eddy zonal flow feedback in the southern hemisphere abstract the variability of the zonal mean zonal wind in the southern hemisphere is studied using eof analysis and momentum budget diagnostics of ncep reanalysis data 1978 97 the leading eof of the zonal mean zonal wind is well separated from the remaining eofs and represents the north south movement of the midlatitude jet analysis of the momentum budget shows that a positive feedback between the zonal mean wind anomalies and the eddy momentum fluxes accounts for the unusual persistence of eof1 and plays an important role in the selection of the leading eof of midlatitude variability further analysis also shows a propagating feedback common to both eof1 and eof2 which is responsible for the poleward drift of wind anomalies with time the observations support the following feedback mechanism anomalous baroclinic wave activity is generated at the latitude of anomalous temperature gradient that by thermal wind coincides with the latitude of the anomalous zonal jet the net propagation of baroclinic

environmental controls rates and mass transfers of contemporary hillslope processes in the headwaters of two glacier connected drainage basins in western norway the role of hillslopes functioning as the key elements for sediment production storage and transfers is particularly important within headwater systems in cold climate mountain landscapes that are considered to react sensitively to climate change and human impact environmental controls rates and sedimentary mass transfers of the contemporary slope processes were explored within the headwater systems of the parabolic shaped and glacier connected erdalen and bodalen drainage basins in western norway the identified relevant contemporary processes in both drainage basins include rockfalls and boulder falls snow avalanches slush flows debris flows slow mass movements and creep processes wash and chemical denudation and fluvial transport of solutes suspended sediments and bedload these denudational processes were analyzed based on an extensive geomorphic monitoring program conducted over a period of four years 2009 2012 combined with detailed geomorphological mapping and in depth studies of the most important slope processes a range of different monitoring and field techniques was applied the results show that the intensity of contemporary denudational processes in erdalen and bodalen is rather low and appears to be in a range of magnitude comparable to a number of other cold climate environments situated in the higher latitudes of the northern hemisphere the present day spatio temporal pattern of the denudational slope processes occurring in the headwater systems is controlled by a complex combination of meteorological and morphometric factors a comparison of the different denudational slope processes according to their annual mass transfers reveals the highest relative importance for rockfalls snow avalanches slope wash and chemical slope denudation in erdalen as well as for rockfalls chemical slope denudation snow avalanches and debris flows in bodalen the revealed differences between the single headwaters regarding the absolute and relative importance of the denudational slope processes are seen as a consequence of the different glacially inherited valley morphometries however due to the generally low process intensities the postglacial modification of the inherited glacial relief is altogether minor in both valleys

extratropical transition of southwest pacific tropical cyclones part ii midlatitude circulation characteristics abstract this second of two papers on extratropical transition et over the southwest pacific ocean focuses on the variability of et a climatology of et onset based on a previously described objective technique shows that et commences 15 of latitude nearer the equator on average than similar cases from the northern hemisphere characteristic midlatitude circulation patterns accompanying et near 30 s are identified by means of empirical orthogonal function eof analysis of 50 storms the first eigenvector pattern explaining nearly half the circulation variability expresses relaxed and enhanced pressure gradients south of the storm that define composites similar to cradled and captured classifications previously described for the southeast indian ocean the second eof distinguishes redeveloping from weakening storms reintensifying storms were located beneath strong cyclonic vorticity advection cva near the equatorward entrance region of an upper jet whereas the upper jet was well to the west of

weathering rinds and rock coatings from an arctic alpine environment northern scandinavia coarse rock debris exposed in the subaerial environment of northern sweden displays the development of a wide variety of surface coatings these include weathering rinds as well as a great diversity of geochemical coatings including those dominated by ca fe si and al each of these types of rock coatings displays a high degree of geochemical complexity the weathering rinds exhibit both geochemical and morphologic changes to the parent rock cores including extensive dissolution oxidation and hydration as well as disaggregation fracturing and cementation by secondary geochemical coatings chemical breakdown of the rock to form weathering rinds includes loss of k si mg and ca and buildup of fe weathering rinds are fundamentally the result of dissolution as no clay minerals were identified in the rinds rock coatings are distinguished from rinds by their clear accretionary nature despite the distinction made between weathering rinds and rock coatings it is important to note that often the two are intimately related the presence of rock coatings as well as weathering rinds on rock surfaces amplifies the important role played by geochemical processes in the arctic alpine climate of northern sweden in particular as well as its significance in landscape evolution in such environments in general

analysis and modeling of the arctic oscillation using a simple barotropic model with baroclinic eddy forcing abstract in this study a numerical simulation of the arctic oscillation ao is conducted using a simple barotropic model that considers the barotropic baroclinic interactions as the external forcing the model is referred to as a barotropic s model since the external forcing is obtained statistically from the long term historical data solving an inverse problem the barotropic s model has been integrated for 51 years under a perpetual january condition and the dominant empirical orthogonal function eof modes in the model have been analyzed the results are compared with the eof analysis of the barotropic component of the real atmosphere based on the daily ncep ncar reanalysis for 50 yr from 1950 to 1999 according to the result the first eof of the model atmosphere appears to be the ao similar to the observation the annular structure of the ao and the two centers of action at pacific and atlantic are simulated nicely by the barotropic s model therefore the atmospheric low frequency variabilities

multiple regimes and low frequency oscillations in the southern hemisphere s zonal mean flow abstract this paper studies multiple regimes and low frequency oscillations in the northern hemisphere zonal mean zonal flow in winter using 55 yr of daily observational data the probability density function estimated in the phase space spanned by the two leading empirical orthogonal functions exhibits two distinct statistically significant maxima the two regimes associated with these maxima describe persistent zonal flow states that are characterized by meridional displacements of the midlatitude jet poleward and equatorward of its time mean position the geopotential height anomalies of either regime have a pronounced zonally symmetric component but largest amplitude anomalies are located over the atlantic and pacific oceans high frequency synoptic transients participate in the maintenance of and transitions between these regimes significant oscillatory components with periods of 147 and 72 days are identified by spectral analysis of the zonal flow time series these oscillations are described b

a 10 year record of the weathering rates of surficial pebbles in karkevagge swedish lapland abstract between 1999 and 2004 nylon mesh bags containing 6 2 mm diameter fragments of crushed dolomite or granite were exposed to weathering on the surfaces of birch dryas heath heath meadow solifluction meadow and willow vegetation communities in karkevagge a glaciated trough in swedish lapland the material in the bags had previously been in the same locations from either 1994 or 1995 when it had been placed in the field as freshly crushed pebbles results of the mass losses resulting from chemical weathering during the first 4 or 5 year period were reported in dixon et al dixon j c thorn c e darmody r g schlyter p 2001 weathering rates of fine pebbles at the soil surface in karkevagge swedish lapland catena 45 273 286 in catena the spatial results of the second 5 year period confirm those determined during the first period in general wetter more acidic sites promoted greater losses from the dolomite but the losses from the granite were too small to reveal distinctive spatial patterns dolomite consistently weathered faster than granite in at a site comparisons with total mass losses between 1999 and 2004 ranging from 1 90 to 9 98 for dolomite and 0 07 to 4 02 for granite spatial distinctions were blurred during the second period due to significant losses of bags at dry sites from atmospheric exposure however at a site comparisons between the two study periods revealed statistically significantly greater losses during the second period when compared to the first in the absence of appropriate ground climate data it is worth noting that air climates were both warmer and wetter during both study periods when compared to the 1961 1990 averages and the second 5 year study period was also warmer and wetter than the first

field based experimental determination of the weathering rates of the cappadocian tuffs abstract since the last eruption in the cappadocia region that resulted in the formation of irregular hard thick lava layers on top of the cappadocian tuffs atmospheric processes have preferentially sculptured the tuffs the erosion processes have resulted in some beautiful topographical landscape features the so called fairy chimneys however erosion which is an important factor in the formation of fairy chimneys in the early stages has a negative effect on their future over time the number of visitors to this region has also increased and therefore in addition to natural erosion the effects of localized erosion resulting from tourism at the site have increased in the last few decades the physical mineralogical and mechanical properties of the cappadocian tuffs have been widely investigated in previous studies but their weathering characteristics particularly weathering rate were not determined in these studies determination of the weathering rate of these rocks is mandatory especially for conservation projects which should be urgently applied in order to protect this heritage in this study a comprehensive research program was carried out on the weathering properties of the cappadocian tuffs and the weathering rate was determined in field and laboratory investigations to this purpose a detailed field investigation was performed besides field observations the mineralogical physical and mechanical properties of tuffs were also determined in addition to durability evaluation by the slake durability index test wetting drying and freezing thawing tests were also performed for weathering rate assessment of the cappadocian tuffs in order to account for overburden load on some specific parts of pillars these wetting drying and freezing thawing tests were performed under loads the results obtained from field observations of old man made structures and from laboratory studies show that the weathering rate varies between 0 03 and 0 59 mm year for the esbelli tuff and 0 4 and 2 5 mm year for softer part of the kavak member

field and laboratory experiments on weathering rates of granodiorite separation of chemical and physical processes to study the rate and mechanism of granitic rock weathering field weathering experiments using granodiorite tablets diameter 3 5 cm height 1 1 cm weight 30 g were conducted at a catchment over 10 yr the tablets were exposed at three positions having different weathering conditions ground surface above aquifer and in aquifer the weight of the tablets decreased linearly with time 0 022 wt yr 1 for the ground surface 0 013 wt yr 1 above the aquifer and 0 42 wt yr 1 in the aquifer only minor changes of the tablet surface were observed after 10 yr of weathering at the ground surface and above the aquifer in contrast the tablets in the aquifer were remarkably weathered and weathering of biotite was particularly noticeable whereas that of plagioclase k feldspar quartz and hornblende was minor or moderate the weathering of granodiorite is inferred to proceed by initial dissolution of mineral grain boundary chemical process and subsequent detachment of the mineral grain physical process to evaluate the amount of weathering caused only by the chemical process a laboratory dissolution experiment was conducted on the granodiorite tablet using a flow through reactor at 20 c and ph 6 7 the obtained rates 0 0078 0 010 wt yr 1 were 50 times slower than the field rate in the aquifer this result shows that the contribution of the physical process to granodiorite weathering in the aquifer is very large compared to that of the chemical process and the relative intensities of the two processes during the 10 yr weathering are estimated to be chemical physical 1 50

an observational study of the intraseasonal poleward propagation of zonal mean flow anomalies abstract the poleward propagation of zonal mean relative angular momentum mr anomalies is examined using ncep ncar reanalysis data for both the winter and summer seasons of the northern and southern hemisphere this analysis is performed with a regression analysis using base latitudes in the subtropics midlatitudes and high latitudes it is found that the poleward mr anomaly propagation occurs at all latitudes with the propagation speed being greater in the subtropics and high latitudes compared to midlatitudes other fields such as eddy angular momentum flux convergence eddy heat flux friction torque and 300 mb streamfunction are regressed for the northern hemisphere winter and the southern hemisphere summer the main finding is that in the subtropics and midlatitudes the poleward mr anomaly propagation is primarily due to high frequency 10 day transient eddy angular momentum flux convergence and in high latitudes the propagation is mostly due to the summation of cross frequency and low fr

distribution and effectiveness of nivation in mediterranean mountains penalara spain abstract snow accumulation is responsible for geomorphic and biogeographic processes taking place in the southern sector of the penalara massif in central spain 40 51 n 3 57 w max altitude 2428 m at pico de penalara this work compares the intensity of nivation on the eastern slope leeward of the prevailing westerly winds and heavily eroded by glacial activity during the pleistocene to that of the western slope on the windward side unaffected by glacial erosion and completely covered by a thick weathering mantle on the eastern slope nivation is effective only where the weathering mantle is exposed or on morainic formations it does not occur on the landforms derived from glacial erosion in contrast the western side shows almost no evidence of snow action except where catastrophic mass movements have altered the regularity of the slope during the post glacial epoch nivation cirques formed in the scars left by mass wasting in the last 30 years spring temperatures have increased and this activity has diminished the pattern of evolution observed at penalara can be extrapolated to other mediterranean mountains with similar characteristics such as marginal glacial activity during the pleistocene unconsolidated formations on the summits caused by chemical weathering and dry hot summers that can increase the effectiveness of nivation

weathering rates of fine pebbles at the soil surface in karkevagge swedish lapland abstract in 1994 nylon mesh bags containing 6 2 mm diameter fragments of either freshly crushed dolomite or granite were placed on meadow solifluction meadow birch heath and alpine tundra vegetation that cover surfaces within karkevagge a glaciated arctic alpine valley in swedish lapland each vegetation category contained three replicate sites comprising one bag of each rock type in 1995 the study was extended to dryas heath and willow two sites only surfaces percentage annual weight loss was used as a metric of chemical weathering rates one site in each of the 1994 categories was measured in 1995 all sites were measured in 1999 two dolomite and granite standards stored in the laboratory and subjected to identical cleaning and weighing regimes to the field samples exhibited no more than a 0 24 total weight loss after 5 years the percentage weight loss in the subgroup examined after 1 year dolomite 0 54 year granite 0 41 year significantly exceeded the average annual loss for the subsequent 4 years in all cases dolomite 0 40 year granite 0 07 year ten sites with a 5 year record had a mean annual loss of 0 326 0 115 year two standard errors for dolomite and 0 121 0 020 year for granite assuming an exponential decay model a 0 326 year rate of loss produces a half life of approximately 212 years and a 0 121 year loss rate a half life of approximately 570 years kruskal wallis one way anova on rank ordered data determined significant differences in dolomite pebble mass loss between the dryas heath and willow plus meadow microenvironments as well as between the birch forest and the willow plus meadow microenvironments the underpinning factor behind these differences appears to be moisture differences a similar test failed to determine statistically significant differences for the granite pebbles dolomite appears to be a viable medium for determining mass loss rates over quite modest time periods providing that the number of samples is sufficiently large

a geomatics based approach for the derivation of the spatial distribution of sediment transport processes in periglacial mountain environments within this paper modern techniques such as satellite image analysis and tools provided by geographic information systems gis are exploited in order to extend and improve existing techniques for mapping the spatial distribution of sediment transport processes the processes of interest comprise mass movements such as solifluction slope wash dirty avalanches and rock and boulder falls they differ considerably in nature and therefore different approaches for the derivation of their spatial extent are required a major challenge is addressing the differences between the comparably coarse resolution of the available satellite data landsat tm etm 30 in x 30 m and the actual scale of sediment transport in this environment a three stepped approach has been developed which is based on the concept of geomorphic process units gpus parameterization process area delineation and combination parameters include land cover from satellite data and digital elevation model derivatives process areas are identified using a hierarchical classification scheme utilizing thresholds and definition of topology the approach has been developed for the karkevagge in sweden and could be successfully transferred to the rabotsbekken catchment at okstindan norway using similar input data copyright c 2008 john wiley sons ltd

anatomy of synoptic eddy nao interaction through eddy structure decomposition abstracta method of eddy structure decomposition is proposed to detect how low frequency flow associated with the north atlantic oscillation nao organizes systematically synoptic eddy se activity to generate in phase and upstream feedbacks in this method a statistical eddy streamfunction ses field defined by the three point covariance of synoptic scale streamfunction is introduced to characterize spatiotemporal se flow structures the ses field is decomposed into basic and anomalous parts to represent the climatological se flow structure and its departure these two parts are used to calculate the basic and anomalous eddy velocity eddy vorticity and thus eddy vorticity flux fields in order to elucidate those two se feedbacks onto the nao this method is validated by the fact that the observed anomalous eddy vorticity flux field can be reproduced well by two linear terms the basic eddy velocity field multiplied by anomalous eddy vorticity field and the anomalous eddy velocity field multiplied

wave maintained annular modes of climate variability abstract the leading modes of month to month variability in the northern and southern hemispheres are examined by comparing a 100 yr run of the geophysical fluid dynamics laboratory gcm with the ncep ncar reanalyses of observations the model simulation is a control experiment in which the ssts are fixed to the climatological annual cycle without any interannual variability the leading modes contain a strong zonally symmetric or annular component that describes an expansion and contraction of the polar vortex as the midlatitude jet shifts equatorward and poleward this fluctuation is strongest during the winter months the structure and amplitude of the simulated modes are very similar to those derived from observations indicating that these modes arise from the internal dynamics of the atmosphere dynamical diagnosis of both observations and model simulation indicates that variations in the zonally symmetric flow associated with the annular modes are forced by eddy fluxes in the free troposphere while

kinematics of eddy mean flow interaction in an idealized atmospheric model abstractthe authors analyze atmospheric variability simulated in a two layer baroclinic channel quasigeostrophic model by combining eulerian and feature tracking analysis approaches the leading mode of the model s low frequency variability lfv is associated with the irregular shifts of the zonal mean jet to the north and south of its climatological position accompanied by simultaneous intensification of the jet while the deviations from the zonal mean fields are dominated by propagating anomalies with wavenumbers 3 5 the model s variability is shown to stem from the life cycles of cyclones and anticyclones in particular synthetic streamfunction fields constructed by launching idealized composite mean eddies along the actual full model simulated cyclone anticyclone tracks reproduce nearly perfectly not only the dominant propagating waves but also the jet shifting lfv the composite eddy tracks conditioned on the phase of the jet shifting variability migrate north or south along with the zonal mea

time dependent physicomechanical behavior of ballasts used for railway between sabuncupinar and kutahya in western turkey geomaterials used in engineering projects and man made structures naturally weather as a result of various physicochemical factors due to their long term exposure to environmental conditions geomaterials used for these purposes provide important information for understanding the effect of weathering processes on their time dependent physical mineralogical and mechanical changes since 1920s ballasts have been extracted from a quarry composed of volcanic rocks and located in sabuncupinar town to construct a railway between kutahya and this town in western turkey in present study a research was carried out on leftover and used ballasts and block samples taken from this site to assess their weathering properties in terms of time dependent durability and stability characteristics the weathering process originated mineralogical and chemical variations of collected samples were identified by microscopic studies scanning electron microscopy sem with energy dispersive x ray spectroscopy system eds and x ray diffraction xrd techniques based on sem eds analyses it resulted evident that the fe content increases in weathering rind of ballasts in comparison with their relatively fresh parts although environmental conditions caused weathering rinds of 2 2 5 mm in the outer part of ballasts within 90 5 years the petrographic and xrd analyses reveal a significant similarity between relatively fresh and weathering rinds of ballast in terms of mineralogical composition however despite that mineralogical similarity the effect of time dependent weathering processes was obviously seen from the results of slake durability and los angeles abrasion tests performed on ballasts extracted in 1965 5 and exposed to environmental conditions since that time

the southern hemisphere westerlies in the australasian sector over the last glacial cycle a synthesis abstract the southern hemisphere westerlies in the southwest pacific are known to have waxed and waned numerous times during the last two glacial cycles though even semi continuous histories of the westerlies extend back no more than about 20 000 years we have good evidence for at least three scales of events a westerly maximum occurs at the last glacial maximum there is less conclusive evidence for another westerly maximum in the late holocene and for a minimum at ca 11 ka it is too early to ascribe even a cycle to these data but there are grounds to suggest that milankovitch precessional forcing may underlie the observed pattern there is also a quasi 2600 year cycle present in antarctic ice cores that appears to correlate to variation in westerly flow there is strong centennial scale variability in historical times the little ice age lia ca 1400 1850 was associated with a poleward shift in the circumpolar trough in the southern ocean strengthened westerly circulation over tasmania and a strengthening of southwesterly circulation and neoglaciation in southern new zealand while the preceding period 800 1400 ad was less certainly marked by reduced westerly flow from modern records we know that decadal and inter annual variability is important e g pacific decadal oscillation high latitude mode also known as the antarctic oscillation el nino southern oscillation only a minority of the proxies examined can identify changes on these temporal scales but data from tree rings ice cores and laminated lake sediments do indicate systematic changes in these phenomena through time rossby wave patterns are shown to play a critical role in long duration events as well as at the synoptic scale we conclude that westerly circulation is as strong now as at any time in the last glacial cycle in addition changes in latitudinal boundaries in the westerlies may be nearly as large in inter annual zonal shifts ca 2 maximum as in glaciation interglaciation movements ca 3 4 there is however reasonable evidence of strengthening weakening across much of the westerly belt at westerly maxima minima such as the lia early holocene

do periglacial landscapes evolve under periglacial conditions polar and alpine periglacial areas are traditionally regarded as necessarily submitted to very efficient frost driven processes that control the holocene and ongoing geomorphic activity during the last decade the validity of this academic view has been increasingly questioned among the international scientific community the search for the real past and present processes responsible for landform evolution in cold nonglaciated areas is based mainly on more and more refined monitoring protocols relying upon sophisticated equipment to assess the representativeness and significance of monitoring data collected in restricted sites it appears necessary however to widen the perspective by adopting a twofold multiscale approach as proposed in the present paper 1 in space by integrating various scales from the general slope system to the bioclimatic nanoenvironment and 2 in time by taking into account the landscape history from tertiary inherited features to recent process changes induced by the contemporary warming reintegrating the historical approach should help both to place the ongoing processes within a succession and or combination of interoperating processes and to avoid misinterpretations of features considered wrongly as emblematic of frost action overall both the historical and monitoring approaches tend to reduce the geomorphic efficiency of frost derived processes instead the role of noncold related processes such as chemical thermal biogenic and rainfall induced ones is being emphasized of special interest would be an interdisciplinary discussion between geomorphologists and various disciplines of biological sciences including biochemistry and ecology studying processes of primary successions

field and laboratory experiments on high dissolution rates of limestone in stream flow abstract field and laboratory experiments were performed to examine dissolution rates of limestone in stream flow field experiments were conducted in three stream sites a c with different lithological or hydrological settings around a limestone plateau in the abukuma mts japan sites a and b are allogenic streams which flow from non limestone sources into dolines and site c has a karst spring source tablets made of limestone from the same plateau with a diameter of 3 5 cm and a thickness of 1 cm were placed in the streams for 3 years 2008 2011 where alkalinity ph and major cation concentrations were measured periodically the saturation indices of calcite sic of stream water were 2 8 0 4 at site a 2 5 0 4 at site b and 0 5 0 4 at site c annual weight loss ratios for tablets were extremely high at site a 0 11 0 14 mg cm 2 d 1 high at site b 0 05 mg cm 2 d 1 and low at site c 0 005 mg cm 2 d 1 the contrasting rates of weight loss are mainly explained by chemical conditions of stream water in addition laboratory experiments for dissolution of limestone tablets using a flow through apparatus revealed that flow conditions around the limestone tablet is another important factor for dissolution in the stream environment these results revealed that limestone dissolves at a rapid rate where water unsaturated to calcite continuously flows such as in an allogenic stream

a baroclinic mechanism for the eddy feedback on the zonal index a baroclinic mechanism for the positive eddy feedback on the zonal index is proposed the author considers the quasigeostrophic response of the zonally averaged flow to forcing by baroclinic eddies the transient response to eddy forcing is a largely barotropic acceleration of the westerly flow and a reduction of the baroclinicity at the latitudes of eddy generation but over time the action of surface drag leads to enhanced baroclinicity at these latitudes the steady state response has positive baroclinicity at the latitude of eddy generation if the eddies propagate away from this latitude before they dissipate this reinforcement of the low level baroclinicity provides a positive feedback if it is assumed that baroclinic eddies are generated more vigorously in regions of stronger low level baroclinicity the proposed mechanism explains observed and modeled features of zonal index variations the frequency and drag dependence of eddy feedback the bandedness in latitude of zonal wind variations and the tendency for anomalies in the zonally averaged zonal wind to drift poleward over time

response of baroclinic life cycles to barotropic shear abstract cyclonic barotropic shear of incrementally increasing magnitude is imposed on an idealized midlatitude jet and the life cycles of baroclinically unstable wavenumber 6 perturbations growing on these jets are studied when the barotropic shear parameter passes a critical value the life cycle makes an abrupt transition from anticyclonic to cyclonic behavior the abrupt transition in behavior is most evident in the barotropic decay of eddy kinetic energy in the structure of the eddies as seen in potential vorticity maps and in the nature of the zonal flow accelerations produced during the life cycle it is suggested that the abrupt transition can be interpreted as arising from a positive feedback between eddy propagation and eddy induced zonal flow accelerations dependences on the zonal scale of the eddy are also investigated wavenumber 8 exhibits cyclonic behavior while wavenumber 4 exhibits anticyclonic behavior for all values of cyclonic shear considered this dependence on zonal scale is c

from climatic to global change geomorphology contemporary shifts in periglacial geomorphology periglacial geomorphology developed in the 1940s 1960s as a branch of climatic geomorphology focusing first on quaternary studies and palaeoenvironmental reconstructions then on current geomorphi

ten years 1994 2004 of potential weathering in karkevagge swedish lapland this paper reports the findings of a ten year study of potential weathering of machine polished dolomite granite and limestone discs buried in shallow pits beneath a variety of vegetation cover types in karkevagge and on an adjoining ridge in swedish lapland the paper extends a previously published five year 1994 1999 record by adding the period 1999 2004 comparing the two periods and integrating results to provide a decadal record the field and laboratory procedures of the first period were faithfully replicated during the second period with the notable modification that only a segment of each original disc was replaced in the field for the second portion of the study a total of 48 dolomite 36 granite and 19 limestone discs were buried at shallow depths 60 cm beneath alpine tundra birch forest dryas heath heath meadow solifluction meadow and willow cover types with the exception of the willow which had only two each cover type had three replicated pits relationships identified during period 1 were generally repeated during period 2 salient results are the expected weathering rate order of limestone dolomite granite and statistically distinguishable differences in weathering rate by vegetation cover type differentiation of the two heath categories from the other vegetation cover types is the most important spatial distinction in weathering rate statistical distinctions among other measures were variable with soil horizon and burial depth being non significant ph variability being weakly distinguishable and drainage variability being important granite mass losses were generally too low to be useful for statistical separation dolomite discs experienced a statically higher loss rate during period 2 which had both a warmer and wetter air climate than period 1 minimum and maximum total decadal percentage losses from the discs were 0 2 and 25 7 for dolomite 0 07 and 0 57 for granite and 0 2 and 32 1 for limestone in general dolomite was the most useful material for monitoring mass loss with limestone weathering tending to be too rapid and granite weathering being too slow copyright 2006 john wiley sons ltd

left lateral active deformation along the mosha north tehran fault system iran morphotectonics and paleoseismological investigations abstract the mosha and north tehran faults correspond to the nearest seismic sources for the northern part of the tehran megacity the present day structural relationships and the kinematics of these two faults especially at their junction in lavasanat region is still a matter of debate in this paper we present the results of a morphotectonic analysis aerial photos and field investigations within the central part of the mosha and eastern part of the north tehran faults between the mosha valley and tehran city our investigations show that generally the traces of activity do not follow the older traces corresponding to previous long term dip slip thrusting movements the recent faulting mainly occurs on new traces trending e w to ene wsw affecting quaternary features streams ridges risers and young glacial markers and cutting straight through the topography often defining en echelon patterns right and left stepping these new traces correspond to steep faults with either north or south dipping directions along which clear evidences for left lateral strike slip motion are found at their junction zone the two sinistral faults display a left stepping en echelon pattern defining a positive flower structure system clearly visible near ira village further west the left lateral strike slip motion is transferred along the ene wsw trending niavaran fault and other faults the cumulative offsets associated with this left lateral deformation is small compared with the topography associated with the previous late tertiary thrusting motion showing that it corresponds to a recent change of kinematics

weathering implications of water chemistry in an arctic alpine environment northern sweden this paper reports on some of the chemical characteristics of late melt season water from karkevagge valley of the boulders above the arctic circle in northern sweden included in the analyses were temperature electrical conductivity ph so4 no3 k sio2 mg mn na fe and al these were measured in rain late lying snow and water from the major stream and lake as well as from pond tributary and seep sources in the valley a total of 71 samples was collected at 57 sites between august 6 and august 23 1996 for the purpose of characterizing the present weathering regime within this classic u shaped glacial valley evidence of chemical weathering included increases in solute concentrations over precipitation inputs and a source related wide variation in water chemistry the dominant anion measured in surface water was so4 that along with the presence of caso4 coatings on streambeds indicates that pyrite oxidation may contribute to the weathering regime high so4 concentrations were associated with gypsum coated streambeds and seeps that emerge from the bedrock low so4 concentrations were associated with tributaries flowing primarily on fresh rock and originating from melting snow estimated chemical denudation rate for the valley corrected for atmospheric inputs was 19 2 tons km2 yr although this is lower than previously reported our research supports earlier work indicating that chemical weathering is a major component of mass wasting in this arctic alpine environment

a climatology of rossby wave breaking on the southern hemisphere tropopause abstracta 30 yr climatology of rossby wave breaking rwb on the southern hemisphere sh tropopause is formed using 30 yr of reanalyses composite analysis of potential vorticity and meridional fluxes of wave activity show that rwb in the sh can be divided into two broad categories anticyclonic and cyclonic events while there is only weak asymmetry in the meridional direction and most events cannot be classified as equatorward or poleward in terms of the potential vorticity structure the position and structure of the fluxes associated with equatorward breaking differs from those of poleward breaking anticyclonic breaking is more common than cyclonic breaking except on the lower isentrope examined 320 k there are marked differences in the seasonal variations of rwb on the two surfaces with a winter minimum for rwb around 350 k but a summer minimum for rwb around 330 k these seasonal variations are due to changes in the location of the tropospheric jets and dynamical tropopause during winter the

the chemical weathering regime of karkevagge arctic alpine sweden abstract karkevagge is a valley located in swedish lapland at approximately 68 n and represents an arctic alpine landscape it is a presently periglacial glaciated trough incised into essentially horizontal metamorphic rocks some of which are presumably pyrite rich a set of coordinated studies was undertaken to investigate the nature of chemical weathering and pedogenesis in the valley and upon the abutting ridges august 1996 water quality measures reveal considerable spatial variation in solute totals with the highest total dissolved solute abundances being correlated with high sulfate abundances ridge crest soils exhibited poor horizonation but more extensive development of secondary clay minerals developed in situ than was found in valley flank and valley bottom soils valley soils exhibited multiple thin horizons many of which were buried and are taken to reflect great paraglacial and periglacial instability favorable microenvironments in the valley permit significant development of spodosols coarse debris along and across the valley bears both weathering rinds and rock coatings rock coatings in the valley include several types of iron films sulfate crusts carbonate skins and heavy metal skins karkevagge represents a mild arctic environment which does not preclude substantial chemical weathering in locations where abundant pyrite rich bedrock and water coincide this weathering follows pathways which are eminently expectable given that weathering of the pyrite rich rock permits generation of sulfuric acid which in turn weathers muscovite mica and calcite in local schists and marble respectively zones of intense chemical weathering also generate clearly visible deposits of gypsum and iron sulfate deposits such as jarosite not all arctic and or alpine environments are likely to be so active chemically but the results from karkevagge clearly show that dismissal of chemical weathering in cold regions on the basis of presumed first principles is erroneous consequently chemical weathering in such environments merits substantially more attention than it has hitherto received

rossby wave breaking in the southern hemisphere wintertime upper troposphere abstract the characteristics of rossby wave propagation and breaking in the southern hemisphere upper troposphere during winter are examined although the southern hemisphere subtropical jet is more zonally symmetric than that of the northern hemisphere there are still significant zonal variations in the upper tropospheric flow in particular the flow within a given sector 120 longitude can generally be characterized into one of four different configurations i a single jet ii a broken subtropical jet iii a polar jet at the upstream end of the subtropical jet or iv a polar jet at the downstream end of the subtropical jet using potential vorticity thinking and barotropic wind shear arguments it is argued that the characteristics of the rossby wave propagation and breaking will differ between each flow configuration consistent with these arguments examination of potential vorticity maps and contour advection calculations show differing wave breaking characteristics in particular t

is the atmospheric zonal index driven by an eddy feedback abstract the authors address the question of whether or not eddy feedback plays an important role in driving the anomalous relative angular momentum associated with the zonal index zi in the atmosphere for this purpose composites of anomalous relative angular momentum and anomalous eddy angular momentum flux convergence eddy forcing are examined with national centers for environmental prediction national center for atmospheric research reanalysis data by using an empirical orthogonal function analysis it is found that zi behavior dominates the summer season of both hemispheres and also the winter season of the southern hemisphere for the summer season the zi is characterized by meridional displacements of the midlatitude eddy driven jet and for the southern hemisphere winter it is characterized by a simultaneous movement of the subtropical and eddy driven jets in the opposite direction for the zi of each of the above seasons unfiltered eddy forcing did not exhibit a prominent eddy feedback h

diabatic damping of zonal index variations abstractzonal index variations or north south shifts of the midlatitude jet are the dominant mode of zonal wind variability in the southern hemisphere previous studies have shown that synoptic time scale eddy momentum flux provides a positive feedback and acts to increase the persistence and low frequency variance of the zonal index however the impact of diabatic heating due to the precipitation associated with these eddies has not been investigated in this study regression analyses have been conducted to demonstrate that a robust precipitation anomaly can be found to accompany the jet and eddy momentum flux anomalies associated with a poleward shift of the jet with enhanced precipitation on the poleward flank of the jet and reduced precipitation on the equatorward flank diabatic heating associated with such a precipitation anomaly is expected to reduce the temperature gradient across the jet anomaly thus decreasing eddy generation and damping the anomaly this expectation is confirmed by three

weathering rates of buried machine polished rock disks karkevagge swedish lapland some 48 dolomite 37 granite and 19 limestone machine polished disks were buried at soil horizon boundaries in 16 soil pits to maximum depths of 0 5 0 6 m within karkevagge a presently periglacial glaciated trough in arctic sweden the objective of the ongoing study is to determine near surface potential weathering rates beneath birch forest dryas heath heath meadow solifluction meadow and willow vegetation cover types selected disks were excavated after 1 year and all disks were excavated after 4 or 5 years the limestone disks weathered fastest followed closely by the dolomite disks but the granite disks weathered at much slower rates mean annual percentage mass loss over 4 or 5 years was 0 473 0 145 two standard errors for dolomite disks 0 032 0 005 two standard errors for granite disks and 1 104 0 446 two standard errors for limestone disks for dolomite disks the dryas heath and heath environments weathered the most slowly a trend that was generally followed by the granite disks poor drainage i e increasing wetness and decreasing ph were found to promote dolomite weathering rates in a statistically significant manner surficial and subsurface weathering rates at individual sites were generally found to be correlated for dolomite but not granite copyright 2002 john wiley sons ltd

observations simulations and dynamics of jet stream variability and annular modes the characteristics of the dominant pattern of extratropical variability the so called annular modes are examined in the context of the theory that eddy driven jets are self maintaining it is shown that there is genuine hemispheric symmetry in the variation of the zonal wind in the southern hemisphere but not the northern hemisphere the annular mode is shown to be baroclinic in nature it is associated with changes in the baroclinic eddy source latitude and the latitude of the eddy source region is organized by the mean flow this behavior is expected if there is a baroclinic feedback that encourages the maximum baroclinic instability to be coincident with the maximum zonal wind speed and discourages the meridional vacillation of the eddydriven jet stream it is shown that the strength of the thermally indirect circulation that gives rise to the baroclinic feedback appears to influence the time scale of the annular mode when the thermally indirect circulation is stronger the annular mode has a longer e folding time in a simplified gcm preliminary results indicate that the same dynamics are important in the real atmosphere

multiple regimes and low frequency oscillations in the northern hemisphere s zonal mean flow this paper studies multiple regimes and low frequency oscillations in the northern hemisphere zonal mean zonal flow in winter using 55 yr of daily observational data the probability density function estimated in the phase space spanned by the two leading empirical orthogonal functions exhibits two distinct statistically significant maxima the two regimes associated with these maxima describe persistent zonal flow states that are characterized by meridional displacements of the midlatitude jet poleward and equatorward of its time mean position the geopotential height anomalies of either regime have a pronounced zonally symmetric component but largest amplitude anomalies are located over the atlantic and pacific oceans high frequency synoptic transients participate in the maintenance of and transitions between these regimes significant oscillatory components with periods of 147 and 72 days are identified by spectral analysis of the zonal flow time series these oscillations are described by singular spectrum analysis and the multitaper method the 147 day oscillation involves zonal flow anomalies that propagate poleward while the 72 day oscillation only manifests northward propagation in the atlantic sector both modes mainly describe changes in the midlatitude jet position and intensity in the horizontal plane though the two modes exhibit synchronous centers of action located over the atlantic and pacific oceans the two persistent flow regimes are associated with slow phases of either oscillation

a pv view of zonal flow vacillation abstract it is suggested here that the zonal flow vacillation of the southern hemisphere is caused by a mutual interaction between the barotropic shear of the zonal flow and the evolution of baroclinic eddies during the later stages of their lifecycle an index of the zonal wind anomaly difference between 40 and 60 s is defined for a 13 yr record of european centre for medium range weather forecasts ecmwf analyses periods are selected during which the zonal flow is at the extremes of its characteristic vacillation which are distinguished by a broad westerly jet with minor maxima near 30 and 60 s and a narrower jet peaked near 40 s the narrower 40 s jet has stronger cyclonic shear across the baroclinic zone these changes are accompanied by shifts in poleward eddy momentum flux on the 500 hpa surface and potential vorticity fluxes on the theta surfaces that lie in the midtroposphere which are both consistent with the maintenance of the zonal wind anomalies against friction series of synoptic maps