WAVEMILL PRODUCT ASSESSMENT – DEFINING PRODUCTS AND EVALUATING POTENTIAL PERFORMANCE FROM A NOVEL SPACEBORNE INTERFEROMETRIC SAR

摘要

ocean properties for oceanographers and operators inthe maritime domain. Improved monitoring of oceancurrents is systematically the number one requirementthat emerges from any science or end user requirementsurveys.Wavemill is a novel hybrid interferometric SAR systemfirst proposed by ESA/ESTEC [Buck, 2005]. It offersthe possibility of generating two-dimensional wideswath, high resolution, high precision maps of surfacecurrent vectors and ocean topography [Buck et al.,2009]. Based on a single spacecraft, it avoids thedifficulties of synchronisation and baseline estimationassociated with other interferometric SAR systemsbased on two or more satellites (e.g. the “cartwheel” or“helix” concept).The Wavemill concept has developed steadily since itsfirst inception in 2005. A number of Wavemill studiesin recent years have gradually put together facts andfigures to support the case for Wavemill as a possiblespace-borne mission.The Wavemill Product Assessment study (WaPA)aimed to define the scientific capabilities and limitationsof a spaceborne Wavemill instrument in preparation fora possible submission of the Wavemill concept as acandidate Earth Explorer Core mission. The WaPAproject team brought together expert scientists andengineers in the field of SAR imaging of ocean currents,and included the National Oceanography Centre (UK),Starlab (Spain), IFREMER (France) and AirbusDefence and Space (UK). Overall project managementwas provided by Satellite Oceanographic Consultants(UK). The approach taken included:1. A review of SAR imaging of ocean currents inalong-track interferometric mode to learn fromprevious experiments and modelling what keyphenomena need to be accounted for to determinethe true performance of a spaceborne Wavemillsystem2. Validation of proposed Wavemill primary productsbased on Wavemill airborne proof-of-concept dataand numerical simulations to determine thecapabilities and limitations of a spaceborneWavemill instrument for ocean current vector andsea surface height mapping.3. An analysis of the potential for ocean wind vectorretrieval from a spaceborne Wavemill instrument.4. An investigation of possible secondary productsfrom Wavemill relating to rivers, ocean/atmosphereinteractions, ocean swell and cryosphericapplications.An assessment of the synergy between Wavemill andocean surface current products derived from otherremote sensing techniques, accounting for the natureand variability of the measured properties, to identifyany additional requirements on a future Wavemillmission.