Key Laboratory of Microwave Remote Sensing Chinese Academy of Sciences (MiRS, CAS) National Space Science Center Chinese Academy of Sciences IGARSS 2012, Munich, Germany July 22-27, 2012 PROGRESSES OF DEVELOPMENT OF CFOSAT SCATTEROMETER Xiaolong Dong , Di Zhu CAS Key Laboratory of Microwave Remote Sensing National Space Science Center, CAS PO Box 8701, Beijing, China [email protected], [email protected]
Progresses of development of cfosat scatterometer. Xiaolong Dong , Di Zhu CAS Key Laboratory of Microwave Remote Sensing National Space Science Center, CAS PO Box 8701, Beijing, China [email protected] , [email protected]. Outline of the Presentation. Introduction to the Mission - PowerPoint PPT Presentation
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Key Laboratory of Microwave Remote SensingChinese Academy of Sciences
(MiRS, CAS)
National Space Science CenterChinese Academy of Sciences
IGARSS 2012, Munich, GermanyJuly 22-27, 2012
PROGRESSES OF DEVELOPMENT OF CFOSAT SCATTEROMETER
Xiaolong Dong, Di ZhuCAS Key Laboratory of Microwave Remote Sensing
National Space Science Center, CASPO Box 8701, Beijing, China
Key Laboratory of Microwave Remote SensingChinese Academy of Sciences
(MiRS, CAS)
National Space Science CenterChinese Academy of Sciences
IGARSS 2012, Munich, GermanyJuly 22-27, 2012
Outline of the Presentation
• Introduction to the Mission• Specifications of SCAT• Description of SCAT system• Simulation of SCAT system
performances• Progresses• Summary
Key Laboratory of Microwave Remote SensingChinese Academy of Sciences
(MiRS, CAS)
National Space Science CenterChinese Academy of Sciences
IGARSS 2012, Munich, GermanyJuly 22-27, 2012
CFOSAT Mission
• CFOSAT: Chinese French Oceanography SATellie
• Launch plan: 2014• Mission Objectives: monitoring the wind and waves at the ocean
surface at the global scale in order to improve:– The wind and wave forecast for marine
meteorology (including severe events)– the ocean dynamics modeling and
prediction,– our knowledge of climate variability– fundamental knowledge on surface
processes linked to wind and waves
• Two payloads:– SWIM (Sea Wave Investigation and
Monitoring by satellite)• A Ku-band real aperture radar for
measurement of directional ocean wave spectra;
– SCAT (SCATterometer)• A Ku-band rotating fan-beam radar
scatterometer for measurement of ocean surface wind vector.
Key Laboratory of Microwave Remote SensingChinese Academy of Sciences
(MiRS, CAS)
National Space Science CenterChinese Academy of Sciences
IGARSS 2012, Munich, GermanyJuly 22-27, 2012 4
Mission-measurement requirements• Joint measurement of ocean surface wind vector
and sea-state parameters from radar – Both wind vector and wave parameters can be measured using active micro-wave
remote sensing (heritage of altimeter, sactterometer and SAR missions, and airborne radar measurements)
– Wind vector => optimal configuration at medium incidence angle (20-50°)– Wave spectra => optimal configuration at low incidence angle (< 15°)
• CFOSAT mission with two payloads– SWIM: wave scatterometer: multi-beam Ku-Band radar at low incidence – SCAT: wind scatteromer: Fan beam Ku-Band radar at medium incidence
4
Key Laboratory of Microwave Remote SensingChinese Academy of Sciences
(MiRS, CAS)
National Space Science CenterChinese Academy of Sciences
IGARSS 2012, Munich, GermanyJuly 22-27, 2012
Mission-Wind Vector Payload -SCAT• A Ku-band rotating fan-beam radar
scatterometer (Ku-RFSCAT) for sea surface wind vector retrieval by measurement of the sea surface backscattering coefficient.
• Adapted to the platform constraints (small size);
• 2 fan beams (HH & VV) cover incident angles from 26 degree to 46 degree from nadir
• scanned with a rotation speed of around 3.5 rpm.
• For each of the ground resolution cells, more than four looking angles can be obtained to retrieval wind vector information.
5
Rotating fan-beam antenna
Nadir Point
Flight direction
Swathfootprint
Key Laboratory of Microwave Remote SensingChinese Academy of Sciences
(MiRS, CAS)
National Space Science CenterChinese Academy of Sciences
IGARSS 2012, Munich, GermanyJuly 22-27, 2012
Characteristics of CFOSAT SCAT
• Wide swath by rotating of beam;– Decided by outer edge of incident angle of beam
• More number of azimuth look angles by overlap of beam;– Decided by flying speed, rotating speed and beamwidth
• NRCS/sigma 0 dependent on antenna beam;– Decided by local antenna gain along elevation
• Single antenna for all azimuth directions;– No inter-beam balance required– But azimuth fluctuation may exist due to rotating
mechanism
Key Laboratory of Microwave Remote SensingChinese Academy of Sciences
(MiRS, CAS)
National Space Science CenterChinese Academy of Sciences
IGARSS 2012, Munich, GermanyJuly 22-27, 2012
Azimuth look angle combinations for surface resolution cells
Track of nadir porints
Surface resolution cell 2
Surface resolution cell 1
Overlap between adjacent scannsfor large number of azimuth view for each pixel. Dual polarization is used to improve retrieval of outer and center part of the swath
Key Laboratory of Microwave Remote SensingChinese Academy of Sciences
(MiRS, CAS)
National Space Science CenterChinese Academy of Sciences
IGARSS 2012, Munich, GermanyJuly 22-27, 2012
Specifications for SCAT
• Objectives:– Measurement of global surface sigma 0– Retrieval of global ocean surface wind vector
• Data requirements– Swath width: >1000km– Surface resolution: 50km (standard); 25km (goal)– Data quality (at 50km resolution)– s° precision:
• 1.0dB for wind speed 4~6m/s• 0.5dB for wind speed 6~24m/s
– Wind speed: 2m/s or 10% @ 4~25m/s– Wind direction: 20deg @ 360deg for most part of the swath
• Life time: 3yrs
Key Laboratory of Microwave Remote SensingChinese Academy of Sciences
(MiRS, CAS)
National Space Science CenterChinese Academy of Sciences