Transcript REMS 6022 * Lab 4 BILKO * internal waves tutorial

REMS 6022 – Lab 4
NEST – Interferometric Synthetic
Aperture Radar Exercises
I hope its ok to do these InSAR exercises as the lab. I kept getting
errors in the oil slick lab. It wouldn’t let me proceed past the oil
detection tool, the software kept crashing.
Venessa Bennett
InSAR Course - Overview
Two training exercises are summarized in the following presentation. The exercise represent
training in the use of the NEST SAR toolbox developed by ESA.
Exercise 1 is the generation of an Interferogram on Etna Volcano and exercise 2 is the generation
of an interferogram of the BAM earthquake.
BACKGROUND
Radar interferometry: Study of interference patterns caused created by combining two
sets of radar signals.
Interferogram: When two interferometric radar data sets are combined the first product
made is called an interferogram
InSAR - Theory
• Interferometric Synthetic Aperture Radar (InSAR) is a geodetic technique that can
identify movements of the Earth's surface
• Observations of surface movement made using InSAR can be used to detect,
measure, and monitor crustal changes associated with geophysical processes such as
tectonic activity and volcanic eruptions
• Ground subsidence caused by anthropogenic influences such as groundwater or
hydrocarbon extraction can also be identified with InSAR
• When combined with ground-based geodetic monitoring, such as GPS, InSAR can
identify surface movements of millimetre to centimetre scale with high spatial
resolution.
SOURCE: http://www.ga.gov.au/scientific-topics/positioningnavigation/geodesy/geodetic-techniques/interferometric-synthetic-aperture-radar
InSAR - Theory
• InSAR uses two or more Synthetic Aperture Radar (SAR) images of an area to identify
surface movements through time.
• Remote sensing satellites that collect SAR imagery transmit pulses of microwave
energy to the Earth's surface and record the amount of backscattered energy.
• SAR images contain information on the Earth's surface in the form of the amplitude
and phase components of the backscattered radar signal
• The amplitude image records information on the terrain slope and surface roughness,
while the phase image records information on the distance between the satellite and
the Earth's surface.
SOURCE: http://www.ga.gov.au/scientific-topics/positioningnavigation/geodesy/geodetic-techniques/interferometric-synthetic-aperture-radar
InSAR - Theory
•
Differential InSAR uses two SAR images of the same area acquired at different times. If the
distance between the ground and satellite changes between the two acquisitions due to surface
movement, a phase shift will occur
SOURCE: http://www.ga.gov.au/scientific-topics/positioningnavigation/geodesy/geodetic-techniques/interferometric-synthetic-aperture-radar
InSAR - Theory
www.volcano.si.edu
InSAR - Theory
http://vldb.gsi.go.jp/sokuchi/sar/mec
hanism/interpretation-e.html
InSAR - Theory
Exercise 1: Generation of an interferogram on ETNA Vulcano, Sicily
(Italy), using a ERS1&2 couple acquired on 1/2 August 1996.
IMAGE 1 Acquisition start : 01-Aug-1995 21:16:47.897
IMAGE 2 Acquisition start: 02-Aug-1995 21:16:50.666
STEPS
1. DATA PREPARATION
• Load data
• Create new project
• Apply ephemeris information to data
• coregister both input images (cubic convolution resampling method)
2. GENERATE INTERFEROGRAM
• Use InSAR Tools to generate flattened interferogram
• Estimate coherence between 2 input images and compare two images
(two wave sources are coherent if they have a constant phase difference and the same frequency)
• Carry out topographic phase removal
• Complete multilook analysis
• Geocode and Review in Google Earth
Mt Etna Interferograms
Mt Etna Interferogram
Coherence
Mt Etna Interferogram vs Coherence
Mt Etna Topographic Phase Removal
Mt Etna Topographic Phase Removal
Mt Etna Multilook
Does not work in NEST 5.1 as in NEST 4B-1
Mt Etna Geocode and Review in Google Earth
Exercise 2: Generation of DInSAR inteferogram of the BAM
earthquake
IMAGE 1 Acquisition start 03-Dec-2003 06:13:06.358
IMAGE 2 Acquisition start: 11-Feb-2004 06:13:03.504
Graph builder is used to process the data
1. DATA PREPARATION
• Load data
• Create new project
• coregister both input images (cubic convolution resampling method)
2. GENERATE INTERFEROGRAM
• Use InSAR Tools to generate flattened interferogram
• Estimate coherence between 2 input images and compare two images
3. Hue Saturation Intensity Visualization
Graph Builder Model
BAM flattened Interferogram & Coherence Images
Mt Etna Interferogram vs Coherence
HSV Visualization