multi proxy holocene palaeoclimate records from walton moss northern england and dosenmoor northern germany assessed using three statistical approaches abstract plant macrofossil analysis is a robust and established method for estimating palaeoclimatic changes from raised peat bogs there remains uncertainty however over the best statistical method to use for converting the palaeoecological data to an index of bog surface wetness bsw to test this a 9 m core wlm22 from walton moss northern england was analysed for changes in plant macrofossils testate amoebae and humification the plant macrofossil data were then converted to a single curve of bog surface wetness bsw using three different techniques weighted averaging by the dupont hydroclimatic index dhi and ordination by detrended correspondence analysis dca and by non metric multidimensional scaling nmds through comparison with testate amoebae and humification data from the same core it was observed that a statistically better fit was found with the wetness curve from dhi than that from either ordination it is suggested that the weighted averaging method of dhi can provide a good indicator of bsw variation in long peat records where the profile incorporates data from both sphagnum dominated and eriophorum ericaceous dominated bog deposits which is common to nw european bogs the data also imply that with sufficient diversity of taxa there is potential for the further development of plant macrofossil transfer functions application of dhi to an additional data set from dosenmoor northern germany and comparison with published records from nw europe revealed coherent regional climatic variations

holocene palaeoclimates from peat stratigraphy macrofossil proxy climate records from three oceanic raised bogs in england and ireland quantified analyses of plant macrofossil remains have been made from three profiles of peat from raised bogs spanning a distance of 425 km from western ireland to northern england the reconstructed vegetation of each profile is related to changing bog surface wetness bsw and since the bogs are ombrotrophic these bsw changes are interpreted in terms of changing climate using age depth models based on a total of 49 radiocarbon dates a number of wetter and drier phases are identified and phase shifts to wetter and or cooler climates are defined prominent coincident changes to wetter conditions are dated in at least two of the profiles to ca 4400 4000 1750 1400 and 1000 cal bp and in all three profiles at 3200 2750 2350 2250 and around 700 cal bp these phases are related to proxy climate changes in other terrestrial data sets from northwest europe and a broad degree of synchroneity is demonstrated

a study on wind driven circulation in the subarctic north pacific using topex poseidon altimeter data time dependent wind driven circulation in the subarctic region in the north pacific is investigated by using topex poseidon t p altimeter data and european centre for medium range weather forecasts ecmwf wind data for about 2 years the first empirical orthogonal function eof of the sea level anomaly sla without the variation related to the steric height change sla represents a basin sized oscillation which is associated with the spin up and spin down of the subarctic gyre moreover the time series of the first eof corresponds to the oyashio current variation measured by the moored current meter at about 1250 m depth the first and third eofs of the wind stress curl fields represent basin sized south north oscillations being associated with changes in intensity and the latitudinal position of the aleutian low time series of both the dominant eofs of the sla and the wind stress curl anomaly are correlated well which suggests that dominant variation of the sla is mainly controlled by the wind stress curl fields represented by the first and third eofs the time series of the first eof of the sla is in agreement with that of sverdrup transport estimated by the wind stress curl near 40 n with a correlation of 0 70 both standard deviations of the t p sla derived transports in the interior and the western boundary regions are consistent with that of the sverdrup transport in the same order of magnitude these results suggest that sea surface height variation in the subarctic north pacific is approximately explained by the time dependent wind driven circulation

contributions of wind forcing waves and surface heating to sea surface height observations in the pacific ocean the dominant processes affecting sea surface height ssh variability observed by the topex poseidon altimeter vary regionally in the pacific baroclinic rossby waves equatorially trapped kelvin waves steric response to seasonal heating and the response to wind stress curl forcing are all important the steric response to surface heating dominates seasonal ssh variability in the subpolar gyre and the eastern subtropical gyre south of the kuroshio extension and south of 20 n in the eastern pacific the dominant contribution to ssh is from near annual period rossby waves to quantify the wave energy observed ssh was assimilated into a kinematic model of westward propagating waves these waves account for 70 of ssh variance between 10 s and 10 n but only 30 between 10 n and 30 n although wave energy in the eastern pacific is correlated with ssh anomalies at the equator the much larger wave energy in the western pacific is correlated with wind stress curl suggesting that the rossby waves there are locally forced in addition to these planetary waves the ocean response to wind forcing via ekman pumping is observed in several places specifically in the north equatorial current a quasi steady topographic sverdrup balance is detectable over most of the north pacific at latitudes as low as 10 15 n as well as in the south pacific where it is seen north of 50 s the decomposition of the ssh signal into propagating waves an ekman pumping response and sverdrup transport is consistent with the results from an isopycnal numerical model

anthropogenic pb component in hydrothermal ochres from marsili seamount tyrrhenian sea abstract recent hydrothermal fe oxyhydroxide precipitates ochres were sampled during two submersible expeditions to the ne part of the marsili seamount summit se tyrrhenian sea the marsili ochres belong to type 1 primary sulfide poor fe oxyhydroxides according to the classification of hekinian et al hekinian r hoffert m larque p cheminee j l stoffers p bideau d 1993 hydrothermal fe and si oxyhydroxide deposits from south pacific intraplate volcanoes and east pacific rise axial and off axial regions econ geol 88 2099 2121 they are x ray amorphous highly metalliferous al al mn fe 0 4 low in si transition metals co ni cu zn pb and rare earth elements ree and enriched in b v and mo their chemical composition and ree distribution patterns indicate precipitation from low temperature hydrothermal fluid mixed with seawater measured pb isotope compositions in the ochres indicate that the pb is dominantly anthropogenic in origin by contrast the pb isotope ratios in the nearby higher temperature hydrothermal deposits from the panarea arc volcano show that the pb is derived mainly from local volcanic rocks the fact that the pb isotopic signature of the marsili ochres is controlled by recent anthropogenic input suggests that the fe oxyhydroxides precipitated from fluids depleted in transition metals the low 206pb 207pb ratios in the ochres reflect the contribution of pb from australian ores indicating precipitation of the ochres somewhere between present day and the beginning of australian pb import to europe the young age of the ochres and the presence of other hydrothermal deposits along the marsili crest suggest that the magmatic chamber beneath the seamount may still be alive this study represents the first observation of anthropogenic influence on submarine hydrothermal deposits

a multiproxy approach to reconstructing surface wetness changes and prehistoric bog bursts in a raised mire system at derryville bog co tipperary ireland multiproxy analyses comprising peat stratigraphy testate amoebae pollen and humification analyses from four profiles across a complex raised mire system at derryville bog co tipperary ireland are used to demonstrate the surface wetness changes covering the period cal bc 1500 to cal ad 1000 with special reference to a series of bog bursts identified within the stratigraphic record comparison of the proxies reveals varying levels and forms of response to the bursts depending on the size of the burst and the relative location of the site and reinforces the necessity for such detailed studies in reconstructing the full palaeohydrological history of large and complex sites because of the heavily cut over nature of the bog the availability of extensive sections from which peat stratigraphic data can be obtained also reinforces the inherent weakness in relying on coring data when trying to understand the complex structure of such large systems

large scale response of the ocean to atmospheric forcing at low frequencies estimates of the time dependent sea surface topography on large space 500 2500 km and time 30 days to 2 years scales from altimetry and tide gauge data are compared with estimates of the surface meteorological fields winds and pressure on the same scales the comparisons are made in the north pacific and north atlantic despite the obvious remaining high noise level in the sea surface topography there is a significant correlation between the atmosphere and the time varying ocean circulation these relations are quantified using simple multichannel regression models with no time lags typically 50 of the sea level variance can be described by the wind curl and divergence and the pressure field some areas produce classical static inverted barometer effects but others suggest an amplified response the motions are believed to characterize most of the water column

on the wind forcing of bottom pressure variability at amsterdam and kerguelen islands southern indian ocean 1 bottom pressure records from amsterdam and kerguelen islands southern indian ocean were collected between 1986 and 1989 and interpreted previously in terms of volume transport fluctuations between the islands vassie et al 1994 since a substantial portion of the mean transport of the antarctic circumpolar current acc flows between the islands it was assumed that acc transport variability was the predominant signal being measured and comparisons with acc variability at other longitudes were made here we examine the relationship between atmospheric forcing and observed bottom pressure variability we find that kerguelen bottom pressure is forced predominantly by wind stress curl over the kerguelen plateau for periods between around 5 days and 1 year a weaker correlation with circumpolar eastward winds is observed but is seen not to be causal amsterdam pressure shows a similar local response to curl for high frequencies 5 10 days but at longer periods is sensitive to curl over the sub basin between kerguelen plateau the southeast indian ridge and antarctica this is the region of long wavelength sea level variability observed by chao and fu 1995 and interpreted in terms of a geostrophic resonance by webb and de cuevas 2002a altimetric studies confirm the usefulness of the amsterdam location in monitoring this mode we conclude that the amsterdam kerguelen pressure difference is not a useful measure of acc transport variability and that previous agreement found between variability observed here and other locations is largely fortuitous instead the series separately reflect different important dynamical modes in the southern indian ocean

radiocarbon dating of a recent high latitude peat profile stor amyrân northern sweden the value of both high precision hp and ams 14c determinations in the fine resolution dating of recent peat at stor amyr n near umea northern sweden has been explored a detailed chronology of accumu lation based on 14c an occurrence of the askja ad 1875 tephra and 241am measurements has been derived for the last 700 years this shows significant changes in the mass balance of the peat profile with minimum rates of net carbon sequestration overlapping with the period of minimum spring and summer temperature documented by published tree ring evidence the paper presents a methodology for calculating empirically past changes in the rate of net carbon sequestration in boreal peatlands and for exploring the effects of climatic variations and possible future global warming on these rates

dynamics of the wind driven sea level variation around antarctica coastal sea level variation around antarctica is characterized by a coherent circumpolarly in phase fluctuation correlated with the antarctic oscillation aao this study addresses the dynamics of the winddriven sea level variation around antarctica a realistic barotropic numerical model reproduced well the observed sea level around antarctica from numerical model experiments the authors demonstrate that the forcing responsible for the coastal sea level is the wind stress at the coastal boundary both the dominant coherent signal and westward propagating signals are identified in the model and these signals are trapped over the shelf and slope around antarctica as a mechanism of these trapped signals the authors consider analytical solutions of the oceanic response to alongshore wind stress over the shelf and slope in the circumpolar domain in these solutions besides the shelf wave mode a wavenumber zero mode appears and characterizes the coastal dynamics around antarctica at periods from 10 to 200 days the coherent sea level can be explained quantitatively by the solution of this wavenumber zero mode with a 5 10 day damping time scale the spectral peaks of the westward propagating signals can be explained by the resonance of the shelf wave mode the wavenumber zero mode can respond to the wavenumber zero forcing at any frequency and the degree of response increases with decreasing frequency in addition the wavenumber zero component of wind stress corresponding to the aao variation is a dominant forcing therefore the coherent sea level variation around antarctica is preferably generated and becomes a dominant feature in the circumpolar domain particularly at lower frequencies

the climate of scotland over the last 5000 years inferred from multiproxy peatland records inter site correlations and regional variability the mid to late holocene climates of most of scotland have been reconstructed from seven peat bogs located across north south and east west geographical and climatological gradients the main techniques used for palaeoclimatic reconstruction were plant macrofossil colorimetric humification and testate amoebae analyses which were supported by a radiocarbon based chronology aided by markers such as tephra isochrons and recent rises in pine pollen and in spheroidal carbonaceous particles scps field stratigraphy was undertaken at each site in order to show that the changes detected within the peat profiles were replicable proxy climate records were reconstructed using detrended correspondence analysis dca of the plant macrofossil data and a mean water table depth transfer function on the testate amoebae data these reconstructions coupled with the humification data were standardised for each site and used to produce a composite record of bog surface wetness bsw from each site the results show coherent wet and dry phases over the last 5000 years and suggest regional differences in climate across scotland specifically between northern and southern scotland distinct climatic cycles are identified all of which record a millennial scale periodicity which can be correlated with previously identified marine and ice core holocene cycles the key role of the macrofossil remains of sphagnum imbricatum a taxon now extinct on many sites is discussed in relation to the identified climatic shifts

solar forcing of climatic change during the mid holocene indications from raised bogs in the netherlands two cores of mid holocene raised bog deposits from the netherlands were 14 c wiggle match dated 14 c as a proxy for changes in solar activity is validated this paper adds to the increasing body of evidence that solar variability forced climatic changes during the holocene 14 c wiggle match dating mid holocene wet shifts

departures from the local inverse barometer model observed in altimeter and tide gauge data and in a global barotropic numerical model sea level data from the topex poseidon altimeter satellite and from subsets of the global tide gauge and bottom pressure recorder networks have been employed to study the worldwide distribution of departures from the simple local inverse barometer lib model from a combination of measurement techniques the lib model was found to provide a reasonable representation of the data within 5 10 outside of the tropics for timescales from several days to several weeks for most locations however several parts of the southern ocean and other higher latitude areas were seen from the altimetry to contain significant departures across the range of timescales accessible for study by the technique within the tropics the response of sea level to air pressure forcing was observed to be typically 50 of that of the lib model at timescales of several days with considerable spatial variation and to approximate the lib model more closely at timescales of several weeks a coarse grid global barotropic numerical model was found to reproduce qualitatively the global average response as a function of frequency to simulate many of the characteristics of the spatial variation of the response and to demonstrate the relative importance of air pressure and wind forcing at different timescales data sets from the permanent service for mean sea level and u k meteorological office were used to investigate lib departures at intraseasonal and longer timescales along continental coastlines and at ocean islands increasingly large departures were observed along many parts of the world coastline as timescales increased from months to seasons

last millennium palaeoenvironmental changes from a baltic bog poland inferred from stable isotopes pollen plant macrofossils and testate amoebae the baltic coast of northern poland is a region of considerable potential interest for paleoclimatic studies because this region is under the influence of both oceanic and continental climates and that these two influences have likely changed through time also unlike many more intensively studied regions of europe human impact was more limited until the 19th century we present a multiproxy high resolution record from st zki mire an ombrotrophic mire located in northern poland 35 km from the baltic sea coast we combined four proxies from the peat testate amoebae stable isotopes 13c of sphagnum stems pollen and plant macrofossils supported by dendroecological data to assess the palaeoenvironmental changes that took place during the last millennium the general aim of this study was to test if a range of proxies testate amoebae pollen plant macrofossils and tree rings could allow inferring a climatic signal from a peat monolith despite the considerable anthropogenic impact on the pomerania landscape since the early medieval period combining internal e g macrofossils and testate amoebae and external pollen signals is key to distinguishing human from climatic signals in palaeoenvironmental studies of peatlands our more specific aims were to a reconstruct the last millennium palaeoenvironment in a baltic raised bog and its surroundings b identify the major wet dry shifts and correlate those events with climate change and human impact c assess the resilience of the baltic bog ecosystem following human impact we noted two disturbance periods in the history of the mire the two major disturbances in the history of the mire were dry periods i 1100 1500 ad and ii 1650 1900 2005 ad these are reflected in all indicators and can be interpreted as the mixture of climate impact and human activities however the pollen record shows little evidence of human indicators during the first dry shift the second disturbance can be related to local peat exploitation of the mire and then in the 20th century with limited artificial drainage from 1500 ad all proxies show that the water table abruptly rose in the mire the beginning of this shift occurred during the little ice age and therefore it is likely a climatic signal alternatively this wet shift could have been interpreted as a re wetting mire surface after peat burning but this interpretation is rejected because there is no evidence of major local fire in the macrofossil record the macrofossil data shows that sphagnum fuscum dominated the pristine mire vegetation but then declined and finally disappeared this pattern is comparable with the timing of extinction of sphagnum austinii in western europe this study illustrated the value of palynological analysis of peat archives especially for last millennium to assess the magnitude of anthropogenic land use changes for example the comparison of fagus beech and carpinus hornbeam history with the palaeohydrological record allowed us to exclude climate change as the most important factor for the decline and expansion of these tree species this study is the first direct comparison of testate amoeba and stable isotope data

mire development pathways and palaeoclimatic records from a full holocene peat archive at walton moss cumbria england plant macrofossil data have been used to identify the successive mire communities occupying both central and marginal locations in the walton moss peatland complex during the last 10 500 years the reconstructed pathways of mire development indicate that early holocene fen and fen carr communities were succeeded by species indicative of deep mire water tables and oligotrophic conditions the character of the fen bog transition fbt is compared with similar records of peatland development from britain and scandinavia and with independent climate data for the early holocene the pseudohochmoor of central europe is suggested as an approximate modern analogue for the dry pioneer oligotrophic mire type and alternative explanations for its presence are explored the first major increase in ombrotrophic sphagna occurred at c 7800 cal bp overlying sphagnum peats provide a continuous record of climate change inferred from fluctuations in raised mire surface wetness the proxy palaeoclimate record reconstr

the relationship between deep ocean currents and winds east of barbados abstract observations of currents collected at the polymode array iii cluster c 16 n 54 w are compared with radiosonde winds measured at barbados 13 n 62 w using a linear response analysis the winds and the currents are coherent throughout the water column 5400 m over the subinertial frequency range of 0 025 to 0 25 cpd the coherence is highest between the east west wind stress and north south currents over smooth topography the wind related ocean currents have a rms of 2 5 cm s 1 at 500 m and 1 1 cm s 1 at 4000 m and account for approximately one third of the total eddy kinetic energy the wind current phase is depth independent and does not vary significantly over the 200 km horizontal scale of the array the response amplitude is surface intensified and increases with decreasing frequency which is consistent with a deterministic theoretical model the coherence values and response estimates suggest an off resonant barotropic response to large scale wind forcing

evidence of time dependent sverdrup circulation in the south pacific from the seasat scatterometer and altimeter abstract seasat scatterometer and altimeter data are analyzed to investigate time dependent sverdrup dynamics in the southern ocean 40 s to 60 s over seasonal time scales sverdrup dynamics are shown to be inadequate to describe the circulation in the south atlantic and indian oceans the sverdrup circulation in the south pacific is reasonable north of 55 s the changes in sverdrup circulation from july to september 1978 indicate an eastward acceleration along 55 s and westward acceleration along 40 s suggesting a southward shift in the subpolar eastward flow sea level in the south pacific is estimated for july and september 1978 from scatterometer vector wind data based on sverdrup dynamics assuming a flat bottom ocean with barotropic flow the changes in sverdrup sea level are compared with the changes in sea level observed by the altimeter for the same time period both estimates indicate a rise in sea level along a zonal band centered at about 50 s this sea level rise inferred from both the scatt

sensitivity of west and central european river systems to environmental changes during the holocene a review abstract sediment deposition in floodplains is an essential part of the sediment dynamics of a catchment these sediment dynamics can vary largely on a holocene time scale under the influence of driving forces such as land use and climatic variations in this paper we review the holocene floodplain sediment deposition history of rivers in west and central europe with special attention to the influence of climate and land use variability during the early holocene preboreal to atlantic period most floodplains were rather stable with limited floodplain aggradation after this initial phase of relative stability sedimentation rates increase during the middle and late holocene with often the most important deposition phase during the last 1000 to 2000 a the start of the increase in sedimentation varies spatially with an earlier start in the west france germany then in the east poland belarus ukraine while there are also local differences between regions which are settled early e g loess regions compared to later settled regions the sedimentation history of most floodplains can be linked to the local land use history while influence of climatic variations on floodplain aggradation is often reported to be of minor importance processes related to bedload are often reported to be more influenced by climatic events relationships between the driving forces and the sediment history are mainly based on synchronicity and there is seldom proof for a direct causal relationship future research should focus on a system based approach integrating the floodplain deposition in the entire sediment dynamics which includes also erosion colluvial deposition and export main research questions that need further attention include integration of system based concepts like landscape connectivity and buffering effects and also the assessment of the individual contribution of land use changes and climatologic variations on the sediment dynamics detailed sediment budget studies combined with modeling studies can make an important contribution to the understanding of floodplain sediment dynamics

a note on the barotropic response of sea level to time dependent wind forcing this study examines the extent to which sea level variations at periods between 30 days and 1 year and spatial scales greater than 1000 km can be described by the wind driven linear barotropic vorticity dynamics the topex poseidon altimetric observations of sea level and the wind products of the national meteorological center are used as the database for the study each term of the linear barotropic vorticity equation was evaluated by averaging over regions of 10 10 in most of the open ocean the result of the analysis suggests that the sea level variabilities at the scales considered cannot be fully described by the equation the apparent net vorticity change is more than what can be explained by the local wind stress curl in the few regions where the wind stress curl is strong enough to balance the vorticity budget predominantly in the northeast pacific and the southeast pacific the balance is basically achieved in terms of the time dependent topographic sverdrup relation namely the balance between the advection of the planetary vorticity plus the topography induced vorticity and the forcing by the wind stress curl

the barotropic electromagnetic and pressure experiment 1 barotropic current response to atmospheric forcing during 1986 1987 an array of horizontal electrometers which measure the subinertial barotropic velocity was deployed for 11 months in the central north pacific to study atmospherically forced motions in a low eddy kinetic energy region significant coherence is found to be ubiquitous between the barotropic velocity and one or more surface atmospheric variables over the north pacific the maximum squared coherence between currents and wind stress curl at all periods greater than 3 days is typically 0 6 rarely below 0 4 and occasionally above 0 8 and is dominantly nonlocal although local coherence is seen at some sites especially at the shorter periods both the coherence and the intersite pattern similarity are strongest at the periods of relative maxima in the barotropic current autospectra e g at 6 8 10 14 and 20 50 days the locations at which the wind stress curl forces the motions at each site and for each period have been determined while there is substantial intersite variability some of the observed patterns of squared coherence over the north pacific are very similar to those predicted by simple linear smooth bottomed quasi geostrophic models of atmospherically forced barotropic currents the forcing location is occasionally found to be the same spot for all oceanic instruments especially at the autospectral maxima in barotropic current more commonly distinct forcing locations are found for each instrument even when closely spaced suggesting topographic influence in other cases multiple forcing locations are implicated for the motions at a single station all of this site and period dependent variability of the forcing location is incompatible with the simple models and is due either to the known spatial inhomogeneity of the curl forcing field or to topographic effects the importance of the former is emphasized using simple arguments based on analytic transfer functions between the atmospheric and oceanic variables and on observed wavenumber spectra for wind stress curl quantitative assessment of topographic effects must await suitable numerical models in addition maximum likelihood wavenumber spectra of the barotropic currents have been estimated in those bands with an adequate number of coherent sensors the wavenumbers at the spectral peaks are compatible with the dispersion relation for rossby waves modified by the observed large scale linearly sloping topography which shoals to the northeast the observed group velocities are in general quite consistent with the inferred forcing locations based on the ocean atmosphere coherences

wind forcing of the atlantic thermocline along 32 n at low frequencies abstract the bermuda tide gauge record extends back to the early 1930s that sea level fluctuations there are highly coherent with dynamic height from hydrographic data has two interesting implications first it should contain information about the low frequency circulation of the atlantic furthermore because dynamic height contains information on heat storage it might on the limited timescales accessible in the record also contain clues about climate a simple model of wind forcing of the atlantic from the african coast to bermuda uses the levitus mean density data to estimate the long rossby wave speed as a function of longitude sea level and thermocline variability estimated this way are in remarkably good agreement with observations at periods of more than a few years duration the peak to peak sea level signal is 18 cm which is nearly 25 of the slope across the gulf stream at this latitude the model results suggest that the variability is largest somewhat to the east of bermuda fluctuatio

25 day period large scale oscillations in the argentine basin revealed by the topex poseidon altimeter the measurement of the global sea surface height made by the topex poseidon satellite has provided the first synoptic view of large scale oceanic variability at intraseasonal scales from weeks to months areas of significant intraseasonal variability were found primarily in the tropics and the high latitude oceans the southern ocean in particular the focus of the paper is the finding of large scale oscillations at a period of 25 days in the argentine basin of the south atlantic ocean these oscillations exhibit a dipole pattern of counterclockwise rotational propagation centered at 458s 3178e over the zapiola rise the scale of the dipole is about 1000 km the peak to trough amplitude is on the order of 10 cm the amplitude of these oscillations has large seasonalto interannual variations these oscillations are shown to be associated with a free barotropic mode of the basin as a solution to a linearized barotropic vorticity equation closed f h contours provide a mechanism for the confinement of the waves to the topographic feature of the zapiola rise results from a numerical model simulation reproduced the patterns of the observed oscillations the resultant mass transport variability is on the order of 50 sv sv 106 m3 s21 deep current meters in the argentine basin reveal signals consistent with the altimetry observations

holocene evolution of a lowland scottish landscape kirkpatrick fleming part i peat and pollen stratigraphic evidence for raised moss development and climatic change this series of papers addresses the principal natural and anthropogenic environmental changes that have transformed a typical lowland scottish landscape during the holocene sediment and pollen stratigraphic techniques together with radiocarbon dating are applied in this paper to the stratigraphy of a raised bog at burnfoothill moss eastern dumfriesshire to deduce changes in groundwater levels within the bog and by inference changes in effective precipitation the basin initially a shallow pond was rapidly colonized by fen peat at 9600 bp possibly during a phase of drier climate which ended at c 8700 bp short lived fluctuations in bog surface wetness are identified before a major change to a wetter bog surface at around 7700 cal bp representing the transformation from fen peat to raised moss anthropogenic interference with surrounding woodland is believed to have destabilized the water balance within the peat drier bog surface conditions occur at c 6700 cal bp and a shift to a wetter

ocean dynamics associated with rapid j2 fluctuations importance of circumpolar modes and identification of a coherent arctic mode 1 fluctuations of the earth s dynamic oblateness j2 are a measure of global redistributions of mass between equatorial and polar regions sensitive to the component which is symmetric about the equator cox and chao recently published a time series of monthly values of j2 based on satellite orbit determination which showed rapid fluctuations from month to month as well as a large change in j2 in 1997 1998 we here investigate the ocean dynamics associated with these rapid fluctuations using a barotropic ocean model forced by atmospheric wind stress and pressure we find that the model has significant skill in reproducing the observations though not the change in 1997 1998 much of the model variability is related to coherent circumpolar fluctuations in arctic and antarctic bottom pressure which despite their apparent symmetry are forced by quite different mechanisms the antarctic mode is forced by circumpolar winds whereas the arctic mode is forced by northward winds over the entrances to the polar sea comparison with in situ observations shows that the model has skill in reproducing the polar modes arctic tide gauge records confirm the presence of a coherent mode at short periods and at long periods over at least the eurasian arctic shelf if barotropic and representative of the whole arctic this would be large enough to make a major contribution to measured j2 fluctuations but does not account for the 1997 1998 event

long term and seasonal caspian sea level change from satellite gravity and altimeter measurements we examine recent caspian sea level change by using both satellite radar altimetry and satellite gravity data the altimetry record for 2002 2015 shows a declining level at a rate that is approximately 20 times greater than the rate of global sea level rise seasonal fluctuations are also much larger than in the world oceans with a clearly defined geographic region and dominant signal magnitude variations in the sea level and associated mass changes provide an excellent way to compare various approaches for processing satellite gravity data an altimeter time series derived from several successive satellite missions is compared with mass measurements inferred from gravity recovery and climate experiment grace data in the form of both spherical harmonic sh and mass concentration mascon solutions after correcting for spatial leakage in grace sh estimates by constrained forward modeling and accounting for steric and terrestrial water processes grace and altimeter observations are in complete agreement at seasonal and longer time scales including linear trends this demonstrates that removal of spatial leakage error in grace sh estimates is both possible and critical to improving their accuracy and spatial resolution excellent agreement between grace and altimeter estimates also provides confirmation of steric caspian sea level change estimates grace mascon estimates both the jet propulsion laboratory jpl coastline resolution improvement version 2 solution and the center for space research csr regularized are also affected by leakage error after leakage corrections both jpl and csr mascon solutions also agree well with altimeter observations however accurate quantification of leakage bias in grace mascon solutions is a more challenging problem

sea level comparison between topex poseidon altimetric data and a global ocean general circulation model from an assimilation perspective the topex poseidon altimetric sea level observations during 1993 are used to validate a simulation made by the laboratoire d oceanographie dynamique et de climatologie ocean general circulation model ogcm at global scales the forcing fields are provided by the european centre for medium range weather forecasts reanalysis project the ogcm is a coarse horizontal resolution model 2 longitude by 1 5 latitude with 31 levels in the vertical mainly used for climate studies horizontal mixing is done along isopycnal surfaces whereas the parameterization of vertical mixing is based on a local estimate of the turbulent kinetic energy the comparison is quantitative in the sense that topex poseidon observations are interpolated onto the model grid by an objective interpolation in view of the assimilation case the model simulation is compared to the observations at large spatial scales of 500 km or more the basic features of the variability are simulated well by the model in particular with respect to the annual cycle major discrepancies are found in the vicinity of western boundary currents and in the southern ocean due in part to the inadequate horizontal resolution in anticipation of a future assimilation of the observed sea level a decomposition of the model sea level into baroclinic barotropic components diagnosed with some dynamical variables of the model is then examined it is shown that the baroclinic component explains the large seasonal variations confined in the upper layers whereas the barotropic component is associated with intraseasonal variability the results of the present study confirm that the model sea level is consistent with the observed large scale variability providing a basis for future assimilation of the data into the ogcm to improve the representation of the ocean state

measuring gravity field variability the geoid ocean bottom pressure fluctuations and their dynamical implications 1 to obtain insight into bottom pressure variability and requirements for assimilating gravity data into an ocean general circulation model we use recent results from a constrained global model bottom pressure variability as contrasted to surface elevation variability is examined at the annual semiannual chandler wobble and 4 month periods surface elevation and bottom pressure variability occurs on all spatial and temporal scales resolvable by our analysis and patterns can be quite different a barotropic index developed to quantify variability character suggests the importance of steric effects at longer periods variability decomposition into standing eastward and westward traveling waves indicates a strong zonal component for both surface elevation and bottom pressure with bottom pressure showing a greater overall tendency toward eastward propagation and surface elevation showing a greater overall tendency toward westward propagation bottom pressure variability signals are estimated to be recoverable from space to spherical harmonic degree 27 for the annual cycle and 14 for the semiannual and chandler wobble cycles mass exchange arising from model approximations is detectable to about degree 7 polar motion excitation by ocean seafloor loading is found to be quantitatively important spurious oscillations encountered in using spherical harmonics to represent oceanic fields are suppressed using lanczos factors

high resolution records of late holocene climate change and carbon accumulation in two north west european ombrotrophic peat bogs the peat stratigraphy plant macrofossils colorimetric humification pollen non pollen microfossils carbon nitrogen ratios of three replicate cores from a raised peat bog in the uk walton moss and a single core from a raised peat bog in denmark lille vildmose were examined in an attempt to investigate the relation between long term climate change and changes in species composition of the peat forming vegetation nine wet shifts identified in the monoliths from walton moss and lille vildmose mainly occurred during periods of increasing atmospheric c 14 content because fluctuations in holocene atmospheric radiocarbon concentrations have been shown to be due to variations in solar activity the little ice age lia climatic deteriorations registered in both peat bogs were probably driven by changes in solar activity climatic deteriorations in the three replicate cores from walton moss are not all consistently registered and may reflect the internal variability in the extent of hollow lawn hummock microforms within raised peat bog ecosystems the lowest carbon accumulation values for the walton moss monoliths between ca cal ad 1300 and 1800 and between ca cal ad 1490 and 1580 for lille vildmose occurred during the course of lia climatic deteriorations peat bog primary productivity may have been reduced during the lia owing to lower spring summer temperatures and shorter growing seasons for the peat forming plants species specific higher decomposition rates may have also caused the lower carbon accumulation rates in the peat bogs during the lia c 2002 elsevier science b v all rights reserved

vegetation history and environmental development since ca 6000 cal yr bp in and around ispani 2 kolkheti lowlands georgia abstract the kolkheti lowlands of western georgia have a unique vegetation and a rich cultural history palynological and macrofossil analysis accompanied by ams 14c dates of the deposits of the ispani 2 mire near kobuleti allow the reconstruction of regional vegetation environmental history and local peatland development within the context of black sea level and cultural changes comparison of two adjacent peatland cores confirms spatial differences in wetland development prior to 5400 cal yr bp the ispani basin was a floodplain of an active river system where overbank deposits with fluvially transported castanea pollen were deposited subsequently a lake or lagoon developed in which reeds expanded these were succeeded by herb rich open alder carrs after 1900 cal yr bp carpinus and fagus expanded on the dry grounds where formerly quercus was more abundant also castanea declined local reedbeds that burned regularly succeeded the alder carr after 1000 cal yr bp a percolation bog developed resulting in the formation of 4 m of loose porous and largely undecomposed sphagnum austinii peat with molinia roots the upper 50 cm of the analysed section show extensive human impact on the landscape during the 20th century

a sensitive high resolution record of late holocene climatic change from a raised bog in northern england proxy climatic data in the form of plant macrofossils have been analysed from a 5 m core from bolton fell moss cumbria uk detailed analysis of peat from the upper 50 cm of this core is used to demonstrate a strong correlation between changes in the relative proportion of taxa and known climatic changes over the last 1000 years the record of changes in bog vegetation contained within the peat profile is used to reconstruct changes in bog surface wetness for the latter half of the holocene as bog surface wetness is directly controlled by the prevailing climatic conditions this reconstruction can be viewed as a proxy climate record twelve radiocarbon age estimates on the 5m core suggest that between 50 and 500 cm peat accumulated at a relatively constant rate of 12 4 yr cm 1 the regular sampling intervals thus provide a time series of past bog surface wetness spectral analyses of this series indicates that wetness changes are cyclic with a ca 800 year periodicity

replicability and variability of the recent macrofossil and proxy climate record from raised bogs field stratigraphy and macrofossil data from bolton fell moss and walton moss cumbria england replication of results is a basic tenet of science but in palaeoecology this is very time consuming and the signal is subject to noise the derivation of proxy climate signals from ombrotrophic peat was carried out originally using samples from open peat faces where the stratigraphic relationships could be easily observed now that such sections are rare and often degraded there is a need to demonstrate that data can be replicated from core profiles ten short cores taken from two adjacent bogs have been analysed for macrofossils and show a coherent series of changes which are also similar to previous profiles from the same sites it is concluded that variation between profiles is slight and less than observations of present vegetation mosaics might suggest recommendations for a standard approach to fieldwork on raised bogs that emphasises the utility of subfossil pool layers are proposed and the need for a secure chronology is stressed 1998 john wiley sons ltd

a preliminary tidal analysis of topex poseidon altimetry approximately 12 months of data from the topex poseidon satellite altimeter mission are analyzed for the major short period oceanic tides a harmonic analysis is performed on data captured within bins defined on a deep ocean grid which owing to tidal aliasing considerations must have a relatively coarse spatial resolution our analysis is in terms of corrections to the schwiderski and cartwright ray models and it confirms many of the schwiderski differences previously reported by cartwright and ray our differences with respect to the geosat based cartwright and ray model form a sectorial pattern in m2 with high low differences separated roughly 180 in longitude we suggest that these sectorial errors were most likely induced by geosat s relatively large orbit error comparisons to independent data validate the improved topex poseidon solutions in situ ground truth shows m2 rms differences of 4 10cm schwiderski 3 86cm cartwright and ray 2 63cm this paper global rates of energy dissipation confirm earlier estimates for m2 and show improved agreement with satellite tracking studies for k1 and s2 these preliminary exercises confirm that topex poseidon should result in a new generation of improved global tidal models

satellite altimetry the marine geoid and the oceanic general circulation for technical reasons the general circulation of the ocean has historically been treated as a steady laminar flow field the recent availability of extremely highaccuracy and high precision satellite altimetry has provided a graphic demonstration that the ocean is actually a rapidly time evolving turbulent flow field to render the observations quantitatively useful for oceanographic purposes has required order of magnitude improvements in a number of fields including orbit dynamics gravity field estimation and atmospheric variability with five years of very high quality data now available the nature of oceanic variability on all space and time scales is emerging including new findings about such diverse and important phenomena as mixing coefficients the frequency wavenumber spectrum and turbulent cascades because the surface elevation is both a cause and consequence of motions deep within the water column oceanographers soon will be able to provide general circulation numerical models tested against and then combined with the altimeter data these will be complete three dimensional timeevolving estimates of the ocean circulation permitting greatly improved estimates of oceanic heat carbon and other property fluxes

large scale variability in the midlatitude subtropical and subpolar north pacific ocean observations and causes abstract altimetric data from the 8 yr topex poseidon t p mission oct 1992 jul 2000 are used to investigate large scale circulation changes in the three current systems of the midlatitude north pacific ocean the north pacific current npc the alaska gyre and the western subarctic gyre wsg to facilitate the understanding of the observed changes a two layer ocean model was adopted that includes first mode baroclinic rossby wave dynamics and barotropic sverdrup dynamics the npc intensified steadily over the t p period from 1992 to 1998 much of this intensification is due to the persistent sea surface height ssh drop on the northern side of the npc a similar ssh trend is also found in the interior of the alaska gyre both of these ssh changes are shown to be the result of surface wind stress curl forcing accumulated along the baroclinic rossby wave characteristics initiated from the eastern boundary in addition to the interior ssh signals the intensity of the alaska gyre is shown to depend

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

estimates from altimeter data of barotropic rossby waves in the northwestern atlantic ocean abstract a dynamical model representing linear barotropic rossby waves is combined with geosat data from the northwest atlantic ocean the model is too simple to be very realistic in this complex area but the problem of combining any model with real data raises a number of issues that we address the combination method used is sequential estimation in the form of a filtering smoothing operation a fraction of the total signal variance 5 to 15 in the area over several spacecraft repeat cycles is demonstrated to be consistent with five rossby waves that the result is robust is demonstrated by recovering known signals added synthetically to the real data

multiproxy late holocene peat records from ireland towards a regional palaeoclimate curve two new peat based climate records from ireland covering the late holocene are presented the sequences are dated by a strong chronological framework formed by ams radiocarbon dates and scps three proxy indicators testate amoebae macrofossils and humification have been determined allowing the limitations and strengths of each to be identified and utilised to provide a bog surface wetness bsw record for both sites age depth models take into account the potential for accumulation rates to vary with bog vegetation the records from each site have been used to derive a combined bsw record that displays changes to a wetter cooler climate from ca ad 30 1920 bp ca ad 310 1640 bp ca ad 805 1145 bp ca ad 1040 910 bp and ca ad 1300 650 bp changes follow closely those identified in a northern britain composite bsw record and largely correspond with lake level data in central france suggesting the main changes in water balance were coherent over a large region correspondence with increases in ird and slower iceland scotland overflow water isow suggests that these changes were related to oceanic forcing influencing the track of dominant westerly air flow over ireland copyright 2007 john wiley sons ltd

the disappearance of sphagnum imbricatum from butterburn flow uk the disappearance of the previously abundant moss species sphagnum imbricatum has been investigated at butterburn flow northern england using organic geochemical elemental macrofossil pollen and testate amoebae analyses variations in the assemblage of peat forming plants were tracked using the macrofossil distributions as well as the relative chain lengths of n alkanes and concentrations of 5 n alkylresorcinols and triterpenols no significant changes to the vegetation assemblage could be detected prior to the loss of s imbricatum variations in water depth were reconstructed using a testate amoebae transfer function and inferred qualitatively using bulk elemental composition and biomarkers for changing redox conditions in the bog subsurface the degree of isomerization in the c31 hopanes and the concentrations of bishomohopanol and archaeol pollen analysis reconstructed the landscape surrounding the mire and revealed evidence for human disturbance the results suggest that bog surface wetness increased with the transition from sphagnum imbricatum to sphagnum magellanicum but the increase was not large and s imbricatum had previously survived similar periods of wetness however the loss of s imbricatum coincides with increasing human disturbance surrounding the bog which may have altered nutrient inputs to the bog surface from agriculturally derived dust to the detriment of s imbricatum but to the benefit of s magellanicum and eriophorum vaginatum it is proposed here that the stresses imposed by the combination of changing nutrient inputs and a rapidly rising water table drove the disappearance of s imbricatum from butterburn flow at c cal ad 1300

wind influence on the mesoscale activity along the gulf stream and the north atlantic currents two independent data sets are used to diagnose the wind effect on the mesoscale activity in the north atlantic ocean the oceanic surface variability is described with topex poseidon sea surface height measurements from october 1992 to september 1997 spatial extensions and temporal variations of high mesoscale activity are compared with the zonal and meridional components of the ers 1 wind stress the ekman pumping and the zonal sverdrupian velocity regions with high mesoscale surface variability seem to be correlated to regions with eastward sverdrupian velocities when the sverdrupian velocity is eastward and increases with time the mesoscale activity is intensified indicating a growth of instability rates theoretical and numerical results based on the interplay of barotropic eastward sverdrup flows and westward propagation of long rossby waves suggest that the wind controls western regions where baroclinic instability is favored interactions between the eddy field and the mean circulation are therefore analyzed to try to extract the instability mechanism responsible for the growth of the mesoscale activity along the gulf stream and the north atlantic current our results seem to suggest that the seasonal changes of mesoscale activity associated with eastward currents are linked to seasonal changes of the eastward sverdrupian velocity

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

observing ocean heat content using satellite gravity and altimetry 1 a method for combining satellite altimetry observations with satellite measurements of the earth s time varying gravity to give improved estimates of the ocean s heat storage is presented over the ocean the time variable component of the geoid can be related to the time varying bottom pressure the methodology of estimating the ocean s time varying heat storage using altimetric observations alone is modified to include observations of bottom pressure a detailed error analysis of the methodology is undertaken it is found that the inclusion of bottom pressure improves the ocean heat storage estimates the improvement comes from a better estimation of the steric sea surface height by the inclusion of bottom pressure in the calculation over using the altimeter observed sea surface height alone on timescales of the annual cycle and shorter the method works particularly well however long timescale changes in the heat storage are poorly reproduced because of deficiencies in the methodology and the presence of contaminating signals in the bottom pressure observations index terms 4556 oceanography physical sea level variations 1223 geodesy and gravity ocean earth atmosphere interactions 3339 1227 geodesy and gravity planetary geodesy and gravity 5420 5714 6019 1243 geodesy and gravity space geodetic surveys 4275 oceanography general remote sensing and electromagnetic processes 0689 keywords ocean heat content altimetry satellite gravity steric height remote sensing

a 9000 year record of cyclic vegetation changes identified in a montane peatland deposit located in the eastern carpathians central eastern europe autogenic succession or regional climatic influences abstract we present a high resolution continuous plant macrofossil remains record complemented by a pollen sequence from t ul muced bog in the eastern carpathian mountains romania the record spans the last 9000 years and we test whether peatland development in the eastern carpathians is linked to climate change or to autogenic succession we find that sphagnum magellanicum was the dominant peat forming species for ca 8000 years but we also identify ten phases of increased representation of eriophorum vaginatum at approximately 8100 7550 6850 6650 5900 4650 3150 1950 1450 and 750 cal yr bp visual inspection and wavelet analysis show that the episodic increases in the relative abundances of eriophorum vaginatum were simultaneous with decreased abundances of sphagnum magellanicum and sphagnum angustifolium comparison with published palaeoclimatic records in this region suggests that these cyclical successions of s magellanicum and e vaginatum appear to be primarily a result of climate changes with e vaginatum developing mainly during dry phases and s magellanicum during wetter periods we therefore suggest that the development of this peatland was largely influenced by changing climatic conditions although the role of autogenic plant succession cannot be excluded our results show the value of ombrotrophic peat deposits as archives of past climate change

deep variability in the atlantic western boundary current based on altimetric and expendable bathythermograph data 1 the deep variability in two areas of the atlantic western boundary is studied one site is located at 38 n inshore of the gulf stream the other is at 8 s off the brazilian coast analyses are centered on current time series estimated by a method that uses expendable bathythermograph derived dynamic heights to remove the near surface signal from altimetric sea surface height both series are approximately 6 years long currents are compared to scatterometer derived alongshore wind stress and basin wide wind stress curl in both areas current variability is correlated to basin averaged wind stress curl and also to alongshore wind stress the relationship between currents and wind curl is coherent with the western boundary currents response to interior sverdrup flow we propose that alongshore wind stress exerts control over the flow by divergence of the ekman flow at the coast in the north the variability is dominated by interannual oscillations of the wind curl the effects of the alongshore stress are secondary and have annual frequency in the southern site the alongshore effect appears to be the dominant forcing the main observed results are confirmed by data from a numerical model with 1 6 horizontal resolution

proxy climate record for the last 1000 years from irish blanket peat and a possible link to solar variability recent research has shown that ombrotrophic mires can yield a proxy climate signal based on changes in the degree of peat humification 1 2 and that oceanic margin sites show the most sensitive record 3 we compare humification records for the last 1000 yr from two radiocarbon dated blanket peat profiles from western ireland and show several corresponding periods of climatic fluctuations periods favouring reduced peat decomposition suggestive of wetter and or cooler climatic conditions seem to coincide with periods of reduced sunspot activity and atmospheric14c anomalies whilst climatologists have continued to debate a link between solar variability on a century timescale and climate change the exact nature of that link remains elusive 4 7 the results from ireland demonstrate that data derived from mires could be relevant to the debate as to the extent of solar forcing in natural climatic variability and the curves shown provide a continuous record to add to previous evidence for the so called medieval optimum and little ice age 8 the record may imply that during the past millennium climatic change at the oceanic margin of the northeast atlantic largely corresponded to inferred variations in solar output

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

the temperature of europe during the holocene reconstructed from pollen data we present the first area average time series reconstructions of warmest month coldest month and mean annual surface air temperatures across europe during the last 12 000 years these series are based on quantitative pollen climate reconstructions from over 500 pollen sites assimilated using an innovative four dimensional gridding procedure this approach combines three dimensional spatial gridding with a fourth dimension represented by time allowing data from irregular time series to be focussed onto a regular time step we provide six regional reconstructed temperature time series as well as summary time series for the whole of europe the results suggest major spatial and seasonal differences in holocene temperature trends within a remarkably balanced regional and annual energy budget the traditional mid holocene thermal maximum is observed only over northern europe and principally during the summer this warming was balanced by a mid holocene cooling over southern europe whilst central europe occupied an intermediary position changes in annual mean temperatures for europe as a whole suggest an almost linear increase in thermal budget up to 7800 bp followed by stable conditions for the remainder of the holocene this early holocene warming and later equilibrium has been mainly modulated by increasing winter temperatures in the west which have continued to rise at a progressively decreasing rate up to the present day

maceral composition and molecular markers of two condensed middle holocene peat profiles in n spain abstract this study deals with the palaeohydrological information obtained from lipids composition and vegetal tissue preservation of two peat cores from asturias north spain the two profiles differ in the type of peatland raised bog in la borbolla and blanket bog in buelna and the type of organic matter being more bryophytic in the raised bog and more herbaceous in the blanket bog the peatlands are located close to the coast on impermeable old flat erosion surfaces which favoured peat accumulation within a distance of 3 5 km from each other the accumulation rate varied between 0 05 and 0 07 mm yr and the records extend from around 9000 to 2500 cal yr bp the main differences between the two peat sites can be summarized as follows the raised bog has lower mineral matter content and h c atomic ratio and higher c n ratio and extraction yields compared to the blanket bog it has also a higher tissue preservation index for huminite macerals and increasing inertodetrinite index with depth regarding biomarkers the raised bog has a relatively higher concentration of n alkane 2 ones compared to the corresponding n alkane of similar carbon number higher concentration of medium vs high molecular weight methyl ketones and higher triterpenoids steroids ratio than the blanket bog alternating humid dry periods have been recorded in both profiles based on lipid concentrations indicating that the sphagnum rich intervals in the raised bog are more sensitive than the herbaceous blanket peat record to climatic variations the main humid intervals identified are dated as 5000 7500 cal yr bp in the blanket bog and as 6000 3500 cal yr bp and last 2500 cal yr bp in the raised bog and correlate with the humid periods traced in other peatlands locations in this region the transition middle to late holocene is characterized by humid conditions in the region which favoured the sphagnum growth in the peats the reflectance of huminite in these records appears to be more related with differences in the oxidative conditions than with variation of peat maturity it is higher in the layers with high mineral matter content at the beginning of organic matter accumulation and also in the upper part of the profile subjected to seasonal desiccation a more intense biochemical gelification coincides with higher concentration of hopanoids derived from bacteria in the upper part of the profile acrotelm high amount of nonadecan 2 one k 19 and high concentrations of triterpenyl acetates which are also determined in other peat profiles from northern spain are also detected in these profiles this indicates that the specific conditions required for the formation of these compounds probably associated to wet temperate climate dominated throughout the region

wind forced variability of the deep eastern north pacific observations of seafloor pressure and abyssal currents data from an array of bottom pressure gauges and a string of current meters in the vicinity of 47on 139ow are used to examine the deep ocean variability forced by ocean surface wind stress curl from august 1987 to june 1988 bottom geostrophic currents are computed from the pressure gauge array and these correspond well to the long period directly measured currents at 3000 m the supratidalperiod bottom pressure variations are coherent at 95 confidence with the wind stress curl in period bands of 3 4 days and 15 60 days but removed in distances of 400 and 700 km to the northwest and the southeast respectively a linear two layer hydrodynamic model is used to examine the theoretical forcing produced by random phased surface wind fields for the conditions of the eastern north pacific and the 15 to 60 day period observed response is reproduced credibly to model 3 to 15 day variations more realistic models are required currents are related to surface winds were derived from yearlong current meter records in a cluster of moorings north and east of barbados koblinsky and niiler 1982 showed that significant coherences existed between the 4 to 40 dayperiod east west pulsations of the trade winds r x above barbados and the north south currents v at all depths in the ocean at 15on 54ow the response amplitude of v to r x was depth and period dependent it decreased by a factor of 3 from 150 to 4000 m depths and increased by a factor of 5 from 8 to 40 day periods the interpretation of these data was that the deep ocean forcing was produced by large horizontal scale wind stress curl hereinafter referred to simply as curl due to westward propagating pulses in the trade winds with larger east west than north south scale the amplitude of the deep wind related currents was 1 3 cm s thus deep ocean forcing should be observable in many places where the mesoscale eddy energy is low theoretically wind forced deep ocean motions should depend upon wind stress curl mt iller and frankignoul 1981 using a model of randomly forced linear motions in a stratified infinite flat bottom beta plane ocean computed local coherences and showed that motions across the planetary vorticity gradient should exhibit the strongest coherence with the local wind stress curl niiler and koblinsky 1985 using current meter data demonstrated that such a dynamical link does in fact exist locally at 42on 152ow although at a shorter period than was predicted by milller and frankignoul both the amplitude and the phase of the currents that were forced across the planetary potential vorticity field orf h contours on a 150 km horizontal scale were predicted from the local surface wind stress computed from a similar 150 km scale wind field the 4000 m oscilla

holocene climate variability revealed by oxygen isotope analysis of sphagnum cellulose from walton moss northern england abstract stable isotope analyses of sphagnum alpha cellulose precipitation and bog water from three sites across northwestern europe raheenmore ireland walton moss northern england and dosenmoor northern germany over a total period of 26 months were used to investigate the nature of the climatic signal recorded by sphagnum moss the 18o values of modern alpha cellulose tracked precipitation more closely than bog water with a mean isotopic fractionation factor cellulose precipitation of 1 0274 0 001 1 27 sub samples of isolated sphagnum alpha cellulose were subsequently analysed from core wlm22 walton moss northern england yielding a sphagnum specific isotope record spanning the last 4300 years the palaeo record calibrated using the modern data provides evidence for large amplitude variations in the estimated oxygen isotope composition of precipitation during the mid to late holocene estimates of palaeotemperature change derived from statistical relationships between modern surface air temperatures and 18oprecipitation values for the british isles give unrealistically large variation in comparison to proxies from other archives we conclude that use of such relationships to calibrate mid latitude palaeo data must be undertaken with caution the 18o record from sphagnum cellulose was highly correlated with a palaeoecologically derived index of bog surface wetness bsw suggesting a common climatic driver

molecular and isotopic stratigraphy in an ombrotrophic mire for paleoclimate reconstruction a 40 cm deep sphagnum dominated peat monolith from bolton fell moss in northern england was systematically investigated by lipid molecular stratigraphy and compound specific 13c and d analysis using gas chromatography gc gc mass spectrometry gc ms gc combustion isotope ratio ms gc c irms and gc thermal conversion irms gc tc irms techniques 210pb dating showed the monolith accumulated during the last ca 220 yr a period encompassing the second part of little ice age while the distributions of lipids including n alkan 1 ols n alkan 2 ones wax esters sterols n alkanoic acids alkandioic acids and hydroxy acids display relatively minor changes with depth the cooler climate event was recorded in the concentrations of n alkanes and organic carbon cpi values of n alkanes and n alkanoic acids and the ratio of 5 n alkylresorcinols sterols superimposed on the fossil fuel effect the relatively cooler climate event was also recorded by 13c values of individual hydrocarbons especially the c23n alkane a major compound in certain sphagnum spp the d values of the c29 and c33n alkanes correlated mainly with plant composition and were relatively insensitive to climatic change in contrast the c23n alkane displayed variation that correlated strongly with recorded temperature for the period represented by the monolith agreeing with previously reported deuterium records in tree ring cellulose spanning the same period in scotland germany and the usa with more negative values occurring during the second part of little ice age these biomarker characteristics including the compound specific 13c and d records provide a new set of proxies of climatic change potentially independent of preserved macrofossils which will be of value in deeper sections of the bog where the documentary records of climate are unavailable and humification is well advanced

evidence for climatic deteriorations associated with the decline of sphagnum imbricatum hornsch ex russ in six ombrotrophic mires from northern england and the scottish borders the decline of sphagnum imbricatum from the peat stratigraphy of six ombrotrophic mires bolton fell moss and walton moss raeburn flow and bell s flow and coom rigg moss and felecia moss has been investigated using colorimetric humification quantitative plant macrofossil and testate amoebae analyses the chronology of each peat profile was determined by radiocarbon assay and pollen land use correlations palaeoclimate reconstructions have been made by linking known documentary historical changes in climate and other proxy climate records to those inferred from the sites investigated in the study region in two of the ombrotrophic mires examined there are wet shifts associated with the decline and local extinction of s imbricatum which are dated to cal ad 1160 1400 raeburn flow and bell s flow in coom rigg moss and felecia moss wet shifts are also associated with the decline and local extinction of s imbricatum between cal ad 1395 1485 the decline of s imbricatum from two other ombrotro

oceanic tides from geosat altimetry direct tidal analysis of the altimetry from the geosat exact repeat mission s first year is used to derive estimates of the diurnal and semidiurnal oceanic tides the geoid is removed by collinear differences at 34 1 day separation and the orbit error is reduced by subtracting a slowly modulated 1 cycle revolution term a sequence of independent analyses at grid areas of 1 latitude 1 5 longitude using orthotide functions ensures complete definition of the diurnal and semidiurnal species global admittance maps for m2 and s2 within the latitudes 58 n and 59 s compare well with ground truth at 66 open ocean sites maps of differences between geosat and the naval surface weapons center model show important areas of the order of 10 15 cm the integral for the global power input from the moon gives 2 51 tw m2 0 44 tw s2 lower than many previous estimates but in agreement with figures deduced from a recent analysis of satellite orbits

evidence for wind driven current fluctuations in the western north atlantic two subsurface current meter moorings were deployed for 20 months along 70 w in a low energy portion of the western north atlantic the resulting data were compared with estimates of the wind stress curl in an attempt to seek a relationship between currents below the mixed layer and meteorological forcing at subinertial frequencies currents and temperature tend to be significantly coherent with the curl and are most coherent with the curl at remote locations usually more than 500 km away from the mooring and generally to the east coherences generally decrease with increasing frequency the current response is surface intensified a linear stratified model for stochastically wind forced rossby waves in a flat bottomed ocean is presented as an attempt to rationalize the results the effort was not entirely successful so that it appears that a more realistic model perhaps including bottom topography and mean currents will be needed to rationalize these observations fully

wind forced intraseasonal sea level variability of the extratropical oceans abstract seven years worth of sea level observations from the topex poseidon altimeters and wind observations from the european remote sensing satellites ers 1 2 scatterometers were used to investigate the dynamics of large scale intraseasonal sea level variability at mid and high latitudes coherent patterns of sea level variability with spatial scales of 1000 km and timescales of 20 days to 1 year are identified in three particular regions the bellingshausen basin west of drake passage the australian antarctic basin and the central north pacific ocean 30 50 n near the date line significant coherence is found between wind stress curl and the sea level variability a simple barotropic vorticity equation in which the time rate of relative vorticity variation is balanced by the wind stress curl and a damping term is used to simulate the sea level anomalies with a significant degree of correlation with the observations although the coherence between the simulation and the observation is signifi

role of winds in estimation of ocean heat storage anomaly using satellite data 1 the heat storage anomaly of the upper ocean can be estimated using altimeter data based on the thermal dynamics equation in this study we analyzed both nonthermal and thermal steric height measured by altimetry and removed nonthermal steric height from altimeter measurements to calculate the heat storage anomaly from thermal steric height alone in the global oceans but with a focus on the pacific ocean after examining nonthermal steric height salinity waves and wind we believe that wind stress is a major component to the change in sea surface height blended topex poseidon and ers 1 2 altimeter 1 1 sea surface height anomaly from january 1993 to october 2000 were used to calculation of the heat storage anomaly in addition we used expendable bathythermograph xbt data to the global oceans to determine a reference heat storage from which the altimeter estimation of the heat storage was compared the wind stress curls from scatterometer data obtained from january 1993 to october 2000 were used for analyzing the wind effects on sea surface height variation the correlation coefficients between heat storage from altimeter data halt and that from the xbt hxbt are larger than 0 6 in the global oceans except in the regions of 20 n in the eastern pacific the eastern tropical pacific the tropical atlantic and the western tropical indian ocean the root mean square rms of the differences halt hxbt has large values in the gulf stream and the kuroshio extension regions as well as the eastern and western tropical pacific and eastern indian ocean the wind induced sea surface height variation exhibits strong annual and interannual cycles so the empirical orthogonal function eof method was employed to extract the cycles the annual cycle has two modes whereas the interannual cycle is characterized by el nino events wind stress can affect the estimation of the heat storage through mechanisms derived from quasi geostrophic and barotropic theory we calculated the correlation coefficient between the differences halt hxbt and wind stress curl the result shows that el nino southern oscillation enso related wind stress curl anomalies are responsible for estimating discrepancy in the regions west of south and north america and tropical oceans the high correlation suggests that in these regions the barotropic and linear theory is the dynamic mechanism underlying the wind effects on heat storage estimation furthermore we focus on baroclinic signal in sea level resulting from ekman upwelling in the tropical oceans the effect of wind forcing has the most important role in sea level change during the 1997 1998 el nino event for instance the heat storage anomaly q due to the strong coastal upwelling off the west coast of peru closely relates to sea surface temperature sst wind forcing remnant sea level height anomaly after removing the contributions of the heat salt and waves to the sea level height and ekman depth dek however the q in the west coast of america and western pacific warm pool areas did not closely relate to sst wind forcing and dek

a multiproxy climate record from a raised bog in county fermanagh northern ireland a critical examination of the link between bog surface wetness and solar variability a proxy climate record from a raised bog in county fermanagh northern ireland is presented the record spans the interval between 2850 cal yr bc and cal yr ad 1000 and chronological control is achieved through the use of tephrochronology and 14c dating including a wiggle match on one section of the record palaeoclimatic inferences are based on a combination of a testate amoebae derived water table reconstruction peat humification and plant macrofossil analyses this multiproxy approach enables proxy specific effects to be identified major wet shifts are registered in the proxies at ca 1510 cal yr bc 750 cal yr bc and cal yr ad 470 smaller magnitude shifts to wetter conditions are also recorded at ca 380 cal yr bc 150 cal yr bc cal yr ad 180 and cal yr ad 690 it is hypothesised that the wet shifts are not merely local events as they appear to be linked to wider climate deteriorations in northwest europe harmonic analysis of the proxies illustrates statistically significant periodicities of 580 423 373 307 and 265 years that may be related to wider holocene climate cycles this paper illustrates how the timing of climate changes registered in peat profiles records can be precisely constrained using tephrochronology to examine possible climatic responses to solar forcing relying on interpolated chronologies with considerable dating uncertainty must be avoided if the climatic responses to forcing mechanisms are to be fully understood copyright 2007 john wiley sons ltd

causes of large scale sea level variations in the southern ocean analyses of sea level and a barotropic model 1 we analyze a decade of sea surface height ssh measurements in the southern ocean from the topex poseidon and ers altimeters with a focus on the variability at timescales 2 years among the different processes contributing to large scale ssh variations the barotropic response to the winds dominates poleward of 50 s while thermosteric processes dominate equatorward except for resonant basins for the barotropic modes and regions of intense eddy activity a finite element barotropic model has been developed to analyze the vorticity budget the ssh from the model agrees well with observations the leading barotropic mode which is annular and is confined near antarctica is responsible for most of the barotropic circumpolar transport it is coherent with the zonally integrated eastward wind stress consistent with a free mode response although previously evidenced in bottom pressure data this mode is only partially seen in altimeter data because of ice coverage it nevertheless distinctly appears above the pacific ridges where it expands meridionally up to midlatitudes in the rest of the domain several regions coherent with the local wind stress curl are found these are regions isolated by f h contours mostly deep basins an analysis of the vorticity budget shows that generally topographic sverdrup balance is the leading process for periods 50 days but in some regions resonant basins diffusive and nonstationary terms are important a model experiment shows that transients redistribute energy along f h waveguides contributing to drain resonant regions as was hypothesized in previous works

a 7500 year peat based palaeoclimatic reconstruction and evidence for an 1100 year cyclicity in bog surface wetness from temple hill moss pentland hills southeast scotland analyses of plant macrofossils peat humification and testate amoebae were used to reconstruct a proxy climate record spanning the last 7500 years from an ombrotrophic bog temple hill moss in southeast scotland the plant macrofossil data were subjected to detrended correspondence analysis dca which modelled effectively the significant wet shifts within the record a mean water table depth transfer function was applied to the testate amoebae data to provide quantifiable changes the three proxy records show coherent phase changes which are interpreted as variability in past effective precipitation two tephra horizons glen garry and lairg a were used in conjunction with radiocarbon dates to construct an age depth model producing a robust geochronology from which a time series was calculated the palaeoclimatic reconstruction identified major wet shifts throughout the holocene with specific events occurring around cal 6650 5850 5300 4500 3850 3400 2800 2450 1450 1350 and 250 150 bp spectral analysis of the plant macrofossil dca and colorimetric humification data produced a millennial scale periodicity of 1100 years the same periodicity has also been found in a palaeoclimatic reconstruction from a site in cumbria walton moss and may be linked with millennial scale periodicities found in oceanic palaeoclimatic records

seasonal variation in the in and outflow of the okhotsk sea with the north pacific abstract this paper examines the seasonal variation in the in and outflow of the okhotsk sea with the pacific mainly based on profiling float and satellite altimeter data the motions of the floats at depths of 500 750 m show that the waters of the okhotsk tend to flow out to the pacific through the southern kuril straits mostly bussol strait in winter seasons november march based on data from the floats exiting the sea the mean residence time of the intermediate water in the kuril basin is estimated as about one year isopycnal analysis from the profiling data shows that in the mid eastern area of the okhotsk sea potential temperature of the intermediate water with 26 6 27 2 increases by 0 2 0 5 c in every spring suggesting the inflow from the pacific in the preceding season these suggest that the in and outflow predominantly occurs during winter with the inflow at the northern straits and outflow at the southern straits the surface current field inferred from satellite altimeter data also shows that the inflow to the sea of okhotsk through the northern straits is strengthened in winter linked with strengthening of the east kamchatka current ekc from yearly anomalies of the altimeter data the winter inflow to the okhotsk through the northern straits is significantly correlated with the ekc and sverdrup transport over the north pacific further interannual variations in property of okhotsk sea intermediate water appear to be related with the ekc and wind stress over the north pacific in winter possibly through the change in inflowing pacific water transport these suggest that the seasonal and interannual variations of the in and outflow are to some extent controlled by the large scale wind stress over the north pacific being consistent with island rule qualitatively