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M. Zribi, M. Parde,
D. Hauser,
P. Fanise,
J. Boutin,
C. Albergel,
J.C. Calvet,
M. Crapeau,
M. Dechambre,
Y. Kerr,
E.L. Baeza,
A. Mialon,
G. Reverdin,
A. Ruis,
K. Saleh,
J.P. Wigneron
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ABSTRACT: The CAROLS, L band radiometer, is built and designed as a copy of EMIRAD II radiometer of DTU team. It is a Correlation radiometer with direct sampling and fully polarimetric (i.e 4 Stockes). It will be used in conjunction with other airborne instruments (in particular the C-Band scatterometer (STORM) and IEEEC GPS system, Infrared CIMEL radiometer and one visible camera), in coordination with in situ field campaigns for SMOS CAL/VAL. The instruments are implemented on board the French research airplane ATR42. A scientific campaign with thirteen flights is realized over south-western France, Valencia site and Bay of Biscay (Atlantic Ocean) in spring 2009. In order to qualify the radiometer data, different types of aircraft movements were realized: circle flights, wing and nose wags. Simultaneously to flights, different ground measurements were made over continental surfaces and ocean. Results show a good quality of data. For continental surfaces, important Radio-Frequency Interferences (RFI) were observed over a large part of the studied region.
Microwave Radiometry and Remote Sensing of the Environment (MicroRad), 2010 11th Specialist Meeting on; 04/2010
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M. Zribi,
D. Hauser, M. Parde,
P. Fanise,
P. Leroy,
M. Dechambre,
J. Boutin,
G. Reverdin,
J.C. Calvet,
A. Weill,
J.P. Wigneron,
N. Skou,
S.S. Sobjaerg,
A. Ruis,
E. Cadareche
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ABSTRACT: The CAROLS, L band radiometer, is built and designed as a copy of EMIRAD II radiometer of DTU team. It is a Correlation radiometer with direct sampling and fully polarimetric (i.e 4 Stockes). It will be used in conjunction with other airborne instruments (in particular the C-Band scatterometer (STORM) and IEEC GPS system, Infrared CIMEL radiometer, one visible camera), in coordination with in situ field campaigns for SMOS CAL/VAL. The instruments are implemented on board the French research airplane ATR42. A validation campaign with four flights was made over south west of France, Hourtin Lake and Bay of Biscay (Atlantic Ocean) in September 2007. In order to qualify the radiometer data, different types of aircraft movements were realized: circle flights, wing and nose wags. Simultaneously to flights, different ground measurements were made over continental surfaces and ocean. First results show a good quality of data over ocean surfaces. For continental surfaces, important Radio-Frequency Interferences (RFI) were observed over a large part of the studied region.
Microwave Radiometry and Remote Sensing of the Environment, 2008. MICRORAD 2008; 04/2008
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ABSTRACT: This letter proposes an estimation of microwave transmissivity within the Canadian boreal forest. The aim is to correct the forest effect in snow water equivalent estimation from Special Sensor Microwave Imager and Advanced Microwave Scanning Radiometer microwave measurements. The estimation was carried out using ground-based radiometric measurements, at 19 and 37 GHz, and for both polarizations. The results show that the transmissivity is correlated with the stem volume and is independent of the tree species. For high stem volumes (>100 m<sup>3</sup>/ha), the transmissivity is found to be 0.4 and 0.3 for 19 and 37 GHz, respectively.
IEEE Geoscience and Remote Sensing Letters 05/2005; · 1.56 Impact Factor
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ABSTRACT: A number of studies have shown the feasibility of estimating surface soil moisture from L-band passive microwave measurements. Such measurements should be acquired in the near future by the Soil Moisture and Ocean Salinity (SMOS) mission. The SMOS measurements will be done at many incidence angles and two polarizations. This multiconfiguration capability could be very useful in soil moisture retrieval studies for decoupling between the effects of soil moisture and of the various surface parameters that also influence the surface emission (surface temperature, vegetation attenuation, soil roughness, etc.). The possibility to implement N-parameter (N-P) retrieval methods (where N = 2, 3, 4, ..., corresponds to the number of parameters that are retrieved) was investigated in this study based on experimental datasets acquired over a variety of crop fields. A large number of configurations of the N-P retrievals were studied, using several initializations of the model input parameters that were considered to be fixed or free. The best general configuration using no ancillary information (same configuration for all datasets) provided an rms error of about 0.059 m<sup>3</sup>/m<sup>3</sup> in the soil moisture retrievals. If a priori information was available on soil roughness and at least one vegetation model parameter, the rms error decreased to 0.049 m<sup>3</sup>/m<sup>3</sup>. Using specific retrieval configurations for each dataset, the rms error was generally lower than 0.04 m<sup>3</sup>/m<sup>3</sup>.
IEEE Transactions on Geoscience and Remote Sensing 07/2004; · 2.89 Impact Factor
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ABSTRACT: To retrieve soil moisture over vegetation-covered areas from microwave radiometry, it is necessary to account for vegetation effects. At L-band, many retrieval approaches are based on a simple model that relies on two vegetation parameters: the optical depth (τ) and the single-scattering albedo (ω). When the retrievals are based on multiconfiguration measurements, it is necessary to take into account the dependence of τ and ω on the system configuration, in terms of incidence angle and polarization. In this paper, this dependence was investigated for several crop types (corn, soybean, wheat, grass, and alfalfa) based on L-band experimental datasets. The results should be useful for developing more accurate forward modeling and retrieval methods over mixed pixels including a variety of vegetation types.
IEEE Transactions on Geoscience and Remote Sensing 03/2004; · 2.89 Impact Factor
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Geoscience and Remote Sensing Symposium, 2003. IGARSS '03. Proceedings. 2003 IEEE International; 08/2003
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ABSTRACT: The objective of this work is to evaluate soil moisture retrieval methods over different canopy, with the view of developing an operational algorithm (for the SMOS project for instance). We tested different inversion process of the τ-ω model, using or not using ancillary information, to estimate soil moisture and τ-ω parameters (vegetation parameters and soil roughness) simultaneously under different crop types. The best general method (same for all data sets) provides a RMSE=0.059 m<sup>3</sup>/ m<sup>3</sup> using no ancillary information and a RMSE=0.048 m<sup>3</sup>/ m<sup>3</sup> if we use soil and vegetation a priori information. Moreover, using specific methods to each data set provide RMSE values between 0.04 and 0.05m<sup>3</sup>/ m<sup>3</sup>.
Geoscience and Remote Sensing Symposium, 2003. IGARSS '03. Proceedings. 2003 IEEE International; 08/2003
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ABSTRACT: A model, coupling the STICS crop growth model, the ISBA SVAT model
and radiative transfer models in various spectral domains, is used for
simulating remote sensing signals at the same time as crop canopy
processes. It is shown that remote sensing data are very sensitive to
initial water content, mainly because of variations in vegetation
growth. When compared to measurements, the coupled model works quite
well. Then, it may be proposed for assimilating remote sensing data with
the objective of monitoring canopy processes
Geoscience and Remote Sensing Symposium, 2001. IGARSS '01. IEEE 2001 International; 02/2001
