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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
COASTAL CURRENTS MONITORING USING RADAR SATELLITES BASED ON
WAVE TRACKING APPROACH
A. Abedini', M. Aghamohamadnia , M. Sharifi, S. Farzaneh
Dept. of Surveying and Geomatics, Faculty of Engineering, University of Tehran, Tehran, Iran
(aabedeni, maghamohamadnia, sharifi, farzaneh) @ ut.ac.ir
Commission VIII/4
KEY WORDS: Coastal Currents, Monitoring, Jason] Satellite, Wave Tracking, Radar Satellites
ABSTRACT:
Use of high resolution radar imagery for coastal currents monitoring has been known as an active topic in several research
institutions. In this study, we demonstrate a new method for coastal currents monitoring based on current tracking by deformed wave
reconstruction.
The magnitude and shape of the echoes (or waveforms) hold information regarding the surface characteristics that can be described
analytically. Accordingly from this shape, several parameters can be construed, by comparing the real waveform with the theoretical
curve. Safety in coastal zones containing coastal engineering for construction of ports, marine structures, beach erosion, natural
hazards, and environmental problems are the issues related to hydrodynamic studies of currents, waves, and winds. Therefore,
monitoring of coastal currents is very important .The ability of the internet to accompany our results to track past and near real-time
movements of every coastal waters for monitoring is appropriate. Surface Current Mapping is utilized using an interface to radar
altimetry data derived surface currents. Then Data access is available in a number of formats and protocols such as Google Earth
KML and so on. In this study Jason! satellite data has been used as input data for assessing the coastal environment.
1. INTRODUCTION
ltimetry is basically a technique for measuring height.
Satellite radar altimetry measures the time taken by a
radar pulse to travel from the satellite antenna to the
surface and back to the satellite receiver. Moreover, this
measurement yields a wealth of other information that can be
used for a wide range of applications tm,
Many current studies are attempting to enhance the quality of
altimetry data close to the coasts. New processing methods and
applications can then be developed for littoral and shallow-
water regions, some of the most fragile and important areas of
the oceans.
There is a shortage of altimetry data near the coasts (or their
inferior quality) which is caused due to several factors:
The technique itself, since the radar echoes reflected off water,
and off a combination of water and land are not identical, and
basically only the former undergo processing by the ground
segments.
Other altimetry satellite measurements also suffer from the same
problem, such as those from the radiometer (at a distance of
about 50 km from the coast) *. But even this amount of data
needs to be used in a way which is effective and efficient.
Since the satellite altimetry and radar observatory came to
existence, various approaches have been offered to use their
data in solving environmental problems and at most to construe
and derive out valuable and profiting information to use in
various areas of research.
An alternative method for calculating surface currents is
through the exploitation of the Doppler shift in synthetic
aperture radar data (Chapron, 2005) P! This method has
! Corresponding author
promise in particular for coastal zones, although there are many
technical challenges, including isolating the surface currents
from signals such as wave orbital motion or tides.
Another method is a feature tracking algorithm to monitor
ocean currents by using satellite sequential images of surface
water (V.M.Krasnopolsky and et all, 1999) A
One area of research is in waveform re-tracking reprocessing
individual satellite track signals to recover the distorted
waveform as it reaches land (Deng and Featherstone, 2006) DI
One of the new ways of monitoring the coastal areas with radar
technology is using the HF radar monitoring system. HF radar
tracks currents and eddies of coastal surface waters from just
beyond the surf zone to 150 km offshore. The movement of
these surface waters can be viewed in near real-time in a Google
Maps interface or at web pages developed for specific users. If
an oil spill occurs, these maps and products can be used to track
where the oil is moving, even at night or in dense fog and
extreme weather. Similar maps and websites allow city
environmental managers to follow the trajectory of coastal
discharges(like sewage spills or coastal runoff after heavy
rains)so that only the affected beaches are targeted for water
safety testing and subsequent closures when needed to protect
our health.
In this paper unlike using pressure based or radar received wave
power analyse which are examples of physical properties of
water wave, the geometrical aspect of surface water wave is
under concentration. So this can be described as a numerical
and mathematical approach which applies on the oceanic water
surface model taken from the altimetry data over a specific area
[6]
