National Aeronautics and Space Administration

www.nasa.gov

ARSET Applied Remote Sensing Training http://arset.gsfc.nasa.gov @NASAARSET

Synthetic Aperture Radar for Rapid Flood Extent Mapping

Sang-Ho Yun

ARIA Team Jet Propulsion Laboratory California Institute of Technology

National Aeronautics and Space Administration Applied Remote Sensing Training Program 2

Atmospheric Windows & Current SAR Missions

TerraSAR-X COSMO-SkyMed Radarsat-2 Sentinel-1A ALOS-2

X-band (3 cm)

C-band (6 cm)

L-band (24 cm)

S-band (12 cm)

γ-rays, x-rays infrared microwave

visible

KOMPSAT-5

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Earth is Mostly Cloudy

Average cloudiness over Earth in April 2015 seen from Aqua Satellite. At any given time, around 70% of the Earth is covered by clouds.

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And Half Dark

At any given time, 50% of the earth is dark.

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Radiation Pattern

θx

θy

Antenna

Radiation pattern

U

x

y

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Some Imaging Radar Jargon SAR antenna

-3dB

footprint

swath look angle

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Real Aperture Radar Synthetic Aperture Radar

…

Synthetic Aperture Radar (SAR)

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Real Aperture Radar

Synthetic Aperture Radar

…

Synthetic Aperture Radar (SAR)

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SAR image (amplitude)

SAR processing

Raw data (complex)

Amplitude Phase

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Microwave Scattering (Smooth)

h < λ/2 Dark

λ

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Bright

Microwave Scattering (Rough)

h < λ/2

λ

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Darker

Floods Form Smooth Surface

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Brighter

Floods with Tall Vegetation

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Brighter

Floods with Artificial Structure

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SAR Image (Before)

©ALOS-2 Operation and Data Distribution Consortium, Original Data

provided by JAXA

ALOS-2 2015-09-30

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SAR Image (After)

©ALOS-2 Operation and Data Distribution Consortium, Original Data

provided by JAXA

ALOS-2 2016-01-06

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Flood Extent Maps

•  DerivedfromALOS-2SARData•  2016-01-06datacomparedto2015-09-30

•  ProcessingLevel:1.5•  Coverage:70kmx240km•  ResoluIon:~12m•  AreaofpotenIalfloods:Blue+Red

•  Bluepolygons:Floodswithsmoothsurface

•  Redpolygons:FloodswithtallvegetaIon OriginaldataprovidedbyJAXA

•  Productformats•  KMZ(Polygons)•  KMZ(PNGimage)•  GeoTiff•  Shapefile

•  Availabletodownloadath_p://aria-share.jpl.nasa.gov/events/20160111-US_Midwest_Floods/

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Google Earth NASA Flood Map

Flood Extent Map

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JAXA Flood Map NASA Flood Map

Flood Extent Map

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SAR Data Acquisition Latency

1993 1998 2004 2009 2015 20200

1

2

3

4

5

6

7

8

TerraSAR−X (X/11)TanDEM−X (X/11)

PAZ (X/11)TerraSAR−X Next Gen. (X/11)

HRWS (X/11)KOMPSAT−5 (X/28)

KOMPSAT−6 (X/28)COSMO−SkyMed 1 (X/16)

COSMO−SkyMed 2 (X/16)COSMO−SkyMed 3 (X/16)

COSMO−SkyMed 4 (X/16)COSMO−SkyMed Sec. Gen. 1 (X/16)

COSMO−SkyMed Sec. Gen. 2 (X/16)ERS−1 (C/35)

ERS−2 (C/35)Envisat (C/35)

Envisat−ext (C/30)Sentinel−1A (C/12)

Sentinel−1B (C/12)Sentinel−1C (C/12)

Sentinel−1D (C/12)RADARSAT−1 (C/24)

RADARSAT−2 (C/24)RADARSAT Constellation 1 (C/12)RADARSAT Constellation 2 (C/12)RADARSAT Constellation 3 (C/12)

NISAR (LS/12)ALOS−1 (L/46)

ALOS−2 (L/14)ALOS−3 (L/14)

SAOCOM−1A (L/16)SAOCOM−1B (L/16)

Tandem−L 1 (L/8)Tandem−L 2 (L/8)

Year

Day

s

L - band C - bandX - bandS - band

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Summary

•  Radar sensors see through clouds day and night.

•  Synthetic Aperture Radar achieves high resolution (3 – 20 m) over a wide swath (50 – 250 km).

•  SAR amplitude is sensitive to floods, with pixel values becoming either darker or brighter.

•  Achievable SAR data acquisition latency is already less than a day

Copyright 2016 California Institute of Technology. Government sponsorship acknowledged.

Copyright 2016 California Institute of Technology. Government sponsorship acknowledged.