a fully polarimetric sar imagery classification scheme for mud and sand flats in intertidal zones sediments on exposed intertidal flats are very dynamic and perform vital ecosystem functions this paper proposes a new classification scheme for mud and sand flats on intertidal flats using fully polarimetric synthetic aperture radar sar data freeman durden fd and cloude pottier cp polarimetric decomposition components as well as double bounce eigenvalue relative difference derd are introduced into the feature sets instead of the original intensity polarimetric channels classification is carried out using the random forest rf theory and the results are evaluated using confusion matrices kappa coefficients and rf variable importance indices three study sites with different environmental conditions are chosen to demonstrate the effectiveness of the proposed classification chain to further assess the performance of the proposed feature set we set different feature combinations and process with the same processing chain results show that the derd parameter can detail the sediment mappings on exposed intertidal flats and is a useful sar feature to distinguish mud and sand flats efficiently the combined fd and cp components have the ability to describe the polarimetric characteristics of sediments more correctly than the commonly used original intensity channels meanwhile the rf theory shows great potential in distinguishing sediments in intertidal zones accurately and time efficiently

classification of sediments on exposed tidal flats in the german bight using multi frequency radar data we present a new method for the extraction of roughness parameters of sand ripples on exposed tidal flats from multi frequency synthetic aperture radar sar data the method is based on the integral equation model iem which predicts the normalized radar cross section nrcs of randomly rough dielectric surfaces the data used for this analysis were acquired in the german bight of the north sea by the spaceborne imaging radar c x band sar sir c x sar in 1994 in situ measurements of the root mean squared rms height and the correlation length of the sand ripples clearly demonstrate a relationship between these roughness parameters and the c band nrcs determined from an ers sar image using the iem we have calculated nrcs isolines for the three frequency bands deployed by sir c x sar l c and x band as a function of the rms height and the correlation length of the sand ripples for each sir c x sar image pixel these two roughness parameters were determined from the intersections of the nrcs isolines at different radar bands and they were used for a crude sediment classification for a small test area at the german north sea coast comparing our results with available sediment maps we conclude that the presented method is very promising for tidal flat classification by using data from presently existing airborne and future spaceborne multi frequency sar systems

three dimensional architecture and hydrostratigraphy of cross cutting buried valleys using airborne electromagnetics glaciated central lowlands nebraska usa buried valleys are characteristic features of glaciated landscapes and their deposits host important aquifers worldwide understanding the stratigraphic architecture of these deposits is essential for protecting groundwater and interpreting sedimentary processes in subglacial and ice marginal environments the relationships between depositional architecture topography and hydrostratigraphy in dissected pre illinoian till sheets is poorly understood boreholes alone are inadequate to characterize the complex geology of buried valleys but airborne electromagnetic surveys have proven useful for this purpose a key question is whether the sedimentary architecture of buried valleys can be interpreted from airborne electromagnetic profiles this study employs airborne electromagnetic resistivity profiles to interpret the three dimensional sedimentary architecture of cross cutting buried valleys in a ca 400 km2 area along the western margin of laurentide glaciation in north america a progenitor bedrock valley is succeeded by at least five generations of tunnel valleys that become progressively younger northward tunnel valley infills are highly variable reflecting under filled and over filled conditions under filled tunnel valleys are expressed on the modern landscape and contain fine sediments that act as hydraulic barriers over filled tunnel valleys are not recognized in the modern landscape but where they are present they form hydraulic windows between deep aquifer units and the land surface the interpretation of tunnel valley genesis herein provides evidence of the relationships between depositional processes and glacial landforms in a dissected pre illinoian till sheet and contributes to the understanding of the complex physical hydrology of glacial aquifers in general this article is protected by copyright all rights reserved

airborne electromagnetic footprints in 1d earths existing estimates of footprint size for airborne electromagnetic aem systems have been based largely on the inductive limit of the response we present calculations of frequency domain aem footprint sizes in infinitehorizontal thin sheet and half space models for the case of finite frequency and conductivity in a half space the original definition of the footprint is extended to be the side length of the cube with its top centered below the transmitter that contains the induced currents responsible for 90 of the secondary field measured at the receiver for a horizontal coplanar helicopter frequency domain system the in phase footprint for induction numbers less than 0 4 thin sheet or less than 0 6 half space increases from around 3 7 times the flight height at the inductive limit to more than 10 times the flight height for a vertical coaxial system the half space footprint exceeds nine times the flight height for induction numbers less than 0 09 for all models geometries and frequencies the quadrature footprint is approximately half to two thirds that of the in phase footprint these footprint estimates are supported by 3d model calculations that suggest resistive targets must be separated by the footprint dimension for their individual anomalies to be resolved completely analysis of frequency domain aem field data acquired for antarctic sea ice thickness measurements supports the existence of a smaller footprint for the quadrature component in comparison with the in phase but the effect is relatively weak in phase and quadrature footprints estimated by comparing aem to drillhole data are considerably smaller than footprints from 1d and 3d calculations however we consider the footprints estimated directly from field data unreliable since they are based on a drillhole data set that did not adequately define the true 3d sea ice thickness distribution around the aem flight line

joint use of multiple synthetic aperture radar imagery for the detection of bivalve beds and morphological changes on intertidal flats abstract we analyzed a large amount of high resolution synthetic aperture radar sar data of dry fallen intertidal flats on the german north sea coast with respect to the imaging of sediments macrophytes and mussels terrasar x and radarsat 2 images of four test areas acquired from 2008 to 2013 form the basis for the present investigation and are used to demonstrate that pairs of sar images if combined through basic algebraic operations can already provide indicators for morphological changes and for bivalve oyster and mussel beds multi temporal analyses of series of sar images allow detecting bivalve beds since the radar backscattering from those beds is generally high whereas that from sediments may vary with imaging geometry and environmental conditions our results further show evidence that also single acquisition dual polarization sar imagery can be used in this respect the polarization coefficient i e the ratio of the difference and the sum of both co polarizations can be used to infer indicators for oyster and blue mussel beds

excess argon in k ar and ar ar geochronology the k ar and ar ar dating techniques occasionally produce anomalously old ages attributed to excess argon and such data is often rejected as not offering any insight into the age thermal history or geochemistry of the rock however improvements in the quantification of argon geochemistry now provide a framework to model excess argon in both open and closed systems solubility data for argon in hydrous fluids melts and emerging data for minerals can be used to understand the behaviour of excess argon and provide valuable insights into the environment in which the samples cooled to their argon retention or closure temperature treating excess argon as a trace element also throws light on its behaviour in minerals above the closure temperature in deeply buried dry systems such as eclogites blueschists granulites and even in the lithospheric mantle extremely low partition coefficients between k feldspar and hydrous fluid phases predict lower excess argon susceptibility than micas and this is observed in fluid poor systems variation of partition coefficients can lead to excess argon in fluids being introduced into minerals or removed from minerals as grain boundary fluids change during flow through a rock however excess argon can also be introduced or removed from minerals by varying temperature without the need for fluid flow high mineral melt and mineral fluid partition coefficients are also the reason why excess argon is often concentrated in inclusions within minerals partition coefficients between minerals and hydrous fluids as low as 10 6 lead fluid inclusions to dominate the radiogenic argon budget particularly in low potassium minerals melt inclusions are less dominant but become critical in dating younger samples

osmium sulphur and helium isotopic results from the giant neoproterozoic epithermal imiter silver deposit morocco evidence for a mantle source the giant epithermal ag hg deposit of imiter anti atlas morocco was investigated to study the transfer of chalcophile elements from the mantle to superficial crustal levels the origin of metals and ligands sulphides was deduced from s fluid inclusions he and re os data obtained on sulphide phases and gangue minerals sulphur isotope analyses show the existence of two distinct isotopic reservoirs one found in pyrite from the surrounding black shale country rocks 34scdt 38 and the other in pyrites associated with a synchronous rhyolitic dome 34scdt 7 to 2 the 34scdt values of the silver mineralization event range from 28 to 2 and are interpreted as resulting from preferential degassing of so2 in ascending fluids as well as mixing between the magmatic isotopic reservoir and a country rock reservoir helium isotope analyses of sulphides and gangue minerals yield similar results with 3he 4he ratios ranging from 0 76 to 2 64ra these data and the absence of 20ne in the analyzed fluid inclusions suggest a mantle origin for the fluids associated with the epithermal silver event os isotopic ratios have been measured for the first time in ag and ag sulphosalts these data and those obtained on other sulphide phases directly associated with the ag mineralization show measured 187os 188os ratios of 0 142 0 197 indicating a dominantly mantle source for the associated os assuming that os and ag are derived from the same source the black shale country rock provided less than 10 of the silver metal stock this study highlights the conditions required to transfer 8000 metric tons of ag and other elements such as hg co ni pb zn from the mantle i e i an efficient vector such as the sulphide ligand ii a major and sudden break in the geodynamic environment similar to the one which occurred near the precambrian cambrian transition to provide pathways from the mantle wedge and the lithospheric base to the surface and iii a strongly extensional tectonic setting to provide traps for the concentration of metals in ore deposits

40ar 39ar ages and duration of the central atlantic magmatic province volcanism in morocco and portugal and its relation to the triassic jurassic boundary the central atlantic magmatic province camp is the world s largest known continental igneous province and is 15 contemporaneous with the triassic jurassic t j boundary that marks one of the five largest biological extinctions in the last 16 600 ma although constraints on the duration of the camp volcanism remain yet poorly defined the assumption that the camp 17 may have had a causal relationship with the climatic and biotic crisis was suggested marzoli a bertrand h knight k cirilli 18 s buratti n verati c nomade s renne p r youbi n martini r allenbach k neuwerth r rapaille c zaninetti l 19 bellieni g 2004 synchrony of the central atlantic magmatic province and the triassic jurassic boundary climatic and biotic 20 crisis geology 32 973 976 in this paper we present new 40ar 39ar ages on basaltic flows from moroccan central high atlas 21 oujda and argana and portuguese algarve and santiago do cacem basins where camp lava flows are interlayered with t j 22 sedimentary sequences 23 in the moroccan basins where the basalts were erupted across the t j boundary well defined 40ar 39ar plateau ages n 12 24 for more than 90 of the total erupted volume of camp basalts range from 197 8 0 7 ma to 201 7 2 4 ma and display a main 25 restricted peak at 199 1 1 ma providing a precise estimate of the 40ar 39ar age of the t j boundary concordant with the current 26 u pb age 199 6 0 3 ma palfy j mortensen j k carter e s smith p l friedman r m tipper h w 2000 timing the 27 end triassic mass extinction first on land then in the sea geology 28 39 42 the topmost lava flows recurrent unit yield a 28 significantly younger mean age of 196 6 0 6 ma highlighting late episodic eruption of camp magmas these late basalts 29 represent a small magma volume b10 of the total which was erupted most likely due to asthenospheric upwelling and 30 lithospheric extension within the t j central high atlas basins 31 in the portuguese basins stratigraphical and palynological studies of the associated continental sedimentary sequence 32 underlying the volcanic units suggest an age close to the t j boundary for the camp basaltic flows this is confirmed by new 33 40ar 39ar data for the portuguese basalts which provide the first accurate radio isotopic ages for lava flows in the european 34 camp with two plateau ages yielding a mean value of 198 1 0 4 ma these plateau ages plus three concordant mini plateau 35 ages suggest synchronous rifting and volcanism both in south western europe and morocco central high atlas and oujda basins in summary the eruptive history of the camp with an early extremely widespread and intense peak at 199 1 ma and a tail of 37 episodic eruption events until 196 6 ma is consistent with the biotic turnover at the t j boundary which was likely caused by 38 devastating effects of extensive volcanic eruptions

the thermal significance of potassium feldspar k ar ages inferred from age spectrum results 40ar39ar age spectrum analyses of three microcline separates from the separation point batholith northwest nelson new zealand which cooled slowly 5 c ma 1 through the temperature zone of partial radiogenic 40ar accumulation are characterized by a linear age increase over the first 65 percent of gas release with the lowest ages 80 ma corresponding to the time that the samples cooled below about 100 c the last 35 percent of 39ar released from the microclines yields plateau ages 103 99 and 93 ma which reflect the different bulk mineral ages and correspond to cooling temperatures between about 130 to 160 c theoretical calculations confirm the likelihood of diffusion gradients in feldspars cooling at rates 5 c ma 1 diffusion parameters calculated from the 39ar release yield an activation energy e 28 8 1 9 kcal mol 1 and a frequency factor grain size parameter d0l2 5 6 3 9 14sec 1 this arrhenius relationship corresponds to a closure temperature of 132 13 c which is very similar to the independently estimated temperature from the observed diffusion compensation correlation this d0l2 implies an average diffusion half width of about 3 m similar to the half width of the perthite lamellae in the feldspars the range in microcline k ar ages from the separation point batholith is the result of relatively small temperature differences within the pluton during cooling comparison of the diffusion laws determined for microcline with those for anorthoclases and other homogeneous k feldspars e 40 to 52 kcal mol 1 reveals that ar diffusion is more highly temperature dependent in the disordered structural state than in the ordered structural state previously published u shaped age spectra are probably the result of the superimposition of excess 40ar upon diffusion profiles of the kind described here

40ar 39ar dating and geochemistry of tholeiitic magmatism related to the early opening of the central atlantic rift tholeiitic effusive and intrusive magmatism from iberia morocco algeria and mali related to the early opening of the central atlantic rift was dated by the 40ar 39ar step heating method four plateau ages ranging from 203 7 2 7 to 197 1 1 8 ma were obtained on plagioclase from dykes from the taoudenni area mali and two lava flows from morocco the messejana dyke iberia which previously yielded discrepant conventional kar dates did not furnish any 40ar 39ar plateau dates however there is a clear inverse relationship between apparent age and k ca ratio for gas fractions from a plagioclase separate proportional to the alteration degree which combined with dates obtained on amphibole biotite and pyroxene allows us to determine an age of around 200 ma for this body these data and those obtained on the foum zguid morocco and the ksi ksou algeria dykes give evidence of a brief magmatic event between 206 and 195 ma ago which affected a large area ca 2500 km long trace element modelling shows that most of these formations originated from a homogeneous enriched source material such a brief magmatic episode related to the opening of a continental rift is in agreement with findings in other magmatic provinces e g the deccan traps and the red sea rift precisely dated by the 40ar 39ar method as well

hercynian age of the cobalt nickel arsenide gold ores bou azzer anti atlas morocco re os sm nd and u pb age determinations the age of the hydrothermal co ni as au mineralization in the bou azzer el graara inlier was determined using different isotopic systems on ore and mineralization related gangue minerals namely re os on molybdenite sm nd on carbonates and u pb on brannerite re os dating of molybdenite was difficult owing to the intimate intergrowth of molybdenite with co arsenides and the fact that sampling by drilling complex sulfide mixtures resulted in poor concentration of molybdenite accordingly re os dating of the impure molybdenite sulfide mixtures yielded inconsistent ages in the range 400 to 350 ma this scatter is attributed to 1 inadequate concentration of pure molybdenite 2 complex re os systematics possibly involving excess radiogenic os derived from older generation s of sulfide and or 3 mixture of at least two re os systems consisting of a component with pre hercynian history and later disturbance by hercynian metamorphism carbonates and brannerite that coexist with molybdenite gave more consistent ages of 308 31 ma sm nd and 310 5 ma u pb respectively because both ages agree within their errors we regard the brannerite u pb age of 310 5 2 ma as the best and most precise estimate for the age of the co ni as au mineralization although an earlier onset of mineralization cannot be ignored totally the new age data underline that the principal co ni as au mineralization at bou azzer occupying the main ore bearing structures was driven by and formed during the end of the hercynian orogeny

detection of oyster habitat in tidal flats using multi frequency polarimetric sar data abstract exposed oyster reefs in tidal flats have complex and rough surfaces because of their unique surface texture which are quite distinct from the surrounding mud or sand flats here we investigate the microwave signatures backscattered from naturally distributed oyster reefs in tidal flats utilizing the polarimetric analysis techniques to fully polarimetric radarsat 2 c band and alos palsar l band data the study areas include the tidal flats around jebu island and hampyung bay on the west coast of the korean peninsula we analyzed the microwave scattering mechanisms associated with oyster reefs and surrounding areas using the polarimetric target decomposition theorem and quantitatively measu hhvv red target depolarization effects the cross polarized ratio hv vv the co polarized correlation coefficient hhvv and the co polarized phase difference between hh and vv on the basis of a large increase in the cross polarized backscattering hv in the c band sar data one can observe strong volume or multiple scattering and depolarization effects over oyster reefs areas whereas only surface scattering was dominant in most parts of the background tidal areas in oyster reefs the proportion of volume scattering and the cross polarized ratio were greater than 0 7 and 8 db respectively these scattering characteristics were also verified from in situ measurements in the field using a ground based polarimetric scatterometer system however almost no difference was observed between the scattering signatures of oyster reefs and background mudflat areas from l band data which have a considerably longer wavelength than c band the study clearly suggests that multi frequency c and l band polarimetric sar systems can be used to detect the naturally distributed oyster reefs in tidal flats

two dimensional mapping of sea ice keels with airborne electromagnetics airborne electromagnetic aem equipment can be used to sense sea ice thickness by interpreting the aem data to obtain the distance from the towed bird that holds the em system to the ice seawater interface the ice thickness itself is obtained by subtracting from that quantity the distance from the bird to the upper ice surface as determined by a laser altimeter to interpret aem data acquired over sea ice keels we first solve the forward problem using an integral equation approach to the neumann boundary value problem in this approach we assume that sea ice is an insulator and that seawater is a perfect conductor when the ice keel is two dimensional the pertinent equations can be transformed into the wavenumber domain along the strike direction resulting in the rapid numerical computation of the aem response by compiling numerical model results we constructed an interpretation chart that relates the parameters of the observed aem response anomaly to the geometric variables of the ice keel the

basinal brines at the origin of the imiter ag hg deposit anti atlas morocco evidence from la icp ms data on fluid inclusions halogen signatures and stable isotopes h c o the imiter ag hg deposit is located in the precambrian volcano sedimentary formations of the saghro inlier eastern part of the anti atlas mountains morocco the orebodies consist of northeast southwest to east west veins and lenses hosted by cryogenian black shales and gray wackes and neoproterozoic conglomerates and are controlled by an east west fault network the so called imiter fault mineralogical and paleo fluid geochemistry investigations microthermometry raman spectroscopy la icp ms on individual inclusions bulk crush leach analyses and stable isotope data o h show that the main ag ore stage is related to circulation of deep basinal sedimentary brines na k mg salinity 16 7 to 26 wt nacl equiv molar cl br 330 18 o 2 15 2 35 smow and d 53 8 to 65 5 smow at temperatures of about 180 to 220 c and hydrostatic pressures the main driving mechanism for silver ore deposition is the dilution of ore bearing brines by a low salinity meteoric fluid containing a low density volatile component n 2 ch 4 co 2 t h 180 to 220 c 18 o 1 4 smow and d of about 28 2 smow silver content of the brines ranges from 2 to 30 mmol kg solution up to 3 200 ppm ag avg ag concentration about 900 ppm whereas the maximum ag content found in dilute waters is about 0 4 mmol kg solution 40 ppm the ore forming model proposed for the imiter deposit is 1 ag extraction from the basement by the penetration of deep basinal brines and 2 deposition in a structural trap through fluid mixing with recharge fluids this model is comparable to that described worldwide for the origin of pb zn f ba and u deposits near unconformities between basement and sedimentary basins similarities among the major ag deposits from the anti atlas imiter zgounder bou azzer strongly suggest that they resulted from a unique event likely related to the opening of the atlantic ocean the silver ores are superimposed on the same lineament as a preexisting uneconomic pan african co ni as system linked to magmatic intrusions but ag ores have no genetic relationship with them

the footprint altitude ratio for helicopter electromagnetic sounding of sea ice thickness comparison of theoretical and field estimates helicopter towed electromagnetic hem induction sounding systems are typically used for geologic surveys more recently hem systems have been used for the remote measurement of sea ice thickness and shallow sea bathymetry an important aspect of this remote sensing technology is the area or footprint in which the secondary field is predominantly generated by induced currents a knowledge of the size of the footprint is important to understanding the accuracy of hem sounding results over lateral variations in relief or conductivity conventional wisdom among workers in the field held that the footprint diameter is a few times the hem antenna altitude we confirm this view using airborne measurements over sea ice to calculate the footprint size antenna altitude ratio these findings are compared to various theoretical estimates and are found to be in reasonable agreement for a vertical coaxial coil antenna arrangement the apparent footprint diameter was found to be about 1 3 times the antenna height a

airborne em footprints as frequency domain airborne electromagnetic aem studies move towards more detailed assessments of the near surface the behaviour of system footprints and hence the spatial averages involved in the measurement becomes important published estimates suffer from two main limitations first they are based on perfectly conducting thin sheet models and secondly they are system specific the present study is a revision of footprint estimates based on i a finitely conducting half space and ii an at surface scale estimate that uses the spatial equivalent of the conventional electromagnetic skin depth in order to remove the system dependence a transmitter footprint is defined in terms of electromagnetic skin distance only the limiting cases of vertical and horizontal magnetic dipole sources then require analysis electromagnetic skin distances two for each of the coil orientations are defined the revised definition makes it possible to investigate the footprint behaviour of both towed bird and fixed wing aem systems over an altitude range from 20 to 100 m the footprint altitude ratio has a primary dependence on altitude and a secondary dependence on both resistivity and frequency the analysis covers a frequency range from 1 to 100 khz and results are presented for two specific resistivity values that represent conductive 10 m and resistive 1000 m environments the revised footprint parameters display a quasi linear behaviour with altitude particularly for mid range frequencies this behaviour enables the coefficients of linear least squares relationships to be obtained thus assisting with the prediction of footprint estimates for survey planning and interpretation a comparison of the new estimates with published values suggests that existing footprint values for a vertical magnetic dipole should be revised downward

basinal brines at the origin of the imiter ag hg deposit anti atlas morocco evidence from la icp ms data on fluid inclusions halogen signatures and stable isotopes h c o a discussion we congratulate essarraj et al 2016 for their paper on the polymetallic ag hg imiter deposit anti atlas morocco which is one of the most intensely investigated yet still discussed mineral deposits in term of ore genesis in their contribution essarraj et al have employed fluid inclusion halogen and isotopic analyses in an attempt to constrain the genesis of the imiter ag hg deposit it is through detailed geochemical studies such as this that the origin s of this world class orebody will be deciphered their contribution represents a significant advance in the investigation of polymetallic hydrothermal deposits of the anti atlas however we feel compelled to stress certain problems with their interpretation important geologic attributes of the imiter deposit have been documented by numerous workers ouguir et al 1994 pasava 1994 baroudi et al 1999 cheilletz et al 2002 essarraj et al 2005 barral et al 2011 levresse et al 2005 2016 however there is a lack of direct age information to constrain the timing of hydrothermal activity and duration of vein filling during the silver mineralizing event s this age uncertainty has resulted in the proposal of several conflicting models involving different fluid sources and genetic processes that have been ignored by essarraj et al in their contribution essarraj et al relate the genesis of silver ore at imiter to a single regional scale hydrothermal circulation of basinal brines but do not mention preexisting models that emphasize the polyphase character of the mineralization the authors point out the role of triassic evaporitic brines and development of the central atlantic magmatic province as the main ore forming processes that triggered formation of the imiter ag hg ores key evidence for their proposed model is based on the late permian and triassic ages of borisenko et al 2014 that were determined on a

hydrothermal evolution in the formation of silver gold veins in the tayoltita mine san dimas district the tayoltita mine located in the states of durango and sinaloa mexico is a major example of a tertiary volcanic hosted silver gold epithermal vein deposit significant silver and gold values and base metal sulfides as well as most of the vein quartz and accompanying chlorite calcite rhodonite and adularia are restricted to a vertical interval in the veins between approximately 500 and 1 000 m beneath the original surface fluid inclusion studies indicate that ore deposition was from fluids averaging approximately 260 degrees c and was accompanied by some boiling the salinity of the fluid inclusions is estimated at 0 1 m nacl equivalent greater apparent salinities indicated by lower freezing temperatures probably reflect some dissolved co 2 correlation of ag au values with the apparent salinities and with vein mineral paragenesis shows that during ore deposition the fluids evolved in time and space from relatively concentrated to dilute conditions owing to gas loss and possibly some fluid mixing ag au ratio zoning orebody distribution and vein mineral zoning patterns are all consistent with vein formation from fluids flowing predominantly in horizontal flow patterns

estimation of seasonal topographic variation in tidal flats using waterline method a case study in gomso and hampyeong bay south korea abstract morphologic and topographic changes of tidal flats can be key indicators for monitoring environmental changes and sea level rise recently a number of studies have been performed to estimate temporal topographic changes in tidal flats based on the waterline method using a number of remote sensing data that were acquired at different tidal heights however the effect of seasonal variation has not been taken into consideration nor been understood so far in this study 18 scenes of landsat tm and etm data covering the period 2003 2004 and corresponding tidal gauge observation data were used to estimate seasonal topographic variations in two major tidal flats in gomso and hampyeong bay in the southern part of the west sea of south korea using the waterline method our results showed that the summer deposition was dominant in gomso bay with overall average seasonal topographic increase of approximately 18 6 cm in contrast hampyeong bay showed more dominant summer erosion with overall average seasonal topographic subsidence of about 5 0 cm in addition the net overall sedimentation budget was estimated as 6 308 047 m 3 and 2 210 986 m 3 in gomso and hampyeong bay respectively the results also indicates that although both bays of gomso and hampyeong are classified as semi enclosed tidal flat the sedimentary facies caused by formation geometry and sediment type led to different topographic changes the results demonstrate that the amount of seasonal topographic variations is not negligible and are expected to improve the accuracy of topographic change derived by the waterline method

waterline extraction from landsat tm data in a tidal flat a case study in gomso bay korea waterline extraction is potentially one of the most effective satellite remote sensing tools for studying changes in tidal flat environment and coastlines however its application to the study of tidal flats has not been investigated in detail the waterline in a tidal flat in gomso bay korea is characterized and evaluated using 27 sets of landsat thematic mapper tm and earth observing system terra eos terra advanced spaceborne thermal emission and radiometer aster data ground truth data including grain size soil moisture content ground levelling and waterline tracking have been obtained the choice of spectral bands in terms of tidal conditions turned out to play a key role in locating the waterline while the waterlines extracted from near infrared nir short wavelength infrared swir and thermal infrared tir data are commonly reliable on the flood tide the discrepancies between different bands become large on the ebb tide the bands tir nir and swir are in that order decreasingly effective in extracting the waterline while ebb tides are in progress the effect of turbid water on nir can be reduced by a ratioing of nir and the visible band the location of the waterline is also an important factor to consider the discrepancy is largest on the middle tidal flat selection of the proper band for waterline extraction under various conditions is suggested however no single band can accommodate all aspects of the tidal flat environment a schematic model associated with the spectral reflectance of the tidal flat is proposed in which the remnant water scattered on the surface after exposure is emphasized as an additional factor

footprint for frequency domain airborne electromagnetic systems abstractan airborne electromagnetic aem survey often covers hundreds of square kilometers huge amounts of survey data make 2d 3d data inversion very difficult however due to the compact configurations of aem systems the sensitive area for each single survey station is much smaller than the whole survey area which makes it possible to only invert partial survey data the sensitive area is called the footprint based on moving footprint technology the entire survey can be divided into subareas and the data are first inverted individually and then combined to form the inversions of the entire survey area so that the cost for forward and inverse modeling can be vastly reduced contrary to previous electromagnetic em footprints defined only for an em transmitter or for a perfectly conductive earth we defined the frequency domain aem footprint by considering a complete aem transmitter receiver system over an earth with limited conductivity we used the tensor green s function to calculate the seco

multi frequency sar data help improving the monitoring of intertidal flats on the german north sea coast abstract we demonstrate that synthetic apertur radar sar data have great potential to improve an existing monitoring system based on optical data for intertidal flats and to complement the classification of sediments macrophytes and mussels in the german wadden sea multi satellite sar data acquired at different radar bands l c and x band from alos palsar from ers sar radarsat 2 and envisat asar and from terrasar x respectively were used to investigate whether they can be jointly used for crude sediment classification on dry fallen intertidal flats and for detecting benthic fauna such as blue mussel or oyster beds in this respect we show that both multi satellite and multi temporal analyses provide valuable input for the routine monitoring of exposed intertidal flats on the german north sea coast the latter already improving the identification of the spatial extent of mussel oyster beds in addition we demonstrate that high resolution sar is capable of detecting residuals of historical land use in areas that were lost to the sea during major storm surges in the 14th and 17th centuries

on the imaging of exposed intertidal flats by single and dual co polarization synthetic aperture radar abstract we used 26 radarsat 2 and terrasar x single and dual co polarization synthetic aperture radar sar images of a test site on the german north sea coast to investigate the influence of imaging geometry and environmental conditions wind speed water level and vegetation period on the radar return from exposed intertidal flats multi temporal analyses of single vv polarization sar imagery indicate that the surface roughness is more variable at shorter scales responsible for the x band backscatter than at longer scales c band less variation at both radar bands was found in sea grass meadows terrasar x dual co polarization data were used for polarimetric analyses based on a decomposition of the kennaugh matrix whose elements provide information on the total intensity at both co polarizations and on the relative strength of even and odd bounce backscattering at steep incidence angles around 30 the radar backscatter from bare sand flats is similarly strong at both co polarizations while the vertically polarized radar return dominates at higher incidence angles above 40 at low water levels resulting in lower moisture of the sandy sediments strong single bounce radar backscattering was observed while higher water levels and moisture caused weak mixed single and double bounce backscattering apart from the absolute water level its history e g the time and level of the closest low tide must be considered during the vegetation period sea grass meadows cause a stronger increase in horizontally hh polarized radar backscatter along with an increased double bounce backscattering we conclude that the kennaugh element framework has potential to be used for classification purposes in intertidal areas but also that for a full interpretation of the sar imagery the exact topography and the surface roughness have to be known

estimation of surface roughness parameter in intertidal mudflat using airborne polarimetric sar data the coastal zones of the korean peninsula are well known for their large tide ranges and vast expanse of intertidal flats in this paper methods of extracting the roughness of the scattering surface of intertidal mudflats from polarimetric synthetic aperture radar sar data have been investigated the l band nasa jet propulsion laboratories airborne sar data which were acquired in the intertidal zone during pacrim ii korea campaign were used to estimate the roughness of intertidal mudflats surface roughness can be utilized as a useful parameter to monitor the fishery activities in intertidal flats as well as the changes in textural characteristics of surface sediments in order to retrieve roughness parameters such as the rms height and the correlation length of intertidal mudflats three types of roughness inversion algorithms based on the integral equation method iem semiempirical and extended bragg models have been investigated and developed the inversion algorithms based on the iem and semiempirical models can be applied to the dual polarized sar while the extended bragg model based inversion approach is also applicable to the fully polarimetric sar observations results indicate the fully polarimetric approach is more pertinent to monitor geophysical parameters from space than the dual polarimetric approach even if it is possible to reduce the number of unknown surface variables in the specific case of inversion problems

study of the polarimetric characteristics of mud flats in an intertidal zone using c and x band spaceborne sar data abstract the polarimetric characteristics of a mud flat area in the intertidal zone near jiangsu china are analyzed under different environmental conditions using x band and c band spaceborne synthetic aperture radar sar data from the terrasar x tsx and radarsat 2 r2 satellites the dominant scattering mechanisms of different objects including mud flats and aquaculture facilities in the intertidal zone are studied based on the polarimetric target decomposition of fully polarimetric r2 data the polarimetric characteristics of different objects in the intertidal zone are quantitatively compared using the depolarization parameters derived from the r2 data which indicate that tides have different effects on the dominant scattering mechanisms of the mud flats and aquaculture farms furthermore comparisons of the c band and x band polarimetric characteristics of the mud flats and aquaculture farms in the intertidal zone are analyzed by combining the tsx and r2 data the results show that surface scattering is the dominant mechanism of the mud flats whereas different dominant mechanisms occur in the aquaculture areas present during different tides interestingly strikingly similar polarimetric characteristics of mud flats and aquaculture in x band and c band sar are observed and these novel results were achieved through a depolarization analysis based on the tsx and r2 data in synergy