a minimum sample size required from schmidt hammer measurements the schmidt hammer is a useful tool applied by geomorphologists to measure rock strength in field conditions the essence of field application is to obtain a sufficiently large dataset of individual rebound values which yields a meaningful numerical value of mean strength although there is general agreement that a certain minimum sample size is required to proceed with the statistics the choice of size i e number of individual impacts was usually intuitive and arbitrary in this paper we show a simple statistical method based on the two sample student s t test to objectively estimate the minimum number of rebound measurements we present the results as 1 the mean and median solutions each providing a single estimate value and 2 the empirical probability distribution of such estimates based on many field samples schmidt hammer data for 14 lithologies 13 81 samples for each with each sample consisting of 40 individual readings have been evaluated assuming different significance levels the principal recommendations are 1 the recommended minimum sample size for weak and moderately strong rock is 25 2 a sample size of 15 is sufficient for sandstones and shales 3 strong and coarse rocks require 30 readings at a site 4 the minimum sample size may be reduced by one third if the context of research allows for higher significance level for test statistics interpretations based on less than 10 readings from a site should definitely be avoided copyright 2009 john wiley sons ltd

numerical simulations of tropical cyclone ocean interaction with a high resolution coupled model the tropical cyclone ocean interaction was investigated using a high resolution tropical cyclone ocean coupled model the model design consisted of the noaa geophysical fluid dynamics laboratory tropical cyclone prediction model which was coupled with a multilayer primitive equation ocean model coupling between the hurricane and the ocean models was carried out by passing into the ocean model the wind stress heat and moisture fluxes computed in the hurricane model the new sea surface temperature sst calculated by the ocean model was then used in the tropical cyclone model a set of idealized numerical experiments were performed in which a tropical cyclone vortex was embedded in both easterly and westerly basic flows of 2 5 5 and 7 5 m s 1 with a fourth experiment run with no basic flow specified initially the profile of the tangential wind for hurricane gloria at 1200 utc 22 september 1985 was used as the initial condition of the tropical cyclone for each of the experiments the model ocean was initially horizontally homogenous and quiescent to clarify the impact of the ocean response to the hurricane s behavior analogous experiments were also carried out with the sst kept constant control cases the experiments indicated that the cooling of the sea surface induced by the tropical cyclone resulted in a significant impact on the ultimate storm intensity due to the reduction of total heat flux directed into the tropical cyclone above the regions of decreased sst the sea surface cooling produced by the tropical cyclones was found to be larger when the storms moved slower in the experiments run without an initial basic flow the maximum sst anomaly was about 5 6 c with a resulting difference in the minimum sea level pressure and maximum surface winds of 16 4 hpa and 7 m s 1 respectively in contrast in the experiments run with the 7 5 m s 1 basic flow the maximum sst anomalies ranged from about 2 6 to 3 0 c with a difference in the minimum sea level pressure and maximum surface winds of about 7 3 hpa and 2 7 m s 1 the tropical cyclone ocean coupling significantly influenced the storm track only for the case with no basic flow and the 2 5 m s 1 easterly flow in these cases the storm with the ocean interaction turned more to the north and east no basic flow or the north 2 5 m s 1 easterly flow of the experiments with constant sst in the first case the storm by 72 hours was located over 70 km to the east southeast of the control case a possible explanation for this track deviation is related to a systematic weakening of the mean tangential flow at all radii of the storm due to the interaction with the ocean and resulting alteration of the beta drift

a numerical study of the effect of island terrain on tropical cyclones abstract a triply nested movable mesh model was used to study the behavior of tropical cyclones encountering island mountain ranges the integration domain consisted of a 37 wide and 45 long channel with an innermost mesh resolution of 1 6 the storms used for this study were embedded in easterly flows of 5 and 10 m s 1 initially realistic distributions of island topography at 1 6 resolution were inserted into the model domain for the region of the caribbean including the islands of cuba hispaniola and puerto rico the island of taiwan and the region of luzon in the northern philippines it was found that the islands affected the basic flow as well as the wind field directly associated with the storm system the combination of these effects caused changes in the track and translational speed of the storm in particular in the case of the 5 m s 1 easterly flow the storm accelerated and veered to the north well before reaching taiwan for the other island distributions the northward deflecti

hurricane generated currents on the outer continental shelf 1 model formulation and verification a numerical model is developed to simulate currents generated by hurricanes on the outer continental shelf and slope emphasis is on the mixed layer response within a few hours of storm passage however some attention is given to the lower layer and shelf wave responses the model is based on a layered explicit finite difference formulation using the nonlinear primitive equations including conservation of heat the problem of topography intersecting the model layer is resolved by introducing artificial steps of the order of 100 m where the layer intersects the slope model comparisons are presented for three gulf of mexico hurricanes using a 0 2 grid for two of the storms the model reproduces better than 80 of the observed velocity variance with correlation coefficients of greater than 0 8 for the mixed layer discrepancies in the comparisons are traced to unresolved local topography and nonstorm forcing such as warm core rings further model simulations reveal that 1 substantial shelf waves were generated with phase speeds of 4 to 10 m s 1 2 the response is primarily baroclinic even in water as shallow as 200 m 3 an entrainment law which scales with the velocity difference between the mixed layer and upper thermocline yields markedly better comparisons than one which scales with the wind stress and 4 deviations from a straight line storm path can significantly alter the response

satellite measurements of sea surface cooling during hurricane gloria hurricanes and other strong storms can cause important decreases in sea surface temperature by means of vertical mixing within the upper ocean and by air sea heat exchange here we use satellite derived infrared images of the western north atlantic to study sea surface cooling caused by hurricane gloria 1985 significant regional variations in sea surface cooling are well correlated with hydrographic conditions the greatest cooling up to 5 c occurred in slope waters north of the gulf stream where the seasonal thermocline is shallowest and most compressed moderate cooling up to 3 c occurred in the open sargasso sea where the thermocline is deeper and more diffused little or no cooling occurred in shallow coastal waters bottom depth less than 20 m which were isothermal before the passage of hurricane gloria there is a pronounced right side asymmetry of sea surface cooling with stronger by a factor of 4 and more extensive by a factor of 3 cooling found on the right side of the hurricane track these qualitative results are consistent with the notion that vertical mixing within the upper ocean is the dominant sea surface cooling mechanism of hurricanes

ocean response to a hurricane part i observations abstract the response of the ocean to hurricanes was investigated using aircraft deployable expendable current profilers axcp the goals were to observe and separate the surface wave and surface mixed layer sml velocities under the storms and to map the across track and along track velocity and temperature response in the mixed layer and thermocline custom instrumentation was prepared including slower failing axcps and the axcp equipment was installed on noaa wp 3d aircraft research flights were made into two 1984 hurricanes norbert in the eastern pacific off baja california 19 n 109 w and josephine off the east coast of the united states 29 n 72 w thirty one probes were deployed in each hurricane and about half the axcps provided temperature and velocity profiles most velocity profiles exhibited strong surface wave contributions slablike velocities in the sml strong shears beneath the sml and only weak flows in the upper thermocline separation of the surface gravity wave velociti

a coupled atmosphere wave ocean modeling system simulation of the intensity of an idealized tropical cyclone abstract a coupled atmosphere wave ocean modeling system cawoms based on the integration of atmosphere wave atmosphere ocean and wave current interaction processes is developed the component models consist of the weather research and forecasting wrf model the simulating waves nearshore swan model and the princeton ocean model pom the coupling between the model components is implemented by using the model coupling toolkit the cawoms takes into account various wave related effects including wave state and sea spray affected sea surface roughness sea spray heat fluxes and dissipative heating in atmosphere wave coupling it also considers oceanic effects such as the feedback of sea surface temperature sst cooling and the impact of sea surface current on wind stress in atmosphere ocean coupling in addition wave current interactions including radiation stress and wave induced bottom stress are also taken into account the cawoms is applied to the simulation of an idealized tropical cyclo

new ways of studying ice sheet flow directions and glacial erosion by computer modelling examples from fennoscandia a computer ice sheet model has been used to study regional ice flow directions and glacial erosion of the weichselian ice sheet adopting a new method of presenting modelled ice flow directions ice sheet model results from different time periods during the weichselian were extracted for five regions and presented in rose diagrams when comparing these computer generated results with information on flow directions obtained from current conceptual geological models based on field data large similarities were observed in comparing the ice flow directions as such the similarities were strikingly good in many cases there was also a good agreement in the timing of the events while in some cases a certain flow direction was assigned to a different time period by the ice sheet model than in the current interpretation of geological information nevertheless the overall agreement between the data sets shows that results from ice sheet models can aid in placing geological information into a coarse timeframe and chronostratigraphic context and also fill in time gaps in the glacial geological record where chronological control is sparse ice sheet model results thus constitute a new data set against which glacial geological information can be compared and tested a new quantity basal sliding distance has also been calculated from the ice sheet model results describing the over time accumulated length of ice that has passed over the landscape by basal sliding the results show high basal sliding distance values in sw sweden se norway in skagerrak and along the gulf of bothnia implying relatively large amounts of glacial erosion in these regions on elevated parts of the scandinavian mountain range and on adjacent plains in the east the basal sliding distance values are low implying weaker glacial erosion this compares well with different types of geological and morphological data suggesting that basal sliding distance is a useful entity for studying regional patterns of glacial erosion intensity

measurement and calibration of weathering using the schmidt hammer on wave washed moraines on the upper norrland coast sweden the schmidt hammer has for some years been used to measure the hardness of different rock surfaces and to date relatively boulders in moraine deposits in this paper applications on isostatically raised boulder beaches and rocky shores are described the research area is the northern swedish bothnian coast where present isostatic uplift is between 0 8 1 0 cm year 1 elevations above sea level can be converted to a timescale rebound values r of the schmidt hammer are correlated with the altitude and the degree of rock weathering can be estimated for each site eight sites with boulder beaches and nine sites with rocky shores have been analysed for boulder beaches correlation coefficients of 0 82 0 97 for weathering values r and the elevations above sea level were obtained for the rocky shores these values were calculated to 0 75 0 97 this method has applications in both geomorphology and archaeology for example a deep layer of weathered dolerite in the nordingra region which previously has been regarded as a post weichselian formation can be shown to be of pre weichselian origin several archaeological applications are also mentioned in the paper

prediction experiments of hurricane gloria 1985 using a multiply nested movable mesh model abstract the prediction capability of the gfdl triply nested movable mesh model with finest grid resolution of degree was investigated using several case studies of hurricane gloria 1985 during the period that the storm approached and moved up the east coast of the united states the initial conditions for these experiments were interpolated from an nmc t80 global analysis at 0000 utc 25 september and 1200 utc 22 september the integrations starting from 0000 utc 25 september were run 72 h while those starting on 1200 utc 22 september were run 132 h the lateral boundary conditions were obtained from either an integration of the nmc t80 forecast model or the t80 global analysis or were fixed to the initial value the model s predicted track of gloria for each integration was compared against the best track determined by the national hurricane center nhc for the case starting from 0000 utc 25 september using a forecasted boundary condition the model successfully forecasted significant acceler

geomorphological surfaces of different age and origin in granite landscapes an evaluation of the schmidt hammer test granite landforms in sierra nevada california and the southern part of sweden were used to test whether a schmidt hammer can be used to distinguish surfaces of different age and origin based on 3260 readings statistically signi cant differences were obtained from surfaces formed and or affected by different geomorphological processes aeolian uvial or glacially polished surfaces yield higher values than surfaces exposed to surface weathering which are distinguishable from surfaces at a weathering front caused by deep weathering copyright 2004 john wiley sons ltd

the schmidt hammer as a relative age dating tool and its potential for calibrated age dating in holocene glaciated environments the schmidt hammer is a relatively cheap portable sturdy instrument with proven value over the last two decades or so in rapidly dating coarse inorganic deposits of diverse origins early views were that its dating role was limited to distinguishing recently exposed from much older typically either a few sites of possibly different ages or occasional older surfaces amongst many young sites were studied more recently calibration curves based on individual r value means from small numbers 2 4 of sites of known ages have been used to estimate the ages of undated sites we present schmidt hammer rebound r values from 28 little ice age and younger 23 preboreal and 7 younger dryas glaciated surfaces in southern norway in order first to test rigorously the robustness of the instrument as a relative age dating tool despite being obtained from different surfaces moraines glaciofluvial deposits and bedrock and varied metamorphic lithologies the r value overall means and 95 confidence intervals for the little ice age preboreal and younger dryas age categories respectively 60 0 1 6 41 6 1 4 and 34 2 2 0 are statistically significantly different only two outlying sites in the two younger age categories have overlapping confidence intervals demonstrating remarkable robustness in differentiating early and late holocene surfaces the distinction between preboreal and younger dryas sites with terminal dates 2000 years apart is less clear but still statistically significant though possibly partly because of enhanced weathering conditions at the predominantly well vegetated younger dryas sites second we examine the feasibility and desirability of controlling non age related factors including some previously considered critical instrument wear operator bias initial rock surface texture which emerge either as less important than previously argued or as relatively unimportant together with others previously unreported e g long term changes in lichen soil snow and vegetation covers third we investigate the potential for calibrated age dating by applying exploratory linear rates of r value decline to selected combinations of sites the results suggest that error limits of ca 700 to 1600 years should be achievable over the holocene timescale this improved dating capability however will require adequate numbers of site means not only for each age category used to define these curves but also for each set of test surfaces of the same ages recommendations are made for a suitable sampling protocol for developing further the schmidt hammer as a calibrated age dating tool

diagnosing forecast errors in tropical cyclone motion abstractthis paper reports on the development of a diagnostic approach that can be used to examine the sources of numerical model forecast error that contribute to degraded tropical cyclone tc motion forecasts tropical cyclone motion forecasts depend upon skillful prediction of the environment wind field and by extension the synoptic scale weather systems nearby the tc while previous research suggests that the deep layer mean dlm steering flow typically approximates the actual tc motion it is shown that the motion of even mature tcs can depart from the dlm steering flow an optimal environmental steering flow is defined which varies the vertical extent of the steering layer and the radius over which tc vorticity and divergence are removed errors in predicted tc motion are quantified using a diagnostic equation that accounts for not only differences in the synoptic scale flow but also differences in the depth and radius used to define the steering flow differences in the latter two parameters a

satellite derived ocean thermal structure for the north atlantic hurricane season abstractthis paper describes a new model method called satellite derived north atlantic profiles snap that seeks to provide a high resolution near real time ocean thermal field to aid tropical cyclone tc forecasting using about 139 000 observed temperature profiles a spatially dependent regression model is developed for the north atlantic ocean during hurricane season a new step introduced in this work is that the daily mixed layer depth is derived from the output of a one dimensional price weller pinkel ocean mixed layer model with time dependent surface forcing the accuracy of snap is assessed by comparison to 19 076 independent argo profiles from the hurricane seasons of 2011 and 2013 the rms differences of the snap estimated isotherm depths are found to be 10 25 m for upper thermocline isotherms 29 19 c 35 55 m for middle isotherms 18 7 c and 60 100 m for lower isotherms 6 4 c the primary error sources include uncertainty of sea surface height anomaly ssha high frequency fluc

current and density observations across the wake of hurricane gay abstract ctd and acoustic doppler current profiler data are analyzed for the response of the upper ocean to rapidly moving hurricane gay currents were observed within about two days of the hurricane passage and were dominated by a blue shifted inertial oscillation confined largely to the mixed layer the amplitude of the current was strongly asymmetric about the track with the largest amplitude 1 m s 1 about 80 km to the right of the track there was also an asymmetry of the mixed layer depth and temperature with deeper and cooler values to the right of the track the gradient richardson number was found to have low values in some places less than 1 4 in a layer from 10 to 30 m thick below the base of the surface mixed layer this suggests that shear flow instability played an important role in the vertical mixing that occurred within the mixed layer and upper thermocline

estimate of ocean mixed layer deepening after a typhoon passage over the south china sea by using satellite data abstractthe ocean responses to typhoon cimaron which influenced the south china sea scs from 1 to 8 november 2006 are analyzed based on satellite observed sea surface temperature sst and climatological temperature profiles in the scs mixed layer deepening an important parameter characterizing turbulent mixing and upwelling driven by strong typhoon winds is derived corresponding to the sst drop of 4 4 c on 3 november 2006 the mixed layer deepened by 104 5 m relative to the undisturbed depth of 43 2 m which is consistent with a simulation result from a mixed layer model furthermore baroclinic geostrophic velocity and vorticity are calculated from the surface temperature gradient caused by the typhoon the negative vorticity associated with the typhoon cooling indicated an anticyclonic baroclinic circulation strongest at the base of the mixed layer and at the depth of 50 m the geostrophic speed reached as high as 0 2 m s 1 typhoon cimaron proceeded slowly 1 7 m s 1 when it was making a s

non destructive testing for the assessment of granite decay in heritage structures compared to quarry stone several types of granite found in two architectural heritage monuments were assessed with two non destructive portable techniques schmidt hammer rebound and ultrasound velocity vp similar assessments were conducted on the rock from which the granite was originally quarried for comparison the results obtained which revealed the existence of a direct correlation constitute a useful indication of decay particularly if the approximate dates of construction are known and conversely if they are not such stone assessments may provide a rough estimate of when the structure was built both of these convenient portable and non destructive techniques may be used as reliable indicators of the degree of stone decay

influence of the size of supertyphoon megi 2010 on sst cooling abstractsupertyphoon megi 2010 left behind two very contrasting sst cold wake cooling patterns between the philippine sea 1 5 c and the south china sea 7 c based on various radii of radial winds we found that the size of megi doubles over the south china sea when it curving northwards on average the radius of maximum wind rmw increased from 18 8 km over the philippine sea to 43 1 km over the south china sea the radius of 64 kt typhoon force wind r64 increased from 52 6 km to 119 7 km the radius of 50 kt damaging force wind r50 increased from 91 8 km to 210 km and the radius of 34 kt gale force wind r34 increased from 162 3 km to 358 5 km to investigate the typhoon size effect we conduct a series of numerical experiments on megi induced sst cooling by keeping other factors unchanged i e typhoon translation speed and ocean subsurface thermal structure the results show that if it were not for megi s size increase over the south china sea the during megi sst cooling magnitude woul

field evidence for the influence of weathering on rock erodibility and channel form in bedrock rivers erosion processes in bedrock floored rivers shape channel cross sectional geometry and the broader landscape however the influence of weathering on channel slope and geometry is not well understood weathering can produce variation in rock erodibility within channel cross sections recent numerical modeling results suggest that weathering may preferentially weaken rock on channel banks relative to the thalweg strongly influencing channel form here we present the first quantitative field study of differential weathering across channel cross sections we hypothesize that average cross section erosion rate controls the magnitude of this contrast in weathering between the banks and the thalweg erosion rate in turn is moderated by the extent to which weathering processes increase bedrock erodibility we test these hypotheses on tributaries to the potomac river virginia with inferred erosion rates from 0 1 m kyr to 0 8 m kyr with higher rates in knickpoints spawned by the migratory great falls knickzone we selected nine channel cross sections on three tributaries spanning the full range of erosion rates and at multiple flow heights we measured 1 rock compressive strength using a schmidt hammer 2 rock surface roughness using a contour gage combined with automated photograph analysis and 3 crack density crack length area at three cross sections on one channel all cross sections showed significant p 0 01 for strength p 0 05 for roughness increases in weathering by at least one metric with height above the thalweg these results assuming that the weathered state of rock is a proxy for erodibility indicate that rock erodibility varies inversely with bedrock inundation frequency differences in weathering between the thalweg and the channel margins tend to decrease as inferred erosion rates increase leading to variations in channel form related to the interplay of weathering and erosion rate this observation is consistent with numerical modeling that predicts a strong influence of weathering related erodibility on channel morphology copyright 2017 john wiley sons ltd

a simulation study of the landfall of tropical cyclones abstract by use of a triply nested movable mesh model several ideal simulations of tropical cyclone landfall were performed for a strong zonal flow of 10 m s 1 the integration domain was a 37 45 channel with the innermost mesh having a 22 22 point resolution of 1 6 general characteristics similar to observed landfalling tropical cyclones are obtained in the primary simulation experiment including an abrupt change in the low level 68 m winds at the coastline and a decay of the tropical cyclone at it moves inland additional interesting features subject to model and experimental limitations include little noticeable track change of the model storm when compared to a control experiment with an ocean surface only a possible temporary displacement or the center of the surface wind circulation from the surface pressure center at landfall and a distinct decrease in kinetic energy generation and precipitation a few hours after landfall the sensitivity to the specified land surface conditions was

application of schmidt hammer relative age dating to late pleistocene moraines and rock glaciers in the western tatra mountains slovakia abstract in order to evaluate the potential of the schmidt hammer for relative age dating of late pleistocene moraines and rock glaciers rebound r values were collected at 38 sites in two formerly glaciated valleys in the western tatras in northern slovakia a large statistical population of measurements obtained from moraine and rock glacier surfaces was used to analyze the variability of mean r values in the same lithology and overall southern valley exposition four separate sets of glacial periglacial morphosystems are present at different positions in the western tatras starting from valley outlets to the highest cirques which represent successive phases of deglaciation r value means and 95 confidence intervals for selected last glacial maximum lgm and late glacial lg 1 lg 2 and lg 3 stages respectively 40 1 1 1 46 0 5 53 5 1 0 and 60 5 0 3 are significantly statistically different and values for each age category are comparable for the two analyzed valleys the results of weathering indexes used in conjunction with geomorphological relationships were taken together to reconstruct the pattern of deglaciation on southern tatra slopes it is stated that the schmidt hammer technique may be successfully used as a relative age dating tool for late pleistocene glacial and periglacial deposits and with this method it is possible to differentiate between late glacial moraines and rock glacier systems of different age

techniques for measuring rock weathering application to a dated fan segment sequence in southern tunisia there are a number of techniques for estimating the amount of weathering a clast has undergone these usually have the objective of establishing an ordinal chronology of geomorphological surfaces or investigation of site specific conditions affecting weathering rates three such techniques are applied to a dated sequence of alluvial fan segments in southern tunisia two of these techniques depend on measuring surface roughness the micro roughness meter and a displacement approach and one uses the structural weakening of the rock fabric schmidt hammer the micro roughness meter enables calculation of standard deviation of surface height variation root mean square roughness and surface autocorrelation function of these techniques schmidt hammer rebound values standard deviation root mean square roughness and the displacement technique show systematic changes on the three fan segments which are statistically significant at the 0 05 level however the amount of variance in all datasets is very large indicating the need for caution in application of these techniques for relative dating 1998 john wiley sons ltd

satellite observations of sea surface cooling by hurricanes sea surface cooling associated with 13 hurricanes in the western north atlantic between september 1981 and december 1984 is examined using satellite derived sea surface temperature fields some surface cooling is observed in all cases however because of cloud cover and the fairly weak signal in some cases we see pronounced cooling along an extensive and continuous portion of the storm path for only three strong hurricanes the persistence of cooling following the passage of a hurricane varies from a few days to at least 16 days the amplitude of cooling is moderately well correlated with hurricane strength and is as large as 3 5 c when the hurricanes move rapidly the maximum cooling occurs well to the right of the track approximately 70 km whereas for slowly moving hurricanes the maximum cooling occurs near or on the track because western north atlantic hurricanes are often found in close proximity to high pressure systems daytime satellite images must be made with some care because of diurnal warming

long term morphotectonic evolution in sweden abstract a morphotectonic interpretation of the relief of sweden is presented based on an analysis of the gross forms of the topography computer made topographic profiles covering 76 375 km have been examined together with contour maps new maps of relief and layers of height have also been used three main aspects considered are the relation between the surface of the precambrian basement and its cover rocks the erosional new surfaces developed in both caledonian basement and reexposed precambrian basement and the evolution of the valley pattern the analysis produced the following results the surface of the precambrian basement is a mosaic of old exhumed surfaces and new surfaces formed after erosion of the cover rocks the exhumed surfaces include 1 a sub jotnian surface mainly below cover rocks in downfaulted positions 2 the sub cambrian peneplain and 3 sub mesozoic etch surfaces block faulting was identified in relation to the different exhumed surfaces after the formation of the caledonides a post caledonian surface was cut across the caledonian basement and the precambrian basement with its cover the subsequent evolution of the swedish part of this surface has been traced through several new surfaces in stepped sequences and in relation to the exhumed surfaces five main denudation intervals are distinguished that result in characteristic relief they are preceded by intervals of orogeny uplift and faulting and followed by subsidence and or deposition of sedimentary strata the valley patterns the distribution of new and exhumed surfaces as well as remmants of cover rocks give some fundamental clues to where and when uplift and subsidence occurred historical geomorphology has mainly been based on theories of erosion cycles the relief of the cratons are difficult to fit exclusively into such a system the importance of long lasting covers and of exhumed surfaces have not been considered enough neither the movements of uplift and subsidence reconstruction of geomorphic events appears to be more important for understanding relief evolution than any model as every phase is unique the methods used in this study are worth testing within other cratons

the schmidt hammer as a holocene calibrated age dating technique testing the form of the r value age relationship and defining the predicted age errors most recent developments of schmidt hammer exposure age dating shd as a calibrated age dating tool have been limited by the use of locations at two age control points this has necessitated 1 making assumptions about a linear r value age relationship and 2 basing predictions of age errors only on r value variance at the two age control points this paper analyses 9900 r values obtained from multiple age control points on a sequence of glacio isostatically raised shorelines with well constrained ages skuleskogen high coast world heritage site and environs gulf of bothnia northern sweden ranging from modern to 10 5 ka in age the sampling design involved 30 measurements on granite beach boulders from 30 sites at 11 age control points the r value age relationship is best described by a linear function ordinary least squares ols with an r 2 of 0 89 p 0 0001 predicted age errors are calculated using two approaches 1 ols regression which takes account of the uncertainties associated with the regression line and the age control points and 2 weighted total least squares wtls regression which in addition takes account of possible shoreline age errors and the heteroscedasticity of r value residuals with increasing age with both approaches 95 predicted age errors are relatively modest 355 455 years and 300 515 years respectively with larger r value variance and hence uncertainty for older surfaces and the possibility of further improvement from a more selective field sampling scheme that differentiates between age related and non age related rock surface variability our results also indicate that for certain lithologies and weathering environments it is possible to construct reliable calibrated age curves from relatively few age control points

some aspects of vortex structure related to tropical cyclone motion abstract some effect of tropical cyclone structure on the vortex motion are examined in a nondivergent barotropic numerical model with no basic current as suggested earlier by demaria the initial maximum wind speed has little effect on the track vortex translation associated with the beta effect depends sensitively on the strength of the flow between 300 and 1000 km from the center if the flow in this annulus is made more cyclonic the track will turn cyclonically and move more toward the west in the northern hemisphere the dynamics of this beta drift is studied via a decomposition into symmetric and asymmetric circulations the symmetric flow experiences a slight weakening of the maximum wind speed and an anticyclonic circulation is induced beyond 600 km the asymmetric circulation is dominated by an azimuthal wavenumber one circulation with an anticyclonic gyre east of the center a cyclonic gyre to the west and a nearly uniform broad scale ventilation flow between the gyres the vortex translati

boulder dynamics on an atlantic facing rock coastline northwest ireland abstract the rock coast of northwest ireland comprises steep cliffed headlands and more open coastal sections where bedrock shore platforms are developed many shore platforms are overlain by boulders the locations on the platform from which boulders are derived are marked by holes of fresh and unweathered rock surfaces that are not or are poorly covered by lichen these areas of boulder detachment are termed sockets this paper examines the mapped distributions and physical properties of boulders sockets and shore platform context of an atlantic facing granite shore in county donegal northwest ireland results from schmidt hammer rebound tests show statistically significant differences in rebound values between areas inside and outside of sockets and between sockets and boulders based on their distributions and physical properties relationships between sockets and boulders are explored we calculate that sockets are formed rapidly by winter storms but are also rapidly weathered over c 5 years becoming indistinguishable from the surrounding bedrock platform we argue that in contrast to some studies boulders here were formed during recent winter storms episodically during the last 150 200 years rather than by more ancient waves or by tsunamis however a significant proportion of boulders c 20 are morphometrically dissimilar to sockets we argue that these were formed by infrequent and unusually powerful waves that stripped whole bedrock sheets off the platform surface and which detached boulders from the lower shoreface

a numerical study of the effect of a mountain range on a landfalling tropical cyclone abstract a triply nested movable mesh model was used to study the effects of a mountain range on a landfalling tropical cyclone embedded in an easterly flow of 10 m s 1 the integration domain consisted of a 37 wide and 45 long channel with an innermost mesh resolution of 1 6 an idealized mountain range with maximum height of 958 meters was placed parallel to the shoreline the mountain range which spanned 19 in the north south direction and 5 in the east west direction was centered in the middle of the channel results obtained were compared with a previous landfall simulation performed without the effect of the mountain range included in particular comparison was made of the total storm rainfall maximum wind distribution and storm decay rate it was found that the storm filled much more rapidly in the simulation run with the mountain included the mountain range affected the decay rate through reduction in the supply of latent and kinetic energy into the storm circulation during as well

subsurface initiation of tafoni in granite terrains geophysical evidence from ne spain geomorphological implications abstract granite cavities in the north east of spain which developed below the weathering front are reported these cavities up to 3 m across and probably filled with water saturated weathered granite have been detected by electrical resistivity tomography ert as low resistivity anomalies enclosed in high resistivity media corresponding to unweathered granite rock the caverns appear as hyperbolic reflections in a radargram obtained by ground penetrating radar gpr and show similar shape and size to the tafoni found in the surrounding granite outcrops data gathered in this study support a subterranean origin of some of the tafoni a new conceptual model for the initiation and growth of granite cavities under subsurface conditions is proposed groundwater flow through vertical and sheet fractures triggers preferential weathering at points where meter sized spheroidal pockets of weathered granite develop erosion of the rock mass leads to the exposure of these pockets evolving under subaerial conditions as typical tafoni

lagrangian pathways of upwelling in the southern ocean the spatial and temporal variability of upwelling into the mixed layer in the southern ocean is studied using a 1 10 ocean general circulation model virtual drifters are released in a regularly spaced pattern across the southern ocean at depths of 250 500 and 1000 m during both summer and winter months the drifters are advected along isopycnals for a period of four years unless they outcrop into the mixed layer where lateral advection and a parameterization of vertical mixing is applied the focus of this study is on the discrete exchange between the model mixed layer and the interior localization of interior mixed layer exchange occurs downstream of major topographic features across the indian and pacific basins creating hotspots of outcropping minimal outcropping occurs in the atlantic basin while 59 of drifters outcrop in the pacific sector and in drake passage the region from 140 w to 40 w a disproportionately large amount even when considering the relative basin sizes due to spatial and temporal variations in mixed layer depth the lagrangian trajectories provide a statistical measure of mixed layer residence times for each exchange into the mixed layer the residence time has a rayleigh distribution with a mean of 30 days the cumulative residence time of the drifters is 261 194 days over a period of four years these results suggest that certain oceanic gas concentrations such as co 2 and 14 c will likely not reach equilibrium with the atmosphere before being re subducted

a comparison of the lichenometric and schmidt hammer dating techniques based on data from the proglacial areas of some icelandic glaciers abstract measurements of rhizocarpon section and schmidt hammer r values are reported from the proglacial geomorphic features on the forelands of the icelandic glaciers of kviarjokull holarjokull and heinabergsjokull oraefi and south vatnajokull sandfellsjokull and oldufellsjokull east m rdalsjokull and bruarjokull eyjabakkajokull and west snaefell north vatnajokull these data are used in reconstructions of patterns of glacier recession since the little ice age maximum and the geomorphic signals of climatic versus non climatic events are discussed age control was obtained from various dated substrates by utilizing historical accounts aerial photographs and grave stones three lichen growth rates are calculated a 0 51 mm a 1 corrected to 0 50 mm a 1 with a colonization lag time of

schmidt hammer exposure age dating shd of rock glaciers in the schoderkogel eisenhut area schladminger tauern range austria schmidt hammer rebound values r values enable relative age dating of landforms with r values relating to degree of weathering and therefore length of exposure this method recently termed as schmidt hammer exposure age dating shd was applied to date five rock glaciers size range 0 01 0 12 km2 and one recent rockfall deposit at the study area schoderkogel eisenhut in the schladminger tauern range 14 03 e 47 15 n austria the rock glaciers consist of gneiss or high metamorphic series of mica schist that are comparable in their r values four of them are relict permafrost absent and one is intact containing patches of permafrost on each of the five rock glaciers shd was carried out at 4 6 sites 50 measurements per site along a longitudinal transect from the frontal ridge to the root zone results at all five rock glaciers are generally consistent with each other sharing statistically significant r values along transects the range between the highest and the lowest mean r value at ea

classification of rock weathering at writing on stone provincial park alberta canada a study in applied geomorphology at writing on stone provincial park in southern alberta canada weathering is causing deterioration and loss of archaeologically important indian rock art a procedure devised for the use of park personnel identified four classes of weathering ranging from largely unweathered rock to severely weathered the technique employed simple visual qualitative assessment and photo interpretation of 50 sample sections of sandstone cliff face covering a total area of 354 m2 schmidt hammer tests indicated large variations in rock strength and provided a numerical basis for the visual assessment about 43 per cent of the cliffs are severely to completely weathered 41 per cent show moderate weathering

schmidt hammer exposure age dating shd of late quaternary fluvial terraces in new zealand schmidt hammer sh r values are reported for surface clasts from numerically dated holocene and pleistocene fluvial terraces in the south island of new zealand the r values are combined with previously obtained weathering rind radiocarbon terrestrial cosmogenic nuclide and luminescence terrace ages to derive sh r value chronofunctions for greywacke clasts from four distinct locations our results show that different weathering rates affect the form of the sh r value versus age curve however a fundamental dependency between the two remains constant over timescales ranging from 102 to 105 years power law scaling constants suggest changes in clast weathering rates are primarily affected by climatic precipitation and temperature and sedimentologic variables source terrane petrology age uncertainties of 22 of the surface age suggest that schmidt hammer exposure age dating shd is a reliable calibrated age dating technique for fluvial terraces copyright 2013 john wiley sons ltd