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Use of ALOS-PALSAR for Oceanography

Remote Sensing Technology Institute German Aerospace Agency, DLR-Germany

S.Lehner, S.Brusch, Li XiaoMing, T. König

Institut für Methodik der Fernerkundung bzw. Deutsches Fernerkundungsdatenzentrum

Folie 2Institut für Methodik der Fernerkundung

Line detection Scatterometer Algorithm,

CMOD

Empirical,Inversion Individual

Along Track Interferometry

Doppler

Currents Coast LineOil Detection

Sea StateHs, 2D, Hmax

Wind Field

13.00o 13.50o 54.50o

54.75o

12.50o 13.00o 13.50o 54.50o

54.75o

12.50o

SAR Processor

SAR Oceanography Algorithms

ShipDetection

IntensitySpeedWake



Detection of Ocean Waves

Sao Miguel

ALOS-PALSAR image acquired on Jan, 07 2007 HH-Polarization; (70kmx70km)

Subscene of ~ 4x4km with moving waves

left: ocean wave spectrum

N

200m

400m



Detection of Waves

Background:

DWD model SWH

White Arrows:

Wave direction of wind sea

Black Arrows:

Wave direction of swell



Wind Field Estimation from L-Band SAR Images

Wind streakdetectionSAR image Wind direction

SAR imagecalibration

Normalized RadarCross Section

Incidence angle

Inversionof

L-MOD

WindSpeed



Influence of Atmosphere, Rain

SIR C / X- SAR Mission



Elbe and Weser Estuary,Nov, 02 2006

Error < 2m/s, operational Research: CMOD5 / XMOD Saturation Rain, Snow, Sea State

ENVISAT ASAR

High Wind Speed CASES ENVISAT ASAR and TerraSAR-X

Polar Low, Trondheim,Mar, 15 2005

TerraSAR-X image acquired on July, 23 2007 at 05:33 UTC over the Baltic sea



Wind Field Estimation from L-Band SAR Images

ALOS-PALSAR image acquiredon Jan, 07 2007 HH-Polarization; (70kmx70km)incidence angle: 38°

N

Quikscat Wind FieldJan, 07 2007

wind direction (~3m/s)

Wind speed vs NRCS for different spectral models(Thompson, 2008)



Shipdetection - ships are bright spots

Double bouncing

SAR

Strong radar return from ships



Shipdetection - Constant false Alarm Rate Detectors (CFAR)

Target window(big enough to contain ships)

Guard window(separate ships from background pixels)

Background window(compute background statistics)

Sliding windows:



Ship detection

Ios

Thira

Keros

ALOS-PALSAR image acquired on Jun, 13 2007 at 20:45:02,HH-Polarization; (70kmx40km)

Subscene with detected ship



ALOS-PALSAR (subscene of around 20 km x 15 km)12-APR-2007 21:28:30 UTC; Polarimetry mode;Proccessing Facility: Japan JAXA; HH-Polarization

TerraSAR-X Spotlight (10km x 10km)River Elbe, Germany2008-03-20 at 05:50:34 UTCHH- Polarization

Elbe River Estuary – L-Band vs X-Band



Summary - Oceanography Algorithms available for SAR

Toolbox - Input, Quicklook generation- General Image Analysis

Windfield Analysis - Calibration- Streak Detection – Wind Direction- Wind Field- New XMOD Algorithm

Ship and Oil Detection- Threshold Algorithm (CFAR)- Complex Phase Information- Multipol. Algorithms

Sea State- Two Dimensional Spectra- Determination of Peak parameters-Integrated parameters

Currents- Feature Detection- SLC Analysis



The Zero Doppler Geometry for PALSAR SLC images.

A.Parizzi, M. Eineder



The Geometry of a SAR SLC image.



The Geometry of a SAR SLC image.(2)

Doppler Centroid Geometry Zero Doppler Geometry



The Geometry of a SAR SLC image.(3)

ΔΨ

t0

t0+ tc

r0

R(t0,r0)

Where:



Azimuth Shift to Zero-Doppler

master

slave

⎟⎟⎠

⎞⎜⎜⎝

⎛ΔΨ−= )sin(

rel

DCDCZD v

RgAzAz



Geocoding