air sea interactions over terra nova bay during winter simulation with a coupled atmosphere polynya model a preliminary simulation of the terra nova bay polynya has been performed with a coupled atmosphere polynya model the atmospheric model is a hydrostatic primitive equations model that has been validated previously by a simulation of the strong katabatic winds observed in that area the polynya model includes a representation of the free drift of frazil ice and simple sea ice dynamics and thermodynamics two and three dimensional experiments have been performed under polar night conditions two dimensional experiments show that an open warm water area influences significantly the atmospheric circulation in the antarctic coastal zone an additional ice breeze effect is simulated and is responsible for the strenghthening of the katabatic winds near the coast because of the important temperature difference between the continental air and the ice free ocean up to 40 c strong surface heat fluxes are simulated over the polynya finally a three dimensional experiment has been performed the integration domain includes terra nova bay the polynya observed in that region is well simulated it is found that heat losses from the polynya surface are stronger than previously thought but are probably constrained by the idealized representation of frazil ice which is assumed to be uniform in each grid box this stresses the need for having a better knowledge of frazil ice evolution in large polynyas

surface airflow around windless bight ross island antarctica ross island antarctica is located along the transantarctic mountains and is subjected to a strong southerly mountain parallel wind regime despite this windless bight on the island s southern coast is a region of anomalous calm the atmospheric boundary layer dynamics that gives rise to this phenomenon is analysed both theoretically and observationally it is the strong static stability of the boundary layer air encountering the high steep topography of ross island that causes a stagnation zone resulting in the calm conditions of windless bight direct and proxy observations of boundary layer winds provide a detailed description of airflow around the island the anomalous with respect to the synoptic pressure field but persistent north easterly winds at scott base are due to the deflection of highly stable low level air around hut point peninsula by contrast the less frequent strong southerly winds which override the peninsula are associated with the influx of warm maritime air from cyclonic systems to the east it is inferred that flow of air around the terrain of ross island gives rise to locally strong winds these are responsible for the ice breakout and polynya occurrences in mcmurdo sound the surface airflow past ross island can be modelled by a two dimensional steady frictionless irrotational incompressible flow past an obstacle with a shape based on an island height contour the flow is assumed to separate from the eastern and western sides of the island and form a wake downstream a solution for this flow is presented based on potential theory for streaming motion past an obstacle the streamline and isobar patterns clearly depict the stagnation region in windless bight for approaching winds of 20 ms 1 the local pressure field is perturbed by several millibars

the confluence zone of the intense katabatic winds at terra nova bay antarctica as derived from airborne sastrugi surveys and mesoscale numerical modeling the surface wind field inland of the intense coastal kataba c wind regime at terra nova bay antarctica has been studied both observationally and numerically airborne surveys of windinduced features on the snow surface have been used to construct the time averaged winter surface airflow pattern the surface motion field has also been simulated by a mesoscale primitive equation model using terrain slopes with a horizontal resolution of 32 km both methods of analys s demonstrate that the intense katabatic airstream at terra nova bay is forced by converging air currents in the continental interior the broadscale confluence zone becomes organized into two regions within about 180 km of the coast the primary route for katabatic mass transport into the terra nova bay area is reeves glacier valley but an important secondary source is provided by airflow down david glacier the former is generated by the coriolis induced concentration of mass transport on the left side looking downwind of the broadscale confluence zone as well as by the near coastal mountain deflection of airflow into the valley head the confluence zone feeding into david glacier valley stretches over 100 km into the interior and is forced by the broadscale terrain configuration of the ice sheet source areas for the two airstreams differ with reeves glacier valley being fed by cold air formed well into the interior whereas the airflow down david glacier is sustained by radiative cooling over lower parts of the ice sheet which are much closer to the ross sea evaluation of the observational and modeling results reveals both the strengths and weaknesses of each approach airborne surveys of sastrugi orientations are a highly successful method for establishing the detailed pattern of surface airflow however a systematic examination of sastrugi dimensions suggests that such work could also be carried out using spot type satellite observations which is a more cost effective approach than aircraft surveying the double jet structure of katabatic airflow into the terra nova bay area is well represented by the primitive equation modeling but much finer grids are needed to resolve the near coastal drainage details

infrared microspectroscopy analysis of water distribution in deformed and metamorphosed rocks infrared microspectroscopy has been applied to thin sections of various deformed and metamorphosed rocks in order to investigate water content of quartz in these rocks the broad ir band absorbance around 3400 cm 1 probably due to fluid inclusion molecular water h2o was used to calculate water contents deformed granitic rocks from the yanazawa kamimura area near the median tectonic line mtl showed an increase of water content in quartz from about 300 ppm to 2500 ppm toward the mtl with increasing degree of deformation metacherts from sambagawa metamorphic rocks asemigawa route showed a systematic decrease of water content in quartz from about 1000 ppm to 200 ppm with increasing metamorphic degree from chlorite garnet albite biotite to oligoclase biotite zones an archaean metachert from the napier complex granulite facies has only 40 ppm water comparing this with an inuyama unmetamorphosed chert sample having water contents of 3500 to 7000 ppm a starting point of metamorphism the systematic decrease of water in quartz with increasing metamorphic grade may extend from unmetamorphosed cherts to the highest grade metacherts water contents in high pressure metamorphic rocks in japan are mostly of the order of 500 ppm 300 700 ppm except for those from kurosegawa with a water content as high as 1700 ppm these results represent an exploratory analysis of intragranular water contents in quartz in various deformed and metamorphosed rocks further micro ft ir studies of the distribution of water in crustal rocks will provide a quantitative basis for examining the geochemical cycle of water in the earth s crust

deformation processes at the down dip limit of the seismogenic zone the example of shimanto accretionary complex in order to constrain deformation processes close to the brittle ductile transition in seismogenic zone we have carried out a microstructural study in the shimanto accretionary complex japan the fossil equivalent of modern nankai accretionary prisms the hyuga tectonic melange was sheared along the plate interface at mean temperatures of 245 c 30 c as estimated by raman spectroscopy of carbonaceous material rscm it contains strongly elongated quartz ribbons characterized by very high fluid inclusions density as well as micro veins of quartz both fluid inclusion planes and micro veins are preferentially developed orthogonal to the stretching direction furthermore crystallographic preferred orientation cpo of quartz c axes in the ribbons has maxima parallel to the stretching direction recrystallization to a small grain size is restricted to rare deformation bands cutting across the ribbons in such recrystallized quartz domains cpo of quartz c axes are orthogonal to foliation plane the evolution of deformation micro processes with increasing temperature can be further analyzed using the foliated morotsuka a slightly higher grade metamorphic unit 342 30 c by rscm from the shimanto accretionary complex in this unit in contrast to hyuga tectonic melange recrystallization of quartz veins is penetrative cpo of quartz c axes is concentrated perpendicularly to foliation plane these variations in microstructures and quartz crystallographic fabric reflect a change in the dominant deformation mechanism with increasing temperatures above 300 c dislocation creep is dominant and results in intense quartz dynamic recrystallization in contrast below 300 c quartz plasticity is not totally activated and pressure solution is the major deformation process responsible for quartz ribbons growth in addition the geometry of the quartz ribbons with respect to the phyllosilicate rich shear zones shows that bulk rheology is controlled by quartz behavior consequently below 300 c the application of quartz pressure solution laws based on realistic geometry derived from hyuga microstructures results in strongly lowering the overall strength of the plate interface with respect to the classical brittle envelop

cross equatorial response to middle latitude forcing in a zonally varying basic state abstract a nonlinear model based on the shallow water equations is used to study cross equatorial propagation of forced waves in the presence of a longitudinally varying time mean basic state zonal wind field it is found that global scale planetary waves are unable to propagate past a critical latitude where the mean zonal wind speed vanishes however if the longitudinally asymmetric basic state includes a duet in which the zonal winds are westerly waves of zonal scale less than the zonal scale of the westerly duct may propagate from one hemisphere to the other even though the zonally symmetric mean zonal wind remains easterly in the equatorial region the amplitude of the response in one hemisphere to forcing in the opposite hemisphere increases strongly with the magnitude of the westerlies in the equatorial duct the existence and annual variations of a westerly duct region in the upper troposphere in the eastern pacific appear to account for some features of the low frequency variability in the no

on the forcing of planetary scale rossby waves by antarctica the propagation of rossby waves forced at high latitudes into middle and low latitudes is studied using the barotropic vorticity equation on the sphere ray tracing theory indicates that fundamental differences exist between the response of an atmosphere initialized with typical northern hemisphere winter flow and typical southern hemisphere winter flow to such a forcing with a substantial response more likely for the southern hemisphere case integrations with a fully nonlinear barotropic model confirm this suggestion and indicate that away from the local forcing region linear theory provides a good description of the response the most notable feature in the steady solutions is a split of the mid latitude jet close to new zealand the location of this split coincides well with a region where blocking is observed to be prevalent in the southern hemisphere

water distribution in low grade siliceous metamorphic rocks by micro ftir and its relation to grain size a case from the kanto mountain region japan abstract infrared microspectroscopy reveals that liquid like water is always present in polycrystalline quartz grains from low grade metamorphic cherts and shale in the chichibu group and the mikabu greenrock complex of the kanto mountains area the water distribution in these rocks is heterogeneous and is related to rock textures in the microcrystalline quartz o h species due possibly to si oh are generally present the liquid like water is also present at grain boundaries and or in sub micron fluid inclusions in the microcrystalline parts on the other hand in quartz grains larger than 20 m in diameter within veins only the liquid like water is present possibly as fluid inclusions trapped during quartz vein formation in the microcrystalline cherty matrix of the metamorphic rocks a general decrease in liquid like water content is observed with increasing metamorphic grade associated with an increase in grain size two representative grain shapes a cube and a regular tetradecahedron having 14 planes are used to estimate the surface area between grains per unit volume with the grain size d m 3 d for cubic and 2 37 d for tetradecahedron grain boundary volumes were then calculated assuming grain boundary widths from 0 5 to 20 nm and normalized by unit volume of the rock the measured ir data on low grade metamorphic cherty rocks fall closely on these curves with grain boundary width of around 10 nm for the both models assuming saturation of h2o at grain boundary the observed decrease in water content with increase in grain size can be rigorously explained by the decrease in grain boundary volume per unit volume these results suggest that liquid like water occurs mainly between grain boundaries in the microcrystalline quartz of low grade metamorphic rocks although this grain boundary water model is the first approximation and requires further details of quantitative grain boundary textures the present model can provide a new approach to understand water distribution in polycrystalline rocks

morphology of intergranular pores and wetting angles in pelitic schists studied by transmission electron microscopy in pelitic schists composed mainly of quartz and albite grains the morphology of intergranular pores which were filled with water was studied by transmission electron microscopy tem although some pores are defined by crystallographic planes f face most of their form has an ideal shape determined by interface tensions between grains and fluid high resolution tem observations demonstrate that pore free regions at grain boundaries are tight even at the nanometer scale showing that the wetting angle is larger than 0 in this rock the pore distribution in two grain junctions can be compared to a necklace microstructure developed by instability of a fluid film along the boundary induced by microcracking wetting angles for pores located at grain edges of quartz and albite decrease in the order albite albite quartz quartz and quartz albite the quartz quartz wetting angle in a calcite free sample is smaller than that in a calcite containing sample this angle also changes due to grain misorientation our results confirm that solid solid and solid fluid interfacial energies control the geometry of intergranular fluid in natural rocks

linear wavetrains in models of the stratosphere experiments with a primitive equation model of the stratosphere and mesosphere are described which investigate the effect on the stratosphere of the growth of localized stationary forcing in the troposphere two basic states are used which are representative of stratospheric flow in early and late winter in the southern hemisphere simple mechanistic models are then introduced to examine the wave phenomena which occur during the first 10 days of the experiments when the dynamics are known to be linear the localized forcing grows to a peak amplitude of 600 gpm and half width of 15 of latitude values typical of the mid latitude upper troposphere stratospheric travelling waves are excited with phase velocities which are sensitive to the zonal mean winds and to the speed of the switch on of the forcing and wave activity spreads quickly from the localized forcing with a typical vertical group velocity of 10 km d 1 strong horizontal curvature in the basic states can profoundly affect the vertical and horizontal structures of the wavetrains mid latitude regions of negative northward potential vorticity gradient in the stratosphere as seen in the southern hemisphere in late winter lead to the confinement and amplification of waves in high latitudes three dimensional diagnostics of wave activity propagation reveal wave reflections missed by zonally averaged ep flux diagnostics significant wave reflection and trapping occur on the flow from late winter eventually producing a steady linear wavetrain with an intense local centre of circulation in the upper stratosphere the maximum anomaly being 1000gpm at 1mb it is argued that such wavetrains are unrealistic because nonlinear ageostrophic winds drive the dynamics away from any linear steady state

an observational study of traveling planetary waves in the southern hemisphere abstract southern hemisphere analyses from the surface to 2 mb and from 20 to 80 s for the period may september 1979 have been used to study the structure of traveling planetary waves space time cross spectral analysis of the height field has been employed to define the amplitude and phase for both the eastward and westward moving components of particular combinations of zonal wavenumber and frequency band latitude height contour plots of power phase and coherence squared show that westward moving waves have structure characteristic of barotropic external modes and are coherent across a broad range of latitudes and from the surface to 2 mb the highest level analyzed eastward moving waves on the other hand have more rapid phase variations especially in the troposphere and appear more baroclinic the tropospheric structure of the moving components of wavenumbers 1 4 is as one would expect for baroclinically unstable modes of the charney type wavenumbers 1 and 2 both have double amplitude maxima i

enso influences on southern hemisphere column ozone during the winter to spring transition 1 this study investigates how the el nino southern oscillation enso modulates the distribution of column ozone during the southern hemisphere sh winter to spring transition when a zonal asymmetry in column ozone develops near 55 s with a maximum south of australia enso differences in column ozone and planetary wave structure are explored for the average of seven el nino en versus six la nina ln events during 1982 2004 a westward shift in convection during ln corresponds to a 30 50 westward shift of sh planetary wave and column ozone patterns the extratropical lower stratospheric temperature anomalies are inversely correlated with tropical anomalies in similar longitude bands and are highly correlated with local column ozone anomalies the tropical signal is communicated to higher latitudes by modulating subtropical anticyclones with distinctive responses for en and ln years for each month during august and en a subtropical anticyclone extends from south america to south africa and the wave one asymmetry of the antarctic vortex is more pronounced and shifted eastward along with column ozone in september and en a strong anticyclone exists over south africa with a corresponding cold ozone poor anomaly in the stratosphere diminishing the western edge of the ozone maximum in october and ln a strong anticyclone exists over australia with an amplified trough on its poleward flank this trough is overlain by an ozone rich warm anomaly which expands the western edge of the ozone maximum and the polar vortex asymmetry is amplified and rotated westward

geological constraints on the precambrian history of earth s rotation and the moon s orbit over the past decade the analysis of sedimentary cyclic rhythmites of tidal origin i e stacked thin beds or laminae usually of sandstone siltstone and mudstone that display periodic variations in thickness reflecting a strong tidal influence on sedimentation has provided information on earth s paleorotation and the evolving lunar orbit for precambrian time before 540 ma depositional environments of tidal rhythmites range from estuarine to tidal delta with a wave protected distal ebb tidal delta setting being particularly favorable for the deposition and preservation of long detailed rhythmite records the potential sediment load of nearshore tidal currents and the effectiveness of the tide as an agent of sediment entrainment and deposition are related directly to tidal range or maximum tidal height and consequent current speed hence the thickness of successive laminae deposited by tidal currents can be a proxy tidal record with paleotidal and paleorotational values being determined by analysis of measured records of lamina and cycle thickness the validity of the findings can be investigated by testing the primary observed values for internal self consistency through application of the laws of celestial mechanics paleotidal and paleorotational values provided by late neoproterozoic 620 ma tidal rhythmites in south australia are validated by these tests and indicate 13 1 0 1 synodic lunar months yr 400 7 solar days yr a length of day of 21 9 0 4 h and a relative earth moon distance a a0 of 0 965 0 005 the mean rate of lunar recession since that time is 2 17 0 31 cm yr which is little more than half the present rate of lunar recession of 3 82 0 07 cm yr obtained by lunar laser ranging the late neoproterozoic data militate against significant overall change in earth s moment of inertia and radius at least since 620 ma cyclicity displayed by paleoproterozoic 2450 ma banded iron formation in western australia may record tidal influences on the discharge and or dispersal of submarine hydrothermal plumes and suggests 14 5 0 5 synodic months yr and a a0 0 906 0 029 the combined rhythmite data give a mean rate of lunar recession of 1 24 0 71 cm yr during most of the proterozoic 2450 620 ma suggesting that a close approach of the moon did not occur during earlier time concentrated study of precambrian tidal rhythmites promises to illuminate the evolving dynamics of the early earth moon system and may permit the lunar orbit to be traced back to near the time of the moon s origin

analysis of gravity waves generated at the top of a drainage flow abstract drainage or katabatic flows are common mesoscale circulations established as a result of differential radiative cooling of near surface air masses in sloping terrain the initial irruption of these flows with sudden shifts in wind speed and direction may result in vertical displacements of air parcels from their equilibrium position which prove to be a common source of internal gravity waves this paper illustrates this mechanism and describes the main features of the oscillations following the study of observational data gathered throughout one night during the stable atmospheric boundary layer experiment in spain 2006 sables2006 field campaign pressure differences measured by microbarometers set at different levels of a tower help to interpret the evolution of other atmospheric variables provide a detailed picture of the irruption of a drainage current and reveal the formation of gravity waves at its top the main parameters of the waves are derived from wavelet cross correlation of p

ftir microspectroscopy of ediacaran phosphatized microfossils from the doushantuo formation weng an south china abstract phosphatized microfossils from ca 580 ma from the doushantuo formation in the weng an region of south china were analyzed by fourier transform infrared ftir microspectroscopy for their chemical characterization two morpho types of phosphatized embryo like fossils megasphaera and megaclonophycus were analyzed together with algal fossils transmission ir spectra of the microfossils have absorption bands of around 2960 cm 1 and 2925 cm 1 indicating the presence of aliphatic hydrocarbon anti symmetric aliphatic ch 3 and aliphatic ch 2 and have an additional band of around 1595 cm 1 probably derived from aromatic moieties aromatic c c in addition ir microscopic mapping shows that aliphatic hydrocarbon and aromatics are distributed inside the embryo like fossils the embryo like fossils appear to show three types of ch 3 ch 2 peak height ratios r 3 2 and aromatic c c ch 2 peak height ratios r c c 2 values 1 high r 3 2 low r c c 2 type r 3 2 0 2 1 0 and r c c 2 0 2 2 low r 3 2 medium r c c 2 type r 3 2 0 2 0 6 and r c c 2 1 4 and 3 low r 3 2 high r c c 2 type r 3 2 0 2 0 6 and r c c 2 1 8 all three types are contained in both megasphaera and megaclonophycus raman spectra for the carbonaceous matter within the rock sample show a similar degree of thermal alteration indicating that the organics were embedded in situ prior to thermal maturation the ir spectroscopic differences might reflect differences in original organic compositions of microorganisms and or immediate post mortem alteration this suggests that the origins of phosphatized embryo like fossils are more diverse than was previously recognized on the basis of their morphology a comparison of r 3 2 and r c c 2 values in the embryo like fossils with those of the algal fossils and the extant microorganisms indicates the possible interpretation that some of the embryo like fossils belong to animal embryo others are algae but none of them originate from bacteria

500 mb winter variability over the antarctic palmer peninsula winter time variability of heights over the antarctic peninsula weddell sea and queen maud land are shown to have important contributions from correlations between the zonally averaged height field z and longitudinally asymmetric motions this is different from what it is observed at other longitudes where the time variance can be explained in terms of variance of the zonally averaged fields plus the variance of deviations from zonal averages it is shown that when z is larger than its winter average a pattern with southerlies over the weddell sea at 500 mb and northerlies over eastern antarctica develops south of 60 s these southerlies are found displaced about 15 northward with episodes of meridional wind magnitudes over eastern antarctica larger than 2 m s the equivalent barotropic structure of southern hemisphere tropospheric long waves justify extension of the 500 mb results presented here to higher levels recent measurements taken by the airborne antarctic ozone experiment in the upper troposphere and lower stratosphere 10 to 18 km above sea level have detected the presence of ozone depleted air over the antarctic peninsula and weddell sea it is conjectured here that this may be partly due to the transport of ozone poor air from high latitudes into this region

vertical displacements induced by quasi stationary waves in the southern hemisphere stratosphere during spring abstract vertical displacements induced by the quasi stationary wave with wavenumber 1 qsw1 in the southern hemisphere stratosphere during spring are studied the displacement exhibits two amplitude maxima located in the upper and lower stratosphere with a phase change of 180 between the two regions ozone mixing ratio and temperature wave signatures are explained by the wave induced displacement in the presence of mean vertical gradients the qsw1 induces radiative diabatic forcing in the upper stratosphere that results in a cross isentropic ozone transport correlation between vertical displacement at different levels and total ozone indicates that total ozone is directly connected to the displacement in the lower stratosphere the displacement extends to the tropopause and results in a correlation between total ozone and the tropopause height but with smaller values relative deviation between reconstructed potential vorticity pv by using a high resolution model and pv from observations indicates

a numerical study of strong katabatic winds over antarctica abstract certain coastal sections of antarctica most notably adelie land and terra nova bay experience anomalously intense persistent katabatic winds the forcing of such katabatic outflow is believed to originate several hundred kilometers upslope in the interior of the continent where cold air drainage currents from a large area converge into a relatively narrow zone focused on the steeply sloping ice terrain near the coastline numerical simulations with a three dimensional hydrostatic model incorporating terrain features representative of adelie land reveal a significant topographical channeling of the surface airflow katabatic wind speeds as depicted by the model are greatly enhanced downslope of the convergence channel these results emphasize the importance of topography in the continental interior in shaping the character of coastal katabatic flow

gcm simulations of the three dimensional propagation of stationary waves abstract plumb s formulation of the stationary wave activity flux is used to determine how well versions of the gfdl and ncar general circulation models simulate the sources sinks and horizontal propagation of atmospheric stationary waves which play an important role in determining regional climate the wave activity flux provides insight into the simulation of nondynamic as well as dynamic processes in these models model performances for current climate simulations are evaluated with respect to nmc analyses averaged over 1978 1990 the models fare best when the stationary wave forcing is strongest that is in the wintertime northern hemisphere where they reproduce the observed three branch structure of upward wave activity flux for the northern hemisphere summer and the southern hemisphere in both summer and winter the models show less agreement with observations although they do simulate the generally downward flux observed during northern hemisphere summer which the analysis suggests is cause

confined fluids in the earth s crust properties and processes abstract various processes in the earth s crust for which confined fluids have a controlling effect are discussed recent work which has led to a better understanding of the properties of confined fluids is highlighted we introduce the five papers in this special edition of chemical geology which represent current research trends in the study of confined fluids within the context of the geosciences

a numerical study of open water formation in sea ice 1 a multicategory sea ice model that explicitly takes into account redistribution of undeformed ice into categories of ridged and rafted ice is introduced with the intention of investigating the simulation of the open water fraction within sea ice the performance of this model is compared with that of a reduced model that accounts for only two categories the latter type of sea ice model being most widely used in global climate models two idealized scenarios are considered polynya formation along a coastline under offshore winds and a low pressure system passing over an ice field furthermore the two models are compared under more real world forcing conditions as they exist in the weddell sea in simplified situations both models produce identical results upon introduction of more realistic ambient conditions however the multicategory model produces larger open water fractions than the two level model concomitantly and consistently with earlier findings the multicategory model produces thicker ice this is a result of the larger horizontal gradients of ice motion which in turn are due to the weaker ice strength that arises from a higher abundance of thinner ice this leads to more open water as well as increased dynamical growth of ice the open water fraction is of relevance in global ocean circulation models where the amount of open water influences the deep and bottom water formation rates such as in conjunction with antarctic coastal polynyas

fourier transform infrared spectroscopy determinations of intragranular water content in quartz bearing rocks implications for hydrolytic weakening in the laboratory and within the earth abstract fourier transform infrared ftir spectroscopy has been used to measure intragranular water contents of quartz and feldspar within fine grained quartzites granite and naturally deformed mylonites calibrations and tests of methods developed for this application using natural and synthetic quartz standards indicate that hydrogen concentrations down to 30 ppm are detectable within apertured regions 100 200 m in diam and concentrations of 400 ppm measurable to an accuracy of 30 quartzite and novaculite starting materials used in previous studies of mechanical properties contain substantial intragranular water contents 2400 3900 ppm much larger than water concentrations commonly found in large clear natural crystals and more comparable to those of wet synthetic crystals however unlike molecular water within rapidly grown synthetic quartz most of this water is freezable resembling fluid inclusion water of natural milky quartz crystals likewise quartz and feldspar grains within granite and mylonites deformed at greenschist to upper amphibolite facies conditions contain large amounts of water from 500 to 8000 ppm as fine often submicron size fluid inclusions and ir spectra are dominated by a freezable o h absorption band comparisons between dry natural and wet synthetic quartz crystals have formed the basis for our understanding of hydrolytic weakening however mechanisms by which water related defects access dislocation cores within quartzites deformed in the laboratory and mylonites deformed within natural shear zones may differ from those within idealized natural and synthetic single crystals and their mechanical properties may not be directly comparable

quasi stationary waves in the southern hemisphere part i observational data abstract this part i presents selected major features of the quasi stationary monthly mean wave field in the troposphere and stratosphere of the southern hemisphere it is confirmed that the quasi stationary wave with zonal wavenumber 1 qs wave 1 is by far the dominant component of the geopotential height field at tropospheric and stratospheric levels the amplitude of this wave is largest at about 60 s all year round and reaches a maximum during september and october in the upper troposphere and stratosphere analysis of the elliasen palm flux vector suggests that at high latitudes the quasi stationary wave field is primarily forced from lower latitudes most prominently from the indian ocean region during june and october orographic and thermal forcing from antarctic regions seem to also be important sources of wave activity in polar and high latitudes particularly over southern south america and the atlantic ocean the contribution to the quasi stationary flow by the transient component of the fl

early tides response to varga et al abstract tidal cycling has been causally implicated at the origin of life but the speed of early tides has not been established the rotation period of the earth is the dominant parameter and a length of day lod of under 6 h at 3 9 ga was inferred by regression from present values lathe r 2004 icarus 168 18 22 however this would imply critical lunar proximity at that time in their commentary varga et al instead argue for a more distant moon proposing lod 16 8 h the debate is accentuated because regression from current values requires an earth moon juxtaposition at around 2 ga for which there is no evidence a smooth retreat from a moon forming impact at 4 5 ga is also irreconcilable with the weight of paleotidal evidence an inflection in the lunar recession curve is required to reconcile current and recent earth moon values with a 4 5 ga origin requiring a change in tidal friction during the evolution of the earth moon system depending on whether this took place at 2 2 5 ga before present or more recently 0 8 0 2 ga lod values are estimated at between 12 and 16 h suggesting a compromise figure of lod 14 h with tides every 7 h at 3 9 ga

the seasonal evolution of planetary waves in the southern hemisphere stratosphere and troposphere seasonality in planetary wave structure in the southern hemisphere stratosphere and troposphere 1000 1 mb is studied based on eight years 1979 1986 of daily geopotential data emphasis is placed on the distinctive seasonality in the stratosphere along with tracing the stratospheric fluctuations into the troposphere time filtering is used to separate stationary and transient components maximum geopotential height variance is observed in the middle to upper stratosphere in late winter spring with a distinct secondary smaller maximum in late fall early winter these maxima sandwich the strongest mid winter zonal winds this sequence occurs approximately one month earlier in the upper stratosphere two corresponding peaks are observed in stratospheric zonal mean wind and temperature fluctuations the two maxima in stratospheric wave variance are not in agreement with observed seasonal changes in quasi geostrophic refractive index of the zonal mean flow the stratospheric geopotential variance maxima result from nearly equal amounts of stationary and transient zonal wave 1 fluctuations with transient wave 2 also contributing during late winter stationary wave 1 shows intriguing seasonal evolution the early winter maximum is predominantly equivalent barotropic whereas that of late winter spring is highly baroclinic in the stratosphere stratospheric poleward fluxes of heat and momentum both exhibit pronounced maxima during september october these result primarily from the stationary wave 1 contributions and the transients assume a secondary role although not as pronounced as the stationary wave seasonality seasonal differences in transient wave behaviour are also documented including three dimensional propagation characteristics and wave mean flow interaction diagnostics

sensitivity of the brewer dobson circulation and polar vortex variability to parameterized nonorographic gravity wave drag in a high resolution atmospheric model abstractthe role of parametrized nonorographic gravity wave drag nogwd and its seasonal interaction with the resolved wave drag in the stratosphere has been extensively studied in low resolution coarser than 1 9 2 5 climate models but is comparatively unexplored in higher resolution models using the european centre for medium range weather forecasts integrated forecast system at 0 7 0 7 resolution the wave drivers of the brewer dobson circulation are diagnosed and the circulation sensitivity to the nogw launch flux is explored nogws are found to account for nearly 20 of the lowerstratospheric southern hemisphere sh polar cap downwelling and for less than 10 of the lower stratospheric tropical upwelling and northern hemisphere nh polar cap downwelling despite these relatively small numbers there are complex interactions between nogwd and resolved wave drag in both polar regions seasonal cycle analysis reveals a temporal offset in the resolved and parametrized wave interaction the n

intraseasonal variability of katabatic wind over east antarctica and planetary flow regime in the southern hemisphere the intraseasonal variation 30 to 50 day period of katabatic wind has been found at mizuho plateau east antarctica as a predominant mode of the subseasonal time scale variability the atmospheric circulation in the southern middle and polar latitudes associated with this fluctuation of katabatic wind has been deduced by using the nmc gridded 500 mbar zonal wind and geopotential height field the axisymmetric circulation pattern to antarctica is noticeable in the anomalous zonal wind and height field that is the strong weak katabatic wind phase corresponds to the shallower and broadened deepened and narrowed tropospheric circumpolar vortex with weaker stronger westerlies over the surrounding oceans these results strongly suggest that the intraseasonal variation of katabatic wind regime over east antarctica is part of the modulation of planetary flow regime and meridional circulation in the southern middle and high latitudes i e part of the index cycle of the southern hemisphere

carbonaceous biosignatures of diverse chemotrophic microbial communities from chert nodules of the ediacaran doushantuo formation the ediacaran doushantuo formation dst is renowned for exceptionally preserved precambrian fossils including metazoans some of these fossils particularly microfossils such as multicellular algae and acanthomorphic acritarchs are preserved in dst chert nodules to better understand the geomicrobiological processes that contributed to the authigenic formation of dst chert nodules and facilitated exceptional fossil preservation we analyzed organic matter in these chert nodules and the surrounding matrix calcareous mudstone using multiple in situ techniques confocal laser raman spectroscopy micro fourier transform infrared spectroscopy ftir and secondary ion mass spectroscopy sims we found strong ultrastructural chemical and isotopic heterogeneities in the organic matter as indicated by the raman spectral parameter i 1350 1600 ranging from 0 49 to 0 88 the infrared spectral index r3 2 from 0 12 to 0 90 and an estimated 13corg sims range of 44 v pdb these micron scale heterogeneities imply that the organic matter preserved in the dst chert nodules is derived from different carbonaceous sources in a diverse microbial ecosystem including eukaryotic and or prokaryotic photoautotrophs as well as chemotrophs involved in the fermentation and probably anaerobic oxidation of organic remains thus the microbial ecosystems in ediacaran ocean waters and sediments were more complex than previously thought and these microbial processes controlled dynamic micro environments in dst sediments where chert nodules were formed and fossils were mineralized the results also show that variations in the relative abundances activities and interactions of co existing microorganisms in dst sediments may have modulated 13corg shifts causing local decoupling between 13corg and 13ccarb as measured in bulk samples

secular effects of oceanic tidal dissipation on the moon s orbit and the earth s rotation the earth and moon are considered as a two body system in gravitational isolation from the sun and other planets the lunar orbit is taken as circular and the solid earth is assumed to be a rigid sphere with no tidal deformation so that there are no precessional torques other than those arising from the tidally deformed ocean numerical solutions to laplace s tidal equations with dissipation by linear bottom friction are used to obtain ocean wide distributions of tidal amplitude for two idealized continentalities a single circular continent spherical cap centered at the north pole and a single spherical cap centered on the equator calculations are made for two different values of the frictional resistance coefficient thus giving rise to four sets of solutions the computed tidal amplitudes are used to calculate the oceanic tidal torque which in turn is used to integrate the orbital equations backward in time for solution of the two body problem the coriolis parameter and the tidal frequencies change with time thus requiring that the tidal equations be solved several times during the course of each orbital integration in this manner the earth s rotational and the moon s orbital histories are determined on a geologic time scale for each of the four models the calculated position of the lunar orbit at 4 5 billion years ago is found to range from 38 to 53 earth radii in the four models and corresponds to a sidereal month of 330 to 550 hours the sidereal day would have been 12 to 18 hours with a relative inclination of 3 to 22 between the terrestrial and lunar poles these results are in sharp contrast to those from previous studies of the earth moon system most of which indicated a roche limit approach of the two bodies roughly 1 to 2 billion years ago and presented therefore a time scale difficulty in theories of lunar origin this contrast arises mainly from the fact that previous modelers avoided solution of laplace s tidal equations by prescribing a constant frictional phase lag angle between the angular position of the moon and the major axis of the second degree harmonic of the tidally deformed surface of the earth the amount of phase lag was established from the present astronomically deduced rate of tidal dissipation but this precluded dynamic variations in tidal torque over geologic time which are critical for determination of the orbital time scale the present rate of oceanic tidal dissipation is evidently anomalously high because of the near resonance of the oceanic response in both frequency and shape to the tidal forcing for the earth and moon to have evolved to their present separation from a distance of less than about 35 earth radii solely on the basis of oceanic tidal dissipation would have required the m2 response to have been near resonance for a significant portion of geologic history a rather implausible scenario the calculations reported here show that on the contrary frictional coupling between the earth and moon was much weaker than at present throughout most of the orbital history and consequently the moon s closest approach could not have been as small as 35 earth radii although idealized continentalities were used in these calculations the general conclusion of a weaker frictional coupling in the past is believed to be relatively insensitive to the continental configuration this is because at faster paleorotation the semidiurnal tidal frequencies would be resonant only with smaller scale normal modes of the ocean rather than with global scale modes as at present the time scale difficulty heretofore present in models of orbital evolution is thereby eliminated it should be noted that the orbital history developed here supports the theory of binary planetary accretion for lunar origin as opposed to fission or tidal capture

interaction of katabatic flow with local thermal effects in a coastal region of adelie land east antarctica katabatic flows largely dominate the climate of the adelie land coastal region a detailed climatological data analysis of dumont d urville has been conducted results of this study support the idea that katabatic flow can be locally enhanced by the diurnal cycle of solar insolation and the temperature contrast between the continent and the ocean the interaction between katabatic wind and local thermal effects is expressed in terms of scale analysis except for surface stress all terms in the momentum equation for a katabatic flow in a coastal region of antarctica can reach the same order of magnitude the local circulation then is the result of a relatively tenuous force balance which can be disrupted even by a weak perturbation of any term to estimate the effect of the temperature contrast between the ocean and the continent on the katabatic flow two numerical experiments have been conducted the simulations consider an ocean free of sea ice representative of the summer months and another winter case with the ocean covered by thick sea ice these simulations show that with the ocean free of sea ice the katabatic flows extend only a limited distance over the open ocean during the day due to the local thermal effects with the ocean covered by sea ice the katabatic winds are not constrained and extend a considerable distance offshore

horizontal energy propagation in a barotropic atmosphere with meridional and zonal structure abstract to investigate how the propagation of energy away from steady sources may be influenced by the horizontal structure of the time averaged flow in the troposphere solutions to a barotropic model are displayed and interpreted the model is steady and linearized about a basic state which varies in latitude and longitude emphasis is placed on cases where the longitudinal variations are gradual many of the results can be analyzed by locally applying tools developed for zonally symmetric basic states e g ray tracing and refractive indices simple background flows are constructed which have longitudinally confined critical lines reflective surfaces wave guides and regions conducive to propagation an example is given in which longitudinal derivatives of the basic state are significant the theory of ray tracing in a two dimensional wind must be employed as an interpretive tool in this case it is concluded that zonal variations tend to enhance poleward equatorward propagation in large scale tr

a diagnosis of rainfall over south america during the 1997 98 el nino event part ii roles of water vapor transport and stationary waves abstract a diagnosis of rainfall over south america sa during the 1997 98 el nino year is made examining the roles of water vapor transport and stationary waves it is found that the low level jet llj on the eastern side of the central andes is stronger during the el nino event and transports more moisture this seems to be the source for higher rainfall over southeast sa noted during the el nino years a calculation of three dimensional stationary wave activity fs for 1997 and 1998 showed that in the summer of 1996 97 stationary waves propagate poleward and eastward from midlatitudes into the higher latitudes to the west of south sa and then propagate equatorward to the east of sa during the autumn of 1997 the vertical component of fs is consistent with a blocking high over the southeast pacific to the east of this high cold air advection from antarctica occurs and to the west warm air advection occurs this is consistent with negative and positive centers seen in the vertical component of fs t

a natural example of crystal plastic deformation enhancing the incorporation of water into quartz abstract water content of quartz in and around a greenschist facies mylonitic shear zone located in the western adirondacks was analyzed by micro ftir spectroscopy the shear zone is within a pegmatitic dike which cuts across a granitic gneiss the thickness of the shear zone varies along strike from 15 cm wide and encompassing all of the pegmatite dike at its northern most exposure to 5 cm wide approximately 10 m south along strike microstructures including quartz ribbons and recrystallized grains indicate quartz and feldspar within the mylonite underwent dislocation creep infrared spectral analysis was carried out using a nicolet micro ftir on mylonitic quartz ribbons pegmatitic quartz and gneissic quartz a small aperture size 56 m by 50 m for the ir beam allowed optically clear regions of the quartz grains to be analyzed without any contribution from grain boundaries the smallest dimension of the quartz ribbons is 0 3 mm whereas the pegmatitic quartz has a grain size of 3 to 5 cm results show mylonitic quartz ribbons contain the most water 320 h 10 6 si average range of 50 to 1120 h 10 6 si pegmatite quartz contains much less water 30 h 10 6 si average range of 20 40 h 10 6 si and the gneissic quartz contained an intermediate amount 200 h 10 6 si average range of 20 to 870 h 10 6 si these data indicate that water was preferentially incorporated into the deformed quartz ribbons

intraseasonal variations in the southern hemisphere circulation abstract intraseasonal variations in the southern hemisphere atmospheric circulation have been examined through the application of a 10 50 day bandpass filter to daily ecmwf analyses for 1980 88 variations on this time scale contribute more than 40 of the daily variance in 500 hpa geopotential over much of the middle and high latitudes of the southern hemisphere eof analysis of the unnormalized variance for all seasons shows that 49 of this variance can be explained by zonal wave trains centered on the south pacific and southern atlantic indian oceans a high latitude mode of global extent and a wavenumber 3 pattern at midlatitudes these modes are essentially equivalent barotropic but slope westward with height so that the patterns at 100 hpa typically lag those at 1000 hpa by around 1o longitude there appears to be little interaction with the low latitude circulation all of the leading modes propagate eastward but the most consistent movement is shown by the south pacific wave train represented

glacier winds in the rongbuk valley north of mount everest 1 meteorological modeling with remote sensing data 1 persistent glacier winds blowing from noon to midnight in summer are present in the rongbuk valley north of mount everest with a maximum speed of 10 m s 1 and a vertical thickness as high as 1 km these glacier winds may bring upper level atmosphere ozone to the surface having a significant impact on the atmospheric environment such phenomena may be typical of the tibetan plateau where most high mountains are covered by snow or glacier ice throughout the year the advanced regional prediction model was used to simulate the down valley flows using realistic topography but neglecting synoptic winds the modeling results agree well with the observations obtained in june 2002 revealing that the glacier winds are thermal flows primarily driven by the along valley temperature gradient between the colder air over the glacier surface and the warmer air over surface areas covered by rock debris which maintains air advection along the rongbuk valley downslope winds over the glacier slopes especially from the western valley side and the west rongbuk glacier were forced by their inertia farther down into the valley and would intensify the glacier winds the narrowing of the rongbuk valley could also speed up the glacier winds sensitivity tests showed that the detailed distribution of the rongbuk glacier delineated by data from the enhanced thematic mapper plus on landsat 7 plays an important role in glacier winds development the glacier winds could be much weaker in winter when the area is completely snow covered

tidal friction in the earth moon system modern computers enable us to obtain realistic values for the present tidal torque between the moon and the oceans those values agree with the observations in principle computations for distant geological epochs are possible as well and have been performed however the very complex eigenperiod spectrum of the oceans today precludes a continuous reconstruction of the tidal torque for an essential part of the earth s history hence the original state of the earth moon system is still uncertain we emphasize the importance of results for intermediate timescales

precambrian length of day and the validity of tidal rhythmite paleotidal values paleotidal records obtained from sedimentary tidal rhythmites may be systematically abbreviated and so may give incorrect paleotidal and paleorotational values the validity of determined values including past length of day l o d can be assessed by testing for internal self consistency through application of the laws of celestial mechanics three independent values obtained from the 620 ma elatina reynella rhythmites in south australia 14 1 sidereal months year 401 sidereal days year and 19 5 years for the lunar nodal period when employed in different equations that make allowance for lunar and solar tidal effects each give a lunar semimajor axis in the range of 96 5 96 9 of the present figure such self consistency strongly supports the validity of the derived l o d of 21 9 hours at 620 ma the validity of the estimated l o d of 20 9 hours at 900 ma revised value big cottonwood rhythmites utah and of 17 1 18 9 hours at 2 5 ga weeli wolli rhythmites western australia cannot be assessed in that way because each data set has only one directly determined value the derived mean rate of lunar retreat of 2 16 cm year since 620 ma averts a close approach of the moon at least since 3 ga and a lower rate of retreat seems likely during the proterozoic

evolution in h 2 o contents during deformation of polycrystalline quartz an experimental study shear experiments were performed in a griggs type apparatus at 800 c and 1 5 gpa at a strain rate of 2 1 10 5s 1 using different starting materials i powder grain size 6 10 m of dry brazil quartz with 0 15 wt added h2o ii dry brazil quartz porphyroclasts grain size 100 200 m devoid of fluid inclusions embedded in the same fine grained powder and iii wet porphyroclasts grain size 100 200 m containing initially a high density of m scale fluid inclusions embedded in the same powder after hot pressing samples were deformed to large shear strains 3 to 4 5 in order for the microstructures and h2o distribution to approach some state of equilibrium the h2o content and speciation in quartz were analyzed by fourier transform infra red ftir spectroscopy before and after the experiments mechanical peak strength is generally lower in experiments with 100 hydrated matrix intermediate in experiments incorporating wet porphyroclasts with a proportion of 30 or 70 and highest in those with dry porphyroclasts all experiments with porphyroclasts show pronounced strain weakening and the strengths of most samples converge to similar values at large strain wet porphyroclasts are pervasively recrystallized during deformation while dry porphyroclasts recrystallize only at their rims and remain weakly deformed recrystallization of the initially fluid inclusion rich porphyroclasts results in a decrease in inclusion abundance and total h2o content while h2o content of initially dry clasts increases during deformation h2o contents of all high strain samples converge to similar values for matrix and recrystallized grains in samples with wet porphyroclasts shear bands with high porosity and fluid contents develop and they host the precipitation of euhedral quartz crystals surrounded by a free fluid phase these high porosity sites are sinks for collecting h2o in excess of the storage capacity of the grain boundary network of the recrystallized aggregate the h2o storage capacity of the grain boundary network is determined as a h2o boundary film of 0 7 nm thickness

spectroscopic ftir imaging of water species in silicic volcanic glasses and melt inclusions an example from the izu bonin arc recent advances in ftir spectroscopic imaging allow images of elements or molecules such as water to be constructed on samples over a large sub mm area the imaging detector consists of 64 64 channels providing 4096 individual spectra simultaneously collected over a spectral range of 4000 900 cm 1 the wavelength range includes measurable peaks for water and carbon species making it ideal for the analysis of volcanic glasses particularly melt inclusions advantages of spectroscopic imaging include high spatial resolution 5 m allowing the analysis of melt inclusions too small to be analysed by other micro ftir techniques and the acquisition of high definition in situ images of the materials analysed the technique is applied to the analysis of water species concentrations and distribution in silicic volcanic glasses from sumisu caldera and torishima volcano in the izu bonin arc to test the application of imaging to geologic samples results obtained are found to be comparable to analyses by conventional micro ftir techniques withsimilarprecision butgreaterspatialresolution groundmassglassesfromsumisucalderadacitescontain1 2 1 4wt h2o and an obsidian sample from torishima volcano contains 0 2 wt h2o consistent with water saturation at their respective pressures of eruption melt inclusions in honeycomb plagioclase from sumisu caldera have higher water contents 1 02 1 38 wt h2o than inclusions from torishima volcano plagioclase 0 22 0 41 wt h2o despite evidence for many inclusions being trapped wholly within honeycomb plagioclase low water contents similar to those of the groundmass glasses suggest that the inclusions underwentwaterlossbydegassingand or diffusion alternatively iflowwatercontents ofthemeltinclusionsreflectthecompositionof the magma at the time of entrapment then the magma can be constrained as having originated from a water poor source despite the ambiguity in initial water contents of the magma the anhydrous mineral assemblage of all sumisu caldera and torishima silicic rocks indicates anoriginfrom awater poorsource consistent withmodelsfor partialmeltingofwater poor mafic lower mid crust ratherthan melting of wet lower mid crust or differentiation from basaltic magmas

effect of air sea ice interaction on winter 1996 southern ocean subpolar storm distribution air sea ice interaction processes in the southern ocean are investigated utilizing space observed surface winds sea ice concentration and sea surface temperature sst from september through december 1996 the sea ice edge sie shows three ice extent maxima around the antarctic during september and october when sea ice coverage is maximum they are located in the central indian ocean east of the ross sea and in the eastern weddell gyre during september and october most of the strong and long lasting storms initiate northeast of the three sea ice maxima such spatial distributions of storms and sea ice reflect coupling processes of the air sea ice interaction a relatively stable wave number 3 atmospheric circulation pattern that is believed to be fixed by the land ocean distribution prevails during the ice maximum season the ice extent maxima coincide with strong southerlies and divergent wind fields associated with this pattern which suggests that the mean atmospheric circulation determines the ice distribution the ice extent maxima can enhance the regional meridional surface pressure gradient and therefore strengthen the westerly winds north of the ice edge the decreasing ice extent east of the ice maxima creates a local zonal thermal gradient which enhances local southerlies this positive feedback between the wave pattern in the mean atmospheric circulation and ice distribution partially causes the eastward propagation of the ice maxima and also provides a favorable condition for cyclogenesis northeast of the ice extent maxima the mechanism of the cyclogenesis is the baroclinic instability caused by the cold air blown from the ice pack to the warm open ocean waters where the sst is warmest off the sie and the southerlies are the strongest the potential for cyclogenesis is most likely this is consistent with the observations

lagrangian study of the final warming in the southern stratosphere during 2002 part ii 3d structure this two part paper aims to provide a lagrangian perspective of the final southern warming in spring of 2002 during which the stratospheric polar vortex spv experienced a unique splitting we approach the subject from a dynamical systems viewpoint and search for lagrangian coherent structures using a lagrangian descriptor that is applied to reanalysis data part i presents our methodology and focuses by means of a kinematic model on the understanding of fundamental processes for filamentation and ultimately for vortex splitting on an isentropic surface in the middle stratosphere the present part ii discusses the three dimensional evolution of the flow during the selected event for this we apply the definition of vortex boundary developed in part i for guidance in the selection of trajectories to illuminate the evolving flow structures and invoke a criterion that allows to justify why at an isentropic level a pinched vortex will split in later times lagrangian structures identified include surfaces that are several kilometers deep and which a particle trajectory analysis confirms as barriers to the flow the role of lagrangian structures in determining the fate of particles during the spv splitting is discussed

characteristics of the ross ice shelf air stream as depicted in antarctic mesoscale prediction system simulations 1 streamlines of the mean annual near surface winds over the antarctic continent suggest a confluent channeling of the drainage flows off the ice sheets and onto the ross ice shelf a persistent cyclonic circulation to the north of the ice shelf supports a large scale pressure field that reinforces the continental drainage flows owing to these two processes an enhanced low level airflow is present along the southern and western sections of the ross ice shelf the resulting air stream known as the ross ice shelf air stream ras is one of the persistent and prominent low level wind features seen in the antarctic real time mesoscale simulations of the antarctic atmosphere and high southern latitudes using a modified version of the pennsylvania state university national center for atmospheric research mesoscale modeling system have been ongoing since the 1999 2000 austral field season model results from the 1 year period november 2001 to october 2002 have been analyzed to investigate the mean structure and modulation of the ross ice shelf air stream analyses of model results show the low level air stream over the western ross ice shelf has a wind speed maxima that is linked to the steep topography to the west individual cases of strong wind events appear to contain a significant barrier wind component that arises from cold air damming against the transantarctic mountains cyclones that frequently form in the ross sea are shown to establish conditions that promote barrier wind dynamics and thus significantly modulate the intensity of the ras

diagnosis of the katabatic wind influence on the wintertime antarctic surface wind field from numerical simulations abstract katabatic winds have long been recognized as one of the key climatic variables of the low level antarctic environment antarctic surface winds display a high degree of persistence with mean directions related to the local topographic configuration of the ice sheet consistent with katabatic forcing continental orography also constrains the atmospheric boundary layer motions through blocking and cold air damming finally the coastal rim about the antarctic continent is among the most active baroclinic zones on earth the establishment of the low level wind field over antarctica is thus potentially the result of a number of interacting processes to quantify the forcing of the wintertime surface wind field over the antarctic continent two numerical strategies are presented first idealized numerical simulations are conducted to illustrate the strong orographic control of the low level wind field second a series of daily numerical simulations using the fifth generation pennsylvania state unive

influence of tropical convection on the southern hemisphere ozone maximum during the winter to spring transition 1 during the southern hemisphere sh winter a zonally asymmetric maximum in column ozone develops south of australia which amplifies from august through october this ozone maximum lies in the band 50 60 s and extends from the southern indian ocean to the eastern pacific it is proposed that the location of the ozone maximum is due to the geographical distribution of outflow from tropical convection in the upper troposphere and lower stratosphere utls which is concentrated over the southern indian ocean this southward flow of tropical air creates subtropical anticyclones in the utls and provides the angular momentum for the entrance to the australian westerly jet the ozone rich troughs in synoptic waves breaking on the jet contribute to the monthly mean ozone maximum poleward of the jet as indonesian convection contracts zonally and shifts eastward during sh spring so do the australian jet and ozone maximum in addition extratropical planetary waves become more active from august through october convective outflow surges lead to amplification of subtropical anticyclones which often extend into the lower stratosphere and merge with stalling planetary wave ridges amplification of these ozone rich ridges over the high latitude south pacific contributes to the eastward shift of the ozone maximum the utls over the southern indian ocean appears to be a sensitive region where tropical convection can influence extratropical planetary waves via excitation of subtropical anticyclones and propagation of rossby wave activity through the connecting westerly waveguide

dislocation creep of dry quartz small scale shear zones within the permian truzzo meta granite developed during the alpine orogeny at amphibolite facies conditions in these shear zones magmatic quartz deformed by dislocation creep and recrystallized dynamically by grain boundary migration with minor subgrain rotation recrystallization to a grain size of around 250 750 m consistent with flow at low differential stresses fourier transform infrared ftir spectroscopy reveals very low water contents in the interior of recrystallized grains in the form of discrete oh peaks 20 h 10 6 si and very little broad band absorption 100 h 10 6 si the spectral characteristics are comparable to those of dry brazil quartz in ftir spectra magmatic quartz grains show a broad absorption band related with high water concentrations only in those areas where fluid inclusions are present while other areas are dry drainage of fluid inclusions and synkinematic growth of hydrous minerals indicates that a hydrous fluid has been available during deformation loss of intragranular water during grain boundary migration recrystallization did not result in a microstructure indicative of hardening these ftir measurements provide the first evidence that quartz with extremely low intragranular water contents can deform in nature by dislocation creep at low differential stresses low intragranular water contents in naturally deformed quartz may not be necessarily indicative of a high strength and the results are contrary to implications taken from deformation experiments where very high water contents are required to allow dislocation creep in quartz it is suggested that dislocation creep of quartz in the truzzo meta granite is possible to occur at low differential stresses because sufficient amounts of intergranular water ensure a high recovery rate by grain boundary migration while the absence of significant amounts of intragranular water is not crucial at natural conditions

the dynamics of idealized katabatic flow over a moderate slope and ice shelf summary a non hydrostatic numerical weather prediction model has been employed to simulate idealized katabatic flows over a moderate slope and adjoining ice shelf the topography of coats land and the adjoining brunt ice shelf antarctica has been used this is typical of much of the antarctic coastline the regional atmospheric modeling system version 4 3 has been adapted for simulations over compacted snow most notably through changes to the multi layer soil model the simulations are initialized using clear sky conditions and at rest on the slope a shallow katabatic flow develops the winds becoming approximately steady on the slope by 12 h the peak downslope winds are about 7 m s 1 at 30 m above the snow surface the katabatic flow depth ranges from 50 to 100 m down the slope over the ice shelf the katabatic flow peters out while a pool of cold air develops primarily through sensible heat loss into the surface and partially balancing the net radiative heat loss to space near surface and sounding data from the model simulations compare well with archetypal and typical katabatic flow observations especially after some tuning of the model s turbulence parametrization an analysis of the downslope flow dynamics shows the buoyancy force is generally balanced by the inertial force except towards the foot of the slope where it is balanced by upslope forces related to gradients in the potential temperature deficit and katabatic layer height caused by the pool of cold air over the ice shelf over time the cooling of the ice shelf boundary layer leads to an apparent retreat of the katabatic flow from the ice shelf and some way up the slope the dynamical analysis explains the surface climatology observed such that the persistent katabatic winds of coats land rarely reach the brunt ice shelf the simulated katabatic flow moves from shooting to tranquil towards the foot of the slope this transition acts to trigger a train of internal gravity waves which propagate energy upwards away from the katabatic flow jump previous studies have also found shooting to tranquil katabatic flow transitions so to generalize these findings would suggest that internal gravitywave generation is ubiquitous around much of coastal antarctica and greenland

the role of eolian processes in forming surface features of the martian polar layered deposits abstract the major topographic features of the martian polar layered deposits include the conspicuous spiral troughs subtle undulations broad reentrants chasma steep arcuate scarps and dune fields a prominent role for eolian processes in the formation of all of these features is proposed strong katabatic winds occur on the north polar cap producing widespread frost streaks these cold drainage winds are analogous to those on the terrestrial antarctic cap in the chasmae convergent katabatic winds create yardangs and erode arcuate scarps in the layered deposits that are also the source for local dune fields migrating outward from the polar cap the chasmae are postulated to originate by long term erosion by katabatic wind wind plays a role in formation of the troughs and scarps primarily through removal of dust freed from exposed layered deposits by ablation of ice on defrosted equator facing slopes the undulations are created by interaction between surface erosion or deposition of perennial ice and standing waves in the shallow katabatic windflow the south polar layered deposits exhibit topographic features similar to those at the north polar cap but erosion and depositional processes creating these features may be inactive during the current epoch because of the lack of an extensive perennial ice cover and associated katabatic wind

climatic atmospheric outflow at the rim of the antarctic continent using gauss s divergence theorem we examine the role of the net radiative cooling and of the entrainment of potentially warm air from the free atmosphere into the surface layer in determining the intensity of the cold air outflow at the rim of the antarctic continent the result shows that a large amount of cold air significant at even a global climatological scale is exported through this process from high to low latitude regions the theory gives also the average intensity of the wind at the coast in the coastal regions of antarctica the wind exhibits a complex behavior observations show that katabatic winds in the near coastal region can be periodic or continuous or can stay a long time in a quiescent near critical state then burst in short and strong gusts we examine some aspects of these katabatic winds in terms of the mesoscale energy theory developed by dalu and green 1983 this complex behavior is described by a nonlinear system where the relevant parameter is the froude number of the inflow at a rossby radius distance from the coast the analytical theory developed agrees well with qualitative features observed

the effect of reflecting surfaces on the vertical structure and variability of stratospheric planetary waves the effects of an upper stratospheric reflecting surface on the vertical structure of stratospheric planetary waves are considered a diagnostic of the basic state wave propagation characteristics which is particularly useful for determining the existence and location of turning surfaces for meridional and vertical propagation is developed the diagnostic used is a more accurate indicator of wave propagation regions than the index of refraction because it diagnoses meridional and vertical propagation separately the diagnostic is tested on a series of simple models both steady state and time dependent it is found that the stratospheric waveguide sets the meridional wavenumber of the waves regardless of the characteristics of their tropospheric forcing making it easier to understand the effects of damping and turning surfaces on the vertical structure of the waves the diagnostic is then applied to observations of the southern hemisphere winter of 1996 it is shown that the differences in vertical wave structure between middle and late winter can be explained as a linear response to the seasonal evolution of the basic state which involves a formation of a reflecting surface in late winter it is also shown that on daily timescales wave mean flow interactions cause significant changes in the basic state propagation characteristics for periods of a few days these changes along with the time variations in the forcing of the waves are responsible for the observed daily timescale variations in wave structure the fact that the observed evolution of the waves and the basic state are consistent with linear or quasi linear wave theory depending on the timescale looked at supports the applicability of the theory as well as the validity of the observations

calculating earth moon system parameters from sub yearly tidal deposit records an example from the carboniferous tradewater formation abstract the secular evolution of the earth moon system remains poorly constrained largely because there are few continuous tidal rhythmite or foreset bundle sequences that preserve deposition over more than several neap spring tidal cycles deposits recording less than one year of deposition do not facilitate direct calculation of past lunar distance directly from kepler s laws but may prove necessary to reconstruct lunar orbital evolution because they are far more common than longer records a method is demonstrated to make use of shorter tidal deposit sequences by utilizing conservation of angular momentum between the earth and moon and estimating the solar component of tidal deposition while assuming a constant moment of inertia for earth since the proterozoic the precision and accuracy of spectral estimates obtained from short records are considered as are the limitations of subsequent calculations of earth moon parameters the late carboniferous abbott sandstone of the tradewater formation in the illinois basin preserves just over 6 apparently continuous neap spring cycles in its semidiurnal deposits the quality of these data as assessed via sedimentological evidence and statistical time series properties produces spectral estimates that are likely within at least 5 of the actual underlying periodicity 90 accuracy to test the usefulness of such records we assessed the possible scenarios of 90 and 95 accuracy at 90 accuracy the error bounds on earth moon parameter estimates become rather large and render individual data sets to be of limited use at 95 accuracy very general inferences about the evolution of the earth moon system may be made calculated mean lunar orbital distance at 315 ma is 3 798 10 8 m with error bounds of 0 086 10 8 m and 0 046 10 8 m we conclude that short sequences of cyclic tidal deposits offer rather limited resolution of lunar distance estimates utilizing multiple sub yearly data of similar age in ensemble may prove necessary if further investigations of secular changes in earth moon parameters are to proceed

surface winds over the antarctic continent a review surface winds over antarctica often classified as katabatic are intimately related to the orientation and steepness of the underlying ice terrain such flows result primarily from the strong radiational cooling of the sloping ice surface which creates a downslope directed horizontal pressure gradient force it is possible to diagnose the time averaged near surface streamline patterns of cold air drainage currents using recently compiled detailed antarctic ice topography maps and appropriate estimates of the strength of the surface temperature inversion the resulting streamlines agree with available observations and illustrate the high degree of nonuniformity of gravity driven flows off the ice sheets in certain interior sections negatively buoyant air from a large catchment area drains through a restricted section of coastline such confluence zones represent regions of enhanced supplies of cold air and are shown to be related to anomalously strong katabatic winds implications for sea ice formation are discussed

recent large scale changes in the extratropical southern hemisphere atmospheric circulation abstract the zonal anomalies in the 500 hpa geopotential height field of the southern hemisphere are examined using the national centers for environmental prediction national center for atmospheric research reanalyses 1958 96 the zonal anomalies were constructed by removing the zonal mean from each grid point and principal components analysis was performed on the resulting spatial anomalies the principal components of the leading eof of the seasons march april may mam to september october november son indicate that a change has occurred in the extratropical large scale atmospheric circulation of the southern hemisphere it is estimated to have begun after 1975 and is limited to the southern late fall winter and early spring the elements of this change are a deeper pacific trough and higher indian ocean ridge at subtropical latitudes at higher latitudes the ridge over the pacific strengthened and shifted east while troughing occurred in the southwest atlantic weddell sea region consistent wi

variations in water content in opal a and opal ct from geyser discharge aprons abstract opal a sio2 nh2o and its diagenetic derivative opal ct are found in environments that range from the deep ocean floor to terrestrial spring geyser systems although the loss of water may be a critical factor in the transition from opal a to opal ct analytical difficulties in determining the distributions and quantities of molecular water h2omol and silanols h2osioh has hindered a full understanding of the processes involved with this diagenetic transition electron microprobe emp and micro fourier transform infrared ftir analyses of opal a and opal ct collected from geyser discharge aprons on iceland and the north island of new zealand produce compatible and reliable derivations of the total weight water in opal a and opal ct provided that they contain 1 wt of other elements such as al emp analyses produce excellent results where microscale variations in total water content are required but it cannot determine if that water is formed of molecular water h2omol or silanols h2osioh in contrast ftir analyses yield total water molecular water and silanol contents of the opal microscale variations however are commonly masked because the scale of ftir analysis is coarser than that for emp analyses analyses of sinters from iceland and new zealand show that the opal a contains 2 1 12 1 average 7 3 wt total water whereas the opal ct contains 1 0 8 9 average 5 5 wt total water based on ftir analyses the opal a contains 1 2 9 8 average 6 8 wt molecular water and 0 4 2 4 average 1 0 wt silanols compared to opal ct which contains 3 8 8 2 average 6 7 wt molecular water and 0 1 0 7 average 0 2 wt silanols the dual usage of emp and ftir analyses provide important information on the distribution of different types of water in opal a and opal ct irrespective of the environments where they formed

midwinter warmings in the southern hemisphere stratosphere in 1988 an analysis was made of intense midwinter warmings which took place in the southern hemisphere stratosphere during august september 1988 by using the southern hemispheric data set up to the 1 mb level provided by the japan meteorological agency it is found that the 30mb temperature increase over eastern antarctica about 60 k for 10 days from 22 august to 1 september is associated with the amplification of a quasi stationary planetary wave of zonal wavenumber 1 the enhancement of wave 1 appears quasi periodically with a period of about 2 weeks during the midwinter of 1988 clear evidence is presented to show that the quasi periodic amplification of wave 1 is due to the wave wave interaction between the quasi stationary forced wave of wavenumber 1 and the eastward travelling wave of wavenumber 2 it is emphasized therefore that the mechanism of warming in this case is quite different from that of the transient vertical propagation of a planetary wave forced from below as observed in the northern hemisphere winter

a sudden warming in the middle atmosphere of the southern hemisphere this paper presents a case study of a wave mean flow interaction or minor warming near the southern hemisphere stratopause for 15 30 july 1974 the analysis is based mainly on data from the selective chopper radiometer carried by nimbus 5 a deceleration of the zonal mean wind of 70 m s 1 from 20 to 25 july is observed in middle latitudes at 0 5 mb with an acceleration further south the polar vortex is however not disrupted eliassen palm cross sections are presented for the event and a good correlation found between the e p flux convergence and the deceleration the channelling of the e p fluxes from the tropopause to the convergent region is in broad agreement with the distribution of refractive index but there is a region of e p flux divergence at high levels in polar latitudes suggesting a source of wave activity there the residual circulation is calculated both from the momentum budget and from an omega equation both methods diagnosing a region of modest equatorward flow near the region of e p flux divergence embedded in the stronger poleward flow elsewhere maps of potential vorticity on the isentropic surface of 0 1640 k are presented and the evolving pattern related to zonal mean and isobaric descriptions the event is shown to be associated with an incursion of low latitude air into middle latitudes with a corresponding irreversible mixing of potential vorticity reminiscent of the wave breaking in northern hemisphere events reported by mcintyre and palmer j at ter ph 46 825 but of much smaller amplitude