International Conference on Space (ICS) – 2014, Islamabad
On the Use of ALOS-PALSAR Mosaics
to Study Ocean Surface Features of
Pakistan Coastal Region
Jibran Khan1 and Waqas A. Qazi2
1Lecturer,
Dawood University of Engineering & Technology, Karachi
M.Phil. Scholar, ISPA, University of Karachi.
[email protected]
2Assistant
Professor, Department of Space Science
Institute of Space Technology, Islamabad
http://grel.ist.edu.pk
Contents
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Introduction
Data
Area of Interest
Methodology
Results
Conclusions
Introduction
• Knowledge of ocean surface features is vital
for coastal management applications
• Pakistan coastal region plays an important role
in Asian monsoon and biological productivity
• Not many remote sensing studies describing
physical oceanographic features of this region
Introduction
• Synthetic Aperture Radar (SAR) offers a
unique solution to study ocean surface
features due to:
 all-weather observation capability (except rain)
 high resolution
not affected by dust storms
Basic Mechanism of SAR Ocean
Imaging (Bragg Scattering)
Illustration of Bragg Scattering; Where, λ r is the Radar wavelength, λB is the sea surface wavelength, θ
is the local angle of incidence (Adapted from Martin, 2004)
The PALSAR Instrument
• PALSAR is an active microwave SAR instrument that
uses L-band frequency to perform cloud-free
observations
• PALSAR was onboard JAXA’s first Advanced Land
Observation Satellite (ALOS-1)
ALOS – I Configuration (Source: JAXA)
Datasets Used
• Phased Array L-Band SAR (PALSAR) intensity
mosaic data from 2010
– 50 m resolution
– Acquired from JAXA
• Moderate Resolution Imaging Spectrometer
(MODIS) Sea Surface Temperature (SST) ocean
products
– Day time SST Level 2 products from NASA
– 1 Km resolution
Area of Interest (AOI)
PALSAR HH Polarization Intensity Mosaic of Area of Interest © JAXA
Methodology
Extraction of Acquisition Dates of PALSAR
Intensity Mosaic
Visual assessment of PALSAR Intensity Mosaic
Identification of ocean surface features of PALSAR
imagery
Validation of identified ocean features using
MODIS data
Extraction of Acquisition Dates for
PALSAR Mosaic Image
24th August
2010
PALSAR intensity mosaic of 24th August 2010
Acquisition dates of 2010 PALSAR intensity mosaic i.e.,
5th September 2010 (right), 1st May 2008 (center) and
24th August 2010 (left)
Identifying Ocean Surface Features in PALSAR
Mosaic Imagery – SST Front
Front identification in 24th August 2010 PALSAR mosaic (left most part)
Validating SST Front using MODIS SST Products
MODIS True Color Images of respective dates showing cloud obscuration,
which was a limitation in comparison process
Validating SST Front using MODIS SST Products
MODIS Level-2 SST image (26th August 2010) of the study area where signature of front is
clearly visible (left) Quality levels SST image of the same date and location (right) where SST
Is found to be reliable (0 being most reliable and 4 being unacceptable SST)
Validating SST Front using MODIS SST Products
Location of SST front at approximately 20 Kilometers from the coast in PALSAR
HH polarization intensity image of 26th August 2010
Validating SST Front using MODIS SST Products
Location of SST front at same location of approximately 20 Kilometers from
the coast in MODIS Level-2 SST image of 26th August 2010
Validating SST Front using MODIS SST Products
Location of SST front at same location of approximately 20 Kilometers from the coast in both PALSAR HH polarization
intensity image (top) and MODIS Level-2 SST image of 26th August 2010 (bottom)
Identifying Ocean Surface Features in PALSAR
Mosaic Imagery – Fresh Water Outflows
Identifying Ocean Surface Features in PALSAR
Mosaic Imagery – Ships
Summarizing the Results
False color PALSAR intensity mosaic summarizing results of identified ocean surface features
with better visualization
Conclusions
• Phased Array L-Band SAR intensity mosaicked
image has been used to study ocean dynamics
along Pakistan coastal region
• Fresh water outflows, SST front and some
ships along Karachi coast have been identified
• Some other interesting ocean surface features
were also identified that are to be explored
further
Conclusions
• Study highlighted the immense potential of
PALSAR to analyze ocean surface dynamical
features
• This preliminary study would open news doors
to further explore ocean dynamics in this
important region utilizing SAR imagery
Thank You!
Questions / Comments?