Use of ALOS-PALSAR for Oceanography

Transkript

1 Use of ALOS-PALSAR for Oceanography Remote Sensing Technology Institute German Aerospace Agency, DLR-Germany S.Lehner, S.Brusch, Li XiaoMing, T. König

2 SAR Oceanography Algorithms SAR Processor Wind Field Sea State Hs, 2D, Hmax Currents Coast Line Oil Detection Ship Detection Scatterometer Algorithm, CMOD Empirical, Inversion Individual Along Track Interferometry Doppler Line detection Intensity Speed Wake o o o o o o o o o o Folie 2

3 Detection of Ocean Waves Sao Miguel 200m 400m Subscene of ~ 4x4km with moving waves left: ocean wave spectrum N ALOS-PALSAR image acquired on Jan, HH-Polarization; (70kmx70km) Folie 3

4 Detection of Waves Background: DWD model SWH White Arrows: Wave direction of wind sea Black Arrows: Wave direction of swell Folie 4

5 Wind Field Estimation from L-Band SAR Images SAR image Wind streak detection Wind direction SAR image calibration Normalized Radar Cross Section Inversion of L-MOD Wind Speed Incidence angle Folie 5

6 Influence of Atmosphere, Rain SIR C / X- SAR Mission Folie 6

7 High Wind Speed CASES ENVISAT ASAR and TerraSAR-X Error < 2m/s, operational Research: CMOD5 / XMOD Saturation Rain, Snow, Sea State ENVISAT ASAR Elbe and Weser Estuary, Nov, Polar Low, Trondheim, Mar, TerraSAR-X image acquired on July, at 05:33 UTC over the Baltic sea Folie 7

8 Wind Field Estimation from L-Band SAR Images wind direction (~3m/s) N Quikscat Wind Field Jan, ALOS-PALSAR image acquired on Jan, HH-Polarization; (70kmx70km) incidence angle: 38 Wind speed vs NRCS for different spectral models (Thompson, 2008) Folie 8

9 Shipdetection - ships are bright spots SAR Double bouncing Strong radar return from ships Folie 9

10 Shipdetection - Constant false Alarm Rate Detectors (CFAR) Sliding windows: Target window (big enough to contain ships) Background window (compute background statistics) Guard window (separate ships from background pixels) Folie 10

11 Ship detection Ios Keros Thira ALOS-PALSAR image acquired on Jun, at 20:45:02, HH-Polarization; (70kmx40km) Subscene with detected ship Folie 11

12 Elbe River Estuary L-Band vs X-Band ALOS-PALSAR (subscene of around 20 km x 15 km) 12-APR :28:30 UTC; Polarimetry mode; Proccessing Facility: Japan JAXA; HH-Polarization TerraSAR-X Spotlight (10km x 10km) River Elbe, Germany at 05:50:34 UTC HH- Polarization Folie 12

13 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 Sea State - Two Dimensional Spectra - Determination of Peak parameters -Integrated parameters Currents - Feature Detection - SLC Analysis Ship and Oil Detection - Threshold Algorithm (CFAR) - Complex Phase Information - Multipol. Algorithms Folie 13

14 The Zero Doppler Geometry for PALSAR SLC images. A.Parizzi, M. Eineder Folie 14

15 The Geometry of a SAR SLC image. Folie 15

16 The Geometry of a SAR SLC image.(2) Doppler Centroid Geometry Zero Doppler Geometry Folie 16

17 The Geometry of a SAR SLC image.(3) t 0 +t c ΔΨ R(t 0,r 0 ) r 0 t 0 Where: Folie 17

18 Azimuth Shift to Zero-Doppler Az ZD Rg DC = Az sin( ΔΨ) DC vrel master slave Folie 18

19 Geocoding Folie 19