1. ESA and GODAE Ocean View
Dr Stephen Briggs,
Head, Earth Observation Planning and Co—ordination
Third GODAE Ocean View Science Team Meeting, ESA HQ Paris
November 15th 2011

2. ESA Facts and Figures Over 40 years of experience
18 Member States, 19 in 2011
Five establishments in Europe, about staff
4 billion Euro budget (2011)
Over 70 satellites designed, tested and operated in flight
17 scientific satellites in operation
Six types of launcher developed
Celebrated the 200th launch of Ariane in February 2011

3. Activities ESA is one of the few space agencies in the world to
combine responsibility in nearly all areas of space activity.
Space science
Human spaceflight
Exploration
Earth observation
Launchers
Navigation
Telecommunications
Technology
Operations

4. ESA’s Earth Observation Toolkit

5. The development of Earth observation in Europe: ESA’s Living Planet Programme
ENVISAT
17/3/2009
16/7/2009
08/4/2010
Sentinel 1
Sentinel 2
Sentinel 4
Sentinel 5/5P
Sentinel 3
MSG/MTG
Mid 2013
MetOp
End 2013
There is an ever increasing demand for reliable EO data and ESA’s Living Planet Program (established in 1995) responds to this high demand.
The programme comprises a science driven element, the Earth Explorer missions, and an operational Earth Watch element.
The Earth Explorer missions are designed to address key scientific challenges identified by the science community. Currently there are six missions in this category 3 already launched, GOCE >> Gravity -- CRYOSAT >> Ice -- SMOS
and 3 are under development. ADM >> Wind -- Earth CARE >> Cloud and Aerosol --
SWARM >> Magnetic Field
3 candidate Earth explorer 7 missions are undergoing assessment and feasibility study:
BIOMASS >> forest biomass -- CoReH2O (Cold Regions Hydrology High-Resolution Observatory) snow / ice at high spatial resolution -- PREMIER 3D fields of atmospheric composition in upper troposphere and lower stratosphere between 5 and 25 km above the surface of the Earth.
One of these missions will be selected by this user driven competition and will be launched in 2016.
Earth Watch includes the well-established meteorological missions operated by our European partner organisation EUMETSAT. In addition, the GMES Sentinel missions will collect robust, long-term climate-relevant datasets.
End 2013
BIOMASS
CoReH2O
PREMIER 3 Core Candidate Earth Explorer 7 missions
CarbonSat & Flex in Explorer Opportunity Mission Candidates

6. Scientific challenges for ESA’s LPP
SP-1304 Updated Science Strategy for ESA’s LPP, after broad user consultation
Emphasis on the Earth System Approach, where interactions and interfaces between different parts of the Earth system are fundamental
Understand the impact of human activities on natural Earth processes
The Challenges of the Oceans
Challenge 1: Quantify the interaction between variability in ocean dynamics, thermohaline circulation, Sea level, and climate.
Challenge 2: Understand physical and bio-chemical air/sea interaction processes.
Challenge 3: Understand internal waves and the mesoscale in the ocean, its relevance for heat and energy transport and its influence on primary productivity.
Challenge 4: Quantify marine-ecosystem variability, and its natural and anthropogenic physical, Biological and geochemical forcing.
Challenge 5: Understand Land/Ocean interactions in terms of natural and anthropogenic forcing
Challenge 6: Provide reliable model- and data-based assessments and predictions of the past, present and future state of the ocean.
Focus on:
Hydrosphere
Atmosphere
Geosphere
Cryosphere
Biosphere
Available from

7. ESA: thousands of scientific projects
L’Aquila 2009
Hurricane Katrina
Tectonic uplift (Andaman)
Arctic 2007
Bam earthquake
First images
CO2 map
Chlorophyll concentration
Serving 5000 scientific projects
and
many operational users (including GMES Services)
B-15A iceberg
Ozone hole 2003
Prestige tanker oil slick
Mar 02
Launch
Envisat Symposium
Salzburg (A)
Envisat Symposium
Montreux (CH)
Living Planet Symposium
Bergen (N)
and many workshops dedicated to specific Envisat user communities
Sep 04
Apr 07
Jun 10

8. Altimetry: A foundation for ocean forecasting
ERS1  ERS2  ENVISAT  CryoSat  Sentinel-3
RA  RA  RA2  SIRAL  SRAL
Altimeter measurements have improved our understanding of both the dynamics and thermodynamics of western
boundary currents by providing a synoptic view of the current systems and their interannual
variations, and allowed scientists to quantify eddy-induced salt and heat transport, and seasonal
and interannual variations in eddy kinetic energy. Altimeter measurements have also been used
to map eddies, quantify their amplitudes and diameters, track their trajectories, and examine their
eddy dynamics and roles in the ocean processes and climate variability. Recent advances in
satellite altimetry, in synergy with other remote sensing techniques, constrain the uncertainty of
mechanic energy driving meridional overturning circulation which regulates climate change.
Moreover, altimetry has discovered a surprising sea level anomaly propagation speed which
challenges the existing linear Rossby wave theory, and revealed the presence of elusive zonal
fronts and jets in the ocean
DEM, Tides,
River and lake
Heights, …
Sea Surface Height
Wind and Waves
Mean Sea level

9. SST ERS1  ERS2  ENVISAT  Sentinel-3 ATSR1  ATSR2  AATSR  SLSTR
SST-VC
ERS  ERS  ENVISAT  Sentinel-3
ATSR1  ATSR2  AATSR  SLSTR
Improvements in data assimilation of SST:
Better ocean dynamics (fundamental variable)
Climate (seasonal/decadal prediction)
Better ocean/weather forecasts

10. Ocean Colour ENVISAT MERIS  Sentinel-3 OLCI
Improvements in data assimilation of
Ocean colour:
Better Water quality indicators
Better ecosystem management
Climate (carbon cycle)
Pollution management

11. GOCE: ESA’s Gravity Mission
The Gravity field and steady-state
Ocean Circulation Explorer (GOCE)
Launched 17th March 2009!!
GOCE will provide a high-accuracy global model of the Earth's gravity field and geoid to improve our understanding of ocean circulation, ice motion, sea-level change and Earth interior processes. GOCE will also make significant advances in the field of geodesy and surveying.
ESA's Gravity field and steady-state Ocean Circulation Explorer (GOCE) has been developed to bring about a whole new level of understanding of one of the Earth's most fundamental forces of nature – the gravity field.   Dubbed the 'Formula 1' of spacecrafts, this sleek high-tech gravity satellite embodies many firsts in terms of its design and use of new technology in space to map Earth's gravity field in unprecedented detail. As the most advanced gravity space mission to date, GOCE will realise a broad range of fascinating new possibilities for the fields of oceanography, solid Earth physics, geodesy and sea-level research, and significantly contribute to furthering our understanding of climate change.     Although invisible, gravity is a complex force of nature that has an immeasurable impact on our everyday lives. It is often assumed that the force of gravity on the surface of the Earth has a constant value, but in fact the value of 'g' varies subtly from place to place. These variations are due to a number of factors such as the rotation of the Earth, the position of mountains and ocean trenches and variations in density of the Earth's interior.
Mapping the GEOD as never before 
Over its lifetime of about 20 months, GOCE will map these global variations in the gravity field with extreme detail and accuracy. This will result in a unique model of the geoid, which is the surface of equal gravitational potential defined by the gravity field – crucial for deriving accurate measurements of ocean circulation and sea-level change, both of which are affected by climate change. GOCE-derived data is also much needed to understand more about processes occurring inside the Earth and for use in practical applications such as surveying and levelling.
GOCE takes six simultaneous measurements of the gravity field
Since the gravitational signal is stronger closer to Earth, the 'arrow-like', five-metre long GOCE satellite has been designed to cut through of what remains of the Earth's atmosphere at just 250 km above the surface of the planet. This low-orbiting spacecraft is the first mission to employ the concept of gradiometry - the measurement of acceleration differences over short distances between an ensemble of proof masses inside the satellite.   GOCE is equipped with three pairs of ultra-sensitive accelerometers arranged in three dimensions that respond to tiny variations in the 'gravitational tug' of the Earth as it travels along its orbital path. Because of their different position in the gravitational field they all experience the gravitational acceleration of the Earth slightly differently. The three axes of the gradiometer allow the simultaneous measurement of six independent but complementary components of the gravity field.
Although the gradiometer forms the heart of the satellite, to measure gravity there can be no interference from moving parts so the entire spacecraft is actually one extremely sensitive measuring device.   Mission objectives
to determine gravity-field anomalies with an accuracy of 1 mGal (where 1 mGal = 10–5 ms–2).
to determine the geoid with an accuracy of 1-2 cm.
to achieve the above at a spatial resolution better than 100 km.
Its objectives are to improve understanding of:
global ocean circulation and transfer of heat
physics of the Earth’s interior (lithosphere & mantle)
sea level records, topographic processes, evolution of ice sheets and sea level change

12. GOCE gravity field
meters

13. Results – Mean Dynamic Topography
1.4 m
-1.4
The GOCE MDT display the well-known features with enhanced resolution and sharpened boundaries. => Compute surface geostrophic currents (u,v)
(Knudsen et al. 2011)

14. Gulf Stream:
1.0 m
-1.0 40
cm/s
The GOCE (MDT, top left) and derived current speeds (top right) compared to GRACE current (lower left). Cf Maximenko (2009) (lower right)

15. Aghulas:
1.4 m
-1.4 40
cm/s
The GOCE MDT and derived current speeds (upper left and right) Speeds from a GRACE derived MDT (lower left) Speeds from Maximenko (2009) (lower right)

16. GOCE was included in the Top 10 scientific results of 2010 by Nature
Self explanatory

17. CryoSat2: ESA’s Ice Mission
Launched 8th April 2010
Its objectives are to improve our understanding of:
- thickness and mass fluctuations of polar land and marine ice
- to quantify rates of thinning/thickening due to climate variations
- Instrument: Ku band SIRAL (SAR Interferometric Radar Altimeter).
CryoSat will precisely measure ice thickness changes on both land and sea to provide conclusive evidence of whether there is a trend towards diminishing polar ice cover, and in the process enhance our understanding of the relationship between ice and global climate.
The question of whether global climate change is causing the polar ice caps to shrink is one of the most hotly debated environmental issues we currently face. By monitoring precise changes in the thickness of the polar ice sheets and floating sea ice, CryoSat-2 aims to answer this question.   The go-ahead to build and launch the CryoSat-2 mission came in February 2006 after the loss of the first CryoSat in October 2005 due to a launch failure. The mission's objectives remain the same as before – to measure ice thickness on both land and sea very precisely to provide conclusive proof as to whether there a trend towards diminishing polar ice cover, furthering our understanding of the relationship between ice and global climate. CryoSat-2 is due for launch in 2009.
It is now generally agreed that the Earth's atmosphere is getting warmer, and although the impact of climate change is expected to be amplified at the poles, it is extremely difficult to predict what effect this is having on the polar ice cover. On one hand, recent years have already seen record summer reductions, in extent and concentrations, of sea ice in the Arctic. In Antarctica, giant icebergs have calved and part of the Larsen ice shelf has disintegrated. However, on the other hand, ships have recently been trapped for weeks in unusually heavy Antarctic pack ice conditions.     From an altitude of just over 700 km and reaching latitudes of 88°, CryoSat-2 will monitor precise changes in the thickness of the polar ice sheets and floating sea ice. The observations made over the three-year lifetime of the mission will provide conclusive evidence of rates at which ice cover may be diminishing.   Fundamentally, there are two types of polar ice – the ice that floats in the oceans and the ice that lies on land. Not only do these two forms of ice have different consequences for our planet and its climate, they also pose different challenges when trying to measure them from space. Floating sea iceSea ice is relatively thin – up to a few metres thick, but, it influences regional temperature and the circulation of ocean currents, and consequently the Earth's climate. CryoSat-2 will acquire precise measurements of the thickness of floating sea ice so that annual variations can be detected.
Ice-shelf break up
In contrast, the ice sheets that blanket Antarctica and Greenland are several kilometres thick. It is the growth and shrinkage of these ice masses that have a direct influence on sea level. The chosen approach to measuring these vast thicknesses is to determine the height of the surface accurately enough to detect small changes.   To meet the challenges of measuring ice, CryoSat-2 will carry a sophisticated radar altimeter called SIRAL (Synthetic Aperture Radar Interferometric Radar Altimeter). It is based on heritage from existing instruments, but with several major enhancements designed to overcome the difficulties intrinsic to the precise measurement of ice surfaces.
CryoSat-2's primary payload is the SAR/Interferometric Radar Altimeter (SIRAL), which has extended capabilities to meet the measurement requirements for ice-sheet elevation and sea-ice freeboard. CryoSat-2 will also carry three star trackers for measuring the orientation of the baseline. In addition, a radio receiver called Doppler Orbit and Radio Positioning Integration by Satellite (DORIS) and a small laser retroreflector ensures that CryoSat-2's position will be accurately tracked.   Unlike conventional radar altimeters, where the interval between pulses is about 500 μs, the CryoSat-2 altimeter will send a burst of pulses with an interval of only 50 μs between them. The returning echoes will be correlated, and by treating the whole burst at once, the data processor can separate the echo into strips arranged across the track by exploiting the slight frequency shifts (caused by the Doppler effect) in the forward- and aft-looking parts of the beam. Each strip is about 250 m wide and the interval between bursts is arranged so that the satellite moves forward by 250 m each time. The strips laid down by successive bursts can therefore be superimposed on each other and averaged to reduce noise. This mode of operation is called the Synthetic Aperture Radar, or SAR mode.  
Phase difference between returning radar waves
In order to measure the arrival angle, a second receive antenna is activated to receive the radar echo with two antennas simultaneously. When the echo comes from a point not directly beneath the satellite there will be a difference in the path-length of the radar wave, which will be measured. Simple geometry provides the angle between the baseline, joining the antennas, and the echo direction.  
Knowledge of the precise orientation of the baseline and the two receiving antennas is essential for the success of the mission. CryoSat-2 will measure this baseline orientation using the oldest and most accurate of references – the position of the stars in the sky. Three star trackers are mounted on the support structure for the antennas. Each containes a camera, which will take up to five pictures per second. The images will be analysed by a built-in computer and compared to a catalogue of star positions.   The altimeter makes a measurement of the distance between the satellite and the surface of the Earth. This measurement can not be converted into the more useful measurement of height of the surface until the position of the satellite is accurately known.

18. Arctic Ocean Mean Dynamic topography (S. Laxon & D. Wingham, UCL)
Cryosat can view much more of the Arctic than other missions due to the high inclination of the orbit
Most recent data highlight the MDT using Cryosat data
(Credit:BBC)
Laxon et al: The Arctic is widely cited as the “canary in the coal mine” of climate change and the rapid reduction in the sea ice extent has been measured by passive microwave satellites since the 1970s. However, it was not until in 1993, following the launch ERS1 in 1991, that sea ice thickness could be calculated using data from its radar altimeter. The radar altimeters on ERS2 and Envisat have continued and improved these measurements. We are now in the position where both changes to the sea ice thickness and the effect of these changes on the underlying ocean can be assessed from these data. The radar altimeters onboard these ESA satellites measure both the sea ice freeboard and the elevation of the ocean surface, from which sea ice thickness and the time-variant sea surface topography can be calculated. We present the most recent update of changes to the ice covered Arctic, 

19. Arctic Ocean sea ice thickness from Cryosat (University College London)
The first map of sea-ice thickness from ESA’s CryoSat mission
Data from January and February 2011have been used to show the thickness of the ice as it approaches its annual maximum.
Thanks to CryoSat’s orbit, ice thickness close to the North Pole can be seen for the first time.

20. Arctic Sea Ice Extent, 14 Sept 2011 (Envisat + AMSR) Courtesy
ESA, NASA,
Univ Bremen

21. SMOS: Soil Moisture and Ocean Salinity Mission
Launched 2nd Nov 2009!!
Its objectives are:
to provide global maps of soil moisture and ocean salinity for hydrological studies
to advance our understanding of the freshwater cycle
to improve climate, weather and extreme-event forecasting
Instrument: Microwave Imaging Radiometer with Aperture Synthesis (MIRAS)

22. The first SMOS Global Soil Moisture Map (20-23 June 2010)
P. Richaume, CESBIO 22

23. VALIDATION OF GEOPHYSICAL DATA PRODUCTS: OCEAN SALINITY
SMOS sea surface salinity versus in-situ observations for April to October 2010
Statistics of differences “quasi global” for lLatitudel≤55°
Global SMOS error: 0.4 psu !
Level 2 ocean salinity data products released to the science community in Oct 2010
Progress has been made in responding to the mission objectives
Presently the global SMOS error has reached psu and for subareas even less (0.3 psu for Tropical Pacific Ocean)
Areas for improvements
RFI contamination in particular for lLatitudel≥55°
Long-term drift
Land-sea contamination
In-situ measurements: ARGO + buoys
Match-ups SMOS with in situ: distance <50 km & time lag < 12 hours
SMOS L2 SSS too salty in the mean by ~0.16 psu
© IFREMER (Reul et al. 2011)

24. GODAE Ocean View: Key Issues for ESA
Ocean Forecasting and data assimilation of is of strategic importance to ESA (satellite development, climate monitoring, GMES…)
Integration of models and observations is the key to a successful monitoring programme
Observation operators & data assimilation techniques are essential to improve models’ performance and confidence in results
Model re-analyses offer the potential to provide high quality datasets that are also methodologically consistent
Assist & inform the design of optimal observational systems via Observation System Simulation Experiments (OSSEs)
Monitoring programmes should inform future model developments
Document title | Author Name | Place | Data doc | Programme | Pag. 24

25. In summary: ESA produces Global Ocean Products
Salinity
Geoid
Dynamic Topography
Geostrophic Ocean Currents
Level 4 - Global composite products produced regularly from Envisat data today are an indication of how far we have come with obtaining data sets that are relevant to studies of ocean circulation and ocean biology. This synergy helps understand the role of ocean dynamics in ocean productivity, and together with wind and sea-state information will help contribute to understanding the biological pump and draw down of CO2 in the ocean.
Ocean Colour
Sea Surface Temperature

26. And: The Challenge remains to exploit Synergy and Mesoscale Processes
Ocean colour
SST
The power of collocated products is indicated by this series of panels. This is a location off South Africa, in the Agulhas Current. One sees distinctly the warm water being transported by the current in the upper left. Instabilities and mesoscale eddies generated in the Agulhas retroflection are Captured in the SST, whilst the ocean colour data indicate where the productivity is taking place.
The SAR data in the lower left help to illustrate zones of convergence and divergence, corresponding to the large eddy and frontal zones, where the biology is concentrated. The SAR is used to generate high resolution wind products, indicated by the orange vectors, and the alongshore wind is reponsible for upwelling and the strong biological Activity observed along the coast. Additional complementary new products such as ‘sun glitter’ are also being generated from the optical data to understand the slope distribution at the ocean surface. Together these data provide a wealth of new information about mesoscale ocean processes.
MODIS Brightness temperature: with top two panels indicating SST and ocean colour retrievals
Bottom two panels indicate ASAR derived roughness and wind direction (?)
Sun glitter
Roughness

27. Summary
ESA has many ocean sensors and archive data that are world class: please continue to use of them for assimilation, validation and monitoring and feedback your experience, issues and problems/successes to ESA so that we can do better. (This is essential for further development etc)
As we move to coupled ocean-atmosphere systems EO ocean sensors and assimilation will be essential.  ESA look to GOV-ST to drive the use of EO data in ocean forecasting forwards.
International collaboration is essential and ESA has CCI, CEOS VC's etc amongst other mechanisms to help coordinate.  GOV-ST can help us demonstrate the usefulness of EO data so that we can continue to provide better capabilities.
Document title | Author Name | Place | Data doc | Programme | Pag. 27

28. THANK YOU