1_Buck - Wavemil Steps IGARSS-11.ppt

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  • Wavemill will try to address these limitations. It is an interferometric SAR altimeter with a wide swath that uses the doppler shift of the signal. It operates in the Ku band and the antennas are configured such that there is a cross track and along track separation. The four antennas are 4.5 m long and 0.35 m wide and use an interleaved slotted waveguide technology. The beams can be electronically steered as well. The phase centres are 12.4 m apart in the along track direction. The image here shows the location of the antennas. The antennas will be sequentially pulse. So antenna 1 will transmit and receive while antenna 3 receives. Then antenna 2 and so on and so on. This produces co-time and co-location interferograms.
  • So with the 4 squinted beams (the fore, aft and right, left) and 2 observations per beam (bi-static and mono static) a total of 8 interferograms are produced. The multiple observations in a single pass allow direct measurements of ocean surface motion in 2 dimensions and also the sea surface height. Independent self-calibration capabilities of interferometric baseline
  • 4 squinted beams Fore and aft Right and left 2 observations per beam Bi-static Mono-static 8 channels in total Multiple geophysical observations Direct measurement in two dimensions of ocean surface motion Two independent observations (fore, aft) of sea surface height Scatterometric data Independent self-calibration capabilities of interferometric baseline
  • 1_Buck - Wavemil Steps IGARSS-11.ppt

    1. 1. IGARSS 2011 Vancouver 29 July 2011 Christopher Buck , Miguel Aguirre, Craig Donlon, Daniele Petrolati, Salvatore D’Addio ESA/ESTEC STEPS TOWARDS THE PREPARATION OF A WAVEMILL MISSION
    2. 2. Wavemill Concept <ul><li>Wavemill is an RF instrument concept which uses hybrid (along- and across-track) interferometry for the direct measurement of 2D ocean surface currents </li></ul><ul><li>Potential additional applications include inland water: lake height, river flow rate and ice freeboard </li></ul><ul><li>The TRP funded feasibility study generated very promising results suggesting accuracies of better than 10cm/s and 5° for dual swaths of 100km to either side of the sub-satellite track </li></ul><ul><li>On-board processing is required to reduce the high data rate and a breadboard activity for this is reserved in the current TRP work plan </li></ul><ul><li>The antenna development is also in the TRP work plan </li></ul><ul><li>A demonstration campaign will take place in the autumn, funded by EOP </li></ul><ul><li>EOP is also funding a mission study (phase 0) which will capitalize on the findings of the scientific analysis to be covered in a soon to start GSP activity </li></ul>
    3. 3. Wavemill Concept <ul><li>The basis is a wide swath interferometric SAR instrument </li></ul><ul><li>Operating in K u band with a 100MHz bandwidth and a PRF of 2700Hz </li></ul><ul><li>The antenna configuration is such that there is a separation of the antennas in both the across- and along-track directions </li></ul><ul><li>2D current measurements and topography mapping will be possible in a single pass </li></ul><ul><li>The asymmetry of the viewing geometry permits some estimation of the baseline errors </li></ul>
    4. 4. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km t o 280 km 3 km Wavemill Operation
    5. 5. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km t o 280 km 3 km Wavemill Operation
    6. 6. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km t o 280 km 3 km Wavemill Operation
    7. 7. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km t o 280 km 3 km Wavemill Operation
    8. 8. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km 280 km 3 km Wavemill Operation
    9. 9. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km 280 km 3 km Wavemill Operation
    10. 10. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km 280 km 3 km Wavemill Operation
    11. 11. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km 280 km 3 km Wavemill Operation
    12. 12. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km 280 km 3 km Wavemill Operation
    13. 13. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km 280 km 3 km Wavemill Operation
    14. 14. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km 280 km 3 km Wavemill Operation
    15. 15. 100 km Sub-Satellite Track Flight Direction 90 km Orbit Height ~550 km 280 km 3 km Wavemill Operation
    16. 16. Wavemill System Parameters <ul><li>On-board (burst) SAR processing up to generation of multi-look interferograms </li></ul><ul><li>A total of 8 interferograms generated on board </li></ul><ul><li>Total computational power < 45 GOPS </li></ul><ul><li>Baseline calibration, phase separation & L2 products processed on ground </li></ul>
    17. 17. Scientific Requirements <ul><li>OCEAN SURFACE CURRENT REQUIREMENTS </li></ul>
    18. 18. Ocean Challenges <ul><li>To quantify the interaction between variability in ocean dynamics, thermo-haline circulation, sea level and climate </li></ul><ul><li>To understand physical and bio-chemical air/sea interaction processes </li></ul><ul><li>To understand internal waves and the ocean mesoscale, its relevance to heat and energy transport and its influence on primary productivity </li></ul><ul><li>To quantify marine eco-system variability, its natural and anthropogenic physical, biological and geochemical forcing </li></ul><ul><li>To understand land/ocean interaction in terms of natural and anthropogenic forcing </li></ul><ul><li>To provide both model- and data-based assessments and predictions of past, present and future states of the oceans </li></ul>
    19. 19. Cryosphere Challenges <ul><li>Quantify the distribution of sea-ice mass and freshwater equivalent, assess the sensitivity of sea-ice to climate change and understand thermodynamic and dynamic feedback [systems] to the ocean and atmosphere </li></ul><ul><li>Quantify the mass balance of grounded ice sheets, ice caps and glaciers, partition their relative contributions to global eustatic sea-level change and understand their future sensitivity to climate change through dynamic processes </li></ul><ul><li>[…] </li></ul><ul><li>Quantify the influence of ice shelves, high-latitude river run-off and land ice melt on global thermo-haline circulation, and understand the sensitivity of each of these freshwater sources to future climate change </li></ul><ul><li>[…] </li></ul>
    20. 20. Land Challenges <ul><li>Understand the role of terrestrial ecosystems and their interaction with other components of the Earth system for the exchange of water, carbon and energy, including the quantification of the ecological, atmospheric, chemical and anthropogenic processes that control these biochemical fluxes </li></ul><ul><li>[…] </li></ul><ul><li>Understand the pressure caused anthropogenic dynamics on land surfaces (use of natural resources, land use and land-cover change) and their impact on the functioning of terrestrial ecosystems </li></ul><ul><li>[…] </li></ul>
    21. 21. Scientific Objectives Land Challenges 1 and 3 P 9. Improve and validate hydrological models through data assimilation and improve freshwater inflow into the ocean. Ocean Challenges 1 and 5 P 8. Improve and validate numerical ocean circulation model and data-based assessment and prediction of ocean circulation Land Challenges 1 and 3 S 7. Quantify and map river flows and river flow variability Cryosphere Challenges 1, 2 and 4 S 6. Quantify and map the size, velocity and the variability of icebergs Cryosphere Challenges 1, 2 and 4 P 5. Quantify and map the variability of sea ice, sea ice thickness and velocity Ocean Challenges 1, 2, 3, 4 and 5 P 4. Quantify and map ocean swell and waves at regional and global scales Ocean Challenge 1 P 3. Evaluate and reduce the uncertainty of (sub)-mesoscale ocean surface current variability measurements at regional and global scales Ocean Challenges 1, 2, 3, 4 and 5 P 2. Quantify and map (sub)-mesoscale sea surface height and its variability Ocean Challenges 1, 2, 3, 4 and 5 P 1. Quantify and map (sub)-mesoscale (<0.1 – 10 km) ocean surface current vectors and their variability ESA’s Living Planet Programme Challenges Addressed Primary or Secondary Objective Wavemill Scientific Objectives
    22. 22. Feasibility Study <ul><li>TRP funded activity won by Starlab with Astrium and IFREMER </li></ul><ul><li>KO Jan 2008 tasks were: </li></ul><ul><ul><li>Determination of Scientific Requirements </li></ul></ul><ul><ul><li>System Analysis </li></ul></ul><ul><ul><li>Instrument Design </li></ul></ul><ul><li>Results were encouraging, CCN initiated to investigate ‘javelin’ concept using ‘leaky wave’ antennas </li></ul><ul><ul><li>Completed July 2010 </li></ul></ul><ul><li>Outcome of completed study plus CCN: </li></ul><ul><ul><li>Basic scientific requirements for ocean currents </li></ul></ul><ul><ul><li>First cut instrument and spacecraft designs </li></ul></ul>
    23. 23. Proof of Concept Campaign <ul><li>EOEP funded activity </li></ul><ul><li>KO 9 May 2011 </li></ul><ul><li>Tasks: </li></ul><ul><ul><li>Prepare existing airborne interferometric SAR system for Wavemill operation (squinted beams preferably fore and aft) </li></ul></ul><ul><ul><li>Fly campaign over region with ground truth (HF radar, ADCPs, bathymetry) </li></ul></ul><ul><ul><li>Campaign flights over Liverpool Bay end September/beginning October 2011 </li></ul></ul><ul><ul><li>Process hybrid and co-time data, extract surface currents </li></ul></ul><ul><ul><li>Compare and validate results/instrument/processing and provide recommendations for spaceborne instrument </li></ul></ul><ul><ul><li>Workshop - release data to scientific community </li></ul></ul>
    24. 24. End-to-end Simulator <ul><li>Development by Starlab (E) due to accrued know-how and proven competence in the development of relevant simulators (GNSS-R and WSOA) </li></ul><ul><li>Structure: </li></ul><ul><ul><li>Instrument model with configurable parameters (baselines, bandwidths, squint and look angles etc) </li></ul></ul><ul><ul><li>Sea surface state model (SWH, wind direction and strength, swell, fetch etc) </li></ul></ul><ul><ul><li>Processing (hybrid, co-time, interferogram generation, flattening etc) </li></ul></ul><ul><li>KO 5 July 2011, duration 18 months </li></ul>
    25. 25. Product Assessment Study <ul><li>GSP activity to be initiated Q3 2011 </li></ul><ul><li>Tasks: </li></ul><ul><ul><li>Review of Along-Track Interferometry – capability of ATI for current measurement, existing models, impact of wind and mitigation thereof </li></ul></ul><ul><ul><li>Validity of Scientific Products from a Wavemill Instrument </li></ul></ul><ul><ul><li>Scatterometry – extracting wind speed from Wavemill amplitude data </li></ul></ul><ul><ul><li>Additional Products – sea-ice, inland water/rivers </li></ul></ul><ul><ul><li>Synergy with other Instrument Data (e.g. conventional altimeter, thermal imager etc) </li></ul></ul>
    26. 26. Mission Requirements PoC Campaign Product Assessment Study Simulator Feasibility Study MRD System Study
    27. 27. Risk Retirement Activities <ul><li>In current TRP/GSTP plan: </li></ul><ul><li>Antenna breadboard </li></ul><ul><ul><li>“ Leaky wave” design – naturally squinted beams </li></ul></ul><ul><li>On-board processing breadboard activity to cover the full on-board processing steps for Wavemill including: </li></ul><ul><ul><li>SAR processing </li></ul></ul><ul><ul><li>Image registration </li></ul></ul><ul><ul><li>Co-time interferogram generation </li></ul></ul><ul><ul><li>Multi-looking </li></ul></ul><ul><ul><li>Flat earth correction </li></ul></ul><ul><ul><li>Hybrid interferogram generation </li></ul></ul><ul><ul><li>Hybrid phase separation </li></ul></ul><ul><li>Based on FFT and processing chipsets (e.g. PowerFFT, Leon II) </li></ul>
    28. 28. Wavemill Instrument <ul><li>2 in-line antenna structures </li></ul><ul><li>Fore and aft beam footprints </li></ul><ul><li>Broadside orientated to sub-sat. track </li></ul><ul><li>Leaky-wave array concept </li></ul>
    29. 29. Planning
    30. 30. More on Wavemill <ul><li>Advanced RF Sensors and Instruments Workshop, ESA/ESTEC. 12-15 September 2011 </li></ul><ul><li>Discussion group set up on LinkedIn – ‘Wavemill’ </li></ul><ul><li>Wavemill Science Workshop – December 2011/January 2012 at ESTEC </li></ul><ul><li>IGARSS 2012, Munich </li></ul>
    31. 31. Wavemill Thank you for your attention!

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