POSTERS
Analysis of Scattered Wave from Burnt Coal Pit and Its Application in Estimation Fire Scars Thickness in Central Borneo using JERS-1 SAR Image
Josaphat Tetuko Sri Sumantyo, Ryutaro Tateishi, and Nobuo Takeuchi
Center for Environmental Remote Sensing (CEReS), Chiba University
1-33, Yayoi, Inage, Chiba, Chiba 263-8522, Japan, Email :
In 1995, the Indonesian Government released peat land in central Borneo to be converted into agricultural land. It was known as ‘one-million peat land project’. The project composed of four areas called Peat Land Project (PLG) - A to D. This study chose PLG-A (114.4-114.75 E, 2.4-2.75 S) as the study area. The ground data of the study area were collected in the period 1995-1997 to build database of distribution of coal pit thickness. In this project, vegetation was burnt to open up the area. These fire events caused coal pit fires that were difficult to extinguish. The effects were inferred from SPOT HRV images acquired on 6 June 1997 (prior fire), 29 July 1997 and 8 September 1997 (during fire), and 7 August 1997 (after fire). It was important to investigate the thickness of burnt coal pit in order to protect the spreading of fire and to detect the fire spots in efficient and in early stage. In this study, JERS-1 SAR image acquired on 29 July 1997, during the fires, was used to estimate the thickness of burnt coal pit of the study area. Analysis of scattered waves from burnt coal pit is conducted in order to estimate thickness of the pit. The model is composed of three media namely; free space, burnt coal pit, and peat land. For computation purposes, the equivalent circuit of this model is conducted using transmission line circuit. The relationship between the backscattering coefficient and the burnt coal pit thickness are defined by power logarithm of the coefficient of reflection. The analysis result is confirmed by a two-dimensional (2-D) finite-difference model for scattered waves from the burnt coal pit. The model uses the equation of scattered electromagnetic fields that was derived from Maxwell’s equations. These fields are discretized using center finite-difference. Mur method is used to surround the discretized solution space and absorb the outward traveling waves. The analysis and the simulation results are in good agreement. Subsequently, the developed model is applied to estimate the burnt coal pit thickness in central Borneo fire events using Japanese Earth Resources Satellite (JERS-1) SAR image. Results agree with ground measurements.
Low Frequency (5MHz) SAR Imagery and InSAR Analysis of Lunar Radar Sounder
in SELENE Project
Takao Kobayashi (1), Takayuki Ono (1), and Hiroshi Oya (2)
(1) Geophysical Institute, Tohoku University
Aramaki Aza Aoba, Aoba, Sendai 980-0845 Japan, Email :
(2) : Department of Engineering, Fukui Institute of Technology
Fukui, JAPAN
Spaceborne Low Frequency (5 MHz) radar sounder observation has been numerically simulated in order to estimate the performance of Lunar Radar Sounder (LRS) of the SELENE project.
SELENE is a lunar exploration project which is planned to be launched in 2004 and LRS is one of its 14 onboard missions. The primary objective of LRS is exploration of lunar subsurface structure. LRS is an FMCW radar whose frequency in HF band is linearly swept from 4 MHz to 6 MHz in 200 μsec and is facilitated with a crossed pair of dipole antennas that are tip-to-tip 30m long. Using either antenna, LRS detects nadir subsurface echoes. SAR analysis method was adopted in LRS data analysis procedure so as to discern nadir subsurface echoes from off nadir surface echoes which are reflected from complex lunar surface terrains of imapact craters.
The simulation code has been newly developed from scratch. It treats the whole sequence of LRS observation; from transmission of HF pulse to analysis of observation data as well as numerically creating cratered terrain of lunar surface. The core program of the code that calculates surface reflection/refraction has been designed based on Kirchhoff theory.
Simulation results show that both SAR imagery and InSAR analysis of LRS are well practical in spite of using a simple dipole antenna : LRS SAR is capable of recognizing craters as small as of the order of 100m in diameter while LRS InSAR determines the elevation distribution of surface terrain with the standard deviation of error being no larger than twice as much as the wave length of LRS pulse. The mirror image ambiguity which is inherent to dipole SARs is eliminated by taking multi look correlation of SAR images. In the same manner, the mirror image problem in InSAR analysis is resolved.
These results imply that LRS SAR imagery can provide crater population information of lunar surface which is important in determining chronology of lunar surface evolution. They also imply that LRS InSAR is able to visualize subsurface terrain if off nadir subsurface reflection is strong enough to dominate surface back scattering: such condition could occur in mare regions where surface terrain is much less rough than high land (cratered terrain) region.
We believe those SAR and inSAR analysis methodology for LRS can be applied to future planetary missions, and that, thanks to the simple design, a low frequency radar with a dipole antenna will be a powerful tool of planetary exploration in obtaining both surface and subsurface information of terrestrial bodies.
Definition of the CONSERT / ROSETTA Radar Performances
Alain Herique and Wlodek Kofman
Laboratoire de Planetologie de Grenoble, Universite Joseph Fourier
Batiment de Physique D - BP 53, 38041 Grenoble Cedex 9, France, Email :
The ROSETTA/ESA probe will rendezvous Comet Wirtanen in 2011 and launch a Lander at the nucleus surface. The CONSERT instrument will perform the sounding of the comet nucleus by measuring a 90 MHz electromagnetic wave propagation from the Lander to the orbiter throughout the nucleus. The goal of this sounding is to determine the internal structures of the comet nucleus at different scales and to deduce information on its composition (density, type and abundance of the refractor) [1], [2]. The flight model of both Lander and Orbiter parts of the instrument are in integration and calibration phases.
The CONSERT instrument is an original concept of spaceborne radar based on the propagation throughout the nucleus while the classical radars are based on the reflection. This radar consists in three functions:
* A chronometer to measure the propagation delay (main function)
* An imager to separate the multipath propagation
* A radiometer to estimate the wave attenuation (secondary function)
The ground calibration of the instrument has to characterize these three functions but due to the novelty of the instrument concept we have no classical set of parameters to quantify the instrument performances and we do not know the relevant performances from a data-inversion point of view.
In this paper, we present the mission and its objectives and so we develop the method used to define a relevant set of instrument performances using the data of prototypes of the instrument and we compare our radar characterization with the SAR instrument performances. In particular, we study the accuracy and the stability of the delay measurement and of the power measurement.
In a second time we propose a ground calibration plan. The instrument design and the absence of calibration channel due to mass and power constraints show technical limitation and require specific signal processing and calibration protocol.
To end we show preliminary results of the instrument ground calibration.
[1] Kofman W., et al., Comet Nucleus Sounding Experiment by Radiowave Transmission. Advances in Space Research, 1998, Vol 21, No. 11, pp 1589-1598.
[2] Herique A., et al., A statistical characterization of comet nucleus: Inversion of simulated radio frequency data, Planetary and Space Sciences, 1999, Vol 47, No. 6, pp 885-904.
Review of the Application of Spaceborne P-band SAR Radar : Slant and Vertical Configuration
Alain Herique (1), Monique Dechambre (2), Frederique Remy (3), Pierre Bauer (3), Bertrand Chapron (4), Woldek Kofman (1), Jean Lilensten (1), and Philippe Paillou (5)
(1) Laboratoire de Planetologie de Grenoble , Universite Joseph Fourier
Batiment de Physique D - BP 53, 38041 Grenoble Cedex 9, France, Email :
(2) CETP / IPSL
10-12, avenue de l'Europe 78140 Velizy, Paris, France, Email :
(3) LEGOS
18, av. Edouard Belin, 31401 Toulouse Cedex 4, France, Email :
(4) IFREMER
Technopole de Brest-Iroise, BP 70, 29280 Plouzane, FRANCE
(5) Observatoire de Bordeaux
2 Rue de l'Observatorire, Bp 89, 33270 Floirac, FRANCE
Email :
The P-Band appears as a major opportunity in spaceborne SAR domain. The capability of the larger wavelength to penetrate the material media gives information on the surface and the near sub-surface of the Earth. A P-Band spaceborne radar instrument would be complementary to existing and forthcoming spaceborne optical and radar observations which are limited to observations of superficial surfaces. Major scientific results are expected in the whole Earth Observation community:
* glaciology for the 3D cartography of the Antarctic ice sheet including bedrock and internal layer topography
* vegetation due to a larger sensitivity of the high biomass (200 ton/ha)
* soil geophysics and hydrology with the detection of water tables, the monitoring of the water contents
* oceanography application based on a lower sensitivity to the air/sea interface roughness effects
* aeronomy to monitor the Total Electron Contents of the ionosphere.
A part of the above scientific objectives were validated using Ground Penetrating Radar measurement, ground facilities or airborne radar.
Various concepts of measurement are identified:
* The slant looking configuration is the classical SAR concept working in pulse limited radar mode.
* The nadir looking configuration is a new radar mode for Earth Observation using SAR synthesis associated to an altimeter geometry. The analysis of the physics of the measurement shows its originality for low frequency. The signal is a mixture of deep echoes and surface echoes and the signal of interest depends on the geophysical application which determines the radar mode.
In this paper we analyzed the scientific objectives of the P-Band including the original contribution of the P-Band and the maturity of this application.
In a second step the concepts of both instruments are reviewed. The concept applicability is analyzed for each scientific application and preliminary specifications are deduced.
Ionospheric Propagation for Low Frequency Spaceborne Radar Sounding : Modeling and Correction
Jean Francois Nouvel (1), Alain Herique (1), Wlodek Kofman (1), and Olivier Witasse (2)
(1) Laboratoire de Planetologie de Grenoble , Universite Joseph Fourier
Batiment de Physique D - BP 53, 38041 Grenoble Cedex 9, France, Email :
(2) Solor System Division, ESTEC / ESA
PB 299, 2200 AG Noordwijk, The Netherlands
Several spaceborne ground penetrating radars have been proposed in the past ten years for various Earth and planetary observation missions: Mimosa for Antarctic survey, Marsis and Surprise for Martian permafrost characterization,… These instruments are based on a nadir looking synthetic aperture radar operating at low frequency which allows to penetrate the ground without too large dielectric losses. The received signal is then a mixture of deep echoes and surface echoes. The instrument and the processing are designed to maximize the coherent power to clutter ratio.
The analysis of the wave propagation shows that the wave propagation throughout the ionosphere induces major distortions which consist in pulse-to-pulse phase coherence loss, pulse spreading and attenuation. The impact of each phenomenon depends on the frequency and on the ionospheric electronic contents. They can significantly reduce the signal resolution and the penetration capabilities.
In this paper, we analyze the induced pulse distortions for MARSIS radar: the pulse spreading and attenuation are studied for various models of ionosphere. In a second time we present different methods of pulse compression based on the data itself: the radar signal is used to estimate the ionospheric distortions which are thus compensated. These methods are applied on data simulated by surface integrals.
Operational Coastal Map Reactualization by RADAR SAR ERS Images, Examples French Guiana, in the Area of Nouakchott City in Mauritania and Douala, Cameroon
Herve Trebossen (1), Jean-Paul Rudant (2), Nicolas Classeau (2), Benedicte Fruneau (2), MF. Courel (3), Joseph Mvogo (2), Vincent de Paul Onana (2), and Emannuel Tonye (4)
(1) IFG, UMLV/SHOM
5 Bd Descartes, Marne La Vallee, 77454 Cedex 2, France, E-mail :
(2) UMLV
5 Bd Descartes, Marne La Vallee, 77454 Cedex 2, France, Email :
(3) CNRS/PRODIG
191, rue Saint-Jacques - 75 005 Paris, France, Email :
(4) ENSP
653, rue 3386 B.P 8390 Yaounde, Cameroun, E-mail :
French Hydrographic Office has to publish informations for navigation security in its responsible zones (French territories, West African Coasts (with agreements between these countries and France), Djibouti, Viet-Nam, and so on...). Nautical charts on african coasts are old and had often been established in the fifties. Local geodetic reference systems used are not well known, so maps are not in accordance for GPS navigation. In French Guiana, coastal evolutions are so important that nautical charts are obsolets. Sedimentation and erosion of mangrovia vegetation can reach one kilometer per year. Goals of our communication is to study contribution of RADAR SAR imagery for nautical charts updates. Our interests are coastline, interidal zone delimitation, harbour's structures and bathymetry (< 20 meters).
We will present in this communication solutions we have retained for different problems :
Fisrt, For cartographic applications, we reference geographically our ERS images in a global geodetic reference system without ground points, we used precise orbitographic products, high difference between geoid and global ellipsoid and ERS annotations files : precision estimation of this step was made by GPS measurements and also comparison between images acquired in ascending and descending mode.
Second, ground interpretation permit first in Mauritania and french Guiana to follow coastal evolution and particularly coastline erosion and flood risk zones, and last in Cameroon to understand high and low vegetation distribution in mangrovia and in Wouri estuary, to follow sand banks which obstruct Douala city channel. We propose a methodology for ERS RADAR SAR use including interferometry and speckle reduction process.
Third, we will present new coastal cartographic documents for regions with strong changes and a low map update frequency.
The Extended Exact Transfer Function SAR Processing Algorithm
Tove Tennvassaas, Ole Morten Olsen, and Gunnar Rasmussen
Research and Development, Kongsberg Spacetec AS
Prestvannveien 38, N-9292, Tromsoe, Norway, Email :
A fast phase preserving Synthetic Aperture Radar processing algorithm tailored for spaceborne SAR has been developed by the Norwegian Defence Research Establishment (NDRE). The algorithm is based on calculating the point target response in the frequency domain (the Exact Transfer Function or ETF). The second and fourth order ETF and new phase correction functions have been calculated. ETF with phase corrections is called Extended Exact Transfer Function (Extended ETF or EETF).