numerical models for planning landslide risk mitigation strategies in iconic but unstable landscapes the case of cinque torri dolomites italy abstract this study deals with the numerical modelling of large deep seated instability processes affecting the cinque torri group dolomites italy which is a unesco world heritage site the aim is to evaluate the role of intrinsic causal factors and to assess the failure mechanism proposed in previous investigations the geological model is based on topographic geological and geomechanical surveys complemented with mineralogical physical and geotechnical lab analyses for parameters determination the numerical simulations have been carried out using a distinct element method code on conceptual and site specific slope models a series of parametric analyses have been performed to characterize the role of the different predisposing factors potentially related with the ongoing rock spreading i load of the rocky pinnacles ii lithology stratigraphy and attitude of the geological units iii discontinuity sets in the rock mass iv degradation of the mechanical properties the results of this study suggest that the shear zone initiation is controlled by stress concentration due to the loading of the dolomitic pinnacles whereas its shape appears to be structurally controlled by the dip slope attitude of bedding in clay rich mudstones the interpretation of the modelling results has provided a better understanding of the ongoing deformation process which can help in targeting effective and low impact landslide risk mitigation strategies in this iconic landscape

latitudinal structure and extension of the polar atmospheric disturbance the dissipation of solar wind energy in the upper atmosphere generates a disturbance whose morphology depends on local time season and magnetic activity a statistical analysis of esro 4 data reveals that 1 in the afternoon evening sector the disturbance boundary coincides with the region of electric current dissipation along the auroral oval 2 in the midnight early morning sector dynamical effects extend the disturbance zone to lower latitudes and this expansion is strongly dependent on season and magnetic activity and 3 in the late morning sector direct heating effects along the auroral oval are superimposed on the residuals of the early morning disturbance these results are consistent with previous observations and provide new boundary conditions for upper atmospheric models

auroral zone thermospheric dynamics 2 individual nights ground based fabry perot spectrometer measurements of the o i 15867 k 630 0 nm 1 k 1 cm 1 emission line were obtained from college alaska during the winters of 1981 to 1983 averages of the temperatures and winds derived from these measurements show a general flow driven by ion drag due to magnetospheric convection this hypothesis was supported by results from a global thermospheric circulation model individual nights however show differences from the average flow pattern during the recovery phase of an auroral substorm when the westward electrojet is over the observing site the equatorward meridional wind decreases in magnitude the zonal wind is generally westward in the evening and eastward in the morning however the crossover from westward to eastward flow is a function of the location of the substorm onset and the arrival of the westward electrojet over college zenith winds can be very large 200 m s and show no systematic pattern perhaps due to a superposition of wave modes from the auroral zone source region an example of a night with little auroral activity highlights the effects of magnetospheric convection and the auroral electrojet on the normal auroral zone wind pattern temperature measurements occasionally show large enhancements usually associated with type a red aurora

thermospheric circulation temperature and compositional structure of the southern hemisphere polar cap during october november 1981 thermospheric temperature composition and winds at f region heights over the southern hemisphere polar cap have been measured by the dynamics explorer 2 de 2 satellite during october november 1981 perigee of the de 2 satellite during this period was over the southern hemisphere polar cap and measurements made along 0900 2100 local time polar passes are used to determine the average universal time dependence of thermospheric properties for this local time slice the f region wind vector is derived from the meridional wind component measured by the fabry perot interferometer fpi and the zonal wind component measured by the wind and temperature spectrometer wats instruments on board de 2 the neutral gas temperature is derived from fpi and wats measurements and the compositional structure is determined from the neutral atmosphere composition spectrometer instrument the measured temperature composition and winds along the 0900 2100 local time polar passes all display a universal time dependence that is due to the displacement between geomagnetic and geographic poles the temperature and molecular nitrogen densities are enhanced and the atomic oxygen density is reduced in the magnetic polar cap in comparison with lower latitude regions the neutral wind pattern follows the pattern of ion drift associated with magnetospheric convection the national center for atmospheric research thermospheric general circulation model tgcm is used to calculate the temperature composition and winds over the southern hemisphere polar cap region for conditions similar to those of october 1981 the tgcm includes displaced geomagnetic poles the temperature composition and winds are determined along the de 2 satellite track for various universal times the calculated winds are in general agreement with the observed winds both having a two cell pattern of magnetospheric convection the calculated and observed composition patterns are also in general agreement with predictions made by the mass spectrometer and incoherent scatter radar 1983 empirical model when models and observations are normalized to the same constant pressure surface the calculated and observed maximum compositional variations in the magnetic polar cap occur near 0900 ut when the dawn sector of the auroral oval passes over the south geographic pole the overall pattern of the calculated temperature variation is similar to that observed except for the period between 1300 and 1500 ut better agreement with temperature in this time range is obtained with the inclusion of auroral particle precipitation within the magnetospheric cusp

mineral mapping and ore prospecting using landsat tm and hyperion data wushitala xinjiang northwestern china abstract the southern tianshan area situated in central asia is one of the most important gold belts identified by many world class superlarge and large gold deposits the wushitala area located in the eastern part of southern tianshan xinjiang china has a strong potential for gold and other metallic mineral deposits however no metallic mineral deposit or occurrence has been reported in detail for the wushitala area in the past apparently due to poor exploration this study attempts to map alteration zones and acquire ore prospecting targets in the wushitala area by integrating landsat tm and hyperion data with the aster spectral library mineral spectra the crosta technique and the anomaly overlaying selection method were combined to process four temporal landsat tm data acquired in the same season in different years so as to eliminate the random interference caused false anomalies of alteration minerals iron oxides and hydroxyl bearing minerals and carbonates while retaining the real anomalies the matched filtering method was applied on hyperion data for the detailed identification of hydrothermally altered minerals surrounding the granites in the north the results of hyperion data are spatially consistent with those of landsat tm data furthermore the results of hyperion data show that the alteration minerals associated with the potash feldspar granite are dominated by muscovite and goethite in our field campaign fourteen sites eleven acid intrusion related and three structure associated distributed throughout the study area were inspected all of which proved to be of geological genesis our study led to the discovery of three mineralization sites associated with acid intrusions and structures that were not previously documented due to the extensively distributed acid intrusions and structures along the southern tianshan belt several other gold iron copper mineralized locations could be found with more detailed investigations our mineral prospecting methodology proved effective in the study area and is hereby suggested for application in similar geological settings

introduction to special issue on geologic remote sensing abstract herein we provide an overview of science and technology involved in remote sensing and outlines some practical constraints in applications to geological problems we further summarize diagnostic spectral features of important geological material that can be detected using satellite and air borne remote sensing finally the papers contained in the special issue are briefly introduced

the application of advanced space borne thermal emission and reflection aster radiometer data in the detection of alteration in the chadormalu paleocrater bafq region central iran abstract ore deposits are often produced by fluid flow processes that alter the mineralogy and chemistry of the country rock one of the main objectives in developing a multi spectral and hyperspectral sensor is to detect the optical characteristics of the earth s surface using hundreds of spectral bands all previous studies show that remote sensing can recognize alteration to different degrees using different spatial and spectral resolution sensors the aster sensor measures reflected radiation in vnir swir and tir electromagnetic energies it is cheap and easily available the alteration minerals in the precambrian chadormalu area chadormalu paleocrater and the related iron oxide deposit have been investigated in the field and have been successfully detected by applying iarr internal average relative reflectance fcc false color composite decorrelation stretch mnf minimum noise fraction transform correlated filter and mem mathematical evaluation method techniques on aster imageries sodic potassic and silicic phyllic alteration patterns can be distinguished this study shows that the capability and accuracy of the mem method is better than 2 2 correlated filter techniques results indicate that pervasive hydrothermal ore forming processes were important in the study area judging from the assemblage of alteration minerals the chadormalu iron deposit is an end member of the kiruna type iron oxide cu au ore deposit continuum

a statistical study on the characteristics of ionospheric storms in the equatorial ionization anomaly region gps tec observed over taiwan 1 positive and negative signatures of the ionospheric storms caused by the penetration electric field disturbance dynamo neutral wind neutral composition etc have been reported in this paper the ionospheric total electron content tec derived from the records of a network of ground based gps receivers in taiwan is used to statistically study the characteristics such as local time of appearance and duration of the storm signatures of various casuals in the equatorial ionization anomaly eia region during 1994 2003 a bias corrected accelerated bootstrap method and a z test are employed for the first time to detect each event and the overall storm signatures and characteristics respectively it is found that the positive signatures that appeared minutes to hours after the geomagnetic storm onset are pronounced on the storm day and the next day while the negative signatures that started hours after the geomagnetic storm onset can last for as long as the next 4 days the positive signature is statistically significant and most pronounced when the intense geomagnetic storm onset occurs during local afternoon which suggests that the signature may result from a combination of the prompt penetration electric field effect and mechanical effects of equatorward neutral wind additionally the negative signature that is statistically significant and most pronounced in the local afternoon of the storm onset day and or the next day may be produced by the disturbance dynamo or overshielding effects the long lasting negative signature occurred in local midnight noon period on days 2 4 after the storm onset may result from the neutral composition disturbances

reprint of introduction to special issue on geologic remote sensing abstract herein we provide an overview of science and technology involved in remote sensing and outlines some practical constraints in applications to geological problems we further summarize diagnostic spectral features of important geological material that can be detected using satellite and air borne remote sensing finally the papers contained in the special issue are briefly introduced

hyperspectral reflectance mapping of cinder cones at the summit of mauna kea and implications for equivalent observations on mars 1 atmospherically corrected hyperspectral reflectance data 0 4 to 2 5 m derived from the airborne visible infrared imaging spectrometer aviris validated with field based traverses and laboratory analyses were used to map the distribution of ferric oxide sulfate and phyllosilicate minerals exposed on fresh and altered cones on the summit of mauna kea volcano hawaii spectra from 0 4 to 1 1 m exhibit charge transfer and electronic transition features related to hematite nanophase iron oxide and possibly jarosite whereas spectra from 2 0 to 2 5 m are characterized by cation oh features related to kaolinite montmorillonite and saponite unaltered cones exhibit concentric zoning of iron oxide signatures with crystalline hematite located near the summits and nanophase iron oxide signatures found at the base of cones and on flow surfaces altered cones puu poliahu and puu waiau have exposures of three phyllosilicate and possible jarosite units in some cases there is zoning with a core of saponite surrounded by montmorillonite kaolinite is only found in two exposures on puu poliahu with one exposure coinciding with a possible jarosite unit the relatively small spatial scale associated with alteration zones seen on mauna kea demonstrates the importance of obtaining high spatial resolution hyperspectral observations of mars

underwater hyperspectral imaging using a stationary platform in the trans atlantic geotraverse hydrothermal field underwater hyperspectral imaging is a relatively new method for characterizing seafloor composition to date it has been deployed from moving underwater vehicles such as remotely operated vehicles and autonomous underwater vehicles while moving vehicles allow relatively rapid surveying of several 10 1000 m2 they are subjected to short term variations in vehicle attitude that often compromise image acquisition and quality in this study we tested a stationary platform that was landed on the seabed and used an underwater hyperspectral imager uhi on a vertical swinging bracket the imaged seafloor areas have dimensions of 2 3 m times 1 m and are characterized by very stable uhi data of high spatial resolution the study area was the trans atlantic geotraverse hydrothermal field at the mid atlantic ridge 26 n in water depths of 3530 3660 m uhi data were acquired a 12 stations on an active and an inactive hydrothermal sulfide mound based on supervised classification 24 spectrally different seafloor materials were detected including hydrothermal and non hydrothermal materials and benthic fauna the results show that the uhi data are able to spectrally distinguish different types of surface materials and benthic fauna in hydrothermal areas and may therefore represent a promising tool for high resolution seafloor exploration in potential future deep sea mining areas

dione s spectral and geological properties abstract we present a detailed analysis of the variations in spectral properties across the surface of saturn s satellite dione using cassini vims data and their relationships to geological and or morphological characteristics as seen in the cassini iss images this analysis focuses on a local region on dione s anti saturnian hemisphere that was observed by vims with high spatial resolution during orbit 16 in october 2005 the results are incorporated into a global context provided by vims data acquired within cassini s first 50 orbits our results show that dione s surface is dominated by at least one global process bombardment by magnetospheric particles is consistent with the concentration of dark material and enhanced co 2 absorption on the trailing hemisphere of dione independent of the geology local regions within this terrain indicate a special kind of resurfacing that probably is related to large scale impact process in contrast the enhanced ice signature on the leading side is associated with the extended ejecta of the fresh impact crater creusa 49 n 76 w although no geologically active regions could be identified dione s tectonized regions observed with high spatial resolution partly show some clean h 2 o ice implying that tectonic processes could have continued into more recent times

rapid determination of coalbed methane exploration target region utilizing hyperspectral remote sensing abstract this study reveals the common surface mineral characteristics over coalbed methane cbm enrichment regions from spaceborne hyperion images and the possibility of hyperspectral remote sensing for prospecting coalbed methane exploration target region with an inexpensive large scale rapid and convenient way for this study a typical scheme including bands removal atmospheric correction snr estimation minimum noise fraction mnf pixel purity index ppi and n dimensional visualization was applied on hyperion image in qinshui basin china to accurately extract mineral endmembers the endmember spectra of carbonate and clay mineral were identified based on the diagnostic absorption feature while no endmember of ferrous iron mineral was found the absorption feature parameters of carbonate absorption position and especially asymmetric factor and clay mineral absorption position left and right shoulder positions were quantitatively estimated which showed the endmember spectra of carbonate and clay mineral from hyperspectral images in this paper were correct in addition this study proposed an interesting research direction measuring the asymmetric absorption factor to facilitate the identification of carbonates furthermore spectral angle mapper sam and spectral feature fitting sff were used to map carbonates and clay minerals two assessment methods visual interpretation based on field spectra and x ray diffraction xrd analysis were utilized to evaluate the mapping accuracy which showed total agreements of 84 03 and 72 58 respectively the results in this paper suggested that both carbonates and clay minerals were rich while there was hardly any ferrous iron mineral on the surface of cbm enrichment regions in addition another similar experiment was carried out in ordos basin and also showed similar surface mineral characteristics on cbm enrichment region

mean neutral circulation in the winter polar f region direct measurements of the f region neutral wind field in the northern winter hemisphere during late november and december 1981 were obtained by using the dynamics explorer de 2 satellite and the network of ground based fabry perot interferometers sited in the north american and scandinavian sectors all available data for the study period have been collated and averaged according to universal time ut to provide a global scale experimental determination of the mean or average circulation in the northern hemisphere f region the data are organized into ut bins and are presented as a sequence of 12 climate maps depicting the neutral wind system at 2 hour ut intervals during a mean day in december 1981 the data set provides the most comprehensive experimental measure of the global scale high latitude thermospheric circulation yet reported the averaged measurements from the different instruments exhibit a satisfactory degree of internal consistency when viewed in terms of the global scale neutral flow a detailed comparison with the predictions of the ncar thermospheric general circulation model is discussed the model predictions are in good general agreement with the ut dependent mean circulation reproducing the basic control of the high latitude neutral wind system by ion drag forces modulated in ut as a result of the offset between the geomagnetic and geographic poles differences in flow directions and velocities between model predictions and experimental results are ascribed to natural variability in the thermosphere as well as to the use in the model of a less than fully realistic symmetric ion convection geometry and density distribution the two basic conclusions of this study are that 1 instrumentation deployed around the globe and on satellites can provide powerful composite data sets that can be used to monitor global scale mean thermospheric climatology and that 2 the mean thermospheric f region neutral circulation for the given geophysical situation solar maximum near solstice can be modeled reasonably well using a three dimensional time dependent model with appropriate parameterizations for the energy and momentum inputs

lunar mare basalts in the aristarchus region implications for the stratigraphic sequence from clementine uvvis data the aristarchus region of oceanus procellarum is an area concentrated with lunar basalts which were mainly produced by the last major phase of lunar volcanism on the western nearside a group of lunar sample and remote sensing scientists have carried out the extensive task of characterization of lunar mare soils with regard to their mineralogical and chemical makeup and regional geologic mapping spectral parameters of the high spatial resolution clementine images are used to identify and define these basalts as different compositional and spectral units this endeavor is aimed at deciphering the subtle spectral characteristics of mare soils and validating the mapping technique used in this study together with making statistical analysis of the links between the basalt types with ages in order to provide a further understanding of material types and geologic evolution in the aristarchus region of the moon from the new perspective of mining geologic information in multivariable image spaces spectrally distinct 9 high ti and 11 low ti basalt reference spectra have been distinguished and as a result more than 70 spectrally and compositionally basaltic units which range in age from 1 20 b y to 3 74 b y have been identified to some extent a potential relationship between composition and relative age exists in the statistical analysis of the links between spectral types related with the clementine ratio colors of various basalts and ages in this study which suggests that composition with different states of maturity correlate with age to some extent the mineralogical characteristics and spectra age relationship in the marius hills region indicate that the early basalts may still be exposed at the surface deposit after prolonged volcanic activity in this region this may be a result of not being blanketed by later lava flows or lava extrusions of underlying low ti basalts in addition stratigraphic analysis also reveals and confirms that tio 2 concentrations appear to vary independently with time and generally eruptions of

modelling ore forming processes through a cosine similarity measure improved targeting of porphyry copper deposits in the manzhouli belt china abstract recognizing distribution patterns of ore related pathfinder elements requires an understanding of the corresponding ore forming systems and may lead to the definition of more reliable exploration targets given that complex ore forming processes in complex geological terrains can result in either enrichment or depletion of ore elements simultaneous consideration of both processes in geochemical anomaly modelling would be advantageous for defining exploration targets here we adapted the cosine similarity measure method for pattern recognition of ore related geochemical anomalism to facilitate simultaneous modelling of element enrichment and depletion we tested the performance of this new method on porphyry copper exploration data from the manzhouli belt china and demonstrated that our method is highly efficient with respect to recognizing ore related geochemical signatures and thus useful for vectoring towards porphyry copper deposits and defining more reliable geochemical exploration targets

a theoretical study of thermospheric composition perturbations during an impulsive geomagnetic storm the compositional response of the neutral thermosphere to an impulsive geomagnetic storm has been investigated using a numerical simulation made with the national center for atmospheric research thermospheric general circulation model ncar tgcm calculated time dependent changes in neutral thermospheric composition have been studied together with detailed neutral parcel trajectories and other diagnostic information from the model to gain a greater understanding of the physical mechanisms responsible for composition variability during geomagnetic storms and in particular to investigate the causes of the positive and negative ionospheric storm effects the following principal results were obtained from this study 1 calculated perturbations in thermospheric composition following the onset of an impulsive geomagnetic storm were found to be in good qualitative agreement with the previous experimental statistical study of storm time thermospheric morphology by prolss 1981 2 during the initial onset phase of the simulated storm upward vertical winds occurred in the auroral zone and downward winds occurred in the central magnetic polar cap 3 the largest perturbations in mass mixing ratio of nitrogen n2 at f region altitudes were found to be associated with parcels of neutral gas that travelled through the cusp region and with parcels that were trapped within the auroral zone for a long time 4 storm time enhancements in n2 were found to occur in the midnight and early morning sectors both within and equatorward of the auroral zone and these were determined to be associated with the advective effects of the large antisunward polar cap neutral winds the physical size of the region of enhanced n2 values was determined to be related to the time taken for individual parcels of air to corotate out of the large day to night thermospheric wind jet and thus to the magnitudes of the antisunward polar cap winds 5 decreases in n2 were found to occur in regions of downward vertical winds and in regions into which relatively nitrogen poor air was advected by the horizontal wind 6 calculated compositional perturbations following the onset of the storm were found to propagate to mid latitudes due to the advective effects of equatorward winds leading to the mid latitude positive ionospheric storm effects this last result is in disagreement with the earlier study of rishbeth et al 1985 who found the compositional disturbance to be largely restricted to the auroral zone on a constant pressure surface however it is consistent with the more recent study undertaken by fuller rowell et al 1991 who demonstrated that composition changes were seen well beyond the auroral oval

negative ionospheric storm coincident with de 1 observed thermospheric disturbance on october 14 1981 the de 1 far ultraviolet fuv imaging instrument recorded a large thermospheric disturbance over europe and russia on october 14 1981 during a geomagnetic storm commencing near the end of the previous day the disturbance is quantified in terms of o n2 the column density ratio referenced to a fixed depth in n2 the ratio is derived from de 1 dayglow observations with a filter whose signal transmission is dominated by o i 130 4 nm emission within the disturbed region o n2 is less than that in surrounding regions with minimum values being more than a factor of 2 smaller than undisturbed values images of o n2 are compared to ground based ionosonde data from 13 sites some within and others outside of the disturbed region the data are in the form of nmax the maximum electron density which in the presence of an f2 layer is equivalent to nmf2 the data exhibit negative ionospheric storm effects reduced nmax within the disturbed region and normal behavior elsewhere the degree of correlation between o n2 and nmax suggests that the approximate geographical extent of dayside regions experiencing negative ionospheric storm effects can be determined from global fuv imaging of the disturbed and surrounding regions the analysis is extended to the following day to address the recovery of the disturbed region the o n2 ratio has returned to undisturbed values except in a smaller disturbance region containing weak reductions in o n2 this is either a remnant of the strong disturbance from the day before or a newly formed disturbance from substorm activity several hours prior to the new observations only the ionosonde sites within this region recorded values of nmax below their monthly median values

vertical variations in the n2 mass mixing ratio during a thermospheric storm that have been simulated using a coupled magnetosphere ionosphere thermosphere model 1 the center for integrated space weather modeling s cism suite of models was run together to simulate the passage of an idealized coronal mass ejection cme from the sun s corona to geospace the resulting interplanetary magnetic field imf pattern included a period during which bz was southward the effects of this cme were then propagated through the lyon fedder mobarry lfm model of the magnetosphere to study its influence on the earth s ionosphere and thermosphere the effect of these changes on the thermosphere ionosphere nested grid ting model was to drive a large ionospheric and thermospheric storm this storm had higher potentials than one would expect from the magnitude of the southward excursion of bz changes in n2 mmrs were analyzed to investigate their height variations rather than attempting to make any detailed comparison with data several conclusions were drawn from this study 1 the results were consistent with previous data and modeling studies of composition changes on a horizontal surface 2 neutral composition was severely affected by this storm with large increases in the relative densities of the molecular species first being seen in the high and middle latitudes of the night and early morning sectors and later at all local times 3 the observed changes were larger than might be expected from the imf 4 most upwelling occurred in the dayside auroral oval far less upwelling occurred in the nightside auroral oval 5 the large scale circulation of the storm on the nightside created an overturning in the middle latitudes 6 this overturning was primarily the result of molecular rich air being transported horizontally over air that was not as rich in the molecular species 7 the overturning acted as a diffusive barrier that prevented molecular diffusion from driving recovery to the thermosphere s quiet time compositional distribution 8 the large scale circulation has the potential to directly mix the thermosphere on relatively short timescales

hydrothermal alteration mapping at bodie california using aviris hyperspectral data abstract aviris data covering the bodie and neighboring paramount mining districts eastern california were used to map hydrothermal alteration minerals two spectral analysis algorithms were used spectral angle mapper sam and tricorder the objective was to compare the performance of the two algorithms where no a priori ground or atmospheric information is available aviris data were calibrated to apparent surface reflectance using a modified modtran radiative transfer model in conjunction with laboratory and in flight calibration data both algorithms appear to produce satisfactory results for geologic reconnaissance and mapping applications but tricor der generally classified more pixels and identified more mineral species than sam for some minerals such as na montmorillonite results from tricorder and sam matched reasonably well but major differences appeared in how the two algorithms classified kaolinite group minerals and ferric oxides laboratory spectra of rock samples from five localities were compared to reference spectra of minerals identified by the classification algorithms for corresponding pixels with the results matching to some extent

the geomagnetic quiet nighttime thermospheric wind pattern over fritz peak observatory during solar cycle minimum and maximum nighttime thermospheric winds and temperatures at f region heights have been measured over fritz peak observatory colorado 39 9 n 105 5 w with a high resolution fabry perot spectrometer from about november 1972 to the present the winds and temperatures are obtained from the doppler shifts and line profiles of the o i 15 867 k 630 nm line emission the data obtained during geomagnetic quiet conditions ap 20 have been separated into two groups representing solar cycle minimum conditions 1972 1977 and solar cycle maximum conditions 1978 1979 the monthly variation of the nighttime zonal and meridional winds are presented for both groups the results show that during solar cycle minimum the zonal winds are predominantly eastward during the winter months at speeds of 50 75 m s 1 and westward during the summer months at speeds of 50 100 m s 1 the meridional winds measured to the north and south of fritz peak observatory are equatorward throughout most of the night at nearly the same speed the equatorward winds in the summer peak near midnight at about 100 150 m s 1 the equatorward winds in the winter also peak near midnight but with smaller speeds 50 75 m s 1 during solar cycle maximum the zonal winds are again predominantly eastward during the winter months reaching peak speeds of 60 75 m s 1 in the early evening hours and decreasing afterward in the summer the winds are eastward during the early evening hours shifting to westward near midnight and increasing to a maximum speed of 75 100 m s 1 in the early morning hours the meridional winds are poleward at 20 m s 1 in the early evening hours shifting to equatorward near 2100 lt and then increasing in magnitude with maximum speeds near or after midnight there is a considerable difference in the speed of the winds measured to the north and south of fritz peak observatory during the summer the equatorward winds measured to the north are 150 175 m s 1 whereas the equatorward winds measured to the south are 50 75 m s 1 during the winter the speeds are smaller 50 75 m s 1 and 25 30 m s 1 to the north and south of the station respectively calculations made with the national center for atmospheric research thermospheric general circulation model for different seasons are in reasonable agreement with the observations during both solar minimum and solar maximum during solar cycle maximum the observed and calculated meridional wind differences to the north and south of fritz peak observatory are attributed to enhanced auroral heating and ion drag associated with magnetospheric convection north of the observatory the equatorward driven winds slow south of fritz peak observatory owing to the diminishing influence of high latitude forcings

remote sensing for mineral exploration abstract remote sensing is the science of acquiring processing and interpreting images and related data acquired from aircraft and satellites that record the interaction between matter and electromagnetic energy remote sensing images are used for mineral exploration in two applications 1 map geology and the faults and fractures that localize ore deposits 2 recognize hydrothermally altered rocks by their spectral signatures landsat thematic mapper tm satellite images are widely used to interpret both structure and hydrothermal alteration digitally processed tm ratio images can identify two assemblages of hydrothermal alteration minerals iron minerals and clays plus alunite in northern chile tm ratio images defined the prospects that are now major copper deposits at collahuasi and ujina hyperspectral imaging systems can identify individual species of iron and clay minerals which can provide details of hydrothermal zoning silicification which is an important indicator of hydrothermal alteration is not recognizable on tm and hyperspectral images quartz has no diagnostic spectral features in the visible and reflected ir wavelengths recorded by these systems variations in silica content are recognizable in multispectral thermal ir images which is a promising topic for research

auroral zone thermospheric dynamics 1 averages forty four nights of thermospheric neutral wind and temperature measurements were obtained with a ground based fabry perot spectrometer at college alaska 65 invariant latitude mostly during high to moderate levels of solar activity the spectrometer scanned the o i 15 867 k 6300 a emission line yielding line profile measurements that originate from an altitude range between 170 and 280 km the observed average wind direction is to the northwest in the early evening changing to the south near midnight and then to the southeast in the morning the overall wind pattern generally persists but the wind speed increases with increasing geomagnetic activity a change in the zonal wind direction occurs earlier in magnetic local time with increasing magnetic activity the meridional wind pattern also shifts equatorward with the auroral oval during increasing magnetic activity consequently the average wind pattern in the north during low geomagnetic activity is rather similar to the moderate activity average in the south and the moderate geomagnetic activity average wind pattern in the north is similar to the high geomagnetic activity average in the south the observed average thermospheric temperature is found to be governed by geomagnetic activity and the previous day s 10 7 cm solar flux

study on identification of altered rock in hyperspectral imagery using spectrum of field object abstract in this article the spectrum of a field object was used to match the pixel spectrum in the hyperspectral imagery and determine whether there existed a dominant object in the pixel and to what extent the dominant object was present based on these recognition results altered rock in the hyperspectral imagery was identified the spectrum of a field object was obtained from field surveys in the study area and in the spectrum there was only one main object that could be effectively identified this main object was named as the dominant object in this paper in this study the overall shape of the spectrum was matched firstly and then the correlation coefficients between the pixel spectrum and the spectrum of field object in the corresponding wavelength ranges of the absorption bands were calculated to determine the matching effect of these spectra as well as the possibility that the dominant object existed in the pixel the recognition results were expressed by two images the first image was a figure that illustrated the dominant objects in the pixels the second image was a figure showing the correlation coefficients the study area was a primitive forest covered region located in the pulang porphyry copper mining area zhongdian county of yunan province china the figures illustrating the distribution of the altered rocks and the correlation coefficient were obtained from this study the on site verification showed that using the spectra of field objects it was possible to identify the dominant objects in the pixels which favored the identification of altered rocks in the image moreover compared to considering only the overall shape the recognition results obtained by considering the overall and partial shape of the spectra had higher reliability

ionospheric and thermospheric response over millstone hill to the may 30 1984 annular solar eclipse the national center for atmospheric research ncar thermospheric general circulation model tgcm is used to calculate the time dependent thermospheric response to the may 30 1984 annular solar eclipse the path of maximum obscurity begins at sunrise in the pacific ocean near 2 n and 135 w it moves northeastward passing across central mexico the eastern united states and then the atlantic before ending near 28 n and 4 e in algeria the area of the partial shadow is relatively large and the total solar flux incident on the dayside of the earth is decreased by about 6 during the eclipse the tgcm calculates the time dependent response of the winds temperature and the mass mixing ratios of the major constituents throughout the thermosphere perturbations follow the path of the annular eclipse with maximum deviations occurring near 1700 ut at about 300 km for the temperature and at higher altitudes for the winds and composition the perturbation winds converge from all directions toward the shadow at speeds reaching 75 m s 1 in the upper thermosphere the maximum temperature anomaly 55 k and vertical wind anomaly 7 m s 1 occur near the center of the shadow at a constant altitude of 300 km both the n2 density and the o density decrease by about 10 and 6 respectively the path of maximum obscuration passes within 3 of latitude of the incoherent scatter radar at millstone hill massachusetts 42 6 n 71 5 w the station experiences a maximum solar obscuration of 86 at 1700 ut 1200 lt a time dependent one dimensional numerical model of the ionosphere that uses the tgcm calculated winds temperature and composition at millstone hill is used to calculate the electron and ion densities and temperatures and the densities of the odd nitrogen species no n 4s and n d during the eclipse the calculated electron density decreases by about factors of 2 in the f region 4 in the f1 region and 3 in the e region compared to a similar control run without an eclipse the f1 region emerges during the eclipse with an increase in the no o ratio the calculated electron temperature decreases by 460 k during the eclipse but then increases 200 k following the eclipse because of the intense solar heating in a region of reduced electron densities the calculated ion temperature generally follows the changes in neutral temperature the calculated thermospheric and ionospheric responses agree well with measurements made by the millstone hill incoherent scatter radar