Sentinel-3 orbit determination at the copernicus pod service

Jaime Fernández (GMV, Spain)

CoAuthors

Peter Heike (PosiTim, Germany); Fernández Carlos (GMV, Spain); Pierre Féménias (ESA/ESRIN, Italy); Sylvie Labroue (CLS, France); Annabelle Ollivier (CLS, France)

Event: 2016 Ocean Surface Topography Science Team Meeting

Session: Precision Orbit Determination

Presentation type: Type Oral

The Copernicus POD (Precise Orbit Determination) Service is part of the Copernicus PDGS Ground Segment of the Sentinel missions. A GMV-led consortium is operating the Copernicus POD (CPOD) Service being in charge of generating precise orbital products and auxiliary data files for their use as part of the processing chains of the respective Sentinel PDGS.
Sentinel-3 is the third mission of the Copernicus program. The orbit accuracy requirement is very stringent with 2-3 cm in radial direction mainly because of the radar altimetry observations. In addition to the SAR radar altimeter the Sentinel-3 satellites carry as main payloads an Ocean and Land Colour Instrument (OLCI), a Microwave Radiometer, and a Sea and Land Surface Temperature Radiometer (SLSTR). The Sentinel-3 mission thus assures continuity of ERS, ENVISAT and SPOT vegetation data.
The POD instruments are a GPS receiver, a DORIS receiver and a Laser Retro Reflector for Satellite Laser Ranging (SLR) to the satellite. On the one hand, the three different techniques GPS, SLR and DORIS make POD more complex but, on the other hand, it is very helpful to have independent techniques available for validation of the orbit results. The three techniques are, therefore, equally important to fulfil the orbit accuracy requirements. The CPOD Service processes GPS and SLR data routinely and has the capacity to process DORIS in Non-time Critical (NTC) and reprocessing campaigns.
Three different orbit products are provided for Sentinel-3. A Near Real Time (NRT) product (latency: 30 minutes; radial orbit accuracy requirement: 8-10 cm), a Short Time Critical (STC) product (1.5 days; 3-4 cm) and an NTC product (28 days, 2-3 cm). The NRT processing has been developed by the Copernicus POD Service but it is running externally at the PDGS Marine Centre (EUMETSAT) and at the Core Ground Station (Svalbard). The STC and NTC processing is running at GMV. The orbit predictions needed for successful SLR tracking are provided by the CPOD Service as well.
The first satellite of the mission Sentinel-3A was launched on 16 February 2016. The POD processing has been fine-tuned during the five months of commissioning phase. The accumulated experience from the already operational satellites Sentinel-1A and Sentinel-2A and a sophisticated testing before the launch of Sentinel-3A facilitated the procedures.
The CPOD Service is supported by the Copernicus POD Quality Working Group (QWG), which consists of several experts for POD of low Earth Orbiting satellites. Independent orbit solutions delivered by this group are used to validate the CPOD results and the recommendations from this body guarantee that the CPOD Service is updated following state-of-the-art algorithms, models and conventions.
The status of the POD processes for Sentinel-3A at the CPOD Service will be presented. Results from the commissioning and operational phase are shown. Cross-comparisons among different Sentinel-3A orbit solutions provided by the Copernicus POD QWG are presented. Orbit validation results based on SLR measurements and comparisons to DORIS-derived orbits will show the performance of all three POD instruments. In addition a fully independent validation of the orbit products based on Sea Surface Height Estimation is done by the Sentinel-3 Mission Performance Center.
 

Oral presentation show times:

RoomStart DateEnd Date
Auditorium Wed, Nov 02 2016,09:05 Wed, Nov 02 2016,09:20
Jaime Fernández
GMV
Spain
jfernandez@gmv.com