[ Home ] [ Up ] [ Next. ]

1. Introduction

Progress in numerical modelling, the availability of satellite-borne sensors, and global ocean observation programmes, have led to the understanding of large fluctuations in the coupled ocean-atmosphere system. The possibility of seasonal forecasting of the coupled ocean-atmosphere system could have considerable economic benefits, but it cannot be done without appropriate ocean models and observations. In several countries, operational ocean–atmosphere models are being developed to enable nowcasting and forecasting.

Ocean observing systems are required in support of those operational objectives, as well as for ocean models assessment and validation; for understanding and modelling the ocean role in climate; monitoring ocean changes; and enabling long-term trends prediction.

GyroScope aims to develop a key component of such a system, that will provide, for the first time, basin-wide in situ ocean observations with a sampling appropriate to resolve seasonal and inter-annual variability. The detection of longer time scale climate signals will require that such observing systems be maintained permanently.

The overarching objective of the GyroScope project is to develop a European component of a global in situ observing system of ocean variability in the North Atlantic, based on autonomous, freely drifting profiling floats, which can measure vertical profiles of temperature and conductivity (from which salinity can be deduced) at regular intervals. The data are transmitted by satellite to a receiving station.

The first objective is to deploy a pilot array of about 80 autonomous profiling floats, as a contribution to the international ARGO programme. This array will transmit in real time data to Data Centre Ifremer, that will quality control, and distribute it on the Global Telecommunication System for use by National Weather Services, and operational agencies. The data will be used to estimate the time varying ocean circulation, temperature and salinity fields, and the balance of heat in the North Atlantic. Some of the estimations will be done in real time ; other will include complementary data sets (satellite altimetry) to obtain the most accurate estimates and assess the information content of the float data (resolution, accuracy). Recommendations will be made for future implementation of an in situ ocean observing system.

This project involves a combination of field work, data processing and evaluation, numerical modelling of ocean circulation, and studies of ocean circulation and ocean-atmosphere interactions on large scales.

The User Requirement Document identifies and characterizes the main user groups ; it specifies the sort of results they would find useful from the project. It is anticipated that the document will evolve as the project progresses. As interactions with users develop, it is in the sort of results and products that adjustments are most likely to be made in the course of the project.

An important class of users is the is the research and development community engaged in improving operational ocean models. The GyroScope project will provide the needed in situ data to those models. In the present document, we do not consider the users of the outputs of those ocean models, as they are further downstream from our outputs.

The most original and significant output of the GyroScope project is the distribution of large scale in situ ocean data, in real time, to a large number of users. Through the Coriolis Data Centre, the quality controlled data will be broadcast on the WMO Global Telecommunication System (GTS) with a maximum delay of 48h ; the data will also be available in near real-time via the internet. As such the data will be available for use worldwide by a large class of users : national weather services, operational agencies, and research scientists.

The data will serve as input to a hierarchy of operational ocean models, into which they will be assimilated. The models will in turn be used to generate products for the support of marine operations, fishery management, coastal forecasts, etc… Those derived products provide an added value to GyroScope, but do not belong to the project itself, so that they are not included in the present assessment.

Data synthesis will be produced in various forms, to make the observations more readily understandable to a larger audience : the general public, policy makers, and the media.

The final report will include recommendations for implementation of operational ocean observing systems, which will prove useful to agencies with responsibilities toward the ocean and the environment.

The instrumental aspects of the project –evaluation, recommendations for improvement– should provide valuable feedback to instrument manufacturers to develop their products and improve their market prospects.

The real-time data distributed automatically, systematically, and regularly on the GTS will be available to national weather services for their routine daily forecasts. At the present time, the forecast models only use sea surface temperature data (SST). Because of the operational requirement, timely delivery of the data is of the essence : this is ensured by automatic quality control and broadcast on GTS.

The weather services do not currently use subsurface information in making their daily forecasts ; but extended (seasonal) forecasts made using coupled ocean-atmosphere models are very dependent on such data. The GyroScope data will be available for such long range forecasts, for instance to the ECMWF, the Météo France, and the UK Met Office.

The user requirement, for daily forecasts is for very short delay (less than 24hrs) availability of SST data on the GTS ; for seasonal forecasts, the requirement is less stringent, of the order of a few days.

Operational ocean models require in situ data at regular intervals as input to the assimilation schemes. Models run by Météo France and the hydrographic and oceanographic service of the French navy (Mercator, Soprane) and the UK Met Office (Foam) will receive and incorporate the GyroScope data at each surfacing of the floats. Through the GTS, the data will be available to other operational agencies (in the USA, for instance : National Centre for Environmental Prediction, NCEP, and Fleet Numerical Oceanographic Center, FNOC). Note that the UK Met Office and the French Navy are participants in the GyroScope project.

The Service Hydrographique et Océanographique de la Marine (Shom) is a governmental agency, one of whose missions is to satisfy Defense requirements in marine environment knowledge. In short, the requirements are to enable the best possible description and forecast of the hydrological situation for spatial and temporal scales affecting Sonar performance detection.

To achieve this, Shom carries out research and development programs on operational monitoring of the ocean.

For such applications Shom, and beyond that the community involved in operational oceanography, has strong requirements for :

1. Real time validated in-situ profiles of temperature and salinity. Individual profiles are an essential input to the assimilation schemes to properly constraint numerical models. They also can randomly sample specific phenomenon such as meddies, which are not yet fully described in the models.

2. Quick-look analyzed products, such as maps of temperature and/or salinity at different levels. These products are expected to be a valuable extra source of information for the marine "forecaster" to compare with routine model outputs and to help improving the quality of navy end-user products.

3. Feedback on observation array design suitable for meso-scale forecasting models support. This could be assessed by sensitivity surveys.

 

The user requirement is for in situ data, quality controlled, with short delay (less than 48hrs), disseminated on the GTS or easily available via the internet from the Coriolis data centre, as well as quick look, synthetic products.

Scientists in agencies and international bodies (ICES) working stock assessment and population dynamics (tuna, billfish, swordfish, anchovy, etc…) need information on horizontal distribution of temperature at different depths, mixed layer and thermocline depth, as well as the time evolution of these parameters. Important population parameters, such as recruitment, natural mortality or growth pattern are influenced by oceanographic conditions. For instance, the Standing Committee on Research and Statistics of ICCAT (International Commission on the Conservation of Atlantic Tuna) has recently established a permanent subcommittee on the environment, which has strongly recommended to include oceanographic data in the assessment models as well as in the standardized catch rate procedure.

The data will be used on different time scales : in the long term, reconstructions of temperature and salinity fields will help understand biological time series ; near real time (monthly) reconstructions can be used as environmental indices by fishery agencies engaged in stock assessment; daily data in support of specific field operations. To be of use, the data must be presented in concise form, typically maps of temperature at different depths, or anomalies from climatology.

The user requirement the same as either the near real time data in the form of data synthesis (temperature maps, front location, for instance), or higher quality data (individual profiles or objectively mapped fields).

The unique data set collected in the course of the project will provide the basis for scientific analysis of ocean processes for years, not only by GyroScope participants, but also by the larger scientific community. For such studies, the GyroScope data set will be combined with other data. Here, the real time aspects are of less relevance, but the collection of data regularly in time is a major innovation. For the scientific community, it is essential that the data be carefully calibrated and validated. Detailed, accurate, quantitative estimates of ocean processes are required : fluxes, transports, water mass formation rates, temperature and salinity changes.

Ocean observations are so rare and valuable that what little data there is, is used for many years. Cases in point are the International Geophysical Year (1957-58), or the World Ocean Circulation Experiment (1990-98) data which form the basis of many climatologies. The GyroScope data, as a contribution to Argo, will provide a reference dataset on large scale oceanography, within which diverse process studies will be conducted.

The International GODAE Steering Team viewed the weakness of the in situ observing system as the principal area requiring urgent attention for conduct of a plausible experiment (mesoscale and seasonal forecasting) ; CLIVAR views Argo as one of the corner stones of a long term observing system for the ocean’s climate.

At the conclusion of the project, the complete and fully validated data set will be archived at the Data Centre and distributed to other international data centres (NODC, BODC). Data summaries on CD ROMs will be distributed widely. It is hoped that the final recommendations of the GyroScope project will lead to implementation of the Argo concept on a longer-term basis. The data collected will be the legacy to the climate research community, which needs long time series with wide coverage for climate change detection and attribution. The availability of the data to the scientific community increases its usefulness and its valorisation.

The research community will use the GyroScope data in combination with other data sets, to obtain optimal information on ocean state. Operational ocean models need in situ data to improve methods for assimilation of altimeter data. Thus GyroScope will contribute to the development of operational systems.

The requirement is for data of the highest quality, optimum estimates of ocean fields, statistical analysis of variability, accurate estimation of ocean balances, and rigorous scientific analysis.

The general public, including the media, show great interest in knowledge and understanding of our global environment. The appropriate products for that audience must be simple and illustrative (maps of sea surface temperature and changes, or the position of major currents, for instance). The real time data synthesis developed by the project will have great educational value. They will be available to the general public and the media through the project WEB site ; links will be established with other sites for maximum exposure of our results.

The requirement is for summaries of easily understood properties (such as maps of currents or temperature), with attractive presentation and clear explanations. It must be easy to access, as on the Internet.

The GyroScope project aims to develop an essential component of an ocean observing system, that will provide the data necessary to initialise and to validate ocean forecast models. The observing system will be designed with an operational objective in mind, that is to make recommendations for future implementation of a permanent array.

The United Nations Framework Convention on Climate Change (UNFCC) emphasized the need to enhanced and develop ocean observing systems (development of data archives ; systematic observation ; international and intergovernmental efforts to strengthen systematic observation and national scientific and technical research capacities and capabilities).

One outcome of the project will be a report, aimed at policy makers, defining a strategy for implementation of a longer-term operational ocean observing system.

The requirement is for concise reporting, recommendations and cost/benefits estimates.

One of the objectives of the project is to give a thorough assessment of the performance of the instruments used, and to compare the various types and sensors. This technical evaluation is required by the manufacturers to improve the instruments and to produce more competitive instruments.

The development in Europe of ocean observations with expendable instruments will open new market opportunities for manufacturers. The development of operational oceanography in Europe is bound to create new markets for European companies, which need the feedback from projects such as GyroScope.

The requirement is for comparative technical data on float performance.