ACCRA : A Study on Future Microwave Radiometers for Atmospheric Correction of Radar Altimeters on Coastal Regions

Bruno Picard (CLS, France)

CoAuthors

Janet Charlton (JCR System, U.K.); Laura Hermozo (CLS, FRANCE); Laurence Eymard (LOCEAN/IPSL, FRANCE); Fatima Karbou (CNRM/GAME, France); Adrian R.L. Tatnall (SOTON, U.K.); Brian Monya (STFC, U.K.); Soe M. Tun (SMT, U.K.); Manuel Martin-Neira (ESA/ESTEC, Netherland)

Event: 2016 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Corrections

Presentation type: Type Oral

The wet tropospheric correction (WTC) is a major source of uncertainty in altimetry budget error, due to its large spatial and temporal variability: this is why the main altimetry missions include a microwave radiometer (MR) The commonly agreed requirement on WTC for current missions is to retrieve WTC with an error better than 1cm rms.

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 are anticipated for coastal and inland waters. Nevertheless, the quality of data in those areas are expected to be degraded with respect to those of the open oceans due to the rather wide field of view of the MR (-3 dB beam-width of ~20 km). As a matter of fact, the MR observations over those waters are subject to contamination by land brightness temperatures which fall within the MR footprint.

The present team has been selected by ESA/ESTEC to work on a MR instrument design for future operational radar altimetry missions. Such a design shall include the classical MR channels for ensuring observation continuity, augmented by a set of high frequency channels for enabling accurate altimetry over coastal and inland waters.

In this study team, the extensive systems and radiometric engineering experience of JCR Systems is complemented by a significant expertise of LOCEAN , CLS and CNRM in water vapour retrievals, a considerable experience in design and development of microwave and millimeter wave radiometer front ends from RAL and a substantial knowledge of SMT Consultancies in microwave and millimeter-wave antenna design.

We will present the final results of this study.

First, the selection of an optimal set of observation frequencies based on an analysis of both potential horizontal resolution and the value of the physical information provided.

Then, the instrument design selected in consistency with the selected channels.

And finally, the results of a dedicated 1D-VAR retrieval approach with a specific strategy over coastal areas, using the best of each observation frequency.

These results using the ACCRA configuration are discussed against the configuration of Jason-CS.
 

Oral presentation show times:

RoomStart DateEnd Date
Auditorium Tue, Nov 01 2016,14:30 Tue, Nov 01 2016,14:45
Bruno Picard
CLS
France
bpicard@cls.fr