comparison of magnetic hysteresis parameters of unremagnetized and remagnetized limestones for white magnetite bearing mesozoic pelagic limestones from italy which carry a primary magnetization the values of mrs ms and hcr hc generally lie in the pseudo single domain psd field of the day et al 1977 plot the logarithmic plot of mrs ms against hcr hc gives a straight line r 0 814 with slope and intercept close to the empirical mixing line of parry 1982 for single domain sd and multidomain md magnetite for one of the white pelagic limestone formations maiolica formation samples with hysteresis ratios closer to the md field display increased paramagnetic susceptibility and are from the upper part of the formation characterized by increased detrital clay we therefore associate the increased md magnetite with increased detrital influx for pinkish and reddish varieties of the italian pelagic limestones the presence of hematite is manifest by high saturation fields a wide range of hcr hc and wasp waisted hysteresis loops attributed to the mixing of magnetite and high coercivity authigenic hematite the hysteresis ratios for a collection of paleozoic and mesozoic remagnetized magnetite bearing limestones from britain nevada alaska and the appalachians lie mainly outside the psd field and appear to follow a power law trend following jackson et al 1993 the high values of hcr hc and the characteristically wasp waisted hysteresis loops can be interpreted in terms of a fine grained subspherical high coercivity sd magnetite mixed with a high proportion of superparamagnetic magnetite the slope and intercept of the power law relationship for mrs ms and hcr hc in the remagnetized limestones are distinct from those observed for the italian limestones and may provide a means of fingerprinting magnetite of primary as opposed to diagenetic origin

late paleozoic remagnetization in limestones of the craven basin northern england and the rock magnetic fingerprint of remagnetized sedimentary carbonates samples of lower carboniferous chatburn and pendleside limestones collected from 27 sites in the craven basin northern england carry a syn hercynian remagnetization residing in magnetite the paleomagnetic directions are all of reversed polarity consistent with a kiaman superchron remagnetization the partially 62 tilt corrected mean direction has the minimum correlation statistic implying a synfolding magnetization the resulting pole appears to be late carboniferous in age and there is no indication of any magnetization component that predates the remagnetization event the magnetization appears to be of the same type as the synfolding remagnetizations documented in several appalachian carbonate units jackson 1990 reported that remagnetized appalachian carbonates have distinctive hysteresis properties and we have obtained similar hysteresis loops from remagnetized paleozoic carbonates from the craven basin england the great basin nevada alaska and new york state the hysteresis loops are all wasp waisted and yield highly anomalous hysteresis ratios compared to data from synthetic or typical magnetite bearing samples in contrast unremagnetized limestones from italy show hysteresis behavior which is more typical for magnetite bearing rocks channell and mccabe this issue these results suggest that remagnetization in magnetite bearing carbonates can be readily detected on the basis of hysteresis properties prior to a full scale paleomagnetic investigation

domain observations of the magnetic phases in volcanics with self reversed magnetization the temperature dependence of magnetic domain pattern in titanomagnetite and titanohematite of self reversing andesites from the 1985 eruption of the nevado del ruiz volcano colombia has been observed using the bitter technique during heating cooling cycles in the laboratory the natural remanent magnetization loses the self reversal properties between 110 c and 180 c the titanohematite domains disappear in the same temperature interval large grain regions without visible colloid contrast are observed between room temperature and 180 c utilizing the high resolution of a magnetic force microscope it is found that these regions contain either domains with wall spacing of about 3 m or a buckling pattern along the phase boundary between a titanomagnetite and a titanohematite grain but within the titanohematite a 2 m wide chemically different domain has been observed it has a higher iron content than the main titanohematite the two titanohematite phases represent two phases with higher curie temperature tc but lower spontaneous magnetization ms and lower tc but higher ms respectively negative interaction between these phases is called upon to explain the self reversing mechanism

a global view of martian surface compositions from mgs tes thermal emission spectrometer tes data from the mars global surveyor mgs are used to determine compositions and distributions of martian low albedo regions two surface spectral signatures are identified from low albedo regions comparisons with spectra of terrestrial rock samples and deconvolution results indicate that the two compositions are a basaltic composition dominated by plagioclase feldspar and clinopyroxene and an andesitic composition dominated by plagioclase feldspar and volcanic glass the distribution of the two compositions is split roughly along the planetary dichotomy the basaltic composition is confined to older surfaces and the more silicic composition is concentrated in the younger northern plains

mapping of spectral variations on the surface of mars from high spectral resolution telescopic images abstract we analyze a high spectral resolution r 200 visible and near infrared 0 44 1 02 m telescopic spectral image of mars to explore surface material variations across the observed face of the planet which is centered on sinus meridiani two independent analysis methods are employed linear mixture modeling and supervised spectral pattern classification with an artificial neural network four endmember type regions are identified with linear mixing further refinement is achieved with the nonlinear neural network classification algorithm separating eight units of geological significance differences in spectral features among the mapped units are characterized among the medium to high albedo units northern lowlands typified by chryse planitia show far less evidence of bulk crystalline hematite than western arabia or any other highland regions the relationship of these bright units to the globally distributed aeolian dust is not yet clear within our image low albedo regions with the most pronounced crystalline hematite signature primarily correlate with the classic dark regions with the exception of acidalia planitia spectral evidence for pyroxenes also correlates well with most of the classic low albedo regions but again acidalia planitia is the major exception significant spectral anomaly is also found in an equatorial region deucalionis regio a companion paper in this issue discusses the soil properties of deucalionis our data and analysis support a compositional trend that is consistent with the global geologic crustal dichotomy of mars namely that the younger northern lowlands contain less bulk crystalline hematite than southern highlands

domain size closure domains and the importance of magnetostriction in magnetite abstract previous micromagnetic calculations invoking magnetostatic exchange and crystalline anisotropy energies predict about an order of magnitude more domains in magnetite than have experimentally been observed domains observed on magnetite by the magneto optic kerr effect are of similar size as previously observed ones by the bitter technique simple but quite accurate domain calculations show that for rectangular parallelepipeds of magnetite it is the closure four domain configuration that should be of lowest energy for all multidomain grain sizes unless magnetostrictive energies are considered for the observed domain pattern it is shown that the domains themselves must carry significant magnetoelastic energies

seasonal exchanges of the kuroshio and shelf waters and their impacts on the shelf currents of the east china sea previous in situ observations and modeling studies have indicated that through mass and momentum exchanges across the shelf edge the kuroshio can significantly influence the shelf currents of the east china sea ecs here instead of localized observations this study uses 25yr of drifter data supported by satellite and other data to identify seasonal cross shelf exchanges along the entire shelf edge the authors show that kuroshiomeandersonshorefromfalltowinterandoffshorefromspringtosummer withthelargestamplitude northeast of taiwan the influence is limited to the shelf edge when the kuroshio meanders offshore in spring and summer by contrast strong onshelf intrusions and cross shelf exchanges occur when the kuroshio meanders onshore in fall and winter drifters intrude onshelf northeast of taiwan and spread as far north as 308n against the strong northeasterly wind the forcing on the shelf is identified as a northward downsloping of the sea level that is steepest north of taiwan at 258 288n but which is 3 times weaker farther north the vorticity budget computed from a numerical model indicates that intrusion during fall andwinter is primarily a result of balancebetweenonshelfadvectionofambientpotentialvorticityandvorticityproductionbythealong isobath pressure gradient acting on the changing mass of water column across the continental slope

upper ocean currents around taiwan abstract current velocity measured by shipboard acoustic doppler current profiler sb adcp during 1991 2000 was used to study the upper ocean the composite and moored currents revealed a branch of the kuroshio that intruded steadily and persistently into the south china sea part of the intruded kuroshio flowed out of the south china sea through the northern luzon strait and re united with the main stream kuroshio the kuroshio had two velocity maximum cores southeast of taiwan but gradually combined into one as the kuroshio flowed north the kuroshio was deflected by the i lan ridge east of taiwan and the zonal running shelf break northeast of taiwan at the shelf break the kuroshio split with one branch intruding onto the shelf west of the luzon strait the kuroshio intruded into the south china sea some water flowed northward into the taiwan strait and re joined the kuroshio currents in the taiwan strait flowed primarily in a northward direction except for the southward current near the coast of mainland china north of the taiwan strait a branch of the northward flow followed the northern coast of taiwan to join the kuroshio the composite current varied consistently from season to season there was generally poor correlation between currents and local winds especially in the deep water regime remote forces were important in the currents around taiwan

the chemical composition of martian soil and rocks returned by the mobile alpha proton x ray spectrometer preliminary results from the x ray mode the alpha proton x ray spectrometer apxs on board the rover of the mars pathfinder mission measured the chemical composition of six soils and five rocks at the ares vallis landing site the soil analyses show similarity to those determined by the viking missions the analyzed rocks were partially covered by dust but otherwise compositionally similar to each other they are unexpectedly high in silica and potassium but low in magnesium compared to martian soils and martian meteorites the analyzed rocks are similar in composition to terrestrial andesites and close to the mean composition of earth s crust addition of a mafic component and reaction products of volcanic gases to the local rock material is necessary to explain the soil composition

transitional morphology in west deuteronilus mensae mars implications for modification of the lowland upland boundary abstract west deuteronilus mensae which lies along the lowland upland boundary of mars at 45 latitude 345 longitude exhibits both gradational l a rossbacher 1985 in models in geomorphology woldenberg ed pp 343 372 allen unwin boston and fretted terrain r p sharp 1973 j geophys res 78 4073 4083 boundary types to the west the boundary is gradational and to the east it is defined by fretted terrain the two types of boundaries do not merge with one another within the west deuteronilus mensae region however the gradational boundary materials appear to overlap the fretted terrain by about 500 km contacts between units associated with the gradational boundary and the fretted terrain boundary can both be recognized in the region of overlap the fretted terrain can be identified as much as 300 km north of the gradational boundary in this region lowland units associated with the gradational boundary embay canyons of the fretted terrain in a topographically conformal fashion changes in the fretted terrain across the gradational boundary from uplands to lowlands include a reduction of canyon wall slopes and depths such that the fretted terrain north of the gradational boundary appears mantled but not obscured there are at least two major classes of processes which might explain the lateral overlap 1 erosion of stratified upland terrain and 2 deposition of plains materials onto the sloping upland margin and fretted terrain erosion of stratified upland terrain does not adequately explain the plainward decrease in crater densities across the gradational boundary nor is it consistent with evidence that lowland plains material appears to onlap the sloping upland margin in several places of the possible plains emplacement mechanisms eolian deposition would not produce the sharp apparently topographically conformal gradational unit contacts volcanics plains emplacement would not preserve the complex geometry of the underlying fretted terrain sediment deposition in either a liquid or ice covered sea could produce the draped appearance of the fretted terrain outflow channels along the lowland upland boundary particularly those of the circum chryse and west elysium regions may have flooded the northern lowlands to depths of tens to hundreds of meters the gradational unit contacts may represent the shorelines of such a sea the scale of characteristic morphologies along these contacts may require an unfrozen condition of sufficient duration to allow lacustrine style wave erosion and redistribution of material along the contacts our limited understanding of the martian paleoclimate and h 2 o inventories allows the possibility of clement periods in the past and other geological evidence e g small valley networks and outflow channels strongly suggests an extensive role of liquid water

diagenetic sources of stable remanence in remagnetized paleozoic cratonic carbonates a rock magnetic study hysteresis measurements lowrie fuller tests cisowski tests and low temperature demagnetization experiments on samples of the knox dolomite trenton limestone and onondaga limestone indicate that the remanence in these remagnetized carbonate units resides principally in single domain magnetite in contrast to previous interpretations volumetrically however a significant fraction of the magnetite is coarser grained as previous scanning electron microscopic work on magnetic extracts has shown these conclusions are based mainly on the characteristic wasp waisted shape of the hysteresis loops and on the anomalously high ratios of remanent coercivity to bulk coercivity both of which clearly indicate a bimodal distribution of coercivities grain sizes the magnetization is controlled mainly by cubic magnetocrystalline anisotropy consistent with the spheroidal particles commonly observed in extracts hysteresis trends show that especially the finest particles lack shape anisotropy in view of these conclusions the two components of natural remanence in these rocks are interpreted as 1 a late paleozoic kiaman chemical remanence carried by single domain diagenetic magnetite and 2 a cenozoic thermoviscous overprint residing principally in coarser pseudosingle domain and multidomain magnetite also of late paleozoic diagenetic origin

spectral evidence for weathered basalt as an alternative to andesite in the northern lowlands of mars mineral abundances derived from the analysis of remotely sensed thermal emission data from mars have been interpreted to indicate that the surface is composed of basalt surface type 1 and andesite surface type 2 1 the global distribution of these rock types is divided roughly along the planetary dichotomy which separates ancient heavily cratered crust in the southern hemisphere basalt from younger lowland plains in the north andesite 1 but the existence of such a large volume of andesite is difficult to reconcile with our present understanding of the geological evolution of mars here we reinterpret martian surface rock lithologies using mineral abundances from previous work1 and new mineralogies derived from a spectral end member set representing minerals common in unaltered and low temperature aqueously altered basalts our results continue to indicate the dominance of unaltered basalt in the southern highlands but reveal that the northern lowlands can be interpreted as weathered basalt as an alternative to andesite the coincidence between locations of such altered basalt and a suggested northern ocean basin implies that lowland plains material may be composed of basalts weathered under submarine conditions or weathered basaltic sediments transported into this depocentre

searching for the source regions of martian meteorites using mgs tes integrating martian meteorites into the global distribution of igneous materials on mars the objective of this study was to identify and map possible source regions for all 5 known martian meteorite lithologies basalt lherzolite clinopyroxenite orthopyroxenite and dunite using data from the mars global surveyor thermal emission spectrometer mgs tes we deconvolved the tes data set using laboratory spectra of 6 martian meteorites los angeles zagami alh a77005 nakhla alh 84001 and chassigny as end members along with atmospheric and surface spectra previously derived from tes data global maps 16 pixels degree of the distribution of each meteorite end member show that meteorite like compositions are not present at or above tes detectability limits over most of the planet s dust free regions however we have confidently identified local scale 100s1000s km2 concentrations of olivine and orthopyroxene bearing materials similar to alh a77005 chassigny and alh 84001 in nili fossae in and near ganges chasma in the argyre and hellas basin rims and in eos chasma nakhla like materials are identified near the detection limit throughout the eastern valles marineris region and portions of syrtis major basaltic shergottites were not detected in any spatially coherent areas at the scale of this study martian meteorite like lithologies represent only a minor portion of the dust free surface and thus are not representative of the bulk composition of the ancient crust meteorite like spectral signatures identified above tes detectability limits in more spatially restricted areas tens of km are targets of ongoing analysis

the pattern and variability of winter kuroshio intrusion northeast of taiwan the variations of the kuroshio path and velocity northeast of taiwan are analyzed based on along track satellite altimeter data as well as high resolution model experiments observations reveal that in winter the kuroshio intrusion into the east china sea ecs at this location is manifested by a secondary maximum current core smcc shoreward of the kuroshio s main path the smcc varies significantly on interannual time scale and its variability is strikingly out of phase with that of the kuroshio entering the ecs meaning that the stronger the kuroshio the weaker the smcc and vice versa model experiments corroborate the observational results and more importantly indicate that the kuroshio intrusion here follows two primary routes a large anticyclonic loop that separates from the kuroshio at the northern end of taiwan and moves forward to form the smcc and a straight northward path onto the shelf when the kuroshio turns sharply eastward along the continental slope of the ecs the intrusion is controlled by both local forcing and remote effect with its pattern and variability depending mostly on the local heat flux and the inertia of the kuroshio current

geology of the mer 2003 elysium candidate landing site in southeastern utopia planitia mars 1 the nasa mars exploration rover mer project has been considering a landing site ellipse designated ep78b2 in southeastern utopia planitia southwest of elysium mons the site appears to be relatively safe for a mer landing site because of its predicted low wind velocities in mesoscale atmospheric circulation models and its low surface roughness at various scales as indicated by topographic and imaging data sets previously the site s surface rocks have been interpreted to be marine sediments or lava flows in addition we suggest that late noachian to early hesperian collapse and mass wasting of noachian highland rocks contributed to the deposition of detritus in the area of the ellipse furthermore we document partial late hesperian to early amazonian resurfacing of the ellipse by flows and vents that may be of mud or silicate volcanic origin a rover investigation of the utopia landing site using the mer athena instrument package might address some fundamental aspects of martian geologic evolution such as climate change hydrologic evolution and magmatic and tectonic history

surface textures and dynamics of the 2005 lava dome at shiveluch volcano kamchatka shiveluch is one of the largest and most active andesitic volcanoes of the kuril kamchatka arc it commonly alternates between vulcanian explosive eruptions and periods of dome growth and subsequent dome collapse driven block and ash flows the volcano was in an extended period of heightened activity for most of the period 2004 2010 we examined this activity in detail using thermal infrared tir remote sensing as part of the urgent request protocol urp program of the advanced spaceborne thermal emission and reflection radiometer aster instrument and confirmed the results with ground based photography and airborne tir camera data high spatial resolution tir images were collected during both daytime and nighttime satellite overpasses prior to and following the large explosive event eruption of 27 february 2005 and the dome growth that followed during a field campaign in august 2005 a helicopter overflight designed to acquire visible and tir data of the active dome was performed this was a nadir looking low altitude overflight and the first ever of shiveluch volcano involving non russian scientists the image data revealed an active crease structure in the center of the dome with a distinctly different crescent shaped high temperature 380 c zone roughly perpendicular to the crease in order to provide a time context and estimate extrusion rates the airborne data were compared to the spaceborne aster data and long distance ground based photography of the dome acquired by our russian colleagues the presence of a crease structure and the complex thermal pattern on the surface were both unexpected discoveries that reveal the way in which exogenous dome growth was occurring at the time this highly active period at shiveluch provides a unique example to better understand silicic lava dome growth using tir data the results also demonstrate a straightforward approach for fusing ground air and spaceborne image data which could be applied to other active domes around the world

differences between magnetic domain imaging observations and theory a quasi two dimensional model is developed to calculate domain structures in magnetite grains containing two to 20 domains the calculation shows that domains do not consist of uniformly magnetized regions consistent with the conclusions previously carried out on sub micron grains but that they become more uniformly magnetized for grains containing several domains consistent with domain imaging results in spite of improvement over previous calculations there remains a significant difference between the number of domains observed and calculated

generation and propagation of m 2 internal tides modulated by the kuroshio northeast of taiwan the variability and energetics of m 2 internal tides during their generation and propagation through the kuroshio flows northeast of taiwan are investigated using a high resolution numerical model the corrugated continental slopes particularly the i lan ridge and mien hua canyon are first identified as the energetic sources of m 2 internal tides the domain integrated m 2 barotropic to baroclinic conversion rate under the kuroshio influence is similar to 2 35gw similar to 0 9gw of which is generated at the i lan ridge similar to 0 93gw at the mien hua canyon and similar to 0 52gw at the north shelf the m 2 internal tide generation is influenced by the horizontally varying zonally tilting stratification associated with the kuroshio in this situation the conversion rate decreases by similar to 30 at the i lan ridge but increases to within similar to 10 at the mien hua canyon and north shelf in comparison to the simulation initiated with horizontal homogeneous stratification internal tides from multiple sources interfere to form a three dimensional baroclinic field the interference by the internal tides from the mien hua canyon and north shelf is refracted by the kuroshio and exhibits a mesoscale gyre pattern which can explain the frequent occurrence of internal solitary waves an energetic along slope tidal beam tbkc from the i lan ridge radiates southward against the northward kuroshio flows causing strong vertical displacement which favorably compares with recently reported field measurements the m 2 internal tide energy dissipates primarily near the source sites and the remaining energy radiates outward over limited distances complex topographic features and background currents enhance the internal tide dissipation which induces strong inhomogeneous diapycnal mixing

the sedimentology and dynamics of crater affiliated wind streaks in western arabia terra mars and patagonia argentina abstract wind streaks comprise recent aeolian deposits that have been extensively documented on venus earth and mars martian wind streaks are among the most abundant surface features on the planet and commonly extend from the downwind margins of impact craters previous studies of wind streaks emerging from crater interior deposits suggested that the mode of emplacement was primarily related to the deposition of silt sized particles as these settled from plumes we have performed geologic investigations of two wind streaks clusters one situated in western arabia terra a region in the northern hemisphere of mars and another in an analogous terrestrial site located in southern patagonia argentina where occurrences of wind streaks emanate from playas within maar craters in both these regions we have identified bedforms in sedimentary deposits on crater floors along wind facing interior crater margins and along wind streaks these observations indicate that these deposits contain sand sized particles and that sediment migration has occurred via saltation from crater interior deposits to wind streaks in arabia terra and in patagonia wind streaks initiate from crater floors that contain lithic and evaporitic sedimentary deposits suggesting that the composition of wind streak source materials has played an important role in development spatial and topographic analyses suggest that regional clustering of wind streaks in the studied regions directly correlates to the areal density of craters with interior deposits the degree of proximity of these deposits and the craters rim to floor depths in addition some but not all wind streaks within the studied clusters have propagated at comparable yearly earth years rates extensive saltation is inferred to have been involved in its propagation based on the studied terrestrial wind streak that shows ripples and dunes on its surface and the martian counterpart changes orientation toward the downslope direction where it extends into an impact crater

eddy kuroshio interaction processes revealed by mooring observations off taiwan and luzon the influence and fate of westward propagating eddies that impinge on the kuroshio were observed with pressure sensor equipped inverted echo sounders piess deployed east of taiwan and northeast of luzon zero lag correlations between pies measured acoustic travel times and satellite measured sea surface height anomalies ssha which are normally negative have lower magnitude toward the west suggesting the eddy influence is weakened across the kuroshio the observational data reveal that impinging eddies lead to seesaw like ssha and pycnocline depth changes across the kuroshio east of taiwan whereas analogous responses are not found in the kuroshio northeast of luzon anticyclones intensify sea surface and pycnocline slopes across the kuroshio while cyclones weaken these slopes particularly east of taiwan during the 6 month period of overlap between the two pies arrays only one anticyclone affected the pycnocline depth first at the array northeast of luzon and 21 days later in the downstream kuroshio east of taiwan

interannual variability of the kuroshio onshore intrusion along the east china sea shelf break effect of the kuroshio volume transport the interannual variability of the kuroshio onshore intrusion koi across the east china sea ecs shelf break and its response to the ecs kuroshio volume transport kvt during 1993 approximate to 2010 are studied based on a high resolution real time and global ocean general circulation model since variability of kvt is mainly determined in the interior pacific it is rather a remote than a local factor for the local ecs koi on interannual time scales kvt affects koi not only in the net volume transport across the entire shelf break but also in the spatial pattern along the shelf break when kvt increases the intrusion decreases increases upstream downstream of the major intrusion region northeast of taiwan the retreating increases decreases upstream downstream of the main veering region southwest of kyushu these patterns are caused by cyclonic eddies induced by the seaward deflection of the kuroshio axis from the shelf break which ultimately results from the kvt increase a diagnostic mechanism of koi approximate to msin delta h 1 is proposed where h is the bottom depth is the angle between isobaths and the vertically averaged current and m is the absolute volume transport at the shelf break is large in the major intrusion retreating regions and stable on interannual time scales while m changes with opposite signs between upstream and downstream of the major intrusion retreating regions the mechanism explains well the relation of local kvt and the spatial pattern of koi along the shelf break in both the mean state and the interannual variations

impact melts and glasses on mars 1 dark mobile materials on mars are widely considered to be volcanically derived windblown particulates such a conclusion is consistent with the large volcanic edifices on mars and the assumption that a volatile rich crust would not favor significant impact melt generation several post viking discoveries however provide new perspectives for reconsidering alternative origins not only for some of the mobile dark veneers but also certain materials at the pathfinder and viking landing sites first certain dark materials on mars do not exhibit the expected mafic absorption features in their reflectance spectra second the pathfinder mission revealed unexpected feldspathic compositions of vesicular blocks that lead to a preliminary conclusion that they represent andesites or basaltic andesites rather than basalts third recent discoveries of holocene to miocene impacts in argentine loessoid deposits provide new insights for the nature of melts generated from eolian sediments fourth global dispersal of impact melt products are now recognized in the terrestrial record throughout the cenozoic consequently the generation and preservation of impact glass on mars should be reconsidered possible occurrences include possible tektite like strewnfields downrange from recent oblique impacts dark avalanches emerging from backwasting cliffs of easily eroded unconformable deposits global dispersal of glassy ejecta from hesperian and amazonian craters of chicxulub scale and dark mobile veneers emerging from noachian craters we propose that the mobile dark materials comprising many of the named features of mars as well as some blocks at the pathfinder viking landing sites may represent impact melt products

an estimate of the cross frontal transport at the shelf break of the east china sea with the finite volume coastal ocean model 1 the finite volume coastal ocean model fvcom is used to estimate the onshore cross frontal transport at the shelf break of the east china sea boundary conditions of fvcom are provided by the princeton ocean model simulating ocean currents in the yellow sea and east china sea realistically one advantage of this study is that the unstructured triangular cell grid of fvcom resolves complex bottom topography that may trigger kuroshio frontal waves it is anticipated that these nonlinear frontal waves enhance the exchange of seawater between the kuroshio and shelf regions kuroshio frontal waves in the model are excited around the location where the bottom slope changes abruptly and have the phase speed and amplitude consistent with those observed in the east china sea in addition the model reproduces the onshore transport associated with growing frontal waves in the upper and lower layers on the basis of passive tracer experiments the annually averaged onshore transport integrated along the shelf break is estimated to be 0 85 106 m3 s

possible ancient oceans on mars evidence from mars orbiter laser altimeter data high resolution altimetric data define the detailed topography of the northern lowlands of mars and a range of data is consistent with the hypothesis that a lowland encircling geologic contact represents the ancient shoreline of a large standing body of water present in middle mars history the contact altitude is close to an equipotential line the topography is smoother at all scales below the contact than above it the volume enclosed by this contact is within the range of estimates of available water on mars and a series of extensive terraces parallel the contact in many places

interannual variations of kuroshio transport in the east china sea and its relation to the pacific decadal oscillation and mesoscale eddies results of a data assimilative ocean model jcope2 from 1993 to 2012 were used to examine the correlation between the pacific decadal oscillation pdo index and interannual variations of the kuroshio transport in the east china sea ecs and the influences of mesoscale eddies on this correlation in a period from 1993 to 2002 the kuroshio transport estimated from the jcope2 reanalysis has a positive correlation with the pdo index this well known correlation became weak or even disappeared when the analysis period was extended from 1993 2002 to 1993 2012 this occurs because the variation range of the pdo index became small during enhanced mesoscale eddy activity southeast of taiwan in years after 2002 the eddies caused a larger variation in the kuroshio transport in the years after 2002 than before 2002 and therefore changed the correlation between the pdo index and kuroshio transport in the ecs the influence of mesoscale eddies on the kuroshio transport has strong regional dependence the kuroshio transport from the area east of taiwan to the midway along the shelf break in the east china sea depends mainly on eddies arriving from southeast of taiwan while transport from the midway along the shelf break to the tokara strait depends mainly on the eddies arriving from northeast of okinawa island the combination of pdo related signals and eddy related signals determines the interannual variations of the kuroshio transport in the ecs and sufficient attention must be paid to the spatial dependence of the kuroshio transport in the ecs on eddies

seasonal and interannual changes of the kuroshio intrusion onto the east china sea shelf an advanced artificial neural network classification algorithm is applied to 20 years of multisatellite geostrophic velocity data to study the kuroshio intrusion onto the southern shelf of the east china sea the results suggest that the on shelf intrusion may occur year round but winter intrusion events are more frequent than summer events both stronger intrusion which is closely correlated to surface heat flux gradient and weaker intrusion which is correlated to wind forcing occur during wintertime but the former dominates in late winter while the latter prevails in early winter there is a significant year to year variation of the winter on shelf intrusion although on shelf intrusion is the major characteristic of the region during wintertime seldom intrusion events have been identified in the winters of 1997 1998 and 2002 2003 two conditions are responsible for the cause of the nonintrusion events during the two nonintrusion winters the upstream kuroshio transport anomaly is insignificant the kuroshio is not weakened and no significant winter cooling off northeast taiwan thus the kuroshio tends to flow along the shelf break following the 200 m isobath and on shelf intrusion ceases those two nonintrusion events take place during the winters when both the nino 3 4 index and the pdo index are large and positive

fluctuations of the thermal fronts off northeastern taiwan 1 a high resolution sea surface temperature sst data derived from several satellites is used to investigate the variability of the thermal front off northeastern taiwan hidden by a dominant annual cycle the sst data cannot reveal the thermal front fluctuation in the form of hovmoller diagram an innovative methodology has been applied to the sst satellite imagery to derive the sst standardized index sstsi capable of revealing the frontal variability with multiple time scales principal component analysis shows that the sstsi variation consists mainly of two modes mode 1 represents a strong annual cycle related to the seasonal reversal of the monsoonal winds the temperature gradient is enhanced in winter and a cold dome is observed off northern taiwan in summer mode 2 is highly correlated with the upstream kuroshio variability the shoreward seaward migration of the thermal front takes place when the kuroshio transport weakens strengthens the results are consistent with transports estimated by tidal gauge measurements satellite altimeter based sea level anomaly and surface flow patterns derived from high frequency radars mode 2 is coherent with the kuroshio transport through the east taiwan channel at periods of 120 and 45 d with a time lag of 40 and 11 d respectively this 120 d fluctuation is due to the interaction between westward propagating eddies and the kuroshio east of taiwan while the 45 d signal arises from the kuroshio s self instability the interannual variations of the sst pattern in winter and summer are also discussed

quantitative compositional analysis of martian mafic regions using the mex omega reflectance data 1 methodology uncertainties and examples of application abstract the mars express observatoire pour la mineralogie l eau les glaces et l activite omega collected an unprecedented visible and near infrared hyperspectral dataset covering the low albedo regions of mars we investigate the ability to infer modal abundance of surfaces of these regions from a radiative transfer model developed by shkuratov et al shkuratov y starukhina l hoffmann h arnold g 1999 icarus 137 235 246 and adapted to basaltic surfaces by poulet and erard poulet f erard s 2004 j geophys res 109 e2 doi 10 1029 2003je002179 from omega measurements of mafic surfaces we develop several sensitivity tests to assess the extent to which the model can be applied to predict pyroxene composition high calcium phase and low calcium phase abundance of almost neutral components plagioclase in the near infrared wavelength as well as grain sizes by using a library of selected end members results of the sensitivity tests indicate that the scattering model can estimate both abundances and grain sizes of major basaltic materials of low albedo regions within uncertainties 5 to 15 vol the model is then applied to data from dissected cratered terrains located in terra meridiani the derived grain size including uncertainties is in the 50 500 m range this is consistent with the thermal inertia and albedo of this region which indicates a fine sand sized surface with little dust the abundances of plagioclase 43 57 and pyroxenes 35 45 10 including 11 5 of low calcium phase are in good agreement with previous basalt like compositions of low albedo regions from thermal infrared spectral measurements the method presented in this paper will provide a valuable tool for evaluating the modal mineralogy of other mafic regions of mars observed in the near infrared wavelength range

numerical study on the pattern and origins of kuroshio branches in the bottom water of southern east china sea in summer pattern and origins of kuroshio branches in the bottom water of southern east china sea ecs were carefully examined by numerical simulations based on the regional ocean modeling system roms together with observations model results show that in the bottom water of ecs the intrusion pattern of kuroshio is mainly composed of an offshore kuroshio branch current okbc which bifurcated from the kuroshio northeast of taiwan flows nearly along the isobath of similar to 100 m and a nearshore kuroshio branch current nkbc which originated from the kuroshio northeast of taiwan upwells northwestward gradually from similar to 250 m to similar to 60 m then turns to northeast around 27 5 degrees n 122 e thereafter flows northeastward along the isobath of similar to 60 m and finally reaches at 30 5 degrees n where it turns to east furthermore we found that the nkbc mostly originated in the kuroshio subsurface water 120 250 m east of taiwan whereas the okbc mainly stemmed from the kuroshio water 60 120 m east of taiwan this pattern and origins of okbc and nkbc well addressed the observational phenomena that off the coast of zhejiang province china there were colder less saline and more phosphate rich bottom water near the isobath of similar to 60 m rather than near the isobath of similar to 100 m in august 2009 finally it is proposed that on southern ecs continental shelf kuroshio exhibits its intrusion branches by an anticyclonical stair structure bottom stair nkbc middle stair okbc and top stair kuroshio surface branch kbc

impacts of the mid latitude westerlies anomaly on the decadal sea level variability east of china the present analysis has revealed that both the altimetry and tide gauge records show a prominent sea level rise from 1993 to 2016 in the coastal seas east of china including bohai yellow sea and east china sea byecs the regional mean sea level rise rate for the byecs continental shelf area is 3 2 mm year which is close to the global mean 2 9 mm year besides the rising trend the byecs sea level anomaly sla also shows obvious interannual and decadal oscillation it is found that the mid latitude westerlies rather than the steric height variability are responsible for these oscillations by analyzing the 67 year 1950 2016 hindcast outputs from an eddy resolving ocean general circulation model a 14 2 years decadal period is found to dominate the byecs sla variability and the decadal oscillation is positively correlated with the north pacific gyre oscillation npgo the composite analysis and causality analysis demonstrate that during the positive phase of the npgo the mid latitude westerlies decrease and a positive wind stress curl anomaly at the same latitude of the east china sea s kuroshio occurs to the south of the westerlies consequently the kuroshio current volume transport and sea surface height difference between the two sides of the kuroshio decrease that is the sea level in the byecs rises

stratified ekman layers under fair weather conditions the time averaged wind driven current forms a spiral in which the current vector decays and turns clockwise with increasing depth these spirals resemble classical ekman spirals they differ in that their rotation depth scale exceeds the e folding depth of the speed by a factor of 2 to 4 and they are compressed in the downwind direction a related property is that the time averaged stress is evidently not parallel to the time averaged vertical shear we develop the hypothesis that the flat spiral structure may be a consequence of the temporal variability of stratification within the upper 10 20 m of the water column this variability is associated primarily with the diurnal cycle and can be treated by a time dependent diffusion model or a mixed layer model the latter can be simplified to yield a closed solution that gives an explicit account of stratified spirals and reasonable hindcasts of midlatitude cases at middle and higher latitudes the wind driven transport is found to be trapped mainly within the upper part of the ekman layer the diurnal warm layer at tropical latitudes the effects of diurnal cycling are in some ways less important and ekman layer currents are likely to be significant to much greater depths in that event the lower part of the ekman layer is likely to be affected by stratification variability that may be nonlocal

theoretical and experimental studies of magnetic domains the primary purpose of this paper is to review recent contributions from north american scientists to theory and observations of magnetic domain structures in magnetic minerals common to rocks although rock magnetism deals with all the magnetic properties of rocks a major goal of rock magnetists has been to understand the origins and properties of remanent magnetization rm a remanent magnetization is defined as the magnetization that exists in the absence of an external magnetic field the analyses of rms of which there are more than 20 kinds have led to the numerous and well known successes of paleomagnetism

the rocks of gusev crater as viewed by the mini tes instrument 1 the miniature thermal emission spectrometer mini tes on board the mars exploration rover spirit is part of a payload designed to investigate whether a lake once existed in gusev crater mini tes has observed hundreds of rocks along the rover s traverse into the columbia hills yielding information on their distribution bulk mineralogy and the potential role of water at the site although dust in various forms produces contributions to the spectra we have established techniques for dealing with it all of the rocks encountered on the plains traverse from the lander to the base of the columbia hills share common spectral features consistent with an olivine rich basaltic rock known as adirondack class beginning at the base of the west spur of the columbia hills and across its length the rocks are spectrally distinct from the plains but can be grouped into a common type called clovis class these rocks some of which appear as in place outcrop are dominated by a component whose spectral character is consistent with unaltered basaltic glass despite evidence from other rover instruments for significant alteration the northwest flank of husband hill is covered in float rocks known as wishstone class with spectral features that can be attributed uniquely to plagioclase feldspar a phase that represents more than half of the bulk mineralogy rare exceptions are three classes of basaltic exotics found scattered across husband hill that may represent impact ejecta and or float derived from local intrusions within the hills the rare outcrops observed on husband hill display distinctive spectral characteristics the outcrop called peace shows a feature attributable to molecular bound water and the outcrop that hosts the rock called watchtower displays a dominant basaltic glass component despite evidence from the rover s payload for significant alteration of some of the rocks no unambiguous detection of crystalline phyllosilicates or other secondary silicates has been observed by mini tes the mineralogical results supplied by mini tes provide no clear evidence that a lake once existed in gusev crater

in situ compositions of martian volcanics implications for the mantle the primary objective of this analysis is to determine the mineralogic composition of relatively pristine terrains exposed on the surface of mars this analysis is conducted using imaging spectrometer data acquired in 1989 by the imaging spectrometer for mars ism instrument that was onboard the phobos ii spacecraft the ism instrument acquired some of the highest spectral 64 channels between 0 77 and 3 14 m and spatial resolution 22 km pixel observations to date of mars focused on the equatorial region relatively unaltered surfaces were identified in these data on the basis of their spectral properties low albedo weak spectral slope absence of ferric absorptions and were found in volcanic terrains of syrtis major valles marineris ophir planum and sinus meridiani oxia palus spectra representative of the diversity among terrains were extracted for detailed analysis using the modified gaussian model to determine the primary mafic mineralogy it was determined that the mafic mineralogy of the regions investigated is dominated by low calcium and high calcium pyroxene lcp hcp and that there was homogeneity within a given region but some heterogeneity between regions in the relative abundance of lcp to hcp the two pyroxene mineralogy is consistent with the mineralogies of the basaltic snc meteorites believed to have originated on mars two pyroxene volcanic mineralogies are indicative of large degrees of partial melting e g komatiites or a mantle source depleted in aluminum integration of these findings with previous studies of mars and the snc meteorites indicates that 1 the snc mineralogies are representative of large volcanic regions of mars with surface ages as old as 2 3 ga 2 the martian mantle was depleted in aluminum at least as long ago as the oldest terrain analyzed ophir planum and 3 there has been little evolution in the composition of mantle source regions as the 180 ma snc mineralogies are comparable to those of the oldest terrains analyzed

magmatic cristobalite and quartz in the nwa 856 martian meteorite silica rich late stage crystallization pockets in the martian meteorite northwest africa nwa 856 were investigated by transmission electron microscopy tem the pockets occur as wedges between maskelynite laths or between maskelynite and pyroxene they consist of elongated grains of cristobalite and quartz embedded in a silica rich glass interstitial to the amorphous phase and silica minerals a number of small accessory minerals have been identified typical for late stage crystallization products they are ilmenite tranquillityite fayalite troilite baddeleyite apatite and chloroapatite cristobalite and quartz are shocked as revealed by the occurrence of numerous amorphous lamellae this assemblage suggests metastable dendritic crystallization under hydrous conditions cristobalite crystallization was probably facilitated by the presence of impurities such as na or h2o our observations show that silica minerals can be formed under magmatic conditions on mars

mineralogy of martian atmospheric dust inferred from thermal infrared spectra of aerosols 1 we have utilized optical constants derived from thermal infrared spectra acquired by the mariner 9 infrared interferometer spectrometer m9 iris and mars global surveyor thermal emission spectrometer mgs tes during periods of relatively high dust low water ice opacity to generate synthetic transmission and emission spectra of the atmospheric dust using libraries of transmission and emission spectra of common rock forming minerals and their alteration products we applied a linear deconvolution algorithm to the spectra to model the dust mineralogy models of the m9 iris transmission data generally are of poor quality and the mineralogical results of these fits are unlikely to be valid fits to the tes transmission spectrum and tes and iris emission spectra are of better quality and suggest that the dust mineralogy is dominated by framework silicates feldspar and or zeolite with carbonate sulfate pyroxene and olivine identified near but below generalized detection limits evidence for phyllosilicates is not robust our results combined with those from in situ measurements and other visible to infrared spectral studies suggest that framework silicates probably feldspar dominate the dust mineralogy with lesser amounts of olivine pyroxene amorphous material hematite and magnetite and that the dust largely is the product of mechanical weathering of basaltic rocks with minor chemical alteration

analysis of terrestrial and martian volcanic compositions using thermal emission spectroscopy 2 application to martian surface spectra from the mars global surveyor thermal emission spectrometer atmospherically corrected thermal infrared spectra of large regions of the martian surface from the mars global surveyor thermal emission spectrometer mgs tes previously have been interpreted to represent two general spectral classes one class represents a basalt to basaltic andesite composition and the other class represents a basaltic andesite to andesite composition we have performed new linear deconvolutions of the two martian surface type spectra with an end member set tailored to represent volcanic rock types our preparatory study of laboratory spectra of terrestrial volcanic rocks acquired at 2 cm 21 sampling convolved to tes spectral sampling 10 cm 21 shows little degradation in deconvolution results when compared to results acquired using the higher spectral resolution data indicating that the deconvolution technique is valid for analyzing data at tes resolution our spectral fits to the martian data agree well with previous models and do not exhibit any notable deviations from the martian spectra that would indicate the absence of any significant end members in our model modal mineralogies obtained with these new spectral fits also compare favorably within the previously stated uncertainties to prior results the newly derived modal mineralogies are used with new and traditional classification schemes for volcanic igneous rocks introduced in a companion paper wyatt et al this issue to classify the martian compositions our results substantiate the previously proposed hypothesis that these two spectral classes on the martian surface represent volcanic compositions with distinguishable differences in silica content ranging from basalt to andesite

remagnetization of the tonoloway formation and the helderberg group in the central appalachians testing the origin of syntilting magnetizations summary palaeomagnetic rock magnetic geochemical and strain studies of the helderberg group and the tonoloway formation in the valley and ridge province of west virginia were performed to test the origin of syntilting magnetizations and to test the mechanisms of chemical remanent magnetization crm acquisition the test for a connection between strain and remagnetization was performed by comparing the types and levels of strain with the magnetic properties between the generally coarse grained thickly bedded helderberg and the thinly bedded and finer grained tonoloway standard tilt tests as well as optimal differential untilting from two transects on the wills mountain anticline indicate that the helderberg contains a pervasive late syntilting 30 per cent untilting characteristic remanent magnetization chrm whereas the tonoloway contains a well defined early syntilting chrm 1 76 per cent untilting as well as a chrm 2 which is similar to the chrm in the helderberg the chrms reside in magnetite the rock magnetic results from the two units are similar although the helderberg samples have a finer apparent grain size perhaps as a result of magnetic hardening strain data reveal an apparent correlation between the syntilting magnetizations and types degrees of pressure solution strain pressure solution strain is higher in the helderberg and lower in the tonoloway strain may have caused rotation of magnetic minerals but it not clear that the differences in strain between the units were high enough to cause the rotations that are needed to explain the tilt test results several other viable hypotheses were also investigated one hypothesis is a strain enhanced chemical process that caused dissolution and precipitation of new magnetite in solution structures during folding a preliminary test of this hypothesis produced inconclusive results another hypothesis consistent with some of the characteristics of the magnetizations in the helderberg and tonoloway units is that the rocks were partially to completely remagnetized by a piezoremanent remagnetization process geochemical results show that origin of the remanence carrying grains cannot be attributed to orogenic type fluids but were probably caused by a burial diagenetic process

geochemical evidence for magmatic water within mars from pyroxenes in the shergotty meteorite observations of martian surface morphology have been used to argue that an ancient ocean once existed on mars1 it has been thought that significant quantities of such water could have been supplied to the martian surface through volcanic outgassing but this suggestion is contradicted by the low magmatic water content that is generally inferred from chemical analyses of igneous martian meteorites2 here however we report the distributions of trace elements within pyroxenes of the shergotty meteorite a basalt body ejected 175 million years ago from mars3 as well as hydrous and anhydrous crystallization experiments that together imply that water contents of pre eruptive magma on mars could have been up to 1 8 we found that in the shergotty meteorite the inner cores of pyroxene minerals which formed at depth in the martian crust are enriched in soluble trace elements when compared to the outer rims which crystallized on or near to the martian surface this implies that water was present in pyroxenes at depth but was largely lost as pyroxenes were carried to the surface during magma ascent we conclude that ascending magmas possibly delivered significant quantities of water to the martian surface in recent times reconciling geologic and petrologic constraints on the outgassing history of mars

mixing relationships in the martian regolith and the composition of globally homogeneous dust abstract comparison of the chemical compositions of martian soils reveals distinct mixing trends resulting from admixture of variable amounts of sulfate chloride cement at viking landing sites and of the local andesitic rock fragments at the mars pathfinder site these trends most easily visualized in plots of oxides versus so 3 intersect approximately at a common composition thought to represent a global dust that has been homogenized by pervasive aeolian activity the source rocks that were weathered to produce the global dust are inferred to have been basalts rather than felsic rocks based on the observation that the dust lies along well established chemical weathering trends for terrestrial basalts the basaltic protolith was chemically similar e g high fe mg low al 2 o 3 to basaltic shergottite meteorites chemical changes during the weathering of martian basaltic rocks are apparently not as drastic as in terrestrial weathering perhaps because of evaporation of hydrous fluids that leave soluble components behind in the residue comparison with chemical trends for previously proposed martian soil formation mechanisms suggests that palagonitization of basalts more readily explains the dust composition than do hydrothermal alteration at higher temperatures or reactions of rocks with an acid fog produced by volcanic exhalations local or temporal processing of dust into soil involves not only cementation by salts and mixing with rock fragments but also chemical fractionations of fe 2 o 3 tio 2 presumably resulting from aeolian sorting by grain size and density if the global dust represents a broad average of the martian surficial or upper crustal composition the planet s surface geology is dominated by basaltic volcanic rocks and evaporitic salts

interpretations of the jebar term abstract in diagnostic calculations of the ocean s circulation the so called jebar joint effect of baroclinicity and relief term may induce a significant depth average current field as has been noted in the oceanographic literature here we present two consistent interpretations of this term in the equation governing the vorticity of the depth averaged current a topographic vortex stretching term proportional to the dot product of depth averaged velocity and the depth gradient arises we show that jebar corrects this term by removing the contribution of the geostrophic flow referenced to the bottom which cannot generate topographic vortex stretching in the evolution equation for the vorticity of the depth integrated flow a bottom torque term is present we show that the jfbar term discussed above enters here as a contribution to the bottom torque emphasizing the role of jebar as a forcing term we also show that when a diagnostic calculation is formulated completely in terms of the transport str

young lava flows on the eastern flank of ascraeus mons rheological properties derived from high resolution stereo camera hrsc images and mars orbiter laser altimeter mola data 1 we report on estimates of the rheological properties of late stage lava flows on the eastern flank of ascraeus mons mars from previous studies it is known that the dimensions of flows reflect rheological properties such as yield strength effusion rates and viscosity our estimates are based on new high resolution images obtained by the high resolution stereo camera hrsc on board the european space agency s mars express spacecraft in combination with mars orbiter laser altimeter mola data compared to earlier studies the high spatial resolution of the hrsc and mola data allowed us to map 25 late stage lava flows and to measure their dimensions as well as their morphological characteristics in greater detail our estimates of the yield strengths for these flows range from 2 0 102 pa to 1 3 105 pa with an average of 2 1 104 pa these values are in good agreement with estimates for terrestrial basaltic lava flows and are comparable to previous estimates derived for a small number of lava flows on ascraeus mons our investigation indicates that the effusion rates for the studied ascraeus mons flows are on average 185 m3 s 1 ranging from 23 m3 s 1 to 404 m3 s 1 these results are higher than earlier findings that indicate effusion rates of 18 60 m3 s 1 with an average of 35 m3 s 1 however our effusion rates are similar to terrestrial effusion rates of kilauea and mauna loa and other martian volcanoes on the basis of our estimates of the effusion rates and the measured dimensions of the flows we calculated that the time necessary to emplace the flows is on average 26 days viscosities were estimated on the basis of yield strengths and effusion rates yielding average values of 4 1 106 pa s and ranging from 1 8 104 pa s to 4 2 107 pa s on the basis of newly available data sets e g hrsc mola we are now able not only to identify possible differences in eruptive behavior between ascraeus mons and elysium mons but also to study such differences over time

on kuroshio front fluctuations in the east china sea using satellite and in situ observational data fluctuations of the kuroshio front in the east china sea and their relation to variations of the kuroshio stream around the tokara strait are investigated using consecutive satellite images sea level data as well as water temperature records from a japan meteorological agency buoy station and a ferryboat which crosses the tokara strait meanders of the kuroshio front with typical horizontal scales of 100 to 150 km and wave periods of 14 to 20 days are found to appear ubiquitously in the east china sea the front meanders originate upstream over the continental slope and evolve rapidly while propagating downstream at speeds of 20 to 26 cm s 1 downstream southwest of kyushu the fully developed meanders sometimes take the form of warm filaments and when the volume transport of the kuroshio is large they may develop into shed off warm eddies previous observations based on ferryboat temperature records have revealed the repeated northward migration of a clear sea surface temperature sst front across the tokara strait it is shown that this northward migration of the sst front corresponds to the passage of the kuroshio front meanders across the tokara strait and that the unclear southward migration of the sst front is due to the presence of mixed water behind each meander the kuroshio front meanders in the east china sea are further found to be closely related to the north southward movement of the entire kuroshio stream in the tokara strait a lag of about 10 days exists between the time the front meanders reach the tokara strait and the kuroshio stream there shifts to its northernmost position

seasonal to interannual variations in the intensity and central position of the surface kuroshio east of taiwan 1 seasonal and interannual changes of surface kuroshio intensity and central position east of taiwan during 1993 2012 are investigated by quantitatively analyzing the satellite altimetry product the kuroshio moves inshore offshore off northeast of taiwan in winter summer whereas it has an offshore inshore path off southeast of taiwan in winter summer the seasonal change of heat flux over the east china sea shelf is found to cause the seasonality of the kuroshio central position off northeast of taiwan whereas the seasonal kuroshio movement off southeast of taiwan is found to be induced by the combined effect of the kuroshio changes through the luzon strait and the eastern luzon island in contrast to this y dependent path changes the kuroshio becomes weaker stronger as a whole east of taiwan in winter summer on the interannual time scales the kuroshio throughout the eastern coast of taiwan intensifies and has a concurrent offshore path during the periods of 1995 1997 and 2004 2007 the relative intensity of cyclonic eddies to anticyclonic eddies off eastern taiwan are found to contribute to these interannual kuroshio changes

chemical multispectral and textural constraints on the composition and origin of rocks at the mars pathfinder landing site rocks at the mars pathfinder site are probably locally derived textures on rock surfaces may indicate volcanic sedimentary or impact generated rocks but aeolian abration and dust coatings prevent unambiguous interpretation multispectral imaging has resolved four spectral classes of rocks gray and red which occur on different surfaces of the same rocks pink which is probably soil crusts and maroon which occurs as large boulders mostly in the far field rocks are assigned to two spectral trends based on the position of peak reflectance the primary spectral trend contains gray red and pink rocks maroon rocks constitute the secondary spectral trend the spatial pattern of spectral variations observed is oriented along the prevailing wind direction the primary spectral trend arises from thin ferric coatings of aeolian dust on darker rocks the secondary spectral trend is apparently due to coating by a different mineral probably maghemite or ferrihydrite a chronology based on rock spectra suggests that rounded maroon boulders constitute the oldest petrologic unit a flood deposit succeeded by smaller cobbles possibly deposited by impact and followed by aeolian erosion and deposition nearly linear chemical trends in alpha proton x ray spectrometer rock compositions are interpreted as mixing lines between rock and adhering dust a conclusion supported by a correlation between sulfur abundance and red blue spectral ratio extrapolations of regression lines to zero sulfur give the composition of a presumed igneous rock the chemistry and normative mineralogy of the sulfur free rock resemble common terrestrial volcanic rocks and its classification corresponds to andesite igneous rocks of this composition may occur with clastic sedimentary rocks or impact melts and breccias however the spectral mottling expected on conglomerates or breccias is not observed in any apxs analyzed rocks interpretation of the rocks as andesites is complicated by absence of a 1 m pyroxene absorption band plausible explanations include impact glass band masking by magnetite or presence of calcium and iron rich pyroxenes and olivine which push the absorption band minimum past the imager s spectral range the inferred andesitic composition is most similar to terrestrial anorogenic icelandites formed by fractionation of tholeiitic basaltic magmas early melting of a relatively primitive martian mantle could produce an appropriate parent magma supporting the ancient age of pathfinder rocks inferred from their incorporation in hesperian flood deposits although rocks of andesitic composition at the pathfinder site may represent samples of ancient martian crust inferences drawn about a necessary role for water or plate tectonics in their petrogenesis are probably unwarranted

evidence for magnetostrictive control of intrinsic susceptibility and coercive force of multidomain magnetite in rocks abstract it is shown that intrinsic susceptibility xi susceptibility in the absence of self demagnetizing fields as well as coercive force hc of multidomain magnetite in rocks are likely to be commonly magnetostrictively controlled presumably through internal stresses opposing domain wall motion we use observations of the thermal variation of observed susceptibility x per cm3 of magnetite in the sample and coercive force hc on cooling to 130 k for seven basaltic rocks and for 0 25 0 21 mm magnetite grains dispersed in cement as expected theoretically with magnetostrictively controlled xi a plot of 1 x versus j s 2 for each sample where is the polycrystalline magnetostriction coefficient and js is saturation magnetization gives a reasonably straight line whose 1 x intercept agrees with n average self demagnetizing factor of magnetite grains in the sample given by h c j r n h c j r h c j ri where jr is saturation remanence and ri is jr when n 0 as expected theoretically with magnetostrictively controlled hc a plot of hc versus j s for each sample reveals an approximate proportionality this also implies magnetostrictive control of xi because a plot of 1 x versus h c j s for each sample yields a straight line of 1 x intercept agreeing with n from h c j r n h c j r h c j ri as expected if hc and xi are both magnetorestrictively controlled

the kuroshio east of taiwan moored transport observations from the woce pcm 1 array observations from the woce pcm 1 moored current meter array east of taiwan for the period september 1994 to may 1996 are used to derive estimates of the kuroshio transport at the entrance to the east china sea three different methods of calculating the kuroshio transport are employed and compared these methods include 1 a direct method that uses conventional interpolation of the measured currents and extrapolation to the surface and bottom to estimate the current structure 2 a dynamic height method in which moored temperature measurements from moorings on opposite sides of the channel are used to estimate dynamic height differences across the current and spatially averaged baroclinic transport profiles and 3 an adjusted geostrophic method in which all moored temperature measurements within the array are used to estimate a relative geostrophic velocity field that is referenced and adjusted by the available direct current measurements the first two methods are largely independent and are shown to produce very similar transport results the latter two methods are particularly useful in situations where direct current measurements may have marginal resolution for accurate transport estimates these methods should be generally applicable in other settings and illustrate the benefits of including a dynamic height measuring capability as a backup for conventional direct transport calculations the mean transport of the kuroshio over the 20 month duration of the experiment ranges from 20 7 to 22 1 sv 1 sv 106 m3 s 1 for the three methods or within 1 3 sv of each other the overall mean transport for the kuroshio is estimated to be 21 5 sv with an uncertainty of 2 5 sv all methods show a similar range of variability of 10 sv with dominant timescales of several months fluctuations in the transport are shown to have a robust vertical structure with over 90 of the transport variance explained by a single vertical mode the moored transports are used to determine the relationship between kuroshio transport and sea level difference between taiwan and the southern ryukyu islands allowing for long term monitoring of the kuroshio inflow to the east china sea

impact of mesoscale eddies on kuroshio intrusion variability northeast of taiwan abundant mesoscale eddies propagate to the east of taiwan and affect the kuroshio current and its onshore intrusion northeast of taiwan but the dynamical process of how eddy activities modulate the kuroshio intrusion is still unclear in this study in situ ocean velocity observations drifter trajectories tide gauge measurements satellite sea surface height data and assimilative hybrid coordinate ocean model hycom reanalysis outputs were used to analyze a cyclonic eddy induced large kuroshio onshore intrusion during late autumn 2008 along with nine anticyclonic eddy events and seven cyclonic eddy events extracted from long term hycom reanalysis outputs the variability of the eddy induced intrusion were quantified the impacts of the cyclonic eddy and the anticyclonic eddy were opposite under the impact of cyclonic anticyclonic eddy the total onshore intrusion between 122 e and 124 e across the 200 m isobaths was decreased increased by 15 7 7 3 while the onshore intrusion west of 122 6 e and the northeastward current on the outer shelf was increased decreased by 30 6 4 7 and 31 10 1 respectively the arrival of cyclonic anticyclonic eddy brought positive negative potential vorticity pv flux and modulated the local ocean vertical stratification which weakened enhanced the cross slope pv gradient and the shelf slope constraint on the upper layer current therefore favored inhibited the kuroshio onshore intrusion this article is protected by copyright all rights reserved

analysis of terrestrial and martian volcanic compositions using thermal emission spectroscopy 1 determination of mineralogy chemistry and classification strategies we have examined and applied existing classification schemes for volcanic rocks and developed new schemes using thermal emission spectra of terrestrial volcanic rocks laboratory thermal infrared spectra 5 25 m at 2 cm 1 spectral sampling deconvolved modal mineralogies and derived mineral and bulk rock chemistries were used to distinguish basalt basaltic andesite andesite and dacite modal mineralogies derived from linear deconvolution of terrestrial volcanic rocks were compared to modes measured by an electron microprobe phase mapping technique to determine the accuracy of linear deconvolution in modeling specific mineral abundances one standard deviations of the absolute differences between modeled and measured mineral abundances range from 2 4 to 12 2 vol with an average standard deviation of 4 8 vol being in agreement with average uncertainties calculated in previous studies weighted average compositions of feldspars in the deconvolution generally overlap the measured ranges of plagioclase compositions and the presence of low calcium and high calcium pyroxenes was correctly identified bulk chemistries of volcanic rocks were derived with a relatively high degree of accuracy 1 standard deviations ranging from 0 4 to 2 6 vol by combining the compositions of spectrally modeled phases in proportion to their relative abundances in a particular sample these data were collectively used to examine existing and develop new volcanic rock classification schemes however no single classification scheme was effective in accurately classifying all samples multiple steps of classification were required to distinguish volcanic rocks reflecting the mineralogic diversity and continuum of compositions that exists in volcanic rock types in a companion paper hamilton et al this issue these schemes are applied to the classification of martian surface compositions

analysis of phyllosilicate deposits in the nili fossae region of mars comparison of tes and omega data abstract diverse phyllosilicate deposits discovered previously in the nili fossae region with near infrared reflectance data are a window into the complex history of aqueous alteration on mars in this work we used thermal infrared data from the thermal emission spectrometer tes in combination with near infrared data from the observatoire pour la mineralogie l eau les glaces et l activite omega to better constrain the mineralogy and geologic origin of these deposits we developed a tes spectral index for identification of clay minerals which correctly identifies the phyllosilicates in the nili fossae area and points to several other interesting deposits in the syrtis major region however detailed inspection of the tes spectral features of nili fossae phyllosilicates shows a feature at low wavenumbers 350 550 cm 1 that is not an exact match to any specific fe 3 al or mg rich phyllosilicate phase instead the feature is more similar to basaltic glass and may indicate that the phyllosilicates in this region are 1 rich in fe 2 based on similarity to trends seen in laboratory data of clay minerals 2 poorly crystalline extremely disordered and or 3 present within a matrix of actual basalt glass this feature is similar to spectral features seen in altered rocks in the columbia hills region of gusev crater by previous authors by calibrating measured spectral index values against mathematical spectral mixtures of typical martian dark surfaces and known abundances of alteration minerals we are able to estimate an enrichment in abundance of alteration minerals in the altered surfaces many dark noachian deposits in the nili fossae area are enriched phyllosilicates by 20 30 10 15 relative to dark volcanic surfaces in the same region the distribution and abundance of these phases indicates that alteration in the region was pervasive but did not completely erase the original mineralogy of what was likely an fe rich basalt protolith as a group the nili fossae phyllosilicate deposits are fundamentally different from those found in the mawrth vallis region nili fossae deposits have strong thermal infrared features related to admixed pyroxene plagioclase and occasionally olivine whereas the mawrth vallis deposits contain no mafic minerals comparison of tes and omega data also illustrates some more general differences between the datasets including the impact of physical character of the martian surface on detectability of minerals in each spectral range

the global topography of mars and implications for surface evolution elevations measured by the mars orbiter laser altimeter have yielded a high accuracy global map of the topography of mars dominant features include the low northern hemisphere the tharsis province and the hellas impact basin the northern hemisphere depression is primarily a long wavelength effect that has been shaped by an internal mechanism the topography of tharsis consists of two broad rises material excavated from hellas contributes to the high elevation of the southern hemisphere and to the scarp along the hemispheric boundary the present topography has three major drainage centers with the northern lowlands being the largest the two polar cap volumes yield an upper limit of the present surface water inventory of 3 2 to 4 7 million cubic kilometers

hydrogen isotope analyses of alteration phases in the nakhlite martian meteorites abstract secondary alteration phases such as carbonates smectite clays and fe oxides are found within the martian meteorites if these meteorites were seen to fall the assumption can be reasonably made that the secondary phases have a martian origin however for martian meteorite finds this is not the case deuterium hydrogen d h ratio analysis can be used to distinguish between terrestrial and martian secondary alteration phases the martian atmosphere is currently five times enriched in deuterium compared to terrestrial seawater producing a deuterium enrichment in the martian alteration phases large enough to be detected with modern ion microprobe techniques we aimed to measure the d h ratio of the iddingsite like alteration veins in the nakhlite martian meteorites nakhla mil 03346 mil 090030 and y 000593 to help confirm the martian origin of this material and determine the relative amounts of terrestrial contamination in each meteorite as an observed fall nakhla is nominally uncontaminated by terrestrial alteration and shows elevated d values in its alteration veins however even the highest of these values is much below that of the martian atmosphere indicating that terrestrial contamination probably combined with fractionation effects between the martian atmosphere and the alteration material have reduced the d values of these veins the speed of hydrogen isotope exchange in the nakhlite iddingsite like alteration veins is demonstrated by the purely terrestrial d values in the veins of nakhla 110 a thin section exposed to the terrestrial atmosphere since its preparation in 1998 mineralogical heterogeneity also affects the hydrogen isotope exchange rate in these veins the wide variation in d within the veins of nakhla and y 000593 appears to be due to the heterogeneous nature of the vein material where some phases exchange hydrogen with the atmosphere at a faster rate than others

a technique for mapping fe mg rich phyllosilicates on mars using themis multispectral thermal infrared images 1 we present a method for mapping exposures of fe mg rich phyllosilicates on the martian surface using themis daytime multispectral thermal infrared images the primary utility of this technique comes from the fact that themis coverage is near global at 100 m pixel so it offers the opportunity to extend and improve upon phyllosilicate maps created using crism and or omega near infrared data alone the spectral index formulation used for this mapping consists of a sum of spectral band ratios weighted in different proportions an initial formulation of the index was determined using a suite of synthetic spectra containing varying proportions of a martian basalt spectrum and a laboratory phyllosilicate spectrum a scene specific formulation was then optimized by exploiting the correlation between pixels the initial formulation flags in each themis scene as containing phyllosilicates and those identified in overlapping crism data once the optimal formulation of the index is determined it is applied to the entire themis scene extending the map of phyllosilicates beyond the area of overlapping crism coverage the method is illustrated using 12 themis scenes from the mawrth vallis and nili fossae regions the new themis derived maps of fe mg rich phyllosilicates in these two regions have approximately double the coverage provided by crism data the cross wavelength and cross instrument approach we use to derive phyllosilicate indices for themis data could potentially be used to define spectral indices for mapping other compositions of interest on mars that possess spectral features in more than one spectral region

super resolution of themis thermal infrared data compositional relationships of surface units below the 100 meter scale on mars abstract the thermal emission imaging system themis has provided the highest spatial resolution 100 m pixel thermal infrared tir data of the surface of mars to date these data have enabled the discovery of many small scale compositional units and helped to better constrain surface processes operating at these scales however with higher resolution visible vis instruments revealing smaller scale surficial differences there exists a need to detect and map compositional variability using tir data at scales below 100 m because it is unlikely there will be a higher resolution tir instrument sent to mars in the near future creative image processing techniques commonly classified under the umbrella of super resolution can be employed to improve or enhance the spatial resolution of the themis tir data these approaches typically integrate another higher resolution dataset and can either be qualitative for visual appeal quantitative for data accuracy or some combination of both the super resolution approach presented here produces enhanced tir images that are radiometrically accurate but also visually appealing for the technique to be successfully applied multi to hyper spectral data from two different spectral regions are required e g the themis tir and vis datasets the focus here is to introduce this new super resolution methodology and demonstrate its ability using existing themis ir and vis data the quartzofeldspathic deposit in northern syrtis major was selected because of the spectral variability detected using the original ir resolution data and to better constrain the relationship between the small scale surface morphology and areal extent of the deposit as well as its formation process despite being associated with the central peaks of two craters the results here show no positive correlation between the small rocky outcrops and the quartzofeldspathic unit a gradational contact exists between the unit and basaltic sands within the intercrater eolian material the super resolution approach offers an alternative approach to traditional sub pixel deconvolution identification and provides a higher resolution ir dataset for thermophysical and spectral analysis on mars

kuroshio meanders in the east china sea abstract an array of seven inverted echo sounders was moored along and across the kuroshio in the east china sea for more than one year the data from this array show evidence of energetic meanders with periods of 7 11 and 16 days the respective phase velocities of these meanders are 28 20 and 17 km day 1 downstream the 7 and 16 day waves are intermittent but the 11 day waves are present throughout the deployment the instability responsible for these waves is investigated with a spectral numerical model applied to a background state representing the kuroshio in this region the fastest growing instability from the model has e folding growth time of 2 days period of 12 days and phase velocity of 18 km day 1 downstream it appears to be a close representation of the 11 day wave seen in the observational data such a model has been previously used to represent meanders in the gulf stream at similar latitudes off the east coast of the united states the kuroshio meanders have approximately half the

claritas rise mars pre tharsis magmatism claritas rise is a prominent ancient noachian center of tectonism identified through investigation of comprehensive paleotectonic information of the western hemisphere of mars this center is interpreted to be the result of magmatic driven activity including uplift and associated tectonism as well as possible hydrothermal activity coupled with its ancient stratigraphy high density of impact craters and complex structure a possible magnetic signature may indicate that it formed during an ancient period of mars evolution such as when the dynamo was in operation as tharsis lacks magnetic signatures claritas rise may pre date the development of tharsis or mark incipient development since some of the crustal materials underlying tharsis and older parts of the magmatic complex respectively could have been highly resurfaced destroying any remanent magnetism here we detail the significant characteristics of the claritas rise and present a case for why it should be targeted by the mars odyssey mars reconnaissance orbiter and mars express spacecrafts as well as be considered as a prime target for future tier scalable robotic reconnaissance