The Role of the Sentinel-3 Mission Performance Centre in Maintaining High Standards within Operational Altimetry

Graham Quartly (Plymouth Marine Laboratory, United Kingdom)

CoAuthors

Sylvie Labroue (CLS, France); Marie-Laure Frery (CLS, France); Andrew Shepherd (University of Leeds, UK); Steve Baker (MSSL, UK); Alan Muir (MSSL, UK); Mònica Roca (isardSAT, Spain); Jean-Francois Cretaux (LEGOS, France); Frédérique Remy (LEGOS, France); Benoit Meyssignac (LEGOS, France); Saleh Abdalla (ECMWF, UK); Stéphane Calmant (IRD, France); Mathilde Cancet (Noveltis, France); Guillaume Valladeau (CLS, France); Pierre Féménias (ESA, Italy)

Event: 2015 Ocean Surface Topography Science Team Meeting

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

Presentation type: Type Poster

The series of Sentinel satellites mark a major step forward in the collection
of Earth Observation data with the commitment to a series of spacecraft and
sensors to construct long time series of data suitable for both climate
applications and widespread operational use. Amongst its many sensors,
Sentinel-3 will carry a delay Doppler altimeter, providing global
high-resolution data for the first time. The Sentinel-3 Mission Performance
Centre (S3-MPC) has been charged with ensuring the usefulness of such data by
performing quality control checks on the data (near real-time and offline
products), assessing the long-term performance through a series of ongoing
validation experiments. Although different processing centres will produce
the "marine" and the "terrestrial" data, the S3-MPC will be responsible for
the quality control (QC) and validation across all surfaces (ocean,
cryosphere and inland waters). The other tasks of the MPC deal with the
calibration of the altimeter (SRAL) and the microwave radiometer (MWR)
sensors but also with the validation of the algorithms in the ground
processing from Level 0 up to Level 2.

The MPC calibration component will include monitoring of SRAL instrument
performance, such as the Ultra Stable Oscillator (USO) and any changes in the
Point Target Response (PTR). Absolute calibration of SRAL range bias and
datation bias will be achieved by use of a purpose-built transponder in Crete.

The on-board microwave radiometer MWR will also be monitored during the
lifetime of the satellite to detect any possible anomaly or drift of the
instrument. The first months of the mission will be dedicated to the
calibration of the MWR and of the retrieval algorithms that provide all the
geophysical parameters relevant for the mission (wet tropospheric correction,
atmospheric attenuations etc…).

The validation component will address the needs and concerns of the different
altimetric communities. The performance over ocean will be assessed at global
scale, using cross calibration with other flying altimeters. The sea surface
height data will be also compared to local measurements at dedicated sites
such as Lake Issyk-kul and to the southwest of Corsica, as has been done
previously for Jason-1, Jason-2 and Envisat, whereas the information on
currents derived from the SSH gradient will be assessed relative to coastal
HF radar data in the southwest of England.. The oceanic records of wind speed
and wave height will be compared to buoy data and output from the ECMWF
model. The delay Doppler altimeter should enable better performances in
coastal waters or over inland waters (lakes and rivers) as it uses a much
smaller instrument footprint than conventional low-rate mode altimeters. The
S3-MPC will make a particular effort to evaluate the operation of the
on-board algorithms and ground processing for dealing with such relatively
small expanses of water. There will also be dedicated effort to validate the
quality of the altimeter information over ice sheets, by comparing data over
the Arctic sea-ice with measurements made within the IceBridge programme.

 

Poster show times:

RoomStart DateEnd Date
Grand Ballroom Foyer Thu, Oct 22 2015,11:00 Thu, Oct 22 2015,18:00
Graham Quartly
Plymouth Marine Laboratory
United Kingdom
gqu@pml.ac.uk