SWIM NRT products with a focus on the nadir beam processing

Cédric Tourain (CNES, France)


Céline Tison (CNES, France); Thomas Grelier (CNES, France); Danièle Hauser (LATMOS, France); Patricia Schippers (LATMOS, France); Lauriane Delaye (ACRI, FRANCE); Arnaud Jouzeau (CNES, France)

Event: 2016 Ocean Surface Topography Science Team Meeting

Session: Application development for Operations

Presentation type: Type Oral

The SWIM (Surface Wave Instrument Monitoring) is a wave conical scanning scatterometer in Ku-band with 6 incidence angles (from 0° to 10°) which will be embarked on the CFOSAT mission [1]. CFOSAT is a Chinese-French oceanographic mission for the joint observation of the wave and the wind vectors at the oceanic surface. SWIM Near Real Time (NRT) products will help for marine and weather forecast and for climate monitoring. It will provide a very accurate description of the sea surface, which can greatly benefit to altimetry studies (e.g. modeling of electromagnetic bias).
The definition of the ground processing of the ground data is now well advanced. The SWIM NRT products are defined as follows:
The first level products consist in:
- L1A : calibrated and geocoded waveforms,
- L1B : modulation spectrum for beams 6 to 10° (spectrum beams)
Then the SWIM ground segment generates three types of information gathered in L2 product.
- The nadir estimates, significant wave height and wind speed are determined similarly to a conventional altimeter. In SWIM case, data processing will benefit from innovative algorithms that we will detail in the presentation (numerical retracking, ADAPTIVE model).
- The sigma0 average data, the six beams are used to get the backscattering coefficient profiles from 0 to 10° of incidence and for all azimuths.
- Finally for incidences from 6 to 10° the wave data provides a complete characterization of waves with two dimensions wave spectra, partitioning and geophysical parameters. This product will be a major asset to better understand the altimetry products (sea state bias, swell impact, etc.)
In order to validate on ground the processing and algorithms chosen, software prototypes have been developed by CNES and LATMOS for all level products from L1 to L2. They have been applied on simulated data from the SWIM simulator, SimuSWIM [2], the surfaces being generated from the outputs of the wave models WAM (ECMWF) or MF-WAM (Météo France)
This presentation will describe the SWIM NRT products, the main data processing principles considered for the different levels and the expected results, based on simulation results. A specific focus will be done on the nadir beam.
[1] Hauser D., C. Tison, J.-M. Lefevre, J. Lambin, T.Amiot, L. Aouf, F. Collard, and P. Castillan, Measuring ocean waves from space: Objectives and characteristics of the China-France Oceanography SATellite (CFOSAT), Proceedings of the ASME 2010 29th International Conference on Ocean, Offshore and Arctic engineering, 2010
[2] Tison C., Amiot T., Enjolras V., Hauser D., Rey L., Souyris J.C., Castillan P., Performance status of the wave scatterometer SWIM, IGARSS'10, 2010

Oral presentation show times:

RoomStart DateEnd Date
Richelieu Wed, Nov 02 2016,09:45 Wed, Nov 02 2016,10:00
Cédric Tourain