OBSERVATIONS JUST AFTER THE GREAT EAST JAPAN EARTHQUAKE

BY THE AIRBORNE SAR (PI-SAR2) OF NICT

T. Kobayashi, T. Umehara, M. Satake, S. Kojima, J. Uemoto,

T. Matsuoka, A. Nadai, and S. Uratsuka

National Institute of Information and Communications Technology (NICT ） , Tokyo, JAPAN

IGARSS2011 July 28 TH4.T07

Outline

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1. Introduction2. Pi-SAR2 characteristics3. Urgent observations by Pi-SAR24. Onboard Processor5. SAR images 6. Summary

Polarimetric and interferometric synthetic aperture radar (Pi-SAR)

1.Introduction

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The great east Japan earthquake occurred on March 11,2011. NICT conducted urgent observations of the damaged areas by an airborne X-band SAR system (Pi-SAR2) on March 12. The observation areas were scattered over a 500 km wide area.

SAR images were processed in flight using the onboard processor. After landing, these SAR images were sent to the head office of NICT, distributed to headquarters for disaster control and uploaded to the website.

The second flight was conducted on March 18 to detect the change of damaged areas and to cover the other areas.

2.Pi-SAR2 characteristics (specifications)

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Since 1997Since 2009

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image by the onboard processor

Onboard image

Kaya ohashi

March 12 2011

Image size: 2 x 2 km

Resolution: 0.3 m

broken bridge

Sendai Airport on March 12

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Pi-SAR2 color composite image 5km x 5km (Sendai Airport, Miyagi)

RGB: HH, VH, VVPath no 2011031204-03place name Sendai AirportDate (data take) March 12/, 2011Location N38 deg 09’ 14’’,

E140 deg 54’ 18’’Altitude 8501 mSpeed 192 m/sTrue heading -7.2degDrift angle 8.28degIncidence angle 38.7 -- 54.2 degImage size (Az x Gr) 5.00 x5.00 km Pixel spacing (Az x Gr)

0.250 x 0.25 m

Resolution Az/Sr 0.30 x 0.30 m

20000x20000x4bytex2=3.2Gbyte for each polarization

3. Urgent observations by Pi-SAR2

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1st flight : 15path7:30 – 10:45 JSTMarch 12 2011

2nd flight : 13path12:00 – 15:30 JST March 18 2011

SAR image on March 12

FlightIllumination

N

image size: 25km x 5 km

Sendai

Path 4 on March 12, 2011

Line corresponding to flight path. Box corresponding to the observation area.

A relationship in terms of location

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TokyoNICT

NagoyaAirport

Center of shake

The 9.0-magnitude earthquake and tsunami occurred on March 11 2011.

NICT office is located in Koganei, Tokyo.

Pi-SAR2 system is kept in Nagoya. Pi-SAR2 uses the airplane owned by a company in Nagoya.

Time table of urgent observation on March12

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Event Handling Time Hrs from obs.

Earth quake 14:46 -Negotiation of flightSetting up Pi-SAR2 systemTraveling from Koganei to Nagoya

Takeoff 07:30 -

Observation 08:16 0Onboard processing

Landing 10:45 2.48Preparing for sending data

Receiving images@NICT

12:14 3.97

Preparing for data release Data Release 14:23 6.12

4.Onboard processor

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Machine DELL Precision T7400

CPU Intel Xeon X5260(3.33GHz, 1333MHzFSB, 6MB L2 cashe)

OS Red Hat Enterprise Linux 5

Memory 12Gbyte

Disk SATA HDD(7200 回転 )

extraction: 2.5 min processing: 10 minfor 2x2 km area by mode 1

about 4 min processing for 1x1 km area by mode 1

The Pi-SAR2 has an onboard processor and data transfer system. This onboard system offers SAR image with full spatial resolution

images by the onboard processor

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Onboard image

Sendai Airport

March 12 2011

Image size: 2 x 2 km

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images by the onboard processor

SAR images were processed in flight using the onboard processor. After landing, these SAR images were sent to the head office of NICT, distributed to headquarters for disaster control and uploaded to the website.

P1:Onahama P10:Kesennuma

P12:Abukumagawa P13:Natori P15:Shirakawa

5. SAR images Temporal Change

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March 12, 2011 March 18, 2011

Sendai airport area 5 x 5 km

Temporal Change of submersion area

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March 12, 2011 March 18, 2011

Submersion(under water) area decreased on March 18.

Comparison with aerial photos

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Photos taken by Geospatial Information Authority of Japan

Comparison with Submersion area

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area covered with waterestimated by aerial photo

(by Geospatial Information Authority of Japan)

SAR image around Sendai airport

SAR image on March 18

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Flight

Illum

inat

ion

image size: 35km x 5 km

Path 9 on March 18, 2011

N

Area damaged by tsunami - Onagawa

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Buildings collapsed by tsunami

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Upper map provided by http://cottostreet.blog.so-net.ne.jp/2011-04-24

7. Summary

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NICT conducted urgent observations for the great east Japan earthquake by Pi-SAR2 on March 12 and March 18 .

SAR images were processed by the onboard processor. These SAR images were distributed to headquarters for disaster control on March 12 and uploaded to the website.

http://www2.nict.go.jp/pub/whatsnew/press/h22/announce110312/index.html

Color composite images observed on March 12 and 18 are also available at the same website.

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Thank you

I would like to offer my deepest condolences on the victims of the east Japan earthquake.

Acknowledgements:We thank NEC Corporation for the Pi-SAR2 system development and Diamond Air Service for the flight. operation.

Amplitude Phase difference Unwrapped Phase difference

Single-pass Intereferometry

Mt. Shinmoe, 5 x 5 km, observed on February 26, 2011

Az

Rg

N

Pi-SAR and Pi-SAR2

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NICT developed and operated the airborne polarimetric and interferometric synthetic aperture radar(Pi-SAR) since 1996 with JAXA. The Pi-SAR made more than 100 observation flights since 1997. Over ten years experiences of NICT in development of Pi-SAR (X-band) and application research have indicated the effectiveness and limitation of remote-sensing of earth surface by existing airborne SAR systems, especially for disaster monitoring such as volcanic eruption, land-slide and flood.

・ Objective: To contribute to application research area such as disaster monitoring by improvement of the SAR system, NICT has developed new high performance airborne SAR system, “Pi-SAR2”since 2006.

Pi-SAR2 system (overview)

Main H Antenna

Main V Antennaleft radome

Sub V Antenna

right radome

SW

HPA(TVTA)

HPA(TVTA) TRX SGP

System Control 　2-Axis Driver Control

Recorder IMU/GPS

(POS AV610)

Power Supply

2-Axis Driver

EatherHUB

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Rack #1

Rack #2

2-Axis Driver

Monitor

Pi-SAR2 system (Antenna & radome)

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●Antenna:V and H polarization slotted waveguide antenna (668mm (Az) x 200mm(El))

●2-axis driver:Off-nadir angle (roll) : 40-60 degAzimuth (yaw): ±9 degAz. ang. velocity:0.1(min)-5(Max) deg/s

●Interferometricbaseline: 2.6 m (Pi-SAR: 2.3 m)Ground height accuracy under 2m are expected at inc. angle of 40deg at altitude of 10000m ( with phase error of 2deg and baseline error of 0.5 mm)

Pi-SAR2 system (TRX, TWTA)

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●Transmitter (Tx) and Receiver (Rx)Gain control: manual/ autoReceive input level: 0dBm ～ -60dBmReceiver unit: 3 sets for Hm, Vm and Vs channel

●Switcher unit and high power amp. (TWTA)On board calibration function is in switcher unit.By using 2 sets of 8 kW (peak) TWT amplifierfor H-and V-pol. transmission independently,transmission duty ratio of each TWTA isreduced.

●2-Axis driver control

Rack #1

Pi-SAR2 system (SGP)

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●Signal generator and processor(SGP)Chirp pulse band width: 500/ 300/ 150MHz Receive sampling rate: 800/ 400/ 200MHz3 sets of signal processor for Hm, Vm and Vs channel

To achieve accurate signal processing , the clock of the D/A and A/D converters are determined as enough higher than the signal frequencies. Moreover, the real A/D conversion is adopted instead of the I-Q method to avoid the influence of non-orthogonality between I-Q channels.

8bit ADC with 1.6GHz sampling12bit DAC with 1.6GHz Clock

●System control (SC)

Rack #1

Pi-SAR2 system (Rcorder)

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● on-board processor

● Monitor

● Power supply

●Data recorder

Data rate: 200 MB/s (Max) x 3 channelRecord media: 4TB 3.5 in. HD (500 GB x 8) for each channelI/O Interface: serial-FPDPEstimated data volume of 4 hour SAR observation:→3 TB per each channel

serial FPDP(Front Pannel Data Port)

Rack #2

Pi-SAR2 system (Operation)

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●Planning and Operation Software

・ Observation plans are made by a laptop-PC with Japanese map.・ Operation of observation is carried out by using the laptop-PC interface.・ According to the observation plan, observation starts automaticallywith real time GPS position information.

Observation mode of Pi-SAR2

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Observation mode Mode 1 Mode 2 Mode 3 Mode 0

Bandwidth 500 MHz 300 MHz 150 MHz 500 MHz

method Strip map Strip map Strip map Sliding spotlight

Slant range resolution 0.3 m 0.5 m 1.0 m 0.3 m

Azimuth resolution 0.3 m (1look) 0.6 m (2looks)

0.6 m (2looks) 0.5 ～ 0.3 m (2looks)

Swath width 5 ～ 10 km 7 ～ 10 km > 10 km 4 ～ 9 km

Azimuth length － － － 3 ～ 7 km

NEσ 0 < -23 dB < -27 dB < -30 dB < -25 dB

*In all modes, Pi-SAR2 acquires full polarimetric (HH/VV/HV/VH) and interferometric (VVs/HVs) data.*Values are estimated with the airplane altitude of 12000 m and the ground speed of 220 m/s

Pi-SAR2 has polarimetric and interferometric functions with high spatial resolution of 0.3-0.6 m in along track (azimuth) direction and 0.3-0.5 m in cross track (slant-range) direction at X-band.Noise equivalent backscattering coefficient (NEσ0) will be kept under -27 dB in slant-range distance of 5-10km between incidence angles from 20 to 60 degree at the platform altitude of 12000 m.

Specification of Pi-SAR/Pi-SAR2

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Pi-SAR2 Pi-SAR (X-band)Center Frequency 9.65/9.55/9.55GHz) 9.55GHzBand width 500/300/150MHz 100/50MHzWeight 537kg (Include INS) 708kg (Include INS)Transmitter peak power 8kW 6.3kWAntenna size (Az x El) 668 x 200 mm 1065 x 200 mmBeam width (Az x El) 3deg x 35 deg 2.3deg x 40 degSlant Range resolution 0.3/0.5/1.0m 1.5/3.0mAzimuth resolution 0.3/0.6/1.2m (1/2/4 look) 1.5/3.0m (4 look)Noise equivalent NRCS less than -23/-27/-30dB less than -40dBD/A conversion for chirp 12bit DAC with 1.6GHz Clock 10bit DAC with 246.9MHz Clock

A/D conversion of Rx Real method8bit ADC with 1.6GHz sampling

I-Q separation method8bit ADC with 123.45MHz sampling

Data recording rate 600(200x3)MByte/secConduant TK400

64(32x2)MByte/secSony DIR-1000

Swath width (ground-range) 7.2/21/42km 5.6km (6ch mode 100MHz)Receiving Channel 3ch(Vm, Hm, Vs) 2ch(Vm, Hm/Vs)Combination of data 6ch(Quad Pol.+XTI) 6ch(Quad Pol.+XTI) 2ch(XTI)

4ch(3ch pol.+XTI/Quad pol)Range of antenna rotation in Yaw ±9degrees ±6.5degreesBaseline for Cross-track interferometry

2.6m 2.3m

Incidence angle 10 --65 deg. Variable 10 --75 deg. VariableFlight information Applanix POS AV610 Litton-92 navigation system

Breakdown of weight

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weight

Main antenna 95 kg

Sub antenna 95 kg

Rack #1 157 kg

Rack #2 162kg

IMU/GPS 8 kg

Wave guide etc. 20kg