TU3.T10.5.ppt

Estimation of wave spectra with SWIM on CFOSAT – illustration on a real case C. Tison (1 ) , C. Manent (2) , T. Amiot (1) , V. Enjolras (3) , D. Hauser (2) , L. Rey (3) , P. Castillan (1) (1) CNES, « Altimetry and Radar » department, France (2) UVSQ, CNRS, LATMOS-IPSL, France (3) Thalès Alenia Space, France [email_address]

Overview of the presentation ,[object Object],[object Object],[object Object],[object Object],[object Object]

The CFOSAT mission ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],More on the CFOSAT mission tomorrow – session WE4.T10 Altimetry I C hina F rance O ceanography SAT ellite

SWIM instrument (1/2) SWIM : S urface W ave I nvestigation and M onitoring Ku-band radar (scatterometer) 6 beams

SWIM instrument (2/2) Wind sea Swell ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Estimation of wave spectra Wave topography: ξ(x,y) Directional wave spectrum F(k x ,k y ) Modulation of the backscattering coefficient Signal modulation Modulation spectrum P m Received power Wave slopes Link slope/signal modulation

Simulations ,[object Object],[object Object],[object Object],[object Object],[object Object],End-to-end simulation tool: SimuSWIM 320 320 320 320 320 320 Bc (MHz) 2.3 4.8 6.8 8.7 11.9 24.3 SNR (dB) 237 192 144 60 60 110 Nimp (fixed) 6340-6667 variable 6378-6707 variable 6407-6739 variable 2125 fixed 2125 fixed 2125 fixed PRF (Hz) 37.4 30.1 22.5 31.5 31.5 51.8 Max integration time (ms) 10° 8° 6° 4° 2° 0°

Simulations ,[object Object],Input spectrum (models, measurements) Surface computation Backscattered signal (knowing SWIM geometry and properties) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],N imp pulses per cycles

Simulations ,[object Object],Input spectrum (models, measurements) Surface computation Backscattered signal (knowing SWIM geometry and properties) Estimated modulation spectrum Quality criteria

Impact of migrations (1/2) N imp N imp /2 NR ER MR FR Δ x MR ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Corrected by chirp scaling Non correctable ,[object Object],[object Object],[object Object]

Impact of migrations (2/2) (a) Reference 2D modulation spectrum (b) Estimated 2D modulation spectrum WITHOUT complete migration (c) Estimated 2D modulation spectrum WITH complete migrations Direction Wave- length Energy Swell 0° 0° 0% 3% 13% 10% Wind sea 11° 14° 27% 16% 19% 12%

A real sea state condition: “Prestige case” ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Spain Galician coast © BSAM/Douanes françaises

A real sea state condition: “Prestige case”

A real sea state condition: “Prestige case” ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Simulation results 06:00 UTC Reference: 2D spectrum from WAM model CFOSAT/SWIM estimation (simulations from SimuSWIM) ,[object Object],[object Object]

1D modulation spectra 6h UTC Swell Φ =135° (SE-NW look direction) Sea wind Φ = 235° (NE-SW look direction) Φ = angle between satellite track (assumed S-N) and radar look direction

00:00 UTC 06:00 UTC 08:00 UTC 15:00 UTC 10:00 UTC Reference: 2D spectrum from WAM model CFOSAT/SWIM estimation (simulations from SimuSWIM) Hs: 6.5 m U: 17.3 m/s Hs: 6.1 m U: 8.8 m/s Hs: 5.8 m U: 22.2 m/s Hs: 5.1 m U: 11.7 m/s Hs: 6.5 m U: 21.0 m/s Prestige SOS 14:00 UTC

Performance quality Estimation errors on wave direction ( Φ ), wave wavelength ( λ ) and energy (E): <15° <10-20% <15% Requirements: 5% 19% 7° 6% 12% 3° 15h 7% 6% 11° 8% 8% 0° 10h 6% 18% 11° 7% 1% 0° 08h 19% 27% 11° 13% 0% 0° 06h - - - 4% 0% 3° 00h E λ Φ E λ Φ WIND SEA SWELL

Conclusions ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

TU3.T10.5.ppt

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TU3.T10.5.ppt