Sentinel-3A USO observed through GNSS measurements

Eva Jalabert (CNES, France)

CoAuthors

Flavien Mercier (CNES, France)

Event: 2016 IDS Workshop

Session: Precise Orbit Determination and clock

Presentation type: Type Oral

Sentinel-3A, an ESA altimetry mission, has been launched earlier this year (February 16, 2016). In order to precisely compute its orbit, a DORIS instrument and a GNSS receiver are embedded. The DORIS technique relies on the precise knowledge of a clock, given by an Ultra Stable Oscillator (USO).

As a low Earth orbiter, Sentinel-3A passes through the South Atlantic Anomaly (SAA), a region above the Earth surface where the energetic particles number is higher than usual, resulting in a higher level of radiation. The DORIS USO performances is degraded when passing through SAA, although the degradation varies depending on the mission considered (Spot5 and Jason 1 are particularly concerned by SAA degradation).
While SAA degradation is not obvious on Sentinel-3A when studying global metrics (RMS residuals over a cycle, …), a close up on the few DORIS passes over SAA shows that the DORIS USO is indeed perturbed.

A very interesting particularity of Sentinel-3A is that the same on-board oscillator is used by both the DORIS instrument and the GNSS receiver. Thus it is possible to estimate the clock using the GNSS measurements. This paper shows the results of using a GNSS-observed clock in the DORIS computation.

 

Oral presentation show times:

RoomStart DateEnd Date
Casoar Mon, Oct 31 2016,11:50 Mon, Oct 31 2016,12:10
Eva Jalabert
CNES
France
eva.jalabert@cnes.fr