Sentinel-3 Transponder Calibration Results

Albert Garcia-Mondejar (isardSAT, Spain)

CoAuthors

Stelios Mertikas (Space Geomatica PC , Greece); Demitris Galanakis (Space Geomatica PC, Greece); Sylvie Labroue (CLS, France); Jerome Bruniquel (ACRI-ST, France); Graham Quartly (Plymouth Marine Laboratory, United Kingdom); Pierre Féménias (ESRIN/ESA, Italy); Constantin Mavrocordatos (ESTEC/ESA, The Netherlands); Pablo Garcia (isardSAT, Spain); Mònica Roca (isardSAT, Spain)

Event: 2017 Ocean Surface Topography Science Team Meeting

Session: Regional and Global CAL/VAL for Assembling a Climate Data Record

Presentation type: Type Poster

Sentinel-3 is the Earth observation satellite mission designed to ensure the long-term collection and operational delivery of high-quality measurements of, among others, the sea surface topography. Post-launch calibration and validation of the satellite measurements is a prerequisite to achieve the desired level of accuracy and ensure the return of the investment. These Calibration/Validation (Cal/Val) services are provided by independent, external Cal/Val facilities that determine the error in satellite measurements, using known and controlled signal inputs on the ground. Sentinel-3 altimeter calibration site was established in West Crete, Greece. This site has been named CDN1 Cal/Val site and is located at an elevation of 1050m on the western mountains of Crete.

Transponders are commonly used to calibrate absolute range from conventional altimeter waveforms because of their characteristic point target radar reflection (not in the case of regenerative transponders). The waveforms corresponding to the transponder distinguish themselves from the other waveforms resulting from natural targets, in power and shape.

The transponder is used to calibrate SRAL’s range and datation to meet the mission requirements. For this calibration, the S3 L1A data is processed with a specialised transponder processor. Atmospheric delays are acquired directly from the calibration site providing better accuracy to the final range measurement. Ideally, the comparison between the theoretical values provided by the well-known target, and the measurement by the instrument to be calibrated provides us with the error that the instrument is introducing when performing its measurement. When this error can be assumed to be constant regardless the conditions, it will provide the bias of the instrument. If the measurements can be repeated after a certain period of time, it can also provide an indication of the instrument drift.

This poster presents the range and datation results using the Crete transponder for the first 22 cycles. This work is been carried out within the Sentinel-3 Mission Performance Center activity S3MPC.
 

Poster show times:

RoomStart DateEnd Date
Concerto Ballroom Thu, Oct 26 2017,14:00 Thu, Oct 26 2017,18:00
Albert Garcia-Mondejar
isardSAT
Spain
albert.garcia@isardsat.cat