JASON-3 Press Kit

The history of satellite altimetry missions started in 1992 with the launch of the TOPEX/Poseidon mission—a joint NASA and CNES mission. This mission was followed by the launch of Jason-1 in 2001 and Jason-2 in 2008. TOPEX/Poseidon measured the height of the ocean to an accuracy of 4.2 cm, enabled scientists to forecast the 1997–98 El Niño cycle, and improved the understanding of ocean circulation and its effect on climate. Jason-1 was a NASA/CNES follow-on to TOPEX/Poseidon in the 66o inclination orbit. It used a different spacecraft bus and upgraded instruments, improving the accuracy of sea surface height measurements to 3.3 cm. Data for both missions was available through CNES and NASA/JPL.

Jason-2, also known as the Ocean Surface Topography Mission, was the next altimetry follow-on mission. The Jason-2 mission expanded the NASA/CNES partnership to include NOAA and EUMETSAT. NOAA and EUMETSAT’s participation added an operational component to what had been primarily a research mission. CNES handed operations over to NOAA after Jason-2 completed its on-orbit commissioning, and NOAA and EUMETSAT were responsible for data processing, archiving and distribution.

This international cooperation continues with Jason-3. NOAA and EUMETSAT are focused on the operational ocean weather benefits of Jason-3, while NASA and CNES are focused on the ocean climatology research benefits, continuing the data record of global ocean surface topography. Similar to Jason-2, NOAA will manage operations after launch, and NOAA and EUMETSAT will provide data distribution services.

The history of satellite altimetry missions started in 1992 with the launch of the TOPEX/Poseidon mission—a joint NASA and CNES mission. This mission was followed by the launch of Jason-1 in 2001 and Jason-2 in 2008. TOPEX/Poseidon measured the height of the ocean to an accuracy of 4.2 cm, enabled scientists to forecast the 1997–98 El Niño cycle, and improved the understanding of ocean circulation and its effect on climate. Jason-1 was a NASA/CNES follow-on to TOPEX/Poseidon in the 66o inclination orbit. It used a different spacecraft bus and upgraded instruments, improving the accuracy of sea surface height measurements to 3.3 cm. Data for both missions was available through CNES and NASA/JPL.

Jason-2, also known as the Ocean Surface Topography Mission, was the next altimetry follow-on mission. The Jason-2 mission expanded the NASA/CNES partnership to include NOAA and EUMETSAT. NOAA and EUMETSAT’s participation added an operational component to what had been primarily a research mission. CNES handed operations over to NOAA after Jason-2 completed its on-orbit commissioning, and NOAA and EUMETSAT were responsible for data processing, archiving and distribution.

This international cooperation continues with Jason-3. NOAA and EUMETSAT are focused on the operational ocean weather benefits of Jason-3, while NASA and CNES are focused on the ocean climatology research benefits, continuing the data record of global ocean surface topography. Similar to Jason-2, NOAA will manage operations after launch, and NOAA and EUMETSAT will provide data distribution services.

The Jason series of satellites use a technique called “radar altimetry” to measure sea surface variations. Jason-3’s radar altimeter measures the round-trip travel time of microwave pulses that it bounces off the sea surface. From this data, the distance between the satellite and sea surface can be determined. This measurement requires that the precise orbit height of the satellite is known, which is why Jason-3 has on board a combination of three orbit tracking systems. Meanwhile, a radiometer instrument on-board the satellite measures how the radar waves are slowed by the presence of water vapor in the atmosphere. In addition to sea surface height, the shape of the returned radar pulses also gives information on wind speed and significant wave height.

Altimetry measurements employ a different kind technique for data collection than is used by other NOAA satellites, which measure atmospheric conditions, space environment conditions, as well as imaging over land and sea, by measuring radiation at particular wavelengths.

If you have been on a boat, you know that the ocean surface is not flat. It ripples and undulates due to wind and waves, rises with the tidal pull of the moon, expands and contracts as it heats and cools, and billows due to circulation patterns. The ocean surface can vary in height by as much as 2 meters from one place to the next.

By measuring sea surface height and comparing it to what the ocean surface of Earth would be if the ocean were at rest (the geoid), scientists can characterize small- and large-scale changes over weeks and years. Sea surface height is a measure used to study sea level rise—a critical factor in understanding Earth’s dynamic climate. Sea surface height data is also used to study hurricanes, El Niño and La Niña, eddies, and ocean boundary currents. NOAA will use this data from Jason-3 primarily for operational purposes, i.e., monitoring and forecasting, but Jason-3 data will also be used for climate variability research, adding to a record of satellite altimetry data that began in 1992.

Jason-3 data supports hurricane intensity forecasting used to issue warnings and plan evacuations, high wave warnings used by ship operators, and ocean modeling that provides surface current information used by commercial fishing operators and off-shore facilities like oil platforms and ocean wind power farms. Jason-3 supports the NOAA/NESDIS mission to protect life and property.

Since the launch of TOPEX/Poseidon in 1992, scientists have amassed a continuous record of precise sea-surface height data for studying global ocean circulation and the connection to Earth’s climate. While the global sea surface temperature data record dates back further, it is not as closely related to ocean dynamics as ocean surface topography measured by the Jason series of satellites.

Data from the Jason missions has improved our ability to forecast weather and climate, including improved El Niño predictions, and the scientific benefits have been tremendous. Furthermore, without the continuation of this record, ocean weather models will stop functioning. The following are some research areas that have benefited directly from Jason data:

Hurricane Forecasting: The National Hurricane Center uses Jason data to derive ocean heat content, which is a key factor in forecasting hurricane intensity. Beginning in 2002, daily OHC analyses have been generated at the NHC. These analyses are used qualitatively for the official NHC intensity forecast and quantitatively to adjust the Statistical Hurricane Intensity Prediction Scheme (SHIPS) model.

Climate Forecasting and Ocean Variability: The National Weather Service Climate Prediction Center uses Jason observations to initialize the seasonal El Niño and La Niña forecasts. By observing year-to-year variability, like El Niño in the Pacific, scientists have discovered longer patterns of ocean variability that operate on decadal scales.

Sea Level Change: The over 20-year record of altimetry data from Jason satellites shows sea level rising at about 3 mm/year since 1993, nearly twice as fast as the previous century. The global rate of sea level rise has been estimated from altimetry observations to be approximately 2/3 due to ice melt and 1/3 due to ocean warming. These increases place coastal and low lying communities at risk during storm surge.

Ocean Models: Jason data has revolutionized ocean modeling. For example, TOPEX/Poseidon data guided the development of the first model able to simulate the precise course of the Gulf Stream. Accurate estimates of currents from these models are used in day-to-day marine, fisheries and off-shore operations, as well as search and rescue operations.

Deep Ocean Circulation: Jason-1 data have been combined with data from NOAA’s Argo program, which is an international ocean-observing program of over 3,500 ocean floats deployed in global ocean drifts at predetermined depths. These floats gather approximately 120,000 temperature, salinity and depth profiles throughout the world’s oceans every year. Combined with Jason observations, the information gathered by Argo floats allow for a better understanding of ocean dynamics, ocean warming and ocean chemistry.