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Perspectives dapplications des modes SAR et SARin pour le suivi du niveau des fleuves et leur localisation CNES Journe Altimtrie et Hydrologie 2014 Nicolas Bercher Contact: nicolas.bercher@legos.obs-mip.fr LEGOS, Toulouse, France

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Perspectives d’applications des modes SAR et SARin pour le suivi du niveau des fleuves et leur localisation

CNES– Journée Altimétrie et Hydrologie 2014

Nicolas Bercher

Contact: nicolas.bercher@legos.obs-mip.fr LEGOS, Toulouse, France

Mardi 3 juin 2014

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SLIDE 2

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies Geodesic orbit CryoSat-2 altimeter : SIRAL CryoSat-2 data products

CryoSat-2 flies on a geodesic orbit !

Topex/Poseidon & Jason-2 "virtual stations"

  • N. Bercher

Review of CryoSat-2 applications for hydrology 2 / 16

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SLIDE 3

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies Geodesic orbit CryoSat-2 altimeter : SIRAL CryoSat-2 data products

CryoSat-2 flies on a geodesic orbit !

Envisat "virtual stations"

  • N. Bercher

Review of CryoSat-2 applications for hydrology 2 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies Geodesic orbit CryoSat-2 altimeter : SIRAL CryoSat-2 data products

CryoSat-2 flies on a geodesic orbit !

CryoSat-2 tracks. . . ! (369 days, 7 km //)

  • N. Bercher

Review of CryoSat-2 applications for hydrology 2 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies Geodesic orbit CryoSat-2 altimeter : SIRAL CryoSat-2 data products

CryoSat-2 altimeter : SIRAL

SIRAL basics The most advanced nadir altimeter ! Ku band 20 Hz tracking cycle → 20 Hz L2 products SIRAL : 3 exclusive measurement modes LRM : Wf : 128 bins, Res. : 200 km2, L2 : 20 Hz SAR : Wf : 128 bins, Res. : 3 km2, L2 : 20 Hz SARin : Wf : 2×512 bins (dual channel), Res. : 3 km2, L2 : 20 Hz + retracked echo (lat,lon)

  • N. Bercher

Review of CryoSat-2 applications for hydrology 3 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies Geodesic orbit CryoSat-2 altimeter : SIRAL CryoSat-2 data products

CryoSat-2 modes mask

LRM : ≈ 66% – SAR : ≈ 17% – SARin ≈ 17%

  • N. Bercher

Review of CryoSat-2 applications for hydrology 4 / 16

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SLIDE 7

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies Geodesic orbit CryoSat-2 altimeter : SIRAL CryoSat-2 data products

CryoSat-2 modes mask

LRM : ≈ 66% – SAR : ≈ 17% – SARin ≈ 17%

  • N. Bercher

Review of CryoSat-2 applications for hydrology 4 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies Geodesic orbit CryoSat-2 altimeter : SIRAL CryoSat-2 data products

CryoSat-2 data products (and their use in hydrology)

ESA Official L2 products (Baseline B, since Feb. 2012)

Product files for LRM, SAR & SARin modes Use : spatio-temporal time series, longitudinal & transversal river profiles, validation : (SAR :) along-track resolution, (SARin :) cross-track angle

CNES CPP (CryoSat Processing Prototype)

11 months of GDR-D-like products for LRM, SAR & RDSAR modes Use : SAR / Reduced-SAR comparison and assessment

ESA/ESRIN Sentinel-3 prototype

Data samples : stack matrices, L1B 20 Hz & 80 Hz (waveforms), L2 (Samosa retracker outputs) Use : exploring stack applications (surface roughness & classification), along-track resampling (spotlight), etc.

  • N. Bercher

Review of CryoSat-2 applications for hydrology 5 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

LRM vs. SAR : waveforms

Doppler beam

1 doppler WF = a coherent sum of 64 Brown's WF

Sum of Energy of 91 WF (made on board) 1970hz/91 = 20hz Coherent sum f(E,φ) of 64 WF ''focalized'' at each ground cell (made off line) 300m

SAR LRM

∑E dφ + ∑E

  • N. Bercher

Review of CryoSat-2 applications for hydrology 6 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

LRM vs. SAR : waveforms

Doppler beam footprint

from Radar Altimetry Tutorial, Rosmorduc et all. 2011

SAR wave-form much more « peaky » than Brown's wave-form (because of surface reduction from internal to external rings)

Bin number Power

Brown wave-form Doppler wave-form

Power Bin number

  • N. Bercher

Review of CryoSat-2 applications for hydrology 6 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

The multi-look over one ground cell

from K. Raney/S. Dinardo

1 burst 1 doppler beam 1 ground cell strip of 300m 1 burst every 84m

Each ground cell can be seen per theoriticaly 256 bursts (~223 in practice over ocean)

254 bursts (~20km) burst footprint ~20km (64*300m)

  • N. Bercher

Review of CryoSat-2 applications for hydrology 7 / 16

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SLIDE 12

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

The multi-look: stack

∑ ∑

L1b product

  • N. Bercher

Review of CryoSat-2 applications for hydrology 7 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

The multi-look : the stack

Bin number Bin number Power Bin number

2 doppler wave-forms « looking » the same ground cell

1 256 look number Power Bin number

2 Doppler waveforms « looking » the same ground cell

256 bursts

  • N. Bercher

Review of CryoSat-2 applications for hydrology 7 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

Stack: mean waveform

Land decontamination

SAR waveforms Index selection

  • N. Bercher

Review of CryoSat-2 applications for hydrology 7 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

Offset depending on pitch mispointing Aperture depending

  • n sea surface

RMS slope

power

  • 0.8 -0.4 0 0.4 0.8

look angle (deg)

The multi-look: stack look-angles

  • N. Bercher

Review of CryoSat-2 applications for hydrology 7 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

Stack: surface roughness

roughness power

  • N. Bercher

Review of CryoSat-2 applications for hydrology 7 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

Product Levels

L0 / FBR SAR Retracking

Range Stack (1/2) 256 ground cell views Bursts 64 echoes Brown WF(I,φ)

Merge SAR echoes

Waveforms 128 samples Waveforms & Phase diff. 2×512 samples each

Range migration 1Hz-20hz products

Cross-track Angle / Coords (retracked bin, L2I only)

SAR mode SARin mode

L1b L2 / L2I

Doppler Beams SAR WF(I)

Hamming filter (opt.)

SAR coherent sum ...the “same” for 2 channels... two reception antennas, 64 look angles instead of 256 Mean waveform

Stack (2/2) 256 ground cell views

Telemetry r α,lat,lon

Multi-look

  • N. Bercher

Review of CryoSat-2 applications for hydrology 8 / 16

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SLIDE 18

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies LRM vs. SAR : waveforms SAR stacking, look angle

Product Levels

L0 / FBR SAR Retracking

Range Stack (1/2) 256 ground cell views Bursts 64 echoes Brown WF(I,φ)

Merge SAR echoes

Waveforms 128 samples Waveforms & Phase diff. 2×512 samples each

Range migration 1Hz-20hz products

Cross-track Angle / Coords (retracked bin, L2I only)

SAR mode SARin mode

L1b L2 / L2I

Doppler Beams SAR WF(I)

Hamming filter (opt.)

Stacks of 2×64 ground cell views

SAR coherent sum ...the same for 2 channels... (two reception antennas) Mean waveform

Stack (2/2) 256 ground cell views

Telemetry r α,lat,lon

Intermediate stack 2×64 ground cell views

Multi-look

  • N. Bercher

Review of CryoSat-2 applications for hydrology 8 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies

External data Geo-masks : SWBD, MODIS/MOD44W, etc. For : river width, inundation, river bed that moves a little throught time (e.g., SWBD already is wrong for some places) Can be hard to get synced in space & time with altimetry What about altimetry itself ?

  • N. Bercher

Review of CryoSat-2 applications for hydrology 9 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies

External data Geo-masks : SWBD, MODIS/MOD44W, etc. For : river width, inundation, river bed that moves a little throught time (e.g., SWBD already is wrong for some places) Can be hard to get synced in space & time with altimetry What about altimetry itself ?

SAR look-angles

  • N. Bercher

Review of CryoSat-2 applications for hydrology 9 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies

External data Geo-masks : SWBD, MODIS/MOD44W, etc. For : river width, inundation, river bed that moves a little throught time (e.g., SWBD already is wrong for some places) Can be hard to get synced in space & time with altimetry What about altimetry itself ?

SAR look-angles SARin crosstrack angle. . .

  • N. Bercher

Review of CryoSat-2 applications for hydrology 9 / 16

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SLIDE 22

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies

External data Geo-masks : SWBD, MODIS/MOD44W, etc. For : river width, inundation, river bed that moves a little throught time (e.g., SWBD already is wrong for some places) Can be hard to get synced in space & time with altimetry What about altimetry itself ?

SAR look-angles SARin crosstrack angle. . .

Remark about Sea Ice : “leads” are just like “moving rivers” and requires synced geo-masks (∆t < 1 day).

  • N. Bercher

Review of CryoSat-2 applications for hydrology 9 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : can SAR help ?

Stack: surface roughness

roughness power

  • N. Bercher

Review of CryoSat-2 applications for hydrology 10 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : can SAR help ?

Stack: surface roughness

roughness power

➔ Surface response classification ? ➔ River extent detection ?

  • N. Bercher

Review of CryoSat-2 applications for hydrology 10 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : SARin may help

SARin data extraction : tracks are zigzagging. . .

  • N. Bercher

Review of CryoSat-2 applications for hydrology 11 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : SARin may help

SIRAL tracks a significant part the hydrographic network !

  • N. Bercher

Review of CryoSat-2 applications for hydrology 11 / 16

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SLIDE 27

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : SARin may help

SIRAL tracks a significant part the hydrographic network !

  • N. Bercher

Review of CryoSat-2 applications for hydrology 11 / 16

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SLIDE 28

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : SARin may help

SIRAL tracks a significant part the hydrographic network !

  • N. Bercher

Review of CryoSat-2 applications for hydrology 11 / 16

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SLIDE 29

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : SARin may help

30 m wide rivers we can actually hardely see. . .

  • N. Bercher

Review of CryoSat-2 applications for hydrology 11 / 16

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SLIDE 30

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : SARin may help

Zoom-in examples. . .

  • N. Bercher

Review of CryoSat-2 applications for hydrology 11 / 16

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SLIDE 31

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : SARin may help

Zoom-in examples. . .

  • N. Bercher

Review of CryoSat-2 applications for hydrology 11 / 16

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SLIDE 32

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : SARin may help

Zoom-in examples. . .

  • N. Bercher

Review of CryoSat-2 applications for hydrology 11 / 16

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SLIDE 33

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Geo-localization of waterbodies : SARin may help

Zoom-in examples. . .

  • N. Bercher

Review of CryoSat-2 applications for hydrology 11 / 16

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SLIDE 34

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Conclusion

Benefits of the mission for hydrology Cryosat-2 : geodesic orbit with dense spatial coverage SIRAL : rich instrument with SAR & SARin modes SAR : 64× higher resolution than LRM, peaky echoes SARin : retracked echo coordinates (lat,lon) Products L1b, L2 : no stack matrix ! But interesting params in L1b Many products : ESA, CNES/CPP , NOAA/RADS, ESRIN (proto) Dealing with data spatio-temporal availability is confusing at times !

  • N. Bercher

Review of CryoSat-2 applications for hydrology 12 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Perspectives regarding SAR & SARin

A new look at the rivers Peaky echoes, resolution. . . What about hooking ? What parabolas in range chronograms ? Bias between SAR and current LRM missions ? Explore swath processing / 3D rugosity maps from SARin/L1b, a step toward Swot. . .

  • N. Bercher

Review of CryoSat-2 applications for hydrology 13 / 16

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SLIDE 36

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Perspectives regarding SAR & SARin

A new look at the rivers Peaky echoes, resolution. . . What about hooking ? What parabolas in range chronograms ? Bias between SAR and current LRM missions ? Explore swath processing / 3D rugosity maps from SARin/L1b, a step toward Swot. . . Validation How much is the benefice of SAR over LRM ? Is SARin crosstrack angle accurate enough ? (slopes) Validation : is a complex task for geodesic orbits !

  • N. Bercher

Review of CryoSat-2 applications for hydrology 13 / 16

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SLIDE 37

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Perspectives regarding SAR & SARin

A new look at the rivers Peaky echoes, resolution. . . What about hooking ? What parabolas in range chronograms ? Bias between SAR and current LRM missions ? Explore swath processing / 3D rugosity maps from SARin/L1b, a step toward Swot. . . Validation How much is the benefice of SAR over LRM ? Is SARin crosstrack angle accurate enough ? (slopes) Validation : is a complex task for geodesic orbits ! And SARin mode won’t last : there’s no SIRAL-2 planned !

  • N. Bercher

Review of CryoSat-2 applications for hydrology 13 / 16

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SLIDE 38

– Thank you ! –

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SLIDE 39

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Mekong river (SAR)

  • N. Bercher

Review of CryoSat-2 applications for hydrology 15 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Mekong river (SAR)

River Water level profile

  • N. Bercher

Review of CryoSat-2 applications for hydrology 15 / 16

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Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Mekong river (SAR)

Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan2013 Feb 200 400 600 800 1000 20 40 60 80 100 120

Distance to ocean (km)

CryoSat-2 SAR - Mekong river water level Z(x,t)

Time Z (m)

CryoSat-2 interpolated Z (cubic) CryoSat-2 Z 20 40 60 80 100 120

  • N. Bercher

Review of CryoSat-2 applications for hydrology 15 / 16

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SLIDE 42

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Congo river (SARin)

Source Wikipedia.org

  • N. Bercher

Review of CryoSat-2 applications for hydrology 16 / 16

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SLIDE 43

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Congo river (SARin)

  • N. Bercher

Review of CryoSat-2 applications for hydrology 16 / 16

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SLIDE 44

Introduction to CryoSat-2 SAR & SARin modes Localization of waterbodies External data Can SAR help ? SARin may help !

Congo river (SARin)

River Water level profile

  • N. Bercher

Review of CryoSat-2 applications for hydrology 16 / 16