atmospheric vortex streets on a radarsat sar image we analyze the sea surface imprint of two atmospheric vortex streets avs s observed on a radarsat a canadian earth observation satellite synthetic aperture radar sar image of the aleutian islands in the western gulf of alaska acquired on may 5 1999 the radarsat sar instrument is operated in c band with hh polarization these avs s are interpreted as the atmosphere analog of classic von karman vortex streets the sar image along with radiosonde data and surface weather charts reveal that the avs lengths are 196 km and 111 km for avs 1 and avs 2 respectively there are five and two pairs of vortices within each avs the vortex shedding period is estimated to be between 35 and 48 minutes the vortex shedding started approximately 4 6 and 2 6 hours prior to the sar imaging time for avs 1 and avs 2 respectively there are seven and three pairs of vortices within the respective avs s the vortex tangential velocity is estimated to be between 1 7 and 2 3 m s and the energy dissipated during the vortex lifetime is estimated to be between 24 9 and 23 6 j m

the measurement and modelling of rill erosion at angle of repose slopes in mine spoil the process of rill erosion causes significant amounts of sediment to be moved in both undisturbed and disturbed environments and can be a significant issue for agriculture as well as mining lands rills also often develop very quickly from a single rainfall event to a season and can develop into gullies if sufficient runoff is available to continue their development this study examines the ability of a terrestrial laser scanner to quantify rills that have developed on fresh and homogeneous mine spoil on an angle of repose slope it also examines the ability of the siberia erosion model to simulate the rill s spatial and temporal behaviour while there has been considerable work done examining rill erosion on rehabilitated mine sites and agricultural fields little work has been done to examine rill development at angle of repose sites results show that while the overall hillslope morphology was captured by the laser scanner with the morphology of the rills being broadly captured the characteristics of the rills were not well defined the digital elevation model created by the laser scanner failed to capture the rill thalwegs and tops of the banks therefore delineating a series of ill defined longitudinal downslope depressions these results demonstrate that an even greater density of points is needed to capture sufficient rill morphology nevertheless siberia simulations of the hillslope demonstrated that the model was able to capture rill behaviour in both space and time when correct model parameters were used this result provides confidence in the siberia model and its parameterization the results demonstrate the sensitivity of the model to changes in parameters and the importance of the calibration process copyright 2007 john wiley sons ltd

interpentadal variability of temperature and salinity at intermediate depths of the north atlantic ocean 1970 1974 versus 1955 1959 we have composited historical hydrographic observations for the world ocean for two pentads 1955 1959 and 1970 1974 and have objectively analyzed these data for the purpose of studying the temporal variability of temperature and salinity in the north atlantic ocean the subtropical gyre 500 1300 m of the north atlantic was colder and fresher during 1970 1974 compared to 1955 1959 the relatively large changes in temperature and salinity on constant depth surfaces in the subtropical gyre were due to upward displacements of isopycnal surfaces at intermediate depths the eastern portion of the subarctic gyre was also colder and fresher during the 1970 1974 pentad in contrast the western portion of the subarctic gyre exhibited higher temperatures and salinities during 1970 1974 compared to 1955 1959 characteristic differences in temperature and salinity for both gyres were 0 5 c and 0 025 respectively analysis of changes in potential vorticity indicates that in the subtropical gyre potential vorticity increased in all density layers above the 26 5 surface suggesting that convection in this region may have been shallower in 1970 1974 compared to 1955 1959 below the 26 5 surface potential vorticity decreased through the 27 3 surface indicating that deeper than normal convection may have formed the water masses in these layers at 250 m depth relatively large changes in temperature and salinity occurred along the line of maximum climatological mixed layer depth that extends northeast to southwest across the north atlantic ocean

interannual westward propagating baroclinic long wave activity on line p in the eastern midlatitude north pacific abstract for the period 1959 81 quasi zonal hydrographic sections have been made between the southern coast of vancouver island 49 n 126 w and ocean station p 50 n 145 w approximately every two months along this section called line p hydrographic std stations were repeated at nearly the same locations approximately 2 of longitude apart and at closer intervals near the coast as such 13 stations in all were made nearly every two months over the 23 year period thus the line p dataset has particular value in verifying the existence of interannual baroclinic long waves near 50 n in previous studies white kang and magaard and white and saur had found evidence of annual and interannual baroclinic long wave activity in the eastern midlatitude north pacific over the range 20 40 n but earlier attempts could not discover these westward traveling waves along line p in this study both spectral analysis and complex empirical orthogonal function analysis are used to do just that concentrating u

runoff generation and routing on artificial slopes in a mediterranean continental environment the teruel coalfield spain the aim of this study was to identify the mechanisms of runoff generation and routing and their controlling factors at the hillslope scale on artificial slopes derived from surface coal mining reclamation in a mediterranean continental area rainfall and runoff at interrill and microcatchment scales were recorded for a year on two slopes with different substrata topsoil cover and overburden cover runoff coefficient and runoff routing from interrill areas to microcatchment outlets were higher in the overburden substratum than in topsoil and greater in the most developed rill network rainfall volume is the major parameter responsible for runoff response on overburden suggesting that this substratum is very impermeable at least during the main rainfall periods of the year late spring and autumn when the soil surface is sealed in such conditions most rainfall input is converted into runoff regardless of its intensity results from artificial rainfall experiments conducted 3 and 7 years after seeding confirm the low infiltration capacity of overburden when sealed the hydrological response shows great seasonal variability on the overburden slope in accordance with soil surface changes over the year rainfall volume and intensities i30 i60 explain runoff at the interrill scale on the topsoil slope where rainfall experiments demonstrated a typical hortonian infiltration curve however no correlation was found at the microcatchment level probably because of the loss of functionality of the only rill as ecological succession proceeded the runoff generation mechanism on the topsoil slope is more homogeneous throughout the year runoff connectivity defined as the ratio between runoff rates recorded at the rill network scale and those recorded at the interrill area scale in every rainfall event was also greater on the rilled overburden slope and in the most developed rill network the dense rill networks of the overburden slope guarantee very effective runoff drainage regardless of rainfall magnitude rills drain overland flow from interrill sealed areas reducing the opportunity of reinfiltration in areas not affected by siltation runoff generation and routing on topsoil slopes are controlled by grass cover and soil moisture content whereas on overburden slopes rill network density and soil moisture content are the main controlling factors copyright 2002 john wiley sons ltd

an alternate method for estimating dynamic height from xbt profiles using empirical vertical modes abstract a technique is presented that applies modal decomposition to estimate dynamic height 0 450 db from xbt temperature profiles std data are used to establish empirical relationships between vertically integrated temperature profiles and empirical dynamic height modes these are then applied to xbt data to estimate dynamic height a standard error of 0 028 dynamic meters is obtained for the waters of the gulf of alaska an ocean region subject to substantial freshwater buoyancy forcing and with a t s relationship that has considerable scatter the residual error is a substantial improvement relative to the conventional t s correlation technique when applied to this region systematic errors between estimated and true dynamic height were evaluated the 20 year long time series at ocean station p 50 n 145 w indicated weak variations in the error interannually but not seasonally there were no evident systematic alongshore variations in the error in the ocean boundary current regime near the perim

an investigation of the el nino southern oscillation cycle with statistical models 1 predictor field characteristics we have developed two sets of linear models for predicting equatorial pacific sea surface temperatures ssts from the indo pacific trade wind field and the near global sea level pressure slp field the models were constructed using a combination of extended empirical orthogonal functions eeofs and canonical correlation analysis cca a new approach in geophysical modeling our results are of interest both as they show the dominant modes of evolution in the slp and wind fields through the el nino southern oscillation cycle and with respect to the problem of predicting equatorial ssts this paper deals with the first issue above and describes some statistical composites that typify the development of features in the predictor fields over periods of years the results of the eeof analyses clearly show slowly propagating anomalies in both the near global slp and trade wind fields the cca analysis which highlights the co evolution of the two fields suggests a strong coupling between the two and depicts the anomalous features as migrating centers of divergence and convergence that first appear over the eastern indian ocean these features propagate slowly eastward amplify as they expand into the western pacific decline as they cross the central ocean then reamplify over the eastern pacific as reamplification takes place new opposing anomalies appear in the indo pacific descriptions of the predictor data sets and details of the statistical techniques used may also be found in this paper the sst data model validation techniques and forecast model results are presented in a companion paper graham et al this issue

slope aspect affects geomorphic dynamics of coal mining spoil heaps in belgium abstract after the abandonment of coal mining in belgium in the 1960s 1980s many coal tips have been left to themselves increasingly these coal tips are regarded as socio cultural heritage and protected for their environmental value this research analyses the spatial distribution of the main geomorphic processes sheet and rill erosion landsliding rock fragment movement and root throw occurring on coal tips in belgium through mapping of the processes and their causal factors five spoil heaps spread over the major coal basins were studied in detail the spoil heaps were subdivided in homogeneous land units especially with regard to slope gradient vegetation cover and slope aspect qualitative and quantitative observations were done on processes and potential causal factors regressions showed that generally the expression of slope processes on the studied coal tips is 1 strongly dependent on westerly aspect of the slopes 2 independent of slope gradient which presents a narrow range 3 impeded by grass cover and 4 not fully predictable due to variability in type and age of dumped mine spoil

observations and modeling of wind driven currents in the northeast pacific abstract velocity measurements from the interior of the alaskan gyre are presented from a current meter mooring deployed in 4000 m of water at 49 33 n 138 38 w in the vicinity of ocean weather station p the mooring held five current meters which spanned the depth of the water column the data reveal surface intensified motions with flow fluctuations in the upper layers of the water column characterized by long period o 100 d time scales of variability at abyssal depths the flow displays shorter o 20 d time scales of variability the data are compared with observations from one of the nepac moorings in the northeast pacific 42 n 152 w similar characteristics in kinetic energy levels in the vertical structure of the flow and in the vertical variation of eddy time scales are found at this location the current measurements are considered in terms of the linear theory of directly wind driven variability of muller and frankignoul a comparison with simulated currents from a quasigeostrophic num

low frequency temperature fluctuations off bermuda twenty four years of hydrographic stations made by the r v panulirus southeast of bermuda at approximately semi monthly intervals have been used to construct temperature time series at 10 depths ranging from the surface to 2000 m the data contain no significant seasonal signal at depth 250 m subsurface temperature spectra have a broad peak in the eddy containing band at periods 0 100 days and drop rapidly at high frequencies at very low frequencies the spectra indicate some redness down to the largest resolvable time scales most of the energy in the temperature fluctuations is concentrated into two vertical modes which resemble the first two baroclinic normal modes and explain 60 and 23 of the variance respectively the observed spectrum of sea surface temperature sst anomalies has substantially more variance at periods of a year and less than sst anomaly spectra estimated from ship reports on 5 5 grid it is suggested that the excess variance is due to the advection of the sea surface temperature pattern by the underlying field of smaller scale eddies consistently with the observed coherences between surface and deeper temperature records

evolution of an atmospheric karman vortex street from high resolution satellite winds guadalupe island case study vortex streets formed in the stratocumulus capped wake of mountainous islands are the atmospheric analogues of the classic karman vortex street observed in laboratory flows past bluff bodies the q

ventilation of north pacific intermediate waters the role of the alaskan gyre hydrographic data tritium data and potential vorticity calculations suggest that although north pacific intermediate water is formed in the northwest the alaskan gyre might be an additional ventilation site the proposed ventilation is quantified by a vertical column tritium inventory which indicates an excess of 0 08 kg of tritium in the alaskan gyre an evaluation of the energy stored in the water column and of wind and buoyancy forcing shows that during winter conditions enough energy can be pumped into the system to force 26 80 to outcrop in the alaskan gyre model results suggest that relatively limited outcrops in time and space tens of days and several hundred kilometers in diameter can account for the excess tritium

the structure of strongly stratified flow over hills dividing streamline concept in stably stratified flow over a three dimensional hill we can define a dividing streamline that separates those streamlines that pass around the hill from those that pass over the hill the height hs of this dividing streamline can be estimated by sheppard s simple energy argument fluid parcels originating far upstream of a hill at an elevation above hs have sufficient kinetic energy to rise over the top whereas those below hs must pass around the sides this prediction provides the basis for analysing an extensive range of laboratory observations and measurements of stably stratified flow over a variety of shapes and orientations of hills and with different upwind density and velocity profiles for symmetric hills and small upwind shear sheppard s expression provides a good estimate for hs for highly asymmetric flow and or in the presence of strong upwind shear the expression provides a lower limit for hs as the hills become more nearly two dimensional these experiments become less well defined because steady state conditions take progressively longer to be established the results of new studies are presented here of the development of the unsteady flow upwind of two dimensional hills in a finite length towing tank these measurements suggest that a very long tank would be required for steady state conditions to be established upstream of long ridges with or without small gaps and cast doubt upon the validity of previous laboratory studies

variability of the wind stress curl over the north pacific implications for the oceanic response the subinertial frequency wavenumber structure and spatial coherence of wind stress curl and their spatial and temporal variability are described with the emphasis on characteristics which affect the ocean s response to the wind stress curl forcing function wind stress curl over the north pacific between 25 o and 60on was computed for 3 years 1985 1988 from the fleet numerical oceanography center wind product the range from winter peak to summer trough for the mean and variance are typically a factor of 3 4 and 10 respectively with superimposed interannual changes of up to a factor of 2 power spectra vary seasonally and interannually in an essentially frequency independent manner that is consistent with the curl variance however the spectrum over the period band 5 100 days often fails a statistical test for whiteness at the 95 level zonal and meridional wavenumber spectra were estimated for 13 sites distributed around the central eastern north pacific using the maximum likelihood method directional trends with frequency are comparable to those from earlier studies if 3 year long data segments are analyzed with approximate wavenumber symmetry except for the zonal term at mid latitudes for periods shorter than 10 days where eastward propagation is dominant however spectra for shorter data sections sometimes display eastward and westward excursions which are only weakly similar over distances of 1000 km and essentially dissimilar over longer separations the spatial correlation structure of wind stress curl is shown typically to have a main lobe of 1000 km and multiple intercorrelation lobes separated by 2000 km the strength and location of the intercorrelation peaks vary slowly with time these results suggest that curl behavior is more complex than was previously believed that the use of long term averages of or simple parameterizations for the frequency wavenumber spectrum of wind stress curl in model studies may be unrealistic and that more attention to actual curl characteristics at the time oceanic measurements are collected will be required to reconcile models with observations

interdecadal variations in north atlantic sea surface temperature and associated atmospheric conditions abstract evidence is presented for a distinct pattern of ocean atmosphere relationship associated with interdecadal variability in the north atlantic region using a century of surface marine observations it is shown that middle and high latitude sea surface temperature sst display a long term fluctuation with negative anomalies before 1920 and during the 1970s and 1980s positive sst conditions prevailed from about 1930 to 1960 the pattern of interdecadal sst variability is constructed by subtracting the average field during 15 cold years from that during a similar interval of warm years the early century warming and the more recent cooling display a similar spatial pattern in both cases the pattern is basin scale and largely of one polarity with maxima in the vicinity of iceland in the labrador sea and northeast of bermuda the corresponding differences in surface atmospheric conditions are determined by averaging and subtracting in the same manner fields of sea level pressure slp and surf

a local time dependent sverdrup balance in the eastern north pacific ocean direct observations of the dynamic balance between time dependent winds and deep ocean currents are described for the eastern north pacific ocean at 42 n 152 w currents from 150 to 4000 meters below the surface at frequencies from 0 01 to 0 1 cycle per day are significantly correlated with the wind stress curl derived from u s navy operational wind fields the horizontal currents are depth independent below 300 meters and they flow parallel to the potential vorticity gradient derived from the earth9s rotation and the large scale bottom topography these characteristics are expected for such periodic motions with horizontal scales larger than 500 kilometers and represent a generalized sverdrup balance between the atmospheric forcing and the oceanic response

variability in the gulf of alaska from geosat altimetry data satellite altimetry was used to examine annual and interannual variability in the gulf of alaska region crossover data from the geosat geodetic mission gm and collinear data from the exact repeat mission erm were processed separately to form sea surface height anomalies at grid points the time series from the gm and erm were then combined to produce a 3 75 year data set the time series from the erm data set agreed fairly well with hydrographic dynamic heights at several locations with an average correlation of 0 70 between the two data sets the combined and erm altimetric data sets were analyzed using empirical orthogonal functions eofs these revealed variability that occurs primarily on annual and interannual time scales a comparison with eof analysis of the atmospheric pressure field during the same time periods showed that the annual variation in pressure seemed to be reflected in both the combined and erm altimetric data sets the amplitude time series of the first mode in the combined data set was very similar to the north pacific pressure index during the 1985 1989 time frame the maximum correlation was at a lag of 250 days finally an interannual mode was present in all three data sets which was closely linked to the baroclinic variations measured by the hydrographic data

initial hydro geomorphic development and rill network evolution in an artificial catchment the formation of erosion rills and gullies is a critical step in land surface development but possibilities to study initial unaffected surface development under natural conditions and with well defined initial and boundary conditions are rare the objective of this study was to characterize rill network development from point zero in the artificially created catchment huhnerwasser to ensure unaffected development the study was largely restricted to the analysis of remotely sensed data we analyzed a series of photogrammetry based digital elevation models dems for 10 points in time over a period of five years and beginning with the initial state the evolving erosion rill network was quantitatively described based on mapping from aerial photographs dems and rill network maps were combined to specifically analyze the development of morphometry for different parts of the network and to characterize energy dissipation and connectivity the restriction to remote sensing data did not allow for analyzing specific processes governing rill network development nevertheless two major development phases could be characterized we observed a phase of growth of the rill network along with variations in drainage patterns during the first two years of development and a subsequent phase of reduction of its area along with comparably stable patterns region specific analysis of morphometry indicates that besides effects of changing sediment characteristics and vegetation cover development locally evolving hydro geomorphic feedback cycles influenced this development results show an increasing similarity of overall statistical characteristics e g drainage density for two parts of the catchment but a persistent influence of initial conditions on specific rill geometry the observed development towards higher orderliness and increased connectivity is consistent with experiments and concepts on drainage network evolution across scales however we did not observe major influences of rill piracy and cross grading or a reduction of energy dissipation with network development copyright 2013 john wiley sons ltd

soil and water losses from new citrus orchards growing on sloped soils in the western mediterranean basin ten representative research sites were selected in eastern spain to assess soil erosion rates and processes in new citrus orchards on sloping soils the experimental plots were located at representatives sites on limestone in areas with 498 to 715 mm year 1 mean annual rainfall north facing slopes herbicide treated and new less than 3 years old plantations ten rainfall simulation experiments 1 h at 55 mm h 1 on 0 25 m2 plots were carried out at each of the 10 selected study sites to determine the interill soil erosion and runoff rates the 100 rainfall simulation tests 10 10 m showed that ponding and runoff occurred in all the plots and quickly 121 and 195 s respectively following rainfall initiation runoff discharge was one third of the rainfall and sediment concentration reached 10 4 g l 1 the soil erosion rates were 2 4 mg ha 1 h 1 under 5 year return period rainfall thunderstorms these are among the highest soil erosion rates measured in the western mediterranean basin similar to badland mine spoil and road embankment land surfaces the positive relationship between runoff discharge and sediment concentration r2 0 83 shows that the sediment availability is very high soil erosion rates on new citrus orchards growing on sloped soils are neither tolerable nor sustainable copyright 2009 john wiley sons ltd

an observational study of vortex spacing in island wake vortex streets abstract vortex streets are a frequent occurrence in stratocumulus topped flow downwind of mountainous islands theoretical studies dating back to von karman supported by laboratory and numerical studies have yielded similarity theories for the size and spacing of these vortices behind bluff bodies despite dynamical differences between such two dimensional flows and the three dimensional flow past isolated islands satellite case studies suggest these geometric similarities may also hold for the atmospheric case in this study two of the resulting dimensionless ratios are measured using satellite imagery one is the aspect ratio between cross street and along street spacing of the vortices the second is the ratio of the cross street spacing to the crosswind width of the island a 30 image sample from the aqua and terra moderate resolution imaging spectroradiometer satellites is analyzed to obtain these ratios the resulting set of values for the two dimensionless ratios is tested against the values f

human topographic signatures and derived geomorphic processes across landscapes abstract the earth s surface morphology in an abiotic context is a consequence of major forcings such as tectonic uplift erosion sediment transport and climate recently however it has become essential for the geomorphological community to also take into account biota as a geomorphological agent that has a role in shaping the landscape even if at a different scale and magnitude from that of geology although the modern literature is flourishing on the impacts of vegetation on geomorphic processes the study of anthropogenic pressures on geomorphology is still in its early stages topography emerges as a result of natural driving forces but some human activities such as mining agricultural practices and the construction of road networks directly or indirectly move large quantities of soil which leave clear topographic signatures embedded on the earth s morphology these signatures can cause drastic changes to the geomorphological organization of the landscape with direct consequences on earth surface processes this review provides an overview of the recent literature on the role of humans as a geological agent in shaping the morphology of the landscape we explore different contexts that are significantly characterized by anthropogenic topographic signatures landscapes affected by mining activities road networks and agricultural practices we underline the main characteristics of those landscapes and the implications of human impacts on earth surface processes the final section considers future challenges wherein we explore recent novelties and trials in the concept of anthropogenic geomorphology herein we focus on the role of high resolution topographic and remote sensing technologies the reconstruction or identification of artificial or anthropogenic topographies provides a mechanism for quantifying anthropogenic changes to landscape systems this study may allow an improved understanding and targeted mitigation of the processes driving geomorphic changes during anthropogenic development and help guide future research directions for development based watershed studies human society is deeply affecting the environment with consequences on the landscape therefore establishing improved management measures that consider the earth s rapidly changing systems is fundamental

observations of wind forced deep ocean currents in the north pacific this study examines the atmospheric response of the deep ocean using 200 instrument years of moored current measurements from across the breadth of the mid latitude north pacific we have found evidence of a seasonal modulation in the ocean eddy kinetic energy beneath the thermocline at several locations north of 35 n this modulation is often in phase with the local atmospheric forcing function at frequencies between 0 1 and 0 01 cpd correlations between the local wind stress curl and the deep currents have been found for a few locations the local forced response is parallel to the potential vorticity gradient f h and consistent in amplitude with a local topographic sverdrup balance nonlocal forcing in the form of flow along isolines of potential vorticity has been estimated and it is comparable to the observed flow at some locations but the modeled flow is not correlated with the observations throughout the mid latitude north pacific the bottom slope tends to enhance the effect this suggests that topography narrows the available bandwidth for forced barotropic rossby waves facilitating a quasi steady topographic sverdrup response over most of the basin however the enhanced effect reduces the magnitude of the ocean s response to wind forcing nonlocally forced sverdrup currents flow along isolines of f h are the dominant component but are only of the order of 1 cm s 1 locally forced sverdrup currents flow across isolines of f h are typically of the order of 0 1 cm s 1 rms and are not commonly measured hence these wind forced variations are a background level signal in the mid latitude eddy kinetic energy in a few isolated areas the bottom slope reduces the effect in these regions the local sverdrup response is amplified and has been observed

interdecadal variations in the alaska gyre abstract climatic dynamic topography variations in the alaska gyre during the period 1968 1990 are described with an objective analysis of more than 12000 std and xbt stations and coads wind stress data interannual dynamic height and sst variations were correlated and were consistent with recently described large scale climatic shifts in the north pacific the gyre was cantered more to the east circulation appeared stronger and sst was lower during the early to mid 1970s than during the 1980s the aleutian low np and pna indices intensified during the interim but the response did not appear as a gyre spinup instead the associated wind stress anomalies forced a slowly varying dynamic height anomaly across the eastern and northern part of the gyre through ekman convergence which had the effect of displacing the gyre s low somewhat to the wsw in the 1980s the wind curl spectrum was white and the slow oceanic response was modelled as stochastic forced climate variability with a simple first order m

the anticyclonic baroclinic eddy off sitka alaska in the northeast pacific ocean abstract among the many mesoscale eddies found in the northeast pacific ocean is a well developed anticyclonic baroclinic eddy situated within a few hundred kilometers of sitka alaska 57 n 138 w it has definitely been observed during spring and summer 1958 summer 1960 and summer 1961 observations made at other times show some evidence of its occurrence also the trajectories of three norpax drifting buoys for april may 1977 also indicated the probable presence of an eddy there the eddy whose diameter ranges from 200 to 300 km and whose depth extends to 100 m and probably to as much as 2000 m recurs at the same location the center of the eddy is characterized by the following features the surface water is less saline and only somewhat warmer than at its periphery at depths within and below the halocline it is warmer less saline and contains more dissolved oxygen than at the periphery and a warm core is situated within the halocline the halocline is usually depressed by less than 100 m but

interdecadal variability of the pacific ocean model response to observed heat flux and wind stress anomalies variability of the pacific ocean is examined in numerical simulations with an ocean general circulation model forced by observed anomalies of surface heat flux wind stress and turbulent kinetic energy tke over the period 1970 88 the model captures the 1976 77 winter time climate shift in sea surface temperature as well as its monthly seasonal and longer term variability as evidenced in regional time series and empirical orthogonal function analyses examination of the surface mixed layer heat budget reveals that the 1976 77 shift was caused by a unique concurrance of sustained heat flux input anomalies and very strong horizontal advection anomalies during a multi month period preceding the shift in both the central pacific region where cooling occurred and the california coastal region where warming occurred in the central pacific the warm conditions preceding and the cold conditions following the shift tend to be maintained by anomalous vertical mixing due to increases in the atmospheric momentum flux tke input into the mixed layer which deepens in the model after the shift from the early 1970s to the late 1970s and 1980s since the ocean model does not contain feedback to the atmosphere and it succeeds in capturing the major features of the 1976 77 shift it appears that the midlatitude part of the shift was driven by the atmosphere although effects of midlatitude ocean atmosphere feedback are still possible the surface mixed layer heat budget also reveals that in the central pacific the effects of heat flux input and vertical mixing anomalies are comparable in amplitude while horizontal advection anomalies are roughly half that size in the california coastal region in contrast where wind variability is much weaker than in the central pacific horizontal advection and vertical mixing effects on the mixed layer heat budget are only one quarter the size of typical heat flux input anomalies

the barotropic response of the subpolar north pacific to stochastic wind forcing in a recent observational study koblinsky et al 1989 attempted to demonstrate that the topographic sverdrup balance can account for mesoscale current fluctuations with periods between 10 and 100 days in the abyssal north pacific however the topographic sverdrup balance proved difficult to verify systematically over the north pacific in this paper the conditions required to obtain the topographic sverdrup balance are investigated through numerical experiments with a stochastically forced barotropic quasi geostrophic numerical model of the subpolar north pacific in the numerical experiments the topographic sverdrup balance emerges from area averages of the terms in the vorticity equation but only for periods longer than about 40 days when the averages are taken over 4 4 region this period increases when averages are taken over progressively smaller regions an examination of vorticity balances at individual points along sections through the model domain indicates that the topographic sverdrup balance is not obtained at individual points even for very long period motions the possibility of verifying topographic sverdrup dynamics with oceanic data is considered it is argued that topographically generated small scales in the velocity field reduce the likelihood that the topographic sverdrup balance can be systematically observed in velocity measurements from individual current meter moorings the results suggest that the vorticity balance is complex and that topographic sverdrup dynamics cannot be expected to provide an adequate explanation for the seasonal modulation of the abyssal eddy kinetic energy that is observed with moored instrumentation in the north pacific

rain infiltration into loess soils from different geographic regions abstract loess soils are among the most erodible soils therefore evaluating and enhancing infiltration is paramount in controlling soil loss a laboratory study was conducted to evaluate the relative difference in infiltration among selected loess surface and subsurface soils from belgium canada china and the united states representing the major loess belts of the northern hemisphere soils were subjected to simulated rainstorms of constant intensity i 41 1mm h 1 duration 2 hours and energy rate 27 0 j m 2 per mm of rain infiltration runoff and soil water pressure were continuously monitored infiltration was described by a linear relationship for the pre ponding period and by a power series for the post ponding period differences in infiltration response were attributed to differences in soil properties such as differences in organic matter particle size swelling clay content fe oxyhydroxides and carbonates despite the high organic carbon content and coarser texture of the canadian loess surface soil the presence of highly expansive smectitic clay caused a rapid reduction in infiltration rates indicating the importance of soil mineralogical constituents in surface seal development

quasi geostrophic ocean response to real wind forcing the effects of temporal smoothing abstract a one degree flat bottom eight layer quasi geostrophic model of the north pacific ocean is forced by six different wind stress curl datasets all derived from seven years of twice daily analyses at the european centre for medium range weather forecasts 1980 86 the six datasets with nominal averaging times of 1 2 3 7 14 and 30 days are obtained by carefully filtering in the frequency domain this filtering greatly reduces the variance typically by 90 for 30 day averaging because the wind stress curl spectrum is nearly white in frequency it also smoothes spatially reducing high wavenumber variance to a greater degree than variance near wavenumber zero the climatology of the ecmwf wind stress curl does not show any unexpected differences from climatologies based on historical marine wind observations the wind stress curl is neither temporally nor spatially stationary with the high frequency variance being much larger during the winter season and over the northern half of the north

restoring earth surface processes through landform design a 13 year monitoring of a geomorphic reclamation model for quarries on slopes the application of geomorphic principles to land reclamation after surface mining has been reported in the literature since the mid 1990s mostly from australia canada and the usa this paper discusses the reclamation problems of contour mining and quarries on slopes where steep gradients are prone to both mass movement and water erosion to address these problems simultaneously a geomorphic model for reclaiming surface mined slopes is described called the highwall trench concave slope model it was first applied in the 1995 reclamation of a quarry on a slope la revilla in central spain the geomorphic model does not reproduce the original topography but has two very different sectors and objectives i the highwall trench sector allows the former quarry face to evolve naturally by erosion accommodating fallen debris by means of a trench constructed at the toe of the highwall ii the concave slope base sector mimicking the landforms of the surrounding undisturbed landscape promotes soil formation and the establishment of self sustaining functional ecosystems in the area protected from sedimentation by the trench the model improves upon simple topographic reconstruction because it rebuilds the surficial geology architecture and facilitates re establishment of equilibrium slopes through the management and control of geomorphic processes thirteen years of monitoring of the geomorphic and edaphic evolution of la revilla reclaimed quarry confirms that the area is functioning as intended the highwall is backwasting and material is accumulating at the trench permitting the recovery of soils and vegetation on the concave slope however the trench is filling faster than planned which may lead to run off and sedimentation on the concave slope once the trench is full the lesson learned for other scenarios is that the model works well in a two dimensional scheme but requires a three dimensional drainage management breaking the reclaimed area into several watersheds with stream channels copyright 2010 john wiley sons ltd