sea ice motion in response to geostrophic winds it is an old rule of thumb that sea ice moves with a speed of about 2 of the surface wind and about 45 to the right of the wind a similar relationship between the ice velocity and the geostrophic wind is examined here it is found that only about half of the long term several month average ice motion is directly related to the geostrophic wind the other half being due to the mean ocean circulation on shorter time scales and in all seasons more than 70 of the variance of the ice velocity in the central arctic ocean is explained by the geostrophic wind within about 400 km of the coasts the geostrophic wind is less successful in explaining the ice motion the spatial variations in ice velocity are also partly explained by the geostrophic wind about half of the variance in the large scale ice vorticity and shear are accounted for on the other hand none of the large scale ice divergence can be explained by the wind the long term average ocean current is estimated by subtracting the share of the ice motion caused by the wind from the total ice motion

discrimination of open water from sea ice in the labrador sea using quad polarized synthetic aperture radar abstract a method to differentiate open water from sea ice using quad polarization c band synthetic aperture radar sar imagery is presented based on the roughness properties of the sea surface scattering facets and the polarization ratio pr between vv and hh polarization backscatter from the sar images in quad polarization sar images the normalized radar cross section nrcs which is linked to sea surface roughness can be used to derive the orientation angle shift and its standard deviation as well as to compute the measured polarization ratio pr an x bragg backscatter model is explored to calculate a theoretical look up table for the polarization ratio as a function of incidence angle dielectric constant orientation angle shift and its standard deviation thus ocean surface backscatter can be identified as open water or sea ice by comparing the measured pr with a theoretical model for pr the proposed method is validated by comparison to collocated optical video images and manual visual interpretations estimates of the size shape and locations of open water from our method are shown to be in good agreement with observed data the overall accuracy of our algorithm is about 96 the classification accuracy for sea ice and open water is about 96 and 94 respectively

provenance constraints from detrital zircon u pb ages in the nw iberian massif implications for palaeozoic plate configuration and variscan evolution detrital zircons from pre orogenic upper ordovician to devonian low grade metasedimentary rocks have been dated by laser ablation inductively coupled plasma mass spectrometry la icp ms to 1 constrain the variations of zircon age populations within the autochthonous sequences of nw iberia 2 compare u pb detrital zircon ages with previous data 3 test the hypothesis of the armorica microplate as a peri gondwanan terrane separated from gondwana the similarity in the ages of detrital zircons found in the palaeozoic samples studied here to those published for the upper proterozoic lower cambrian and lower ordovician sediments of nw iberia argues against the separation of armorica and points to a common source area for all of the palaeozoic detrital formations of nw iberia the west african craton and the surrounding pan african belts la icp ms u pb dating of zircons from a synorogenic flysch preserved in klippen in the core of a syncline establishes a maximum depositional age for this deposit as early namurian this age is also a maximum age limit for thrusting and refolding in this part of the iberian massif correlation of the zircon age populations with published ages confirms the link between the emplacement of the allochthonous complexes of nw iberia and synorogenic sedimentation

sea ice flux in the east greenland current the sea ice export out of the central arctic through the fram strait is a key variable in the arctic climate system satellite data provide the only basis for mapping ice features with a high spatial and temporal resolution in polar regions an automatic drift algorithm has been employed and optimized to monitor the sea ice drift velocity in the greenland sea with avhrr data the combination of the ice drift and the spatial ice distribution provides an insight into the ice transport processes along the coast of greenland the combination with sea ice thickness measurements allows an estimation of the spatial distribution of the sea ice mass flux the seasonal and spatial variability of the mass flux allows further predictions of the meridional melting and freezing processes along the east greenland current this investigation covers the years 1993 and 1994 seasonal and spatial distributions of the sea ice drift were derived the derived absolute values in this study are in good agreement with estimates proposed by other authors

spatial and temporal scales in altimetric variability in the brazil malvinas current confluence region dominance of the semiannual period and large spatial scales two years of geosat data are used to investigate the space and time scales of the mesoscale variability in the brazil malvinas current confluence region the mesoscale activity is highly inhomogeneous and anisotropic the inhomogeneity is characterized by low values of sea level variability in the malvinas current less than 8 cm i e eddy kinetic energy less than 150 cm2 s 2 intermediate values in the brazil current typically 16 cm 800 cm2 s 2 and high values in the brazil malvinas frontal region 30 cm 1700 cm2 s 2 the anisotropy is marked with meridional variances of velocity that are typically three times larger than zonal ones in the region of maximum variability mesoscale variations are dominated by relatively large spatial scales and low frequency fluctuations contrary to similar spectra derived from geosat data over the north atlantic le traon 1991 le traon et al 1990 or over the whole southern ocean chelton et al 1990 there is very little energy at the annual period in the mean spectrum the energy is at least 3 times smaller at the annual period than at the semiannual period or at shorter periods the semiannual signal with length scales of about 400 500 km has a clear northward propagation and is maximum in the frontal region it is probably associated with the semiannual wave that dominates the atmospheric circulation in the southern hemisphere however the mechanism responsible for this semiannual signal in the frontal region remains unclear beyond this dominant semiannual frequency the altimetry derived mesoscale fluctuations exhibit other energetic signals especially signals at periods between 75 and 150 days and spatial scales of 500 600 km with a westward propagation which have characteristics consistent with the dynamics of barotropic rossby waves

computing ocean surface currents from goci ocean color satellite imagery one of the significant challenges in physical oceanography is getting an adequate space time description of the ocean surface currents one possible solution is the maximum cross correlation mcc method that we apply to hourly ocean color images from the geostationary ocean color imager goci over five years since goci provided a large number of image pairs we introduce a new mcc search strategy to improve the computational efficiency of the mcc method saving 95 of the processing time we also use an mcc current merging method to increase the total spatial coverage of the currents proving a 25 increase five year mean and seasonal time average flows are computed to capture the major currents in the area of interest the mean flows investigate the kuroshio path support the triple branch pattern of the tsushima warm current tc and reveal the origin of the tc the evolution of a warm core ring shed by the kuroshio near the northeast coast of honshu japan is clearly depicted by a sequence of three monthly mcc composites we capture the evolution of the kuroshio meander over seasonal monthly and weekly time scales three successive weekly mcc composite maps demonstrate how a large anticyclonic eddy to the south of the kuroshio meander influences its formation and evolution in time and space the unique ability to view short space time scale changes in these strong current systems is a major benefit of the application of the mcc method to the high spatial resolution and rapid refresh goci data

magnetostratigraphy of permian triassic boundary sequences in the cis urals russia no evidence for a major temporal hiatus during the last five years there has been considerable doubt over the age of the continental uppermost permian russian stages the kazanian and tatarian traditionally they have been regarded as late permian but were re dated as middle permian in the 2004 international time scale despite fossil evidence that the tatarian at least is late permian these debated ages are tested by magnetostratigraphic study of five sections spanning the permian triassic boundary ptb of the se urals in the orenburg region of russia the upper permian and lower triassic of this region have a well documented vertebrate fauna whose evolution has a significant bearing on our understanding of the ptb mass extinction event if the tatarian is viewed as mid permian then the late permian in russia is marked by a 9 10 ma stratigraphic gap the palaeomagnetic data yield a distinct series of polarity zones that provide clear local and regional correlation and are readily tied to a recently compiled global magnetostratigraphic record on the basis of this correlation the sampled sections span the upper guadalupian to induan stages without any obvious break so confirming the traditional view that the tatarian is late permian in age anomalies in the magnetic inclination are consistent with sediment compaction inclination shallowing a common phenomenon of red beds but declination anomalies between these sites and elsewhere in russia may suggest localised vertical axis rotation

stratigraphy correlations and palaeogeography of palaeozoic terranes of bulgaria and nw turkey a review of recent data within the alpine tectonic units se of the european variscan orogenic belt in bulgaria and nw turkey several crustal blocks are identified although their contact relations with surrounding units are obscured by alpine events the differences in the succession of events stratigraphy sedimentology and palaeobiogeographical distribution within them permits recognition of the moesian balkan istanbul and zonguldak terranes the moesian terrane corresponds to the pre variscan palaeozoic and neoproterozoic rocks of the moesian microplate in north bulgaria and south romania the balkan terrane in bulgaria incorporates neoproterozoic and palaeozoic sequences in the western balkanides part of the carpathian balkan orogen and another three allochthonous units kraishte central balkanides and strandzhides in nw anatolia in turkey the caledonian basement and ordovician to carboniferous sedimentary succession are divided into the istanbul terrane and the zonguldak terrane with the exception of the moesian terrane in the bulgarian area they all comprise a cadomian basement with relicts of oceanic lithosphere volcanic arc and a continental crust of unknown affinity based on characteristic features within their palaeozoic successions these terranes are correlated with the main terrane assemblages in central and eastern europe it is suggested that they all are of perigondwanan origin but behaved independently while drifting towards laurussia during the early devonian the zonguldak terrane docked to baltica whereas the others were still at similar palaeolatitudes to the central european terranes e g saxo thuringian this was followed by the successive accretion of the moesian terrane to laurussia along the rhenohercynian suture at the end of devonian early carboniferous and of the balkan and istanbul terranes between the early and late carboniferous

synoptic ice motion from avhrr imagery automated measurements versus wind driven theory abstract this note describes the application of a recently elucidated theory of automated sea ice motion detection to avhrr imagery it further seeks to point out the unique ability of avhrr to provide synoptic measurements of sea ice velocity which are useful in validating regional scale ice models the measurements are compared with a simple wind driven theory of ice motion and the results lend support to the linearizing assumptions of the model

fram strait satellite image derived ice motions in order to develop an operational method for the u s navy noaa joint ice center to extract ice velocity vectors from sequential advanced very high resolution radiometer avhrr imagery we have combined the maximum cross correlation mcc method with a spatial filtering technique on the image inferred ice motion vectors we compute the cross correlations between images directly from the image brightness values rather than computing ffts the direct method allows greater flexibility in computational parameter settings and allows one to compute motion vectors near coastlines where irregular windows are required by using a combination of statistical and spatial filters we can then retrieve coherent ice motion vectors in the presence of cloud contaminated imagery a series of six satellite images of the fram strait region from april 1986 was used to compute sea ice motion from pairs of sequential images the resulting ice motion vectors were taken as a representation of the surface flow field derived objectively from the satellite imagery resulting vector motion fields were found to match well with manually tracked vectors for the same images thus verifying the validity of the objective mcc method of computing ice motion these techniques were applied to both the visible and infrared avhrr channels and to images with different spatial resolutions yielding an overall bias accuracy of about 0 5 cm s and standard deviations of about 0 9 cm s the mcc ice motion results were also compared with wind driven numerical model simulations of the region marked differences between the mcc image derived velocities and those from the numerical model were thought to be primarily due to a stronger ocean current than was present in the model

computing coastal ocean surface currents from infrared and ocean color satellite imagery many previous studies have demonstrated the viability of estimating advective ocean surface currents from sequential infrared satellite imagery using the maximum cross correlation mcc technique when applied to 1 1 km resolution advanced very high resolution radiometer avhrr thermal infrared imagery applied only to infrared imagery cloud cover and undesirable viewing conditions gaps in satellite data and edge of scan distortions limit the spatial and temporal coverage of the resulting velocity fields in addition mcc currents are limited to those represented by the displacements of thermal surface patterns and hence isothermal flow is not detected by the mcc method the possibility of supplementing mcc currents derived from thermal avhrr imagery was examined with currents calculated from 1 1 km resolution moderate resolution imaging spectroradiometer modis and sea viewing wide field of view sensor seawifs ocean color imagery which often have spatial patterns complementary to the thermal infrared patterns statistical comparisons are carried out between yearlong collections of thermal and ocean color derived mcc velocities for the central california current it is found that the image surface patterns and resulting mcc velocities complement one another to reduce the effects of poor viewing conditions and isothermal flow the two velocity products are found to agree quite well with a mean correlation of 0 74 a mean rms difference of 7 4 cm s and a mean bias less than 2 cm s which is considerably smaller than the established absolute error of the mcc method merging the thermal and ocean color mcc velocity fields increases the spatial coverage by approximately 25 for this specific case study

surface velocity estimation from satellite imagery using displaced frame central difference equation estimation of surface velocity from satellite imagery with large scale displacement and longer temporal interval is one of the most challenging remote sensing problems in ocean dynamics in this paper a nonlinear inverse model using the displaced frame central difference dfcd equation has been created for estimating velocity in an image sequence iterative equations with gauss newton and levenberg marquardt algorithms are formulated for solving the nonlinear system of equations a unified adaptive framework is developed based on the dfcd equations velocity field modeling a nonlinear least squares model and an algorithm of progressive relaxation of the overconstraint for seeking a flow field in which each vector is consistent with its neighbors a numerical model is used as a benchmark to examine the accuracy of this new technique three sequences of noaa advanced very high resolution radiometer avhrr images taken in the new york bight are also used to demonstrate the performance of the proposed technique the estimated velocity fields are compared with those measured with the coastal ocean dynamics applications radar array the experimental results indicate that the new estimator with the dfcd equation has major improvement over the linear inverse model for the simulation and real avhrr data sets

upper permian vertebrates and their sedimentological context in the south urals russia fossil fishes and tetrapods amphibians and reptiles have been discovered at 81 localities in the upper permian of the southern urals area of european russia the first sites were found in the 1940s and subsequent surveys have revealed many more broad scale stratigraphic schemes have been published but full documentation of the rich tetrapod faunas has not been presented before the area of richest deposits covers some 900 000 km2 of territory between samara on the river volga in the nw and orenburg and sakmara in the sw a continental succession some 3 km thick of mudstones siltstones and sandstones deposited on mudflats and in small rivers flowing off the ural mountain chain span the last two stages of the permian kazanian tatarian the succession is divided into seven successive units of kazanian kalinovskaya osinovskaya and belebey svitas in succession and tatarian age which is further subdivided into the early tatatian urzhumian gorizont bolshekinelskaya and amanakskaya svitas in succession and the late tatarian severodvinian vyazovskaya and malokinelskaya svitas of equivalent age and vyatkian gorizonts kulchumovskaya and kutulukskaya svitas of equivalent age this succession documents major climatic changes with increasing aridity through the late permian the climate changes are manifested in changing sedimentation and the spread of dryland plants and peak aridity was achieved right at the permo triassic ptr boundary coincident with global warming uplift of the urals and extinction of land plants led to stripping of soils and massive run off from the mountains these phenomena have been identified at the ptr boundary elsewhere south africa australia and this may be a key part of the end permian mass extinction the succession of late permian fish and tetrapod faunas in russia documents their richness and diversity before the mass extinction the terminal permian kulchomovskaya and kutulukskaya svitas have yielded respectively some 6 and 13 species of fishes sharks bony fishes lungfishes and 11 and 14 species of tetrapods aquatic amphibians herbivorous and carnivorous reptiles of all sizes up to the hippo sized pareiasaurs and sabre toothed gorgonopsians immediately following the end permian environmental catastrophe earliest triassic faunas consisted only of a few fish taxa and small aquatic tetrapods in low diversity low abundance assemblages

satellite remote sensing of sea ice thickness and kinematics a review observations of sea ice thickness and kinematics are essential for understanding changes in sea ice mass balance interactions between the ice cover and the ocean and atmosphere and for improving projections of sea ice response in a warming climate these parameters are not directly observable with current sensor technology but are derived from satellite altimetry and imagery while there is progress in the retrievals of arctic sea ice thickness from satellite altimetry approaches to address southern ocean ice thickness require additional attention on the other hand procedures to derive sea ice motion from satellite imagery are more mature and better understood and have been employed to produce useful results for more than a decade adequate sampling of sub daily ice motion however remains a challenge generally satellite instruments provide large scale coverage but the frequency of temporal sampling is limited by orbit characteristics in this review i focus on the approaches uncertainties sampling limitations and validation issues associated with the estimation of sea ice thickness and motion i provide a summary of current and anticipated capabilities for monitoring sea ice thickness and kinematics from space the prospects for continuing these measurements into the next decade from a satellite remote sensing perspective are discussed

the performance of four spectral gcms in the southern hemisphere the january and july climatology and the semiannual wave abstract monthly mean sea level pressure slp data from four low resolution spectral gcms ecmwf t21 ccc ncar ccm and gfdl r15 are compared with observations for the southern hemisphere characteristics of the observed southern hemisphere january and july mean mass distribution are i high pressure areas in the subtropics ii a steep meridional gradient at midlatitudes iii a circumpolar trough in the antarctic iv a zonal asymmetry dominated by zonal wave 1 which has an almost complete phase reversal near 40 s v a double westerly wind maximum during the colder part of the year the ccc model reproduces some of these features the ecmwf model the ncar ccm and the gfdl models fail with respect to ii and iii all gcms underestimate the intensity of the stationary eddies none of the models considered reproduces the double westerly wind maximum another marked feature of the southern hemisphere circulation is the semiannual wave that dominates the annual curve of slp at mid and polar lat

ice floe tracker an algorithm to automatically retrieve lagrangian trajectories via feature matching from moderate resolution visual imagery abstract satellite observations of sea ice along marginal ice zones suggest a strong coupling between sea ice transport and the underlying ocean turbulent eddy field moderate resolution imaging spectroradiometer modis satellite imagery spanning over almost two decades of daily observations at a resolution of up to 250 m provides a good resource for deriving long term ocean kinematics from sea ice dynamics in this paper we present a newly developed automatic algorithm to retrieve dynamic measurements of sea ice from these images we describe the methodology by presenting results acquired along the east greenland current ecg for 6 5 weeks in the spring of 2017 during this period our ice floe tracker was used to identify and track ice floes with length scales ranging from 8 to 65 km by effectively filtering atmospheric conditions from modis images ice floes were tracked for up to ten consecutive days and a total of 1061 trajectories were retrieved a southward mean sea ice flow associated with the ecg was observed along with deviations in both direction and magnitude suggesting the effect of an underlying turbulent eddy field the absolute position and tracking errors associated with our method are 255 m and 0 65 cm s respectively each derived from a comparison between manually and automatically identified ice floes going forward our methodology will be employed to process longer time sequences to analyze nonlinear interactions between drifting ice floes and the upper ocean turbulent eddy field in the ecg as well as to investigate other prominent regions of the arctic ocean

advective surface velocities derived from sequential infrared images in the southwestern atlantic ocean abstract sequential infrared satellite images between november 1995 and august 1996 have been used to derive sea surface advective velocities in the southwestern atlantic ocean using the maximum cross correlation mcc technique the infrared images geometrically corrected and accurately registered to a map grid are masked for land and cloud cover the linear displacements of the sea surface thermal features are determined by locating the maximum cross correlation in windowed portions of successive images the advective velocities are estimated for each pair of images based on regular grids incoherent vectors are eliminated from these fields using a statistical method after this a visual inspection by the operator is completed to remove the remaining fictitious vectors the region studied includes the southern brazilian uruguayan and northern argentinian shelves and the neighboring oceanic area known as the brazil malvinas confluence despite the rather complex circulation of this region the advective surface currents calculated by the mcc method are consistent with the shapes of the sea surface temperature features the general patterns of the surface circulation estimated by the mcc agree well with previous studies that used direct measurements hydrographic data and or modeling efforts in the shallower areas of the study region the mcc technique is less applicable due to the predominance in violation of the assumptions of the method of nonadvective processes

flow measurement in streams using video imagery 1 a video imagery technique for making flow measurements in streams and waterways is presented and used to estimate discharge for clear creek near oxford iowa a video camera was used to visualize the flow seeded with tracers measurements of free surface flow velocities were then made using particle image velocimetry piv techniques the velocity measurements were used as input to a hydraulic model which uses kinematic principles conservation of mass to derive three dimensional flow fields for discharge estimation a survey of five channel cross sections over a 7 15 m length of stream were made to define the channel bathymetry for the hydraulic model the average channel width was 5 7 m and the average depth was 0 2 m the discharge estimate using the video technique 0 183 m3 s compares well with the current meter discharge measurement 0 192 m3 s with an estimated standard error of 6 4 the root mean square difference of the depth averaged velocity at the locations of the current meter measurements was 0 032 m s potential applications of the video imagery technique include measurements of flood flows at ungaged sites river monitoring from a remote site and estimation of two and three dimensional flow components

sea ice motion as a drunkard s walk observations of sea ice displacement over short periods of time are used to deduce some statistics of the ice motion over long periods of time the objective is to follow the trajectory of a piece of ice starting at a randomly selected time and location and ending when the ice either melts or leaves the arctic basin trajectories are also followed backward in time to the time and location where the piece of ice was formed statistical properties considered are the age and remaining lifetime of ice in various locations and the probability that ice presently occupying a particular location was originally created or will ultimately melt in certain regions possible applications are to the distribution of pollutants by sea ice and to the design of experiments involving drifting measurement platforms

signature of the brazil malvinas confluence argentine basin in the isotopic composition of planktonic foraminifera from surface sediments we explored the potential to use the stable isotopic compositions of planktonic foraminifera as a proxy for the position of the brazil malvinas confluence bmc in the argentine basin for this purpose we measured the oxygen and carbon isotopic compositions of globigerinoides ruber pink and white varieties measured separately globigerinoides trilobus globigerina bulloides globorotalia inflata and globorotalia truncatulinoides left and right coiling forms measured separately from a latitudinal transect of 56 surface sediment samples from the continental slope off brazil uruguay and argentina between 20 and 48 s lowest oxygen isotopes values were found in g ruber pink followed by g ruber white and g trilobus reflecting the highly stratified near surface water conditions north of the bmc globigerina bulloides was present mainly south of the bmc and records subsurface conditions supporting earlier plankton tow studies globorotalia inflata and g truncatulinoides left and right were both available over the whole transect and calcify in the depth level with the steepest temperature change across the bmc accordingly the 18 o of these species depict a sharp gradient of 2 at the confluence with remarkably stable values north and south of the bmc our data show that the oxygen isotopic composition of g inflata and g truncatulinoides left and right are the most reliable indicators for the present position of the bmc and can therefore be used to define the past migration of the front if appropriate cores are available

sea surface velocities in shallow seas extracted from sequential coastal zone color scanner satellite data sequential images of visible wavelength reflectance from channel 3 540 560 nm of the coastal zone color scanner czcs have been used for computing advective velocities in the eastern english channel using the maximum cross correlation technique the computation method known as matched filtering is widely used by meteorologists and has recently been applied by oceanographers to detect sea surface motion from satellite infrared images provided accurate coregistration of images is achieved by matching ground control points significant correlation is obtained when the technique is applied to czcs data and coherent velocity distributions are obtained for united kingdom shelf waters the residual circulation patterns for the english channel are found to be consistent with previous studies and recent observations

high resolution sea ice motion estimation with optical flow using satellite spectroradiometer data the purpose of this paper is twofold 1 to propose an approach based on optical flow for the estimation of sea ice motion as an accurate dense and computationally efficient alternative to state of the art pattern matching approaches and 2 to investigate the potential of moderate resolution imaging spectroradiometer modis optical satellite data for combined daily and high resolution motion estimation a series of modis image pairs for a selected region in arctic ocean is employed and sparse pairwise correspondences between nonrigid patches are calculated an edge preserving sparse to dense interpolation is applied followed by variational energy minimization to compute the final optical flow a state of the art multiresolution pattern matching method based on phase correlation and normalized cross correlation is also implemented and evaluated for comparison thorough experimentation with different settings of input data preprocessing as well as varying scales of motion is performed the derived motion vectors are compared with coarser resolution operational sea ice motion vector products from combined buoy and microwave satellite data the proposed optical flow approach clearly outperforms the pattern matching method in most cases both in terms of accuracy and motion vector consistency the estimated motion vectors from the modis images highly correlate with the operational vector products in addition modis provides a vector field with spatial resolution two orders of magnitude higher than the operational products that are able to detect significantly smaller sea ice drifts

perito moreno glacier argentina flow estimation by cosmo skymed sequence of high resolution sar x imagery abstract the perito moreno glacier los glaciares national park patagonia argentina ice stream has been investigated using x band sar amplitude images collected from february to december 2009 excluding june at time intervals of 8 and 16 days by the cosmo skymed satellites the high spatial resolution dataset 10 10 km swath 1 m per pixel reveals many details of the glacier surface and the ice velocity fields extracted from sequential image pairs by the maximum cross correlation method cover most of the glacier area the efficiency of the cross correlation method improves with high spatial resolution imagery and the co registration error of the image pair also reduces the glacier motion detected in the period shows variability on the time scale considered evidencing the areas of higher dynamics under different speed regimes

satellite derived maps of arctic and antarctic sea ice motion 1988 to 1994 standard image processing methods applied to 85 5 ghz special sensor microwave imager ssm i data provide previously unseen details about sea ice motion in the arctic and southern oceans means calculated from daily ice motions for 1988 1994 confirm the basic circulation patterns established from drifting stations and buoys but extend these observations to illustrate less well known transport patterns in the arctic coastal zones and sub arctic seas in the antarctic the gridded motion fields show a nearly continuous westward transport along the antarctic coast with well defined regions of exchange between this east wind drift and the antarctic circumpolar current this detailed view of mean ice motion in the southern ocean is unique and presents a comprehensive overview not previously available for antarctic ice motions

enhanced arctic sea ice drift estimation merging radiometer and scatterometer data satellites enable daily and global coverage of the polar oceans and provide a unique monitoring capability of sea ice dynamics sea ice drift maps can be estimated in arctic from several satellite sensors particularly from scatterometers and radiometers this study presents the benefits of combining single drift fields at the same resolution into a merged field built at three and six day lags during winters with a 62 5 km resolution it is shown that combining these drift fields not only increases the reliability of the displacement estimation and the number of estimated vectors to almost a full ice covered area but also expands the time period over which these estimations are reliable from freeze until the melt onset the autumn winter spring sea ice drift fields presented here are systematically produced at institut francais de recherche pour l exploitation de la mer centre d exploitation et de recherche satellitaire the sea ice drift 1992 2011 time series is available and the processing is ongoing these data are available for operational use and for the scientific community

palaeozoic terranes of the balkan peninsula in the framework of pangea assembly abstract the presence of three gondwanan palaeozoic terranes in the basement of the eastern part of the balkan peninsula is revealed by sedimentological palaeoclimatological biogeographical and magnetic data the terranes are from north to south the moesian balkan and thracian terranes they originate from different parts of gondwana and perigondwana regional data indicate an en echelon movement of the moesian and balkan incl thracian terranes from the southern humid zone in the ordovician through the southern arid zone moesian terrane during the devonian and the equatorial zone during the carboniferous to the northern arid zone in the permian devonian convergence brought the moesian terrane and the dobrudgea periphery of palaeo europe into collisional contact the collision between the moesian and balkan incl thracian terranes took place during the late carboniferous and permian and was related to the formation of the variscan orogeny upper palaeozoic molasse sediments blanket a palaeo relief in predominantly continental environments both the collision of the perigondwanan moesian and balkan terranes as well as their accretion to palaeo europe are confirmed by the presence of a megaflora and palynomorphs similar to those in other pangea land areas of similar climatic and hypsometric conditions this study attempts to improve the understanding of the palaeogeographic evolution of the balkan area it further tries to explain the regional processes and stages of formation of pangea

variability and ice production budget in the ross ice shelf polynya based on a simplified polynya model and satellite observations we examined to what degree a simplified polynya model can explain a real polynya based on satellite derived sea ice data in the model the polynya area defined as the frazil ice production region is determined by a balance between the offshore consolidated ice drift and frazil ice production we used daily polynya area ice production and ice drift data derived from amsr e the study area is the ross ice shelf polynya risp which has the highest sea ice production in the southern ocean as a modification of the original model to apply the available satellite data set we introduced the lag time by which produced frazil ice is transported and accumulated at the polynya edge the model represents a half 48 60 of the polynya variability when using a lag time of 1 5 days the frazil ice collection depth at the polynya edge a key parameter in the model is estimated to be 16 cm the expansion of the risp is achieved by ice divergence and the contraction is achieved mostly by ice production both the wind and the remaining components mainly regarded as the ocean current component in the ice divergence are larger in the western part of the risp which explains the larger extent there in the one dimensional frame assuming that the frazil ice produced within the risp transforms into consolidated ice with a thickness of 16 cm the frazil ice production 1 7 103 m2 d 1 within the risp approximately balances the export 1 6 103 m2 d 1 of consolidated thin ice from the risp edge

large scale particle image velocimetry for low velocity and shallow water flows large scale particle image velocimetry lspiv is an extension of quantitative imaging techniques for measurements of water surface velocities using inexpensive standard video equipment the present technical note describes capabilities and limitations of lspiv for low velocity shallow flows measurements in low velocity shallow flume flows were performed to investigate the lspiv sensitivity to seeding density and time interval between successive images the results show that the accuracy of the lspiv technique does not deteriorate as the flow velocity is reduced to as low as 0 015 m s provided an adequate seeding and suitable time difference between images are selected the results suggest that lspiv is well suited for flow fields with small velocities that are often below the limit of detection of most conventional devices

an objective method for computing advective surface velocities from sequential infrared satellite images using cross correlations between sequential infrared satellite images an objective technique is developed to compute advective sea surface velocities cross correlations are computed in 32 x 32 pixel search second image and 22 x 22 template first image windows from gradients of sea surface temperature computed from the satellite images velocity vectors computed from sequential images of the british columbia coastal ocean generally appear coherent and consistent with the seasonal surface current in the region during periods of strong wind forcing as indicated by maps of sea level pressure the image advective velocities are stronger and more coherent spatially and appear to cross surface temperature gradients when winds are weaker the advective velocities correspond better with the infrared temperature patterns suggesting the increased contribution of the geostrophic current to the surface flow velocities determined from coincident near surface drogued 5 10 m buoys positioned every half hour by internal loran c units in mid june show excellent agreement with the image advective velocities in addition conductivity temperature and depth ctd measurements taken during the buoy tracking confirm the homogeneity of the upper 10 m and ctd derived geostrophic currents are consistent with

sea surface velocities from sea surface temperature image sequences 1 method and validation using primitive equation model output an inverse variational finite element model is developed for the purpose of estimating ocean surface velocity fields from sequences of temperature fields the cross isotherm component of the velocity is controlled by a mixed layer integrated formulation of the heat balance the aperture problem imposes additional constraints on the flow field we control the divergence and the vorticity of the horizontal velocity the method is then applied to sequences of sea surface temperature sst fields from a fine mesh numerical simulation over the brazil malvinas confluence region the difference between the actual velocity and the sst inverted velocity is 11 rms in magnitude and 17 rms in direction these differences are analyzed divergence and vorticity are computed the hypothesis of neglecting the source terms made in the formulation of the mixed layer integrated heat balance is verified the sensitivity of the solution to the influence of the constraints is examined perturbations are performed yielding fields of ellipses of covariance we obtain on average 15 uncertainties in magnitude and 25 in direction of the velocity differences between the actual and sst inverted velocities fall into those covariance ellipses except over regions where temperature does not change from one image to the other

time evolution of surface chlorophyll patterns from cross spectrum analysis of satellite color images sequences of coastal zone color scanner czcs images from the offshore region adjacent to vancouver island canada have been analyzed to estimate the time rate of decorrelation of surface phytoplankton chlorophyll pigment patterns in these high latitude high pigment areas czcs derived pigment estimates were lower than those obtained from ship samples by about a factor of 3 their frequency distributions were skewed in opposite directions and subareas of the images often showed a discontinuity in the frequency distribution at a concentration of 1 5 mg m 3 where the algorithm changes czcs bands we selected cloud free subareas that were common to several images separated in time by 1 17 days image pairs were subjected to two dimensional auto spectrum and cross spectrum analysis in an array processor and spectra of squared coherence were formed the squared coherence estimates for several wave bands were plotted against time separation in analogy with a time lagged cross correlation function threshold levels for significant coherence were estimated from many realizations of squared coherence calculated for pairs of synthetic random uncorrelated fields with specified power law behavior 1 5 near the observed range 1 5 2 for wavelengths of 50 150 km significant coherence is lost after 7 10 days and for wavelengths of 25 50 km significant coherence is lost after 5 7 days in both cases offshore regions maintain coherence longer than coastal regions for wavelengths of 12 5 25 km only the offshore regions maintained coherence after 1 day but that was clearly lost after the next time separation of 6 days the implication for the formation of monthly average large scale surface maps to estimate open ocean productivity e g esaias et al 1986 is that all mesoscale patterns 150 km length scale will not be resolved

sea ice circulation in the laptev sea and ice export to the arctic ocean results from satellite remote sensing and numerical modeling sea ice circulation in the laptev sea and ice exchange with the arctic ocean have been studied based on remote sensing data and numerical modeling ice drift patterns for short and long term periods were retrieved from successive okean radar images and special sensor microwave imager data for the winters 1987 1988 and 1994 1995 seasonal and interannual variabilities of ice drift in the laptev sea and ice exchange with the arctic ocean during the period from 1979 to 1995 were studied with a large scale dynamic thermodynamic sea ice model during an average year sea ice was exported from the laptev sea through its northern and eastern boundaries with maximum and minimum export occurring in february and august respectively the winter ice outflow from the laptev sea varied between 251 000 km2 1984 1985 and 732 000 km2 1988 1989 with the mean value of 483 000 km2 sea ice was exported into the east siberian sea mostly in summers with the mean value of 69 000 km2 out of the 17 investigated summers 12 were characterized by sea ice import from the arctic ocean into the laptev sea through its northern boundary magnitude and direction of ice export from the laptev sea corresponded with the large scale arctic ocean drift patterns during periods of prevailing cyclonic or anticyclonic circulation based on a semiempirical method that has been validated with the large scale model and satellite data ice exchange between the laptev sea and the arctic ocean during the period from 1936 to 1995 has been estimated as 309 000km2 with strong interannual variability and no significant trend apparent

multi sensor satellite and in situ measurements of a warm core ocean eddy south of the brazil malvinas confluence region abstract a warm core eddy was detected south of the brazil malvinas falkland confluence bmc region in satellite images of the southwestern atlantic ocean in late 2002 the structure was also sampled by in situ instruments deployed by a ship in 2 days of november 2002 an analysis of satellite data was performed to account for the lifecycle dimension surface temperature surface chlorophyll concentration surface height anomaly and displacement of the eddy since it was detached from the brazil current in september 2002 satellite data were derived from several sources such as the amsr e modis and radar altimeter the structure lasted 64 days at south of the brazil malvinas confluence region later being re assimilated by the brazil current return flow in situ data collected during 2 days showed that the eddy was about 150 m deep 5 5 c warmer and 1 practical salinity unit saltier than adjacent waters the salt anomaly associated to the eddy was estimated as 1 37 10 12 kg while its heat content was 4 24 10 18 j these are typical estimates for eddies present at the bmc region sea surface temperature sst chlorophyll concentration and sea surface height anomaly time series were analyzed for the eddy s center along its trajectory path throughout its lifetime mean translational velocities for the eddy during its lifetime were computed from visual interpretation and by using an adaptation of the maximum cross correlation mcc method on amsr e sst images the overall deviation between the two methods was 26 this suggests that the mcc method has a potential to be applied in monitoring programs to automatically account for the translational velocities of eddies in the bmc region

climatic and biotic changes around the carboniferous permian boundary recorded in the continental basins of the czech republic abstract the paper provides an overview of a several decades long study of transitional carboniferous permian stephanian c autunian sedimentary successions in continental basins of the czech part of the bohemian massif these predominantly monotonous fluvial red beds intercalate with laterally widespread grey to variegated sediments of dominantly lacustrine origin both fossil and climatic records show that apart from a generally known long term climatic shift to drier conditions in early permian the climate oscillated on several time scales throughout the study interval climatic indicators in the red beds part of the succession include palaeosols ranging between red vertisols and vertic calcisols suggesting strongly seasonal dry sub humid climate this is in agreement with the rarity of plant remains which were mostly completely oxidised and only rarely preserved as plant impression in red mudstones or as silicified mostly gymnosperm woods in sandy channel fills silicification instead of coalification was the dominant fossilisation process during red beds deposition even drier possibly semi arid climate may be indicated by spatially and temporarily restricted bimodal sandstones dominated by well rounded quartz grains and interpreted as eolian in origin periods of moist sub humid or even humid climate were accompanied by formation of perennial lakes containing grey laminated mudstones dark grey bituminous mudstones or limestones muddy limestones chert layers or even spatially restricted coals some of them however of economic importance shorter climatic oscillations operating on a scale of tens to possibly hundreds of thousands of years are represented by transgressive regressive lacustrine cycles followed by significant changes in lake water salinity reflected by boron content the fossil record indicates the presence of dryland and wetland biomes in basinal lowlands although their proportions varied significantly as the climate changed during deposition of red beds the alluvial plain was vegetated dominantly by dryland biome assemblages the composition of these assemblages is indicated by fairly common silicified gymnosperm cordaitalean and coniferous woods in sandstone conglomerate fluvial channel bedforms and by poorly preserved impressions of walchian conifer shoots and cordaitalean leaves in associated mudstone intercalations this is in agreement with sub vertical root rhizolites and haloes in calcic vertisols occurrence of wet spots colonised by wetland assemblages is indicated by rather exceptional findings of silicified calamite stems in fluvial red beds associated with gymnospermous woods during the humid intervals parts of the basinal lowlands were occupied by lakes surrounded by broad belts of wetland biome floras during the stephanian c most of these floras were dominated by tree ferns calamites and sub dominant pteridosperms local peat swamps were colonised by lycopsids including sigillaria brardii asolanus camptotaenia and even some lepidodendrid lycopsids in contrast the fossil record of stephanian c dryland floras is rarely preserved in lacustrine sediments the fossil record of autunian lakes however suggests increasing proportions of dryland elements including conifers and peltasperms the response of lacustrine faunas to climatic oscillations around the carboniferous permian transition is less prominent than that of plants the origin of the transition between the local elonichthys sphaerolepis and acanthodes gracilis bio ecozones around the carboniferous permian boundary is impossible to deduce from the existing fossil record

mechanisms for the variation of sea ice extent in the northern hemisphere using daily sea ice data derived from satellite borne sensors and atmospheric data we examined processes controlling the variation of sea ice extent in the northern hemisphere the daily ice motion field was computed from imagery of the defense meteorological satellite program dmsp special sensor microwave imager ssm i for seven winters december to april from 1991 1992 to 1997 1998 by employing the maximum cross correlation method in order to examine mechanisms of the temporal variation of the ice extent we analyzed 50 specified lines across the daily ice edge although a high correlation between the ice motion and the geostrophic wind speed was observed in all the ice edge areas the degree for correlation between the speed of the ice edge displacement and the wind speed varied with region the degree for response of the ice edge speed to the wind speed largely depended upon that of the ice edge speed to the ice motion the following mechanisms controlling the variation of ice extent for regions in the northern hemisphere were anticipated in the barents sea bering sea and the sea of okhotsk the ice extent advances by wind driven ice advection and the daily scale variation of the ice extent were also controlled by the variation in wind speed in contrast the ice extent in the labrador sea and the greenland sea seemed to be considerably affected by oceanographic factors such as the location of the thermal front and was not related to the variation in wind speed the regional difference of the variation mechanism was also reflected in the interannual variation in maximum ice extent

dynamical evaluation of the surface circulation using remote sensing of drifting ice floes an analysis of ice drift from consecutive landsat multispectral scanner images of the same area taken at 24 h interval allowed the calculation of the surface circulation using a dynamical approach comparison between calculated and measured values shows that this method leads to a good approximation of the surface circulation in a region where ice floes are free drifting on the other hand the sole use of the floe drift over time to evaluate the currents leads to results that are far from the measured values tests made using various air and ice drag coefficients and wind speeds and directions for different drift distances show that the error associated with these parameters is small although the values obtained using the numerical data involved considerably more effort and expense the results were not significantly better than those found using photographic products a good approximation of the surface circulation can thus be made using a simple digitization of the floe positions on photographic products application of the methodology to a set of four image pairs led to the recognition of two modes of circulation in southeastern hudson bay in spring 1985 this method can thus become a useful tool for rapid evaluations of surface currents in ice covered areas that can hardly be sampled otherwise

rock physics modeling of unconsolidated sands accounting for nonuniform contacts and heterogeneous stress fields in the effective media approximation with applications to hydrocarbon exploration by treating contact stiffness as a variable one can extend the effective medium approximation used to obtain elastic stiffness of a random pack of spherical grains more specifically we suggest calibrating effective media approximation based on contact mechanics by incorporating nonuniform contact models the simple extension of the theory provides a better fit for many laboratory and field experiments and can provide insight into the micromechanical bonds associated with unconsolidated sediments this approach is motivated by repeated observations of shear wave measurements in unconsolidated sands where observed shear wave velocities are lower than predicted by the hertz mindlin contact theory we present the calibration process for well log data from a north sea well penetrating a shallow gas discovery and a deepwater well in the gulf of mexico finally we demonstrate the benefit of using this model for amplitude variation with angle ava analysis of shallow sand targets in exploration and reservoir studies

a comparison of satellite derived sea ice motion with drifting buoy data in the weddell sea antarctica we compare a satellite derived sea ice motion dataset obtained from the us national snow and ice data center with daily ice drift by drifting buoys between 1989 and 2005 the satellite data were derived from daily composites of passive microwave satellite measurements by means of a cross correlation method and were supplemented with data from visible and thermal channels of the advanced very high resolution radiometer seasonal and interannual variations of the agreement between the two datasets are discussed in addition regional differences in the agreement and correlation coefficients of buoy and satellite derived drift components are analyzed results show that the overall drift regime can be well described by satellite derived drift data but 71 of the retrieved drift velocities are lower than those observed by buoys nevertheless correlation coefficients r between the two datasets are 0 587 for the zonal and 0 613 for the meridional drift component the correlation coefficients between monthly averages of buoy and satellite derived zonal and meridional drift components are on average 25 7 and 16 4 lower in summer october february than in winter march september with the exception of january in january correlation coefficients are about 62 6 zonal and 66 5 meridional lower than in winter furthermore deviations between zonal buoy and satellite derived drift are 80 larger in the second half than in the first half of the year the observed yearly and regional averaged agreement between the two datasets depends strongly on the season when buoy data were collected and on the number of coincident buoy and satellite data which was often very low

analysis of satellite sea surface temperature time series in the brazil malvinas current confluence region dominance of the annual and semiannual periods we study the dominant periodic variations of sea surface temperature sst in the brazil malvinas confluence region from a satellite derived data set compiled by olson et al 1988 this data set is composed of 202 sea surface temperature images with a 4 4 km resolution and extends over 3 years from july 1984 to july 1987 each image is a 5 day composite the dominant signal as already observed by podesta et al 1991 has a 1 year period we first fit a single frequency sinusoidal model of the annual cycle in order to estimate mean temperature amplitude and phase at 159 points uniformly distributed over the region the residuals are generally small less than 2 c the largest departures from this cycle are located either in the brazil malvinas frontal region or in the southeastern part of the region other periods in sst variations are identified by means of periodograms of the 159 residual time series in which the annual cycle has been substracted the periodograms show that a semiannual frequency signal is present at almost every location the ratio of the semiannual amplitude to the annual amplitude increases southward from 0 at 30 s to reach up to 45 at 50 s in the south the semiannual signal creates an asymmetry and the resulting total annual cycle has a cold period winter longer than the warm one summer in the frontal region the annual and semiannual signals have an important interannual variation this semiannual frequency is associated with the semiannual wave present in the atmospheric forcing of the southern hemisphere differential heating over the mid latitude oceans and the high latitude ice covered antarctic continent has been suggested as the cause of this semiannual wave van loon 1967

late permian palynomorph assemblages from ufimian and kazanian type sequences in russia and comparison with roadian and wordian assemblages from the canadian arctic tentative biostratigraphic correlations based on marine faunas have been made by various workers between ufimian and kazanian sequences in their type areas in the volga urals region of russia and roadian and wordian sequences in their type area in texas united states unfortunately palynological correlation between the russian and united states sequences is not possible due to lack of data from the latter however detailed palynological data are available from rocks of roadian and wordian age in the canadian arctic archipelago and therefore indirect correlations are possible palynomorph assemblages from the canadian arctic and other circumpolar areas such as the southern barents sea and greenland are different from those of the ufimian and kazanian russian sequences in their type areas this is likely to be the result of variations in the parent flora in response to significant paleoclimatic differences for example the climate of the volga urals region in late permian times was probably hot and arid whereas that of the canadian arctic barents sea and greenland was cooler and probably more humid

the squirt flow mechanism macroscopic description we introduce a poroelasticity model that incorporates the two most important mechanisms of solid fluid interaction in rocks the biot mechanism and the squirt flow mechanism this combined biot squirt bisq model relates compressional velocity and attenuation to the elastic constants of the drained skeleton and of the solid phase porosity permeability saturation fluid viscosity and compressibility and the characteristic squirt flow length squirt flow length is a fundamental rock property that does not depend on frequency fluid viscosity or compressibility and is determined experimentally we find that the viscoelastic response of many sandstones is dominated by the squirt flow component of the bisq mechanism and that the viscoelastic properties of these rocks can be expressed through a single dimensionless parameter omega r 2 kappa where omega is angular frequency r is the characteristic squirt flow length and kappa is hydraulic diffusivity the biot mechanism alone does not give an adequate explanation of the observed velocity dispersion and attenuation and the viscoelastic behavior of many sandstones

automated extraction of pack ice motion from advanced very high resolution radiometer imagery multiple subarea cross correlations have been computed from visible advanced very high resolution radiometer images of the beaufort sea in an automated technique to detect pack ice motion the computational method is an application of the well known matched filter and consists of subdividing the first image into a set of subareas and correlating each reference subarea against the appropriate region of the second image the correlation functions are processed to determine a set of local maxima which define end point vectors of ice displacements from the subarea centers resulting velocities agree well with estimates of ice movement obtained by manually measuring invariant ice feature displacements the velocity fields show the spatial structures of ice motion over scales of 100 500 km with a high degree of pattern consistency and agreement with simple surface wind driving

mineralogic evidences of a mid paleozoic tectono thermal event in the zonguldak terrane northwest turkey implications for the dynamics of some gondwana derived terranes during the closure of the rheic ocean the zonguldak terrane is a gondwana derived continental microplate along the black sea coast in northwest anato lia it includes a cadomian basement with oceanic and island arc sequences unconformably overlain by siliciclastic rocks of ordovician to middle silurian age after a period of deformation and erosion late lower devonian emsian quartzites and shallow marine limestones unconformably cover middle silurian wenlock graptolitic shales along several cross sections across the unconformity plane the mineralogical characteristics of the paleozoic sedimentary rocks in the zonguldak terrane are studied to check whether this regional unconformity is only of epeirogenic nature or the result of a thermal event in addition to the appearance of kaolinite in devonian units crystal chemical data of illites show a sudden jump at the unconformity plane the b cell dimension values of illites of ordovician silurian units are somewhat higher than those of devonian carboniferous units and show a drastic drop between the silurian and devonian units the new mineralogic data indicate that the pre emsian rocks in the zonguldak terrane experienced a thermodynamo event prior to the emsian transgression this caledonian time event is also reported in east moesian terrane but not noticed in the neighboring istanbul zonguldak and in the west moesian balkan kreishte terranes by this it is suggested that zonguldak and east moesian terranes behaved independently from the istanbul balkan terranes during the closure of the rheic ocean they very likely docked to laurussia during emsian by strike slip faults and remained thereon at its platform margin where the middle late devonian shallow platform conditions were fol lowed by fluvial lagoon and delta conditions and deposition of coal during late carboniferous

relationship between sea ice motion and geostrophic wind in the northern hemisphere this paper presents maps showing the relationship between sea ice motion derived from defense meteorological satellite program dmsp special sensor microwave imager ssm i imagery and the geostrophic wind in the northern hemisphere for seven winters 1991 92 1997 98 the sea ice motion is highly correlated with the geostrophic wind except for some coastal regions overall the direction of the ice motion is nearly parallel to the wind an obvious contrast between seasonal ice zones and the interior of the arctic is observed in the speed reduction factor ratio of ice speed to wind speed which is probably caused by the spatial variation of internal ice stress surface ocean currents are also derived by subtracting the wind effect from the ice motion

sea ice motion from low resolution satellite sensors an alternative method and its validation in the arctic 1 the retrieval of sea ice motion with the maximum cross correlation mcc method from low resolution 10 15 km spaceborne imaging sensors is challenged by a dominating quantization noise as the time span of displacement vectors is shortened to allow investigating shorter displacements from these instruments we introduce an alternative sea ice motion tracking algorithm that builds on the mcc method but relies on a continuous optimization step for computing the motion vector the prime effect of this method is to effectively dampen the quantization noise an artifact of the mcc it allows for retrieving spatially smooth 48 h sea ice motion vector fields in the arctic strategies to detect and correct erroneous vectors as well as to optimally merge several polarization channels of a given instrument are also described a test processing chain is implemented and run with several active and passive microwave imagers advanced microwave scanning radiometer eos amsr e special sensor microwave imager and advanced scatterometer during three arctic autumn winter and spring seasons ice motion vectors are collocated to and compared with gps positions of in situ drifters error statistics are shown to be ranging from 2 5 to 4 5 km standard deviation for components of the vectors depending on the sensor without significant bias we discuss the relative contribution of measurement and representativeness errors by analyzing monthly validation statistics the 37 ghz channels of the amsr e instrument allow for the best validation statistics the operational low resolution sea ice drift product of the eumetsat osi saf european organisation for the exploitation of meteorological satellites ocean and sea ice satellite application facility is based on the algorithms presented in this paper

large scale drift of arctic sea ice retrieved from passive microwave satellite data a method of determining the large scale sea ice drift using 85 5 ghz special sensor microwave imager data are presented a cross correlation method is applied to sequential images of gridded data covering the entire arctic individual correlation results are validated with ice velocities derived from buoy data the satellite derived mean drift values and the variabilities of the ice drift correspond closely with the buoy data similarly time series of buoy data and associated satellite data are in good agreement even over large time periods an example of a satellite retrieved 3 day mean drift field demonstrates the potential of the method for providing large scale ice circulation patterns mean drift fields of the winter periods 1987 1988 and 1992 1993 indicate a considerable interannual variability of the sea ice drift pattern in the arctic ocean the arctic region is divided into seven larger areas and the area flux between these regions has been derived the kara sea and the laptev sea show the largest area ice export with 0 02 and 0 015 km 2 s 1 respectively the central arctic export through fram strait amounts to 0 12 sv during the winter of 1992 1993 with a maximum of 0 15 sv in january

measuring surface currents in lakes with high spatial resolution thermal infrared imagery 1 high spatial resolution thermal infrared satellite images acquired 38 minutes apart from landsat etm and aster were used to measure the surface currents and circulation in lake tahoe california nevada usa mean currents of 5 10 cm s were measured with maximum currents approaching 35 cm s the eastward transport of an upwelling surface jet was clearly apparent with 15 30 cm s currents three gyres were evident in the vector fields the satellite image derived surface currents and circulation patterns are consistent with surface drifter measurements acquired during a different period these results modify the findings of an earlier study using 1 1 km avhrr imagery which concluded there were two counter rotating gyres in the opposite sense to the two dominant large gyres measured in this study the high spatial resolution and small time separation allow the surface currents and general circulation in lakes and coastal environments to be accurately quantified using the maximum cross correlation method

increase and decrease of sea ice area in the sea of okhotsk ice production in coastal polynyas and dynamic thickening in convergence zones 1 this paper examines the production and reduction of sea ice area in the sea of okhotsk analyses were carried out for 10 winters december april from 1991 1992 to 2000 2001 using daily data of sea ice velocity and concentration derived from images of the defense meteorological satellite program dmsp special sensor microwave imager ssm i first we mapped sea ice divergence which was calculated from the daily ice velocity field in the case of offshore winds high divergence was observed along the coastline while there existed a broad convergence area with inshore winds next we examined local changes in an area of sea ice as in the case of ice divergence ice production and reduction are strongly controlled by wind direction we found that a large amount of sea ice was produced in coastal areas under offshore wind conditions the geographical distribution of the ice production area agrees well with that of the well known coastal polynya areas our estimation shows that 8 7 105 km2 yr 1 of sea ice is produced in the northern coastal area and 3 7 105 km2 yr 1 in the sakhalin coastal area in contrast 7 4 105 km2 yr 1 of the ice area disappeared in shantarskiy bay this reduction of ice area is mainly caused by dynamic deformation of existing ice forming rafted ice or pressure ridges this dynamic deformation plays an important role not only in the reduction of okhotsk sea ice area but also in the thickening of ice

elastic property changes in a bitumen reservoir during steam injection the hangingstone steam assisted gravity drainage sagd operation of japan canada oil sands limited jacos is approximately 50 km south southwest of fort mcmurray in northern alberta canada jacos started the operation in 1997 and has produced bitumen since 1999 the oil sands reservoirs in hangingstone occur in the lower cretaceous mcmurray formation and are about 300 m in depth the sedimentary environments are fluvial to upper estuarine channel fill and the oil sands reservoirs correspond to vertically stacked incised valley fill with very complex vertical and horizontal distribution

ocean surface currents from avhrr imagery comparison with land based hf radar measurements we focus on inverting the surface temperature or heat equation to obtain the surface velocity field in the coastal ocean and compare the results with those from the maximum cross correlation mcc technique and with the in situ velocity fields measured by the rutgers university coastal ocean dynamics radar codar when compared with codar fields velocities from the heat equation and mcc have comparable accuracies but the heat equation technique better resolves the finer scale flow features we use the results to directly calculate the surface divergence and vorticity this is possible because we convert the traditionally underdetermined heat inversion problem to an overdetermined one without constraining the velocity field with divergence vorticity or energy statements because no a priori assumptions are made about the vorticity it can be calculated directly from the velocity results the derived vorticity field has typical open ocean magnitudes 5 times 10 5 s and exhibits several structures a warm core ring gulf stream filament and a diverging flow consistent with the types of flows required to kinematically deform the sea surface temperature patterns into the observed configurations

dopscat a mission concept for simultaneous measurements of marine winds and surface currents a radar scatterometer operates by transmitting a pulse of microwave energy toward the ocean s surface and measuring the normalized per unit surface radar backscatter coef cient r8 the primary application of scatterometry is the measurement of near surface ocean winds by combining r 8 measurements from different azimuth angles the 10 m vector wind can be determined through a geophys ical model function gmf which relates wind and backscatter this paper proposes a mission concept for the measurement of both oceanic winds and surface currents which makes full use of earlier c band radar remote sensing experience for the determination of ocean currents in particular the novel idea of using two chirps of opposite slope is introduced the fundamental processing steps required to retrieve surface currents are given together with their associated accuracies a detailed description of the mission proposal and comparisons between real and retrieved surface currents are presented the proposed ocean doppler scatterometer can be used to generate global surface ocean current maps with accuracies better than 0 2 m s at a spatial resolution better than 25 km i e 12 5 km spatial sampling on a daily basis these maps will allow gaining some insights on the upper ocean mesoscale dynamics the work lies at a frontier given that the present inability to measure ocean currents from space in a consistent and synoptic manner repre sents one of the greatest weaknesses in ocean remote sensing

late permian tatarian fluvio lacustrine successions in nw anatolia zonguldak terrane turkey palaeogeographic implications late permian fluvio lacustrine successions of the cakraz formation in the zonguldak terrane between the regions of akcakoca and eregli were investigated in order to describe the litho and biostratigraphic properties and explain the depositional environment the studied succession with black dark grey to greenish grey shales siltstones and limestones is named the alapli member to distinguish it from the classical red clastic successions which are tentatively named the eregli member of the cakraz formation the organic rich black shales mudstones and limestones of the alapli member yielded palynological assemblages suggesting a lopingian tatarian age the lack of any marine macro or microfossils the fine grained character of the lithofacies with abundant plant material and the association of poorly sorted conglomerates in the middle part of the succession indicate possible deposition in a broad range of fluvial and lacustrine environments successions of similar age and depositional environment are known from the east european variscan belt in bulgaria and romania common successions were also developed in actively extending shallow marine platforms on the nw palaeotethyan margin at the end of the permian period

disruption of playa lacustrine depositional systems at the permo triassic boundary evidence from vyazniki and gorokhovets on the russian platform abstract permo triassic sections at vyazniki and gorokhovets provide evidence on terrestrial events at or close to the permo triassic boundary the time of the largest ever mass extinction the sedimentary succession records the overrun of a muddy playa lacustrine depositional system by major channel belts transporting sand grade sediments biostratigraphy of sections at vyazniki and gorokhovets zhukov ravine shows that this event occurred either at the very end of the permian or 8 m above in the sections the timing and nature of this event which records increased sediment flux from the ural mountains is closely comparable with that from the southern uralian foreland basin the vyazniki and gorokhovets sections are 800 km from the mountain front and in a separate depositional basin which strengthens the case that increased sediment flux from the urals at the permo triassic boundary is related to devegetation of upland catchments increasing sediment yield and a switch toward low frequency but high magnitude discharge events increasing sediment delivery the interbedding of fluvial and aeolian deposits provides further evidence for climatic instability and extremes in the early triassic supplementary material detailed reports on the ostracodes and fossil fish remains from the zhukov ravine sections are available at http www geolsoc org uk sup18402

spreading dynamics of small river plumes off the northeastern coast of the black sea observed by landsat 8 and sentinel 2 abstract we use near simultaneous ocean color satellite imagery from nasa s landsat 8 and esa s sentinel 2 missions to reconstruct surface currents along the northeastern shore of the black sea and study the spread of a small river plume formed in this area several times a year landsat 8 and sentinel 2 satellites both pass over the study area within a time interval of

sea surface velocities from visible and infrared multispectral atmospheric mapping sensor mams imagery high resolution 100 m sequential multispectral atmospheric mapping sensor mams images were used to calculate sea surface velocities from the advection of visible and thermal surface features using maximum cross correlation mcc and subjective techniques the visible gradient image velocities agreed well with the subjective motion while the infrared channel performed best without computing gradients

resolution of the ocean wave propagation direction in sar imagery there is an inherent 180 degrees ambiguity in the derived wave propagation direction when using conventional spectral analysis techniques on standard synthetic aperture radar sar image products three different techniques are successfully used to resolve this ambiguity in propagation direction using a single pass of airborne sar data the fact that the sar is characterized by a large time bandwidth product is used to advantage a sequence of individual looks extracted from the doppler spectrum represents images of the scene collected at a sequence of discretely delayed intervals of time the techniques utilized include cross correlation based motion analysis of a pair of looks phase weighting based upon a pair of looks and the ocean wave dispersion relation and a three dimensional spectral analysis the phase weighting technique is also demonstrated for a seasat sar scene

tracking oceanic currents by singularity analysis of microwave sea surface temperature images in the recent years the power of employing singularity analysis of scalar variables to perform pattern recognition in complex images has been evidenced this approach is particularly useful when the image under study corresponds to a scalar variable submitted to a turbulent flow because in that case the arrangement of singularity manifolds corresponds to the multifractal hierarchy from the underlying turbulent flow in this paper we will show how this intimate connection between image processing and physics when applied to microwave sea surface temperature images allows to uncover global circulation patterns in the ocean at a daily basis with the resolution of 1 4 of degree using this technique details not evidenced in the non processed image are revealed the emerging patterns provide a description of the global oceanic currents much richer than the usual global circulation scheme in particular instabilities eddy generation and filamentation are distinctly identified a pattern extraction of this kind is useful in order to measure and track mesoscale oceanic phenomena opening the way to many operational and reanalysis applications

an inverse model for seasonal circulation over the southern brazilian shelf near surface velocity from the heat budget abstract an inverse model was developed of the seasonal upper layer circulation in the region adjacent to the coast of southern brazil between 30 and 35 s 50 and 55 w near the boundary of the brazil malvinas confluence in this region there are no in situ data on circulation while a large array of data on sea surface temperature and surface heat fluxes acquired through the last 30 years is available the model is based on the joint analysis of observed seasonal changes of sst along with observed fields of insolation and surface heat fluxes from the equation of heat conservation integrated over the variable depth of the mixed layer the residual flux fields required to explain the observed temperature changes between seasons were computed generally this residual flux accounts for advection diffusion and entrainment diffusion has been neglected based on scaling estimates of term sizes while entrainment was parameterized through observed changes of the mixed layer depth with the assumption that

computing advective velocities from satellite images of sea surface temperature a method of employing sequential satellite images of sea surface temperature sst patterns to estimate surface advective current velocities is described sst images are obtained by processing data received twice daily from the advanced very high resolution radiometer the current velocities are estimated by applying a maximum cross correlation mcc technique on two time lapsed images the mcc technique involves computing matrices of cross correlation coefficients and identifying correlation peaks a two stage multilevel statistical test over two dimensional correlations is developed for determining the relative significance levels of velocity estimates the test also identifies areas where the mcc technique cannot be effective aspects of implementation and limitations of the mcc technique for computing current velocity are also discussed advective velocity fields computed through mcc for the chatham rise area in new zealand extending from 40 5 degrees s 173 5 degrees e to 49 degrees s 178 degrees w show good agreement with the known geostrophic flow patterns in this area

comparison of velocity estimates from advanced very high resolution radiometer in the coastal transition zone two methods of estimating surface velocity vectors from advanced very high resolution radiometer avhrr data were applied to the same set of images and the results were compared with in situ and altimeter measurements the first method used an automated feature tracking algorithm and the second method used an inversion of the heat equation the 11 images were from 3 days in july 1988 during the coastal transition zone field program and the in situ data included acoustic doppler current profiler adcp vectors and velocities from near surface drifters the two methods were comparable in their degree of agreement with the in situ data yielding velocity magnitudes that were 30 50 less than drifter and adcp velocities measured at 15 20 m depth with rms directional differences of about 60 these differences compared favorably with a baseline difference estimate between adcp vectors interpolated to drifter locations within a well sampled region high correlations between the avhrr estimates and the coincident geosat geostrophic velocity profiles suggested that the avhrr methods adequately resolved the important flow features the flow field was determined to consist primarily of a meandering southward flowing current interacting with several eddies including a strong anticyclonic eddy to the north of the jet incorporation of sparse altimeter data into the avhrr estimates gave a modest improvement in comparisons with in situ data

heavy oil sands measurement and rock physics modeling abstractheavy oil reservoirs are important alternative energy resources to conventional oil and gas reservoirs however due to the high viscosity of heavy oil much production of heavy oil reservoirs involves injecting steam and determining the temperature distribution is significant for production to do this time lapse inversion is commonly used to derive the change of the oil sand properties during steam injection and rock physics models are used to link the properties and temperature many people have done research on simulating variations of the oil sand properties with temperature however the previous models fail to adequately represent our experimental data and they overestimate their values the errors between previous models predictions and measurements are quite large especially at low temperatures to study the oil sand properties we first measured eight oil sand samples including five presteam samples and three poststeam samples and we experimentally quantified the pressure sensitiv

thermohaline fronts and baroclinic flow in the argentine basin during the austral spring of 1984 thermohaline fronts structure and baroclinic flow in the central argentine basin are investigated on the basis of a 1984 field experiment the brazil current after initial overshoot meanders northeastward toward subtropical latitudes with speeds of the order of 0 3 m s 1 the meanders have a wavelength of about 400 km and an amplitude of 200 km brazil current signatures as expressed by dynamic height are recognizable to depths of several kilometers the brazil and antarctic circumpolar currents do not meet in the central argentine basin to form common eastward flow as was expressed in classical descriptions but instead diverge sharply near 42 w this is seen also in the trajectories of satellite tracked drifters the region between the currents is marked by cyclonic and anticyclonic eddies strong thermohaline fronts accompany the boundaries of these currents the brazil current and subantarctic fronts are well separated in the central basin brazil current density fronts are deep and extend from the surface to 3000 m while the associated temperature and salinity fronts are intermittent over this depth interval temperature fronts virtually vanish at the interface between the antarctic intermediate water and the north atlantic deep water salinity fronts reverse their polarity beneath the core of the former at depths between 3000 and 4000 m abyssal temperature and salinity fronts are observed which are largely density compensating at the subantarctic and cold core eddy fronts horizontal temperature and salinity gradients in the upper mixed layer compensate each other in such a way that no density front is found deep subpycnocline mixed layers occur in the poleward lobes of the brazil current during austral spring suggestive of previous winter convection

error analysis and assimilation of remotely sensed ice motion within an arctic sea ice model new sea ice motion fields available from remotely sensed data are potentially useful for assessing and improving models of the polar ice pack here we investigate the error characteristics of the observed ice motions relative to drifting buoys and a dynamic thermodynamic ice model a data assimilation approach is then used to assess the potential of the motion data for reducing model biases as well as the potential of the model to serve as an interpolation tool to generate improved ice motion data sets special sensor microwave imager ssm i derived and model simulated ice motions for the years 1988 through 1993 are compared with ice displacement observations from drifting buoys variability and biases are summarized for seasonal and regional means ssm i motions are assimilated into the model using an optimal interpolation method that accounts for the modeled and ssm i motion error variances and the number and distribution of the ssm i motions modeled and ssm i derived motions are found to have comparable mean errors with some notable regional and seasonal differences assimilation substantially reduces the error standard deviation and improves the correlation of the simulated motions relative to the buoy observations but some biases remain in the model framework used here assimilation of the ssm i data substantially alters average ice thickness in some regions of the arctic and affects ice mass outflow through the fram strait but has a small effect on mean ice concentration the assimilation yields an increase in the spatial and temporal variability in ice deformation the observations are particularly suited for improving the simulation of specific synoptic events where substantial differences can occur between simulated and observed ice transport

fundamentals of seismic rock physics during the past 50 years or so tremendous progress has been made in studying physical properties of rocks and minerals in relation to seismic exploration and earthquake seismology during this period many theories have been developed and many experiments have been carried out some of these theories and experimental results have played important roles in advancing earth sciences and exploration technologies this tutorial paper attempts to summarize some of these results

the subantarctic and polar fronts in relation to deep water masses through the southwestern atlantic the two principal fronts within the antarctic circumpolar current acc the subantarctic front saf and the polar front pf are investigated with respect to their spatial patterns and relations to deep water masses from the northern drake passage to the western and southern argentine basin observations from four recent cruises in adjoining and overlapping regions are supplemented with satellite infrared imagery and trajectories from surface drifters east of drake passage the width of the polar frontal zone pfz increases rapidly when the saf turns sharply northward as a part of the falkland malvinas current while the pf remains oriented mainly toward the northeast found within this region of the pfz are mesoscale eddies the upper layers of which consist of subantarctic mode water from the pacific the contrasts in upper layer water properties that identify the saf can be traced the entire length of the falkland current to the brazil falkland confluence zone and then southward to the southern argentine basin there the saf turns eastward and later but perhaps not always merges with the pf north of ewing bank to form a single intense current core strongly influenced by bottom topography at times this eastward current loops southward through a gap in the falkland ridge into the georgia basin thereby supplying relatively warm and salty subantarctic water to the antarctic zone east of the gap the two fronts become separated and are once again distinct features in the vicinity of the islas orcadas rise at depth within drake passage and the western scotia sea the saf and pf are not lateral boundaries between distinct water masses but are instead identified by enhanced vertical displacements of property isopleths with the northward turn of the saf east of drake passage a thick layer of circumpolar deep water cdw is advected over the falkland plateau into the argentine basin there it is joined by waters entering the argentine basin via a deep spreading route through the georgia basin denser cdw deep water from the weddell sea and episodically deep water from the southeastern pacific ocean together these waters form a northward flow off the patagonian shelf that extends from the sea surface to the bottom most of which turns back toward the south with the falkland current return also flowing south along the seaward side of the falkland current return well away from the western boundary is the main core of north atlantic deep water nadw detatched masses of nadw are observed within the cdw at the western boundary as well as within the acc south of the saf in the south central argentine basin

sea ice tracking by nested correlations spatial differences in sea ice displacement affect ice stress ice production and the mass balance of the ice cover our concepts about the spatial structure of this field have been undernourished because of a paucity of data with high spatial detail and because of the tedium of extracting such measurements from images manually a method is described that measures displacements from synthetic aperture radar digital imagery with fine spatial resolution and does so fully automatically many small areas of ice common to two images are identified by correlating the two images the strategy is to acquire a crude displacement field first from highly averaged images and to refine this field with images of successively higher resolution the median discrepancy between automatically and manually measured displacements is three pixels 0 075 km the algorithm operates successfully on compact ice with large floes and modest rotation rates we believe it will prove applicable to most of the arctic ice cover throughout the year

sea ice motion and open water area at the ronne polynia antarctica synthetic aperture radar observations versus model results 1 this study deals with observations and simulations of the evolution of coastal polynias focusing on the ronne polynia we compare differences in polynia extent and ice drift patterns derived from satellite radar images and from simulations with the finite element sea ice ocean model employing three atmospheric forcing data sets that differ in spatial and temporal resolution two polynia events are analyzed one from austral summer and one from late fall 2008 the open water area in the polynia is of similar size in the satellite images and in the model simulations but its temporal evolution differs depending on katabatic winds being resolved in the atmospheric forcing data sets modeled ice drift is slower than the observed and reveals greater turning angles relative to the wind direction in many cases for the summer event model results obtained with high resolution forcing are closer to the drift field derived from radar imagery than those from coarse resolution forcing for the late fall event none of the forcing data yields outstanding results our study demonstrates that a dense 1 3 km model grid and atmospheric forcing provided at high spatial resolution 50 km are critical to correctly simulate coastal polynias with a coupled sea ice ocean model

velocity observations of the california current derived from satellite imagery 1 this research examines the potential of ocean velocity observations generated from the maximum cross correlation technique mcc applied to thermal infrared imagery to capture the total current at a high sampling rate especially in the nearshore region allowing for a novel view of the california current comparison of 12 years of weekly ocean velocity fields derived from the mcc method with velocity observations from drifting buoys reveals strong correspondence between the data sets the mcc method however is able to produce over 10 times the number of observations comparison of mcc velocities with geostrophic velocities from altimetry demonstrates differences that suggest ageostrophic currents in the mcc observations that are likely wind driven the time averaged mean velocity field from mcc observations reveals strong offshore jet like features that extend off of coastline promontories eddy statistics from the mcc velocity observations indicate dramatically different dynamics in the nearshore and offshore regions differences in spatial statistics derived from the mcc observations compared to previous studies of the region are attributed to wind driven currents in the observations that can dominate the variability of the current in the nearshore region