some observations on suspended sediment dynamics in storbregrova jotunheimen observations are reported of the dynamics of suspended sediment transport in the meltstream of storbreen in the jotunheimen fine sediment is transferred from the subglacial to the proglacial environment during low flow meltdominated periods and then removed from the catchment during high flow rainfall controlled events both diurnal and storm period sediment load discharge relationships involve clockwise hysteresis but separate multivariate rating curves define variations of load with streamflow according to 1 the relative importance of meltwater and rainfall runoff and 2 changes in the sediment source areas contributing to the stream at different times particle size variations in the suspended sediment also reflect varying source area influences

contemporary rates of chemical denudation and atmospheric co2 sequestration in glacier basins an arctic perspective this paper presents new estimates of solute fluxes from five high arctic glacier basins in svalbard these estimates are combined with data from two other glacier basins to assess the effectiveness of chemical denudation on svalbard and to estimate rates of temporary or transient co2 drawdown we use a solute provenance model to partition solutes into marine aerosol atmospheric and crustal components and to estimate their annual fluxes crustally derived solute fluxes are equivalent to a mean chemical denudation rate of 350 meq m 2 a 1 for svalbard range 160 560 meq m 2 a 1 which lies within the global range of 94 4200 meq m 2 a 1 for 21 glacier basins in the northern hemisphere and is close to the continental average of 390 meq m 2 a 1 specific annual discharge is the most significant control upon chemical denudation in the glacierized basins and basin lithology is an important secondary control with carbonate rich and basaltic lithologies currently showing the greatest chemical denudation rates estimates of transient co2 drawdown are also directly associated with specific annual discharge and rock type on svalbard transient co2 drawdown lies in the range 110 3000 kg c km 2 a 1 whilst the range is 110 13000 kg c km 2 a 1 for the northern hemisphere glacial data set transient co2 drawdown is therefore usually low in the svalbard basins unless carbonate or basalt rocks are abundant the analysis shows that a large area of uncertainty in the transient co2 drawdown estimates exists due to the non stoichiometric release of solute during silicate hydrolysis silicate hydrolysis is particularly non stoichiometric in basins where the extent of glacierization is high which is most probably an artefact of high flushing rates through ice marginal and subglacial environments where k feldspars are undergoing mechanical comminution copyright 2000 john wiley sons ltd

solute provenance transport and denudation in a high arctic glacierized catchment recent understanding of chemical weathering in glacierized catchments has been focused on mid latitude alpine catchments comparable studies from the high latitudes are currently lacking this paper attempts to address this deficiency by examining solute provenance transport and denudation in a glacierized catchment at 78 n in the svalbard high arctic archipelago representative samples of snow glacier ice winter proglacial icing and glacier meltwater were obtained from the catchment during spring and summer 1993 and analysed for major ion chemistry seasonal variations in the composition of glacier meltwater occur and are influenced by proglacial solute acquisition from the icing at the very start of the melt season and subsequently by a period of discharge of concentrated snowmelt caused by snowpack elution weathering within the ice marginal channels that drain the glacier particularly carbonation reactions continues to furnish solute to meltwater when suspended sediment concentrations increase later in the melt season partitioning the solute flux into its various components sea salt crustal aerosol and atmospheric sources shows that c 25 of the total flux is sea salt derived consistent with the maritime location of the glacier and c 71 is crustally derived estimated chemical denudation 160 meq m 2 a 1 sea salt corrected cation equivalent weathering rate is somewhat low compared with other studied glacierized catchments estimates in the range 450 1000 meq m 2 a 1 which is probably attributable to the relatively short melt season and low specific runoff in the high arctic a positive relationship was identified between discharge and co 2 drawdown owing to carbonation reactions in turbid meltwater

persistent upwelling and front over the sulu ridge and their variations the persistent upwelling and front isolated over the sulu ridge are newly detected by a suite of satellite measurements and confirmed by historical cruise observations a three dimensional tide circulation coupled model is employed to investigate the dynamic mechanisms the intense vertical velocity shear induced by the vigorous internal tidal mixing is identified as the vital dynamic factor to trigger the upwelling and nutrient pumping through the strong tide topography interactions satellite observations indicate that the pronounced surface cooling and phytoplankton bloom are isolated over the sulu ridge throughout the year the steady front characterizes 10 20 km width and strength over 0 3 degrees c km near the southern edge the feature is further confirmed by the numerical simulation and in situ hydrological observation modeling experiment suggests that a quasi symmetrical vertical circulation bifurcation across the sulu ridge due to the asymmetry of tidal currents is the main mechanism to maintain the persistent upwelling and front moreover the local wind forcing plays an important regulating role in the seasonal and interannual variations the surface cooling and thermal front intensity reach the maximum in winter under the forcing of strong northeasterly monsoons due to prolonged el nino southern oscillation enso effects the surface cooling was significantly weakened during 1998 and 2010 summer further analysis indicates the fact that the southwesterly monsoon is weakened dramatically as part of the anticyclonic atmospheric circulation anomalies over the northwest pacific the latter results from the significant influence of tropical indian ocean capacitor effect associated with el nino southern oscillation

the impact of observed variations in the shear to strain ratio of internal waves on inferred turbulent diffusivities abstractthe most comprehensive studies of the spatial and temporal scales of diffusivity rely on internal wave parameterizations that require knowledge of finescale shear and strain studies lacking either shear or strain measurements have to assume a constant ratio between shear and strain r data from 14 moorings collected during five field programs are examined to determine the spatial and temporal patterns in r and the influence of these patterns on parameterized diffusivity time mean r ranges from 1 to 10 with changes of order 10 observed over a broad range of scales temporal variability in r is observed at daily weekly and monthly scales observed changes in r could produce a 2 3 times change in parameterized diffusivity vertical profiles of r eshear and estrain shear or strain variance relative to garret munk reveal that both local topographic properties and wind variability impact the internal wave field time series of r from each mooring have strong correlations to either shea

persistent near diurnal internal waves observed above a site of m2 barotropic to baroclinic conversion abstract near diurnal internal waves were observed in velocity and shear measurements from a shipboard survey along a 35 km section of the kaena ridge northwest of oahu individual waves with upward phase propagation could be traced for almost 4 days even though the ship transited approximately 20 km depth time maps of shear were dominated by near diurnal waves despite the fact that kaena ridge is a site of considerable m2 barotropic to baroclinic conversion guided by recent numerical and observational studies it was found that a frequency of m2 i e 24 84 h period was consistent with these waves nonlinear processes are able to transfer energy within the internal wave spectrum bicoherence analysis which can distinguish between nonlinearly coupled waves and waves that have been independently excited suggested that the m2 waves were nonlinearly coupled with the dominant m2 internal tide only between 525 and 595 m depth this narrow depth range corresponded to an observed m2 characteristic ema

monsoon surges trigger oceanic eddy formation and propagation in the lee of the philippine islands 1 two winter monsoon surge events northerly and easterly of january 2005 are captured in a one way coupled atmosphere 8 km resolution and ocean 3 km resolution simulation of the philippines region intensified wind jets and wakes in the lee of mindoro and luzon islands induce the generation and migration of a pair of counter rotating oceanic eddies in the model with propagation direction related to the orientation of the winds during each of the surges features shared by the eddies include size 100 200 km depth 300 m and propagation speed 0 1 0 15 m s 1 for cyclones mean wintertime model wind stress positive negative curl coincides with the climatological cyclone anticyclone distribution from a prior 8 year altimetry based census of eddies in the southeast quadrant of the south china sea during the winter monsoon moreover the simulation results agree with contemporaneous satellite and historical in situ data characterizing regional oceanic eddy and atmospheric surface jet properties

internal swell generation the spatial distribution of energy flux from the wind to mixed layer near inertial motions the energy flux from the wind to inertial mixed layer motions is computed for all oceans from 50 8 st o 508n for the years 1996 99 the wind stress t is computed from 6 h 2 58 resolution ncep ncar global reanalysis surface winds the inertial mixed layer response ui and the energy flux p5 t ui are computed using a slab model the validity of the reanalysis winds and the slab model is demonstrated by direct comparison with wind and adcp velocity records from ndbc buoys at latitudes 508 the inertial response is too fast to be resolved by the reanalysis wind 6 h output interval midlatitude storms produce the greatest fluxes resulting in broad maxima near 40 8 latitude during each hemisphere s winter concentrated in the western portion of each basin northern hemisphere fluxes exceed those in the southern hemisphere by about 50 the global mean energy flux from 1996 to 1999 and 508 st o 508n is 0 98 6 0 08 3 1023 wm 22 for a total power of 0 29 tw 1 tw 5 1012 w this total is the same order of magnitude as recent estimates of the global power input to baroclinic m2 tidal motions suggesting that windgenerated near inertial waves may play an important role in the global energy balance

an integrated approach to modelling hydrology and water quality in glacierized catchments the results are summarized of an integrated investigation of glacier geometry ablation patterns water balance meltwater routing hydrochemistry and suspended sediment yield the ultimate objective is to evaluate the assumptions of lumped two component mixing models as descriptors of glacier hydrology and to develop a semi distributed physically based model as an alternative the results of the study demonstrate that a reconstruction of probable subglacial drainage alignments can be achieved through a combination of terrain modelling based on estimated potential surface and dye tracing experiments recession curve analysis evidence of the seasonal instability of the englacial and subglacial electrical conductivities assumed in a mixing model evidence of the non conservative behaviour of water chemistry in the presence of suspended sediment and evidence of the seasonal evolution of the subglacial drainage system based on dye tracing all indicate that an alternative to a lumped static model of the hydrology is necessary the alternative presented in this paper is based on the combination of an energy balance model for surface melt which operates on an hourly time step and accounts for the changing spatial distribution of melt through the day as shading patterns change and routing procedures that transfer surface melt to moulins on the basis of glacier surface gradients then route water through reconstructed conduit systems using a hydraulic sewer flow routing procedure

observations of overturning in the thermocline the context of ocean mixing abstract the time sequence of events that lead to internal wave breaking and ocean turbulence is investigated data are obtained from depths 100 400 m with a repeat profiling ctd and a coded pulse doppler sonar the instruments were deployed from r p flip during february march 1995 while stationed 30 km west of point arguello california as an aspect of the marine boundary layer experiment although the water depth at the site is 1500 m both rms shear and diapycnal diffusivity as inferred from the average rate and size of overturning events increase with depth below 250 m a deep source of wave energy is implied depth time series of 6 4 m shear s 2 m strain n2 n2 where n is the buoyancy frequency 6 4 m gradient richardson number ri n2 s2 and 2 m effective strain rate the depth derivative of ctd inferred vertical velocity are obtained at 4 minute intervals over a 9 day 100 400 m domain the occurrence of overturns static instabilities of vertical scale 2 m in the observed density

transport and dynamics of the panay sill overflow in the philippine seas abstract observations of stratification and currents between june 2007 and march 2009 reveal a strong overflow between 400 and 570 m depth from the panay strait into the sulu sea the overflow water is derived from approximately 400 m deep in the south china sea temporal mean velocity is greater than 0 75 m s 1 at 50 m above the 570 m panay sill empirical orthogonal function analysis of a mooring time series shows that the flow is dominated by the bottom overflow current with little seasonal variance the overflow does not descend below 1250 m in the sulu sea but rather settles above high salinity deep water derived from the sulawesi sea the mean observed overflow transport at the sill is 0 32 106 m3 s 1 the observed transport was used to calculate a bulk diapycnal diffusivity of 4 4 10 4 m2 s 1 within the sulu sea slab 575 1250 m ventilated from panay strait analysis of froude number variation across the sill shows that the flow is hydraulically controlled a suitable hydraulic control model

observations of internal wave reflection off sloping bottoms current and temperature spectra exhibit intensification and polarization near sloping bottoms over a band of frequencies centered at the local internal wave critical frequency examples are drawn from a variety of island seamount and continental slope observations waves propagating down from mid depth change energy density wave number and azimuth when they reflect off the bottom providing a natural perturbation to the deep ocean interior internal wave spectrum deviations from linear theory are interpreted as evidence for dissipation through subsequent shear instability and or nonlinear interaction topographic features appear likely to be energy sinks for internal wave energy

the energy flux from the wind to near inertial motions in the surface mixed layer abstract time series of wind stress computed from long term meteorological buoy data off north america are used to examine the forcing of surface inertial currents by the wind a simple damped slab model of the mixed layer is used to compute h the average flux of energy from the wind to mixed layer inertial currents in a mixed layer of fixed depth h the forcing of mixed layer inertial motions is highly intermittent most of the forcing occurs during the winter months with a few dozen events accounting for typically over half the total energy flux major forcing events are usually associated with translating cold fronts or small lows with scales of about 100 km the larger synoptic scale features have little energy at the inertial frequency and thus result in only weak forcing of inertial currents a strong seasonal signal exists in the inertial forcing at ows p 50 n 145 w 50 m is largest from october to february and is a factor of 12 above the june and july values if seasonally varying

geocryological processes linked to high arctic proglacial stream suspended sediment dynamics examples from bylot island nunavut and spitsbergen svalbard recent research has identified differences in processes contributing to suspended sediment concentration ssc dynamics in proglacial streams between high arctic and alpine catchments but does not examine processes explicitly linked to the periglacial environment three glacierized basins were studied austre broggerbreen and midre lov enbreen svalbard 79 n 12 e and glacier b28 unofficially named stagnation glacier bylot island nunavut 73 n 78 w ssc variations were modelled from continuous turbidity discharge and meteorological data throughout the summer months three statistical tools were utilized principal component analysis changepoint analysis and multivariate regression these are shown to be effective in identifying subperiods of distinctive geocryological and glaciofluvial characteristics multivariate regression for the subseasons included autoregressive integrated moving average modelling and showed that ssc variations were related not only to discharge variability but also to fluctuations in energy fluxes the results are interpreted in terms of spatio temporal changes in sediment mobilization and supply associated with changes in the relative importance of fluvial glacial and periglacial processes this evidence supports the notion of important linkages between glacial fluvial and periglacial systems but exemplifies distinct variability between high arctic glaciers copyright 2005 john wiley sons ltd

subharmonic energy transfer from the semidiurnal internal tide to near diurnal motions over kaena ridge hawaii abstractnonlinear energy transfers from the semidiurnal internal tide to high mode near diurnal motions are documented near kaena ridge hawaii an energetic generation site for the baroclinic tide data were collected aboard the research floating instrument platform flip over a 35 day period during the fall of 2002 as part of the hawaii ocean mixing experiment home nearfield program energy transfer terms for a psi resonant interaction at midlatitude are identified and compared to those for near inertial psi close to the m2 critical latitude bispectral techniques are used to demonstrate significant energy transfers in the nearfield between the low mode m2 internal tide and subharmonic waves with frequencies near m2 2 and vertical wavelengths of o 120 m a novel prefilter is used to test the psi wavenumber resonance condition which requires the subharmonic waves to propagate in opposite vertical directions depth time maps of the interactions formed by directly estimating the energy transfer ter

glacier hydrology in svalbard norwegian high arctic abstract progress in glacier hydrology has focused on temperate glaciers although partly or wholly non temperate glaciers are found in many parts of the world and significant areas of former ice sheets were probably non temperate it has usually been assumed that drainage from non temperate glaciers consists of relatively dilute and invariable supraglacial runoff in this paper the hydrology of glaciers in the high arctic archipelago of svalbard is examined variations in the thermal regimes of glaciers and their implications for drainage are first addressed results from svalbard concerning meltwater discharge and storage and solute and suspended sediment dynamics are then reviewed in general meltwater penetration of non temperate ice is limited and drainage from non temperate glaciers in svalbard has many of the characteristics of sub aerial drainage however it would be erroneous to view this drainage simply as dilute supraglacial runoff as significant material transport occurs in suspension and solution furthermore twentieth century climate change has probably led to changes in the thermal regimes of some svalbard glaciers such that relict drainage structures are sometimes observed while meltwater yields are augmented by runoff which can be attributed to the loss of mass from glaciers at large spatial scales turbid plumes observed at the marine margins of polythermal ice caps indicate that meltwater can be routed subglacially through non temperate ice

application of borehole optical televiewing to investigating the 3 d structure of glaciers implications for the formation of longitudinal debris ridges midre lovenbreen svalbard digital optical televiewing optv of hot water drilled boreholes is evaluated as a technique for the investigation of englacial ice and debris structures on the basis of six boreholes drilled in the terminus region of midre lovenbreen svalbard the resulting optv logs successfully reveal several visually distinctive englacial ice properties and deformation structures e g oblique englacial fractures imaged here for the first time combining these optv logs with surface mapping has resulted in the identification of eight separate structural elements several of which can be interpolated onto 3 d grids at a node spacing of 1 m vertically and 10 m horizontally basally derived englacial sediment layers are also found to be intercalated with primary stratification elevated into near vertical planes around a central fold axis by large scale lateral folding the analysis also allows supraglacial longitudinal debris ridges to be subclassified into two types a previously described type i form which are the exposed fold axes of large scale lateral folds and a new type ii form experiencing secondary deformation by small scale horizontal folding in association with vertical displacements across arcuate shear planes in response to longitudinally compressive stresses near the glacier terminus although using boreholes to investigate glacier structure is limited e g by parallelism with vertical planes applying optv to multiple boreholes at midre lovenbreen has successfully revealed a range of 3 d structural elements at high spatial resolution as such interpolating between multiple optv logs overcomes many of the problems associated with interpretations made solely on the basis of surface based structural mapping and combining the two techniques represents a powerful glaciological tool

reduced mixing from the breaking of internal waves in equatorial waters in the oceans heat salt and nutrients are redistributed much more easily within water masses of uniform density than across surfaces separating waters of different densities but the magnitude and distribution of mixing across density surfaces are also important for the earth s climate as well as the concentrations of organisms most of this mixing occurs where internal waves break overturning the density stratification of the ocean and creating patches of turbulence predictions of the rate at which internal waves dissipate were confirmed earlier at mid latitudes here we present observations of temperature and velocity fluctuations in the pacific and atlantic oceans between 42 degrees n and 2 degrees s to extend that result to equatorial regions we find a strong latitude dependence of dissipation in accordance with the predictions in our observations dissipation rates and accompanying mixing across density surfaces near the equator are less than 10 of those at mid latitudes for a similar background of internal waves reduced mixing close to the equator will have to be taken into account in numerical simulations of ocean dynamics for example in climate change experiments

the hydrochemistry of meltwaters draining a polythermal based high arctic glacier south svalbard i the ablation season solute and runoff time series at finsterwalderbreen svalbard provide evidence for considerable basal routing of water and the existence of at least two contrasting subglacial chemical weathering environments the hydrochemistry of a subglacial upwelling provides evidence for a snowmelt fed subglacial reservoir that dominates bulk runoff during recession flow high concentrations of cl and crustal ions high pco2 and ratios of so2 4 so2 4 hco 3 close to 0 5 indicate the passage of snowmelt through a subglacial weathering environment characterized by high rock water ratios prolonged residence times and restricted access to the atmosphere at higher discharges bulk runoff becomes dominated by icemelt from the lower part of the glacier that is conveyed through a chemical weathering environment characterized by low rock water ratios short residence times and free contact with atmospheric gases these observations suggest that icemelt is routed via a hydrological system composed of basal ice marginal englacial and supraglacial components and is directed to the glacier margins by the ice surface slope upwelling water flows relatively independently of icemelt to the terminus via a subglacial drainage system possibly constituting flow through a sediment layer cold basal ice at the terminus forces it to take a subterranean routing in its latter stages the existence of spatially discrete flow paths conveying icemelt and subglacial snowmelt to the terminus may be the norm for polythermal based glaciers on svalbard proglacial mixing of these components to form the bulk meltwaters gives rise to hydrochemical trends that resemble those of warm based glaciers these hydrochemical characteristics of bulk runoff have not been documented on any other glacier on svalbard to date and have significance for understanding interactions between thermal regime and glacier hydrology 1998 john wiley sons ltd

observations of parametric subharmonic instability of the diurnal internal tide in the south china sea 1 shipboard observations are presented that suggest the occurrence of parametric subharmonic instability psi of diurnal k1 and o1 internal tides at critical latitudes of 14 52 n and 13 44 n respectively in a transect spanning 12 5 18 n depth mean shear squared shows sharp peaks at 14 52 n elevated relative to that at 15 n by a factor of ten and at 13 44 n by a factor of 7 wind speed measured from the ship and quikscat scatterometer during and before the transect was 10 m s 1 at these latitudes eight hour time series about 1 6 of an inertial period of shear and isopycnal depth at 14 52 n are sufficient to associate the elevated shear with alternating clockwise rotating layers analogous to those observed at the m2 critical latitude of 28 8 n

turbidity observations in sediment flux studies examples from russian rivers in cold environments turbidity is commonly used as a proxy to estimate suspended sediment content in streams and for hydroecological purposes the scope of this paper is to give an outlook to wider applications of nephelometric turbidimetry as a method uncalibrated turbidity records in conjunction with water chemistry data prove useful in detecting watershed reaction to single hydrological events during the spring flood in arctic russia the turbidimetric survey technique was applied to study the spatial variability of sediment yield features on small rivers of the south eastern part of sakhalin island suspended sediment concentration ssc vs turbidity relation follows the geological features of the terrain and reflects the land use intensity within the watersheds for our igarka key site a logarithmic regression model was developed as an instrument of ssc calculation with turbidity data for each of the four studied watersheds a regional regression model was developed for this site and supplementary water optics data filtered sample turbidity was employed to increase the reliability of ssc calculations our results show that factors influencing turbidity namely water colour and sediment grain size have to be considered in multivariate models to minimize errors and acquire an understanding of what kind of physical response is actually measured by nephelometry based instruments

enhancement of glacial solute fluxes in the proglacial zone of a polythermal glacier annual proglacial solute fluxes and chemical weathering rates at a polythermal high arctic glacier are presented bulk meltwater chemistry and discharge were monitored continuously at gauging stations located at the eastern and western margins of the glacier terminus and at the outlet 2 5 km downstream where meltwaters discharge into the fjord fluxes of non snowpack hco 3 so 4 2 ca 2 and mg 2 increase by 30 47 between the glacier terminus and the outlet indicating that meltwaters are able to access and chemically weather efflorescent sulphates carbonates and sulphides in the proglacial zone smaller increases in the fluxes of non snowpack derived na k and si indicate that proglacial chemical weathering of silicates is less significant en3hanced solute fluxes in the proglacial zone are mainly due to the chemical weathering of active layer sediments the pco 2 of active layer ground waters is above atmospheric pressure this implies that solute acquisition in the active layer involves no drawdown of co 2 the annual proglacial chemical weathering rate in 1999 is calculated to be 2600 meq m 2 this exceeds the chemical weathering rate for the glaciated part of the catchment 790 meq m 2 by a factor of 3 3 hence the proglacial zone at finster walderbreen is identified as an area of high geochemical reactivity and a source of co 2

observations of internal waves and parametric subharmonic instability in the philippines archipelago 1 internal waves contain a significant fraction of the kinetic energy in the ocean and are important intermediaries between the forcing by wind and tide and interior diapycnal mixing we report here on measurements from mindoro strait in the philippines connecting the south china sea to the sulu sea of an internal wave field with a number of surprising properties that point to previously unrecognized processes at work in the region continuum spectral levels are very close to typical background values found in the open ocean but internal tide energy in both the diurnal and semidiurnal frequency bands is significantly elevated and higher at the northern mooring mp1 than the southern mp2 two particularly energetic depth ranges stand out at mp1 an upper layer centered near 300 m and one at the bottom of the water column near 1800 m the upper layer contains both internal tides and a near inertial band with upward and downward propagating waves and an apparent spring neap cycle the combination is suggestive of parametric subharmonic instability as the forcing for the near inertial band a conclusion supported by bicoherence estimates mixing estimated from density overturns is weak over much of the water column but enhanced by about an order of magnitude in the deep layer and closely tied to the internal tide both diurnal and semidiurnal near inertial currents in this deep layer are dominantly rectilinear and not well correlated with the mixing bulk mixing rates at the two sites are less than required to produce property changes seen in hydrography suggesting additional enhancement elsewhere in the archipelago

baroclinic energy flux at the hawaiian ridge observations from the r p flip abstract estimates of baroclinic energy flux are made in the immediate nearfield september october 2002 and 450 km offshore farfield october november 2001 of the kaena ridge an active barotropic to baroclinic conversion site the flux estimates are based on repeated profiles of velocity and density obtained from the research platform floating instrument platform flip as an aspect of the hawaii ocean mixing experiment energetic beams associated with both semidiurnal and diurnal internal waves are observed in the kauai channel beam depths and orientations are consistent with generation along the upper flanks of the ridge at the far field site the baroclinic energy flux is borne primarily by first mode semidiurnal waves the energy flux associated with the entire spectrum of internal waves is computed by cross spectral analysis significant energy fluxes are found in the inertial diurnal semidiurnal and twice semidiurnal frequency bands the semidiurnal energy flux strongly dominates the s

fluvial suspended sediment yields over hours to millennia in the high arctic at proglacial lake linnevatnet svalbard sediment yield can be a sensitive indicator of catchment dynamics and environmental change for a glacierized catchment in the high arctic we compiled and analyzed diverse sediment transfer data spanning a wide range of temporal scales to quantify catchment yields and explore landscape response to past and ongoing hydroclimatic variability the dataset integrates rates of lake sedimentation from correlated varve records and repeated annual and seasonal sediment traps augmented by multi year lake and fluvial monitoring consistent spatial patterns of deposition enabled reconstruction of catchment yields from varve and trap based fluxes we used hydroclimatic data and multivariate modeling to examine annual controls of sediment delivery over almost a century and to examine shorter term controls of sediment transfer during peak glacier melt particle size analyses especially for annual sediment traps were used to further infer sediment transfer mechanisms and timing through the medieval warm period and little ice age there were no apparent multi century trends in lake sedimentation rates which were over three times greater than those during the mid holocene when glaciers were diminished twentieth century sedimentation rates were greater than those of previous millennia with a mid century step increase in mean yield from 240 to 425 mg km 2 yr 1 annual yields through the twentieth century showed significant positive relations with spring summer temperature rainfall and peak discharge conditions this finding is significant for the future of sediment transfer at linnevatnet and perhaps more broadly in the arctic where continued increases in temperature and rainfall are projected for 2004 2010 annual yields ranged from 294 to 1330 mg km 2 yr 1 sediment trap volumes and particle size variations indicate that recent annual yields were largely dominated by spring to early summer transfer of relatively coarse grained sediment fluvial monitoring showed daily to hourly sediment transfer to be related to current and prior discharge diurnal hysteresis air temperature and precipitation

observations of near inertial internal gravity waves radiating from a frontal jet abstractshipboard adcp and towed ctd measurements are presented of a near inertial internal gravity wave radiating away from a zonal jet associated with the subtropical front in the north pacific three dimensional spatial surveys indicate persistent alternating shear layers sloping downward and equatorward from the front as a result depth integrated ageostrophic shear increases sharply equatorward of the front the layers have a vertical wavelength of about 250 m and a slope consistent with a wave of frequency 1 01f they extend at least 100 km south of the front time series confirm that the shear is associated with a downward propagating near inertial wave with frequency within 20 of f a slab mixed layer model forced with shipboard and ncep reanalysis winds suggests that wind forcing was too weak to generate the wave likewise trapping of the near inertial motions at the low vorticity edge of the front can be ruled out because of the extension of the features well south of it instead the authors

a composite spectrum of vertical shear in the upper ocean abstract results from three separate velocity profilers operated nearly simultaneously in the northwest atlantic in 1975 are used to form a composite shear spectrum over vertical wavelengths from 100 m down to a few centimeters this exercise constitutes an intercomparison of the three different measurement techniques and reveals a shear spectrum which is approximately fiat at a wkb scaled level from k 0 01 cpm through k0 0 1 cpm then falls as k 1 to a buoyancy wavenumber k0 n3 1 2 determined by the local average vaisala frequency n and the volume averaged dissipation rate various consequences of the observed shear spectral shape are explored

global abyssal mixing inferred from lowered adcp shear and ctd strain profiles abstract internal wave wave interaction theories and observations support a parameterization for the turbulent dissipation rate e and eddy diffusivity k that depends on internal wave shear vz2 and strain z2 variances its latest incarnation is applied to about 3500 lowered adcp ctd profiles from the indian pacific north atlantic and southern oceans inferred diffusivities k are functions of latitude and depth ranging from 0 03 10 4 m2 s 1 within 2 of the equator to 0 4 0 5 10 4 m2 s 1 at 50 70 diffusivities k also increase with depth in tropical and subtropical waters diffusivities below 4500 m depth exhibit a peak of 0 7 10 4 m2 s 1 between 20 and 30 latitudes where semidiurnal parametric subharmonic instability is expected to be active turbulence is highly heterogeneous though the bulk of the vertically integrated dissipation e is contributed from the main pycnocline hotspots in e show some correlation with small scale bottom roughness and near bottom flow at sites where st

structure propagation and mixing of energetic baroclinic tides in mamala bay oahu hawaii abstract large semidiurnal vertical displacements 100 m and strong baroclinic currents 0 5 m s 1 several times as large as barotropic currents dominate motions in mamala bay outside the mouth of pearl harbor hawaii during september 2002 the authors sought to characterize them with a 2 month mclane moored profiler deployment and a 4 day intensive survey with a towed ctd adcp and the research vessel r v revelle hydrographic sonar spatial maps and time series of turbulent dissipation rate diapycnal diffusivity k isopycnal displacement velocity u energy e and energy flux f are presented dissipation rate peaks in the lower 150 m during rising isopycnals and high strain and shows a factor of 50 spring neap modulation the largest k values in the western bay near a submarine ridge exceed 10 3 m2 s 1 the m2 phases of and u increase toward the west implying a westward phase velocity cp 1 m s 1 and horizontal wavelength 60 km consistent with theoretical mode 1 values these phase

energy flux and dissipation in luzon strait two tales of two ridges abstractinternal tide generation propagation and dissipation are investigated in luzon strait a system of two quasi parallel ridges situated between taiwan and the philippines two profiling moorings deployed for about 20 days and a set of nineteen 36 h lowered adcp ctd time series stations allowed separate measurement of diurnal and semidiurnal internal tide signals measurements were concentrated on a northern line where the ridge spacing was approximately equal to the mode 1 wavelength for semidiurnal motions and a southern line where the spacing was approximately two thirds that the authors contrast the two sites to emphasize the potential importance of resonance between generation sites throughout luzon strait baroclinic energy energy fluxes and turbulent dissipation were some of the strongest ever measured peak to peak baroclinic velocity and vertical displacements often exceeded 2 m s 1 and 300 m respectively energy fluxes exceeding 60 kw m 1 were measured at spring tide at the wester

glacial hydrological system characterization using ground penetrating radar hydrological systems near the terminus of a high arctic glacier and a proglacial icing on bylot island canada were investigated using ground penetrating radar gpr the ice thickness and the location and depth of tunnels within the glacier and icing were imaged modelling of the gpr response was utilized to predict the data quality and to assist in its interpretation the unique properties of the ice enabled velocity determinations from the diffraction patterns generated by point source reflectors as well as traditional velocity surveys the propagation velocity of the radar pulses through the ice depended on the air and water content in the ice the identification of drainage tunnels was attained through pulse polarity analysis and interpolation between the profiles in gridded surveys it was found that reflectivity analysis may enable gpr to be used for acquiring three dimensional information on the thermal structure of glaciers the much more complicated structure of the icing was imaged with higher frequency antennae and it was found that general ice types could be mapped using radar stratigraphical analysis both buried slush mounds and subsurface channel fills were identified within the icing a portion of the icing near the centre of the valley floor that has persisted perennially for over 50 years was found to be sitting on a slightly higher area of the valley bottom and thus was not subjected to the same hydrothermal erosional forces as the edges of the icing setting up a feed back loop encouraging the preservation of the central core of ice and promoting the destruction and rebuilding of the edges every year

the thermal regime of sub polar glaciers mapped by multi frequency radio echo sounding radio echo soundings provide an effective tool for mapping the thermal regimes of polythermal glaciers on a regional scale radar signals of 320 370 mhz penetrate ice at sub freezing temperatures but are reflected from the top of layers of ice which are at the melting point and contain water radar signals of 5 20 mhz on the other hand see through both the cold and the temperate ice down to the glacier bed radio echo soundings at these frequencies have been used to investigate the thermal regimes of four polythermal glaciers in svalbard kongsvegen uversbreen midre lovenbreen and austre broggerbreen in the ablation area of kongsvegen a cold surface layer 50 160m thick was underlain by a warm basal layer which is advected from the temperate accumulation area the surface ablation of this cold layer may be compensated by freezing at its lower cold temperate interface this requires that the free water content in the ice at the freezing interface is about 1 of the volume the cold surface layer is thicker beneath medial moraines and where cold based hanging glaciers enter the main ice stream on uversbreen the thermal regime was similar to that of kongsvegen a temperate hole was found in the otherwise cold surface layer of the ablation area in a surface depression between kongsvegen and uversbreen where meltwater accumulates during the summer near the subglacial lake setevatnet 250 m a s l lovenbreen was frozen to the bed at the snout and along all the mountain slopes but beneath the central part of the glacier a warm basal layer up to 50m thick was fed by temperate ice from two cirques on austre broggerbreen a temperate basal layer was not detected by radio echo soundings but the basal ice was observed to be at the melting point in two boreholes

pyrite replacement of mollusc shells from the lower oxford clay jurassic of england replacement of originally aragonite mollusc shells by pyrite commonly occurs in the lower oxford clay petrographic studies show the shells to have constituted complex microenvironments in the sediment a range of replacement textures is found showing a variable amount of solution of the original aragonite three distinct textures were found in crushed pyrite replaced ammonite shells from heavily pyritized concretions 1 a texture reflecting the original shell structure due to the replacement of the organic shell matrix by pyrite 2 an ovoid texture seen at several stages of replacement reflecting processes occurring at discrete centres of sulphate reduction 3 euhedral crystals lining cracks and fractures in the shell three types of replacement are found in small gastropods and bivalves from shell bed some of which may relate to those seen in the ammonites 1 replacement of organic shell matrix by pyrite preserving good shell microstructure 2 replacement showing outwardly good preservation of morphological features but inwardly only the gross structure such as growth lines is preserved 3 replacement of the shell in a matrix of euhedral pyrite leaving only lines of carbonate inclusions marking the margins of the shell the replacement textures and types appear to be dependent on the initial structure of the shell and the access of iron and sulphate into the shell early stages of replacement appear to proceed by pyrite formation within the organic matrix of the shell with little or no solution of the carbonate this produces textures which faithfully mimic the original shell microstructure it is thought that the lack of carbonate solution is due to a limited availability of iron brought about by the less intensively reducing nature of the sediment later stages of replacement are promoted by the cracking and fracturing of the shell and are generally not as faithful to the original shell structure this is due to the greater availability of iron as the sediment becomes more reducing with burial

analysis and interpretation of patterns within and between hydroclimatological time series in an alpine glacier basin this paper explores patterns within and between climatological and hydrological time series from an alpine glacier basin time series recorded in the basin of the haut glacier d arolla over the 1989 ablation season are subdivided into five subperiods box jenkins arima autoregressive integrated moving average and tfn transfer function noise models are estimated for each of the five subperiods and differences between the models are interpreted in the context of changing glacier hydrology particularly the changing nature and extent of the glacier drainage network

subtropical catastrophe significant loss of low mode tidal energy at 28 9 1 an idealized numerical study of a northward propagating internal tide reveals a dramatic loss of energy to small scale subharmonic instabilities near 28 9 n inspired by observations of the internal tide radiating northward from the hawaiian ridge a three dimensional numerical model is initialized with a northward baroclinic tidal flux of approximately 1 7 kw m after an initial spinup period energy is quickly transferred from the baroclinic tide to subharmonic motions with half the horizontal tidal wavenumber and small vertical scales through nonlinear advection of horizontal tidal velocity gradients potential oceanic implications are twofold first once a steady state has been reached the instability acts as a partial filter of northward tidal flux between 27 5 and 29 5 n in rough agreement with some altimetric tidal observations second elevated shear of the subharmonic motions suggests the potential for elevated near surface dissipation rates near the critical latitude that may be important for upper ocean mixing

internal tides in monterey submarine canyon abstract the m2 internal tide in monterey submarine canyon is simulated using a modified version of the princeton ocean model most of the internal tide energy entering the canyon is generated to the south on sur slope and at the head of carmel canyon the internal tide is topographically steered around the large canyon meanders depth integrated baroclinic energy fluxes are up canyon and largest near the canyon axis up to 1 5 kw m 1 at the mouth of the upper canyon and increasing to over 4 kw m 1 around monterey and san gregorio meanders the up canyon energy flux is bottom intensified suggesting that topographic focusing occurs net along canyon energy flux decreases almost monotonically from 9 mw at the canyon mouth to 1 mw at gooseneck meander implying that high levels of internal tide dissipation occur the depth integrated energy flux across the 200 m isobath is order 10 w m 1 along the majority of the canyon rim but increases by over an order of magnitude near the canyon head where internal ti

short term discharge and suspended sediment fluctuations in the proglacial skeldal river north east greenland the summer discharge pattern of the skeldal river which drains a 560 km2 partly glacierized catchment in north east greenland is dominated by diurnal oscillations reflecting variations in the melt rate of snow and ice in the basin superimposed on this diurnal pattern are numerous short lived discharge fluctuations of irregular periodicity and magnitude the larger fluctuations are described and attributed to both rainfall events and periodic collapse of the glacier margin damming flow from beneath the skelbrae glacier other minor fluctuations are less readily explained but are associated with changes in the channelized and distributed reservoirs and possibly temporary blockage of subglacial conduits caused by ice melt with subsequent damming fluctuations in suspended sediment concentration ssc are normally associated with discharge fluctuations although examples of transient flushes were observed where marked increases in ssc occurred in the absence of corresponding discharge variations a strong relationship between the event discharge increase and event ssc increase for rainfall induced events was established but no such relationship existed for non rainfall induced events there is some evidence for an exhaustion effect in the ssc patterns both at the event time scale and as the month proceeds a mean suspended sediment load of 1765 0 26 t day 1 was estimated for the study period which would be equivalent to a suspended sediment yield of 732 4 t km 2 year 1 copyright 2001 john wiley sons ltd

propagation of low mode internal waves through the ocean abstract the baroclinic tides play a significant role in the energy budget of the abyssal ocean although the basic principles of generation and propagation are known a clear understanding of these phenomena in the complex ocean environment is only now emerging to advance this effort a ray model is developed that quantifies the effects of spatially variable topography stratification and planetary vorticity on the horizontal propagation of internal gravity modes the objective is to identify baroclinic shoals where wave energy is spatially concentrated and enhanced dissipation might be expected the model is then extended to investigate the propagation of internal waves through a barotropic mesoscale current field the refraction of tidally generated internal waves at the hawaiian ridge is examined using an ensemble of mesoscale background realizations derived from weekly ocean topography experiment topex poseidon altimetric measurements the path of mode 1 is only slightly affected by typical cur

the hydrochemistry of bayelva a high arctic proglacial stream in svalbard major ion silica and ph data from a high arctic proglacial stream network are examined factor analysis shows that the major controls upon hydrochemistry in the basin include snowpack solute elution rapid alteration of minerals via surface reactions and slow incongruent silicate dissolution the importance of chemical weathering is found to increase downstream at the expense of solute acquisition from the transient snowpack data from a series of snow pits show that snowpack solute elution is characterised by the preferential elution of so42 evidence for the preferential elution of no3 is equivocal however no3 levels in proglacial runoff may be enhanced by the leaching of cryotic soils later in the ablation season chemical weathering is dominated by calcite dissolution at high elevations and a combination of calcite and dolomite dissolution in the downstream proglacial environment silicate weathering at high elevations is characterised by the enrichment of k relative to si concentrated active layer soil waters show less enrichment of k and constitute a potentially important source of dissolved silica to the river system na is also produced by silicate weathering but its mobility is believed to be largely governed by ion exchange with ca2 early in the ablation season all chemical weathering environments are characterised by high p co2 due to either respiration within the soil or at higher elevations within the catchment h provision from acid aerosol and sulphide oxidation however rates of sulphide oxidation are limited because the cold based thermal regime of the glaciers effectively prevents access of meltwaters to freshly comminuted sub glacial sulphide minerals the restricted sub glacial weathering therefore means that ice marginal and proglacial environments are the most important zones of solute acquisition by meltwaters causing significant enrichment of major ions silica and dissolved co2 within only a short distance of the contemporary ice margin

links between proglacial stream suspended sediment dynamics glacier hydrology and glacier motion at midtdalsbreen norway two hourly suspended sediment concentration variations observed during the summer of 1987 in the proglacial stream draining midtdalsbreen norway are modelled using multiple regression and time series techniques suspended sediment fluctuations are influenced by stream discharge variations diurnal hysteresis effects medium term sediment supply and transport variations and the recent suspended sediment concentration history of the stream they do not appear to be influenced by seasonal exhaustion or rainfall variations possible reasons for this are discussed large positive residuals from the fitted models are major pulses of suspended sediment unrelated to discharge variations these sediment flushes correlate with periods of enhanced glacier motion they cannot be explained by enhanced sediment production by subglacial erosion but are probably due to the tapping of subglacially stored sediment during sudden changes in the hydraulics and or configuration of the subglacial hydrological system seasonal changes in the lag between glacier motion peaks and suspended sediment flushes suggest that the subglacial hydrological system evolves over the summer from a distributed to a more channelized configuration

suspended sediment yield and transfer processes in a small high arctic glacier basin svalbard observations of suspended sediment concentration and discharge at two sites on the proglacial river network draining from a predominantly cold based high arctic glacier austre broggerbreen are described analysis of these observations illustrates i the relatively low suspended sediment yield from this basin in comparison with many other glacier basins reported in the open literature ii sustained and possibly increasing availability of suspended sediment to the fluvial system as the ablation season progresses and iii the role of the proglacial sandur as both a sediment source and sink field observations coupled with the results of the data analysis are used to make inferences concerning the changing nature and relative importance of sediment sources within the basin 1998 john wiley sons ltd

glacier meltwater hydrochemistry abstract glacierised areas present an ideal environment in which to study water rock interaction since chemical weathering rates are high and anthropogenic impacts are often minimal detailed investigations of meltwater quality variations have suggested the importance of these environments in estimates of terrestrial chemical erosion and global biogeochemical cycles most notably the role of meltwaters in co2 sequestration during episodes of deglaciation has attracted considerable attention since this may impact on climate at glacial interglacial timescales however there is still considerable uncertainty surrounding estimates of co2 drawdown by meltwaters which remains to be resolved water flow through glaciers exerts an important control on ice mass dynamics and influences the quantity and quality of water delivered to environments downstream of glacierised basins thus the study of the configuration and dynamics of subglacial drainage systems is important not only to enhance scientific understanding but also to allow effective water resource utilisation in glacierised headwater catchments bulk meltwater quality characteristics draining terrestrial ice masses also offer the potential to provide unique information on hydrological and hydrochemical processes operating in the inaccessible subglacial environment here significant advances have been made in understanding the controls on chemical weathering reactions based on the identification of key dissolved indicator species this has allowed water quality variations to be exploited as a tool for both subglacial hydrochemical and hydrological investigations as a result this area of glaciology has received considerable attention in recent years utilising an increasing range of dissolved ions and integrating field and laboratory studies however uncertainty still surrounds certain areas of meltwater quality science including the role of microorganisms in a system which to date has largely been viewed as abiotic a better understanding of the processes and rates of chemical weathering in glacierised environments has the potential to enhance our understanding of the environment and to facilitate the exploitation of water quality variations for both scientific and applied objectives in this paper the development and current state of meltwater quality science as a tool for investigating subglacial hydrology and geochemistry is detailed and problems and future directions identified this will hopefully stimulate wider interest in an important area of aquatic chemistry with significant applied implications

fluvial suspended sediment transport from cold and warm based glaciers in svalbard an analysis of temporal variability in proglacial suspended sediment concentration is undertaken using time series data collected from three svalbard basins which include one largely cold based glacier austre broggerbreen one largely warm based glacier finsterwalderbreen and one intermediate polythermal glacier erdmannbreen the temporal variability in proglacial suspended sediment concentration is analysed using multiple regression techniques in which discharge is supplemented by other predictors acting as surrogates for variability in sediment supply at diurnal medium term and seasonal timescales these multiple regression models improve upon the statistical explanation of suspended sediment concentration produced by simple sediment rating curves but need to account for additional stochastic elements within the time series before they may be considered successful an interpretation of the physical processes which are responsible for the regression model characteristics is offered as a basis for comparing the different arctic glaciofluvial suspended sediment transport systems with that of their better known temperate glaciofluvial counterparts it is inferred that the largely warm based glacier is dominated by sediment supply from subglacial reservoirs which evolve in a similar manner to temperate glaciers and which cause a pronounced seasonal exhaustion of suspended sediment supply the largely cold based glacier however is dominated by sediment supply from marginal sources which generate a responsive system at short time scales but no significant seasonal pattern the intermediate polythermal glacier basin which was anticipated to be similar to the warm based glacier instead shows a highly significant seasonal increase in suspended sediment supply from an unusual subglacial reservoir emerging under pressure in the glacier foreland the temperate model of glaciofluvial suspended sediment transport is therefore found to be of limited use in an arctic context copyright 1999 john wiley sons ltd

changes in geometry and subglacial drainage of midre lovenbreen svalbard determined from digital elevation models digital elevation models dems of the bed and surface of the polythermal midre lovenbreen svalbard are used to identify changes in glacier geometry between 1977 and 1995 the calculated mean annual mass balance 0 61 m water equivalent w e a 1 is more negative than that derived from field measurements 0 35 m w e a 1 although the error associated with this value 0 7 m a 1 suggests that the difference may be accounted for by errors however similar discrepancies between dem based and field based measurements of mass balance have been reported elsewhere in svalbard although errors may be responsible patterns of surface elevation change may also be explained in terms of patterns of ablation accumulation and dynamics the theoretical structure of the subglacial drainage system is modelled using different assumptions about subglacial water pressure in 1977 and 1995 these reconstructions are compared with the observed positions of proglacial outlet streams decreasing subglacial water pressure results in a decrease in the influence of surface morphology and an increase in the role of the bed topography on drainage routing which generally leads to more dispersed drainage long term changes in the position of proglacial outlet streams occur as a result of changes in glacier geometry but short term changes may also occur in response to early season water pressures controlled by meteorological and hydrological conditions copyright 2003 john wiley sons ltd