast oceanic conditions for practical operational needs....

Isopycnic and Hybrid Ocean Modeling in the Context of GODAE

Abstract An ocean forecasting system has three essential components (observations, data assimilation, numerical model). Observational data, via data assimilation, form the basis of an accurate model forecast the quality of the ocean forecast will depend primarily on the ability of the ocean numerical model to faithfully represent the ocean physics and dynamics. Even the use of an infinite amount of data to constrain the initial conditions will not necessarily improve the forecast against...

Dispersion Relation

Shallow Water Oceanography

Substitution of the solutions for < p(x, z, t) and n(x, t) into the Bernoulli equation (Eq. 8.11) will give the following relationship between wave frequency and wavenumber This is the dispersion relation (so-called for reasons which will become apparent later). A number of useful properties of the motion can now be derived. We will firstly examine the differences between waves in deep water and waves in shallow water. Waves in deep water are defined to be those for which the depth of the...

Marine Energy Resources Technologies Research and Policies

Abstract Marine energy technologies have enjoyed a resurgence of development since the late 1990s and there are now widespread international activities to develop marine energy technologies and project deployments, principally in mid-latitude countries, where wave and tidal stream resources are more energetic. Substantial new deployments of tidal barrages, essentially comprising hydroelectric technologies driven by seawater, are under evaluation or construction in a number of countries....

Introduction

Marine energy technologies have enjoyed a resurgence of development since the late 1990s and there are now widespread international activities to develop marine energy technologies and project deployments, principally in mid-latitude countries, where wave and tidal stream resources are more energetic. Substantial new deployments of tidal barrages, essentially comprising hydroelectric technologies driven by seawater, are under evaluation or construction in a number of countries. Technologies for...

Forms of Ocean Energy

For the purposes of this paper, ocean energy resources are defined as those energy resources, which use seawater as either the motive power or for its chemical or heat potential. There are at least six principal forms of ocean energy, which could be harnessed to produce electricity or other products. These forms are a. Ocean Thermal Energy Conversion (OTEC) Some authors consider offshore wind energy as a form of ocean energy but it is derived from the movement of winds, rather than the kinetic...

Ocean Energy Technologies

The range of ocean energy technologies is huge and varied for a number of reasons 1. There are a number of different forms of ocean energy 2. There are many different ways to extract energy from seawater 3. Ocean energy technologies are at an early stage of development and a wide range of experimentation is continuing. 4. No dominant technologies have yet emerged Because there is a wide range of options for energy extraction and no dominant technologies, it is unlikely that ocean energy...

Trends and Growth in Ocean Energy

The year 2008 was an important one for ocean energy. The world's first 'pre-commercial tidal demonstrator', the Marine Current Turbines' SeaGen tidal generator, began to feed electricity into the Northern Ireland Grid (Fig. 26.11a). Shortly afterwards, the world's first wave farm array (of three Pelamis devices) became operational at Agu adoura in northern Portugal (Fig. 26.11b). Fig. 26.11 Recent marine energy deployments. a MCT's SeaGen pre-commercial tidal demonstrator (Source and b Pelamis...

Scientific Objectives of Godae Ocean View

The GODAE OceanView Science Team (GOVST) was established in 2008, with the mission to define, monitor, and promote actions aimed at coordinating and integrating research associated with multi-scale and multidisciplinary ocean analysis and forecasting systems, thus enhancing the value of GODAE OceanView outputs for research and applications. Over the next decade, the science team will provide international coordination and leadership in The consolidation and improvement of global and regional...

References

Bentamy A, Ayina H, Queffeulou P, Croize-Fillon D, Kerbaol V (2007) Improved near real time surface wind resolution over the Mediterranean sea. Ocean Sci 3(2) 259-271 Bowen M, Emery WJ, Wilkin J, Tildesley P, Barton I, Knewtson R (2002) Extracting multi-year surface currents from sequential thermal imagery using the maximum cross correlation technique. J Atmos Ocean Technol 19 1665-1676 Chelton DB (2005) The impact of SST specification on ECMWF surface wind stress fields in the eastern tropical...

Movemricomwnp

COM-WNP (Multivariate Ocean Variational Estimation system Meteorological Research Institute Community Ocean Model western North Pacific version) uses MRI.COM as ocean model. The layer thickness near the surface follows surface topography in this z-coordinate model (Hasumi 2006). For the nonlinear momentum advection, the generalized entropy-preserving scheme (Ara-kawa 1972) is used, which is based on the concept of diagonally upward downward mass momentum fluxes along the sloping...

Voluntary Observing Ships

The Voluntary Observing Ships (VOS) scheme is an international programme comprising member countries of the WMO IOC that recruit ships to take, record and transmit marine meteorological observations whilst at sea. The VOS Scheme is a core observing programme of the Ship Observations Team (SOT) in the Observations Programme Area of JCOMM. There are three types of ships in the VOS Scheme such as selected ships, supplementary ships and auxiliary ships. A selected ship is equipped with sufficient...

Ocean Observing Systems

A wide variety of observation data types are used in GODAE assimilation systems. The data include both in situ and remotely sensed measurements from space. As will be discussed, each observing system has its own unique data issues and Fig. 4.1 Chart showing flow of ocean observations through the different stages of ocean data quality control in the U.S. Navy global HYCOM system. Stage 1 sensibility error checks are performed on the raw data stage 2 external data checks are performed in the...

Data Processing Issues

Satellite data processing includes different steps level 0 and level 1 (from telemetry to calibrated sensor measurements), level 2 (from sensor measurements to geophysical variables), level 3 (space time composites of level 2 data) and level 4 (merging of different sensors, data assimilation). Processing from level 0 to level 2 is generally carried out as part of the satellite ground segments. Assembly of level 2 data from different sensors, intercalibration of level 2 products, and higher...

Key Developments in SST Data Processing

During the past ten years, a concerted effort to understand satellite and in situ SST observations has taken place leading to a revolution in the way we approach the provision of SST data to the user community. GODAE, recognizing the importance of high resolution SST data sets for ocean forecasting, initiated the GODAE High Resolution SST Pilot Project (GHRSST-PP) to capitalize on these developments and develop a set of dedicated products and services. There have been key developments in data...

Ocean Data Quality Control

Abstract Automated ocean data quality procedures are presented. The procedures are logically grouped into four stages of processing, which when taken together form a complete sensor-to-prediction quality control system. The main features of the different ocean observing systems assimilated by GODAE are presented along with sources and types of errors that can occur in the data. Specific quality control procedures are described that test for these errors as well as more general procedures that...

Background Field Check

Background fields used to quality control ocean data include climatology, short-term forecasts, and global or regional analyses. In all cases, appropriate background error variances must be used. Background and background error fields valid at the observation sampling time are interpolated to the observation location. An innovation is formed (observation minus background) and normalized by the error estimate of the background field. Assuming errors are normally distributed, the probability the...

Satellite Sea Surface Temperature

Infrared and microwave satellite SST retrievals measure very different properties of the sea surface, requiring unique quality control procedures. In the sections to follow, residual cloud and aerosol contamination quality control tests are applied to infrared SST retrievals. Diurnal warming detection is performed for daytime retrievals from both infrared and microwave satellites. 4.4.4.1 Residual Cloud Contamination Infrared SST measurements are derived from radiometric observations at...

Temperature and Salinity Profiles

Profile observations are first checked for duplicate depths and strictly increasing depths. Reported levels that fail these tests are flagged and not used in the following profile quality control procedures. 4.4.6.1 Instrumentation Error Checks Special instrument specific error tests are applied to profile observations to identify errors that have unique profile signatures. These errors include temperature inversions at the bottom of the profile, spikes in the temperature profile, and positive...

Quality Control Decision Making Algorithms

The quality control outcomes of the various external data checks described previously are combined in a decision-making algorithm. The outcome of the decision-making algorithm is the overall indication of observation quality, which is used to select data for the assimilation. The decision-making algorithm is applied to each observed reporting level and, in the case of profile (and glider) observations, to the entire profile in the shape comparison test. Thus, for profile observations there are...

Observing System Design and Assessment

Bohemian Arrow Tattoo Designs

Abstract The use of models and data assimilation tools to aid the design and assessment of ocean observing systems is increasing. The most commonly used technique for evaluating the relative importance of existing observations is Observing System Experiments (OSEs), and Observing System Simulation Experiments (OSSEs). OSEs are useful for looking back, to evaluate the relative importance of existing of past observational components, while OSSEs are useful for looking forward, to evaluate the...

Pf11 ht rh

Is customarily written in terms of the Kalman gain and forecast covariance by using the Sherman-Morrison-Woodbury formula (Golub and Van Loan 1989), P+ Pf+i - Pf+iHf (R + H-Pf+iHf )-1HPf+i (13.20) (I - P +iH(Ri + HiPf+iHf )-1H)Pf+i (13.21) 1. Equations (13.19) and (13.22) are equivalent, but note that (13.22) only requires the inversion of an M x M matrix (in the definition of K ), while Eq. (13.19) appears to require the inversion of an N x N matrix. This reduction of apparent rank is a...

Overview Global Operational Oceanography Systems

Operational Oceanography

Abstract Several systems to compute routinely ocean forecasts have been developed within the Global Ocean Data Assimilation Experiment (GODAE). They are used to deliver operational services. The cornerstones of these systems are (1) input high quality observations obtained from space and in situ, available shortly after the measurement is done, (2) state-of-the-art realistic numerical model configurations, and (3) efficient assimilation system that combine the observations and the model...

System Design for Operational Ocean Forecasting

Abstract The scientific and technical advances in ocean modelling, ocean data assimilation and the ocean observing systems over the past decade have made the grand challenge of ocean forecasting an achievable goal with the implementation of the first generation systems (Dombrowsky et al. 2009). Implementation of these components into a truly operational forecasting system introduces a number of unique constraints that can lead to reduced performance. These practical constraints, such us the...

Satellite SST

Fig. 18.6 The profiles received in real-time on 13th September 2009 that represent the best profile available from previous retrievals and the source of the profile Fig. 18.6 The profiles received in real-time on 13th September 2009 that represent the best profile available from previous retrievals and the source of the profile are several known limitations to the use of observed SST for ocean forecasting with diurnal warming and skin effects. Specific algorithms are required to perform quality...

Interp k e [1 K

The cell average values are then recovered as, The exact integrals of the discrete integral variable are advantageous when Ax is chosen to be an integer multiple of AX i.e., Ax nAX such that a subset of k are equivalent to This formulation has been expressed for a uniform grid in Cartesian coordinates but this method is readily extended to non-uniform grids and other orthogonal curvilinear coordinate systems. It is also noteworthy that a centre point value is a second-order accurate estimate of...

Examples Of Tropical And Equatorial Tide

Oceanography 1940

Periodic movements which are directly related in amplitude and phase to some periodic geophysical force are defined a tides and astronomic tides are the most widely recognised phenomena affecting water levels (Pugh 1987). These tides are the harmonic fluctuations of water level developed through the gravitational attraction from astronomic bodies (mainly the sun and moon). In majority of the world's coastlines there are two tidal cycles per day (i.e. two high and low waters per day and these...

The Global Ocean Observing System

Global Coastal Bays

Over the last 10 years, a global ocean observing system (in situ and remote sensing) has been progressively implemented. The system, primarily designed to serve climate research, is used as a backbone for most operational oceanography applications. Although significant progress has been made (e.g. Argo and Jason are outstanding successes), sustaining the global ocean observing system remains a challenging task (Freeland et al. 2010 Wilson et al. 2010). There is also a pressing need to develop...

The Godae Intercomparison Project

Eddy Current Oceanography

Recently the GODAE Intercomparison Project has allowed to intercompare and perform accuracy and consistency assessment. The objectives of the project were to (a) demonstrate GODAE operational systems in operations (b) share expertise and design validation tools and metrics endorsed by all GODAE operational centers (c) evaluate the overall scientific quality of the different GODAE operational systems (results are summarized in Hernandez et al. 2009). This project involved the majority of...

Amphibious Warfare

Surf Zone Oceanography

Amphibious operations can be very sensitive to weather and oceanographic conditions. The offloading of troops and equipment from specialist amphibious shipping to a beachhead involves transfers from ships to landing craft, and from landing craft to the beach itself. Most navies possess a range of relatively small watercraft for use during amphibious operations. Such activities are sensitive to sea state, swell and surf conditions, tidal streams, longshore currents and rips, which must all be...

Evaluation and Intercomparison of Ocean Reanalysis

Factor Changes Matter

With the availability of satellite altimetry in near real-time since the launch of ERS-1 (1991) and TOPEX Poseidon (1992), assimilation techniques have been developed in order to provide more realistic descriptions of the ocean dynamics with ocean models. A first approach is to carry out reanalysis experiments, where models and assimilation are tuned to provide in the past the best description of the ocean circulation. Usually, the set of selected observations for assimilation is processed to...

Relocatable Ocean Atmosphere Model ROAM

Roam The Ocean

The Relocatable Ocean Atmosphere Model (ROAM) is used by the RAN to generate high resolution oceanic and atmospheric forecasts over limited domains of interest to the Australian Defence Force (ADF). ROAM is designed to be set up by non-expert users, with minimal input, anywhere in the Australian region (Herzfeld 2009), and is used routinely by RAN forecasters. The ROAM ocean model is initialised and forced by data from OceanMAPS, and is typically implemented at resolutions of 1-2 km. Figure...

Air Sea Fluxes of Heat Freshwater and Momentum

Air Sea Turbulent Fluxes Algorithm

Abstract An overview of the air-sea fluxes of heat, freshwater and momentum is presented with the emphasis being on methods used to determine these fluxes and the role they play within the wider climate system. The equations used to determine the various heat flux components and the wind stress (which is equivalent to the momentum flux) are described in detail, together with the main spatial characteristics of the resulting global fields. This is followed by an overview of currently available...

Ty pCDUyU2 Uy12

Where ux and uy are the zonal and meridional components of the wind speed respectively, and CD is the drag coefficient which depends upon the height of the wind measurement and the atmospheric stability as well as wave characteristics (e.g. Smith 1988 Taylor and Yelland 2001). Climatological analyses of the wind stress using these formulae with ship meteorological reports have been carried out in a number of studies (e.g. Hellerman and Rosenstein 1983 Harrison 1989 Josey et al. 2002). More...

Development of Operational Ocean Forecasting System Evaluation

The second use of data assimilation with ocean modelling has been dedicated to short terms ocean prediction. Operational oceanographic centres development is also related to the availability of satellite data. In the late 1990s, several groups had already proposed multivariate assimilation scheme enhancing ocean models capabilities, either based on quasi-geostrophic or primitive equation formulations (see Dombrowsky et al. 2009 for a quick historical introduction). In the framework of GODAE,...

The BLUElink Global Regional Model OceanMAPS

Oceanography Chart

The BLUElink Ocean Modelling, Analysis and Prediction System (OceanMAPS) is implemented at the Bureau of Meteorology (BoM) in Melbourne (Brassington 2010). It produces an analysis and 6-day forecast of ocean temperature, salinity, currents, sea surface height and mixed layer depth twice per week. Model output graphics are available from the BoM public website, and the model data itself is available to the RAN, and more generally for research purposes, from the BoM's 'Thematic Realtime...

An Overview of Recent Developments for Computationally Efficient Applications in Operational Oceanography

Abstract Ensemble-based methods have become very popular for data assimilation in numerical models of oceanic or atmospheric flows. Unlike the deterministic Extended Kalman Filter which explicitly describes the evolution of the best estimate of the system state and the associated error covariance, ensemble filters rely on the stochastic integration of an ensemble of model trajectories that are intermittently updated according to data, using the forecast error covariance represented by the...

Dynamical Evaluation of Ocean Models Using the Gulf Stream as an Example

Gulf Stream Eddy Trend

Joseph Metzger, James G. Richman, Eric P. Chassignet, Yann Drillet, Matthew W. Hecht, Olivier Le Galloudec, Jay F. Shriver, Xiaobiao Xu and Luis Zamudio Abstract The Gulf Stream is the focus of an effort aimed at dynamical understanding and evaluation of current systems simulated by eddy-resolving Ocean General Circulation Models (OGCMs), including examples with and without data assimilation and results from four OGCMs (HYCOM, MICOM, NEMO, and POP), the first two...

Ocean Modelling

The science about turbulent closure schemes is now fairly mature, but there may still be surprises associated with subtle aspects of vertical mixing in the deep ocean that may have important consequences on long time scales. Vertical mixing is also critically important for biogeochemical cycles, because it controls the return of nutrients to the surface euphotic zone, and therefore the magnitude of primary production. Another area where there still is room for improvement concerns the exchanges...

Tides and Internal Waves on the Continental Shelf

Internal Water Continental Shelf

Abstract We review recent laboratory experiments, field observations and numerical modeling of internal waves produced by tidal motions, with specific focus on the Australian North West Shelf. Distinct regimes are observed depending upon both the characteristics of the ambient density stratification, the topography, and the intensity of the tidal forcing. The character of the near boundary flow in the region where waves are generated is very important in determining the internal wave response....

First Intercomparison Experiments

Annual Meridional Heat Transport

The international Atmospheric Model Intercomparison Project (AMIP), in the framework of the World Climate Research Programme (WCRP) has provided a guidance for the oceanic modelling community. The aim of AMIP was to offer a comprehensive evaluation of the performance of atmospheric GCMs7 on climate and higher-frequency time-scales, and the documentation of their systematic errors. In a common modelling framework, that is, simulating the monthly variability of the atmospheric parameters for the...

Case Study 2Montara Well Head Blowout

During the morning of 21st of August 2009, well control at the Montara well head was lost. The Montara well head is located approximately 680 km west of Darwin off the Kimberly coast in Western Australia. An estimate of 400 barrels per day of crude oil was being discharged into the sea. The leak continued for 74 days discharging a total of 30,000 barrels until the well was successfully killed on the 3rd November 2009 (PTTEP Australasia). Asia-Pacific ASA provided modelling support throughout...

Classification of Ocean Energy Conversion Technologies

Location Fuel Cell Power Plants

There are a number of classification schemes for ocean energy conversion technologies. A primary classification can be made based upon the basic energy resource being harnessed 1. Potential and kinetic energy in waves and currents 2. Chemical potential of seawater (salinity gradients) 3. Heat potential of seawater (ocean heat and geothermal heat) 4. Biological potential of seawater 26.4.1.1 Wave, Tidal and Ocean Current Technologies These technologies effectively utilize the potential energy...

Coastal Tide Gauge Observations Dynamic Processes Present in the Fremantle Record

Abstract Coastal sea level variability occurs over timescales ranging from hours to centuries. Globally, the astronomical forces of the Sun and the Moon are the dominant forcing which results in the tidal variability with periods of 12 and 24 h. In many regions, the effects of the tides dominate the water level variability -however, in regions where the tidal effects are small other processes also become important in determining the local water level. In this paper, sea level data from...

Introduction to Ocean Data Assimilation

Conventional ocean modeling consists of .solving the model equations as accurately as possible, and then comparing the results with observations. While encouraging levels of quantitative agreement have been obtained, as a rule there is significant quantitative disagreement owing to many sources of error model formulation, model inputs, computation and the data themselves. Computational errors aside, the errors made both in formulating the model and in specifying its inputs usually exceed the...

Marine Biogeochemical Modelling and Data Assimilation

Assimilation Marine Definition

Abstract The inclusion of biogeochemistry into the Global Ocean Data Assimilation Experiment systems represents an exciting opportunity that involves significant challenges. To help articulate these challenges we review marine biogeochemical modeling and the existing applications of biogeochemical data assimilation. The challenges of biogeochemical data assimilation stem from the large model errors associated with biogeochemical models, the computational demands of the global data assimilation...

Basin Scale Observing System IndOOS

Of the three major oceans Pacific, Atlantic, and Indian the Indian Ocean has is the only one that is not open to the northern subtropical regions. This is a consequence of the presence of the Asian landmass restricting the Indian Ocean to south of about 25 N and hence it cannot transport heat gained in the tropics to the higher northern latitudes, as the Pacific and Atlantic oceans do, mainly via their western boundary currents. Furthermore, the Indian Ocean is the only ocean with a...

Radiation Laws and Emissivity 2331 Radiation from a Blackbody

Planck's law describes the rate of energy emitted by a blackbody as a function of frequency or wavelength. A blackbody absorbs all the radiation it receives and emits radiation at a maximum rate for its given temperature. Planck's law gives the intensity of radiation Lx emitted by unit surface area into a fixed direction (solid angle) from the blackbody as a function of wavelength (or frequency). The Planck Law can be expressed through the following equation where T is temperature, c the speed...

Argo Profiling Floats

The Argo oceanographic radiosonde is a revolutionary concept that enhances the real time capability for the measurement of temperature and salinity through the upper 2,000 m in the ice free global Ocean. The exclusion of the high latitudes was due to the inability of early floats to sample under sea-ice. However, technological advances in float design in recent years now give us this capability. Advancements have come through re-design of hardware (i.e. armoured ice floats with ice-hardened...

Brief History of Oceanography

The focus of this article and this book is on the two branches of oceanography that Physical oceanography, or marine physics, that studies the ocean's physical attributes including temperature-salinity structure, mixing, waves, internal waves, surface tides, internal tides, and currents, acoustical and optical oceanography and, to some extent, biogeochemical oceanography which involves the scientific study of the chemical, physical, geological, and biological processes and reactions that govern...

Data Assimilation Statistics

In the data assimilation process, the observation operator h is used to interpolate the model forecast field xf to the location in time and space of the observations, y-This enables calculation of the innovations, d y - h(xf) . Once the data assimilation has been performed it is also possible to calculate the equivalent using the analysis field to produce the residuals, r y - h(xa) . The reduction in the errors between the analysis and the forecast can be used as an a posteriori check that the...

Impacts of the Ocean on Operations 2421 Anti Submarine Warfare ASW

Sound Speed Profile Australia

The need for specialist oceanographic expertise first came to be recognised by the RAN in the mid 1950s, when the Fairey Gannet Anti-Submarine Warfare (ASW) aircraft was first operated from the aircraft carrier HMAS MELBOURNE. Meteorological officers onboard MELBOURNE provided tactical oceanographic advice to the Gannet squadrons, using bathythermographic observations of the ocean as the basis for sonar performance predictions. This advice was used by the Gannet crews to determine the optimum...

General Environmental Effects

The key effect will be occupation of sea space, particularly for 'arrays' or 'farms' of devices, a problem potentially exacerbated by regulatory requirements for exclusion zones to prevent other activities, e.g., fishing, particularly trawling, in the same area. Ocean energy projects will compete for access to sea space with pre-existing or pre-assigned uses, such as fishing quota zones, marine reserves and areas reserved for military use and shipping lanes. Hard structures, such as converter...

Summary Diagrams

In order to characterise the differences between the model and observations it is important to take into account the correspondence in both the patterns and the variances of the two fields. We define the centred pattern RMSD as Taylor (2001) noticed that a simple relationship exists between the correlation coefficient, the centred pattern RMS difference, and the variances of the fields in question. The relationship is given by which takes the same form as the law of cosines (c2 a2 + b2 - 2ab...

Acoustic Tomography

The ocean is largely transparent to sound, but opaque to electromagnetic radiation. Underwater sound is therefore a powerful tool for remote sensing of the ocean interior. This technique is used in Ocean Acoustic Tomography. It is used to measure temperatures and currents over large regions of the ocean (Munk et al. 1995). On ocean basin scales, this technique is also known as acoustic thermometry. The technique relies on precisely measuring the time it takes sound signals to travel between two...

Ships of Opportunity

The primary objective of the Ship-of-Opportunity Programme (SOOP) is to fulfill the XBT upper ocean data requirements established by the international scientific and operational communities, which can be met at present by measurements from ships of opportunity. The annual assessment of transect sampling is undertaken by the Joint WMO-IOC Technical Commission for Oceanography and Marine Meteorology (JCOMMOPS) on behalf of the Ship Of Opportunity Programme Implementation Panel (SOOPIP). Data...

Summary and Conclusions

Over the past 40 years, numerical modelling has developed rapidly in scope (from hydrodynamics to ecology) and resolution (from one-dimensional, 102 elements to three-dimensional, 108 elements) exploiting the contemporaneous development of computing power. Although we have made significant progress with the implementation of the global ocean observing system, concurrent development in observational capabilities has not been achieved yet in areas demanding high spatial resolution such as coastal...

High Level Data Processing Issues and Products

The SSALTO DUACS system is the main multi-mission altimeter data center used today for operational oceanography. It aims to provide directly usable, high quality near real time and delayed mode (for reanalyses and research users) altimeter products to the main operational oceanography and climate centers in Europe and worldwide. Main processing steps are product homogenization, data editing, orbit error correction, reduction of long wavelength errors, production of along track and maps of sea...

Drifting Buoys

For several years, oceanographers and meteorologists have deployed satellite-tracked drifting buoys in support of their research and operational programmes. These two bodies of users have, however, sought different capabilities from their drifters the oceanographers have mainly looked for designs which accurately follow water parcels at a given depth, whereas the meteorologists have equipped their drifters with air-pressure sensors to collect real-time observations for weather forecasting....

Location Speed Test

A location (speed) test is used to determine if the reported position of an observation is consistent with prior positions from the same platform. The test is necessarily restricted to data types that report unique call signs, such as Argo floats, surface ships, aircraft, and fixed and drifting buoys. Observations failing the location speed test are typically scheduled for manual intervention. No automated method exists at the present time to correct erroneous reported positions. The speed test...

Ship and Buoy Sea Surface Temperature

Volunteer observing ship (VOS) temperatures have very different error characteristics depending on the measurement method. Hull contact sensor measurements of temperature appear to be the most accurate followed by engine room intake and buckets. However, all ship-based measurement systems are prone to error since the on-board instruments are rarely calibrated. In general, ship-based SST measurements are noisy and observations from engine-room-intake instruments tend to be warm biased, while...

Surface Waves

Abstract In this chapter, we first present the governing equations for linear wave theory. This provides a simple but yet powerful description of the wind-driven waves on the ocean surface. A number of important concepts are derived, including the dispersion relation. From the dispersion relation we examine some differences between waves in deep water and waves in shallow water and in particular we demonstrate that deep water waves are dispersive, while shallow water waves are non-dispersive....

Wave Energy

Wave energy is present across the globe and can be harnessed as a combination of kinetic and potential energy of water particles. Waves are created by the action of winds passing over the surface of the ocean. Wave heights (and thus energy) are greatest in the sub-equatorial regions where the trade winds (such as the 'Roaring Forties') are strong and blow consistently in the same direction over long distances (Fig. 26.1). Fig. 26.1 Global distribution of annual mean wave power. (Cornett 2008)...

Overview of Satellite Oceanography Techniques 231 Passive Active Techniques and Choice of Frequencies

There are two main types of satellite techniques to observe the ocean1. Passive techniques measure the natural radiation emitted from the sea or from reflected solar radiation. Active or radar techniques send a signal and measure the signal received after its reflection at the sea surface. In both cases, the propagation of the signal through the atmosphere, the emission from the atmosphere itself must be taken into account to isolate the sea surface signal. The intensity and frequency...

Elements of Observing System 321 Tide Gauges

The measurement of changes in sea level to understand the mechanisms responsible for phenomena such as the tides and the catastrophic floods due to storms and tsunami was performed by the observers of the Ocean from ancient times. It is now realized that sea level changes are important on all timescales from seconds (due to wind waves) through to millions of years (due to the movement of continents). The devices employed to make sea level changes (relative to the level of the land where the...

Persistence

Point observations, such as temperature profiles from eXpendable Bathy Thermograph (XBT) systems, have been used by navies for many decades to infer the acoustic properties of the water column. These observations are relatively simple to make, and do not require assistance from ashore. This approach amounts to a persistence forecast, that is, an assumption that the water properties will not change during the period for which the assessment is required. It also assumes that there is no spatial...

An Australian Perspective

Abstract Oceanographic conditions can affect naval operations in a variety of ways, and for this reason navies around the world have traditionally used oceanographic observations, and climatologies derived from them, for operational decision making. Rapid advances in global ocean observing systems since the 1990s, and more recently in operational ocean forecasting systems, offer substantial opportunities for improved decision making. The recent focus of many defence forces on information...

Validation and Intercomparison Methodology

Mooring Lines Definition

The assessment methodology used ultimately for the GODAE intercomparison project is a direct heritage of the validation activity performed earlier in the framework of operational oceanography projects. It is based on two aspects (Crosnier and Le Provost 2007). First, the philosophy a set of basic principles to assess the quality of OFS products systems through a collaborative partnership Consistency verifying that the system outputs are consistent with the current knowledge of the ocean...

International Initiatives

There are a number of regional and international initiatives for promotion and development of ocean energy. Table 26.1 Government policy instruments for ocean energy Table 26.1 Government policy instruments for ocean energy Legislated Targets, A s pi rational Targets and Forecasts 3 of UK electricity from ocean energy by 2020 500 MW by 2020 550 MW by 2020 US DoE Hydrokinetic Program (capital grants for R & D and market acceleration) Marine Renewables Proving Fund (MRPF) and Marine Energy...

Case Study 1Pacific Adventurer

Tropicalcyclone Fantala Formulation

In the early hours of the morning on the 11th of March 2009 the Pacific Adventurer encountered severe weather conditions (as a result of nearby Tropical Cyclone Hamish) whilst on route from Newcastle to Indonesia. As a result of the severe weather conditions, 31 shipping containers (containing a total of approximately 600 tonnes of ammonium nitrate) were lost overboard. Several of the containers ruptured the ship's fuel tanks, which resulted in the loss of 270 tonnes of heavy fuel oil to the...

Forecast Methods Their Strengths and Weaknesses 2431 Climatology

Oceanography Somalia

Until the recent advent of operational oceanography, navies have had to rely on climatologies or point observations to make operational decisions (Jacobs et al. 2009). Climatologies can be useful for planning purposes, but they are of limited use where oceanic variability is high. In the extreme case of a bimodal system, climatology shows the mean of the two modes, which may be a physical situation that never arises in reality (e.g. south or north of a front, inside or outside an eddy). Figure...

Environmental Impacts of Ocean Energy Converters

The successful development of ocean energy will depend on public acceptance of ocean energy technologies. Apart from competition for space and allocation of resources, which will be subject to regulatory interventions, there will be a requirement on ocean energy device developers to demonstrate that their technologies have limited impacts on the surrounding environment. Regulatory interventions will be necessary to ensure that project developers follow good environmental practice and avoid,...

Tidal Energy

Tide Current Map

Tidal energy can be divided into two distinct forms Tidal rise and fall energy is potential energy derived by height changes in sea level, caused by the gravitational attraction of the moon, the sun, and to a lesser extent other astronomical bodies, on oceanic water bodies. The effects of these tides are complex and most major oceans and seas have internal tidal systems, called am-phidromic systems (Fig. 26.2). Each major ocean has its own internal circulation system, called 'gyres', which...

First Installation Site Garden Island WA

The first full scale CETO devices will be deployed in an area near Garden Island off the coast of Western Australia as in Fig. 27.3. This is ultimately the planned site for a 5 MW wave farm comprising multiple CETO units that is expected to be one of the first (if not the first) commercial scale wave farm in the southern hemisphere. Grid connected power is expected to be available by 2012. The site is located in the Sepia Depression, an area of 20-25 m water depth between Five Fathom Bank and...

Evaluating the Large Scale Mean and Variability

It is important to check that the average properties of the ocean forecasting systems are providing a good representation of the ocean climate. This is usually done by comparing multi-annual averages to climatologies generated from observational data-sets. One example of this is a comparison between a mean dynamic topography (MDT, such as that of Rio et al. 2005 or Maximenko and Niiler 2005), with the model's average sea surface height field. This provides a useful guide as to the ability of...

Mine Warfare

Mine Warfare operations include mine hunting (using specialist sonars and Remotely Operated Vehicles (ROVs)), mine sweeping, and mine clearance diving. These operations are generally conducted in littoral environments, which can be challenging due to the complexity of ocean conditions. Tidal streams are often strong, turbidity can affect visibility, and variations in the bottom type and thermohaline structure can make acoustic detection difficult. In order to achieve good detection and...

Impacts on Marine Biota

The effects of arrays of ocean energy converters on marine mammals, elasmo-branchs (i.e., sharks) and other marine fauna are likely to be principally habitat modification, collision risk, noise and electromagnetic fields. As noted above, placement of artificial structures on the seabed will modify local current patterns and cause scouring or sediment deposition. However, these effects are likely to be limited with respect to tidal or ocean current devices. In the case of tidal current devices,...

Pragmatic Approaches in a Commercial Context

Carnegie in its development of CETO wave sites worldwide generally favours the approach of using coarse gridded WWW3 data as a guide to determining general feasibility, then making detailed selections based on deployed tri-axis wave measurement accelerometers, rather than 'gridding in' coarser wave data to finer scales. This approach works in practice because at scales finer than the typical WWW3 grid, the decision about the most suitable site for a wave energy converter is no longer solely...

Specific Uses of Ocean Observations Analysis

The CETO Wave Energy Project has benefited from the vast store of oceanographic data, observations and analysis throughout the course of its development to date, and will continue to draw on the knowledge base as projects are developed worldwide. At this stage of project development, the utility of ocean observations and analysis has been restricted to site selection, validation and calibration studies. It is noted however that operational forecast products are expected to become increasingly...

Salinity Gradients

Seawater is approximately 200 times more saline than fresh river water, derived from rain, snowmelt or groundwater and is delivered to the coast by major rivers. Global salinity differences arise from submarine and surface current movements (Fig. 26.6). The relatively high level of salinity in seawater thus establishes a pressure potential with sweet river water, which can be used to generate electricity or derive fresh (drinking) water from the seawater. This 'osmotic' pressure differential...

Spill Forecast Bulletin for Montara Incident Issued Midday 29October2009for the Australian Maritime Safety Authority

Over flight and satellite observations collected from the 24th-28th October 2009 have been used to update oil, oil patches and wax positions within the AMSA OIL-MAP Oil Spill Trajectory Model (OSTM). The recent satellite observations indicated that the slick was patches of oil wax lying east and southeast of Montara extending to the south as patches (refer to Fig. 25.5). The winds have remained favourable over recent days which has seen the edge of the slick move parallel to the coast...

Case Study 3MSC Lugano Stranding

The MSC Lugano is a 240 m container ship which was en route from Adelaide in South Australia to Fremantle in Western Australia. On the 31st of March 2008 it was disabled by an engine room fire and as a result, was in jeopardy of grounding off Esperance, Western Australia. Three tugs from nearby Esperance were called in to provide assistance, whilst another larger and better equipped tug was en route from Fremantle. The tugs took Table 25.2 Metocean forecast products used during the Montara well...

BLUElink Ocean Model

The BLUElink project became operational in 2007 from the collaboration between the Australian Bureau of Meteorology (BoM), Royal Australian Navy (RAN) and the Commonwealth Scientific Industry Research Organisation (CSIRO 2010). Operationally, it is now under the management of the Australian Bureau of Meteorology. There are several components to the BLUElink system, including operational forecasts, reanalysis and data assimilation. The operational forecasts from BLUElink used in this study were...

User Oriented Validation

As mentioned earlier, most of the validation methodology proposed for ocean models and OFS is based on the oceanographer point of view. That is, evaluation of the large scale circulation, and smaller scale features in a general sense. Even if accuracy number and error bars can be produced by this approach, they might not fully satisfy some users. For instance, a merchant ship captain may not be satisfied with a daily averaged map of sea-ice concentration, instead, he might prefer a map of...

Case Studies for Particular Applications

As described previously, ocean forecasting systems serve a large number of users. Among the most significant of these are the Navies, who are interested in a number .08' Global HYCOM (82.4) Median SSH Anomaly Correlation wldocn number of forecasts 48 (01-Jun-2007 to 22-May-2008) .08' Global HYCOM (82.4) SSH Median RMS error wldocn number of forecasts 48 (01-Jun-2007 to 22-May-2008) .08' Global HYCOM (82.4) Median SSH Anomaly Correlation wldocn number of forecasts 48 (01-Jun-2007 to 22-May-2008)...

Forecast Versus Analysis

In order to assess the forecasts from ocean models, one can assume that the analysis produced by the data assimilation is providing a best estimate . The subsequent forecast can be compared against the analysis (at the correct time), and the differences between these fields can be used, over a large number of realisations, to assess the skill in the model forecast. Various statistics can be calculated based on these differences the most commonly used are RMSD, mean and anomaly correlations, as...

Seasonal and Decadal Prediction

Oscar Alves, Debra Hudson, Magdalena Balmaseda and Li Shi Abstract Dynamical seasonal prediction has grown rapidly over the last decade or so. At present, a number of operational centres issue routine seasonal forecasts produced with coupled ocean-atmosphere models. These require real-time knowledge of the state of the global ocean since the potential for climate predictability at seasonal time scales resides mostly in information provided by the ocean initial conditions, in particular the...

W m 2 x x2 y y2

Figure 13.4 shows the general scale of flow features which can be identified from this rather limited, and idealized, observational array. The spatial density of the measurements has been chosen to be compatible with the 12.5 km correlation scale of the sea-surface height. Figure 13.5 illustrates what happens when the observing array either over- or under-samples the variability of the unknown field. In the case where the unknown field has a correlation scale of L 3 km (Fig. 13.5, left panel),...

Xa Xb aXX Vyy Xb136

In spite of its simplicity, this example shows some of the key features of advanced linear data assimilation methods. First, note that the optimal estimate in Eq. (13.6) is a linear combination of the background xb and the residual y - xb. The term Sxa a2x(a2x + o2y)- y - xb) (13.8) is called the analysis increment. Note the limits ox 0 (perfect background) and y 0 (perfect data), which yield xa xb and xa y, respectively. Furthermore, the estimated variance of the optimum (13.7) is less than...

Altimeter Sea Surface Height

The along-track altimeter data undergo an extensive series of pre-processing steps to prepare the data for use in the assimilation. The measured sea surface height (SSH) is corrected for geophysical effects (wet and dry troposphere, ionosphere, inverted barometer, and winds), and the tidal signal is removed. The corrected SSH from each satellite altimeter mission are then intercalibrated with a global crossover adjustment using Topex Poseidon data as the reference. Next, the data are resa-mpled...

Repeat Hydrography and Carbon Inventory

Despite numerous technological advances over the last several decades, ship-based hydrography using research vessel remains the only method for obtaining high-quality, high spatial and vertical resolution measurements of a suite of physical, chemical, and biological parameters over the full water column (Hood et al. 2009). It is worth mentioning here that VOS and SOOP collect data while cruising, whereas research vessel stops at different locations and collect surface and subsurface data upto...

Concluding Remarks

The chapter provides only a very brief summary of ocean remote sensing measurement principles. More information can be found in Fu and Cazenave (2001), Robinson (2004) and Martin (2004) books. Satellite data play a fundamental role for operational oceanography. They are mandatory to constrain ocean models through data assimilation and they provide directly useable data products for applications. Over the past 10 years, new and improved data sets and products needed by the modeling and data...

Operational Oceanography Requirements

The needs and the broad classes of colour sensor are summarised in Tables 2.5 and 2.6 from Le Traon et al. (2006). They distinguish categories of use between the needs of the open ocean forecasting models, the finer scale shelf sea and local Table 2.5 User requirements for ocean colour data products Table 2.5 User requirements for ocean colour data products Minimum set of satellite-derived variables needed Table 2.6 Classes of ocean colour sensor Class Orbit Sensor type Revisit time Spatial...

Measurement Principles

The sunlight is not merely reflected from the sea surface. The colour of water surface results from sunlight that has entered the ocean, been selectively absorbed, scattered and reflected by phytoplankton and other suspended material in the upper layers, and then backscattered through the surface. The subsurface reflectance R(A) (ratio of subsurface upwelled or water-leaving radiance on incident irradiance) that is the ocean signal measured by a satellite is proportional to b(A) a(A)+b(A) or...

Ocean Colour Measurements and Operational Oceanography

Over the last decade, the applications of satellite-derived ocean colour data have made important contributions to biogeochemistry, physical oceanography, ecosystem assessment, fisheries oceanography and coastal management (IOCCG 2008). Ocean colour measurements provide a global monitoring of chlorophyll (phytoplankton biomass) and associated primary production. They can be used to calibrate and validate biogeochemical, carbon and ecosystem models. Progress towards assimilation of ocean colour...