Speaker
Description
The wet tropospheric correction (WTC) is a major source of uncertainty in a radar altimetry budget error, due to its large spatial and temporal variability: this is why the most altimetry missions include a microwave radiometer. With the introduction of the along-track synthetic aperture processing, first implemented in CryoSat-2, and now in the upcoming operational altimetry missions such as Sentinel-3 and Jason-CS, more accurate altimetry data is anticipated for coastal and inland waters. Yet the WTC in coastal areas is degraded with respect to that of the open oceans due to the wide field of view of the current microwave radiometers which are also subject to contamination by land brightness temperatures which fall within the radiometer footprint.
The objective of this study was to build upon an earlier TRP study, to design a multi-frequency radiometer antenna and feed system that could provide such accurate atmospheric corrections. In order to meet this objective the study was divided into four major tasks. Each task generated a Task Report, a summary of which can be found in the Final Report.
Task 1 completed a review of relevant state of the art technologies for antenna concepts operating in multiple frequency bands. Mission characteristics and radiometer instrument requirements were critically reviewed and a preliminary requirements specification for the radiometer antenna derived.
Task 2 established a wide range of antenna configurations utilising the most promising of the identified technologies. Each antenna concept was assessed for critical performance and accommodation factors and traded off to identify a preferred configuration.
Task 3 undertook detailed RF design and analysis of the selected antenna architecture. This included a preliminary evaluation of a typical thermal and structural environment and the associated thermo-elastic deformation of the antenna on the overall performance.
Task 4 provided a development plan and a technology roadmap for the critical elements of the radiometer antenna including verification requirements. Recommendations included a number of areas for further study including further definition of user requirements as well as further refinement of the thermal design for non sun synchronous mission. Technical Development Programmes were also proposed that covered components as well as development of on-ground verification techniques for large aperture radiometers.
| ESA Technical Officer | Maurice Paquay- ESA Technical Officer |
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