a cool anomaly off northern california an investigation using ir imagery and in situ data satellite ir imagery and in situ hydrographie data are used to understand better the mesoscale variability of the california current system and to explore the relation of its surface and subsurface thermal structures in august 1982 one of the cool filaments commonly seen in satellite ir images during summer off northern california was sampled hydrographically during an optoma ocean prediction through observation modeling and analysis cruise based on the cool anomaly seen in a series of ir images and the in situ hydrographie data and based on geostrophic calculations a jet entrained upwelled coastal water and advected it rapidly through the warmer waters offshore providing an important cross shore transfer process the anomaly was about 50 km wide and extended vertically to about 40 m the temperature patterns at the surface were well correlated with those to about 30 m below 50 m the surface temperature was better correlated with horizontal temperature gradients i e the thermal wind consistent with strong horizontal advection by the geostrophic jet the cool anomaly was also relatively dense based on investigation of the t s properties the coastal water had been diluted through mixing with columbia river plume water on the northern edge of the anomaly near the temperature front in the shoreward sampled portion of the anomaly and just south of the anomaly interleaving occurred there was also a surface saline anomaly embedded in the cool anomaly near the temperature front the location of the temperature front in the in situ data and in the ir imagery corresponded well the temperature front was tracked in a series of ir images over 2 weeks the reorientation of the seaward extremity of the anomaly from westward to northwestward and the southwestward displacement of its southern boundary at speeds of 2 to 5 km d were consistent with the propagation of mesoscale features evident in successive quasi synoptic surface dynamic topography maps the southwestward displacement was probably also related to surface ekman transport

recharge processes on typical karst slopes implied by isotopic and hydrochemical indexes in xiaoyan cave guilin china summary measurements of the hydrogen and oxygen isotopic composition of precipitation and drip stream water at drip site xy5 in xiaoyan cave in guilin city were conducted to investigate the infiltration and vadose flow processes and to characterize precipitation discharge relationship in the overlying karst hillslope area a marked seasonal variability of oxygen and hydrogen isotopes was observed in precipitation ranging from 18 7 to 0 6 for 18 o and 139 to 5 for d respectively during the study period from november 2013 to october 2014 however the narrow range observed for cave drip stream water d of 43 to 22 18 o of 7 3 to 4 3 was attributed to homogenization via mixing of meteoric waters in the unsaturated zone above the cave although drip stream waters plot close to or slightly above the local meteoric water line the weighted average 18 o value of precipitation is depleted than in dripwater which is attributed to evaporation predominantly in the rainy season when cave air circulation is most active the relationship between surface infiltration or leakage and cave discharge is connected by the distinct models of flow through the epikarst zone vadose flow showed high peaking hydraulic responses but buffered rain isotope responses with an attenuate magnitude of 5 0 9 4 for 18 o the sudden hydrochemical proxy variability was related closely to increase of discharge and the flushing out of old water with higher dissolved calcite a threshold of flow generation expressed by precipitation amount must be exceeded to create a peak in discharge as a function of excessing the field capacity of soil and residual capacity of epikarst zone the sources of vadose seepage are soil and epikarst reservoir water with the attenuation of the isotopic fluctuations 4 28 to 5 92 for 18 o and slight hydrological response indicating mixed signals of infiltration water in epikarst storage reservoir the total discharge volume of percolating water is 2084 l derived from piston flow due to the increased hydraulic head in the dry season which provides a quantitative evidence of the potential adaptive capacity of the system to deal with the extreme droughts

wind driven circulation in a shelf valley part i mechanism of the asymmetrical response to along shelf winds in opposite directions abstractmotivated by observations in hudson shelf valley showing stronger onshore than offshore flows this study investigates wind driven flows in idealized shallow shelf valleys this first part of a two part sequence focuses on the mechanism of the asymmetrical flow response in a valley to along shelf winds of opposite directions model simulations show that i when the wind is in the opposite direction to coastal trapped wave ctw phase propagation the shelf flow turns onshore in the valley and generates strong up valley transport and a standing meander on the upstream side in the sense of ctw phase propagation of the valley and ii when the wind is in the same direction as ctw phase propagation the flow forms a symmetric onshore detour pattern over the valley with negligible down valley transport comparison of the modeled upstream meanders in the first scenario with ctw characteristics confirms that the up valley flow results from ctws being arrested by the wind driven shelf flow establishin

wind forced modeling studies of currents meanders and eddies in the california current system this process oriented study of the california current system ccs uses a high resolution multilevel primitive equation ocean model on a plane to isolate the response of that eastern boundary oceanic regime to temporal and spatially varying wind forcing to study the generation evolution and maintenance of many of the observed features such as currents meanders and eddies in the ccs the model is forced from rest with seasonal climatological winds in response to the prevailing wind direction surface equatorward currents develop along with upwelling of cooler water along the coast and a poleward undercurrent baroclinic barotropic instabilities in the equatorward surface current and poleward undercurrent result in the generation of meanders near the coast as the meanders intensify cold upwelling filaments develop along the coast and subsequently extend farther offshore in time the meanders form both cyclonic and anticyclonic eddies which subsequently propagate farther offshore longer simulation times 3 4 years in which a quasi equilibrium state for the ccs is reached show a seasonal cycle in response to the wind forcing for the coastal currents upwelling and filaments the meanders and eddies however can be quasi permanent as well as seasonal features the quasi permanent features play a significant role in modifying coastal currents upwelling and filaments which leads to large temporal and spatial variability in the ccs in a sensitivity study the results from several numerical experiments are used to examine the dependence of the generation of the currents meanders and eddies on the type of coriolis parameterization wind forcing and coastline geometry both the meridional variability of plane and the alongshore component of the wind stress are shown to be key ingredients for generating realistic vertical and horizontal structures for the cores of the surface equatorward and the subsurface poleward currents with such structures the currents are baroclinically and barotropically unstable resulting in the generation of meanders filaments and eddies irregularities in the coastline geometry are shown to be important for anchoring upwelling and filaments as well as for enhancing the growth of meanders and eddies cyclonic eddies tend to form in the vicinity of capes while anticyclonic eddies tend to form in the coastal indentations between capes the region off cape blanco is identified as the location where the coastal equatorward flow off oregon leaves the coast to develop a meandering jet off california the results from these experiments support the hypothesis that wind forcing and coastline irregularities on a beta plane are important mechanisms for the generation of many of the observed features of the ccs

subsurface formation of oxidants on mars and implications for the preservation of organic biosignatures abstract hydrogen peroxide can form through the interaction of pyrite and anoxic water the oxidation of pyrite results in the precipitation of sulfates and iron oxides high redox potentials 1000 mv and acidic ph 3 4 the oxidative potential of the resultant solution may be responsible for the oxidation of organic compounds as observed in the subsurface of the rio tinto mars analog on mars subsurface migration of groundwater interacting with volcanogenic massive pyrite deposits would have mobilized acidic and oxidizing fluids through large portions of the crust resulting in the widespread deposition of sulfates and iron oxides this groundwater could have leached substantial volumes of aquifer material and crustal rocks thereby erasing any organic compounds possibly down to depths of hundreds of meters therefore the preservation of organic biosignatures must have been severely constrained in the portions of the ancient martian crust that were exposed to aqueous processes calling for a redefinition of the future targets in the search for biomolecular traces of life on mars

sources and physical processes responsible for oh h2o in the lunar soil as revealed by the moon mineralogy mapper m3 1 analysis of two absorption features near 3 m in the lunar reflectance spectrum observed by the orbiting m3 spectrometer and interpreted as being due to oh and h2o is presented and the results are used to discuss the processes producing these molecules this analysis focuses on the dependence of the absorptions on lunar physical properties including composition illumination latitude and temperature solar wind proton induced hydroxylation is proposed as the creation process and its products could be a source for other reported types of hydrogen rich material and water the irregular and damaged fine grained lunar soil seems especially adapted for trapping solar wind protons and forming oh owing to abundant dangling oxygen bonds the m3 data reveal that the strengths of the two absorptions are correlated and widespread and both are correlated with lunar composition but in different ways feldspathic material seems richer in oh these results seem to rule out water from the lunar interior and cometary infall as major sources there appear to be correlations of apparent band strengths with time of day and lighting conditions however thermal emission from the moon reduces the apparent strengths of the m3 absorptions and its removal is not yet completely successful further many of the lunar physical properties are themselves intercorrelated and so separating these dependencies on the absorptions is difficult due to the incomplete m3 data set this process should also operate on other airless silicate surfaces such as mercury and vesta which will be visited by the dawn spacecraft in mid 2011

production of reactive oxygen species from abraded silicates implications for the reactivity of the martian soil abstract the results of the labeled release and the gas exchange experiments conducted on mars by the viking landers show that compounds in the martian soil can cause oxidation of organics and a release of oxygen in the presence of water several sources have been proposed for the oxidizing compounds but none has been validated in situ and the cause of the observed oxidation has not been resolved in this study laboratory simulations of saltation were conducted to examine if and under which conditions wind abrasion of silicates a process that is common on the martian surface can give rise to oxidants in the form of hydrogen peroxide h 2 o 2 and hydroxyl radicals oh we found that silicate samples abraded in simulated martian atmospheres gave rise to a significant production of h 2 o 2 and oh upon contact with water our experiments demonstrated that abraded silicates could lead to a production of h 2 o 2 facilitated by atmospheric o 2 and inhibited by carbon dioxide furthermore during simulated saltation the silicate particles became triboelectrically charged and at pressures similar to the martian surface pressure we observed glow discharges electrical discharges can cause dissociation of co 2 and through subsequent reactions lead to a production of h 2 o 2 these results indicate that the reactions linked to electrical discharges are the dominant source of h 2 o 2 during saltation of silicates in a simulated martian atmosphere given the low pressure and the relatively high concentration of co 2 our experiments provide evidence that wind driven abrasion could enhance the reactivity of the martian soil and thereby could have contributed to the oxidation of organic compounds and the o 2 release observed in the labeled release and the gas exchange experiments furthermore the release of h 2 o 2 and oh from abraded silicates could have a negative effect on the persistence of organic compounds in the martian soil and the habitability of the martian surface

nanophase iron enhanced chemical reactivity of ground lunar soil abstract the plan to resume robotic and manned missions to the moon in the next decade has led to a renewed interest in the properties of lunar soils ranging from geological to chemical to toxicological as an approximation of the effects of crushing and weathering on the moon previous work w t wallace et al 2009 meteor planet sci 44 961 970 demonstrated that freshly ground lunar soil is extremely active as measured by the production of hydroxyl radicals in solution the present study was performed in order to understand the origin of this reactivity we have ground 8 lunar soils of varying maturity and source highland or mare and measured the hydroxyl radical production and decay of the reactivity it was determined that there is a direct correlation between the reactivity and the amount of nanophase metallic iron particles as a function of soil maturity in the samples thus the highland soils with their lower total feo contents and less nanophase iron are less reactive than ground mare soils however there was no obvious correlation between maturity and source highland or mare with respect to the amount of time required for deactivation to a non reactive state these results provide the first chemical reactivity values as an important property of lunar soils necessary data for returning humans to the moon

a laboratory model of thermocline depth and exchange fluxes across circumpolar fronts a laboratory experiment has been constructed to investigate the possibility that the equilibrium depth of a circumpolar front is set by a balance between the rate at which potential energy is created by mechanical and buoyancy forcing and the rate at which it is released by eddies in a rotating cylindrical tank the combined action of mechanical and buoyancy forcing builds a stratification creating a large scale front at equilibrium the depth of penetration and strength of the current are then determined by the balance between eddy transport and sources and sinks associated with imposed patterns of ekman pumping and buoyancy fluxes it is found that the depth of penetration and transport of the front scale like l and wel2 respectively where fw g9 e we is the ekman pumping g9 is the reduced gravity across the front f is the coriolis parameter and l is the width scale of the front last the implications of this study for understanding those processes that set the stratification and transport of the antarctic circumpolar current acc are discussed if the laboratory results scale up to the acc they suggest a maximum thermocline depth of approximately h 5 2 km a zonal current velocity of 4 6 cm s 21 and a transport t 5 150 sv 1 sv 106 m3 s 21 not dissimilar to what is observed

the role of nearshore slope on cross shore surface transport during a coastal upwelling event in gulf of finland baltic sea abstract the wind induced coastal upwelling process often contains a mid phase that involves coherent long living cross shore surface jets of cooler water these jets extend to 40 45 km from the coast and tend to start from particular coastal locations we develop a simple method for evaluating the depth in the water column from where the upwelled water originates we also test the hypothesis that the development of cross shore surface jets may be triggered by some permanent characteristics such as the bathymetry or the slope of the nearshore seabed the analysis is performed for a strong and well documented upwelling in the gulf of finland the baltic sea using high resolution bathymetry data satellite derived sea surface temperature surface currents measured by in situ drifters and properties of water masses in two sampling locations the results indicate that the cross shore jets originate exclusively from the shore sections with much steeper slopes 0 0075 than in the rest of the study area the cooler water most likely origins from intermediate water masses at depths between 15 and 30 m the resulting identification of the source depth of the upwelled water and its spatial location assists in understanding the flux of nutrients during upwelling events and their link to the onset of cyanobacteria blooms

oxidation of water to hydrogen peroxide at the rock water interface due to stress activated electric currents in rocks common igneous and high grade metamorphic rocks contain dormant defects which release electronic charge carriers when stressed rocks thereby behave like a battery the charge carriers of interest are defect electrons h e g electronic states associated with o in a matrix of o2 known as positive holes or pholes for short the h travel along stress gradients over distances on the order of meters in the laboratory and kilometers in the field at rock water interfaces the h turn into o radicals e g highly reactive oxygen species which oxidize h2o to h2o2 for every two h charge carriers one h2o2 molecule is formed in the laboratory the battery circuit is closed by running a cu wire from the stressed to the unstressed rock in the field closure of the circuit may be provided through the electrolytical conductivity of water the discovery of h charge carriers their stress activation and their effect on earth s surface environment may help better understand the oxidation of the early earth and the evolution of early life

δ18o characteristics of meteoric precipitation and its water vapor sources in the guilin area of china the stable isotopic composition of meteoric precipitation is an important component of global and regional water cycle research stable isotope data can help reconstruct paleoclimate related to ice cores lake sediments and stalagmites we investigated the daily variation in isotopic composition of meteoric precipitation from 2008 to 2012 in the guilin region of china 18o of meteoric precipitation ranged from 14 21 to 2 38 with an average value of 5 78 vienna standard mean ocean water vsmow meteoric precipitation in the summer half year may through october increased with a relatively low 18o value of 8 04 vsmow average of 261 groups and 56 03 vsmow of average d accounting for 67 6 of the total annual meteoric precipitation meteoric precipitation in the winter half year november through april decreased with a relatively high 18o value of 2 89 average of 210 groups and 9 23 of average d accounting for 32 4 of total meteoric precipitation the local meteoric water line lmwl equation in guilin area has local climate characteristics by combining environmental isotope data of precipitation using a backwards trajectory water vapor sources of the meteoric precipitation in guilin area are inferred and traced our results show that the isotopic composition of meteoric water vapor sources in guilin area are related to monsoon type source of precipitation cloud masses and precipitation properties the isotopic composition of meteoric precipitation in the summer half year may through october was mainly affected by the summer monsoon or summer typhoons namely controlled by water vapor source from the bay of bengal and the south china sea and the second the west pacific and the 18o value of meteoric precipitation was strongly negative there was a significant negative correlation between the 18o values of meteoric precipitation and the amount of precipitation and temperature in the summer half year the amount effect of the meteoric precipitation often concealed the temperature effect the isotopic composition of meteoric precipitation in the winter season or winter half year was affected by the water vapor source of the warm moist air masses from the west pacific and continental cold air masses from the siberia mongolia winter monsoon or local evaporation vapor circulation and the 18o value of meteoric precipitation was relatively positive and indicated that the water vapor of meteoric precipitation along the water vapor trajectory was affected by the evaporation as well as the local water vapor evaporation the research results have showed that different sources of water vapor has a significant influence on the 18o variation of meteoric precipitation therefore analysis of 18o in the meteoric precipitation especially its seasonal variation characteristics of analysis can conversely reveal the water vapor sources of local meteoric precipitation

atmospheric imaging results from the mars exploration rovers spirit and opportunity a visible atmospheric optical depth of 0 9 was measured by the spirit rover at gusev crater and by the opportunity rover at meridiani planum optical depth decreased by about 0 6 to 0 7 per sol through both 90 sol primary missions the vertical distribution of atmospheric dust at gusev crater was consistent with uniform mixing with a measured scale height of 11 56 0 62 kilometers the dust s cross section weighted mean radius was 1 47 0 21 micrometers mm at gusev and 1 52 0 18 mm at meridiani comparison of visible optical depths with 9 mm optical depths shows a visible to infrared optical depth ratio of 2 0 0 2 for comparison with previous monitoring of infrared optical depths

stable isotope ratios in precipitation and their relationship with meteorological conditions in the kumaon himalayas india summary for the first time environmental isotopic 2h 18o 3h data predominantly based on precipitation samples in the kumaon himalayas india have been used to understand the influence of various meteorological factors governing rainout processes in the region further the data are also used to understand the orographic effects in precipitation and to estimate the altitude effect in stable isotopic ratios in precipitation etc the interpretation of the isotopic data revealed that the source of moisture for winter october february and summer may precipitation in the kumaon himalayas is mainly from the western disturbances whereas for the remaining period the source is monsoonal southwest the 2 18o relationship in the local precipitation during the monsoon season shows a distinct seasonal effect with a slope of 7 6 the winter and summer precipitation samples measured higher environmental 3h compared to southwest monsoon samples thus indicating continental evaporated moisture there is wide range of altitude effects 18o variation per 100 m elevation 0 30 july august 0 57 september with the mean altitude effect being 2 61 and 0 36 per 100 m elevation for 2h and 18o respectively these values are different from that reported earlier for the region based on the isotopic compositions of springs rivers samples the altitude effect in successive precipitation is basically a temperature dependent phenomenon and is explained on the basis of adiabatic cooling related rainout process dry adiabatic lapse rate moist adiabatic lapse rate and saturated adiabatic lapse rate for moist air mass the altitude effect is found to be more reliable in case of 2 as deuterium is least affected by secondary evaporation the effect of secondary evaporation has been observed on the true altitude effect secondary evaporation of rainfall increases the oxygen isotopic ratios and the increase is directly proportional to the vertical distance travelled by the raindrops through air

chemical signature detection of groundwater and geothermal waters for evidence of crustal deformation along fault zones abstract common crustal igneous and high grade metamorphic rocks contain peroxy defects which remain dormant until the rock experiences stress upon deformation stress activated peroxy defects form highly reactive oxygen species ros at the rock water interface observed in both terrestrial and extraterrestrial rock samples the ros complex is formed upon rock fluid interaction when groundwater combines with the ros to produce hydrogen peroxide giving an indirect measure of the underlying rock stress and crustal deformation along active faults the average concentration of hydrogen peroxide from the sohna thermal spring water falling along the active sohna fault and geothermal field was measured to be 0 53 0 014 mg l similar average concentration was also recorded from borewell sample north of the spring 0 56 0 017 mg l within the same geothermal field lower concentration of hydrogen peroxide was recorded within samples collected from hard rock aquifers outside the geothermal field and the active fault zone 0 138 0 095 mg l the detailed analysis suggests that the presence of hydrogen peroxide is largely dependent on the circulation pattern through the interconnected fractures joints within the quartzite bedrock lying adjacent to the fault plane laboratory analysis results also show high hydrogen peroxide concentration within two borewell samples falling adjacent to the epicentre of a shallow microtremor event within the hard rock region falling alongside a lineament along the delhi hard rock mega fold rock water interaction post stress activation of peroxy defects and formation of ros has therefore been inferred to be responsible for the formation of hydrogen peroxide at the rock water interface within these zones this pilot study provides scientific field evidence that hydrogen peroxide concentrations within groundwaters might offer prospects for seismic stress estimation and crustal deformation along seismically active zones

evaluating the role of sulfide weathering in the formation of sulfates or carbonates on mars orbital and landed missions to mars have revealed complex sulfate and fe oxide bearing mineralogical assemblages which have been interpreted as the result of a late planet wide acidic period due to large so2 emissions however this global scenario does not explain the recent discovery of hesperian and noachian aged carbonates in several regions because they should have been dissolved by the acidic conditions nor the restriction of sulfate occurrences in preferential regions here we present the results of a 4 year long experimental study designed to test the impact of fe sulfides pyrrhotite fe0 9s on the weathering of basaltic silicates olivine clino and orthopyroxene under an early martian like co2 rich atmosphere our weathered silicate sulfide mixtures showed complex parageneses containing elemental sulfur hydrated sulfates gypsum hexahydrite jarosite and fe oxy hydroxides olivine only samples produced nesquehonite an mg carbonate precursor of hydromagnesite and magnesite these secondary phases are similar to those observed in the martian sulfate and carbonate bearing deposits therefore we propose a geochemical model in which on the one hand martian sulfates mainly formed from weathering of sulfide enriched basalts producing locally acidic environments and on the other hand carbonates were preserved and could even have formed in regions initially devoid of sulfides thereby resolving the apparent paradox arising from the possible coeval formation of the two types of minerals these results raise doubts on the need for a global acidic event to produce the sulfate bearing assemblages suggest that regional sequestration of sulfate deposits is due to regional differences in sulfide content of the bedrock and pave the way for reevaluating the likelihood that early sediments preserved biosignatures from the earliest times

an offshore eddy in the california current system part i interior dynamics abstract from january 9 to 17 1981 detailed observations of the horizontal and vertical structure beneath one of the quasi permanent semi stationary mesoscale offshore eddy signatures in the california current system ccs discussed by bernstein breaker and whritner 1977 burkov and pavlova 1980 and simpson 1982 were made the vertical sections of temperature and density show the presence of three layer system a subsurface warm core eddy whose diameter is about 150 km at the 7 c isotherm is the dominant feature a warm surface layer which extends to a depth of 75 m lies over the eddy between the warm surface layer and the subsurface warm core eddy there is a cold core region which extends to a depth of about 200 m there is a high degree of symmetry about the vertical axis of rotation vertical sections of salinity and dissolved oxygen are entirely different from sections of temperature and density diagrams of water mass characteristics confirm that the core of the eddy found between 250 600 m consists of inshore water from the california undercurrent cu below about 700 m local waters from the deep poleward flow dpf have been incorporated into the eddy the observed distributions of properties t s o 2 are inconsistent with a single local generation process for the eddy system radial distributions of angular velocity normalized gradient velocity and relative vorticity support the use of a gaussian radial height field as an initial condition in eddy models possible reasons why ccs eddies may differ dynamically from gulf stream rings are given in the text at the time the observations were made the system as a whole was in near geostrophic balance local geostrophic balance however cannot explain the observed distribution of properties and structure the observed symmetry in the structure of the eddy system chemical evidence simpson 1984 biological distributions haury 1984 and satellite images of the cc koblinsky simpson and dickey 1984 suggest that lateral entrainment of warm oceanic and cold coastal water into the upper two layers of the three layer system by the subsurface eddy is a likely generation mechanism for the cold core region the coastal origin of the frontal structure along the northeastern quadrant and the oceanic origin of the frontal structure along the southwestern quadrant of the eddy system further support lateral entrainment as a generation mechanism for the cold core this entrainment makes the ccs eddy system different from cold core rings in the gulf stream and rather similar to some warm core eddies found in the east australian current the presence of cu water in the core of this eddy raises the question of how cu water was transported from the continental slope eddy generation mechanisms other than baroclinic instability of the cc may be required to explain the distribution persistence and core composition of offshore mesoscale eddies in the ccs there is evidence that barotropic in addition to baroclinic processes may be important

satellite observations and modeling of meanders in the california current system off oregon and northern california abstract infrared satellite images from the west coasts of oregon and northern california are used to identify meander patterns in sea surface temperature which appear as large cold tongues extending offshore two relatively long series of images from 1982 and a few examples from 1980 and 1983 demonstrate the evolution of the cold tongues from an initial variety of scales 60 200 km to the fastest growing waves 110 130 km and then finally to tongues with longer wavelengths 400 km this is observed to occur over periods of about three months in summer and fall when the coastal circulation is composed of a southward surface current over a northward undercurrent the initial shorter scale features are believed to be excited by the interaction between the mean current and the coastal topography baroclinic instability associated with the vertical shear between the surface current and the undercurrent is found to be responsible for the growth of the features observed in the satellite imagery a nonlinear

possible sources driving the potential vorticity structure and long wave instability of coastal upwelling and downwelling currents it is well known that upwelling and downwelling currents are unstable to perturbations less is however known about the physical mechanism responsible for the observed and modeled instabilities it is shown that the origin of the long wave barotropic baroclinic instability observed on upwelling currents has to be sought among diabatic or thermobaric mechanisms in particular the role of mixing associated with kelvin helmholtz instability and of wind forcing is investigated low richardson numbers occur when the pycnocline outcrops at the sea surface the criterion for instability ri 1 4 can be reached in a narrow region close to the upwelling front permitting kelvin helmholtz instability and mixing this can precondition the current for long wave instability by transforming the current s potential vorticity a constant wind can likewise modify the potential vorticity the resulting potential vorticity anomaly is always negative for both upwelling and downwelling currents and this anomaly interacts with the outcropped front destabilizing it examples are provided via numerical calculations using an idealized front a wind stress is an effective means of inducing the negative pv necessary for instability with wind kelvin helmholz instability when present merely modifies the instability characteristics in addition upwelling fronts are always less stable than comparable downwelling fronts

acidic weathering of basalt and basaltic glass 1 near infrared spectra thermal infrared spectra and implications for mars engineering research council of canada the canadian space agency the canada foundation for innovation the manitoba research innovations fund and the university of winnipeg for supporting the establishment and operation of the planetary spectrophotometer facility this work was funded in part by the nasa 2001 mars odyssey themis project jet propulsion laboratory contract 1228404 through arizona state university and by the arizona state university exploration postdoctoral fellowship

coastal upwelling in the california current system abstract coastal upwelling in the california current system has been the subject of large scale studies off california and baja california and of small scale studies off oregon recent studies of the winds along the entire coast from 25 n to 50 n indicate that there are significant along shore variations in the strength of coastal upwelling which are reflected in the observed temperature distribution active upwelling appears to be restricted to a narrow coastal band about 10 25 km wide along the entire coast but the region influenced by coastal upwelling may be much wider intensive observations of the upwelling zone during summer off oregon show the presence of a southward coastal jet at the surface a mean vertical shear a poleward undercurrent along the bottom and persistently sloping isopycnals over the continental shelf most of the upwelling there occurs during relatively short periods several days long of upwelling favorable winds during the upwelling season off oregon the offshore ekman transport is carried by the surface ekman layer and the onshore return flow occurs through a quasi geostrophic interior it is not known whether the structure and dynamics observed off oregon are typical of the upwelling zone along the entire coast though some of the same features have been observed off baja california current and future research will eventually show whether the oregon results are also applicable in the region of persistently strong upwelling favorable winds off northern california and in the region of complex bathymetry off central and southern california

mesoscale to submesoscale transition in the california current system part ii frontal processes this is the second of three papers investigating the regime transition that occurs in numerical simulations for an idealized equilibrium subtropical eastern boundary upwelling current system similar to the california current the emergent upper ocean submesoscale fronts are analyzed from phenomenological and dynamical perspectives using a combination of composite averaging and separation of distinctive subregions of the flow the initiating dynamical process for the transition is near surface frontogenesis the frontal behavior is similar to both observed meteorological surface fronts and solutions of the approximate dynamical model called surface dynamics i e uniform interior potential vorticity q and diagnostic force balance in the intensification of surface density gradients and secondary circulations in response to a mesoscale strain field however there are significant behavioral differences compared to the surface dynamics model wind stress acts on fronts through nonlinear ekman transport and creation and destruction of potential vorticity the strain induced frontogenesis is disrupted by vigorous submesoscale frontal instabilities that in turn lead to secondary frontogenesis events submesoscale vortices and excitation of even smaller scale flows intermittent submesoscale breakdown of geostrophic and gradient wind force balance occurs during the intense frontogenesis and frontal instability events

numerical simulation of coastal upwelling and inerfacial instability of a rotaion and stratified fluid the evolution of the coastal upwelling and interfacial instability of a stratified and rotating fluid is studied numerically by using large eddy simulation upwelling is generated near the sidewall of a rotating annulus by the shear at the top the fluid initially consists of a stably stratified two layer structure with a narrow interface separating the two layers the large scale motion of the flow is simulated by solving the time dependent non hydrostatic incompressible navier stokes and scalar transport equations while the small scale motion is represented by a dynamic subgrid scale model the upwelling process contains both stable and unstable stratification the vertical structure of upwelling consists of a persistent primary front a trailing mixing zone on the shore side of the front and a temporary secondary front which leads a top inversion layer the longshore velocity profile has two maxima which occur at the edge of the sidewall boundary layer and at the density front the upwelled density front is unstable to azimuthal perturbations and baroclinic waves develop and grow to large amplitude pairs of cyclonic and anticyclonic waves appear at the front which form jet streams the secondary front is unstable to azimuthal perturbations its instability and the associated drop of the top inversion layer take the form of radial bands which subsequently break up into isolated patches and eventually sink the computed values of various upwelling time and length scales are compared to and are in good agreement with past experimental data

production of hydrogen peroxide in martian and lunar soils freshly ground basaltic minerals produce sufficient quantities of hydrogen peroxide h2o2 when immersed in solution to explain the oxidizing characteristics of martian soil samples collected by the viking landers h2o2 production occurs as a result of reactions between water and defects at the surface of mechanically pulverized minerals analogous to carcinogenic quartz dusts our results also indicate that dehydroxylation of mineral surfaces results in increased h2o2 production a highly relevant finding for dusts on the airless surface of the moon reactive pulverized minerals are important on planetary bodies where impact processes have generated fine grained basaltic dusts and may pose a significant health risk to astronauts visiting planetary surfaces where impacts have generated such materials

the hydrogen and oxygen isotopic composition of precipitation evaporated mine water and river water in montana usa summary the isotopic composition of 42 samples of rain and snow collected in 2004 were used to construct a local meteoric water line lmwl for butte montana the derived equation d 7 31 18 o 7 5 r 2 0 987 represents one of the first published lmwls based on direct precipitation for any location in the northern rocky mountains samples of underground and surface mine waters in butte including the berkeley pit lake and a nearby tailings pond define a linear trend with a much lower slope and intercept than the lmwl d 5 00 18 o 49 5 r 2 0 991 consistent with non equilibrium evaporation at an average relative humidity of roughly 65 detailed evaporation calculations are presented which indicate that the shallow berkeley pit lake was approximately 25 evaporated in october 2003 whereas the surface of the tailings pond was at least 50 evaporated the intersection of the lmwl and mine water evaporation trend was used to calculate the average composition of recharge water to the flooded mine complex d 139 18 o 18 0 these values are considerably lighter than the weighted total of precipitation for the 2004 calendar year d 118 18 o 15 3 which is partly explained by the unusually low snowfall that montana experienced in 2004 based on this study the lmwl recently proposed by kendall and coplen 2001 kendall c coplen t b 2001 distribution of oxygen 18 and deuterium in river waters across the united states hydrological processes 15 1363 1393 from regression of isotopic data from a number of montana rivers is more accurately interpreted as an evaporation line isotopic trends based on river data should be treated with caution particularly in a semi arid region such as montana where rivers are often influenced by dams and irrigation withdrawals

weathering of olivine under co2 atmosphere a martian perspective abstract recent analyses from the curiosity rover at yellowknife bay gale crater mars show sedimentary rocks deposited in a lacustrine environment and containing smectite clays thought to derive from the alteration of olivine however little is known about the weathering processes of olivine under early martian conditions and about the stability of smectite clays in particular here we present a 3 month experiment investigating the weathering of forsteritic olivine powders fo 90 under a dense co 2 atmosphere and under present day terrestrial conditions for comparison the experiment also evaluates the potential effects of hydrogen peroxide h 2 o 2 as a representation of the highly oxidizing compounds produced by photochemical reactions throughout martian history the weathered samples were characterized by means of near infrared spectroscopy nir x ray diffraction xrd transmission electron microscopy with energy dispersive x ray spectrometry tem edx mossbauer spectroscopy and thermogravimetry the results show that a mg rich smectite phase formed from the weathering of olivine under co 2 conditions although in lower abundance than under terrestrial conditions the main secondary phase formed under co 2 turns out to be a silica rich phase possibly acting as a passivating layer with a non diagnostic near infrared spectral signature the use of h 2 o 2 highlights the critical importance of both the redox conditions and fe content of the initial olivine on the nature of the secondary phases

a real time dynamical forecast of ocean synoptic mesoscale eddies energetic eddy currents are the oceanic analogue of atmospheric weather and have time scales of days to weeks and space scales of tens to hundreds of kilometres1 we have predicted their evolution in time by internal dynamical processes for the forecasts we transferred initialization data from ship to shore based computers during two 2 week periods in june and july of 1983 from an approximately 150 km 2 region in the deep north east pacific off california this is to the best of our knowledge the first such real time forecast at sea the results were substantially successful the dynamics predicted a prominent zonal jet absent in the initial flow also the model forecast revealed a strong eddy merger event otherwise obscured in the data prospects are encouraging for future forecasting which should have important implications for research and practical operations at sea2

reactive oxygen species at the oxide water interface formation mechanisms and implications for prebiotic chemistry and the origin of life the goal of our study is to identify free radical formation pathways on mineral surfaces organic molecules on early earth might have been modified or decomposed by such pathways thus affecting the total organic inventory for prebiotic synthesis reactions specifically we evaluated several common oxide minerals under a range of environmental conditions and combinations of conditions ph o2 level uv wavelength and particle loading for formation of highly reactive oxygen species ros at the oxide surfaces by quantifying the generated oh and h2o2 we identified anatase rutile tio2 tio2 and hematite fe2o3 as active in ros production and importantly found different dominant pathways for ros formation on anatase rutile versus hematite hydroxyl radicals oh in anatase and rutile suspensions were generated mainly through the oxidation of oh by photo generated holes and h2o2 was generated through the combination of an oh radical with an oh and a hole this pathway for the tio2 phases did not require the presence of o2 and was not shut down under anaerobic conditions in contrast formation of h2o2 and oh in hematite suspensions involved reduction of o2 by electrons which was inhibited under anaerobic conditions the surface ros as well as free radicals formed by reactions with other gases on early earth atmosphere were capable of destroying molecules such as lipids and pre rna or rna essential to assembly of protocells and survival of the earliest cells at the same time surface associated ros and other free radicals may also have promoted aminoamide formation thus the surface ros would have affected prebiotic organic compound inventory and protocell early life evolution

two layer model of shear driven coastal upwelling in the presence of bottom topography a stratified two layer fluid is brought to solid body counterclockwise rotation inside a cylindrical tank having a conical bottom with a radial topographic ridge a stress is then applied to the top surface by means of a clockwise differentially rotating disk the resulting ekman layer flux causes the top layer to spin down and the interface to rise near the wall and to descend a t the centre of the tank as this process continues the interface front between the two layers intersects the disk surface and after that migrates away from the wall and allows the bottom fluid to contact the disk directly the migration of the front continues until a steady state is reached the front becomes stationary and the system is in geostrophic balance the first sign of upwelled flow at the surface always occurs as a high speed jet like plume at the bottom topography and only at a later time does a uniform upwelled flow appear a t the surface upstream of the topography this plume which always forms near the downstream edge of the topography migrates in advance of the upstream front to produce an upwelling maximum at the bottom topography the final width of the upstream flow in steady state conditions is estimated by a simple theoretical model which is in good agreement with the experimental results we have an experimental criterion to predict the occurrence of travelling baroclinic waves on the upstream front on the downstream side of the ridge large standing waves are observed with significant upwelling within them under some circumstances cyclones pinch off from the upstream front the plume on the ridge and the crests of the large downstream standing waves we present criteria to predict the occurrence of these pinch off processes

basin scale wind forced dynamics of the seasonal southern south china sea gyre 1 using observed wind forcing the seasonal development and disappearance of the near surface anticyclonic gyre in the southern south china sea is modeled along with associated dynamic features forced by monsoon winds the ocean circulation in the south china sea alternates between a single cyclonic gyre during the winter northeast monsoon and a double gyre cyclonic anticyclonic in the northern southern south china sea during the summer southwest monsoon reversing the western boundary current along vietnam with each shift of the monsoon regime during the summer southwest monsoon the poleward western boundary current converges with the equatorward western boundary current of the northern gyre turning offshore to create an eastward jet and flanking dipole recirculation near 13 n the development and timing of the eastward jet and recirculations are consistent with large scale basin dynamics the subsequent transition to the winter northeast monsoon regime destroys the recirculation cells and eastward jet employing high resolution 1 5 layer and 2 0 layer numerical models we demonstrate the applicability of large scale dynamics to the deeper central basin of the south china sea specifically showing that the gyre scale circulation governs the development of the eastward jet and dipole recirculations the destruction of the recirculations by the monsoon winds each autumn is also modeled this effort highlights the dominance of monsoon wind forcing in the south china sea s basin scale dynamics

stable isotope evidence of dual arabian sea and bay of bengal vapour sources in monsoonal precipitation over north india abstract high resolution time series data of hydrogen d and oxygen 18o isotope values of precipitation have been generated for the first time at kolkata eastern india where the summer monsoon clouds from bay of bengal bob commence their journey over india use of a rayleigh cum two component mixing model and comparison of kolkata data with the international atomic energy agency iaea global network of isotopes in precipitation gnip data base of new delhi suggest that the precipitation at new delhi cannot be explained by simple continental effect of a bob vapour source alone traveling and raining successively along kolkata new delhi route it is necessary to invoke an admixture of 20 vapour originating from the arabian sea with the vapour coming from bob and finally causing summer monsoon rains at new delhi the findings have major implications to the regional water vapour budget over india

stable isotopic composition of precipitation in the semi arid north central portion of the us great plains abstract where data are available hydrologic studies may use stable oxygen and hydrogen isotopes to investigate groundwater surface water interaction groundwater recharge and advective diffusive transport to estimate groundwater ages or to unravel paleohydrology such studies require that the isotopic composition of precipitation be known as precipitation is a major input to groundwater and surface water systems oxygen 18 18 o and deuterium 2 h data for precipitation are lacking for the semi arid portion of the north central great plains of the us and thus there is need to establish additional meteoric water lines as isotope input functions across the region as well as to develop better understanding of the isotopic climate linkages that control oxygen and hydrogen isotope ratios in precipitation this study examines the 18 o and 2 h composition of precipitation for a representative site near north platte nebraska in the semi arid north central great plains during the years 1989 through 1994 oxygen 18 values range from 30 5 to 1 7 deuterium values range from 228 to 11 yearly arithmetic mean values for the north platte station are 9 8 and 71 respectively weighted yearly means for 18 o and 2 h over the 6 year period were 9 6 and 69 respectively north platte values show a strong isotopic enrichment between winter and summer precipitation and a strong 18 o t correlation r 2 0 845 for mean monthly values of 0 54 per degree celsius the local meteoric water line for the site is 2 h 7 66 18 o 4 96

selective withdrawal and spin up of a rotating stratified fluid we present an experimental study demonstrating that rotation has a pronounced effect on currents induced by selective withdrawal of fluid from a density stratified reservoir our observations show that initiating outflow from the reservoir generates kelvin shear waves these waves propagate cyclonically around the perimeter of the reservoir establishing an anticyclonic withdrawal layer flow this flow accelerates owing to the production of relative vorticity by compression of planetary vorticity the withdrawal layer thickness as shown by vertical profiles of the horizontal velocity grows with time separation of the side wall boundary layers in the corners of the tank causes the spun up flow to eventually break up into a series of counterrotating gyres we also present a model that describes many features of the spin up process observed before onset of separation and subsequent gyre formation the model shows that vertical diffusion of vorticity plays an important role in the spin up process leading us to conclude that apparent thickening of the withdrawal layer over time as seen in changes in the velocity profile is associated with the vertical diffusion of the spun up vorticity

regional scale climate influences on temporal variations of rainwater and cave dripwater oxygen isotopes in northern borneo this study investigates the relationship between large scale climate variability rainfall oxygen isotopic composition 18 o and cave dripwater 18 o at gunung mulu and gunung buda national parks in northern borneo 4 n 115 e on intraseasonal to interannual timescales a 3 yr timeseries of rainfall 18 o contains prominent seasonal and interannual variability the seasonal cycle in rainfall 18 o is defined by lighter values of 10 during late boreal summer and heavier values of 4 during late boreal winter and is poorly correlated to local precipitation which displays very weak seasonality seasonally varying moisture trajectories likely play a key role in the observed seasonal cycle of rainfall 18 o driving enhanced fractionation during boreal summer and less fractionation during boreal winter dripwater 18 o timeseries display 2 seasonal cycles that follow the rainfall 18 o seasonal cycles with a mean 18 o value equivalent to the mean 18 o of rainfall large surveys of cave dripwaters conducted during three fieldtrips to gunung mulu buda reveal a system wide response to rainfall 18 o seasonality that supports a relatively short less than 6months response time for most drips during the weak 2005 2006 la nina event sustained positive precipitation anomalies are associated with rainfall 18 o values that are 4 to 5 lighter than previous years values consistent with the tropical amount effect observed in both models and data dripwater 18 o values are 1 to 2 lighter during the weak la nina event the importance of the amount effect in driving intraseasonal rainfall 18 o anomalies at our site is supported by an 8 increase in rainfall 18 o that occurred over the course of two weeks in response to a pronounced decrease in regional convective activity dripwater discharge rates underwent a ten fold decrease during the extended dry period but dripwater 18 o values remained constant this study supports the interpretation of stalagmite 18 o records from gunung mulu buda as paleo precipitation records that are sensitive to the location and strength of deep convection in the west pacific warm pool 2007 elsevier b v all rights reserved

centennial scale monsoon climate fluctuations from a stalagmite record during the mid holocene epoch in fulu cave of huaping yunnan china the mid holocene dynamics of the east asian monsoon eam and indian monsoon im are important for understanding the holocene climate system to clarify the relationship between eam and im subsystems during the mid holocene a 2085 year 6 270 4 185 a bp high resolution record from stalagmite fl4 in yunnan china was reconstructed using icp ms 230th series dating and carbon and oxygen isotope analysis 13c and 18o in the study period successive positive 18o trends revealed a generally weakening asian monsoon with the monsoon climate tending toward gradual drying especially during three centennial scale drought events in 6 270 6 126 a bp 5 347 5 140 a bp and 4 810 4 620 a bp on the other hand the uninterrupted negative trend in 13c signified natural improvements in vegetation overlying the cave and a serious deficit 2 5 in 13c during 5 519 5 345 a bp implied a heavy rainfall event in precise phase with 18o demonstrating an enhanced indian monsoon subsystem the dense sawtooth shaped pattern of the carbon and oxygen isotope records indicates that a series of decadal scale abrupt climate changes were superimposed on the centennial scale monsoon climate changes fl4 stalagmite records in the mid holocene reflect a gradually weakening monsoon climate with superimposed decadal centennial events but natural improvements in local vegetation through self adjustment

characteristics of soil water movement in a grass slope in a karst peak cluster region china soil water is very important in hilly areas with thin soil layers and deep groundwater tables such as the karst peak cluster region of southwest china an investigation into soil water movement can provide insights into management of shallow water resources and soil nutrients as well as prevention of groundwater pollution in this study o 18 and h 2 tracers were used to trace soil water movement in planar soil mass type microhabitats in the middle part of a steep hillslope covered by grasses in a karst peak cluster region of china from may 2008 to july 2009 samples of precipitation and two types of soil water which had different integrated degrees of mobility and were of different depth intervals or depths were collected the hydrogeochemical characteristics were compared between precipitation and soil water and these data were applied in convolution based lumped parameter models our results indicated that vertical piston flow rather than lateral flow along the soil bedrock interface played an important role in soil water percolation at least in the upper soil layer approximately 7cm over the permeable bedrock the mixing effect and preferential flow might also play a role in soil water percolation in general the evaporation effect on soil water was weak except for the uppermost 10cm soil matrix water during winter the lower limits of mean transit time of soil matrix flow passing through 5 15 25 35 and 41 5cm depths were 4 81 7 70 16 19 21 85 and 27 44days respectively our study demonstrated the crucial functions of the soil reservoir in regulating the water cycle and could provide guidance on conservation of soil water and hydrological studies the applied method was proved to be a suitable approach for investigating soil water movement on a monthly scale

modeling the martian seasonal water cycle ever since the observations of percival lowell the annual cycle of martian water has been a fascinating topic in planetary exploration observations by the viking orbiter supplemented by earth based microwave and infrared observations have given us a reasonable picture of this cycle we are now also able to model the cycle using our mars climate model a simplified atmospheric general circulation model designed specifically for this purpose we find that a thin adsorbing layer of the martian regolith plays a fundamental role in the water cycle limiting the lower atmospheric relative humidity and preventing the formation of widespread ice deposits at low latitudes we are thus able to estimate a large scale average value of the specific soil surface area of this regolith water which evaporates from the permanent north polar ice cap during summer is returned by a process of repeated evaporation and precipitation on the retreating seasonal cap the following spring so that the global inventory of water outside the polar caps ranges within narrow limits there is a small net annual deposition of water ice at the south polar cap which is always at dry ice temperatures if ice on the residual south polar cap is exposed during the summer it rapidly sublimes generating vapor amounts similar to those observed in northern summer recovery to normal dry conditions in the southern atmosphere occurs very rapidly in the next year such an event could explain the otherwise anomalous earth based pre viking observations of a wet southern summer if southern ice deposits at lower latitudes are exposed the vapor can be transferred irreversibly through the strong hadley cell to the north polar cap we therefore speculate that the asymmetry of mars current orbit is responsible for the asymmetry of the present water distribution with extensive permanent water ice deposits located only in the colder aphelion summer northern hemisphere