memorial of benjamin f leonard iii 1921 2008 benjamin franklin leonard iii at age 87 passed away peacefully at his home in mccall idaho on september 5 2008 ben had a long and distinguished career at the u s geological survey where he established himself as an accomplished field geologist and an internationally recognized expert in ore microscopy born in dobbs ferry new york on may 12 1921 ben spent much of his early life in the eastern united states graduating from hamilton college in 1942 b s a salutatorian and member of phi beta kappa and then princeton university in 1946 m a and 1951 ph d where he was a member of sigma xi ben s geologic career began as a field assistant to allen heyl in the summer of 1942 for the geological survey of newfoundland mapping igneous and metamorphic rocks and magnetite deposits his u s geological survey career began as a field assistant in 1943 to a f buddington doing regional geologic mapping and studying magnetite deposits in new york for which he mapped about 1000 square miles of the st lawrence county magnetite district in the northwest adirondacks and pennsylvania and copper deposits in new jersey and pennsylvania while still a graduate student at princeton university his graduate studies on the ore deposits in the st lawrence county magnetite district culminated in his doctoral dissertation later published by the u s geological survey as professional paper 377 considered to be the major treatise on the district his transition to the western u s started ca 1951 when he and his wife eleanor vandy moved to golden colorado and ben became a member of the minerals branch at the u s geological survey in lakewood with his ph d fresh in hand he began full time work on survey projects including continued research in the st lawrence county magnetite district ben s field research soon expanded

the ordovician chondrite from brunflo central sweden ii secondary minerals abstract brunflo is an altered h4 h5 stony meteorite that fell in calcareous mud on the continental shelf of the iapetus ocean about 460 470 ma b p except for relicts of chromite all the original minerals are replaced by calcite barite an illite type mineral and some minor to rare phases carbonate fluorapatite quartz titanium dioxide chalcopyrite three different members of the cobaltite gersdorffite series including a phase with a composition close to coni ass 2 rammelsbergite safflorite nickeline maucherite orcelite native nickel anomalous bornite galena pyrite sphalerite and two cu phases cu1 66s and cu4fes4 the secondary mineralogy varies rapidly at a mm scale indicating non equilibrium conditions during the alteration by the time the mud was cemented to limestone most of the original minerals might have been transformed to secondary phases during subsequent stages of diagenesis the temperature remained within the 0 50 c range for millions of years probably explaining the formation of the phases of unusual compositions a temperature rise to 200 300 c chiefly due to regional heating during the caledonian orogeny in silurian devonian time might have modified the secondary mineralogy

on the stochastic theory of solute transport by unsteady and steady groundwater flow in heterogeneous aquifers abstract in this study the exact and approximate deterministic partial differential equations of the time space evolution of mean solute concentration of solute concentration two point moment and of solute concentration n point moment for conservative solute transport by unsteady and steady groundwater flow in a heterogeneous aquifer were developed in the real time space domain under second order cumulant expansion these derivations were performed by means of the cumulant expansion method combined with the calculus for the time ordered exponential and with the calculus for lie operator the mean solute transport equations which describe the time space evolution of mean conservative solute concentration under transport by unsteady and steady groundwater flows in a heterogeneous aquifer have convective dispersive forms whose convective and dispersive coefficients are defined precisely in terms of the mean and covariance functions of the pore flow velocity random field however owing to the spatial nonuniformity of groundwater flow in heterogeneous porous media a new convective coefficient besides the standard mean velocity vector appeared in the derived mean solute transport equations in the case of steady flows in the case of transport by unsteady groundwater flow in a heterogeneous aquifer the new convective coefficient besides the standard mean velocity vector is due to the non zero divergence of the pore flow velocity the fundamental reason for the convective dispersive form of the mean transport equations is the second order truncation of the formal cumulant expansion in the derived mean solute transport equations the macroscopic dispersion coefficient emerges as the time integral of the covariance function of the pore flow velocity however both in the case of transport by unsteady groundwater flow and in the case of transport by steady spatially nonstationary nonuniform groundwater flow the macroscopic dispersion coefficients and convective coefficients vary with spatial locations within the porous medium only in the case of transport by steady spatially stationary nonuniform flow are both the macroscopic dispersion coefficient and the convective coefficient constant with respect to spatial location within the heterogenous aquifer therefore only in the case of conservative solute transport by steady spatially stationary nonuniform groundwater flow in a heterogeneous aquifer does the mean transport equation apply to all spatial locations within the aquifer with the same parameter values at each time instant

the cr renazzo type carbonaceous chondrite group and its implications abstract a petrologic geochemical and oxygen isotopic study of eight meteorites identified as cr renazzo type chondrites reveals that they have a set of similar properties that distinguishes them from other chondrite groups and confirms cr as a carbonaceous chondrite group characteristics of the cr group include 1 1 abundant large multilayered fe ni metal rich type i chondrules 2 2 abundant matrix and dark inclusions di that contain microchondrules microfragments and magnetite framboids and platelets 3 3 unique assemblages of serpentine and chlorite rich phyllosilicates and ca carbonates 4 4 ca carbonate rims on chondrules 5 5 abundant fe ni metal with a positive ni vs co trend and a solar ni co ratio 6 6 low abundance of refractory rich inclusions 7 7 amoeboid olivine aggregates aoa with mn rich and mn poor forsterite and 8 8 oxygen isotopic compositions that form a unique mixing line the cr chondrites are breccias consisting of two major components the large layered chondrules and the matrix dark inclusions al rais is an anomalous member in having a higher abundance of the dark inclusion component 70 vol and this accounts for its having a higher volatile content than other members of the group the conditions that prevailed during aqueous alteration of the cr chondrites differed from those of other hydrated chondrite groups and may be the result of a higher temperature environment than that for the ci and cm chondrites the cr chondrite components chondrules matrix dark inclusions etc experienced aqueous alteration to differing degrees prior to assembly of the host chondrites and dark inclusions represent a lithology that was altered by water to a greater degree than the rest of the meteorite the overall degree of hydration in cr chondrites varies among meteorites with al rais being the most hydrated the oxygen isotopic variation of the whole rocks chondrules and matrices may be related to degree of hydration indicating that cr chondrites interacted with a water rich component having heavy oxygen and that was the same as ci and cm water

compositions of large metal nodules in mesosiderites links to iron meteorite group iiiab and the origin of mesosiderite subgroups large mesosiderite metal nodules were studied petrographically and by neutron activation their large sizes minimized the effects of silicate contamination and dilution by fe reduced from feo the remarkable mixture of subequal amounts of metal and basaltic and pyroxenitic silicates in mesosiderites can be explained by the accretion of a core like metal mass from one asteroid onto the surface of another asteroid our data show that the accreted mass had a composition roughly similar to that of the iiiab iron meteorite core consistent with other evidence of close genetic links between these and other related groups the siderophile compositional pattern the very limited compositional range the inferred large projectile target ratio and the electrical interconnectedness of mesosiderite metal indicate that the bulk of the metal was molten when accreted mesosiderites have been divided into plagioclase and tridymiterich subgroup a and orthopyroxene rich subgroup b on the basis of modal silicate mineralogy roughly the same subgroups are defined by metal compositions au as ni and cu are generally higher and w lower in subgroup a than in subgroup b in our sample set a widmanstatten pattern is only observed in nodules from subgroup a a plausible model is that subgroup a best preserves the compositions of the target regolithic silicates and accreted core subgroup b is comprised of these materials together with a minor amount of coremantle materials consisting of olivine and refractory ni poor metal the independent covariation of ga re and ir may in part reflect fractionations during impact heating events the anomalous mesosiderite reckling peak a79015 is strongly depleted in refractory siderophiles and slightly enriched in volatile siderophiles such evolved metal requires a formation distinct from common mesosiderite metal

the boundary layer winds in hurricanes danielle 1998 and isabel 2003 abstract this paper describes the boundary layer wind structure and dynamics of hurricanes danielle 1998 and isabel 2003 based on the analysis of high resolution global positioning system dropwindsonde data and simulation of the flow by a three dimensional boundary layer model produced by kepert and wang the observations show that the hurricane boundary layer has a complex three dimensional structure with large variability over small distances the analysis emphasizes three aspects the degree of gradient wind balance the radially varying depth of the boundary layer and the strength of the near surface wind speed relative to that at a higher level each aspect is compared both with results obtained in a simulation of the individual storm by kepert and wang s model and with theoretical predictions the observations show that the boundary layer depth decreases toward the center of the storm consistent with theoretical arguments the strongest azimuthal winds occur near the top of but still within

geochemistry of meteorite rich marine limestone strata and fossil meteorites from the lower ordovician at kinnekulle sweden abstract thirteen fossil meteorites 1 5 9 cm have been found in lower ordovician orthoceratite limestone at kinnekulle sweden the meteorites were recovered from a 3 5 m thick quarried interval in the middle of a 30 m thick section of orthoceratite limestone the section formed in an epicontinental sea at very slow sedimentation rates 0 2 cm ka the limestones of the lower two thirds of the section are reddish brown except in the quarried interval where a conspicuous 1 m thick grey limestone bed occurs ten of the meteorites were found in a thin bed below the grey limestone one was found in the grey limestone and two in the red limestone above the meteorites are almost completely pseudomorphosed primarily by calcite and barite they were identified by their content of chromite grains and chondrule pseudomorphs the central part of one of the meteorites shows iridium 800 ppb gold 550 ppb and chromium 4400 ppm concentrations in typical chondritic abundances centimeter resolution profiles for iridium and eight other elements have been established through the quarried interval at a site at 4 km distant from the meteorite producing quarry in the reddish brown parts ir concentrations carbonate free basis lie typically in the range 300 400 ppt compared with 50 ppt ir in average shale in the grey limestone the ir concentrations are lower around 100 150 ppt iridium correlates with iron and appears to be related to sedimentation rate and or iron redox state rather than to any variations in the composition of the siliciclastic fraction with estimated sedimentation rates as above the excess ir flux to the sediment was 30 ng cm 2 ma which is a factor 2 3 higher than the present total ir flux and one order of magnitude higher than the extraterrestrial ir flux to the pacific sea floor our data cannot discriminate to what extent the ordovician ir enrichments are related to extraterrestrial matter or to precipitation of ir from seawater in recent deep sea sediments seawater derived ir enrichments are associated with mn oxides but no similar association occurs in the orthoceratite limestone the ten meteorites in the bed below the grey limestone reflect minimum meteorite accumulation rates of one meteorite per 150 m 2 and 175 ka probably the ten meteorites are related to a local strewn field rather than to background influx minimum accumulation rates calculated on three meteorite finds 20 g in the entire quarried interval give one meteorite per 570 m 2 and 1 17 ma which is one order of magnitude higher than present day large area averaged meteorite influx rates the probability is low that the small area 2 of the sea floor studied would happen to be one where an unusually high number of meteorites struck our results may reflect that meteorite and possibly also extraterrestrial ir influx rates were substantially higher than at the present during a period in the early ordovician enhanced influx rates could be related to an asteroid collision in space

eastern pacific hurricanes jimena of 1991 and olivia of 1994 the effect of vertical shear on structure and intensity abstract shear is a key inhibitor of tropical cyclone intensification although its signature is readily recognized in satellite imagery and theoretical or modeling studies provide some insight detailed observations have been limited airborne radar and in situ observations in hurricanes jimena of 1991 and olivia of 1994 are a step toward better understanding each storm was observed on two consecutive days initially both had small eyes 16 18 km radius and maximum winds of 57 m s 1 over sea surface temperatures sst 28 c in easterly environmental shear jimena maintained constant intensity or weakened gradually for 2 days in 13 20 m s 1 easterly shear olivia intensified in 8 m s 1 shear on the first day overnight the shear diminished to reverse and became westerly on the second day olivia weakened as the shear increased to 15 m s 1 from the west the storm moved over cooler sst and became surrounded by dryer air as convection weakened and the outer rainbands ceased to be effective barriers

the oxygen isotopic composition of olivine and pyroxene from ci chondrites the ci chondrites are taken to represent average solar system material based on the similarity of their elemental compositions to that of the solar photosphere however their oxygen isotope geochemistry is dominated by secondary minerals that formed during aqueous alteration on the ci parent body precursors to this alteration namely olivine and pyroxene are extremely rare in ci chondrites precluding previous measurements of their oxygen isotopic composition we report ion microprobe analyses of oxygen isotopes in single olivine and pyroxene grains separated from ci chondrites orgueil and ivuna the ci chondrite olivine and pyroxene grains most likely represent liberated chondrule phenocrysts based on petrographic chemical and isotopic evidence consistent with crystallization from a melt the oxygen isotope data form an array that falls nearly along the carbonaceous chondrite 16o mixing line with 18o values ranging from 9 3 to 12 3 o and 17o from 11 3 o to 7 8 o consistent with nebular processes being the source of the oxygen isotopic compositions the degree of 16o enrichment in orgueil olivines is negatively correlated with feo content but the exact nature and timing of the process that introduced this variation remains unknown the pyroxene oxygen isotopic compositions are similar to those of olivines with 5 mol fayalite the oxygen isotopic analyses of the olivine and pyroxene in ci chondrites have been used to revise previous models for the isotopic evolution of ci materials our data require more complete gas solid equilibration in the nebula and constrain the initial aqueous fluids on the ci parent body to have lower 17o values than previously postulated the refined model indicates that the temperature of aqueous activity on the ci parent body was no higher than 50 c and the fluid rock ratio was significantly less than previously estimated even prior to alteration and formation of secondary minerals the ci chondrites were the most 16o depleted carbonaceous chondrites and thus the solids originally contained in the ci chondrites are the most equilibrated nebular materials represented in the carbonaceous chondrites the data suggest the oxygen isotopic composition of average solar system to be approximately equivalent to average terrestrial oxygen as recorded in the compositions of terrestrial and lunar basalts

a new kind of primitive chondrite allan hills 85085 abstract allan hills 85085 is a chemically and mineralogically unique chondrite whose components have suffered little metamorphism or alteration this chondrite is unique because it has fewer and smaller chondrules 4 wt mean diameter 16 m than any other chondrite more metallic fe ni 36 and lithic and mineral silicate fragments 56 and a lower abundance of troilite 2 and volatiles most chondrules are cryptocrystalline or glassy and are depleted in volatiles some small chondrules are also very depleted in refractory lithophiles matrix lumps 4 partly resemble ci and cm matrices and may be foreign to the parental asteroid despite these differences the components of alh 85085 have some features common to most type 2 and the least metamorphosed type 3 chondrites metallic fe ni grains that contain 0 1 1 wt cr si and p fe fe mg values of olivines pyroxenes and chondrules are concentrated in the range 1 6 at with a few percent in the range 7 30 porphyritic chondrules are chondritic in composition except for their low volatile abundances thus the components of alh 85085 probably have similar origins to those of components in other chondrites and their properties largely reflect nebular not asteroidal processes the bulk composition of alh 85085 fits none of the nine groups of chondrites it is richer in fe 1 4 ci levels when normalized to si and poorer in na and s 0 1 0 2 ci than other chondrites low volatile concentrations are due to a low matrix abundance and loss of volatiles during or prior to chondrule formation not to volatile loss during metamorphism chondrule textures imply extensive heating of chondrule melts above the liquidus consistent with loss of volatiles from small volumes of melt during chondrule formation the small size of chondrules is partly due to extensive fragmentation by impacts which may have occurred on the parent asteroid or in the solar nebula collisions between chondrule precursor aggregates in the nebula could also be responsible for the small sizes of chondrules assuming that alh 85085 is a representative sample of an asteroid its properties lend support to models for the origins of the earth eucrite parent body and volatile poor iron meteorites that invoke chondritic planetesimals depleted in volatiles the existence of alh 85085 and kakangari suggests that the nine chondrite groups may provide a remarkably poor sample of the primitive chondritic material from which the asteroids formed certain similarities between alh 85085 and bencubbin and weatherford suggest that the latter two primitive meteorites may actually be chondrites with even higher metal abundances 50 60 wt and very large partly fragmented chondrules

directional wind wave coupling in fully coupled atmosphere wave ocean models results from cblast hurricane abstractthe extreme high winds intense rainfall large ocean waves and copious sea spray in hurricanes push the surface exchange parameters for temperature water vapor and momentum into untested regimes the coupled boundary layer air sea transfer cblast hurricane program is aimed at developing improved coupling parameterizations using the observations collected during the cblast hurricane field program for the next generation hurricane research prediction models hurricane induced surface waves that determine the surface stress are highly asymmetric which can affect storm structure and intensity significantly much of the stress is supported by waves in the wavelength range of 0 1 10 m which is the unresolved spectral tail in present wave models a directional wind wave coupling method is developed to include effects of directionality of the wind and waves in hurricanes the surface stress vector is calculated using the two dimensional wave spectra from a wave model with an added short wave s

acfer 182 and paired samples an iron rich carbonaceous chondrite similarities with alh85085 and relationship to cr chondrites three samples of a new fe rich chondrite were found in the sahara in 1990 and 1991 acfer 182 acfer 207 acfer 214 the samples are paired and the meteorite will be designated as acfer 182 the chondrite is chemically texturally and mineralogically similar to the allan hills meteorite alh85085 one important difference between the two meteorites is the smaller average chondrule size in alh85085 the major components of acfer 182 in decreasing abundance are 1 1 highly altered by terrestrial weathering matrix 2 2 mineral and polymineralic silicate fragments and aggregates 3 3 chondrule fragments 4 4 chondrules 5 5 metal 6 6 fine grained dark inclusions the abundance of chondrules is lower and the average chondrule size 90 m smaller than in most other chondrites chondrule fragments are often so large that they cannot be derived from the present chondrule population apparently size sorting has prevented accumulation of the larger parent chondrules several spectacular ca al rich inclusions were found rich in ca dialuminate hibonite or zr y sc bearing phases the chemical composition of acfer 182 and of alh85085 are almost indistinguishable major chemical signatures are 1 1 uniform enrichment of fe and other nonvolatile metals relative to ci chondrites by about 70 2 2 absence of enrichment in refractory lithophiles characteristic of most type 2 and 3 carbonaceous chondrites 3 3 strong depletion of volatile and moderately volatile elements based on the oxygen isotopic composition the chemical composition and the abundances of chondrules and matrix acfer 182 should be classified as a carbonaceous chondrite considering their affinity to carbonaceous chondrites and their high bulk iron content the two meteorites acfer 182 and alh85085 are designated as ch chondrites there are mineralogical and chemical similarities among acfer 182 alh85085 and cr chondrites which distinguish these meteorites from other types of carbonaceous chondrites 1 1 low feo contents of olivine and pyroxene and correspondingly high metal contents 2 2 high cr content in olivine 3 3 abundant fine grained dark inclusions 4 4 abundant ca dialuminate caal4o7 in cais 5 5 similarities in oxygen isotopic composition 6 6 low contents of moderately volatile elements 7 7 low refractory element contents 8 8 presence of a unique component of subsolar rare gases these observations suggest similar conditions of formation for the components of these meteorites a single common parent body is unlikely in view of the differences in chemical composition and in the size distribution of individual components

chassigny petrogenesis melt compositions intensive parameters and water contents of martian magmas abstract the snc meteorites are a class of eight basaltic achondrites that have extremely young crystallization ages 1 3 ga chassigny a unique snc meteorite is a dunite containing fo68 olivines and rare poikilitic ca pyroxenes it is one of the most primitive snc meteorites and thus is most likely to reveal information about the snc basalt source region this study presents a detailed examination of partially crystallized melt inclusions in cumulus olivine grains in chassigny these trapped melts are argued to be representative samples of the melt that existed when chassigny crystallized this melt has been modified however by interaction with the host olivine and by closed system crystallization the phases inside the melt inclusions include hydrous ti rich amphibole kaersutite biotite two pyroxenes and rhyolitic and alkali feldspar glasses all phases have been extensively analyzed with an electron microprobe the new mineralogical information is combined with a complementary experimental study of kaersutite melt equilibria this combined data set can be used to formulate a system of linear equations which can then be solved to determine the composition of the originally trapped melt this calculation reveals that the trapped melt was an feo rich and al2o3 poor basalt the melt composition is shown to be consistent with the crystallization sequence both inside the melt inclusions and in the rock matrix the major element chemistry of this liquid closely resembles terrestrial boninite lavas the new data also allow the intensive conditions temperature total pressure and water fugacity of chassigny crystallization to be estimated two pyroxene geothermometry indicates that equilibration temperatures were 1000 50 c although amphibole does not coexist with melt until t 960 c the trapped liquid initially contained 1 5 wt dissolved water crystallization of anhydrous phases caused water to buildup in the trapped melt prior to kaersutite crystallization the melt must have contained at least 4 wt dissolved water suggesting that a minimum of 1 5 kbar total pressure is required a maximum total pressure cannot be inferred but all available data are consistent with low pressure 5 kbar crystallization finally x h2o in the fluid in the melt inclusion is estimated to have been at least 0 8 in order to stabilize amphibole without plagioclase implying that the water fugacity was 1480 bars the existence of hydrous melts and conditions appropriate for amphibole crystallization suggest that evolved sio2 rich lavas exist on the chassigny parent body mars

alh85085 a unique volatile poor carbonaceous chondrite with possible implications for nebular fractionation processes abstract allan hills 85085 is a unique chondrite with affinities to the al rais renazzo clan of carbonaceous chondrites its constituents are less than 50 m in mean size chondrules and microchondrules of all textures are present nonporphyritic chondrules are unusually abundant the mean compositions of porphyritic nonporphyritic and barred olivine chondrules resemble those in ordinary chondrites except that they are depleted in volatile elements ca al rich inclusions are abundant and largely free of nebular alteration they comprise types similar to those in cm and co chondrites as well as unique types calcium dialuminate occurs in several inclusions metal silicate and sulfide compositions are close to those in cm co chondrites and al rais and renazzo c1 chondrite clasts and metal rich reduced clasts are present but opaque matrix is absent siderophile abundances in alh85085 are extremely high e g fe si 1 7 solar and volatiles are depleted e g na si 0 25 solar s si 0 03 solar nonvolatile lithophile abundances are similar to those in al rais renazzo and cm and co chondrites alh85085 agglomerated when temperatures in the nebula were near 1000 k in the same region where renazzo al rais and the ci chondrites formed agglomeration of high temperature material may thus be a mechanism by which the fractionation of refractory lithophiles occurred in the nebula chondrule formation must have occurred at high temperatures when clumps of precursors were small after agglomeration alh85085 was annealed and lightly shocked c1 and other clasts were subsequently incorporated during late stage brecciation

forced stage response to a moving hurricane abstract the upper ocean s response to three hurricanes norbert 1984 josephine 1984 and gloria 1985 is examined using field observations and a numerical ocean model our goal is to describe the physical processes that determine the structure and amplitude of hurricane driven upper ocean currents all three of these northern hemisphere hurricanes produced a rightward biased response of the mixed layer current and transport this asymmetry arises because the wind stress vector rotates clockwise on the right side of the track and remains nearly parallel with the inertially rotating mixed layer current during most of the hurricane passage the maximum observed mixed layer current varied from 0 8 m s 1 in response to josephine which was a large but comparatively weak hurricane to 1 7 m s 1 in response to gloria which was very large and also intense these cases have been simulated with a three dimensional numerical model that includes a treatment of wind driven vertical mixing within the primitive

hurricane directional wave spectrum spatial variation in the open ocean abstract the sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane s inner core over open water the nasa airborne scanning radar altimeter sra carried aboard one of the noaa wp 3d hurricane research aircraft at 1 5 km height acquired the open ocean data on 24 august 1998 when bonnie a large hurricane with 1 min sustained surface winds of nearly 50 m s 1 was about 400 km east of abaco island bahamas the noaa aircraft spent more than five hours within 180 km of the eye and made five eye penetrations grayscale coded images of hurricane bonnie wave topography include individual waves as high as 19 m peak to trough the dominant waves generally propagated at significant angles to the downwind direction at some positions three different wave fields of comparable energy crossed each other partitioning the sra directional wave spectra enabled determination of the characteristics of the various components of the hurricane wave field and mapping of their sp

middle ordovician chondrite in fossiliferous limestone from brunflo central sweden the few discoveries of fossil meteorites have been attributed1 to the ignorance about the appearance of meteorites among palaeontologists and other geologists who examine limestone quarries coal mines and other excavations in sedimentary rocks we now report the first find of a fossil stony meteorite in ordovician limestone the meteorite is a chondrite possibly an h chondrite and its terrestrial age is 463 myr the fine structural details of the chondrules are often extremely well preserved but the chemical composition and the mineralogy have changed dramatically chromite being the only primary mineral preserved the present major minerals are calcite barite a cr v phengite and a cobaltite group mineral

presolar diamond sic and graphite in primitive chondrites abundances as a function of meteorite class and petrologic type abstract acid resistant residues were prepared for eighteen meteorites from seven chondrite classes using improved procedures designed to minimize loss of presolar grains noble gases were measured by stepped pyrolysis and the abundances of five exotic noble gas components were used to determine abundances of diamond sic and graphite diamond separates were prepared to check diamond abundances determined from noble gases diamond and sic were found in unmetamorphosed members of all seven chondrite classes and evidence for graphite was found in orgued ci and ll3 0 3 1 chondrites our data and noble gas and stable isotope data in the literature show that presolar grains were incorporated into all chondrite classes the grains are sited in the fine grained matrix and their abundances within the matrix reflect mainly the degree of metamorphism suffered by the host meteorite the pattern of metamorphic destruction differs from class to class in unequilibrated ordinary chondrites uocs graphite is most easily destroyed followed by sic and then diamond no presolar grains remain in uocs of petrologic type 3 8 whose matrices have been completely recrystallized in eh chondrites diamond and sic survive much more severe metamorphism than in uocs with sic apparently more stable than diamond presolar graphite was not detected in cv3 and c03 chondrites diamond appears to be more stable than sic and graphite again is missing inferred premetamorphic diamond abundances matrix normalized vary by a factor of 2 2 between classes with eh cv and co chondrites having higher initial abundances than orgueil similar diamond sic ratios are observed in most classes and differences in the ratio can be tied to secondary processing suggesting that all chondrite classes sampled the same solar system wide reservoir of presolar grains differences in initial abundances between classes appear to correlate with chemical and physical properties of the host meteorites these bulk properties and variations in presolar grain abundances both may be the result of thermal processing of presolar dust in the accretion disk

on the characteristic height scales of the hurricane boundary layer in this study data from 794 gps dropsondes deployed by research aircraft in 13 hurricanes are analyzed to studythecharacteristicheightscalesofthehurricaneboundarylayer theheightscalesaredefinedinavariety of ways the height of the maximum total wind speed the inflow layer depth and the mixed layer depth the height of the maximumwind speed and the inflow layerdepth are referred to asthe dynamical boundarylayer heights while the mixed layer depth is referred to as the thermodynamical boundary layer height the data analyses show that there is a clear separation of the thermodynamical and dynamical boundary layer heights consistent with previous studies on the boundary layer structure in individual storms the dynamical boundary layer height is found to decrease with decreasing radius to the storm center the thermodynamic boundary layer height which is much shallower than the dynamical boundary layer height is also found to decrease with decreasing radius to the storm center the results also suggest that using the traditional critical richardson number method to determine the boundary layer height may not accurately reproduce the height scale of the hurricane boundary layer these different height scales reveal the complexity of the hurricane boundary layer structure that should be captured in hurricane model simulations

mineralogy and composition of matrix and chondrule rims in carbonaceous chondrites abstract the degree of compositional variation of fine grained minerals displayed by the members within any carbonaceous chondrite group i e ci cm cv cr is a direct reflection of the range of aqueous alteration assemblages present matrix and fine grained chondrule rims within any particular carbonaceous chondrite are mineralogically nearly identical to one another but not necessarily similar in bulk elemental composition even though they have subsequently experienced post accretional secondary processing aqueous alteration under identical conditions this may indicate preferential alteration of one component brecciation exchange of components between rims and matrix and or accretion of matrix and rims from mineralogically or compositionally distinct materials we propose that co chondrites experienced parent body conditions of low f o2 low water rock ratios and temperatures below 50 c cr chondrites experienced higher water rock ratios potentially higher temperatures 150 c and a wide range of f o2 the alteration mineralogy of cv chondrites indicates water rock ratios at the high end at least of the range for cr chondrites essebi and mac 87300 cm chondrites experienced temperatures below 50 c low f o2 and low water rock ratios except eet 83334 which probably experienced relatively higher f o2 and b 7904 and y 86720 which experienced postalteration temperatures in the range 500 700 c most ci chondrites experienced temperatures between 50 and 150 c relatively high water rock ratios and variable f o2 with a late stage increase in the latter due possibly to brecciation and consequent release of methane y 82162 witnessed post alteration heating possibly as high as 400 c

shock metamorphism of ordinary chondrites a revised petrographic classification of progressive stages of shock metamorphism of ordinary chondrites is proposed six stages of shock s1 to s6 are defined based on shock effects in olivine and plagioclase as recognized by thin section microscopy the characteristic shock effects of each shock stage are s1 unshocked sharp optical extinction of olivine s2 very weakly shocked undulatory extinction of olivine s3 weakly shocked planar fractures in olivine s4 moderately shocked mosaicism in olivine s5 strongly shocked isotropization of plagioclase maskelynite and planar deformation features in olivine and s6 very strongly shocked recrystallization of olivine sometimes combined with phase transformations ringwoodite and or phases produced by dissociation reactions s6 effects are always restricted to regions adjacent to melted portions of a sample which is otherwise only strongly shocked in stages s3 to s6 localized melting results from stress and temperature peaks which locally deviate from the equilibration shock pressure due to differences in shock impedance these melting effects are a opaque melt veins shock veins b melt pockets with interconnecting melt veins c melt dikes and d troilite metal deposits in fractures based on a critical evaluation of data from shock recovery experiments a shock pressure calibration for the six shock stages is proposed which defines the s1 s2 s2 s3 s3 s4 s4 s5 and s5 s6 transitions at 5 5 10 15 20 30 35 and 45 55 gpa respectively whole rock melting and formation of impact melt rocks or melt breccias occurs at about 75 90 gpa the symbol for the shock stage may be used in combination with the symbol for the petrologic type to abbreviate the complete classification of a chondrite e g h5 s3 we propose this new shock classification and pressure calibration system to replace previous systems which are out of date with respect to the pressure calibration nominally restricted to l chondrites and based on incomplete and in part illdefined sets of shock effects we have classified seventy six ordinary chondrites using the new classification system and conclude the following 1 1 shock effects and the sequence of progressively increasing degrees of shock metamorphism are very similar in h l and ll groups differences in the frequency distribution of shock stages are relatively minor e g l chondrites appear to have the largest fraction with stages s5 and s6 this suggests that the collisional histories of the h l and ll parent bodies were similar 2 2 petrologic type 3 chondrites are deficient in stages s4 to s6 and with increasing petrologic type the frequency of stages s4 to s6 increases we suggest that the more porous and volatile rich type 3 chondrites are subject to melting at a lower shock pressure than the nonporous chondrites of higher petrologic type volatiles trapped in pores cause shock induced dispersal of the shocked and melted material into small particles which are not expected to survive as meteorites 3 3 stage s3 is the most abundant in nearly all petrologic types 4 4 at shock pressures in excess of about 35 gpa s5 and s6 4he and 40ar are almost completely lost pressures below 10 gpa s1 and s2 do not cause noble gas losses

the kaidun meteorite composition and origin of inclusions in the metal of an enstatite chondrite clast metal nodules are one of the major textural components of kaidun sample 01 3 06 eh3 4 in terms of structure the nodules are of three types 1 globular 2 zoned with a massive core and globular mantle and 3 nodules with no internal structure the size and composition of the globules in the nodules and grains of metal of the matrix are almost identical no greater than 20 m and ni 5 95 si 3 33 wt the nodules contain small usually 5 m inclusions of sio2 albitic glass enstatite roedderite and a mixture of sio2 and na2s2 this is the first reported occurrence of a simple sulfide of an alkaline metal in nature the formation of the inclusions appears to be related to condensation of material onto the surfaces of metal grains the nodules appear to have formed by aggregation of separate grains globules of metal with conservation of condensates on the grain surfaces as inclusions the inclusions probably condensed over a significant temperature range from 1400 to 600 k the aggregation of metal grains and formation of the nodules probably occurred simultaneously with condensation

carbonate compositions in cm and ci chondrites and implications for aqueous alteration abstract carbonate minerals in fourteen cm chondrites and two ci chondrites have been analyzed by electron microprobe to provide a better understanding of the aqueous processes that affected carbonaceous chondrite parent bodies calcites in cm chondrites and dolomites and magnesites in ci chondrites display the compositions expected of stable phases formed at low temperatures dolomites in cm chondrites identified here for the first time in five members of the group have small amounts of excess ca which may reflect metastable growth the distribution of fe between dolomite and coexisting serpentine differs in the two chondrite groups if the distributions reflect an approach to chemical equilibrium then the difference implies higher alteration temperatures for the ci group than the cm group in agreement with the results of previously published oxygen isotope thermometry and mineral solubility modeling of the alteration process dolomite fe contents are relatively uniform in the two chondrite groups dolomite mn contents by contrast vary widely the variations may reflect transport controlled coprecipitation of mn resulting from a heterogeneous distribution of the element in the anhydrous precursor material if this interpretation is correct then the altering fluids were essentially immobile while hydration reactions proceeded on the meteorite parent bodies the near closed system character of the alteration process long known from bulk chemical analyses of the meteorites is a direct consequence of the limited mobility of dissolved species

clay mineraloid weathering products in antarctic meteorites abstract clay mineraloids are associated with gypsum k fe sulfates possibly jarosite cryptocrystalline rust and possibly with zeolites and or secondary alkali feldspars as terrestrial weathering products in stony meteorites from the allan hills alh and elephant moraine eet collection areas in victoria land antarctica weathering formed fracture fillings in fusion crusts of eucrites eeta79004 and eeta79005 diogenites alha77256 and eeta79002 shergottite eeta79001 and h5 chondrite alh82102 and decomposition products of glass and plagioclase in interior samples of achondrites clay mineraloids displayed massive to incipient vermicular forms with elemental compositions that suggest smectite and mica like phases deposits were too small to yield pure material for phase identification although x ray diffractometry and differential scanning calorimetry of bulk samples suggested that the clay mineraloids were not well crystallized a typical structural formula calculated on a smectite basis follows k 0 26 ca 0 04 al 0 97 ti 0 02 fe 3 0 77 mg 0 03 si 4 00 o 10 oh 2 n 2 o net charge 0 28 excessions 0 58 si 0 02 cl 0 09 so 4 0 02 po 4 hydrocryogenic diagenesis can initiate clay mineral formation on timescales of 10 4 10 6 y even with only limited supplies of liquid water cosmochemists must take care not to confuse possible weathering induced elemental and isotopic fractionations in antarctic meteorite samples with signatures of pre terrestrial cosmic processes given proper sample selection and testing though occurrence of clay mineraloid and other weathering products should probably not impede progress in studies of antarctic meteorites

mineralogy of meteorite groups approximately 275 mineral species have been identified in meteorites reflecting diverse redox environments and in some cases unusual nebular formation conditions anhydrous ordinary carbonaceous and r chondrites contain major olivine pyroxene and plagioclase major opaque phases include metallic fe ni troilite and chromite primitive achondrites are mineralogically similar the highly reduced enstatite chondrites and achondrites contain major enstatite plagioclase free silica and kamacite as well as nitrides a silicide and ca mg mn na cr k and ti rich sulfides aqueously altered carbonaceous chondrites contain major amounts of hydrous phyllosilicates complex organic compounds magnetite various sulfates and sulfides and carbonates in addition to kamacite and taenite iron meteorites contain carbides elemental c nitrides phosphates phosphides chromite and sulfides silicate inclusions in iab iiicd and iie iron meteorites consist of mafic silicates plagioclase and various sulfides oxides and phosphates eucrites howardites and diogenites have basaltic to orthopyroxenitic compositions and consist of major pyroxene and calcic plagioclase and several accessory oxides ureilites are made up mainly of calcic chromian olivine and low ca clinopyroxene embedded in a carbonaceous matrix accessory phases include the c polymorphs graphite diamond lonsdaleite and chaoite as well as metallic fe ni troilite and halides angrites are achondrites rich in fassaitic pyroxene i e al ti diopside minor olivine with included magnesian kirschsteinite is also present martian meteorites comprise basalts lherzolites a dunite and an orthopyroxenite major phases include various pyroxenes and olivine minor to accessory phases include various sulfides magnetite chromite and ca phosphates lunar meteorites comprise mare basalts with major augite and calcic plagioclase and anorthositic breccias with major calcic plagioclase several meteoritic phases were formed by shock metamorphism martensite 2 fe ni has a distorted body centered cubic structure and formed by a shear transformation from taenite during shock reheating and rapid cooling the c polymorphs diamond lonsdaleite and chaoite formed by shock from graphite suessite formed in the north haig ureilite by reduction of fe and si possibly from olivine via reaction with carbonaceous matrix material ringwoodite the spinel form of mg fe 2sio4 and majorite a polymorph of mg fe sio3 with the garnet structure formed inside shock veins in highly shocked ordinary chondrites secondary minerals in meteorite finds that formed during terrestrial weathering include oxides and hydroxides formed directly from metallic fe ni by oxidation phosphates formed by the alteration of schreibersite and sulfates formed by alteration of troilite

the dynamics of boundary layer jets within the tropical cyclone core part i linear theory abstract observations of wind profiles within the tropical cyclone boundary layer have until recently been quite rare the recent massive increase in observations due to the operational implementation of the global positioning system dropwindsonde has emphasised that a low level wind speed maximum is a common feature of the tropical cyclone boundary layer here is proposed a mechanism for producing such a maximum whereby strong inward advection of angular momentum generates the supergradient flow the processes that maintain the necessary inflow against the outward acceleration resulting from gradient wind imbalance are identified as being i vertical diffusion ii vertical advection and iii horizontal advection two complementary tools are used to diagnose the properties and dynamics of the jet the first presented here is a linear analytical model of the boundary layer flow in a translating tropical cyclone it is an extension of the classical ekman boundary layer model as well as of earlier w

aqueous alteration and brecciation in bells an unusual saponite bearing cm chondrite the petrological and mineralogical characteristics of the unusual cm2 chondrite bells have been investigated in detail by scanning electron microscopy sem electron microprobe analysis epma and transmission electron microscopy tem bells is a highly brecciated chondrite which contains few intact chondrules a very low abundance of refractory inclusions and is notable in having an unusually high abundance of magnetite which is disseminated throughout the fine grained matrix fragmental olivines and pyroxenes are common and based on compositional data appear to have been derived from chondrules as a result of extensive brecciation the fine grained mineralogy of matrix in bells differs considerably from other cm chondrites and has closer affinities to matrix in ci chondrites the dominant phases are fine grained saponite interlayered with serpentine and phases such as tochilinite and cronstedtite which are typical of cm chondrite matrices are entirely absent pentlandite pyrrhotite magnetite anhydrite calcite and rare ti oxides also occur as accessory phases based on its oxygen and noble gas isotopic compositions zadnik 1985 rowe et al 1994 bells can be considered to be a cm2 chondrite although its bulk composition shows some departures from the typical range exhibited by this group however these variations in bulk chemistry are entirely consistent with the observed mineralogy of bells the unusual fine grained mineralogy of bells matrix can be reasonably attributed to the combined effects of aqueous alteration and advanced brecciation in a parent body environment extensive brecciation has assisted aqueous alteration by reducing chondrules and mineral grains into progressively smaller grains with high surface areas which are more susceptible to dissolution reactions involving aqueous fluids this has resulted in the preferential dissolution of fe rich chondrule olivines which are now completely absent in bells although present in other cm chondrites the formation of saponite in bells probably resulted from the dissolution of relatively silica rich phases such as pyroxene and olivine that were derived from chondrules the result of such dissolution reactions would be to increase the activity of silica in the fluid phase at least on a localized scale stabilizing saponite in preference to serpentine an increase in asio2 would also have destabilized preexisting cronstedtite which may have reacted to form magnetite and mg fe serpentine under conditions of constant o2

primary magmatic carbon in ureilites evidence from cohenite bearing metallic spherules metallic spherules containing cohenite fe ni metal sulfides and rare phosphorus bearing minerals occur as inclusions within olivine and pigeonite grains in five low shock ureilites the bulk compositions mineralogy and textures of these spherules indicate that they represent fe ni c s alloys that existed as droplets of immiscible metallic liquid in the magma s from which ureilites crystallized at magmatic temperatures these alloys were carbon saturated and probably coexisted with graphite in the magma this is consistent with the occurrence of graphite crystals as inclusions in olivine in some ureilites and supports the view that graphite in ureilites was a primary magmatic component graphite could have been a residue from the solid source materials that melted to produce the ureilite parent magma s or could have crystallized from the magma s the metallic liquids separated into immiscible fe c liquids and fe s liquids after they were trapped within silicates the fe c liquids contained 4 5 wt c and 3 7 wt ni cohenite was the liquidus phase and started to crystallize at 1200 1225 c forming euhedral and subhedral crystals at the eutectic 1175 c iron containing 7 9 ni and 1 8 c crystallized along with cohenite at lower temperatures the iron exsolved cohenite and possibly iron

magmatic activity on the iva parent body evidence from silicate bearing iron meteorites abstract four of the magmatic iva iron meteorites contain tridymite or clinobronzite orthobronzitetridymite which are quite unlike silicate assemblages in other iron meteorites the textures the bulk chemistry and the zoning preserved in the pyroxenes strongly suggest that they are igneous cumulates the pyroxenes have extremely low fe mn ratios less than 20 and low contents of rees and other incompatible elements these cumulates crystallized from magmas of unusual composition with some similarity to terrestrial boninites at the protobronzite tfdymite cotectic in the olivine plagioclase silica system a liquidus temperature in the range 1400 1350 c was inferred for the steinbach meteorite from the estimated distribution coefficient for cr in pyroxene dcrsolid liquid 0 66 the low levels of incompatible elements show that less than 1 of the residual liquid was trapped in the cumulates during cooling at subsolidus temperatures most of the protobronzite transformed to orthobronzite and the rest inverted to a fine inter growth of clino and orthobronzite in addition the igneous zoning of ca fe mg and mn was modified by diffusion whereas ti al and cr were not or only slightly affected the silica saturated magmas could not have evolved in an olivine rich mantle we assume that the magmas became incorporated in the metal core possibly due to solidification shrinkage of the metal we propose that the iva parent magmas were formed by high degrees of partial melting 40 of a chondritic precursor along the olivine pyroxene peritectic reaction curve in the olivine plagioclase silica system at low pressures the precursor may have been depleted in incompatible elements by a preceding melting episode the partial melts were then separated from the olivine residue and subsequently reduced to account for the low fe mn ratios and the unusually high si content

the influence of the ocean on typhoon nuri 2008 abstracttyphoon nuri 2008 was 1 of approximately 120 typhoons in the past 60 years that passed through a narrow gap the luzon strait connecting the western north pacific and the south china sea scs in total 70 of these storms including nuri reached their maximum intensities over the warm waters east of luzon and in the kuroshio then rapidly weakened in the scs numerical experiments were conducted to understand the intensity change of nuri westward across the kuroshio in the luzon strait the 26 c isotherm shallows rapidly by half this and stronger mixing by wind ocean resonance preferentially cooled sea surface temperature and weakened the typhoon in scs a positive feedback mechanism is then described to explain the intensification of nuri over the western north pacific

the polymict eucrites the polymict eucrites are a suite of about 14 polymict achondritic meteorites that contain at least 90 vol of eucritic material and are found both in antarctica and elsewhere they are part of a continuum of polymict breccias that includes howardites and polymict diogenites rare gas data suggest that some are gas rich regolith breccias the clasts contained in polymict eucrites sample a variety of lithologies from their parent body and include eucritic clasts alkali enriched eucrites pyroxene cumulate eucrites two pyroxene mafic rocks possibly feldspar cumulate eucrites diogenites fayalitic lithologies and a variety of other mineral clasts the eucritic clasts are probably samples of near surface lithologies on the parent body but the presence of two pyroxene mafic rocks is considered to be evidence of magmatic activity at pressures in excess of 1 kbar in the parent body partial melt models may explain some of the diversity among the clasts but cumulus processes are believed to have been important if pressures greater than 1 kbar are confirmed then the basaltic achondrite parent body bap must have a diameter in excess of 200 km the variety of lithologies suggests that not all basaltic achondrites are samples of igneous rocks formed by single stage melting of a chondritic asteroid but are instead samples of an evolved and diverse crust produced by serial magmatism

the microstructure of semarkona and bishunpur abstract the ordinary chondrites semarkona and bishunpur appear to have experienced in situ hydrous alteration here we report the results of the first detailed tem examination of them which supports this conclusion in semarkona all but the most magnesian mafic minerals have been destroyed and primary sulphides most likely troilite have been partially altered to phyllosilicates and ni rich pyrrhotite in bishunpur alteration is confined to the production of smectite from an amorphous feldspathic material in the chondrule rims and interchondrule matrix during hydrous alteration of both meteorites the temperature probably did not exceed 260 c the equilibrium composition of the gas present during the alteration of semarkona was not solar but was dominated by h2o the formation of smectite does not require the presence of liquid water however evidence for the redistribution of elements such as ca zn and si over tens of microns or more implies that there was at least some transient grain boundary fluid present the alteration in semarkona and bishunpur is far from complete thermodynamic modelling suggests that more altered ordinary chondrites would be mineralogically similar to the cm and ci carbonaceous chondrites superficially the mineralogy mineral chemistry and bulk chemistry of semarkona matrix rims resemble those of some chondritic interplanetary dust particles cidps the ordinary chondrite parent bodies may therefore be a source of some cidps

coupled atmosphere ocean wave simulations under high wind conditions abstract the impact of ocean surface waves on the structure and intensity of three tropical cyclones and a topographically forced bora event is investigated using a coupled atmosphere ocean wave modeling system the coupled system is capable of representing surface momentum fluxes that are enhanced due to young ocean waves in fetch limited conditions which yield surface roughness lengths that significantly depart from the conventional charnock type formulation in general the impact of ocean wave induced stress on the tropical cyclone central pressure was quite variable with ocean wave feedback resulting in changes ranging from 8 hpa deeper to 3 hpa shallower the increased low level stress due to the ocean waves reduced the near surface winds by 2 3 m s 1 with local differences in excess of 10 m s 1 which directly led to a 10 reduction in the significant wave height maxima the reduced significant wave heights in the coupled model were in closer agreement with observations for tropical cyclone bonni

carlisle lakes and allan hills 85151 members of a new chondrite grouplet carlisle lakes and allan hills 85151 alh85151 are members of a new grouplet of chondrites characterized by feo rich silicates olivine fa 38 41 mol unusual oxygen isotopic composition and abundant 35 vol recrystallized matrix material yamato 75302 is not as well characterized but is probably also a member of this grouplet siderophile elements in carlisle lakes and alh85151 are fractionated relative to ci chondrites refractory and common siderophiles are at 1 ci ga and as are lower 0 6 0 9 ci and au is very low 0 17 ci and 0 36 ci in carlisle lakes and alh85151 respectively the low au abundance may indicate that au resided mainly in fine grained metal particles that were suspended in the nebular gas during the time these chondrites agglomerated the oxidation state of chondrites may be controlled by the presence of oxidizing agents e g magnetite in agglomerated matrix material the high matrix abundance that characterizes this new grouplet may thus be responsible for the high oxidation state of these meteorites

symmetric and asymmetric structures of hurricane boundary layer in coupled atmosphere wave ocean models and observations abstractit is widely accepted that air sea interaction is one of the key factors in controlling tropical cyclone tc intensity however the physical mechanisms for connecting the upper ocean and air sea interface with storm structure through the atmospheric boundary layer in tcs are not well understood this study investigates the air sea coupling processes using a fully coupled atmosphere wave ocean model especially the coupling induced asymmetry in surface winds sea surface temperature air sea fluxes and their impacts on the structure of the hurricane boundary layer hbl numerical experiments of hurricane frances 2004 with and without coupling to an ocean model and or a surface wave model are used to examine the impacts of the ocean and wave coupling respectively model results are compared with the airborne dropsonde and surface wind measurements on board the noaa wp 3d aircraft the atmosphere ocean coupling reduces the mixed layer depth in the rear right quadrant due to storm induced ocean

origin of metallic fe ni in renazzo and related chondrites abstract the anomalous positive co ni correlation among metal grains from the renazzo and al rais chondrites reported in previous studies has two components 1 1 a chondrule trend that extends up to 120 145 mg g ni probably reflects the mixing of fe rich and fe poor nebular metal and 2 2 a weak extrachondrule trend that spans a ni range from 40 70 mg g reflects fe introduction during mild metamorphism to assess the formation of this metal we determined ni and co zoning profiles in metallic fe ni from different petrographic sites chondrule interiors chondrule margins chondrule rims and matrix in renazzo al rais and the related chondrite macalpine hills 87320 metal from chondrule interiors shows flat ni and co concentrations and profiles moderately large grain to grain compositional variations even within chondrules and generally high ni and co nickel concentrations extend above the kamacite stability limit etching such martensite shows high ni domains in some cases but observed ni concentrations do not exceed 190 mg g metal from chondrule margins adjacent to matrix shows convex inverted u shaped ni and co zoning profiles the highest ni and co concentrations are at grain centers although the mean central ni and co concentrations in margin grains are much lower than those in metal from chondrule interiors about half of the matrix metal shows flat co and ni profiles like those from chondrule interiors the remainder are convex the differences in mean co and ni contents between chondrules and extrachondrule materials may reflect differential sampling of nebular metal grains having compositions that varied with particle size we interpret the low co and ni contents at the edges of grains in chondrule margins to reflect dilution by fe produced by feo reduction the reduction seems not to have occurred in the nebula but rather during a brief period of parent body metamorphism reduction of fine grained feo produced metallic fe that plated onto nearby metal grains although diffusive exchange between pentlandite and metal could produce the observed ni gradient it is doubtful that it could produce the similar gradient of co metal from chondrule interiors was inaccessible during the reduction event and retained the flat profiles established during chondrule formation

matrix mineralogy of the orgueil ci carbonaceous chondrite a petrographic and transmission electron microscopic study of the orgueil ci carbonaceous chondrite shows that the matrix consists mainly of fe bearing mg rich serpentine and smectite saponite as well as a poorly crystallized fe rich material that contains minor variable s and ni the fe rich material is probably ferrihydrite a ferric hydroxide the ferrihydrite occurs in small particles 80 a in diameter and the s and ni are probably adsorbed on its surfaces the serpentine and saponite occur in poorly crystallized fine crystallites fine phyllosilicates that are intimately associated with the ferrihydrite coarsely crystallized phyllosilicates coarse phyllosilicates occur in clusters relatively free of ferrihydrite the ferrihydrite is a major matrix constitutent and probably accounts for most of the fe3 as well as the superparamagnetic fraction in the orgueil matrix the textures suggest that the fine phyllosilicates resulted from alteration of the coarse phyllosilicates the alteration probably involved a substantial amount of water and coincided with the period of sulfate vein formation during the aqueous alteration magnetite grains disaggregated from framboids and fe ni sulfides were replaced by ferrihydrite simultaneously aqueous solutions reacted with the coarse phyllosilicates and precipitated ferrihydrite producing intimate pervasive mixtures with the fine phyllosilicates the matrix mineralogy of the orgueil chondrite suggests that orgueil experienced considerably different alteration conditions from the cm chondrites the mineralogical and petrological differences between ci and cm chondrites can not simply be explained as the result of different degrees of aqueous alteration

slab and height resolving models of the tropical cyclone boundary layer part i comparing the simulations diagnostic models of the tropical cyclone boundary layer have important practical uses including engineering design and climatological risk assessment studies and as components of tropical cyclone potential intensity models a widely used class of such models has been slab models in which the governing equations are depth averaged here a slab model is compared with one that fully resolves height and it is shown that the vertical averaging leads to substantial differences in the simulations the slab model produces excessively strong inflow and too great a departure of the boundary layer mean winds from gradient balance in moving storms the slab models produce much too strong a motion induced asymmetry and can support an asymmetric analogue of the quasi inertial oscillation previously noted in axisymmetric slab models given the considerable impact of the vertical averaging in slab models on the simulated flow in the tropical cyclone boundary layer it is difficult to recommend their further use for applications where quantitative accuracy is important other applications will require care to ensure that the results are not unduly affected by the depth averaging part ii of this article presents a detailed analysis of the reasons for the differences between depth averaged and height resolving simulations of the tropical cyclone boundary layer 2010 published by john wiley sons ltd

classification of mafic clasts from mesosiderites implications for endogenous igneous processes we have analyzed thirteen igneous pebbles from the vaca muerta eet87500 and bondoc mesosiderites by electron microprobe and instrumental neutron activation and combined these data with literature data for forty three analyzed mesosiderite clasts we classify these well characterized clasts into the following five principal groups 1 1 polygenic and monogenic cumulates 39 are coarse grained gabbros that are highly depleted in incompatible elements relative to h chondrites they formed at moderate depth either as residues of low degree partial melting of pre existing cumulate eucrites or as cumulates from parent melts similar to cumulate eucrites 2 2 polygenic basalts 30 are finer grained rocks with positive europium anomalies la lu ratios 1 and lower rare earth element abundances than basaltic eucrites it seems likely that these rocks were formed near their parent body surface by remelting mixtures of major amounts of basaltic eucrites and lesser amounts of cumulate eucrites 3 3 quench textured rocks comprise two compositional groups a those which resemble basaltic eucrites 5 and b those which resemble cumulate eucrites 2 the quench textured rocks are probably monogenic they formed most likely when small scale impacts at their parent body surface totally melted small amounts of basaltic or cumulate eucrite material 4 4 monogenic basalts 11 resemble basaltic eucrites and formed by endogenous igneous processes on the mesosiderite parent body mpb the monogenic basalts and those quench textured rocks that resemble basaltic eucrites in composition plot subparallel to the nuevo laredo trend eucrites on diagrams of incompatible element concentration vs mg previous work has shown that the nuevo laredo trend eucrites were probably produced by fractional crystallization it seems likely that the monogenic basalts from the mpb had a similar origin 5 5 ultramafic rocks are cumulates consisting mainly of large crystals of orthopyroxene 9 or olivine 4 orthopyroxenite clasts closely resemble diogenites and were formed most likely by endogenous igneous processes olivine crystals vary significantly in major element composition some may be endogenous but others may have been derived from the disrupted mantle of a different parent body

a comparative study of opaque phases in qingzhen eh3 and macalpine hills 88136 el3 representatives of eh and el parent bodies opaque minerals in the qingzhen eh3 and macalpine hills mac 88136 el3 enstatite chondrites were studied and compared with other eh and el chondrites all opaque minerals usually occur in multi sulfide metal clasts and nodules in the matrix between chondrules el goresy et al 1988 the higher abundance of opaque minerals the occurrence of niningerite and various alkali sulfides e g caswellsilverite phases a and b djerfisherite are diagnostic criteria for eh chondrites while alabandite is characteristic for el chondrites in addition eh chondrites are characterized by enrichments of si in both kamacite and perryite and alkali elements in sphalerite and chalcopyrite the mn contents of daubreelite and sphalerite are lower in eh than in el chondrites these are consistent with lower oxygen fugacity and higher h2s fugacity of eh than el chondrites in contrast the discovery of sphalerite and zn rich daubreelite in mac 88136 indicates that their absence in el6 chondrites is probably related to thermal metamorphism in the parent body schreibersite microspherules are commonly enclosed in most sulfides in qingzhen but are absent in mac 88136 they were once molten and probably predated all sulfide host phases the petrographic setting and chemical compositions of the sulfide hosts of the schreibersite microspherules in eh3 chondrites are consistent with formation by condensation the earliest sulfide condensates oldhamite and niningerite occupy the interiors of the clasts and nodules whereas the rims consist of troilite and djerfisherite in addition in qingzhen some other troilite djerfisherite and sphalerite assemblages coexist with perryite they were produced by sulfurization of metallic fe ni in the nebula in mac 88136 sulfurization of si bearing fe ni metal is less pronounced and it produced troilite schreibersite and less abundant perryite two kinds of normal zoning and a reverse zoning trends of niningerite and both normal and reverse zoning of sphalerite were found in clasts and nodules in qingzhen the coexistence of normal and reverse zoning profiles in niningerite grains in the same meteorite strongly suggests that they formed before accretion in the parent body because an asteroidal metamorphic or an impact event in the parent body would have erased these contrasting profiles and destroyed the textural settings in contrast alabandite in mac 88136 shows only normal zoning with the fes content decreasing to 9 3 mol toward troilite indicating very slow cooling at low temperature

reply to comments on symmetric and asymmetric structures of hurricane boundary layer in coupled atmosphere wave ocean models and observations in our original paper lee and chen 2012 hereafter lc12 we documented the three dimensional 3d structure in hurricane frances s 2004 boundary layer using both observations and a coupled atmosphere wave ocean model namely the university of miami coupled model umcm zhang et al 2014 hereafter z14 raised a few questions mainly on some perceived differences between lc12 and a previous study by zhang et al 2011 hereafter z11 we stand by our original results and conclusions and provide some specific responses to z14 the following numbers are corresponding to the sections in z14

impact melt products of chondritic material a large variety of objects in chondritic meteorites formed as a result of impact melting shock veins metal troilite mixtures metal and sulfide nodules melt pockets vugs agglutinates glassy and crystalline spherules and numerous types of melt rock clasts the type of object produced in an impact event is related to the interaction of the shock waves with the particular target rock impact melting has also affected large portions of several chondrite breccias many of these contain vugs and patches of silicate glass some workers have suggested that various iron meteorites including groups iab iiicd and iie as well as several ungrouped irons were formed from individual impact melt pools in chondritic regoliths the eagle station trio pallasites and several ungrouped meteorites bencubbin weatherford enon acapulco and allan hills a77081 may have formed from impact melted chondritic material it is also possible that the parent magmas of ureilites were derived from impact melted metal rich carbonaceous chondrite material

carbide magnetite assemblages in type 3 ordinary chondrites abundant carbide magnetite assemblages occur in matrix chondrules and chondrule rims in several h3 l3 and ll3 chondrites carbides cohenite fe ni 3c and haxonite fe ni 23c6 show compositional variations between different meteorites and appreciable ranges within meteorites carbides in h chondrites have lower co contents 0 0 6 wt than those in l and ll chondrites 0 3 1 2 wt metal associated with carbides and magnetite consists of high ni 50 70 wt taenite and in l and ll chondrites co rich up to 35 wt kamacite minor element contents of troilite and magnetite are very low textural observations indicate that carbide magnetite assemblages formed by replacement of metal sulfide nodules the high co contents of residual kamacite in association with carbides indicates that co is not incorporated into carbides i e fe co is much higher in the carbides than in kamacite because ni in carbides and magnetite is low the ni contents of residual taenite tend to be high ni rich sulfides were found only in ll3 chondrites possibly indicating their more extensive oxidation and or aqueous alteration we suggest that carbide magnetite assemblages in type 3 ordinary chondrites formed as the result of hydrothermal alteration of metallic fe in metal troilite nodules by a coh bearing fluid on their parent bodies this alteration resulted in carbidization of feni metal probably by co gas e g 15 fe s 4 co g fe3c s fe3o4 s or 3 fe s 2 co g fe3c s co2 g and oxidation probably by h2o gas e g 3fe s 4h2o g fe3o4 s 4h2 g the coh bearing fluids which were possibly released during metamorphism and transported through zones of high permeability may have been derived from ices adsorbed gases or hydrated minerals the co may be the result of the reaction of carbon compounds e g hydrocarbons with water vapor or magnetite

allan hills 85085 a subchondritic meteorite of mixed nebular and regolithic heritage abstract allan hills 85085 is a tiny 12 g meteorite whose closest relatives are the renazzo and al rais chondrites and the subchondritic host material in the bencubbin meteorite its bulk composition is generally chondritic but siderophile abundances are tens of per cent higher and abundances of moderately volatile elements factors of 2 4 lower than in known authentic chondrites in addition to this unusual composition alh85085 has an extremely small particle size metal that shows no evidence of metamorphic equilibration and a very high abundance of pyroxenitic lithic particles chondrules are rare and small most are pyroxenitic and chemically similar to the lithic particles previous workers have inferred that most or all of these strange features of alh85085 resulted from nebular processes but we suggest that melting vaporization outgassing condensation and size sorting in a cloud of impact ejecta offer a more viable alternative until additional similar materials have been discovered and characterized it seems safest to infer nebular properties and processes on the basis of the record in chondrites regarding which there is little doubt that nebular processes were dominant

shock metamorphism of carbonaceous chondrites abstract we have studied shock effects in carbonaceous chondrites using optical microscopy of thin sections and find that our petrographic classification of progressive shock metamorphism in ordinary chondrites can also be applied to carbonaceous chondrites we find that sixty nine carbonaceous chondrites can be assigned to four shock stages si to s4 largely on the basis of shock effects in olivine the least shocked chondrite groups are cm2 and co3 thirty six out of thirty eight members are classified as shock stage s1 differences between the mean shock levels of certain groups of chondrites e g co3 and cv3 are probably due to stochastic differences in the sampling of their parent bodies however there is an overall tendency for the mean shock level of carbonaceous chondrites and ordinary chondrites to increase with increasing petrologic type that may reflect real differences in the shock level of near surface materials on their parent bodies caused by intrinsic variations in the chemical and physical properties of these materials petrologic type 2 and 3 chondrites are more porous and richer in volatiles than types 4 to 6 the greater porosity of types 2 3 causes higher post shock temperatures and melting at lower pressures and the higher volatile contents ensure that strongly shocked material is more readily dispersed on release from high pressure we suggest that type 2 3 material shocked above 20 30 gpa normally escapes from the parent asteroids and forms particles that are too small to survive as meteorites in the cv3 group there is a correlation between the degree of chondrule flattening and the intensity of shock metamorphism analogous to that discovered in ordinary chondrites by sneyd et al 1988 suggesting that shock rather than static overburden pressure is responsible for chondrule flattening we infer that the correlations are due to collapse of pores under shock pressures of at least 5 10 gpa and that shock is an important process affecting many physical properties of type 2 4 chondrites

siderophile trace elements in metals and sulfides in enstatite achondrites record planetary differentiation in an enstatite chondritic parent body abstract siderophile element concentrations were measured by la icp ms in metals and sulfides from five aubrite meteorites siderophile element patterns in aubrites are either similar to those in metal from enstatite chondrites or can be derived by crystallization from metallic liquids derived by partial melting of e chondrites some metal grains in mt egerton cumberland falls and aubres show moderate to severe depletion in compatible highly siderophile elements re os ir ru which are consistent with solid metal liquid metal differentiation of enstatite chondrite like metal metals from chondrite inclusions in cumberland falls show more extremely fractionated patterns than those from the aubritic matrix potentially hinting at fractionation and partial melting processes affecting not only the aubrite parent body but the chondrite body from which the inclusions were derived as well models using experimental partition coefficients show that aubrite metal chemically corresponds to solid metal segregated during differentiation of primary metallic liquids of eh el composition that contained both substantial s and c contents this result is consistent with a genetic link between enstatite chondrites and aubrites but as to whether aubrites were derived from the same body ies as enstatite chondrites or have their origin in multiple and potentially separated bodies cannot be answered unequivocally with chemical or isotopic data alone

schoellhornite na sub 0 3 h 2 o 1 crs 2 a new mineral in the norton county enstatite achondrite

petrology of alh85085 a chondrite with unique characteristics abstract alh85085 has several characteristics which set it apart from any known chondritic group its chondrules are smaller 25 75 m the majority are cryptocrystalline and all are volatile na k s depleted feni metal is more abundant 40 9 wt than in any other chondrite and sulfide abundance is low 1 1 matrix material does not surround the chondrules and fragments but occurs as lithic clasts lumps up to 300 m across the bulk composition of alh85085 is lower in na si and s si and higher in ni si fe si and mg si than in other chondritic groups the ca si al si and mg si ratios are closest to those of the renazzo chondrite grouplet cr matrix lumps are most similar to cr and murchison group cm chondrite matrices survival of this fragile matrix material as lithic clasts indicates that they were added just prior to the agglomeration of the chondrite all components chondrules fragments matrix lumps fall within a narrow size range which may be the result of aerodynamic sorting if so the sorting must have occurred after chondrule solidification and following a period of chondrule breakage since fragments from larger chondrules are present the ni vs co trend in the feni metal overlaps that of metal in cr chondrites and bencubbin these trends are similar to those of calculated nebular condensation paths indicating a nebular origin the cryptocrystalline texture and volatile depletion of the chondrules indicate that most chondrules were heated to temperatures above the liquidus although alh85085 cannot now be assigned to any known chondrite group it shares many similarities with cr chondrites and the bencubbin metal silicate chondritic assemblage and may be part of a chondritic group closely related to these meteorites

the dynamics of boundary layer jets within the tropical cyclone core part ii nonlinear enhancement abstract observations of wind profiles within the tropical cyclone boundary layer until recently have been quite rare however the recent spate of observations from the gps dropsonde have confirmed that a low level wind speed maximum is a common feature of the tropical cyclone boundary layer in part i a mechanism for producing such a maximum was proposed whereby strong inward advection of angular momentum generates the supergradient flow the processes that maintain the necessary inflow against the outward acceleration due to gradient wind imbalance were identified as being i vertical diffusion ii vertical advection and iii horizontal advection and a linear analytical model of the boundary layer flow in a translating tropical cyclone was presented and used to diagnose the properties of the jet and the near surface flow a significant shortcoming was that the jet was too weak which was argued to be due to the neglect of vertical advection here a high resolution dry hydrostatic numerical

comments on symmetric and asymmetric structures of hurricane boundary layer in coupled atmosphere wave ocean models and observations abstract in a recent paper lee and chen 2012 hereafter lc12 presented numerical simulations of symmetric and asymmetric hurricane boundary layer structures in a fully coupled atmosphere wave ocean model and used these simulations to compare aspects of the boundary layer structure against an analysis of observations one of their main conclusions was that the azimuthally averaged inflow layer tends to misrepresent the overall inflow structure in tropical cyclones especially the asymmetric structure p 3593 another main conclusion was that the complicated asymmetric three dimensional boundary layer structures attributed by them to be due in part to the air sea and wind wave coupling make it difficult to parameterize the atmosphere wave ocean coupling effects without a fully coupled model p 3593 after careful examination of their study we have a number of questions regarding their methodology their interpretations including their interpretations of previous literature and their conclusions specifically we inquire about aspects of the methodology for defining the dynamical boundary layer depth the selection of the boundary layer scheme and we question the conclusions inferred in addition to the foregoing concerns inaccuracies in their literature review are noted and inconsistencies between their conclusions and reported results are identified for many decades physical processes across the air sea interface and within the atmospheric boundary layer have been known to be essential for the development and maintenance of a tropical cyclone ooyama 1969 emanuel 1986 1995 smith et al 2009 smith and montgomery 2010 bryan and rotunno 2009 bryan 2012 however the boundary layer is the least observed part of a storm in particular its turbulence structure with the advent of the global positioning system gps dropsonde hock and franklin 1999 the mean boundary layer structure has been progressively studied

observed boundary layer wind structure and balance in the hurricane core part i hurricane georges abstract the gps dropsonde allows observations at unprecedentedly high horizontal and vertical resolution and of very high accuracy within the tropical cyclone boundary layer these data are used to document the boundary layer wind field of the core of hurricane georges 1998 when it was close to its maximum intensity the spatial variability of the boundary layer wind structure is found to agree very well with the theoretical predictions in the works of kepert and wang in particular the ratio of the near surface wind speed to that above the boundary layer is found to increase inward toward the radius of maximum winds and to be larger to the left of the track than to the right while the low level wind maximum is both more marked and at lower altitude on the left of the storm track than on the right however the expected supergradient flow in the upper boundary layer is not found with the winds being diagnosed as close to gradient balance the tropical cyclone boundary layer model of kepert and wan

an antarctic iron meteorite contains preterrestrial impact produced diamond and lonsdaleite of the many meteorites recovered so far from the allan hills antarctica only nine have been irons one of these alha77283 contains troilite fes graphite c schreibersite fe ni 3p cohenite fe3c inclusions rich in the carbonado type diamond lonsdaleite nodules previously described from the canyon diablo meteorite1 2 the canyon diablo arizona meteorite the excavator of meteor crater is the only other iron meteorite known to contain these high pressure minerals and their occurrence in that meteorite has been explained as the result of shock induced transformation of graphite most probably at the moment of terrestrial impact and disintegration of the projectile during crater formation3 6 the suggestion7 that formation was by high gravitational pressure has not been accepted virtually identical diamond lonsdaleite containing material in alha77283 occurs in a meteorite specimen with a well developed heat altered zone produced by atmospheric ablation it seems therefore that the diamond and lonsdaleite were present in the meteoroid before its final ablative passage through the atmosphere and soft landing on the ground the shock event that produced these high pressure phases therefore must have taken place on its parent body or have been associated with the disruption of that body here we present the metallographic and x ray diffraction data on which this conclusion is based

response to comments of z j kabala and g sposito on the paper on the stochastic theory of solute transport by unsteady and steady groundwater flow in heterogeneous aquifers by m l kavvas and a karakas journal of hydrology vol 179 1996 321 351 abstract it is shown that the comment of kavvas and karakas j hydrol 179 321 351 1996 concerning the inapplicability of eqs a10 and 6 in kabala and sposito water resour res 27 341 350 1991 to transport by nonstationary flow is correct and that eqs a10 6 and 7 of kabala and sposito 1991 are incorrect for the transport case treated in that paper the correct expressions for eqs a10 and 6 in kabala and sposito 1991 are provided it is also shown that the claims of kabala and sposito 1998 concerning the theoretical developments in kavvas and karakas 1996 have no basis

the compositional classification of chondrites vii the r chondrite group bulk compositional and petrographic data clearly define the new r rumuruti group of chondrites consisting of rumuruti the only fall alh85151 acfer 217 carlisle lakes dar al gani 013 pca91002 pca91241 y 75302 y 793575 and y 82002 compositional petrographic rare gas and 0 isotopic data strongly suggest that pca91002 and pca91241 are paired the yamato specimens are probably not paired the matrices of the known r chondrites have experienced similar minor degrees of metamorphism petrographic types are 3 8 3 9 with the exception of alh85151 3 6 all except carlisle lakes contain equilibrated r5 r6 clasts petrographically the r chondrites are characterized by a low chondrule matrix modal abundance ratio high states of oxidation reflected by abundant nio bearing olivine with fa37 40 relatively small chondrules mean apparent diameters of 400 abundant up to 11 wt sulfides mainly pyrrhotite and pentlandite and negligible amounts of metallic fe ni refractory lithophile abundances are 0 95 x cl intermediate between those in ordinary chondrites oc and ci chondrites abundances of the volatile elements se and zn are greatly enhanced relative to oc the r chondrites are clearly distinguished from other chondrite groups on the basis of al mn and zn mn abundance ratios the oxygen isotopic data plot roughly along a slope 12 line with whole rock 17o values higher than for any other chondrite group rumuruti acfer 217 alh85151 pca91002 and pca91241 have light dark structures and solar wind implanted rare gases indicating that they are regolith breccias the yamato specimens also have light dark structures and are inferred to be regolith breccias carlisle lakes lacks solar rare gases and is unbrecciated based on similarities in refractory lithophile abundances 00 95 x ci oxygen isotope compositions 17o 0 and refractory inclusion abundances 0 1 vol none have been reported the r chondrites probably belong to a noncarbonaceous superclan of chondrites that also includes ordinary and enstatite chondrites the high oxidation state high matrix chondrule modal abundance ratio relatively low abundance of droplet chondrules and high 17o composition suggest that the r chondrites formed at greater heliocentric distances than the oc

carbonates in ci chondrites clues to parent body evolution all ci chondrites are regolith breccias consisting of various types of chemically and mineralogically distinct mineral and lithic fragments or units in the ci chondrite ivuna for example four different lithological units were identified and are referred to as lithology i ii iii and iv so far lithologies iii and iv have been identified in orgueil as well it appears that at least ivuna and orgueil consist of the same basic lithologies in different proportions carbonates in cis occur as individual grains within such lithic units or exist as large fragments between them carbonate fragments are remnants of former carbonate veins and in contrast to individual carbonate grains are not genetically linked to lithological units four different types of carbonates dolomite breunnerite calcite siderite occur in cis and they constitute on average 5 vol of each studied section in this study carbonates in the ci chondrites orgueil ivuna alais and tonk were studied petrographically mineralologically and chemically the results clearly indicate that in contrast to most previous studies compositional differences exist between dolomites within and among ci chondrites from these differences it can be derived that 1 several episodes of alteration occurred on the ci parent body 2 physicochemical conditions during carbonate formation must have been different among cis and 3 ci carbonates obviously were formed at low temperatures in equilibrium with surrounding fluid s while local compositional changes in fluid s on a micrometer to millimeter scale as reflected by dolomite compositions within ci chondrites were most likely controlled by the availability of ca2 mg2 fe2 and especially mn2 ions in the aqueous solutions more widespread compositional changes on a meter or even larger scale were controlled by variable ph eh co2 partial pressure and especially temperature conditions as reflected by the compositional variability of dolomites among cis

the semarkona meteorite first recorded occurrence of smectite in an ordinary chondrite and its implications abstract semarkona is an unshocked unequilibrated ordinary chondrite much of the interchondrule matrix and the mesostases of some chondrules and clasts have been hydrothermally altered analyses of altered materials and opaque matrix are presented ca and fe have been redistributed from primary anhydrous phases into calcite and na fe smectite respectively in semarkona the process possibly requires open system behavior inconsistent with the conventional view of metamorphism of the ordinary chondrites the low petrologic type previously assigned to semarkona is the result of retrograde metamorphism under aqueous conditions of a higher temperature mineral assemblage semarkona and possibly bishunpur should be assigned to petrologic type 2

an air sea interaction theory for tropical cyclones part ii evolutionary study using a nonhydrostatic axisymmetric numerical model abstract in part i of this study an analytical model for a steady state tropical cyclone is constructed on the assumption that boundary layer air parcels are conditionally neutral to displacements along the angular momentum surfaces of the hurricane vortex the reversible thermodynamics implied by this assumption allows the mature storm to be thought of as a simple carnot engine acquiring heat at the high temperature ocean surface and losing heat near the low temperature tropopause although the oceanic heat source is universally recognized as the sine qua non for the mature hurricane there is also wide acceptance of conditional instability of the second kind cisk which makes no specific reference to surface heat fluxes as the formative mechanism this ambivalence is seen in that all numerical simulation studies find it essential to have transfer from the ocean surface yet all start from a conditionally unstable atmosphere the hypothesis put forward in part i based on the steady state theory is t

technical comment on on the stochastic theory of solute transport by unsteady and steady groundwater flow in heterogeneous aquifers by m l kavvas and a karakas journal of hydrology vol 179 1996 321 351 abstract in this note we demonstrate that statements made in a recent paper by kavvas and karakas 1996 j hydrol 179 321 351 concerning the assumptions underlying the stochastic model of solute transport in spatially heterogeneous aquifers developed by kabala and sposito 1991 water resour res 25 341 350 are incorrect