on the wave number spectrum of oceanic mesoscale variability observed by the seasat altimeter variations of sea surface height measured by the seasat altimeter in nearly repeat orbits during the last 24 days of the mission are used to compute the wave number spectrum of mesoscale variability in various parts of the oceans the instrument noise level 150 cm2 cycles km has limited the resulting oceanic spectrum to wavelengths longer than 100 km we found that the characteristics of the oceanic spectrum are dependent on the energy level of the mesoscale variability in the high energy areas close to major current systems most of the energy is contained at wavelengths longer than 250 km at wavelengths shorter than 250 km the spectrum basically follows a k 5 k is wave number dependence in the low energy areas remote from major current systems the spectrum follows a k 1 dependence at wave lengths from 100 to 1000 km based on the assumption of horizontal isotropy of mesoscale variability scalar wave number spectra of sea surface height and geostrophic kinetic energy are also presented dynamical implications of these spectra are discussed the effects of residual geoid and atmospheric water vapor on the computed oceanic spectra have been rigorously examined it was found that the general characteristics of the oceanic spectra were not significantly affected by them

an evaluation of the barotropic and internal tides in a high resolution global ocean circulation model 1 global comparisons of barotropic and internal tides generated in an eddy resolving ocean circulation model are made with tidal estimates obtained from altimetric sea surface heights and an altimetry constrained tide model as far as we know our hybrid coordinate ocean model hycom simulations shown here and in an earlier paper are the only published high resolution global simulations to contain barotropic tides internal tides the general circulation and mesoscale eddies concurrently comparing the model barotropic tide with a global data assimilative shallow water tide model shows that the global tidal elevation differences are approximately evenly split between discrepancies in tidal amplitude and phase both the model and observations show strong generation of internal tides at a limited number of hot spot regions with propagation of beams of energy for thousands of kilometers away from the sources the model internal tidal amplitudes compare well with observations near these energetic tidal regions averaged over these regions the model and observation internal tide amplitude estimates agree to approximately 15 for the four largest semidiurnal constituents and 23 for the four largest diurnal constituents away from the hot spots the comparison between the model and altimetric amplitude is not as good due in part to two problems errors in the model barotropic tides and overestimation of the altimetric tides in regions of strong mesoscale eddy activity examining the general energy distribution of the simulated internal tide is an important first step in the evaluation of internal tides in hycom

global wavenumber spectrum with corrections for altimeter high frequency noise the altimetry wavenumber spectra of sea surface height ssh provide a unique dataset for testing of geostrophicturbulence whilesshspectralslopesofk 211 3 andk 25 areexpectedfromtheoriesandnumerical simulations the altimetry spectra from the original unfiltered and instrument noise corrected data often are too shallow falling between k 22 and k 23 in this study the possibility that the flattened spectral slopes are partly due to contamination by unresolved high frequency 10 days motions is tested a spatiotemporal filter based on empirical orthogonal function expansion eof is used to remove the temporally incoherent signals the resulting spectral slopes are much steeper than in the previous studies over 70 of the revised global spectral estimates excluding the tropics are above k 23 moreover in high energy regions like the gulf streamandkuroshio thespectralslopesare aboutk 25 whichis consistentwiththeclassicalquasigeostrophic qg turbulence the spectral slopes are validated with the eddy kinetic energy eke spectra from shipboard acoustic doppler current profiler adcp measurements in the high and low energy regions

the influence of coatings and fills on flow in fractured unsaturated tuff porous media systems a numerical study of a single fracture embedded in a porous matrix was performed to investigate the role of fracture coatings and fills on water movement in permeable fractured porous media the variables considered were conductivity and continuity of fracture coatings location length and conductivity of fracture fills combinations of fills and coatings initial matrix saturation and inflow boundary conditions results from the simulations indicate that in low saturation high capillarity tuff systems the conditions under which fractures act as rapid flow paths are limited these conditions include a continuous coating with conductivity several orders of magnitude lower than that of the neighboring matrix and large inflow rates however as initial matrix saturation increases the amount of fracture flow also increases discontinuities in coatings substantially reduce their effectiveness in preventing matrix imbibition the presence of any coating however does produce increased infiltration depths fills appear to be effective barriers to fracture flow

wavenumber spectrum in the gulf stream from shipboard adcp observations and comparison with altimetry measurements the wavenumber spectra for velocity and temperature in the gulf stream region are calculated from a decade 1994 2004 of shipboard acoustic doppler current profiler adcp measurements taken as part of the oleander project the velocity and temperature spectra have comparable magnitude in terms of the kinetic and potential energy and both indicate a k 23 slope in the mesoscales in contrast the corresponding velocity spectrum determined from satellite altimetry sea surface heights yields a significantly higher energy level and a k 22 slope the discrepancy between altimeter derived and directly measured velocity spectra suggests that altimetric velocity probably is contaminated by noise in sea surface height measurement also the k 23 slope which appears to be in agreement with two dimensional quasigeostrophic turbulence theory does not support the contemporary surface quasigeostrophic theory these results highlight large gaps in the current understanding of the nature of surface geostrophic turbulence

special speleothems in cement grouting tunnels and their implications of the atmospheric co2 sink based on the analyses and comparisons of water chemistry stable carbon isotopes and deposition rates of speleothems the authors found that there are two kinds of speleothems in the tunnels at the wujiangdu dam site guizhou china namely the co2 outgassing type and the co2 absorbing type the former is natural as observed in general karst caves and the product of karst processes under natural conditions the latter however is special resulting from the carbonation of a cement grouting curtain and concrete due to the quick absorption of co2 from the surrounding atmosphere evidenced by the low co2 content in the air and the high deposition rate of speleothems as high as 10 cm a in the tunnels the contribution of the carbonation process to the sink of co2 in the atmosphere is important in the order of magnitude of 108 tons c a and should be taken into consideration in the study of the global carbon cycle because of the use of cement on a worldwide scale

seepage into a mountain tunnel and rain infiltration abstract to clarify the processes governing recharge of rainwater into an unconfined aquifer in a mountain basin the seepage rate of water into a mountain tunnel was monitored continuously between may 1988 and december 1991 in yura wakayama western japan the electrical conductivity and ionic composition of the seepage water was also measured regularly from june 1989 the mountain is composed of fractured sedimentary rocks such as sandstones and cherts seepage appeared only at specific locations on the roof of the tunnel seepage was measured through overlying sandstones of 10 m depth and cherts of 5 m depth time variations in the discharge suggested that seepage is formed both by rapid flow and basic flow components which correspond to the so called fissure flow and matrix flow this was confirmed by analysis of time variations in the concentration of chemical species in the seepage water fissure flow contributes the initial increment of seepage discharge immediately after the occurrence of rainfall and its velocity for sandstone can be represented by a function only of water content n is constant and larger in winter than in summer but n remains constant at approximately two infiltration time in fissures through the base of the cherts is negligible compared with that through the overlying soil layer whereas matrix flow through sandstones persists through the year for cherts it disappears within a week after rainfall events and its decay is dependent on the seasonal magnitude of evapotranspiration the behavior of the matrix flow for sandstones can be analyzed through a kinematic wave model as can the fissure flow

space geodetic constraints on glacial isostatic adjustment in fennoscandia analysis of global positioning system gps data demonstrates that ongoing three dimensional crustal deformation in fennoscandia is dominated by glacial isostatic adjustment our comparison of these gps observations with numerical predictions yields an earth model that satis es independent geologic constraints and bounds both the average viscosity in the upper mantle 5 x 10 20 to 1 x 10 21 pascal seconds and the elastic thickness of the lithosphere 90 to 170 kilometers we combined gps derived radial motions with fennoscandian tide gauge records to estimate a regional sea surface rise of 2 1 0 3 mm year furthermore ongoing horizontal tectonic motions greater than 1 mm year are ruled out on the basis of the gps derived three dimensional crustal velocity field

atmospheric effects and spurious signals in gps analyses improvements in the analyses of global positioning system gps obser vations yield resolvable mm to sub mm di erences in coordinate estimates thus provid ing su cient resolution to distinguish subtle di erences in analysis methodologies here we investigate the e ects on site coordinates of using di erent approaches to modelling atmospheric loading deformation atml and handling of tropospheric delays the rig orous approach of using the time varying vmf1 mapping function yields solutions with lower noise at a range of frequencies compared with solutions generated using empiri cal mapping functions this is particularly evident when atml is accounted for some improvement also arises from using improved a priori zenith hydrostatic delays zhd with the combined e ect being site speci c importantly inadequacies in both mapping functions and a priori zhds not only introduce time correlated noise but signi cant pe riodic terms at solar annual and semi annual periods we nd no signi cant di erence between solutions where non tidal atml is applied at the observation level rather than as a daily averaged value but failing to model diurnal and semi diurnal tidal atml at the observation level can introduce anomalous propagated signals with periods that closely match the gps draconitic annual 351 4 d and semi annual period 175 7 d ex acerbated by not xing ambiguities these signals are evident in both stacked and sin gle site power spectra with each tide contributing roughly equally to the dominant semi annual peak the amplitude of the propagated signal reaches a maximum of 0 8 mm with a clear latitudinal dependence that is not correlated directly with locations of maximum tidal amplitude this is the first evidence of aliased signals being produced from tidal atml deformations

groundwater flow patterns in the vicinity of underground openings in unsaturated rock abstract a two dimensional modeling scheme is utilized herein to analyze the effects of mined out underground openings on groundwater flow patterns in unsaturated rocks a series of modeling results is presented using the finite element computer program unsat2 to simulate steady groundwater flow that initially is vertical and downward model output is analyzed for 1 variations in the direction of groundwater flow caused by the mined out openings 2 the distribution of pressure head as produced by the openings 3 variables that affect the rate of predicted groundwater inflow into the openings modeling results indicate that 1 mined out openings will alter the pattern of groundwater flow in the unsaturated zone 2 the hydraulic effects are dependent on the hydrogeology of the rocks and on the geometry of the mined out openings 3 inflow of groundwater into mined out openings is possible in the otherwise unsaturated zone including mines developed in homogeneous rocks 4 groundwater inflow into the mined out openings can occur at values of downward flux that are smaller in magnitude than the saturated hydraulic conductivity of the surrounding rock 5 the temporal and spatial distribution of flux through the topopah spring member of the paintbrush tuff is the most critical factor regarding the occurrence of mine water inflow in the otherwise unsaturated tuff at yucca mountain nd u s a

an active fracture model for unsaturated flow and transport in fractured rocks the unsaturated zone at yucca mountain a potential repository site of high level nuclear waste is a complex hydrologic system in which a variety of important flow and transport processes is involved to quantify these processes as accurately as possible is a theoretically challenging and practically important issue in this study we propose a new formulation for modeling flow and transport in unsaturated fractured rocks the formulation is mainly based on a hypothesis that only a portion of connected fractures are active in conducting water analysis of the relevant data with the new formulation suggests that about 18 27 of the connected fractures in the topopah spring welded tsw unit the potential repository unit of yucca mountain are active under ambient conditions the relatively high percentage of active fractures is consistent with field observations from a variety of sources sensitivity analyses are performed to investigate effects of the activity of connected fractures on flow and transport behavior in unsaturated rocks

a mechanistic model for water seepage through thick unsaturated zones in fractured rocks of low matrix permeability the theme developed in this paper is that water seepage in thick unsaturated zones in fractured rocks of low matrix permeability cannot be understood by considering spatial and temporal averages we suggest that most such seepage proceeds in an unsteady episodic manner in localized preferential pathways mechanisms are proposed and explored which permit water to flow relatively freely in networks of interconnected fractures in the presence of strong suction pressures from an unsaturated rock matrix imbibition into the rock matrix is reduced by limited wetted area the episodic nature of flow and possibly also by the presence of mineral coatings of low permeability on the fracture walls these effects and conditions combine to limit total imbibition rates to values less than saturated matrix hydraulic conductivity leaving the rock matrix in partially saturated conditions even as water is flowing freely in portions of the fracture network the proposed conceptual model is elaborated and substantiated with analytical estimates and numerical simulation studies mechanisms are demonstrated that can funnel distributed seepage into spatially localized preferential paths subsequent horizontal broadening from dispersive mechanisms is found to be a slow process for fractures of high intrinsic permeability the presence of an unsaturated rock matrix provides constraints on fracture matrix interface areas for imbibition and on the frequency of episodic deep seepage events further studies are needed to test the proposed model

using global positioning system derived crustal velocities to estimate rates of absolute sea level change from north american tide gauge records 1 we identified 37 tide gauges each located within 40 km of a geodetic station whose international terrestrial reference frame of 2000 itrf2000 crustal velocity had been rigorously derived from continuous global positioning system gps observations spanning from 3 to 11 years the tide gauges are located along the coasts of north america bermuda hawaii and kwajalein in the marshall islands we obtained the itrf2000 crustal velocities by averaging values from six solutions each produced by a team of investigators acting essentially independently of the other teams we then applied crustal velocities to convert rates of relative sea level change to rates of absolute sea level change in a sample containing 30 sites we found that the mean rate of absolute sea level change equals 1 80 0 18 mm yr in the 1900 1999 period the scatter about the mean for individual sites in this sample is characterized by a weighted rms value of 0 85 mm yr this scatter primarily reflects the uncertainty associated with derived crustal velocities the remaining seven sites i e five sites on the pacific coast of alaska one on dauphin island alabama and one on kwajalein an atoll in the pacific ocean experienced relatively low rates of absolute sea level change we hypothesize the low rates in alaska are caused by ongoing melting of mountain glaciers and ice masses near the stations while the low rates found for dauphin island and kwajalein remain unexplained

geochemical evidence of preferential flow of water through fractures in unsaturated tuff apache leap arizona abstract the occurrence and significance of aqueous flow through fractures in unsaturated tuff was investigated at the apache leap research site near superior arizona water samples for geochemical and isotopic analysis were collected from water seeping from fractures in a mine haulage tunnel from the saturated zone in a vertical borehole usw uzp 4 and from both the unsaturated and saturated zones in an angled borehole dsb the geochemistry and14c activity of water samples from the dsb suggest that most of the recharge to the saturated zone has occurred through fractures especially beneath the ephemeral streams evidence of substantial recent recharge through fractures was found in saturated zone samples from the mine haulage tunnel using 3h 34s and so42 cl analyses evidence of partial imbibition of fracture flow into the rock matrix was found at multiple depths throughout the 147 m unsaturated zone at the dsb using geophysical measurements from the borehole water content analyses from core samples and 14c and 3h analyses from pore water extracted from preserved core samples post bomb 14c activity was measured in pore water near fractures just above the saturated zone

impact of horizontal resolution 1 12 to 1 50 on gulf stream separation penetration and variability abstractthe impact of horizontal resolution 1 12 to 1 50 6 to 1 5 km at midlatitudes on gulf stream separation penetration and variability is quantified in a series of identical north atlantic experiments the questions the authors seek to address are twofold 1 is the realism of the modeled solution increased as resolution is increased 2 how robust is the modeled mesoscale and submesoscale eddy activity as a function of grid spacing and how representative is it of interior quasigeostrophic qg or surface quasigeostrophic sqg turbulence this study shows that i the representation of gulf stream penetration and associated recirculating gyres shifts from unrealistic to realistic when the resolution is increased to 1 50 and when the nonlinear effects of the submesoscale eddies intensifies the midlatitude jet and increases its penetration eastward ii the penetration into the deep ocean drastically increases with resolution and closely resembles the observations and iii surface power spec

interpreting energy and tracer spectra of upper ocean turbulence in the submesoscale range 1 200 km submesoscale 1 200km wavenumber spectra of kinetic and potential energy and tracer variance are obtained from in situ observations in the gulf stream region and in the eastern subtropical north pacific in the gulf stream region steep kinetic energy spectra at scales between 200 and 20km are consistent with predictions of interior quasigeostrophic turbulence theory both in the mixed layer and in the thermocline at scales below 20km the spectra flatten out consistent with a growing contribution of internal wave energy at small scales in the subtropical north pacific theenergyspectraareflatterand inconsistentwith predictionsofinteriorquasigeostrophic turbulence theory the observed spectra and their dependence on depth are also inconsistent with predictions of surface quasigeostrophic turbulencetheoryfortheobservedoceanstratification itappearsthatunbalancedmotions most likely internal tides at large scales and the internal wave continuum at small scales dominate the energy spectrum throughout the submesoscale range spectra of temperature variance along density surfaces which are not affected by internal tides are also inconsistent with predictions of geostrophic turbulence theories reasons for this inconsistency could be the injection of energy in the submesoscale range by small scale baroclinic instabilities or modifications of the spectra by coupling between surface and interior dynamics or by ageostrophic frontal effects

flow toward storage tunnels beneath a water table 1 two dimensional flow a system of parallel tunnels is excavated in saturated rock of low permeability for storing oil or lpg in order to contain the product permanent water inflow has to be maintained in absence of recharge this flow causes a continuous drop of the water table a numerical scheme based on the boundary integral elements method is used in order to determine the water table motion the inflow to galleries and the velocity on the perimeter both oil filled and empty galleries are considered the shape of the galleries is maintained fixed while the spacing and the distance to an impervious bottom is varied an analytical approximate solution valid for sufficiently high water table above the galleries top is also derived this solution is extended to the cases of vertical recharge above the free surface and lpg filled galleries the solution of the two dimensional flow problem can be used in order to determine 1 the time required for the water table to drop from its initial position to the gallery top or to the product level in absence of recharge 2 the water velocity on the gallery perimenter and 3 the total inflow to the gallery

approximate boundaries between different flow regimes in fractured rocks recent studies have shown how water films at near zero matric potentials on fracture surfaces could permit fast flow in unsaturated fractures the present work is aimed at delineating the ranges of conditions necessary to permit film flow the approximate matric potential needed to permit thickening of water films on fracture surfaces was estimated through correlating air entry matric potentials and permeabilities for a wide range of porous media an upper matric potential limit associated with saturating the fracture was related to the fracture aperture these two limits one dependent on matrix permeability and the other on fracture aperture delineate the matric potential range within which thick water films develop on fracture surfaces rocks with matrix permeabilities less than 10 14 m2 and fractures with apertures greater than 30 m permit some matric potential range over which thick water films can form highly transmissive films can develop on fracture surfaces only under near zero matric and pressure potentials

thermohaline variability in the upper ocean the main goal of this exploratory study is to determine how the temperature salinity relationship changes with horizontal length scale and depth in the ocean temperature and salinity were measured on a range of scales from 4 m to 1000 km towing a seasoar along isobars and isopycnals in the subtropical gyre of the north pacific during the winter of 1997 the wavelet transform technique is used to compute the horizontal density ratio and thermohaline variability as a function of scale and location measurements along an isobar in the mixed layer show that the horizontal density ratio is 1 at all scales observed that is horizontal temperature and salinity gradients tend to cancel each other in their effect on density thermohaline variability at small scales is intermittent and clusters around large scale thermohaline anomalies below the base of the mixed layer horizontal gradients of temperature are only partially opposed by salinity and the density ratio is close to 2 in the thermocline the distribution of thermohaline variability is uniform along isobars but intermittent and colocated at different scales along isopycnals density compensated variability ubiquitous in the mixed layer is reduced along deeper isopycnals compensation of horizontal temperature and salinity gradients supports recent theoretical ideas that mixing in the winter mixed layer depends on horizontal density gradients

surface manifestation of internal tides generated near hawaii analysis of topex poseidon satellite altimetry reveals short wavelength fluctuations in the ocean surface tide that are attributable to internal tides a significant fraction of the semidiurnal internal tide generated at the hawaiian ridge is evidently phase locked to the astronomical potential and can modulate the amplitude of the surface tide by 5 cm the internal tide is thus easily mapped along satellite groundtracks and it is found to be spatially coherent over great distances with waves propagating well over 1000 km from the hawaiian ridge before decaying below noise level both first and second baroclinic modes are observed in both the m 2 lunar and s 2 solar tides the high space time coherence is in sharp contrast to what is often inferred from current meter observations but it confirms recent speculations from an acoustic experiment north of hawaii

spatial scales of mesoscale variability in the north atlantic as deduced from geosat data two years of geosat data were used to systematically investigate the mesoscale variability and spatial scales of the north atlantic we first calculated sea surface height variability and eddy kinetic energy these compare well with the eddy kinetic energy obtained with surface drifters then the spatial scales of mesoscale variability were characterized in 10 latitude 10 longitude areas by their wave number spectra and autocorrelation functions comparison with existing in situ data shows good agreement and it is believed that the total error budget is globally below that of the oceanic signal the wave number spectra show significant differences as a function of latitude and longitude and these can be related to different types of forcing instability of a mean current or fluctuating wind scales typically decrease from west to east and south to north simple proportionality with respect to the first internal rossby radii does not apply everywhere

water recharge and solute transport through the vadose zone of fractured chalk under desert conditions this study focuses on water flow and solute migration through unsaturated fractured chalk in an arid area the chalk underlies a major industrial complex in the northern negev desert where groundwater contamination has been observed four dry drilling holes were bored through the vadose zone core and auger samples collected at 30 to 50 cm intervals were used for chemical and isotopic analyses enabling the construction of the following profiles 1 a tritium profile to estimate the rate of water flow through the unsaturated zone 2 oxygen 18 and deuterium profiles to assess the evaporation of water at land surface before percolation and in the upper part of the vadose zone after infiltration and 3 chloride and bromide profiles as tracers for inert solutes and pollutants the tritium and bromide profiles showed the rate of infiltration through the unsaturated matrix to be very slow 1 6 11 cm yr the chemical and isotopic data from the core holes suggested that the pore water changes characteristics with depth close to land surface the pore water is strongly evaporated 18o 5 94 and highly concentrated 29 meq cl 100 g rock but changes gradually with depth to amore dilute concentration 4 meq cl 100 g rock and isotopically depleted composition 18o 4 4 closer to the isotopic composition of precipitation and groundwater nearby monitoring wells have shown anthropogenic contribution of heavy metals organic compounds and tritium nativ and nissim 1992 a conceptual model is proposed in which a small portion of the rainwater percolates downward through the matrix while a larger percentage of the percolating water moves through preferential pathways in fractures the water flowing through the fractures penetrates the matrix across the fracture walls where it increases the tritium concentrations depletes the stable isotopic composition and dilutes the salt concentrations the observed rapid downward migration of tritium and heavy metals through the profuse fractures makes the chalk inefficient as a hydrologic barrier

study of the atmospheric pressure loading signal in very long baseline interferometry observations 1 redistribution of air masses due to atmospheric circulation causes loading deformation of the earth s crust which can be as large as 20 mm for the vertical component and 3 mm for horizontal components rigorous computation of site displacements caused by pressure loading requires knowledge of the surface pressure field over the entire earth surface a procedure for computing three dimensional displacements of geodetic sites of interest using a 6 hourly pressure field from the national centers for environmental prediction numerical weather models and the ponte and ray 2002 model of atmospheric tides is presented we investigated possible error sources and found that the errors of our pressure loading time series are below the 15 level we validated our model by estimating the admittance factors of the pressure loading time series using a data set of 3 5 million very long baseline interferometry observations from 1980 to 2002 the admittance factors averaged over all sites are 0 95 0 02 for the vertical displacement and 1 00 0 07 for the horizontal displacements for the first time horizontal displacements caused by atmospheric pressure loading have been detected the closeness of these admittance factors to unity allows us to conclude that on average our model quantitatively agrees with the observations within the error budget of the model at the same time we found that the model is not accurate for several stations that are near a coast or in mountain regions we conclude that our model is suitable for routine data reduction of space geodesy observations

space geodetic measurement of crustal deformation in central and southern california 1984 1992 we estimate the velocity field in central and southern california using global positioning system gps observations from 1986 to 1992 and very long baseline interferometry vlbi observations from 1984 to 1991 our core network includes 12 gps sites spaced approximately 50 km apart mostly in the western transverse ranges and the coastal borderlands the precision and accuracy of the relative horizontal velocities estimated for these core stations are adequately described by a 95 confidence ellipse with a semiminor axis of approximately 2 mm yr oriented roughly north south and a semimajor axis of approximately 3 mm yr oriented east west

troposphere mapping functions for gps and very long baseline interferometry from european centre for medium range weather forecasts operational analysis data 1 in the analyses of geodetic very long baseline interferometry vlbi and gps data the analytic form used for mapping of the atmosphere delay from zenith to the line of site is most often a three parameter continued fraction in 1 sin elevation using the 40 years reanalysis era 40 data of the european centre for medium range weather forecasts for the year 2001 the b and c coefficients of the continued fraction form for the hydrostatic mapping functions have been redetermined unlike previous mapping functions based on data from numerical weather models isobaric mapping functions niell 2000 and vienna mapping functions vmf boehm and schuh 2004 the new c coefficients are dependent on the day of the year and unlike the niell mapping functions niell 1996 they are no longer symmetric with respect to the equator apart from the opposite phase for the two hemispheres compared to vmf this causes an effect on the vlbi or gps station heights that is constant and as large as 2 mm at the equator and that varies seasonally between 4 mm and 0 mm at the poles the updated vmf based on these new coefficients and called vmf1 hereinafter yields slightly better baseline length repeatabilities for vlbi data the hydrostatic and wet mapping functions are applied in various combinations with different kinds of a priori zenith delays in the analyses of all vlbi international vlbi service for geodesy and astrometry ivs r1 and ivs r4 24 hour sessions of 2002 and 2003 the investigations concentrate on baseline length repeatabilities as well as on absolute changes of station heights

global mapping functions for the atmosphere delay at radio wavelengths i have developed expressions for calculating the ratios mapping functions of the line of sight hydrostatic and wet atmospheric path delays to their corresponding zenith delays at radio wavelengths for elevation angles down to 3 the coefficients of the continued fraction representation of the hydrostatic mapping function depend on the latitude and height above sea level of the observing site and on the day of the year the dependence of the wet mapping function is only on the site latitude by comparing with mapping functions calculated from radiosonde profiles for sites at latitudes between 43 s and 75 n the hydrostatic mapping function is seen to be more accurate than and of comparable precision to mapping functions currently in use which are parameterized in terms of local surface meteorology when the new mapping functions are used in the analysis of geodetic very long baseline interferometry vlbi data the estimated lengths of baselines up to 10 400 km long change by less than 5 mm as the minimum elevation of included data is reduced from 12 to 3 the independence of the new mapping functions from surface meteorology while having comparable accuracy and precision to those that require such input makes them particularly valuable for those situations where surface meteorology data are not available

non stationary internal tides observed with satellite altimetry 1 temporal variability of the internal tide is inferred from a 17 year combined record of topex poseidon and jason satellite altimeters a global sampling of along track sea surface height wavenumber spectra finds that non stationary variance is generally 25 or less of the average variance at wavenumbers characteristic of mode 1 tidal internal waves with some exceptions the non stationary variance does not exceed 0 25 cm2 the mode 2 signal where detectable contains a larger fraction of non stationary variance typically 50 or more temporal subsetting of the data reveals interannual variability barely significant compared with tidal estimation error from 3 year records comparison of summer vs winter conditions shows only one region of noteworthy seasonal changes the northern south china sea implications for the anticipated swot altimeter mission are briefly discussed

aliased tidal signatures in continuous gps height time series 1 coordinate time series are often derived from continuous gps data processed as discrete 24 hour solutions under this regimen residual semi diurnal and diurnal crustal tide signatures are under sampled resulting in aliased periodic signals in the coordinate time series a secondary aliasing effect well known from satellite altimetry studies but generally ignored in gps analysis arises from the repeat period of the satellite orbits being longer than the nyquist period of the semi diurnal and diurnal tidal signatures this paper derives the theoretical periods for these two aliasing effects for the principal semi diurnal and diurnal tidal constituents the presence of both types of aliased signals in gps time series is then demonstrated using simulated gps data and also considered for time series derived from real gps data it is shown that the beating of the two aliased signals invariably results in spurious signatures in the time series with semi annual and annual periods

mesoscale to submesoscale transition in the california current system part i flow structure eddy flux and observational tests in computational simulations of an idealized subtropical eastern boundary upwelling current system similar to the california current a submesoscale transition occurs in the eddy variability as the horizontal grid scale is reduced to o 1 km this first paper in a series of three describes the transition in terms of the emergent flow structure and the associated time averaged eddy fluxes in addition to the mesoscale eddies that arise from a primary instability of the alongshore wind driven currents significant energy is transferred into submesoscale fronts and vortices in the upper ocean the submesoscale arises through surface frontogenesis growing off upwelled cold filaments that are pulled offshore and strained in between the mesoscale eddy centers in turn some submesoscale fronts become unstable and develop submesoscale meanders and fragment into roll up vortices associated with this phenomenon are a large vertical vorticity and rossby number a large vertical velocity relatively flat horizontal spectra contrary to the prevailing view of mesoscale dynamics a large vertical buoyancy flux acting to restratify the upper ocean a submesoscale energy conversion from potential to kinetic a significant spatial and temporal intermittency in the upper ocean and material exchanges between the surface boundary layer and pycnocline comparison with available observations indicates that submesoscale fronts and instabilities occur widely in the upper ocean with characteristics similar to the simulations

ssh wavenumber spectra in the north pacific from a high resolution realistic simulation abstractfollowing recent studies based on altimetric data this paper analyses the spectral characteristics of the sea surface height ssh using a new realistic simulation of the north pacific ocean with high resolution in the horizontal and 100 vertical levels this simulation resolves smaller scales down to 10 km than altimetric data limited to 70 km because of the noise level in high eddy kinetic energy eke regions as in the western part ssh spectral slope almost follows a k 4 with k the wavenumber or slightly steeper law in agreement with altimeter studies the new result is that unlike altimeter studies such a k 4 slope is also observed in low eke regions as in the eastern part in these regions this slope mostly concerns scales not well resolved by altimetric data such k 4 ssh spectral slopes are weaker from what is expected from quasigeostrophic turbulence theory but closer to surface quasigeostrophic sqg turbulence theory the consequence is that the small scales concerned

dripping into unsaturated rock underground excavations literature review and geologic and hydrogeologic setting description a literature review of dripping in underground constructions in deep unsaturated geologic media was performed as part of a phased study the objective is to develop and test a formulation that can be used for studying unsaturated flow through rough multi segmented fractures with emphasis on predicting dripping initiation time geologic and hydrogeologic setting for the yucca mountain ym and its exploratory studies facility which is the site where the model will be tested are described

do altimeter wavenumber spectra agree with the interior or surface quasigeostrophic theory in high eddy energy regions it is generally assumed that sea level wavenumber spectra compare well with quasigeostrophic qg turbulence models and that spectral slopes are close to the expected k 5 law this issue is revisited here sea level wavenumber spectra in the gulf stream kuroshio and agulhas regions are estimated using the most recent altimeter datasets the ocean topography experiment topex poseidon jason 1 the environmental satellite envisat and the geosat follow on the authors show that spectral slopes in the mesoscale band are significantly different from a k 5 law in disagreement with the qg turbulence theory however they very closely follow a k 11 3 slope which indicates that the surface quasigeostrophic theory sqg is a much better dynamical framework than the qg turbulence theory to describe the ocean surface dynamics because of the specific properties of the sqg theory these results offer new perspectives for the analysis and interpretation of satellite data

gps height time series short period origins of spurious long period signals gps height time series used in geophysical studies are often formed from discrete continuous nonoverlapping 24 hour processing sessions with such a strategy unmodeled periodic ground displacements with approximately semidiurnal and diurnal periods have often been assumed to average close to zero by analyzing several years of continuous gps data from globally distributed sites at which controlled errors were not modeled this paper shows such an assumption to be erroneous it is shown that each unmodeled sub daily periodic displacement can propagate to several spurious long wavelength features in a gps height time series ranging in period from about 2 weeks to 1 year admittances ratio of amplitude of spurious long wavelength output signal in the gps height time series to amplitude of unmodeled periodic ground displacement depend on the coordinate component and the tidal constituent considered for example it is shown that an unmodeled s2 north component periodic ground displacement can propagate to a semiannual height signal with admittance of greater than 100 whereas the height admittance is around 5 10 since model errors in ocean tide loading atmospheric pressure loading and solid earth tide displacement amplitudes can be several millimeters long wavelength spurious signals of up to these amplitudes may be expected to appear in gps height time series this paper provides an indication of how such errors will propagate where such errors are greatest and hence how spurious fortnightly semiannual and in some cases annual effects may be present at some sites copyright 2007 by the american geophysical union

infiltration of a liquid front in an unsaturated fractured porous medium we consider liquid infiltrating by gravity flow into a system of parallel regularly spaced fractures in an unsaturated porous medium the position of the fracture liquid front as a function of time under some simplifying assumptions is shown to obey a nonlinear integrodifferential equation approximate analytic solutions are developed showing that the movement of the liquid front exhibits three major flow periods 1 at early time the frontal position is determined by the fracture inlet boundary condition and the gravity driven flow behavior of the fracture with negligible influence by the matrix 2 at intermediate time matrix imbibition retards the frontal advance against the pull of gravity 3 at late time the matrix approaches saturation and the frontal velocity approaches a limiting value a two dimensional numerical model is used to confirm the approximate solutions implications of the model for nuclear waste storage are discussed the analysis is applicable not only to fractured rock but also to lateral infiltration into coarse grained sediments lying between layers of fine grained soil

inferring dynamics from the wavenumber spectra of an eddying global ocean model with embedded tides 1 the slopes of the wavenumber spectra of sea surface height ssh and kinetic energy ke have been used to infer interior or surface quasi geostrophic qg or sqg dynamics of the ocean however inspection of spectral slopes for altimeter ssh in the mesoscale band of 70 to 250 km shows much flatter slopes than the qg or sqg predictions over most of the ocean comparison of altimeter wavenumber spectra with spectra from an eddy resolving global ocean circulation model the hybrid coordinate ocean model hycom at 1 12 5 equatorial resolution which has embedded tides suggests that the flatter slopes of the altimeter ssh may arise from three possible sources 1 presence of strong internal tides 2 shift of the inertial sub range to smaller scales and 3 altimeter noise artificially adding noise to the model tends to flatten the spectra for low ke regions near internal tide generating regions spectral slopes in the presence of internal waves are much flatter than qg or sqg predictions separating the variability into high and low frequency around periods of 2 days then a different pattern emerges with a flat high frequency wavenumber spectrum and a steeper low frequency wavenumber spectrum for low mesoscale ke the inertial sub range defined by the nearly flat enstrophy band moves to smaller scales and the mesoscale band of 70 to 250 km no longer represents the inertial sub range the model wavenumber spectra are consistent with qg and sqg theory when internal waves and inertial sub range shifts are taken into consideration

fracture matrix interaction in a fracture of finite extent 1 the behavior of a wetting front invading a fracture in an unsaturated porous matrix is of some importance for understanding infiltration and recharge processes contaminant transport and similar topics previous investigators have examined this problem and a number of models have been published in the literature it is however difficult to observe processes inside a fracture particularly in a field setting many models of fracture flow and fracture matrix interaction therefore lack an observable quantity and instead rely on comparisons with numerical simulations to test the validity of the theoretical constructs here a method is proposed that avoids this difficulty by analyzing flow in a finite fracture or fracture network the fracture is considered finite because after some interval of injecting water to the fracture at a constant rate the wetting front reaches the far end of the fracture and exits at a point where it can be monitored the discharge from the fracture constitutes an observable quantity and allows comparison with field or laboratory data a curve matching procedure is described by which parameters characterizing the fracture matrix system may be estimated and the method is demonstrated using output from a numerical simulation data from a laboratory experiment and data from two field tests

the effects of altimeter instrument noise on the estimation of the wavenumber spectrum of sea surface height the wavenumber spectrum of sea surface height ssh observed by satellite altimetry was analyzed by xu and fu the spectral shape in the wavelength range of 70 250 km was approximated by a power law representing a regime governed by geostrophic turbulence theories the effects of altimeter instrument noise were assumed insignificant at wavelengths longer than 70 km the authors reexamined the assumption in the study using nearly simultaneous observations made by jason 1 and jason 2 during their cross calibration phase this study found that the white noise level of altimetry measurement was best estimated from the spectral values at wavelengths from 25 to 35 km after removing a white noise level based on such estimate from the ssh spectrum the spectral slope values changed significantly over most of the oceans a keyfinding is that the spectral slopes are generally steeper than k 22 k is wavenumber poleward of the 208 latitudes where flatter spectral slopes in some regions have previously caused problems for dynamic interpretations the new results indicate that the spectral slopes in the core regions of the major ocean current systems have values between the original geostrophic turbulence theory and the surface quasigeostrophic theory the near k 24 spectrum suggests that the sea surface height variability at these wavelengths in the high eddy energy regions might be governed by frontogenesis

detection of crustal deformation from the landers earthquake sequence using continuous geodetic measurements the measurement of crustal motions in technically active regions is being performed increasingly by the satellite based global positioning system gps 1 2 which offers considerable advantages over conventional geodetic techniques3 4 continuously operating gps arrays with ground based receivers spaced tens of kilometres apart have been established in central japan5 6 and southern california to monitor the spatial and temporal details of crustal deformation here we report the first measurements for a major earthquake by a continuously operating gps network the permanent gps geodetic array pgga 7 9 in southern california the landers magnitude afw of 7 3 and big bear mw 6 2 earthquakes of 28 june 1992 were monitored by daily observations ten weeks of measurements centred on the earthquake events indicate significant coseismic motion at all pgga sites significant post seismic motion at one site for two weeks after the earthquakes and no significant preseismic motion these measurements demonstrate the potential of gps monitoring for precise detection of precursory and aftershock seismic deformation in the near and far field

global variability of the wavenumber spectrum of oceanic mesoscale turbulence abstractthe wavenumber spectra of sea surface height from satellite altimeter observations have revealed complex spatial variability that cannot be explained by a universal theory of mesoscale turbulence near the edge of the core regions of high eddy energy agreement is observed with the prediction of the surface quasigeostrophic sqg turbulence theory which has fundamental differences from that of the traditional quasigeostrophic qg turbulence theory in the core regions of high eddy energy the spectra are consistent with frontogenesis that is not fully accounted for by the sqg theory however the observations in the vast ocean interior of low eddy energy exhibit substantial differences from the predictions of existing theories of oceanic mesoscale turbulence the spectra in these regions may reflect the ocean s response to short scale atmospheric forcing and air sea interaction the observations presented in this paper serve as a test bed for new theories and ocean general circulation models

southern california permanent gps geodetic array error analysis of daily position estimates and site velocities we analyze time series of daily positions estimated from data collected by 10 continuously monitoring global positioning system gps sites in southern california during the 19 month period between the june 28 1992 mw 7 3 landers and january 17 1994 mw 6 7 northridge earthquakes each time series exhibits a linear tectonic signal and significant colored noise spectral power at frequencies in the range 5 yr 1 to 0 5 d 1 is dominated by white noise or possibly fractal white noise and is several orders of magnitude higher than what would be expected from random walk noise in this short period range attributed by others to geodetic monument motions estimating a single slope for the time series power spectra suggests fractal white noise processes with spectral indices of about 0 4 site velocity uncertainties assuming this fractal white noise model are 2 4 times larger than uncertainties obtained assuming a purely white noise model a combination white noise plus flicker noise spectral index of 1 model also fits the data and suggests that the velocity uncertainties should be 3 6 times larger than for the white noise model we cannot adequately distinguish between these two noise models nor can we rule out the possibility of a random walk signal at the lowest frequencies these questions await the analysis of longer time series in any case reducing the magnitude of low frequency colored noise is critical and appears to be best accomplished by building sites with deeply anchored and braced monuments otherwise rate uncertainties estimated from continuous gps measurements may not be improved significantly compared to those estimated from infrequent campaign mode measurements

validating satellite altimeter measurements of internal tides with long term tao triton buoy observations at 2 s 156 e satellite altimetry is regularly used to map the global distribution of mode 1 internal tides validating altimeter measurements of internal tides with in situ data is difficult as the mooring observations typically are too short compared with the altimetry here taking advantage of the long term since 1999 tropical atmosphere ocean triangle trans ocean buoy network tao triton buoy observations at 2 s 156 e located at a topex poseidon crossover in a region of strong internal tides direct comparisons are made between altimeter and in situ measurements over a common 15 year period the hourly buoy data are decimated every 9 9 day to emulate altimeter measurements the altimeter and decimated buoy data are highly coherent at the aliased semidiurnal period 60 day and they agree well for the stationary semidiurnal internal tide for the nonstationary internal tide which consists of a significant annual cycle the demodulated amplitude from the altimeter appears to be contaminated by nontidal signals the demodulated amplitude from the decimated buoy data on the other hand is capable of resolving the temporal variability this suggests the potential of mapping nonstationary internal tides from satellites