Mobile version

CFOSat

Image of the Month - March 2020

Waves are a key issue for marine services, maritime commerce and coastal urbanization. Understanding and forecasting sea state during storms or hurricanes is a safety issue. Up to end of 2018, two types of satellites were measuring waves. First, the Synthetic Aperture Radars estimate directional waves spectra from the  sea surface roughness measurements, but they are limited to long waves. Secondly, the radar altimeters are measuring "only" the significant wave heights at nadir over the whole ocean.
CFOSAT is a French-Chinese satellite launched on October 29, 2018. It carries a wind scatterometer (SCAT) developed by CNSA, but also a brand-new instrument measuring waves (SWIM , a wave scatterometer), developed by CNES. This instrument measures directional wave spectra , i.e. the wave energy as a function of direction and frequency. 
SWIM operates in Ku-band (13.575 GHz), frequently used in nadir altimetry. It is a real aperture radar which illuminates the surface sequentially through six beams with six incidence angles: 0°, 2°, 4°, 6°, 8° and 10°. The beams feed horns are mounted on a rotating antenna allowing the scanning of the whole azimuth angles.
The signal backscatter is analyzed for all the emission directions of the rotation, and thus provides wave directional spectra after aggregating the data measured during a complete rotation. The nadir beam operates like a classical altimeter. However, it provides only significant wave height and wind-speed information, sea-surface height cannot be provided (no precise orbit determination, no radiometer). The signal measured by off-nadir beams depends on wave's slope and sea states. It will improve the characterization of  ocean processes and the modeling of ocean/atmosphere coupling.
The presence of this wave scatterometer and of a wind scatterometer enables co-located measurements of two essential parameters for marine weather and sea state knowledge for the very first time. 
With such information, the marine weather forecasts and the coastal warning (e.g. storm surges) will be improved. CFOSAT has now finished its validation phase, and the data are available for research and pre-operational applications.

See also:

Other web sites on this topic:

References:

  • Hauser D., Tourain C., Hermozo L. Alraddawi D., Aouf L., Chapron B., Dalphinet A., Delaye L., Gressani V., Grouazel A., Guitton G., Husson R., Mironov A., Mouche A., Ollivier A., Oruba L., Piras F., Rodriguez Suquet R., Schippers P., Tison C., 2019: New observations from the SWIM radar on board CFOSAT : instrument validation and ocean wave measurement assessment", submitted to IEEE Trans on Geoscience and Remote Sensing
  • Tourain C., F. Piras, A. Olivier, P. Thibaut, F. Boy, JC Poisson, L. Hermozo, D. Hauser, C. Tison, 2019: CFOSAT SWIM  adaptiveretracking: description and validation”, submitted to IEEE Trans on Geoscience and Remote Sensing
  • Hauser, D. , L. Aouf, B. Chapron, F. Collard, A. Dalphinet, L. Delaye, C. Dufour, F. Gouillon, A. Grouazel, G. Guitton, L. Hermozo, J.-M. Lachiver, A. Mironov, A. Mouche, F. Nouguier, A. Ollivier, R. Rodriguez, P. Schippers, C. Tison, C. Tourain 2019: CFOSAT: New wind and wave observations from the nadir and near-nadir SWIM Ku-Band instrument, Ocean Surface Topography Science Team Meeting, Chicago, Oct. 2019.

 

 

EnglishFrançais
Rss feedsContactPartnersFAQLexiconLegal noticePersonal Data Protection PolicyMobile
You must enable cookies in your browser preferences to save the modifications
You are using an older version of Internet Explorer, please update to take full advantage of Aviso+ features

Customize the home page

View all widgets
Reduce display
Public profile
User profile

Select/Deselect widgets

Discover AVISO+

Customizable home, reading tools, products search guide, etc.. Discover step by step the features of the new site AVISO+.

Customizable homepage

This home page is composed of blocks called "widgets".

Rearrange the blocks with a "Click & Drop".

Hide a widget with the cross at the top right. Reset or add a widget with the "wrench" icon. The "User" and "Public" profiles offer a predefined organization.

All the modifications are automatically saved as cookies on your machine so as to enable you to have your own specific AVISO+.

Reading tools

Ease your reading by choosing the page background colour (black/white) and/or by modifying the font size.

Browsing menu and breadcrum trail

To ease your browsing through AVISO+, you can use at any time the main banner items with the interactive submenus or use the browsing menu on the left side of the screen (it is open by default). For more readiness of the page contents, you can fold and unfold the browsing menu by clicking on the tab. At any time you can know where you are thanks to the browsing menu or the breadcrum at the top of the page.

Products search guide

The first submenu of the "Data" banner item leads you to a new search form enabling you to find quickier the product that suits your needs. The list of results is updated according to your selection criteria.

AVISO+ Multimedia

The first submenu of the "Multimedia" banner item leads you to AVISO+ collections of images and videos linked to altimetry and its applications. Have a nice visit!