Ocean Surface Topography Mission/Jason-2

Watching Over Our Ocean

National Aeronautics and Space Administration
Please call the Public Affairs Offices at NASA, NOAA, CNES or EUMETSAT

before contacting individual scientists at these organizations.

NASA Jet Propulsion Laboratory

Alan Buis, 818-354-0474, alan.buis@jpl.nasa.gov 

NASA Headquarters

Steve Cole, 202-358-0918, stephen.e.cole@nasa.gov

NASA Kennedy Space Center

George Diller, 321-867-2468, george.h.diller@nasa.gov 

NOAA Environmental Satellite, Data and Information Service

John Leslie, 301-713-2087, x174, john.leslie@noaa.gov 

CNES

Eliane Moreaux, 011-33-5-61-27-33-44, eliane.moreaux@cnes.fr 

EUMETSAT

Claudia Ritsert-Clark, 011-49-6151-807-609, claudia.ritsertclark@eumetsat.int 

NASA Web sites

http://www.nasa.gov/ostm

http://sealevel.jpl.nasa.gov/mission/ostm.html 

NOAA Web site

http://www.osd.noaa.gov/ostm/index.htm

CNES Web site

http://www.aviso.oceanobs.com/en/missions/future-missions/jason-2/index.html 

EUMETSAT Web site

http://www.eumetsat.int/Home/Main/What_We_Do/Satellites/Jason/index.htm?l=en

Content: Nicole Miklus

Design: Sally J. Bensusen

Editing: Alan D. Buis, Annie Richardson, Margaret Srinivasan, Rosemary Sullivant, Alan Ward

Cover image: NASA, CNES

Acknowledgments
Table of Contents

The Ocean in a Changing Climate ................................................

Mapping the Ocean ......................................................................

A Satellite Altimetry Family Tree ..................................................

TOPEX/Poseidon and Jason-1: Lessons Learned ...........................

OSTM/Jason-2: Continuing the Altimetry Legacy ........................

How It All Works: The “Nuts and Bolts” of OSTM/Jason-2 ..........

The Instruments ............................................................................

OSTM/Jason-2: How Is It Different? ............................................

The Future: Jason-3 and Beyond ...................................................

OSTM/Jason-2 Science Team ......................................................

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6

8

11

12

13

14

16

17

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4 OSTM I Watching Over Our Ocean

The Ocean in a Changing Climate 

We see it on the evening news; we witness it in 

our own backyards—our climate is changing. 

From heat waves to more devastating floods 

and hurricanes to melting glaciers and sea 

level rise, the effects of climate change are all 

around us. The vitality of crops, our drinking 

water supply, animal populations, the spread 

of diseases, and, ultimately, the rise and fall 

of civilizations are all influenced by climate. 

Scientists know that natural variability in 

Earth’s climate affects weather patterns, but 

it’s also increasingly clear that the burning of 

fossil fuels by humans is a major contributor to 

the changes we are experiencing. 

During the last century, carbon dioxide 

emissions caused by human activities have 

been the main contributor to the 0.6oC (1oF) 

increase in Earth’s average global air temperature—a seemingly small amount, but enough 

to cause global environmental impacts. It is 

unclear, though, how much warming will 

occur in the future and how widespread it 

will be. To predict how Earth’s climate will 

The image at right shows 

the dominant patterns for 

the change of sea level 

of the global ocean from 

1992 to 2008. The yellow and red regions illustrate that over most of the 

ocean, the sea level is rising at rates from 1-10 millimeters per year. The patterns of sea level rise are 

not uniform and are determined by the ocean circulation and the processes 

through which heat is absorbed and transported 

by the ocean. Credit: L. 

Fu, NASA JPL

continue to change, it is first necessary to 

understand what drives it.

The Ocean’s Role in Climate

The ocean is one of the biggest “drivers” of 

Earth’s climate system. Global climate is the 

result of a complex interplay between the 

atmosphere and ocean. The world ocean 

stores immense amounts of heat—much more 

than the atmosphere—and recirculates this 

energy around the planet in a process called 

the oceanic heat conveyor belt. The ocean covers more than 70 percent of Earth’s surface 

and absorbs a large amount of the energy our 

planet receives from the Sun. Solar energy 

is not distributed evenly over the surface, 

though. Equatorial regions receive more solar 

radiation than they emit back to space, while 

polar regions emit more radiation than they 

receive from the Sun. The ocean, along with 

the atmosphere, helps to move heat between 

the equator and the poles.

65

45

25

5

-5

-25

-45

-65

0 30 60 90 120 150 180 210 240 270 300 330 360

-10 -6 -2 2 6 10

Sea Level Anomaly (millimeters/year)

Image credit: WH Films
OSTM I Watching Over Our Ocean 5

Atmospheric winds blow across the ocean 

surface to create currents that swirl in gyres

around areas of high and low sea level. These 

currents release heat as they travel from the 

equator to the poles, and some of this heat 

is transferred to the atmosphere through 

evaporation over tropical and subtropical 

waters. As the currents lose heat, they begin 

to cool and become more dense, slowly sinking and spreading throughout the deep parts 

of the ocean. Eventually, they will reach the 

surface once again and perpetuate the cycle in 

this oceanic heat conveyor belt. In this way, 

the ocean regulates the temperature on our 

planet much like the thermostat in your home 

acts to warm or cool your surroundings.

The Ocean and Rising Temperatures

As global temperature rises, the excess heat 

is absorbed and stored in the upper layers of 

the ocean—a process that slows atmospheric 

warming. More than 80 percent of the heat 

from global warming over the past 50 years 

has been absorbed by the ocean. This heat, 

however, is not stored without consequence. 

Increased sea surface temperatures cause 

evaporation to intensify, introducing more 

The oceanic heat conveyor 

belt is also known as the 

Thermohaline Circulation. 

Thermohaline because 

these surface and deep 

currents are driven both by 

heat (“thermo”) and salinity 

(“haline”). It is estimated 

that the round trip journey 

of a single section of this 

conveyor belt can take from 

1,000 to 2,000 years. Image credit: NASA, adapted 

from the IPCC 2001 and 

Rahmstorf 2002.

Note: PSU stands for 

Practical Salinity Unit. 

One PSU is approximately 

equivalent to 1 gram of 

sea salt per kilogram of 

seawater.

water vapor—the most abundant greenhouse 

gas and one that’s 50 times as powerful as 

carbon dioxide—into the atmosphere. At the 

same time, warmer ocean temperatures cause 

the ocean’s volume to increase in a process 

called thermal expansion. The result is higher 

sea levels that threaten coastal communities 

and habitats. While we don’t know exactly 

how much more heat the ocean can absorb 

from global warming, it is already clear that 

significant changes in Earth’s hydrologic 

cycle and climate result from any excess storage of heat. 

With the evaporation rate higher, scientists 

have found that the salinity of the ocean 

is changing. Water in the polar regions is 

becoming fresher, while tropical waters are 

getting saltier. Changes in the salinity of the 

ocean can disrupt its circulation patterns, 

stalling the movement of heat and leading 

to global or regional cooling within several 

decades. Earth has experienced these abrupt 

climate changes throughout its history, with 

the most recent one—known as the Little Ice 

Age—triggered about 700 years ago. Charting 

the behavior of the ocean over time allows us 

to better foresee changes in Earth’s climate.

Salinity (PSU)

32 34 36 38
6 OSTM I Watching Over Our Ocean

Mapping the Ocean

Ocean Surface Topography

The ocean surface has highs and lows, just 

like the hills and valleys of Earth’s land 

depicted on a topographic map. The variations 

in height, called ocean surface topography, can 

be as much as 2 meters (6.5 feet) from place 

to place. 

Earth’s gravity field imposes a greater influence 

on sea surface height. By causing the sea 

surface to assume an irregular shape called 

the geoid, gravity is responsible for height 

differences of up to 200 meters (656 feet).

Ocean surface topography is determined by 

removing the effect of Earth’s gravity from 

the total sea surface height to reveal the 

2-meter variations caused by ocean circulation, 

temperature, and salt content. It is a valuable 

indicator of the ocean’s role in our climate, 

telling us where the ocean stores and transports heat and how 

it interacts with the 

atmosphere.

Accurate maps of 

ocean surface topography are crucial to 

understanding the 

ocean’s influence on 

our weather patterns and long-term 

climate. The dramatic 

impact that rising sea 

levels have on coastal 

regions is just one of 

many examples of 

how changes in the 

ocean greatly affect 

our society.

Altimetry

The height of the sea surface is measured 

with satellite altimetry. Radar altimeters 

measure the distance between the satellite 

and the sea surface by calculating the time it 

takes for a microwave pulse to reach the sea 

surface and travel back to the satellite. 

The measurements are corrected to account 

for anything that may delay the microwave 

pulses, such as water vapor in the lower 

atmosphere, free electrons in the upper atmosphere (ionosphere), and the dry air mass 

of the atmosphere. The result is remarkably 

precise sea surface levels—to within a few 

centimeters (about one inch) height.

Measurements of wave height, ocean current 

velocity and direction, and wind speed can 

also be obtained using satellite altimetry.

Satellite radar altimeter 

measurements of ocean 

surface topography are 

greatly improved by 

instruments that provide 

precision orbit determination. The Poseidon-3 

altimeter on OSTM/Jason-2 

is complemented by three 

such instruments: the 

GPSP, LRA, and DORIS. 

(See The Instruments section on page 14.) Image 

credit: NASA JPL

Image credit: Bo Qiu
OSTM I Watching Over Our Ocean 7

OSTM/Jason-2 map of 

wind speeds from July 4 

to July 14, 2008. Image 

credit: CNES

-10 -8 -6 -4 -2 0 2 4 6 8 10

Sea level Anomaly (centimeters)

 0 1.5 3 4.5 6 7.5 9 10.5 12 13.5 15

Altimeter Wind Speed (meters/second)

OSTM/Jason-2 map of sea 

level anomalies from July 

4 to July 14, 2008. Image 

credit: CNES
8 OSTM I Watching Over Our Ocean

A Satellite Altimetry Family Tree

The use of satellite altimetry to map the ocean 

surface began in 1973 with the launch of 

NASA’s Skylab, a space science and engineering laboratory sent into Earth orbit. Following 

Skylab, the GEOS-3 satellite carried the first 

spaceborne altimeter and was used to delineate the major trenches of the ocean. Subsequent satellites continued to explore the use of 

ocean altimetry and, in 1978, NASA’s Seasat 

provided never-before-seen data on Earth’s 

ocean. With Seasat, the resolution of ocean 

surface topography measurements increased 

dramatically. The mission provided a tantalizing glimpse into the many applications possible by monitoring the ocean from space.

Ushering in a new era marked by the long-term 

collection of ocean surface data, NASA and 

the French space agency, the Centre Nationale 

d’Etudes Spatiales (CNES), teamed up to 

launch the Ocean Topography Experiment 

(TOPEX)/Poseidon mission in 1992. TOPEX/

Poseidon began an international effort to characterize the world’s ocean and exceeded expectations with its extended lifespan. Measuring sea 

surface height over 95 percent of Earth’s ice-free 

ocean once every 10 days, TOPEX/Poseidon 

gathered oceanographic data with unprecedented accuracy (to within 4 centimeters—less than 

2 inches) for more than a decade. 

With the success of TOPEX/Poseidon, scientists recognized the importance of extending 

the time-series of ocean observation data for 

use in science and other ongoing applications 

as well as improvements in our ability to make 

long-term climate projections. Launched in 

2001, Jason-1 joined with TOPEX/Poseidon 

to obtain double global coverage until the 

earlier mission’s hardware failure in 2005. 

Jason-1, also a joint project between NASA 

and CNES, measures ocean surface topography to 3.3 centimeters (1.3 inches). Data 

from Jason-1 are available four days after 

being recorded and are used by weather and 

climate agencies for improved forecasting.

To further extend the record of Earth’s 

oceanographic data and enable greater data 

usage by the forecasting community, four organizations collaborated to launch the Ocean 

Surface Topography Mission on the Jason-2 

satellite (OSTM/Jason-2) in 2008. NASA, the 

National Oceanic and Atmospheric Administration (NOAA), CNES, and the European 

Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) worked 

together to develop and launch OSTM/

Jason-2. The altimeter aboard the OSTM/

Jason-2 satellite follows Jason-1 in its quest 

to continue mapping the ocean surface. With 

NOAA and EUMETSAT as newcomers to 

the ocean surface topography missions, both 

organizations will gain experience in the field 

by managing OSTM/Jason-2’s operation and 

data processing. NASA and CNES will maintain OSTM/Jason-2’s instruments.

Launched in 1978, Seasat 

(right) collected more data 

in 100 days than ships did 

in the previous 100 years. 

Image credit: NASA

Launched in 1992, TOPEX/

Poseidon (below) began an 

international effort to characterize the global ocean. 

Image credit: CNES
OSTM I Watching Over Our Ocean 9

OSTM/Jason-2 was launched on June 20, 

2008, from Vandenberg Air Force Base in 

California atop a United Launch Alliance 

Delta II rocket. At an operational orbit of 

1,336 kilometers (830 miles), the spacecraft

repeats its ground track every 10 days to cover 

95 percent of the world’s ice-free ocean. During the first six to nine months of its mission, 

OSTM/Jason-2 flies in line with Jason-1 

(approximately 55 seconds or 300 miles behind) 

while scientists compare the operation and 

accuracy of both satellites’ instruments and 

data products. Once the cross-calibration 

and validation are complete, Jason-1 is moved 

to a position parallel to OSTM/Jason-2, 

facilitating double global coverage of the 

world’s ocean.

Since Earth’s geoid influences ocean surface 

topography measurements, it’s important 

to have a clear picture of our planet’s shape. 

A “close relative” on the Altimetry Family 

Tree is the Gravity Recovery and Climate 

Experiment (GRACE). GRACE, launched 

in 2002, maps monthly variations in Earth’s 

gravity field and provides a closer approximation of the geoid or true physical figure 

of Earth. Gravity field variations reflect 

changes in ice mass in Greenland and Antarctica, ocean mass changes, water content 

in river basins on land, or changes caused 

by large earthquakes. Data from GRACE 

are critically important when it comes to 

obtaining an accurate measurement of 

ocean surface topography.

Satellite Altimetry Applications

The interdisciplinary study of Earth’s ocean 

is achieved through global partnerships of 

agencies such as NASA, NOAA, CNES, and 

EUMETSAT. By combining their expertise 

and experience, these agencies facilitate the 

vast study of ocean surface topography. As 

a result, satellite altimetry has contributed a 

wealth of information to the fields of oceanography, climatology, and meteorology.

The time series of sea surface height measurements, approaching sixteen years, has 

provided oceanographers and marine operators with an exceptional opportunity for new 

discoveries in both scientific research and 

operational applications. In combination 

with other data streams such as ocean color, 

winds, gravity, and ocean profiling floats, 

scientific researchers are discovering new 

ways to view ocean processes and are increasingly able to discern more intermediate-scale 

ocean structures and phenomena.

GRACE’s precise gravity 

measurements improve 

the accuracy of ocean 

altimetry data. Image 

credit: GFZ

The 12:46 a.m. launch of 

OSTM/Jason-2 from Vandenberg Air Force Base 

on June 20, 2008, enabled 

it to go into orbit directly 

behind Jason-1. Image 

credit: ULA
10 OSTM I Watching Over Our Ocean

Results from satellite 

altimetry missions 

have led to significant improvements 

in forecast accuracy. 

NOAA scientists 

routinely use satellite altimetry data 

to anticipate the 

weather-related 

effects of El Niño and 

La Niña events and 

the climatic effects of 

the Pacific Decadal 

Oscillation—a 20- to 

30-year-long ocean 

temperature shift 

between a “warm phase” and a “cool phase”. 

Data on the amount and distribution of heat 

in the ocean are used to predict hurricane 

frequency and intensity. This forecasting 

ability becomes increasingly important as we 

may see heightened hurricane activity with 

warming of the globe. 

By having access to data every several 

days, offshore industries can be prepared 

for rough weather that may interfere with 

operations or threaten safety. Information on ocean eddies—currents that bring 

up nutrients from deeper waters—and 

ocean temperature is used to follow animal 

migration patterns and evaluate coral 

reef health. The data can be used to map 

ocean currents and eddies, which have a 

major impact on coastal fisheries, offshore 

oil facilities, ocean shipping, and marine 

ecosystems. Private companies use and distribute altimetry data tailored specially for 

commercial and operational applications.

With the addition of OSTM/Jason-2, the 

methodologies of ocean altimetry measurements will transition from basic research and 

technology verification to these operational 

uses. The focus will move from research 

objectives to data applications that benefit 

society. Operation of the OSTM/Jason-2 

satellite will be turned over to the operational 

weather and climate agencies—NOAA in the 

United States and EUMETSAT, the European meteorological satellite agency. NASA and 

CNES will continue to support instrument 

and spacecraft operations and will archive 

select data from the mission. They will also 

continue to support an international science 

team that uses the data to conduct important 

ocean science studies. Again, many of the 

study objectives include benefits to society.

The applications of ocean surface topography 

are numerous and continue to grow as instrument sophistication and data processing 

capabilities are enhanced.

Global sea level has 

risen about 3 millimeters 

(0.1 inch) per year since 

TOPEX/Poseidon (on the 

left) began its precise 

measurement of sea surface height in 1993 and 

was followed by Jason-1 

in 2001. In this graph, the 

vertical scale represents 

globally averaged sea level in millimeters. Seasonal 

variations in sea level have 

been removed to show the 

underlying trend. Credit: 

University of Colorado

Seaturtle.org uses satellite 

altimetry data to study migratory routes of hawksbill 

turtles in relation to surface eddy fields in their 

ocean habitats. Image 

credit: E. van Wier
OSTM I Watching Over Our Ocean 11

TOPEX/Poseidon and Jason-1

Lessons Learned

While altimeters on early missions demonstrated that ocean surface topography 

could be measured from space, it wasn’t 

until TOPEX/Poseidon and Jason-1 that the 

importance of ocean monitoring became 

widely known. Perhaps most striking about 

what we’ve learned from TOPEX/Poseidon 

and Jason-1 is that our ocean is constantly changing.

From these missions, we’ve achieved our first 

glimpse of the global ocean—its seasonal 

current changes and large-scale oscillations—

and have been able to chart its changes over 

Variability of the ocean surface topography derived 

from radar altimeter measurements. The variability 

reflects the presence of 

ocean eddies. Data from 

TOPEX/Poseidon and European Remote Sensing 

(ERS) satellites; image processing by L. Fu, NASA JPL time. We can finally begin to understand 

how ocean circulation works and can use 

satellite data to test the accuracy of our 

computer models. We now know that 

the ocean has changed since the launch 

of TOPEX/Poseidon in 1992—it’s now 

warmer, sea level has risen, and ocean gyres 

have sped up and slowed down over a time 

span of 15 years. Without TOPEX/Poseidon 

and Jason-1, we’d still be very much in the 

dark about the ocean and limited in our 

ability to determine how its changes will 

impact our climate and society.

Sea Surface Height (cm)

0 10 20 30 40
12 OSTM I Watching Over Our Ocean

OSTM/Jason-2

Continuing the Altimetry Legacy

Hurricane Rita rapidly intensified to Category 5 status as it passed over the 

warm waters of the Loop 

Current in the Gulf of Mexico in September 2005. 

The storm diminished to 

Category 3 by the time it 

traveled over cooler waters. Data source: merged 

TOPEX/Poseidon, Jason-1, 

Geosat Follow-On (GFO), 

and Envisat altimeter data 

processed by the University of Colorado’s CCAR 

group. Image credit: University of Colorado

Argo profiling floats measure temperature, salinity, 

pressure, and current velocity of the ocean. When 

combined with sea surface height data from satellites, a complete description of the upper ocean is 

achieved. Image credit: 

Japan Coast Guard

Many oceanic phenomena take place over 

long time periods and require many years 

of continuous observations to study them. 

OSTM/Jason-2 will extend the important 

data time-series of ocean observations into a 

third decade and will provide scientists with 

the information they need to answer increasingly complex questions about how our ocean 

functions. The observations from OSTM/

Jason-2 open up new possible applications for 

satellite altimetry data while also improving 

upon the accuracy of existing applications.

With this new information, operational users, 

such as private companies and ocean/weather 

forecasting agencies, will be more confident 

of conditions predicted by their models. The 

accuracy of hurricane predictions will also 

increase, saving lives and property while 

assisting in disaster relief planning. Continuing 

to collect data on river and lake levels will 

help us to improve management of our water 

resources. Finally, offshore industries and the 

military rely on the latest marine data for their 

efficient operations and safe navigation and 

will benefit from OSTM’s observations.

The data from OSTM/Jason-2 will be used 

in conjunction with data sets from GRACE 

and Argo (a global array of 3,000 oceanprofiling floats) for comprehensive coverage 

of ocean salinity, temperature, velocity, and 

surface topography.

Florida

Cuba

Gulf of

Mexico

Texas

The globe image at right 

shows Jason-1 data indicating February 2008 La 

Niña conditions. Image 

credit: NASA
OSTM I Watching Over Our Ocean 13

has also been used for several other satellites, including the NASA/CNES CloudAerosol Lidar and Infrared Pathfinder 

Satellite (CALIPSO) mission. The OSTM/

Jason-2 platform has service and payload 

modules designed and adapted specifically 

for the mission. 

Weighing approximately 510 kilograms 

(1,124 pounds), OSTM/Jason-2 runs on 

500 watts of energy—enough to power 

about eight household light bulbs. The 

spacecraft collects its energy via eight solar 

panels, four on each solar wing array. 

OSTM/Jason-2 has a primary mission of 

three years, with a planned extended mission 

of two years. 

The payload of OSTM/Jason-2 is made 

up of five primary science instruments, 

supplied by NASA and CNES, and three 

“passenger” instruments, supplied by 

CNES and Japan.

How It All Works 

The “Nuts and Bolts” of OSTM/Jason-2

The OSTM/Jason-2 mission is based on 

the Jason-1 and TOPEX/Poseidon missions. 

The spacecraft design began with the 

selection of a spacecraft bus—the platform 

onto which the payload instruments are 

attached. OSTM/Jason-2’s bus is based on 

Thales’ PROTEUS low-Earth-orbit platform. PROTEUS is a French acronym that 

translates to “reconfigurable platform for 

observing, telecommunications, and scientific uses”. First used for Jason-1, this bus 

The OSTM payload (left)

is shown here fully integrated onto the PROTEUS 

spacecraft bus. Image 

credit: NASA

A technician oversees the 

attaching of the OSTM/

Jason-2 spacecraft to a tilt 

dolly inside the Astrotech 

processing facility at Vandenberg Air Force Base. 

Image credit: NASA 
14 OSTM I Watching Over Our Ocean

The Instruments 

The Poseidon-3 altimeter 

is OSTM/Jason-2’s main 

instrument. The AMR, DORIS, 

LRA, and GPSP provide 

data to improve the altimeter measurement. Image 

credit: NASA

The Primary Instruments

Poseidon-3 is OSTM/Jason-2’s altimeter 

and main instrument. It is an advanced version of the Poseidon-2 altimeter on Jason-1. 

Emitting pulses at two frequencies, Poseidon-3 

measures ocean surface topography by calculating the distance between the satellite and 

the sea surface. The Advanced Microwave 

Radiometer (AMR) improves the accuracy 

of Poseidon-3’s ocean surface topography 

measurements by correcting for water vapor 

in the atmosphere. To keep track of its 

velocity and place in orbit, OSTM/Jason-2 

employs the Doppler 

Orbitography and 

Radio-positioning 

Integrated by 

Satellite (DORIS) 

instrument. 

Poseidon-3 uses DORIS to help improve 

measurements over coastal zones, inland 

areas, and ice. Much like a Global Positioning System (GPS) unit helps you find your 

destination, the Global Positioning System 

Payload (GPSP) on OSTM/Jason-2 triangulates the spacecraft’s 

position at any given 

time with up to 12 

GPS satellites. The 

Laser Retroreflector 

Array (LRA) is a 

mirror array that is 

used with groundbased laser ranging 

stations to track the 

AMR

DORIS

GPSP

GPSP Poseidon-3 electronics

AMR

DORIS

Poseidon-3

Altimeter

LRA
OSTM I Watching Over Our Ocean 15

satellite. Several of OSTM/Jason-2’s primary 

instruments are complementary, performing 

similar functions to ensure that the satellite’s 

position is monitored precisely.

The Passenger Instruments

The passenger instruments on OSTM/Jason-2 

will be used to study additional topics of 

interest. The Environment Characterization 

and Modelisation-2 (Carmen-2) instrument 

and Light Particle Telescope (LPT) will 

examine how radiation influences the satellite’s components. With the Time Transfer by 

Laser Link (T2L2) instrument, scientists can 

compare and synchronize ground clocks with 

high accuracy. 

Data Products

NOAA, CNES, and EUMETSAT will process the raw data from OSTM/Jason-2 into 

data products and distribute them to users. 

Data will be grouped into three products: 

the Operational Geophysical Data Record 

(OGDR), the Interim Geophysical Data 

Record (IGDR), and the Geophysical Data 

Record (GDR). The OGDR consists of near 

real-time data, delivered to the user in less 

than three hours. Unique to OSTM/Jason-2, 

the OGDR is specially suited for near realtime forecasting. Meteorological agencies will 

be able to use surface wind speed, sea surface 

height, and wave data for atmospheric and 

oceanic predictions. Both the IGDR and 

GDR are “offline”, made up of data collected 

a few days or weeks prior to distribution. 

With data produced within one to one-anda-half days of being recorded, the IGDR is 

used in seasonal forecasting and to predict 

ocean weather five to seven days in advance. 

The GDR will be used in climate modeling 

and provides sea surface data within 60 days 

of being recorded.

LRA

T2L2 is an optical time 

transfer experiment on 

Jason-2. Using pulses of 

light, it allows synchronization of remote clocks on 

Earth and high-accuracy 

monitoring of the satellite’s 

clock. Image credit: G. 

Benjamin, CNES
16 OSTM I Watching Over Our Ocean

almost 50 percent closer to coastal regions—

where the majority of Earth’s population lives. 

This increased accuracy will provide data on 

the ever-changing coastal currents and sea 

level variation that impact population, trade 

and commerce, and tourism.

The international partnerships fostered by 

the development of OSTM/Jason-2 will 

bring Europe’s and America’s investments in 

satellite altimetry research toward fully functioning operations. Cooperation between 

countries and agencies is necessary for future 

Earth missions—without international 

cooperation, it will be difficult to collect 

the global data we need to understand 

climate change.

OSTM/Jason-2

How Is It Different?

OSTM/Jason-2 continues the important 

time-series of ocean 

observations, adding 

to the 16 years of 

data collected by 

TOPEX/Poseidon 

and Jason-1. Operational weather forecasters will observe 

changes in ocean 

conditions more 

quickly than ever 

before and will be 

able to make more 

accurate predictions of short-term 

weather events.

Scientists will have 

the long-term data 

that they need to 

predict large-scale 

events like El Niño 

and La Niña, and to understand how ocean 

circulation is affected by climate change. Advancements made to instruments on OSTM/

Jason-2 will allow observations to be made 

These data globes, created with radar altimeter 

measurements from TOPEX/

Poseidon and Jason-1, represent 16 years of average 

annual sea-surface height 

anomalies for the period 

from 1992 to 2007. Image 

credit: NASA JPL

On December 26, 2004 a 

Magnitude 9 earthquake 

struck off the coast of Indonesia and triggered 

a devastating tsunami. 

Four altimetry satellites--

Jason-1, Topex/Poseidon, 

Envisat and GFO--passed 

over the Indian Ocean between two and six hours 

after this event and collected an abundance of 

data that has been used to 

help refine tsunami wave 

propagation and dissipation models and improve 

tsunami warning systems. 

Image credit: NASA JPL

1992 1993 1994

2000

1996 1997 1998 1999

1995

2004 2005

2001 2002 2003

2006 2007
OSTM I Watching Over Our Ocean 17

The Future

JasonJason-3 and Beyond...

Targeted for launch in 2013, Jason-3 will 

follow OSTM/Jason-2’s legacy of ocean 

monitoring from space. NOAA and

EUMETSAT will use their experience 

with OSTM/Jason-2 to design and implement Jason-3. The operation of Jason-3 will 

prevent any gap in ocean surface topography 

data and supply weather forecasters with 

the information they need. Jason-3 will also 

ensure that accurate predictions of sea level 

change and the accompanying impact to 

coastal populations can be made. 

Next-generation satellites will seek to 

answer questions about the relationship 

between ocean and terrestrial waters (rivers, 

lakes, and wetlands) in the hydrologic cycle, 

as well as the small-scale ocean processes 

The SWOT spacecraft, 

shown here in an artist’s 

conception, will make accurate measurements of mesoscale ocean features and 

surface water parameters. 

Image credit: NASA JPL

affecting climate change. One of the satellites planned to do this, the Surface Water 

Ocean Topography Mission (SWOT), will 

help us to manage our water resources in 

the face of climate change. 

Satellite altimetry missions have already 

radically changed our understanding of the 

ocean and its role in Earth’s climate. From 

the weather forecast on your vacation to 

the beach to the predicted ferocity of the 

next hurricane, ocean surface topography 

measurements are ingredients essential to 

planning our lives. With data from OSTM/

Jason-2 and missions that follow, we will be 

even better equipped to assess future climate 

change and how we will safely respond to it.

The Columbia River-Pacific 

Ocean boundary. Note the 

color contrast where river 

water and ocean water 

meet. Image credit: NOAA
18 OSTM I Watching Over Our Ocean

Ocean Surface Topography Mission Science Team

Andersen, Ole B.

Danish National Space Center

(DNSC)

Denmark

Arnault, Sabine

Laboratoire d’Océanographie et du 

Climat: Expérimentations et Approches 

Numériques (LOCEAN)-IRD

France

Becker, Matthias

Technische Universitat Darmstadt

Germany

Benjamin, Juan José

Technical University of Catalonia

Spain

Bertiger, William

California Institute of Technology-JPL

U.S.

Bingham, Rory

Proudman Oceanography Laboratory

U.K.

Birkett, Charon

University of Maryland-College Park

U.S.

Birol, Florence

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Blanc, Frédérique

Collecte Localisation Satellites (CLS)

France

Bonnefond, Pascal

Observatoire de la Côte d'Azur-GEMINI

France

Bosch, Wolfgang

Deutsches Geodätisches 

Forschungsinstitut (DGFI)

Germany

Brown, Shannon

California Institute of Technology-JPL

U.S.

Callahan, Philip

California Institute of Technology-JPL

U.S.

Cazenave, Anny

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Chapron, Bertrand

L’Institut Francais de Recherche pour 

l’Exploitation de la Mer (IFREMER)

France

Chelton, Dudley

Oregon State University

U.S.

Cretaux, Jean-François

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Dadou, Isabelle

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

de Mey, Pierre

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Dombrowsky, Eric

Mercator Ocean

France

Dorandeu, Joël

Collecte Localisation Satellites (CLS)

France

Emery, William

University of Colorado at Boulder

U.S.

Eymard, Laurence

Laboratoire d’Océanographie et du 

Climat: Expérimentations et Approches 

Numériques (LOCEAN)

France

Fernandes, Joana

Faculdade de Ciencias-Universidade do Porto

Portugal

Gourdeau, Lionel

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Griffin, David

Commonwealth Scientific and Industrial 

Research Organisation (CSIRO)

Australia

Haines, Bruce

California Institute of Technology-JPL

U.S.

Han, Weiqing

University of Colorado at Boulder

U.S.

Hoeyer, Jacob

Danish Meteorological Institute (DMI)

Denmark

Ichikawa, Kaoru

Kyushu University

Japan

Janssen, Peter

European Centre for Medium-Range 

Weather Forecasts (ECMWF)

U.K.

Jayne, Steven

Woods Hole Oceanographic Institution

U.S.

Kelly, Kathryn

University of Washington

U.S.

Knudsen, Per

Danish National Space Center (DNSC), 

Denmark

Lagerloef, Gary

Earth and Space Research

U.S.

Larnicol, Gilles

Collecte Localisation Satellites (CLS)

France

Lazar, Alban

Laboratoire d’Océanographie et du 

Climat: Expérimentations et Approches 

Numériques (LOCEAN)

France
OSTM I Watching Over Our Ocean 19

Leben, Robert

University of Colorado at Boulder

U.S.

Lefevre, Jean-Michel

Meteo France

France

Legresy, Benoît

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Lemoine, Frank

NASA/Goddard Space Flight Center

U.S.

Maximenko, Nikolai

University of Hawaii

U.S.

Mertikas, Stelios

Technical University of Crete

Greece

Miller, Laury

NOAA/NESDIS/ORA

U.S.

Mognard, Nelly

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Morrow, Rosemary

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Naeije, Mark

Delft Institute for Earth-Oriented Space 

Research (DEOS)

Netherlands

Nerem, Robert

University of Colorado at Boulder

U.S.

Park, Young-Hyang

Muséum National d’Histoire Naturelle

France

Pascual, Ananda

Institut Mediterrani d’Estudis Avançats, 

Instituto Mediterraneo de Estudios 

Avanzados (CSIC-UIB)

Spain

Pavlis, Erricos

University of Maryland-Baltimore

U.S.

Penduff, Thierry

Laboratoire des Ecoulements 

Géophysiques et Industriels (LEGI)

France

Ponte, Rui

Atmospheric & Environmental Research, Inc.

U.S.

Provost, Christine

Laboratoire d’Océanographie et du 

Climat: Expérimentations et Approches 

Numériques (LOCEAN)

France

Qiu, Bo

University of Hawaii

U.S.

Quartly, Graham

National Oceanography Center (NOC)

U.K.

Quilfen, Yves

Institut Français de Recherche pour 

l’Exploitation de la Mer (IFREMER)

France

Radenac, Marie-Hélène

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Ray, Richard

NASA/Goddard Space Flight Center

U.S.

Rhines, Peter

University of Washington

U.S.

Roblou, Laurent

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Rosmorduc, Vinca

Collecte Localisation Satellites (CLS)

France

Shroeter, Jens

Alfred Wegener Institute

Germany

Song, Y. Tony

California Institute of Technology-JPL

U.S.

Strub, Paul

Oregon State University

U.S.

Tailleux, Rémi

Reading/Laboratoire des Ecoulements 

Géophysiques et Industriels (LEGI)

France

Testut, Laurent

Laboratoire d’Etudes en Geophysique et 

Oceanographie Spatiale (LEGOS)

France

Vandemark, Douglas

University of New Hampshire

U.S.

Verron, Jacques

Laboratoire des Ecoulements 

Géophysiques et Industriels (LEGI)

France

Vigo, Isabelle

Universidad de Alicante

Spain

Vivier, Frédéric

Laboratoire d’Océanographie et du 

Climat: Expérimentations et Approches 

Numériques (LOCEAN)

France

Wilkin, John

Rutgers, The State University

U.S.

Wunsch, Carl

Massachusetts Institute of Technology

U.S.

Yahia, Hussein

Institut National de Recherche en 

Informatique et en Automatique (INRIA)

France

Zanifé, Ouan-Zan

Collecte Localisation Satellites (CLS)

France

Zlotnicki, Victor

California Institute of Technology-JPL

U.S.
National Aeronautics and Space Administration

Jet Propulsion Laboratory

California Institute of Technology

4800 Oak Grove Drive

Pasadena, Calif. 91109-8099

http://www.jpl.nasa.gov

http://www.nasa.gov/ostm

http://sealevel.jpl.nasa.gov/mission/ostm.html

www.nasa.gov

NP-2008-10-052-GSFC