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P. Ferrazzoli,
R. Rahmoune,
F. Moccia,
F. Grings,
M. Salvia,
M. Barber,
V. Douna,
H. Karszenbaum,
A. Soldano,
D. Goniadzki,
G. Parmuchi,
C. Montenegro, P. Kandus,
M. Borro
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ABSTRACT: The objective of this paper is to describe and explain the effects on selected AMSR-E channels of two strong events, i.e., a rainstorm and a flooding, occurred in the Argentine section of La Plata basin. More specifically, the rainstorm took place within the Chaco region, which is covered by a continuous, moderately dense forest. The flooding affected the terminal part of Parana¿ River. The study is based on monitoring the temporal trends of the polarization indexes at various AMSR-E bands. In the forest, the rainstorm produces an effect on C band channels which is moderate, but well evident. The presence of this effect agrees with model simulations presented in previous papers. In the Parana¿ River, measurements of water level are available. Variations of polarization index at various frequencies are observed in correspondence with variations of water level in four different stations. However, the amount of the effect and the correlation between variables are dependent on the properties of the areas surrounding the stations. The Delta of Parana¿ river, where a land cover map is available, was selected for estimation of fraction of flooded area by using an algorithm available in the literature.
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 04/2010; · 1.49 Impact Factor
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ABSTRACT: This paper analyses the SAR response of wetland ecosystems under different environmental conditions and at two different frequencies. We exploited the opportunity of observing the same inundation phenomena by two currently available SAR systems, such as ENVISAT ASAR (C band) and ALOS PALSAR (L band). The results obtained for C band are similar to the ones reported previously in the same area. Increasing water level in marshes is characterized by an increase and then a decrease in the backscattering coefficient of vegetation. An increase when water level changes the soil from saturated to flooded condition and a decrease when the water covers the vegetation. The new ALOS PALSAR L band results shows that in marshes, the increase in water level is seen as a decrease in the backscattering coefficient, since the reduction of emerged biomass reduces the available matter for the wave to interact with.
Geoscience and Remote Sensing Symposium, 2008. IGARSS 2008. IEEE International; 08/2008
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ABSTRACT: This paper focuses on the use of radar remote sensing for water storage estimation in wetland marshes of the Paraná River Delta in Argentina. The approach followed is based on the analysis of a temporal set of ENVISAT ASAR data which includes images acquired under different polarizations and incidence angles as well as different environmental conditions (water level, precipitation, and vegetation condition). Two marsh species, named junco and cortadera, were monitored. This overall data set gave us the possibility of studying and understanding the basic interactions between the radar, the soil under different flood conditions, and the vegetation structure. The comprehension of the observed features was addressed through electromagnetic models developed for these ecosystems. The procedure used in this work to estimate water level within marshes combines a direct electromagnetic model, field work data specifically obtained to feed the model, the actual ASAR measurements and a well known retrieval scheme based on a cost function. Results are validated with water level evaluations at specific points. A map showing an estimation of the water storage capacity and its error in junco and cortadera areas for the date where the investigation was done is also presented.
Journal of Environmental Management 04/2008; 90(7):2189-98. · 3.24 Impact Factor
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ABSTRACT: This paper discusses the contribution of multipolarization radar data in monitoring flooding events in wetland areas of the Delta of the Parana´ River, in Argentina. The discussion is based on the comparison between radiative transfer model simulations and ENVISAT Advanced Synthetic Aperture Radar observations of two types of marshes: junco and cortadera. When these marshes are flooded, the radar response changes significantly. The differences in radar response between the flooded and nonflooded condition can be related to changes in the amount of emerged biomass. Based on this, we propose a vegetation-dependent flooding prediction scheme for two marsh structures: nearly vertical cylinders (junco-like) and randomly oriented discs (cortadera-like).
IEEE Transactions on Geoscience and Remote Sensing 05/2006; · 2.89 Impact Factor
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ABSTRACT: In this work, multitemporal synthetic aperture radar (SAR) data in conjunction with an electromagnetic (EM) model and a vegetation growth model were used to monitor and explain burn-regrowth events of junco vegetation in a wetland environment. The data used were from Radarsat-1, ENVISAT Advanced Synthetic Aperture Radar (ASAR), and European Remote Sensing 2 (ERS-2) temporal series. The EM model is based on radiative transfer theory and describes junco vegetation as a set of vertical dielectric cylinders on a flat flooded surface. It was used, together with the vegetation growth model, to predict the temporal evolution of the radar response during a burn-regrowth event. This simulation was compared with the ERS-2 vertical (VV) data. It was observed a "bell-shaped" temporal trend that was confirmed by the simulated data with a mean error of 2.5 dB. Additionally, in view of current and future ENVISAT ASAR Alternating Polarization Mode Precision data, the horizontal (HH) SAR temporal response was also simulated giving as a result strong differences between simulated HH and VV temporal trends. These differences are in good agreement with the ones observed between Radarsat-1 HH and ERS-2 VV SAR data acquired at close dates and also with the same differences observed between HH and VV ENVISAT ASAR data. Electromagnetic modeling results provide a sound theoretical interpretation of these observations.
IEEE Transactions on Geoscience and Remote Sensing 11/2005; · 2.89 Impact Factor
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ABSTRACT: During the period 1999-2000 frequent fires occurred in the delta of Parana´ River, Buenos Aires, Argentina. A set of 13 ERS 2 images were collected within the frame of the ESA AO3 232 project. One of the basic concerns when trying to make use of these data for time series analysis is the need of tools for calibration of the SAR data, image coregistration, reduction of the radiometric uncertainty, and creation of the specific change detection algorithm. This paper presents the efforts made toward setting a processing procedure for these tasks. It combines ESA SARtoolbox with software developed within the ENVI-IDL environment that includes image coregistration, a temporal filter for increasing the number of looks but avoiding a loss in spatial resolution, and a change detection algorithm that maps the observed increase-decrease in the SAR response due to fires in this area.
Geoscience and Remote Sensing Symposium, 2003. IGARSS '03. Proceedings. 2003 IEEE International; 08/2003
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ABSTRACT: The Lower Delta Islands of the Paran River in Argentina constitute a major coastal tidal freshwater wetland located at the De La Plata River estuary, very close to Buenos Aires City. It is a complex region where the landscape pattern is characterized by mosaics of natural and man made ecosystems. Since the last few years an increased number of SAR images have been available for monitoring coastal areas, offering the possibility of analyzing the microwavevegetation -water-interaction mechanisms that are taking place. This study was conducted to assess the potential of combined imagery from RADARSAT (C-band, HH polarization) and ERS 2 (C-band, VV polarization) SAR systems for monitoring wetland ecosystems and assess flood condition. The SAR response from RADARSAT, and ERS 2 systems, for three distinct vegetation types (forest, marshes, and rushes) under different flood conditions is analyzed. For this task, SAR images were first carefully calibrated and geolocated. To establish hypothesis about the links between land cover structure, flood condition, sensor characteristics (C HH, C VV) and resulting scattering process the information extraction procedure consisted of the multitemporal analysis of the backscattering characteristics of well identified samples. The results show that C VV response is capable of detecting changes due to flood conditions within marshes, and rushes, but not within forest areas. On the other hand, C HH backscatter in forest changes strongly from normal to flooded conditions, but marshes have a similar response. A flood map for the event of el Nio 1998 based on change detection procedures is presented. The strong differences in SAR response between both satellite systems give a clear indication of the potentialities of future ASAR Envisat data for...
12/2001;
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ABSTRACT: Using remote sensing, natural occurring vegetation data can be
gathered and processed for planning purposes and environmental impact
assessments. In contrast to agricultural crops, natural vegetation
communities are present in the form of heterogeneous mosaics with fuzzy
limits. This is observed in the delta of Parana's river, a major fresh
water wetland, located very close to Buenos Aires city, characterized by
a hydrologic regime determined mainly by the lunar and wind tides of De
La Plata River waters, and the Parana and Uruguay river regimes. Natural
vegetation communities coexist with forest plantations, and recreational
areas. This paper presents the procedures used for the study of this
region using satellite remote sensing data (optical and radar). With
respect to optical data, a conceptual classification scheme based on the
flooding regime, human intervention and the structural and fluoristics
characteristics of vegetation was developed. Next a sequential masking
unsupervised classification procedure was applied to a multitemporal
data set to be able to link “information classes” with
“spectral classes” to obtain a land cover map. With respect
to radar data, the conceptual classification scheme was slightly
modified to underline the structural characteristics of vegetation. The
overall objective was to establish the interaction mechanisms between
the different landscape elements of the delta and the SAR system as a
function of sensor parameters and scene characteristics. Backscatter
profiles for different angles of incidence and for different times were
obtained, and discussed
Geoscience and Remote Sensing Symposium Proceedings, 1998. IGARSS '98. 1998 IEEE International; 08/1998
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ABSTRACT: The paper describes how ASAR observations and electromagnetic models were used to obtain estimates of water level below two marshes with different vegetations structure in the Paraná River Delta in Argentina. The approach followed is based on the analysis of a temporal set of ENVISAT ASAR data which includes images acquired under different polarizations and incidence angles as well as different environmental conditions (water level, precipitation, and vegetation condition). Two marsh species, named Junco and Cortadera, were monitored. The comprehension of the observed backscattering features was addressed through electromagnetic models developed for these ecosystems. Results are validated with water level evaluations at specific points. A map showing estimated water levels below Junco and Cortadera areas, is presented.
