Comparison of atmospheric correction methods using ASTER data for the area of Crete, Greece

2010 ◽  
Vol 31 (24) ◽  
pp. 6347-6385 ◽  
Author(s):  
Nektarios Chrysoulakis ◽  
Michael Abrams ◽  
Haralambos Feidas ◽  
Korei Arai
2010 ◽  
Vol 27 (10) ◽  
pp. 1677-1688 ◽  
Author(s):  
África Barreto ◽  
Manuel Arbelo ◽  
Pedro A. Hernández-Leal ◽  
Laia Núñez-Casillas ◽  
María Mira ◽  
...  

Abstract The land surface temperature (LST) and emissivity (LSE) derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were evaluated in a low spectral contrast volcanic site at an altitude of 2000 m on the island of Tenerife, Spain. The test site is almost flat, thermally homogeneous, and without vegetation cover or variation in its surface composition. ASTER data correspond to six scenes, under both day- and nighttime conditions during 2008. This case study analyzes the impacts of the sources of inaccuracies using the temperature–emissivity separation (TES) algorithm. Uncertainties associated with inaccurate atmospheric correction were minimized by means of local soundings and the climate advantages of the area. Concurrent ground-based radiometric measurements were performed for LST, and laboratory and field measurements for LSE, to obtain reference values. The TES evaluation showed a good level of agreement in the emissivity derived for ASTER bands 13 and 14 [root-mean-square difference (RMSD) lower than 0.002] and discrepancies in ASTER bands 10 and 11 that were within the expected performance of the algorithm (±0.015). However, out-of-threshold errors were retrieved in band 12, producing an artificial increase in spectral contrast. The underestimated TES LSE spectra point to the presence of a roughness effect at measurement scales that may increase the laboratory band emissivity values. TES LST comparison with ground data showed an RMSD value of 0.5 K. ASTER standard products AST08 (LST) and AST05 (LSE) atmospherically corrected by means of Naval Research Laboratory (NRL) data were also tested, showing a similar level of performance for the TES implemented with local soundings, but failed in high-humidity atmospheric conditions.


Author(s):  
El Zalaky , Abdelmonsif

   The younger granite of El-Erediya pluton represents one of the most important prospect areas in the Egyptian Central Eastern Desert which comprise surface and subsurface U-mineralization confined to the southern part of the pluton. Due to the high uranium airborne anomaly of the northern part than the southern part of the pluton, the granite of northern part need to reevaluate its U-potentiality according to the modern techniques that were developed in the last decade.      The main goal of this paper is to examine the efficiency of the Advanced Space-borne Thermal Emission and Reflectance Radiometer (ASTER) data in mapping the alteration zones that could be host uranium mineralization within the younger granite of El-Erediya pluton using spectral analysis techniques.      ASTER data are especially attractive to many geological researchers in Africa, due to their open availability and associated minimal costs for academic use. The three visible and six near-infrared bands, which have 15-m and 30-m resolution, respectively, were calibrated by using atmospheric correction.      Target detection using spectral-matching algorithm was applied to recognize the most predominant alteration components such as hematite, kaolinte, illite and alunite as more or less considered as path finder of uranium mineralization to trace the most promising zones affected by these alteration within the granite of El Erediya pluton.      Three ASTER-derived promising areas have been detected, including the prospect area, using the matched filtering methods with a confidence ranging from 68 to 95%. All of these zones that delineated by target detection technique show good correlation with those on field and on the reference geologic map.      Two of these target zones are proved in the field and founded along the structural features cutting the northern parts of El Erediya pluton that have not been identified before. Mineralogical studies were carried out, using ore and scanning microscope and XRD, for some selective mineralized samples collected form one of these tow target zones. These investigations confirm the presence of uranophane mineral as uranyl silicates in addition to zircon and fluorite. These minerals are found in close association with hematitization, kaolinitization, and illitization alteration.  


2015 ◽  
Vol 8 (3) ◽  
pp. 1593-1604 ◽  
Author(s):  
C. Bassani ◽  
C. Manzo ◽  
F. Braga ◽  
M. Bresciani ◽  
C. Giardino ◽  
...  

Abstract. Hyperspectral imaging provides quantitative remote sensing of ocean colour by the high spectral resolution of the water features. The HICO™ (Hyperspectral Imager for the Coastal Ocean) is suitable for coastal studies and monitoring. The accurate retrieval of hyperspectral water-leaving reflectance from HICO™ data is still a challenge. The aim of this work is to retrieve the water-leaving reflectance from HICO™ data with a physically based algorithm, using the local microphysical properties of the aerosol in order to overcome the limitations of the standard aerosol types commonly used in atmospheric correction processing. The water-leaving reflectance was obtained using the HICO@CRI (HICO ATmospherically Corrected Reflectance Imagery) atmospheric correction algorithm by adapting the vector version of the Second Simulation of a Satellite Signal in the Solar Spectrum (6SV) radiative transfer code. The HICO@CRI algorithm was applied on to six HICO™ images acquired in the northern Mediterranean basin, using the microphysical properties measured by the Acqua Alta Oceanographic Tower (AAOT) AERONET site. The HICO@CRI results obtained with AERONET products were validated with in situ measurements showing an accuracy expressed by r2 = 0.98. Additional runs of HICO@CRI on the six images were performed using maritime, continental and urban standard aerosol types to perform the accuracy assessment when standard aerosol types implemented in 6SV are used. The results highlight that the microphysical properties of the aerosol improve the accuracy of the atmospheric correction compared to standard aerosol types. The normalized root mean square (NRMSE) and the similar spectral value (SSV) of the water-leaving reflectance show reduced accuracy in atmospheric correction results when there is an increase in aerosol loading. This is mainly when the standard aerosol type used is characterized with different optical properties compared to the local aerosol. The results suggest that if a water quality analysis is needed the microphysical properties of the aerosol need to be taken into consideration in the atmospheric correction of hyperspectral data over coastal environments, because aerosols influence the accuracy of the retrieved water-leaving reflectance.


Sign in / Sign up

Export Citation Format

Share Document