ASTER data processing and fusion for alteration minerals and silicification detection:Implications for cupriferous mineralization exploration in the western Anti-Atlas,Morocco

Alteration minerals and silicification are typically associated with a variety of ore mineralizations and could be detected using multispectral remote sensing sensors as indicators for mineral exploration.In this investigation,the Visible Near-Infra-Red(VNIR),Short-Wave Infra-Red(SWIR),and Thermal Infra-Red(TIR)bands of the ASTER satellite sensor derived layers were fused to detect alteration minerals and silicification in east the Kerdous inlier for cupriferous mineralization exploration.Several image processing techniques were executed in the present investigation,namely,Band Ratio(BR),Selective Principal Component Analysis(SPCA)and Constrained Energy Minimization(CEM)techniques.Initially,the BR and SPCA processing results revealed several alteration zones,including argillic,phyllic,dolomitization and silicification as well as iron oxides and hydroxides.Then,these zones were mapped at sub-pixel level using the CEM technique.Pyrophyllite,kaolinite,dolomite,illite,muscovite,montmorillonite,topaz and hematite were revealed displaying a significant distribution in relation with the eastern Amlen region lithological units and previously detected mineral potential zones using HyMap imaging spectroscopy.Mainly,a close spatial association between iron oxides and hydroxide minerals,argillic,and phyllic alteration was detected,as well as a strong silicification was detected around doleritic dykes unit in Jbel Lkest area.A weighted overlay approach was used in the integration of hydrothermal alteration minerals and silicification,which allowed the elaboration of a new mineral alteration map of study area with five alteration intensities.ASTER and the various employed processing techniques allowed a practical and cost effective mapping of alteration features,which corroborates well with field survey and X-ray diffraction analysis.Therefore,ASTER data and the employed processing techniques offers a practical approach for mineral prospection in comparable settings.

Mesoscale surface circulation and variability of Southern Indian Ocean derived by combining satellite altimetry and drifter observations

High resoultion Eulerian mean velocity field has been derived by combining the satellite tracked surface drifter data with satellite altimetry and ocean surface winds. The drifter data used in this study includes Argos and surface drifter data from Global Drifter Program. Maps of Sea Level Anomaly （MSLA） weekly files with a resolution of （1/3）° in both Latitude and Longitude for the period 1993-2012 have been used. The Ekman current is computed using ocean surface mean wind fields from scatterometers onboard ERS 1/2, Quikscat and ASCAT. The derived mean velocity field exhibits the broad flow of Antarctic Circumpolar Current with speeds up to 0.6 m/s. Anomalous field is quite significant in the western part between 20~ and 40~E and in the eastern part between 80~E and 100~E with velocity anomaly up to 0.3 m/s. The estimated mean flow pattern well agrees with the dynamic topography derived from in-situ observations. Also, the derived velocity field is consistent with the in-situ ADCP current measurements. Eddy kinetic energy illustrates an increasing trend during 1993-2008 and is in phase coherence with the Southern Annular Mode by three month lag. Periodic modulations are found in the eddy kinetic energy due the low frequency Antarctic Circumpolar Wave propagation.

3-D visualizations of coastal bathymetry by utilization of airborne TOPSAR polarized data

Multi-frequency C and L bands in the TOPSAR data have been utilized to reconstruct three-dimensional(3-D)bathymetry pattern.The main objective of this study is to utilize fuzzy arithmetic to reduce the errors arising from speckle in synthetic aperture radar(SAR)data when constructing ocean bathymetry from polarized SAR data.In doing so,two 3-D surface models,the Volterra algorithm and a fuzzy B-spline(FBS)algorithm,which construct a global topological structure between the data points,were used to support an approximation to the real surface.Volterra algorithm was used to express the non-linearity of TOPSAR data intensity gradient based on the action balance equation(ABC).In this context,a first-order kernel of Volterra algorithm was used to express ABC equation.The inverse of Volterra algorithm then performed to simulate 2-D current velocities from CVV and LHH band.Furthermore,the 2-D continuity equation then used to estimate the water depth.In order to reconstruct 3-D bathymetry pattern,the FBS has been performed to water depth information which was estimated from 2-D continuity equation.The best reconstruction of coastal bathymetry of the test site in Kuala Terengganu,Malaysia,was obtained with polarized L and C bands SAR acquired with HH and VV polarizations,respectively.With 10 m spatial resolution of TOPSAR data,bias of
0.004 m,the standard error mean of 0.023 m,r2 value of 0.95,and 90%confidence intervals in depth determination was obtained with LHH band.

Modeling sprawl of unauthorized development using geospatial technology: case study in Kuantan district, Malaysia

The paper explores a framework combining remote sensing and GIS-cellular automata(CA)concepts aimed at improving the modeling of unauthorized land use sprawl.Remote sensing data have been used in urban modeling and analysis,the use of high-resolution remote sensing data in assessing unauthorized development is quite unexplored.This work has demonstrated systematic combination utilization of geospatial analyses tools to acquire a new level of information to enable urban modeling and sprawl analysis in assisting urban sustainable management.In this study,Kuantan city,Malaysia was selected in simulation of the unauthorized land use with CA concept for a period of 15 years(2000
2015),with main input time-series land use observation from 1995 to 2005.The 2000 and 2005 land use input was also used as calibrated and test assessment of the simulation.The results show excellent agreement between in-situ changes of the unauthorized land use classes and the corresponding simulated classes within the same periods.In conclusion,CA model can lead to new levels of understanding of how urban areas grow and change as in view of digital earth aspiration.