coupled ice ocean dynamics in the marginal ice zones upwelling downwelling and eddy generation this study is aimed at modeling mesoscale processes such as upwelling downwelling and ice edge eddies in the marginal ice zones a two dimensional coupled ice ocean model is used for the study the ice model is coupled to the reduced gravity ocean model through interfacial stresses the parameters of the ocean model were chosen so that the dynamics would be nonlinear the model was tested by studying the dynamics of upwelling winds parallel to the ice edge with the ice on the right produce upwelling because the air ice momentum flux is much greater than air ocean momentum flux thus the ekman transport is greater under the ice than in the open water the stability of the upwelling and downwelling jets is discussed the downwelling jet is found to be far more unstable than the upwelling jet because the upwelling jet is stabilized by the divergence a constant wind field exerted on a varying ice cover will generate vorticity leading to enhanced upwelling downwelling regions i e wind forced vortices steepening and strengthening of vortices are provided by the nonlinear terms when forcing is time varying the advection terms will also redistribute the vorticity the wind reversals will separate the vortices from the ice edge so that the upwelling enhancements are pushed to the open ocean and the downwelling enhancements are pushed underneath the ice

nd and sr isotopic study of crustal and mantle inclusions from the sierra nevada and implications for batholith petrogenesis sm nd and rb sr systematics have been examined for eight upper mantle and lower crustal xenoliths the xenolith bearing trachyandesite and the granodiorite intruded by the trachyandesite in the sierra nevada batholith isotopic heterogeneity is shown by the xenoliths with 143 nd 144 nd ranging from 0 51169 to 0 51306 and 87 sr 86 sr ranging from 0 7031 to 0 7333 these ranges are similar to those of the plutonic rocks of the batholith this similarity suggests that the xenoliths believed to be representative of mantle and crustal reservoirs may approximate the diverse source regions from which the varied granitic rocks of the batholith were derived and that the sr nd isotopic correlation seen in granitic rocks may not be due to simple mixing of two end member components the subgranitic crust in this part of the sierra nevada apparently consists of metamorphosed sedimentary and igneous rocks which are highly variable isotopically the mantle beneath the sierra nevada is also isotopically heterogeneous both vertically and laterally

a soil chronosequence in northwestern italy morphological physical and chemical characteristics abstract a chronosequence of soils developed on fluvial terraces dating from lower middle pleistocene to upper upper pleistocene was studied to identify the morphological physical and chemical soil properties most sensitive to soil development and to further test the usefulness of iron oxides as indicators of relative age a relative horizon distinctness rhd index and the buntley westin and hurst colour indices clearly reflected differences in soil development with age among physical characteristics clay content and aggregation obtained by comparison of clay dispersion before and after removal of cementing agents were most efficient in indicating differences in duration of pedogenesis cation exchange capacity as related to clay content was the chemical property most useful to distinguish soils of different terraces iron oxide ratios were again useful as indices of soil development

a coupled ice ocean model of ice breakup and banding in the marginal ice zone a coupled ice ocean numerical model for the marginal ice zone is considered the model consists of a nonlinear sea ice model and a two layer reduced gravity ocean model the dependence of the upwelling response on wind stress direction is discussed the results confirm earlier analytical work it is shown that there exist directions for which there is no upwelling while other directions give maximum upwelling in terms of the volume of uplifted water the ice and ocean is coupled directly through the stress at the ice ocean interface an interesting consequence of the coupling is found in cases when the ice edge is almost stationary in these cases the ice tends to break up a few tenths of kilometers inside of the ice edge

parent material uniformity and degree of weathering in a soil chronosequence northwestern italy abstract the uniformity of the parent material and degree of weathering of the soils of a chronosequence developed during the pleistocene were investigated using optical microscopy x ray fluorescence and scanning electron microscopy sem techniques uniformity of the parent material was assessed by two criteria the ratios of resistant minerals and their specific elements in the heavy fraction s g 2 96 g cm 3 there was some variation between heavy mineral ratios but there was less variation between ratios from the chemical data and on this basis it was concluded that the parent material of each of the three soils in the sequence was uniform sem examination confirmed that the resistant minerals had remained unaltered although some ti bearing minerals showed some alteration the degree of chemical weathering as expressed by the ratio of mobile to non mobile elements and by parker s index increased from the youngest to the oldest soil

isotopic variation in the tuolumne intrusive suite central sierra nevada california granitoid rocks of the compositionally zoned late cretaceous toulumne intrusive suite in the central sierra nevada california have initial87sr 86sr values sri and143nd 144nd values ndi that vary from 0 7057 to 0 7067 and from 0 51239 to 0 51211 respectively the observed variation of both sri and ndi and of chemical composition in rocks of the suite cannot be due to crystal fractionation of magma solely under closed system conditons the largest variation in chemistry ndi and sri is present in the outer most equigranular units of the tuolumne intrusive suite sri varies positively with sio2 na2o k2o and rb concentrations and negatively with ndi al2o3 fe2o3 mgo feo cao mno p2o5 tio2 and sr concentrations this covariation of sri ndi and chemistry can be modeled by a process of simple mixing of basaltic and granitic magmas having weight percent sio2 of 48 0 and 73 3 respectively isotopic characteristic of the mafic magma are sri 0 7047 ndi 0 51269 and 18o 6 0 and of the felsic magma are sri 0 7068 ndi 0 51212 and 18o 8 9 the rocks sampled contain from 50 to 80 of the felsic component an aplite in the outer equigranular unit of the tuolumne intrusive suite apparently was derived by fractional crystallization of plagioclase and hornblende from magma with granudiorite composition that was a product of mixing of the magmas described above siliceous magmas derived from the lower crust having a maximum of 15 percent mantle derived mafic component are represented by the inner prophyritic units of the tuolumne intrusive suite

assessing parent material uniformity of a red and black soil complex in the landscapes abstract the distribution of red and black soil xeralfs xerolls associations in the monarto area south australia is complex and their genesis either being derived from a uniform parent material or a lithologic discontinuity is not known the objectives of this study were i to assess zr and ti bearing grains as minerals resistant to chemical weathering prior to employing zr and ti in determining parent material uniformity and ii to confirm whether pedological processes or a lithologic discontinuity may be responsible for the textural contrast within the red and black soil profiles scanning electron microscopy sem and energy dispersive x ray analysis edax were used to study chemical weathering and elemental composition of surfaces of zr and ti bearing grains x ray fluorescence xrf analysis was used to determine elemental concentrations in various soil fractions results showed that zr bearing grains consisted of only zircon having smooth clean surfaces which are characteristic of a mineral resistant to chemical weathering edax spectra confirmed that zr was a specific element to represent zircon suggesting its reliability to be used in assessing parent material uniformity on the other hand ti derived not only from minerals rutile anatase resistant but also from minerals ilmenite pseudorutile biotite susceptible to chemical weathering this limited the usefulness of ti as an index mineral for soil development studies except for zr ti ratio all other indicators of parent material uniformity i e depth distribution curves of zr and y in various fractions and y zr ratio showed no considerable inflection and variation with depth in a xeralf red soil this indicated the xeralf derived from a uniform parent material mica schists thereby texture contrast within a profile is due to pedological processes on the other hand depth distribution curves showed clear inflection and variation in xerolls black soils indicating soils developed from lithologic discontinuities so different trends in particle size fractions between 0 48 cm for ma5 and 0 59 cm for ma3 profiles compared to the underlying layers are due to parent material differences and not pedogenesis the presence of complex red and black soil association in the landscape is attributed to the difference in parent materials where the red soil developed from mica schist and the black soils from calcareous deposits

a tale of two plutons petrographic and mineralogic constraints on the petrogenesis of the red lake and eagle peak plutons central sierra nevada california the red lake and eagle peak plutons are similar in age k ar 87 89 m y and range in composition from granodiorite to granite the red lake pluton is equigranular has a locally greisened marginal zone and shows only minor mineralogical and chemical zoning whereas the eagle peak pluton is mineralogically compositionally and texturally zoned with an equigranular margin and a porphyritic core modal and normative trends within each pluton are consistent with separation of plagioclase and mafic minerals leading to a residual liquid enriched in quartz and alkali feldspar the formation of the prominent alkali feldspar megacrysts in the eagle peak core was promoted by plagioclase separation h 2 o undersaturation and a slower cooling rate relative to the red lake magma early loss of volatiles and a resulting increase in magma melt crystals viscosity inhibited crystal segregation within the red lake pluton and prevented the development of zoning late stage aplites associated with both plutons f

wind induced stratified ocean response in the ice edge region an analytical approach the response of a continuously stratified ocean to a moving ice edge is considered in terms of an analytical model it is assumed that the principal cause for the generation of such phenomena as upwelling near the edge is due to divergence in the across edge ekman transports the semi infinite ice cover is considered to act only as a modifier of an applied wind stress thus the ice edge is simulated by a discontinuity in the ocean surface stress distribution the results show that a stationary state relative to the moving edge develops the amplitude of the response is finite and it includes a system of standing waves relative to the edge these results parallel the generation of lee waves in a rotating wave regime how prominent the waves will be depends on the ratio u0 cn where u0 is the edge velocity and cn an eigenvalue corresponding to a vertical mode of the solution as the stationary solution builds up an along edge jet is established it is pointed out that this jet could cause divergence in the surface layer which could explain the generation of ice bands if the ice edge consists of broken ice

weathering of the new albany shale kentucky usa i weathering zones defined by mineralogy and major element composition abstract comprehensive understanding of chemical and mineralogical changes induced by weathering is valuable information when considering the supply of nutrients and toxic elements from rocks here minerals that release and fix major elements during progressive weathering of a bed of devonian new albany shale in eastern kentucky are documented samples were collected from unweathered core parent shale and across an outcrop excavated into a hillside 40 year prior to sampling quantitative x ray diffraction mineralogical data record progressive shale alteration across the outcrop mineral compositional changes reflect subtle alteration processes such as incongruent dissolution and cation exchange altered primary minerals include k feldspars plagioclase calcite pyrite and chlorite secondary minerals include jarosite gypsum goethite amorphous fe iii oxides and fe ii al sulfate salt efflorescence the mineralogy in weathered shale defines four weathered intervals on the outcrop zones a c and soil alteration of the weakly weathered shale zone a is attributed to the 40 a exposure of the shale in this zone pyrite oxidization produces acid that dissolves calcite and attacks chlorite forming gypsum jarosite and minor efflorescent salt the pre excavation active weathering front zone b is where complete pyrite oxidation and alteration of feldspar and organic matter result in increased permeability acidic weathering solutions seep through the permeable shale and evaporate on the surface forming abundant efflorescent salt jarosite and minor goethite intensely weathered shale zone c is depleted in feldspars chlorite gypsum jarosite and efflorescent salts but has retained much of its primary quartz illite and illite smectite goethite and amorphous fe iii oxides increase due to hydrolysis of jarosite enhanced permeability in this zone is due to a 14 loss of the original mass in parent shale denudation rates suggest that characteristics of zone c were acquired over 1 ma compositional differences between soil and zone c are largely attributed to illuvial processes formation of additional fe iii oxides and incorporation of modern organic matter

uranium lead isotopic ages from the sierra nevada batholith california this study provides new information on the timing and distribution of mesozoic magmatic events in the sierra nevada batholithic complex chiefly between 36 and 37 n latitude u pb ages have been determined for 133 zircon and 7 sphene separates from 82 samples of granitoid rocks granitoid rocks in this area range in age from 217 to 80 m y triassic intrusions are restricted to the east side of the batholith jurassic plutons occur south of the triassic plutons east of the sierra nevada as isolated masses within the cretaceous batholith and in the western foothills of the range cretaceous plutons form a continuous belt along the axis of the batholith and occur as isolated masses east of the sierra nevada no granitic intrusions were emplaced for 37 m y east of the sierra nevada following the end of jurassic plutonism however following emplacement of the eastern jurassic granitoids regional extension produced a fracture system at least 350 km long into which the dominantly mafic calc alkalic independence dike swarm was intruded 148 m y ago the dike fractures probably represents a period of regional crustal extension caused by a redistribution of the regional stress pattern accompanying the nevadan orogeny intrusion of cretaceous granitic plutons began in large volume about 120 m y ago in the western sierra nevada and migrated steadily eastward for 40 m y at a rate of 2 7 mm y this slow and constant migration indicates remarkably uniform conditions of subduction with perhaps downward migration of parent magma generation or a slight flattening of the subduction zone such steady conditions could be necessary for the production of large batholithic complexes such as the sierra nevada the abrupt termination of plutonism 80 m y ago may have resulted from an increased rate of convergence of the american and eastern pacific plates and dramatic flattening of the subduction zone u pb ages of the giant forest alaskite sequence in sequoia national park are all in the range 99 3 m y indicating a relatively short period of emplacement and cooling for this nested group of plutons u pb ages of a mafic inclusion and its host granodiorite indicate that both were derived from a common source or that the mafic inclusion was totally equilibrated with the granodioritic magma comparison of isotopic ages determined by different methods such as zircon u pb sphene u pb hornblende k ar and biotite k ar suggests that zircon u pb ages generally approximate the emplacement age of a pluton however some plutons probably contain inherited or entrained old zircons and the zircons of some samples are disturbed by younger thermal and metamorphic events the ages reported here are consistent with u pb age determinations previously made on granitic rocks to the north stern et al 1981 the age distribution of granitic belts determined here is in general agreement with those established by k ar dating evernden and kistler 1970 but does not differentiate the five epochs of plutonism determined in their study

ice banding as a response of the coupled ice ocean system to temporally varying winds in this study we model formation of ice bands in the marginal ice zones a one dimensional coupled ice ocean model is used in which the ice model is coupled to a reduced gravity ocean model through interfacial stresses the internal ice stresses are important only at high ice concentrations 90 100 otherwise the main balance for the ice motion is between the air ice stress and the ice water stress i e free drift the drag coefficients were chosen so that the air ice momentum flux is 3 times greater than the air ocean momentum flux thus the ekman transport is larger under the ice than in the open water so that winds parallel to the ice edge with the ice on the right produce upwelling the upwelling simulation was extended to include temporally varying forcing which was chosen to vary sinusoidally with a 4 day period this forcing resembles successive cyclone passings perpendicular to the ice edge when the oceanic upper layer was thin which means that the dynamics are strongly nonlinear the ice bands were formed the up downwelling signals do not disappear in wind reversals because of nonlinear advection this leads to convergences and divergences in oceanic and ice velocities that manifest themselves as ice banding at least one wind reversal is needed to produce one ice band

scanning electron microscope study of zircons and rutiles from a podzol chronosequence at cooloola queensland australia summary a chronosequence of four soils derived from aeolian deposited sand at cooloola along the eastern coast of southern queensland has been studied to document predepositional and pedogenic changes in zircon and rutile grains in the fine sand fraction 53 125 m with increasing soil age the soils range in age from holocene typic quartzipsamment presently drifting sand to mid pleistocene spodic quartzipsamment 90 ka bp parent materials are moderately stratified sands with irregular depositional layers in places having high concentration of heavy mineral grains scanning electron microscopy was used to characterize grain surface microtexture by a semi quantitative method based on frequency of occurrence of ten classes of surface microtextures pedogenic changes were quantified and differences between horizons in the same profile between different profiles within the same horizon and between minerals were tested for significance using the 2 distribution zircon grains are less chemically weathered during pedogenesis than rutile possibly due to the higher iron content of the latter however zircons tend to show more features which can be associated with physical alteration rutile grains in the illuviated b2hs horizons of the troporthod and spodic quartzipsamments are more thickly coated with poorly crystalline iron and alumino silicate compounds compared with zircon grains and the presence of grain coatings does not seem to have prevented the surfaces of grains from developing solution pits with increasing age there is a preponderance of weathering features on grains of both minerals the presence of various shapes and surface microtextures on grains from the different soils suggests a multiple grain source for zircon and rutile and a complex predepositional history for these minerals nevertheless microtextural features of zircons and rutiles are valuable for the interpretation of the extent and nature of post depositional weathering

the partition of air ice ocean momentum exchange as a function of ice concentration floe size and draft a coupled sea ice ocean model is used to examine the relative magnitudes of terms in the sea ice momentum equation for ice concentrations less than 100 this numerical model for steady state horizontally homogeneous flow includes two terms that have previously been neglected in such quantitative models these are oceanic form drag and wave radiation pressure both of which are lateral forces that act on the sides of floes the former is generally decelerative while the latter is accelerative the model accepts as input variables average ice draft areal concentration and floe diameter it is found that form drag can be greater than or of the same order as skin friction drag for small thick floes at low concentrations an exception to this rule occurs when the effect of wakes between floes reduces the local form drag the higher net drag that generally exists at low concentrations implies lower ice floe speeds wave radiation pressure is negligible in all cases although this is sensitive to our choice of fetch parameterization ocean drag is often parameterized in numerical models of sea ice as a skin friction term alone with a constant drag coefficient between ice and prescribed geostrophic current velocities results from the present model are plotted in terms of such a drag coefficient which is a function of concentration floe size and draft this could be useful in future work where floe size data become regularly available for instance from radar satellite imagery

oceanographic conditions in the marginal ice zone north of svalbard in early fall 1979 with an emphasis on mesoscale processes during september october 1979 the norwegian remote sensing experiment was carried out in the marginal ice zone north of svalbard convergence of the ice cover is correlated with along ice edge winds with the ice to the right while divergence occurs during office winds or calm conditions a wind driven ice edge jet is observed wind driven upwelling of the pycnocline of up to 7 m was present along the ice edge during a 10 to 15 m s easterly wind event the upwelling is due to ekman divergence at the ice edge caused by higher wind stress over ice than over open water the ice edge meanders with a scale of 20 40 km and sheds eddies with a scale of 5 to 15 km into the open water this scale is of the same order as the rossby radius of deformation eddies with the same scale are also seen in the conductivity temperature and depth observations conditions during the experiment were such that barotropic instabilities could have generated these eddies

sensitivity studies with a coupled ice ocean model of the marginal ice zone an analytical coupled ice ocean model is considered which is forced by a specified wind stress acting on the open ocean as well as the ice the analysis supports the conjecture that the upwelling dynamics at ice edges can be understood by means of a simple analytical model in similarity with coastal problems it is shown that the ice edge upwelling is determined by the net mass flux at the boundaries of the considered region the model is used to study the sensitivity of the upwelling dynamics in the marginal ice zone to variation in the controlling parameters these parameters consist of combinations of the drag coefficients used in the parameterization of the stresses on the three interfaces atmosphere ice atmosphere ocean and ice ocean the response is shown to be sensitive to variations in these parameters in that one set of parameters may give upwelling while a slightly different set of parameters may give downwelling

feedback between ice flow barotropic flow and baroclinic flow in the presence of bottom topography coupling between externally driven barotropic flow and locally driven baroclinic flow in the presence of an ice cover and topography is studied the topography is a necessary ingredient in this coupling this study shows that the observed mesoscale activity of the ice edge seen in satellite imagery does not necessarily reflect the mesoscale baroclinic activity in the ocean besides oceanic eddies the ice cover can trace the topographic changes via the coupling to the barotropic flow a two layer ocean model coupled to an ice model is constructed to simulate an ice ocean system with a varying bottom topography in the absence of wind forcing the ice cover reflects the externally driven barotropic ocean response especially topographically forced taylor columns by forming ice streamers or meanders some of these features propagate advected with the ocean currents as a whole downstream creating an image of eddy propagation even though there is no baroclinic structure underneath when downwelling favorable winds ice on the left from the wind direction are turned on in addition to this background barotropic flow the ekman flow in the ocean toward the open ocean will enhance the meandering of the ice edge due to the barotropic flow during upwelling favorable winds the ice edge stays rather compact including the case when a strong baroclinic cyclonic vortex is developing beneath an ice meander supported by the taylor column in the ocean

geochemistry of soils of king george island south shetland islands west antarctica implications for pedogenesis in cold polar regions fine fractions of soils on the barton peninsula king george island west antarctica have been forming during the last 6000 yr since the last deglaciation texturally they are mostly composed of mineral and rock fragments with some volcanic ashes which are also indicated by geochemical compositions representing for the nonclay silicate minerals and low values of chemical index of alteration no significant changes are observed in major and trace element abundances such geochemical characteristics suggest that chemical weathering of bedrocks on the barton peninsula seems insignificant and that the soils are composed of physically weathered mineral and rock fragments which are mixed with eolian additions of volcanic ashes and patagonian dusts chondrite normalized rare earth element ree distribution patterns of the barton peninsula soils are slightly different from those of bedrocks indicating that the ree abundances and characteristics were influenced by eolian additions mixing calculations which mass balance the rees suggest that volcanic ashes blown from deception island were the major eolian contributor followed by atmospheric dusts sourced from patagonia south america even in the warmer and humid climatic conditions in the maritime antarctic region the chemical weathering of bedrocks appears to be insignificant probably due to the relatively short duration of weathering since the last deglaciation

stable isotope systematics in mesozoic granites of central and northern california and southwestern oregon 18o d and h2o contents were measured for whole rock specimens of granitoid rocks from 131 localitics in california and southwestern oregon with 41 new determinations in the klamath mountains and sierra nevada initial strontium isotope ratios are known for 104 of these samples large variations in 18o 5 5 to 12 4 d 130 to 31 water contents 0 14 to 2 23 weight percent and initial strontium isotope ratios 0 7028 to 0 7095 suggest a variety of source materials and identify rocks modified by secondary processes regular patterns of variation in each isotopic ratio exist over large geographical regions but correlations between the ratios are generally absent except in restricted areas for example the regular decrease in d values from west to east in the sierra nevada batholith is not correlative with a quite complex pattern of 18o values implying that different processes were responsible for the isotopic variations in these two elements in marked contrast to a good correlation between 87sr 86sr o and 18o observed in the peninsular ranges batholith to the south such correlations are lacking except in a few areas d values on the other hand correlate well with rock types chemistry and 87sr 86sr o except in the coast ranges where few of the isotopic signatures are primary the uniformly low d values of samples from the mojave desert indicate that meteoric water contributed much of the hydrogen to the rocks in that area even so the 18o values and 18o fractionations between quartz and feldspar are normal in these same rocks

an observational and numerical study of wind stress variations within marginal ice zones published studies of ocean mesoscale processes in marginal ice zones mizs using numerical coupled ice ocean models usually assume that the surface wind speed is constant over the model domain and that wind stress variations are simply proportional to surface roughness variations we show that this assumption is not realistic in most situations because the surface wind stress is also significantly affected by mesoscale pressure variations by changes in the surface wind vector and by changes in surface layer stability two numerical case studies utilizing detailed surface and atmospheric measurements examine the factors affecting small scale 5 km variations in wind stress within mizs these case studies and surveyed observational and modeling results demonstrate that wind stress fields are qualitatively different from the surface roughness fields a realistic wind stress scenario consists of a maximum just inside the ice edge and another maximum in the open ocean stress minima occur within the pack ice region away from the miz and over grease ice if present the effect of the rougher miz ice is counteracted when wind stresses over the open ocean are enhanced by large surface heat fluxes over the ocean by a strong low level inversion over the ice or by a sharp atmospheric front with surface winds paralleling the ice edge such situations are common in miz regions some simple methods for including first order atmospheric effects on wind stress variations which could be incorporated into current ice ocean mesoscale models of miz regions are suggested

a coupled ice ocean model of upwelling in the marginal ice zone a dynamical coupled ice ocean numerical model for the marginal ice zone miz is suggested and used to study upwelling dynamics in the miz the nonlinear sea ice model has a variable ice concentration and includes internal ice stress the model is forced by stresses on the air ocean and air ice surfaces the main coupling between the ice and the ocean is in the form of an interfacial stress on the ice ocean interface the ocean model is a linear reduced gravity model the wind stress exerted by the atmosphere on the ocean is proportional to the fraction of open water while the interfacial stress ice ocean is proportional to the concentration of ice a new mechanism for ice edge upwelling is suggested based on a geostrophic equilibrium solution for the sea ice medium the upwelling reported in previous models invoking a stationary ice cover is shown to be replaced by a weak downwelling due to the ice motion most of the upwelling dynamics can be understood by analysis of the divergence of the across ice edge upper ocean transport on the basis of numerical model an analytical model is suggested that reproduces most of the upwelling dynamics of the more complex numerical model

warm water cells in the north water northern baffin bay during winter sea surface temperatures above the freezing point of seawater 1 8 c were observed in the north water during winter and early spring the result indicates a possibility of upwelling warm water presumably of atlantic origin brought from lower depths to the surface the warm water temperatures ranged from 1 7 to 0 1 c the highest occurrence frequency lay in the temperature interval from 1 0 to 0 8 c most warm water cells were found along the greenland coast in smith sound lady ann strait and barrow strait they occurred most frequently in smith sound west of cape alexander the highest temperatures of 0 1 c occurred however south of cape alexander the occurrence frequency and the total area of warm water patches decreased toward spring the predominantly northerly wind that is channeled in smith sound accounts for a mean ice drift of approximately 17 km d 1 this ice drift causes an ice divergence in smith sound and along the greenland coast the existence of warm water areas can be explained by the strong northerly wind resulting in a coriolis force that induces coastal upwelling the wind induced offshore transport of 3 5 105 m3 s 1 in the north water compensated by the upwelling of atlantic baffin bay water 0 c along the greenland coast will suffice to keep 10 of the north water ice free the combination of ice divergence and forced convection of warm water can be considered as a prime cause of the polynyas in the north water

a two dimensional coupled ice ocean model of the bering sea marginal ice zone a two dimensional coupled ice ocean model has been formulated and applied to the wintertime bering sea marginal ice zone the oceanic component is a multilevel model that incorporates second moment closure for turbulent mixing in the water column the ice cover is modeled as a viscous plastic continuum melting at the ice ocean interface is computed using well known lawof the wall concepts in a turbulent boundary layer with particular attention to the disparate momentum and scalar transfer resistance coefficients over rough walls the thermodynamic and dynamical interactions between the ocean and the ice cover and the energy balances at the air ice and air sea interfaces are modeled according to the companion paper mellor and kantha this issue the model incorporates barotropic tides both diurnal and semidiurnal for application to the bering shelf double diffusive fluxes across the interface between the colder fresher layer beneath the melting ice and the warmer more saline water underneath are prescribed from laboratory data on double diffusive convection during winter sea ice in the central bering sea is transported toward the shelf break by off ice winds where it encounters northward flowing warmer north pacific waters and melts it is this situation to which the two dimensional model has been applied by neglecting all variations in the along ice edge direction the water conditions downstream of the ice edge the ice conditions upstream and the wind stress are the primary inputs to the model the model simulates transition from ice covered to open ocean conditions and the associated ice edge front and the two layer circulation underneath the ice cover sensitivity studies indicate that the density structure and the circulation beneath the ice and the position of the ice edge are rather sensitive to the parameters affecting the dynamics and the thermodynamics of the coupled ice ocean system even small changes in the relevant parameters can cause a substantial retreat or advance of the ice edge which may help explain why marginal ice zones are such dynamically active regions

wave effects on ocean ice interaction in the marginal ice zone the effects of wave train on ice ocean interaction in the marginal ice zone are studied through numerical modeling a coupled two dimensional ice ocean model has been developed to include wave effects and wind stress for the predictions of ice edge dynamics the sea ice model is coupled to the reduced gravity ocean model through interfacial stresses the main dynamic balance in the ice momentum is between water ice stress wind stress and wave radiation stresses by considering the exchange of momentum between waves and ice pack through radiation stress for decaying waves a parametric study of the effects of wave stress and wind stress on ice edge dynamics has been performed the numerical results show significant effects from wave action the ice edge is sharper and ice edge meanders form in the marginal ice zone owing to forcing by wave action and refraction of swell system after a couple of days upwelling at the ice edge and eddy formation can be enhanced by the nonlinear effects of wave action wave action sharpens the ice edge and can produce ice meandering which enhances local ekman pumping and pycnocline anomalies the resulting ice concentration pycnocline changes and flow velocity field are shown to be consistent with previous observations

the interaction of an ocean eddy with an ice edge ocean jet in a marginal ice zone remotely sensed images in the east greenland current marginal ice zone region indicate a variety of mesoscale motions these range from isolated monopoles and dipoles to multiple eddy fields recent observations indicate that many of the eddies may be advected into the region from the west spitsbergen current region they then interact with the east greenland current marginal ice zone and its associated along ice edge jet in this paper we illustrate how the ice floe fields can evolve during the interaction of an ocean eddy with an along ice edge ocean jet the effects of eddy sense of rotation flow strength and bottom topography are considered in barotropic and baroclinic two layer numerical experiments initially barotropic experiments involve the combined effects of flat bottom eddy jet interactions and eddy topography interactions over a flat bottom anticyclones interact with the cyclonically sheared side of the jet and move seaward exporting ice away from the ice edge in a dipolar distribution cyclones move toward the jet and are advected downstream a second dipole formation mechanism is associated with eddy topography interaction and is a consequence of the shallow pycnocline depth of the region rapid topographic rossby wave radiation in the lower layer spreads energy along slope and upslope downslope for cyclones anticyclones the upper ocean response to this process is a dipole which propagates parallel to the ice edge with shallow water to the left topographic eastward jet induced and topography induced eddy propagation tendencies combine to enhance cyclone jet interaction and limit anticyclone jet interactions the dipole formation associated with eddy topography interaction is weakened by the presence of the jet but not eliminated eddy induced distortions in the ice edge are suppressed by the stabilizing effect of topography on the jet sensitivity of the initially barotropic results to variation in the rossby number and degree of topographic slope illustrates that eddies are more efficient in producing ice edge distortions for stronger flows and weaker topographic slopes for initially baroclinic simulations over topography results are comparable to flat bottom cases strong upper layer eddy jet interactions can occur independent of topographic effects which are constrained to the lower layer

two mica granites of northeastern nevada the field settings are described and analytical data are presented for six two mica granites from north eastern nevada high 18o and 87sr 86sr values indicate that all are s type granites derived from continental crust the major element chemistry and accessory mineral contents of these rocks also are characteristic of s type granites chemical x ray and other data are presented for the micas recovered from these granites the muscovites are notably high in fe2o3 feo and mgo except for one hydrobiotite each of the biotites has an mgo content near 6 0 weight percent two different types of two mica granites are recognized in the area of this study one type is distinguished by the presence of many biotite euhedra within muscovite phenocrysts and by an unusual suite of accessory minerals completely devoid of opaque oxides this type probably resulted from anatexis of late precambrian argillites under conditions of relatively low oxygen fugacity along a line that roughly coincides with the westward disappearance of continental basement in the other textural type of two mica granite the micas are equigranular and there is a greater variety of accessory minerals the magmatic evolution of this type also appears to reflect the influence of late precambrian argillites there may be age differences between the two types of two mica granites