Jason-2

Jason-2 reliably delivers detailed oceanographic data vital to our understanding of weather forecasting and climate change monitoring.

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The Jason-2 programme links two operational and two research agencies (EUMETSAT, NOAA, CNES and NASA) and also brings about a transition from a research phase towards operational applications.

One of the major objectives of the Jason-2 Ocean Surface Topography Mission is to support operational oceanography.

  • Nearly 71% of the Earth's surface is covered by oceans.
  • Two-thirds of the world's population live within 60 kilometres of the coast.
  • Half of the world's cities, with more than one million people, are situated around river mouths.

Oceans are a major source of food and employment, but can also pose a threat to lives and values, so operational forecasts of the ocean 'weather' are of critical importance.

Jason-2 reliably delivers detailed oceanographic data vital to our understanding of weather forecasting and climate change monitoring. The altimeters on Jason-2 are essential components of a global ocean observation system, providing co-located measurements of significant wave height, wind speed and sea surface topography.

Vital ocean data

Jason-2 provides data on the decadal (10-yearly) oscillations in large ocean basins, such as the Atlantic Ocean; mesoscale variability, and surface wind and wave conditions. Jason-2 measurements contribute to the European Centre for Medium-Range Weather Forecasts (ECMWF) satellite data assimilation, helping improve global atmosphere and ocean forecasting.

Altimetric data from Jason-2 have also helped create detailed decade-long global observations and analyses of the El Niño and La Niña phenomena, opening the way to new discoveries about ocean circulation and its effects on climate, and providing new insights into ocean tides, turbulent ocean eddies and marine gravity.

Information on the sea surface height enables the study of the growth and evolution of surface waves, in response to winds and tidal forcing, and one can derive the positions and intensities of ocean currents, eddies and thermal fronts.

Short-range ocean forecasts

Webcast about the Jason

Short range ocean forecasts are useful in a variety of applications:

  • Sustainable management of ocean resources.
  • Monitoring of fishing vessel and merchant shipping fleets.
  • Safety of people and property at sea.
  • Environmental protection.
  • Harbour management.
  • Sizing of port and maritime structures.
  • Management and monitoring of coastal resources and environments.
  • Tourism.

Seasonal ocean forecasting

Seasonal ocean forecasting is one of the most demanding and ambitious objectives. Seasonal forecasting aims to provide useful information about the climate that can be expected in the coming months. Having a precise knowledge of the ocean state is essential when trying to forecast what the climate will be like six months ahead. As altimetry is one of the most important tools for monitoring ocean dynamics it is a source of vital data for seasonal forecasting models. Altimetry factsheet (PDF, 147 KB)

Climate

The oceans and atmosphere store and exchange energy in the form of heat, moisture, and momentum. The ocean also contributes to carbon storage and oxygen production. Changes in the energy balance between the oceans and atmosphere play an important role in the planet's climate change. From the seasonal to the decadal, or even the centennial timeframe, knowledge about the ocean state and its influence upon the atmosphere is one of the keys to climate forecasting.

The oceans are affected by climate variations, as the sea-level rises and falls in response to their fluctuations. By continuing to provide long time-series of very precise observations of currents and sea-level, Jason-2 aids a better understanding of how oceans and climate interact.

Near real-time services

The Operational Geophysical Data Record (OGDR) is a real-time operational product specially developed for the Jason-2 mission. The OGDR will be the faster product delivered to the users, with a short delay of three to five hours. The product takes advantage of the DORIS navigator and of the on-board processing capabilities to provide geophysical data. The main geophysical variables in the OGDR product are: time; location; significant wave height; wind speed and the Sea Surface Height Anomaly derived from a very accurate rapid orbit. Important processing variables are also included in the product.

These are:

  • backscatter coefficients;
  • water vapour correction;
  • altimeter ranges; orbit data (altitude);
  • geophysical corrections;
  • geophysical references.

This product is essentially dedicated to marine meteorology applications. The primary purpose is to provide in near real-time data to meteorological organisations carrying out Nowcasting and operational wave forecasting, but it will also make data on sea surface height anomalies available for ocean users. The OGDR is processed at the EUMETSAT and NOAA ground centres.

Key user organisations include ECMWF, Météo-France, NOAA, Met Office and Met.no, the Norwegian Meteorological Institute, where significant wave heights are assimilated in their operational wave models. Several operational wave models are coupled to the global and regional Numerical Weather Prediction models, to provide a wave spectrum based surface roughness for ocean surface flux calculations. Altimeter wind speeds are used for validation.

Off-line services

The Interim Geophysical Data Record (IGDR) — this service provides sea surface data which is produced within one to one-and-a-half days of being recorded. This record includes analysed data on sea surface height, absolute dynamic topography and ocean geostrophic velocities for medium-range weather forecasting, seasonal forecasting and ocean weather applications. Key user communities include ECMWF, GMAO-NOAA, AOML-NOAA, MERSEA (EU), the Danish Meteorological Institute and Dutch clients for storm surge modelling. Sea level anomalies are assimilated in seasonal forecast systems and for validation of mesoscale variability. AOML-NOAA produces the Tropical Cyclone Heat Potential (TCHP) product, used for Cyclone intensity monitoring.

The Geophysical Data Record (GDR) — this service provides fully-validated data produced within three to four weeks of the events being recorded and covers sea surface height, principally for climate monitoring and climate modelling. The main users of this product are within the climate research community, for climate model verifications, for routine sea level station validation, and for the International Panel for Climate Change Assessment Report on rising sea levels.

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