Radar Data Availability for Fiji

Hirdeshni Gautam

Radar Image Processing and Analysis

Overview

• Focus:

– Space-borne Synthetic Aperture Radar (SAR)

• Brief description of SAR Imagery

• Some satellite missions

– Imagery available from these missions

SEASAT (1979)

First Space Borne Radar Mission

SAR Imagery

• It has no colour

• Each pixel records the intensity of the backscatter

• Backscatter is dependent on surface roughness

• By analysing backscatter and different polarisations we can come up with a colour composite image

Rewa Delta, (Sentinel 1) TC

Colour Composite

• Cropped

• Calibrated

• Speckle Filtered

• Terrain Corrected

• RGB, R-VV, G-VH, B-VV

Bands (Wavelengths)

• L Band – wavelength 15-30 cm

– frequency 1-2 GHz.

• S band– wavelength 8-15 cm

– frequency 2-4 GHz.

• C band radars– wavelength 4-8 cm

– frequency 4-8 GHz.

• X band– wavelength 2.5-4 cm

– frequency 8-12 GHz.

What you “see”, depends on the band

Image from http://gsp.humboldt.edu/olm_2015/Courses/GSP_216_Online/images/wavelength.png

Application :

Flood Mapping

Nadi January 2012

Application: Flood Mapping

Semi Automatic Analysis

• Speckle suppression

• Density slicing

• Deleting small areas from “water non water layer” through filter

• Raster to vector conversion

Disaster Response: Fiji Flooding 2016

http://services.gsd.spc.int/fiji

Japanese Aerospace Exploration Agency (JAXA)

• ALOS and ALOS 2

• PALSAR - Phased Array type L-band Synthetic Aperture Radar

• Frequency – 1.2 GHz

• Resolution– PALSAR – 10m

– PALSAR 2 – Spotlight mode (1 to 3 m)

Advanced Land Observation Satellite (ALOS – 2)

Public Private PartnershipGerman Space Agency and Astrium

• Twin Satellites

• acquired data to be used in generating WorldDEM

• Resolution-– SpotLight: up to 1 m

– StripMap: up to 3 m

– ScanSAR: up to 16 m

TerraSAR-X and TanDEM-X

Italian Space Agency (ASI)

COSMO-SkyMed (X Band)

• Four satellites in sun-synchronous polar orbits

• Resolution

– Spotlight modes:

• SPOTLIGHT1, military-only mode

• SPOTLIGHT2 - 1 m

– Two Stripmap modes:

• HIMAGE, 3 and 5 m

• PINGPONG, at 15 m resolution

– Two ScanSAR modes:

• WIDEREGION, 30 m

• HUGEREGION, 100 m

(Constellation of small Satellites for the Mediterranean basin Observation)

European Space Agency (ESA)

Sentinel 1

• C band

• Resolution– Strip Map Mode:

• 5 x 5 m spatial resolution

– Interferometric Wide Swath

• 5x20 m spatial resolution

– Extra-Wide Swath Mode:

• 25 x 100 m spatial resolution

– Wave-Mode:

• 5 x 20 m

Digital Globe (in partnership with MDA)

• RADARSAT 2

• RADARSAT 1 is no longer active

• Frequency Band C-Band (5.405 GHz)

• Resolution of 3m

• Polarization HH, HV, VH, VV

RADARSAT-2

German Military Satelite:SAR Lupe

• 5 satellites in tandem

• Military - reconnaissance satellite imaging

• Data not for public use

• X Band, resolution ~ 50 cm

THANK YOU