proposed re dating of the european ice core chronology by seven years prior to the 7th century ad 1 progress in the study of past climate change requires integration of historical documentation tree ring data and ice core chemistry larsen et al 2008 re evaluate volcanic acid signals in the dye 3 grip and ngrip ice cores and identify large eruptions at 529 2 and 533 534 2 the latter claimed to cause the dry fog of 536 537 and environmental consequences to 550 this conflicts with previous suggestions of a two stage environmental event one in 536 the second c 540 understanding the full range of natural hazards requires critical evaluation of the happenings in the mid 6th century this paper will show that 4 spaced tree ring responses to extreme environmental conditions in the 6th century can be used to re locate 4 key ice acid dates moving the ice core chronology forward 7 years places two large volcanoes in 536 and 541 explaining the extended duration of the 536 550 effects and anchoring the ice chronology

revised calendar date for the taupo eruption derived by 14c wiggle matching using a new zealand kauri 14c calibration data set taupo volcano in central north island new zealand is the most frequently active and productive rhyolite volcano on earth its latest explosive activity about 1800 years ago generated the spectacu

a detailed 2840 year record of explosive volcanism in a shallow ice core from dome a east antarctica a detailed history of volcanism covering the last 2840 years is reconstructed from the top 100 42 m of a 109 91 m ice core from dome a da2005 ice core east antarctica using two known volcanic stratigraphic markers the mean accumulation rate during the period ad 1260 1964 is found to be 23 2 mm w e a 1 consistent with the previously reported accumulation rate at dome a this mean accumulation rate is used to date the entire core volcanic eruptions in the period 840 bc ad 1998 are detected as outstanding sulphate events seventy eight eruptions are identified with a mean of 2 7 eruptions per century comparisons with previous antarctic ice core volcanic records are made to assess the quality of this new da2005 record in terms of dates for volcanic events the da2005 record is in good agreement with previous records in the second millennium ad ad 1000 1998 a series of volcanic signatures found in both the da2005 record and several other antarctic ice core records in the first millennium ad ad 1 1000 appear to validate the da2005 record during this time period for the older periods direct comparisons are difficult between the da2005 record and other antarctic ice core records due to the lack of well dated stratigraphic horizons

atmospheric volcanic loading derived from bipolar ice cores accounting for the spatial distribution of volcanic deposition 1 previous studies have used small numbers of ice core records of past volcanism to represent hemispheric or global radiative forcing from volcanic stratospheric aerosols with the largest ever assembly of volcanic ice core records and state of the art climate model simulations of volcanic deposition we now have a unique opportunity to investigate the effects of spatial variations on sulfate deposition and on estimates of atmospheric loading we have combined 44 ice core records 25 from the arctic and 19 from antarctica and goddard institute for space studies modele simulations to study the spatial distribution of volcanic sulfate aerosols in the polar ice sheets we extracted volcanic deposition signals by applying a high pass loess filter to the time series and examining peaks that exceed twice the 31 year running median absolute deviation our results suggest that the distribution of volcanic sulfate aerosol follows the general precipitation pattern in both regions indicating the important role precipitation has played in affecting the deposition pattern of volcanic aerosols we found a similar distribution pattern for sulfate aerosols from the 1783 1784 laki and 1815 tambora eruptions as well as for the total b activity after the 1952 1954 low latitude northern hemisphere and 1961 1962 high latitude northern hemisphere atmospheric nuclear weapon tests this confirms the previous assumption that the transport and deposition of nuclear bomb test debris resemble those of volcanic aerosols we compare three techniques for estimating stratospheric aerosol loading from ice core data radioactive deposition from nuclear bomb tests pinatubo sulfate deposition in eight antarctic ice cores and climate model simulations of volcanic sulfate transport and deposition following the 1783 laki 1815 tambora 1912 katmai and 1991 pinatubo eruptions by applying the above calibration factors to the 44 ice core records we have estimated the stratospheric sulfate aerosol loadings for the largest volcanic eruptions during the last millennium these loadings agree fairly well with estimates based on radiation petrology and model simulations we also estimate the relative magnitude of sulfate deposition compared with the mean for greenland and antarctica for each ice core record which provides a guideline to evaluate the stratospheric volcanic sulfate aerosol loading calculated from a single or a few ice core records

a continuous 770 year record of volcanic activity from east antarctica a 100 m ice core from site g 15 accumulation rate 0 1 m water yr 1 mean annual temperature 38 c on the mizuho plateau dronning maud land east antarctica has been analysed using the dielectric profiling dep technique the capacitance and conductance of the core were measured at ac frequencies 20 hz 300 khz the high frequency conductivity profile shows variations that are primarily related to the strong acids derived from volcanic activity the tambora 1815 eruption can be identified with the aid of an approximate chronology based on the firn densification rate other historic eruptions can then be recognised beyond about 300 years historical observations are very few however if a constant overall accumulation rate is assumed a well known eruption of 1259 a d can be found near the bottom of the core other peaks in the conductivity profile can then be assigned dates accurate to within a few years using the conductivity profile it is possible to estimate the relative acid deposition fluxes produced by the main eruptions with reasonable accuracy the estimated acid deposisition fluxes realtive to the tambora 1815 eruption of agung 1963 is 27 krakatoa 1883 25 the signal of 1601 28 and that of 1259 53

inter hemispheric transport of volcanic ash from a 1259 a d volcanic eruption to the greenland and antarctic ice sheets a strong volcanic sulfuric acid signal corresponding to an age of 1259 a d has been reported in ice cores from greenland antarctica and arctic canada tiny 5 m volcanic glass shards were reported previously in samples from this layer in an ice core from the south pole here we report the discovery of volcanic glass shards from a contemporaneous layer in an ice core from summit greenland the major element composition of the glass shards in the greenland sample are identical to those from the south pole confirming the assumption that has been made previously that the sulfuric acid signal in the ice cores is an inter hemispheric time stratigraphic marker the composition of these glass shards is similar to those produced by a 550 700 yrs b p eruption of el chichon volcano in mexico suggesting that it may be the source of the widely dispersed material

spatio temporal variability in volcanic sulphate deposition over the past 2 kyr in snow pits and firn cores from amundsenisen antarctica in the framework of the european project for ice coring in antarctica epica a comprehensive glaciological pre site survey has been carried out on amund senisen dronning maud land east antarctica in the past decade within this survey four intermediate depth ice cores and 13 snow pits were analyzed for their ionic compos ition and interpreted with respect to the spatial and temporal variability of volcanic sul phate deposition the comparison of the non sea salt nss sulphate peaks that are related to the well known eruptions of pinatubo and cerro hudson in ad1991 revealed sulphate depositions of comparable size 15 8 3 4 kg km 2 in 11 snow pits there is a tendency to higher annual concentrations for smaller snow accumulation rates the combination of seasonal sodium and annually resolved nss sulphate records allowed the establishment of a time scale derived by annual layer counting over the last 2000 years and thus a detailed chronology of annual volcanic sulphate deposition using a robust outlier detection algo rithm 49 volcanic eruptions were identified between ad165 and 1997 the dating uncer tainty is 3 years between ad1997 and 1601 around 5 years between ad1601 and 1257 and increasing to 24 years at ad165 improving the accuracy of the volcanic chronology during the penultimate millennium considerably abstract in the framework of the european project for ice coring in antarctica epica a comprehensive glaciological pre site survey has been carried out on amund senisen dronning maud land east antarctica in the past decade within this survey four intermediate depth ice cores and 13 snow pits were analyzed for their ionic compos ition and interpreted with respect to the spatial and temporal variability of volcanic sul phate deposition the comparison of the non sea salt nss sulphate peaks that are related to the well known eruptions of pinatubo and cerro hudson in ad1991 revealed sulphate depositions of comparable size 15 8 3 4 kg km 2 in 11 snow pits there is a tendency to higher annual concentrations for smaller snow accumulation rates the combination of seasonal sodium and annually resolved nss sulphate records allowed the establishment of a time scale derived by annual layer counting over the last 2000 years and thus a detailed chronology of annual volcanic sulphate deposition using a robust outlier detection algo rithm 49 volcanic eruptions were identified between ad165 and 1997 the dating uncer tainty is 3 years between ad1997 and 1601 around 5 years between ad1601 and 1257 and increasing to 24 years at ad165 improving the accuracy of the volcanic chronology during the penultimate millennium considerably

volcanic layers in antarctic vostok ice cores source identification and atmospheric implications fifteen visible volcanic ash layers tephra from vostok ice cores have been analyzed for major elements trace elements and sr and nd isotope composition comparison of their geochemical signatures to lava composition from the inventory of antarctic and subantarctic volcanoes which have been active over the last 0 5 million years indicates that nine layers originate from activity of the south sandwich volcanic arc three from southern south america one from the antarctic peninsula bransfield strait and one from west antarctica marie byrd land province the large size of the tephra up to 50 m requires rapid atmospheric transfer from the volcanic centers to east antarctica rapid tropospheric transport from the southwestern atlantic penetrating east antarctica therefore predominates during the period studied whether in glacial or interglacial climatic mode in spite of the low frequency of occurrence of visible tephra layers in vostok core one event every 20 kyr the overall atmospheric pathway of these ash events appears consistent with the almost continuous advection of continental dust from south america

a 220 year continuous record of volcanic h2so4 in the antarctic ice sheet continuous h2so4 profiles observed in snow from several antarctic locations reveal four major volcanic events of the past two centuries agung krakatoa tambora and another large scale event not recorded historically acid deposition and interhemispheric distribution mechanisms are quantified and then used to obtain an order of magnitude estimate for the h2so4 emissions from these eruptions

volcanic sulfate deposition to greenland and antarctica a modeling sensitivity study reconstructions of the atmospheric sulfate aerosol burdens resulting from past volcanic eruptions are based on ice core derived estimates of volcanic sulfate deposition and the assumption that the two quantities are directly proportional we test this assumption within simulations of tropical volcanic stratospheric sulfur injections with the maecham5 ham aerosol climate model an ensemble of 70 simulations is analyzed with so2 injections ranging from 8 5 to 700 tg with eruptions in january and july modeled sulfate deposition flux to antarctica shows excellent spatial correlation with ice core derived estimates for pinatubo and tambora although the comparison suggests the modeled flux to the ice sheets is 4 5 times too large we find that greenland and antarctic deposition efficiencies the ratio of sulfate flux to each ice sheet to the maximum hemispheric stratospheric sulfate aerosol burden vary as a function of the magnitude and season of stratospheric sulfur injection changes in simulated sulfate deposition for large so2 injections are connected to increases in aerosol particle size which impact aerosol sedimentation velocity and radiative properties the latter leading to strong dynamical changes including strengthening of the winter polar vortices which inhibits the transport of stratospheric aerosols to high latitudes the resulting relationship between antarctic and greenland volcanic sulfate deposition is nonlinear for very large eruptions with significantly less sulfate deposition to antarctica than to greenland these model results suggest that variability of deposition efficiency may be an important consideration in the interpretation of ice core sulfate signals for eruptions of tambora magnitude and larger

impact of the cerro hudson and pinatubo volcanic eruptions on the antarctic air and snow chemistry atmospheric records of sulfate and msa in aerosols were obtained by year round samplings in the boundary layer at two coastal antarctic sites neumayer 1983 1995 and dumont d urville 1991 1997 at dumont d urville and neumayer the non sea salt sulfate nssso42 level observed from october 1991 to october 1993 exceeded by 44 and 48 ng m 3 respectively the mean level 150 ng m 3 observed during nonvolcanic years the neumayer and dumont d urville records first exhibit spring october to december 1991 nssso42 concentrations exceeding mean spring concentrations by some 100 to 150 ng m 3 caused by a significant poleward transport of the cerro hudson volcanic aerosol in the lower stratosphere beneath the polar vortex and possibly in the middle upper troposphere limited to 10 ng m 3 during winter 1992 the nssso42 perturbation reached 78 ng m 3 in fall 1993 at neumayer the latter enhancement corresponds to the input of the pinatubo volcanic aerosol advected through stratosphere troposphere air mass exchanges an enhancement of nssso42 concentrations is also recorded in snow layers deposited between 1991 and 1993 at various sites located over the high antarctic plateau on the basis of these firn data the relative impact of the three latest volcanic eruptions of global concern namely mount agung 1963 el chichon 1982 and pinatubo together with cerro hudson 1991 was evaluated in terms of sulfate input at high southern latitudes the fallout of sulfate in central antarctic snow following the cerro hudson pinatubo eruptions was slightly lower than fallout after the mount agung eruption sulfate fallout after el chichon was 2 to 3 times lower than that from either mount agung or pinatubo the enhancement of sulfate levels detected in central antarctic snow deposits during the 1991 1993 time period allows us to estimate a mean atmospheric sulfate perturbation of around 60 ng m 3 in the boundary layer of these regions i e at least 35 higher than that seen at coastal sites this observation suggests that coastal antarctic regions are less sensitive than the high plateau in detecting volcanic sulfate fallouts following eruptions of global concern atmospheric near surface year round sampling achieved at coastal antarctic sites reveals no significant enhancement of the nitrate level over 1992 and 1993 suggesting that volcanic aerosols have had a limited effect on the transfer of nitric acid from the lower antarctic stratosphere to the boundary layer in these regions

characteristics of accumulation around the epica deep drilling site in dronning maud land antarctica based on ground penetrating radar profiles we analyze area wide spatial and temporal characteristics of accumulation rate in the vicinity of the epica european project for ice coring in antarctica deep drilling site in dronning maud land antarctica edml an area of 1600 km 2 is covered by 500 km of radar profiles organized in a star like pattern with eight 20 25 km legs and a 10 km grid with 1 3 km spacing each pattern being centred on the edml drilling location distributions of density cumulative mass age and the electromagnetic wave speed with depth are available from physical ice core records nine internal reflection horizons are continuously tracked within the upper 110 m of ice over the whole area yielding a spatial picture of accumulation rate history over 1000 years the mean accumulation rate over the last 153 years varies between 50 and 75 kg m 2 a 1 over 50 km perpendicular to the ice divide the spatial average is 61 kg m 2 a 1 this general pattern is overlain by small scale variations of accumulation rate on the order of 10 of the mean maximum local gradients in accumulation rate are 2 3 kg m 2 a 1 km 1 about five times the regional accumu lation rate gradient comparison of topography and accumulation rate along a 20 km profile in the direction of the mean winds indicates that variations in accumulation rate over short distances are linked to surface undulations our results show that advected spatial variations of accumulation rate are on the same order and even exceed temporal changes over the investigated periods ice flow and upstream effects therefore might influence accumulation rates reconstructed from the edml ice core

assessment of the record of the 1982 el chichon eruption as preserved in greenland snow variability in the so42 and cl time series for the 1980s from 12 shallow snow pits across the greenland ice sheet is used to evaluate the record of the 1982 el chichon eruption and the potential for recording a moderate northern equatorial eruption in a single greenland ice core composition of volcanic glass found in spring 1983 snow in one of the pits in the summit region matches that from el chichon glass thereby verifying the deposition of material from the eruption high na and cl concentrations in this same layer probably represent deposition of the reaction products of halite and h2so4 as observed in the stratosphere following the eruption these findings and the presence of a cl signal in five of the other pits indicate that the cl aerosol component of some eruptions has the potential to remain aloft for at least 1 year after the eruption some of these aerosols may be adsorbed onto tephra particles distinct so42 peaks that can be confidently linked to el chichon were found in only 50 of the records developed through subseasonal sampling however in several other pits an elevated baseline thought to represent more lengthy periods of el chichon aerosol deposition as opposed to deposition from a single snowfall event were observed smoothing of the original data by the calculation of annual so42 flux resulted in the presence of high flux values between 1982 and 1984 years thought to be affected by el chichon aerosol deposition in 9 of the 12 pits these results suggest that a single ice core from anywhere in greenland may record a signal from a northern equatorial eruption of magnitude similar to that of el chichon about 75 of the time this is despite the overall high levels of so2 4 deposition from anthropogenic sources that now make identification and quantification of the volcanic so2 portion of the record more difficult than obtaining the same data for preindustrial volcanism nevertheless composite records from all the pits sampled yielded stratospheric loading 20 mt and optical depth 0 13 estimates similar to stratospheric and satellite based measurements following the eruption equally high so42 concentration and flux values in snow from 1980 to 1982 reflect deposition from the series of middle to high northern latitude volcanic eruptions 1979 1981

a 1500 year record of accumulation at amundsenisen western dronning maud land antarctica derived from electrical and radioactive measurements on a 120 m ice core during the nordic epica pre site survey in dronning maud land in 1997 1998 a 120 m long ice core was retrieved 76 00 s 08 03 w 2400 m above sea level the whole core has been measured using the electric conductivity measurement ecm and dielectric profiling dep techniques and the core chronology has been established by detecting major volcanic eruptions in a nearby shallow core radioactive traces from nuclear tests conducted during the 1950s and 1960s have been identified altogether 13 ecm and dep peaks in the long core are identified as originating from specific volcanic eruptions in addition two peaks of increased total activity are identified in the short core accumulation is calculated as averages over the time periods between these dated events accumulation rate is 62 millimetres w eq yr for the last 181 years 1816 a d to present and 61 mm w eq yr for the last 1457 years 540 a d to present our record shows an 8 decrease in accumulation between 1452 and 1641 a d i e part of the little ice age compared to the long term mean

volcanic forcing of climate over the past 1500 years an improved ice core based index for climate models 1 understanding natural causes of climate change is vital to evaluate the relative impacts of human pollution and land surface modification on climate we have investigated one of the most important natural causes of climate change volcanic eruptions by using 54 ice core records from both the arctic and antarctica our recently collected suite of ice core data more than double the number of cores ever used before reduces errors inherent in reconstructions based on a single or small number of cores which enables us to obtain much higher accuracy in both detection of events and quantification of the radiative effects we extracted volcanic deposition signals from each ice core record by applying a high pass loess filter to the time series and examining peaks that exceed twice the 31 year running median absolute deviation we then studied the spatial pattern of volcanic sulfate deposition on greenland and antarctica and combined this knowledge with a new understanding of stratospheric transport of volcanic aerosols to produce a forcing data set as a function of month latitude and altitude for the past 1500 years we estimated the uncertainties associated with the choice of volcanic signal extraction criteria ice core sulfate deposition to stratospheric loading calibration factor and the season for the eruptions without a recorded month we forced an energy balance climate model with this new volcanic forcing data set together with solar and anthropogenic forcing to simulate the large scale temperature response the results agree well with instrumental observations for the past 150 years and with proxy records for the entire period through better characterization of the natural causes of climate change this new data set will lead to improved prediction of anthropogenic impacts on climate the new data set of stratospheric sulfate injections from volcanic eruptions for the past 1500 years as a function of latitude altitude and month is available for download in a format suitable for forcing general circulation models of the climate system

grains in motion a review abstract this review paper aims to present a practical integrated procedure for the prediction of sediment transport rates in both the continental and marine environment based on the settling velocity of particles such studies have important applications in diverse fields such as civil and coastal engineering sedimentology and environmental geology where they can assist in flood control and the prevention of contaminant dispersal by wind and water as well as the siltation of dams and harbours the formation of placer deposits including gold diamonds and other heavy minerals is also controlled by sediment transport processes so that these studies can form the basis for more efficient exploration programs the first part of the paper discusses some basic principles important in sediment transport followed by an overview of published methods to determine the settling velocity of differently shaped particles including natural grains the application of settling velocity to predict the entrainment threshold of sediments on plane horizontal and inclined beds by unidirectional currents and oscillatory waves is then discussed which finally leads to the determination of sediment transport rates over plane and rippled beds the validity of this approach to natural conditions is tested against published field data where possible other widely used methods are also critically discussed pointing out severe problems in current sampling technology and the calculation of bedload transport in natural environments

accumulation rates in dronning maud land antarctica as revealed by dielectric profiling measurements of shallow firn cores the european programme for ice coring in antarctica includes a comprehensive pre site survey on the inland ice plateau of dronning maud land antarctica the german glaciological programme during the 1997 98 field season was carried out along a 1200 km traverse on amundsenisen and involved sampling the snow cover in pits and by shallow firn cores this paper focuses on the accumulation studies the cores were dated by dielectric profiling and continuous flow analysis distinct volcanogenic peaks and seasonal signals in the profiles served to establish a depth time scale the eruptions of krakatoa tambora an unknown volcano kuwae and el chichon are well documented in the ice variations of the accumulation rates over different times were inferred from the depth time scales a composite record of accumulation rates for the last 200 years was produced by stacking 12 annually resolved records according to this accumulation rates decreased in the 19th century and increased in the 20th century the recent values are by no means extraordinary as they do not exceed the values at the beginning of the 19th century variations in accumulation rates are most probably linked to temperature variations indicated in 18o records from amundsenisen

antarctic volcanic flux ratios from law dome ice cores 3 climatestudiescenter institutefor quaternarystudies universityofmaine orono me 04469 5717 u s a abstract explosivevolcanic eruptions can inject largequantitiesof sulphur dioxide intothe stratosphere theaerosolsthat result fromoxidationof thesulphur dioxidecanpro duce significant cooling of the troposphere by reflecting or absorbing solar radiation it is possibleto obtainanestimateoftherelativestratosphericsulphuraerosolconcentrationpro duced by different volcanoes by comparing sulphuric acid fluxes determined by analysis of polaricecores here weuseanon sea saltsulphatetimeseriesderivedfromthreewell dated law dome ice cores to investigate sulphuric acid flux ratios for major eruptions over the period ad1301 1995 weuseadditionaldata fromothercorestoinvestigatesystematicspa tial variability in the ratios only for the kuwae eruption law dome ice date ad1459 5 wasthe h2so4 flux largerthanthatdepositedbytambora law domeicedate ad1816 7

european summer temperature response to annually dated volcanic eruptions over the past nine centuries the drop in temperature following large volcanic eruptions has been identified as an important component of natural climate variability however due to the limited number of large eruptions that occurred during the period of instrumen tal observations the precise amplitude of post volcanic cooling is not well constrained here we present new evidence on summer temperature cooling over europe in years following volcanic eruptions we compile and analyze an updated net work of tree ring maximum latewood density chronologies spanning the past nine centuries and compare cooling sig natures in this network with exceptionally long instru mental station records and state of the art general circu lation models results indicate post volcanic june august cooling is strongest in northern europe 2 years after an eruption 0 52 0 05 c whereas in central europe the temperature response is smaller and occurs 1 year after an eruption 0 18 0 07 c we validate these estimates by comparisonwith the shorter instrumental network and evaluate the statistical significance of post volcanic summer tempera ture cooling in the context of natural climate variability over the past nine centuries finding no significant post volcanic temperature cooling lasting longer than 2 years our results question the ability of large eruptions to initiate long term temperature changes through feedback mechanisms in the climate system we discuss the implications of these findings with respect to the response seen in general circulation models and emphasize the importance of considering well documented annually dated eruptions when assessing the

drilling to gabbro in intact ocean crust sampling an intact sequence of oceanic crust through lavas dikes and gabbros is necessary to advance the understanding of the formation and evolution of crust formed at mid ocean ridges but it has been an elusive goal of scientific ocean drilling for decades recent drilling in the eastern pacific ocean in hole 1256d reached gabbro within seismic layer 2 1157 meters into crust formed at a superfast spreading rate the gabbros are the crystallized melt lenses that formed beneath a mid ocean ridge the depth at which gabbro was reached confirms predictions extrapolated from seismic experiments at modern mid ocean ridges melt lenses occur at shallower depths at faster spreading rates the gabbros intrude metamorphosed sheeted dikes and have compositions similar to the overlying lavas precluding formation of the cumulate lower oceanic crust from melt lenses so far penetrated by hole 1256d

annually resolved southern hemisphere volcanic history from two antarctic ice cores the continuous sulfate analysis of two antarctic ice cores one from the antarctic peninsula region and one from west antarctica provides an annually resolved proxy history of southern semisphere volcanism since early in the 15th century the dating is accurate within 3 years due to the high rate of snow accumulation at both core sites and the small sample sizes used for analysis the two sulfate records are consistent with each other a systematic and objective method of separating outstanding sulfate events from the background sulfate flux is proposed and used to identify all volcanic signals the resulting volcanic chronology covering 1417 1989 a d resolves temporal ambiguities about several recently discovered events a number of previously unknown moderate eruptions during late 1600s are uncovered in this chronology the eruption of tambora 1815 and the recently discovered eruption of kuwae 1453 in the tropical south pacific injected the greatest amount of sulfur dioxide into the southern hemisphere stratosphere during the last half millennium a technique for comparing the magnitude of volcanic events preserved within different ice cores is developed using normalized sulfate flux for the same eruptions the variability of the volcanic sulfate flux between the cores is within 20 of the sulfate flux from the tambora eruption

high precision dating of volcanic events a d 1301 1995 using ice cores from law dome antarctica a record of volcanic activity over the period a d 1301 1995 has been extracted from three law dome ice cores east antarctica the record dating is unambiguous at the annual level from a d 1807 to 1995 and has an uncertainty of 1 year at a d 1301 signals from 20 eruptions are preserved in the record including those of two unknown eruptions with acid deposition beginning in a d 1810 8 and a d 1685 8 the beginning of the ice core signal from the a d 1815 tambora eruption is observed in the austral summer of a d 1816 1817 the mean observed stratospheric transport and deposition time to law dome from the eruption site is 1 5 years 0 6 years from 11 well dated eruptions the largest eruption observed in the law dome record has its maximum in a d 1460 with volcanic sulfate deposition beginning in the austral winter of a d 1459 this event is also observed in other ice core records and is attributed to the volcano kuwae with an eruption date in the range a d 1455 9 1459 9 if all sources of error are considered this is at least three years later than the date previously ascribed by dendrochronological and historical studies

ammonium and non sea salt sulfate in the epica ice cores as indicator of biological activity in the southern ocean sulfate so42 and ammonium nh4 flux records over the last 150 000 years from both antarctic epica ice cores european project for ice coring in antarctica are presented the ice core record from dome c is influenced by the indian sector of the southern ocean so whereas dronning maud land is facing the atlantic sector generally they reflect the past atmospheric aerosol load and thus potentially reveal the fingerprint of marine biogenic sources from the so the most important feature of both the nssso 4 2 as well as nh4 flux records is the absence of any significant glacial cycles in contrary to the distinct transitions for mineral dust and sea salt aerosol over the last 150 000 years this finding challenges the iron fertilization hypothesis on long time scales as the significant changes in dust e g from the last glacial maximum toward the holocene have neither an impact on nssso 4 2 nor on nh4 fluxes found in interior antarctica the inter site correlation of both species is weak r 2 0 42 for the nssso 4 2 flux and r 2 0 12 for the nh4 flux respectively emphasizing the local source characteristics of biogenic aerosol from the so millennial variability in nh4 and nssso 4 2 is within the uncertainty of our flux estimates correlation with mineral dust and sea ice derived sodium shows only a very weak influence of dust deposition on those insignificant changes in nssso 4 2 flux for the atlantic sector of the southern ocean but also small transport changes or terrigeneous sulfate contributions may contribute to those variations at edml c 2009 elsevier ltd all rights reserved

temporal and spatial variation of stable isotope ratios and accumulation rates in the hinterland of neumayer station east antarctica four firn cores were retrieved in 2007 at two ridges in the area of the ekstrom ice shelf dronning maud land coastal east antarctica in order to investigate the recent regional climate variability and the potential for future extraction of an intermediate depth core stable water isotope analysis tritium content and electrical conductivity were used to date the cores for the period 1981 2006 a strong and significant correlation between the stable isotope composition of firn cores in the hinterland and mean monthly air temperatures at neumayer station was r 0 54 0 71 no atmospheric warming or cooling trend is inferred from our stable isotope data for the period 1962 2006 the stable isotope record of the ice firn cores could expand well beyond the meteoro logical record of the region no significant temporal variation of accumulation rates was detected however decreasing accumulation rates were found from coast to hinterland as well as from east halvfarryggen to west sorasen the deuterium excess d exhibits similar differences higher d at sorasen lower d at halvfarryggen with a weak negative temporal trend on halvfarryggen 0 04 a 1 probably implying increasing oceanic input we conclude that halvfarryggen acts as a natural barrier for moisture carrying air masses circulating in the region from east to west

record of volcanism since 7000 b c from the gisp2 greenland ice core and implications for the volcano climate system sulfate concentrations from continuous biyearly sampling of the gisp2 greenland ice core provide a record of potential climate forcing volcanism since 7000 b c although 85 percent of the events recorded over the last 2000 years were matched to documented volcanic eruptions only about 30 percent of the events from 1 to 7000 b c were matched to such events several historic eruptions may have been greater sulfur producers than previously thought there are three times as many events from 5000 to 7000 b c as over the last two millennia with sulfate deposition equal to or up to five times that of the largest known historical eruptions this increased volcanism in the early holocene may have contributed to climatic cooling

spatial distribution of surface mass balance on amundsenisen plateau antarctica derived from ice penetrating radar studies the distribution of surface mass balance on amundsenisen dronning maud land antarctica is investigated along a continous profile line ice penetrating radar is used to map variations in ice layer thickness within the upper 100 m of the ice sheet the route passes several firn and ice core drilling sites over a distance of 320 km dielectric profiling data of ice cores is used to calculate the depths of selected reflection horizons and the cumulative mass of the ice column the local surface mass balance is determined as a temporal average covering a time span of almost two centuries the findings indicate a complex accumulation pattern superimposed on a general low surface mass balance which is related to small scale surface undulations the results of the radar soundings are in general in good agreement with surface mass balance data derived from firn core studies discrepancies between these two datasets can be explained by spatial mismatch or by minor quality of either ice core profiles or radar data for regional comparison of radar based accumulation data we use an accumulation distribution interpolated from point measurements the surface mass balance varies up to 50 over short distances with correlation lengths of 10 km we conclude that the current utilization schemes of point sampling are only capable of reproducing local values and regional trends but provide no information on the small scale variability of surface mass balance

an 860 km surface mass balance profile on the east antarctic plateau derived by gpr abstract snow accumulation and its variability on the east antarctic plateau are poorly understoodduetosparseandregionallycon nedmeasurements wepresenta5 3ghz c band ground penetratingradar gpr pro lewith atotal length of860kmrecovered duringthe jointnorwegian us internationalpolar year traverse 2007 08 mean surface mass balance smb over the last 200years was derived fromthe gpr data by identifying the volcanic deposition of the tambora eruption in 1815 it varies between9 1 and 37 7kgm 2 a 1 over the pro le with a mean of 23 7kgm 2 a 1 and a standard deviation of4 7kgm 2 a 1 the 200year smb estimated is signi cantly lower than most of the smb estimates overshorter time periods in this region this can be partly explained by a smb minimum in the vicinity ofthe ice divide however it is more likely that a recent increase in smb observed by several studies islargely responsible for the observed discrepancy introduction many recent studies have concentrated on the surface massbalance smb vaughan and others 1999 arthern andothers 2006 monaghan and others 2006 van de berg andothers 2006 and mass changes davis and others 2005 zwally and others 2005 of the antarctic ice sheet in orderto assess antarctica s contribution to changes in global sealevel new techniques such as radar altimetry have madeit possible to study continent wide elevation changes withhigh accuracy these changes are often related to changesin precipitation on the east antarctic plateau eap davisand others 2005 zwally and others 2005 however thesetechniques only cover short time periods it is important toobtain ground truth over longer time periods to understandhow observed changes relate to the past to date there have been very few in situ measurements ofsmb available from the interior of the eap the present smbestimates are mainly based on remote sensing e g arthernand others 2006 or numerical modelling e g monaghanand others 2006 van de berg and others 2006 calibratedby very sparse in situ measurements for the interior ofthe continent there are also indications that there are anon negligible number of zero accumulation sites so calledglazedareas intheinterioroftheeapthatareoftennottakeninto account by mass balance estimates and can changetheirvalue signi cantly frezzotti andothers 2002 scambosandothers 2008 it isclear that moreaccumulation dataarerequired to study the spatial and temporal variability of smband to improve the spatial resolution and accuracy of large scale accumulation studies the smb is the aggregate of many processes such asprecipitation from clouds and clear skies the formationof hoar frost at the surface and within the snowpack sublimation melting and runoff wind scouring and driftdeposition eisen and others 2008 snow accumulation canbe derived using various methods e g eisen and others 2008 snow pit rn and ice core studies provide valuableinformation about mean smb for a certain point location takahashi and others 1994 isaksson and others 1996 ansch utz and others in press these point measurementscan be spatially extended by ground penetrating radar gpr smb is proportional to the re ector depth withinthe rn pack as variations in vertical strain rates can beneglected in the top tens of metres of the ice sheet nye 1963 gpr has previously been successfully used to followisochronous rn layers providing detailed information aboutthe smb variability across antarctica fujita and others 1999 richardson naslund 2004 rotschky and others 2004 spikes and others 2004 arcone and others 2005a although large regions of the eap still remain uncovered we show smb derived by gpr data collected duringthe rst leg of the norwegian us scienti c traverse ofeastantarctica http traverse npolar no duringthe2007 08austral summer nus07 this joint project is part of thelarger trans antarctic scienti c traverses expeditions icedivideofeast antarctica taste idea andthe internationalpartnerships in ice coringsciences ipics goldman 2008

quantifying the pinatubo volcanic signal in south polar snow recent snow and firn core samples from south pole contain increased sulfate so42 concentrations during 1992 1994 as a result of the june 1991 pinatubo eruption and the august 1991 cerro hudson eruption in chile traces of pinatubo tephra volcanic ash were identified in the 1993 and 1994 snow layers supporting the conclusion that increased so42 in 1993 1994 is from the pinatubo eruption although the pinatubo eruption preceded hudson its so42 signal in south polar snow follows and is resolved from that of hudson the deposition of the pinatubo so42 aerosol was delayed due to the long transport to the high southern latitudes and its initial existence at high altitudes in the antarctic atmosphere multi year multi site sampling demonstrates that the volcanic signals are well preserved and spatially consistent measurements on 2 firn cores show that the south pole so so42 flux from pinatubo is 10 9 1 2 kg km 2 over 2 2 years while the hudson flux is 3 2 0 6 kg km 2 in 1 1 years these results when combined with satellite determined pinatubo sulfur dioxide so2 emission make it possible to link quantitatively the atmospheric aerosol mass loading from a low latitude volcanic eruption to its signal in polar ice cores

volcanic aerosol records and tephrochronology of the summit greenland ice cores the recently collected greenland ice sheet project 2 gisp2 and greenland ice core project ice cores from summit greenland provide lengthy and highly resolved records of the deposition of both the aerosol h2so4 and silicate tephra components of past volcanism both types of data are very beneficial in developing the hemispheric to global chronology of explosive volcanism and evaluating the entire volcanism climate system the continuous time series of volcanic so42 for the last 110 000 years show a strong relationship between periods of increased volcanism and periods of climatic change the greatest number of volcanic so42 signals many of very high magnitude occur during and after the final stages of deglaciation 6000 17 000 years ago possibly reflecting the increased crustal stresses that occur with changing volumes of continental ice sheets and with the subsequent changes in the volume of water in ocean basins sea level change the increase in the number of volcanic so42 signals at 27 000 36 000 and 79 000 85 000 years ago may be related to initial ice sheet growth prior to the glacial maximum and prior to the beginning of the last period of glaciation respectively a comparison of the electrical conductivity of the gisp2 core with that of the volcanic so42 record for the holocene indicates that only about half of the larger volcanic signals are coincident in the two records other volcanic acids besides h2so4 and other so42 sources can complicate the comparisons although the threshold level picked to make such comparisons is especially critical tephra has been found in both cores with a composition similar to that originating from the vatnaoldur eruption that produced the settlement layer in iceland mid a d 870s from the icelandic eruption that produced the saksunarvatn ash 10 300 years ago and from the icelandic eruption s that produced the z2 ash zone in north atlantic marine cores 52 700 years ago the presence of these layers provides absolute time lines for correlation between the two cores and for correlation with proxy records from marine sediment cores and terrestrial deposits containing these same tephras the presence of both rhyolitic and basaltic shards in the z2 ash in thegisp2 core and the composition of the basaltic grains lend support to multiple icelandic sources torfajokull area and katla for the z2 layer deposition of the z2 layer occurs at the beginning of a stadial event further reflecting the possibility of a volcanic triggering by the effects of changing climatic conditions

accumulation studies on amundsenisen dronning maud land antarctica by means of tritium dielectric profiling and stable isotope measurements first results from the 1995 96 and 1996 97 field seasons the paper focuses on studies of snow pit samples and shallow firn cores taken during the 1995 96 and 1996 97 field seasons at amundsenisen dronning maud land antarctica the dating of the firn is based on the artificial tritium distribution in the snow cover and on several reference horizons identified by electrical measurements the early 1964 through 1965 horizon is marked by the deposition of sulfate released to the atmosphere during the eruption of the agung volcano in march 1963 this horizon was detected by dielectric profiling and electrical conductivity measurements the proof by chemical analysis has still to be seen at the ten investigated sites on amundsenisen the 1964 65 horizon was identified 4 1 5 7 m below the surface the accumulation rates on amundsenisen are 41 91kg ma the cores are up to 100 years old a relationship between isotope content and the mean air temperature on a regional scale can be based onmeasurements of firn temperature at10m depth at the drilling sites betweenneumayer station at the coast and heimefrontfjella the temperature gradient of the deuterium content is 9 6 k south of heimefrontfjella on the amundsenisen plateau it is only 5 5 k time series of yearly accumulation rates show no significant trend for the isotope records a significant trend to higher values with gradients of 0 1 0 2 dh a can be seen in five of the ten time series

ice cores as an index of global volcanism from 1850 to the present to evaluate an important cause of past climate change climate researchers need reliable estimates of volcanic aerosol loading in the atmosphere previous indices the dust veil index volcanic explosivity index and those by mitchell 1970 sato et al 1993 and khmelevtsov et al unpublished manuscript 1993 all have drawbacks ice core acidity and sulfate records because they contain physical evidence of atmospheric loading are a promising source of information on past volcanic aerosols but these records contain large nonvolcanic signals as well we have compared northern hemisphere nh and southern hemisphere sh annual average versions of five indices with eight nh and six sh ice core records for the period 1850 to the present in an attempt to identify the volcanic signal common to all records the indices are all highly correlated with each other for the nh although the individual ice core records are in general not well correlated with each other or with any of the indices a composite derived from averaging the cores the ice core volcano index ivi shows promise as a new index of volcanic aerosol loading this new index correlates well with the existing non ice core volcanic indices and with high frequency temperature records for the sh the individual ice cores and indices are better correlated the shivi is again highly correlated with all indices and individual ice cores but not with high frequency temperature records for both hemispheres the southern oscillation index shows no significant correlation with the volcanic indices ice cores or the ivi thus providing no evidence for the impact of volcanic eruptions on el nino southern oscillation events

a comparison of the volcanic records over the past 4000 years from the greenland ice core project and dye 3 greenland ice cores since 1980 the electrical conductivity method ecm has been used to infer volcanic acid signals in greenland ice cores the method reveals the great majority of major volcanic eruptions including several known from historic records subsequent ion chromatographic analyses of the acid volcanic layers show the chemical composition i e the concentration of the volcanic acids h2so4 hci and hf plus e g the nonvolcanically derived hno3 while ecm data are available from a large number of shallow depth greenland ice cores covering the past 500 1500 years only the greenland ice core project grip greenland ice sheet project 2 gisp2 and dye 3 deep ice cores exist for a detailed comparative study of volcanic signals in greenland ice cores representing several thousand years comparison of the volcanic signals registered in the grip and gisp2 cores will be presented elsewhere the latter cores were augered 30 km apart and essentially represent the same atmospheric conditions such as temperature snow accumulation and chemical composition of the air here we present a comparison between the major volcanic signals over the past 4000 years in the grip core from central greenland and the dye 3 core from se greenland in order to investigate the depositional differences many of the major signals are detected in both cores but some of the differences in the records can be used to infer the latitudinal band of some eruption sites furthermore the influence of the amount of annual precipitation and glaciological postdepositional processes on the volcanic signals is discussed

a glacio chemical characterization of the new epica deep drilling site on amundsenisen dronning maud land antarctica in the framework of the european project for ice coring in antarctica epica a glacio chemical pre sitesurvey was carried out in dronning maud land dml antarctica up to now three intermediate deep icecores and twelve snow pits have been analysed by ion chromatography the spatial and seasonal variationsof the snow chemistry in dml covering the time period 1997 to 1865 are presented summer maxima insulphate and winter maxima in sea salt components are well archived in the area under investigation while for nitrate and methanesulphonic acid msa seasonal variations could not be unambiguouslydetected due to postdepositional changes average concentrations of sea salt components and nitrateare spatially uniform in the plateau region however sea salt shows an exponential decline with altitudefor elevations below 2800 m a s l non seasalt sulphate shows a 40 increase with lower snowaccumulation while msa shows a 50 decline with higher elevation and lower accumulation the outcomeof this study supports that the data of the new epica deep drilling site in dml 0 04 07 e 75 00 10 s will be geographical representative for this region high resolution analytical methods will allow accuratestratigraphic dating of the core at least for the holocene period

use of paleo records in determining variability within the volcanism climate system abstract volcanic eruptions that inject large quantities of sulfur rich gases into the stratosphere have the capability of cooling global climate by 0 2 0 3 c for several years after the eruption equatorial eruptions will impact global climate whereas mid latitude eruptions can cool climate in the hemisphere of origin magnitude of cooling varies by latitude and it is possible for warming to occur in certain regions primarily during the winter although instrumental records have been used to quantify the volcanic impact on climate they are limited in their temporal and spatial coverage and the style and magnitude of eruptions occurring over the two centuries of instrumental records is limited a thorough evaluation of the range of variability in the volcanism climate system requires a multidisciplinary approach that includes the analysis of ice core records geological data atmospheric measurements and visual phenomena tree ring records and other proxy data evaluation of these longer time series indicates that multiple volcanic eruptions have the potential to force climate over decadal to multi decadal time frames especially when these eruptions enhance or extend pre existing cool conditions on the other hand a lack of climatically significant eruptions may result in warmer average temperatures over decadal time frames because the volcanic cooling component within the climate system is absent mega eruptions like the toba eruption of 71 000 73 000 yr ago may impact climate on centennial time frames through positive feedback mechanisms evidence exists which indicates that environmental changes associated with rapid climatic fluctuations such as crustal loading unloading with glaciation deglaciation and variability in glacial meltwater loading on ocean basins may cause an increase in volcanic activity

glacio chemical study spanning the past 2 kyr on three ice cores from dronning maud land antarctica 2 seasonally resolved chemical records the ammonium calcium and sodium concentrations from three intermediate depth ice cores drilled in the area of dronning maud land east antarctica have been investigated since all measurements were performed by a high resolution continuous flow analysis system for the first time seasonal signals of chemical trace species could be obtained from the interior of central antarctica over a period of approximately 2 millennia although the elevation as well as the accumulation rate differ between the drilling sites similar values were obtained by comparing mean concentrations spanning the last 900 years however a distinct lack of intersite correlation was found on decadal timescales despite a noticeable accumulation change apparent in one core no significant concentration change of all three species has occurred all the measured ions show clear seasonal signals over the whole records while the sea salt related component sodium peaks simultaneously with calcium the maximum ammonium concentration occurs in the snow with a time lag of 2 months after the sea salt peak more than 60 of the calcium concentration can be attributed to an ocean source elevated sodium concentrations were found within this millennium compared to mean values of the whole records but the spatially varying shape of the increase suggests that a possible climatic signal is biased by local deposition effects

consistent dating for antarctic and greenland ice cores we are hereby presenting a new dating method based on inverse techniques which aims at calculating consistent gas and ice chronologies for several ice cores the proposed method yields new dating scenarios simultaneously for several cores by making a compromise between the chronological information brought by glaciological modeling i e ice flow model firn densification model accumulation rate model and by gas and ice stratigraphic constraints this method enables us to gather widespread chronological information and to use regional or global markers i e methane volcanic sulfate beryllium 10 tephra layers etc to link the core chronologies stratigraphically confidence intervals of the new dating scenarios can be calculated thanks to the probabilistic formulation of the new method which takes into account both modeling and data uncertainties we apply this method simultaneously to one greenland ngrip and three antarctic epica dome c epica dronning maud land and vostok ices cores and refine existent chronologies our results show that consistent ice and gas chronologies can be derived for depth intervals that are well constrained by relevant glaciological data in particular we propose new and consistent dating of the last deglaciation for greenland and antarctic ice and gas records

atmospheric methane sulfonate and non sea salt sulfate records at the european project for ice coring in antarctica epica deep drilling site in dronning maud land antarctica abstract during three summer campaigns in january february 2000 2001 and 2002 the ionic compo sition of the aerosol at the epica deep drilling site at kohnen station was measured in daily resolution in 2000 and 2002 we observed mean std non sea salt sulfate nss so42 con centrations of 353 100 ng m 3 and 320 250 ng m 3 as well as methane sulfonate ms con centrations of 59 36 ng m 3 and 74 80 ng m 3 respectively for the summer campaign in 2001 significantly lower nss so42 and ms levels of 164 150 ng m 3 and 19 12 ng m 3 respectively were typical the mean ms nss so42 ratio ranged from about 0 1 to 0 2 ms and nss so42 concentrations and their variability were roughly comparable to coastal stations at summer supported by air mass back trajectory analyses this finding documented an effi cient long range transport to kohnen via the free troposphere ms nss so42 ratios exhibited a strong dependence on the ms concentration with systematically higher ratios at higher ms concentrations a peculiarity which is also evident in a firn core drilled at this site

eight centuries of volcanic signal and climate change at talos dome east antarctica 1 during the 1996 programma nazionale di ricerche in antartide international trans antarctic scientific expedition traverse two firn cores were retrieved from the talos dome area east antarctica at elevations of 2316 m td 89 m long and 2246 m st556 19 m long cores were dated by using seasonal variations in non sea salt nss so42 concentrations coupled with the recognition of tritium marker level 1965 1966 and nss so42 spikes due to the most important volcanic events in the past pinatubo 1991 agung 1963 krakatoa 1883 tambora 1815 kuwae 1452 unknown 1259 the number of annual layers recognized in the td and st556 cores was 779 and 97 respectively the d record obtained from the td core has been compared with other east antarctic isotope ice core records dome c epica south pole taylor dome these records suggest cooler climate conditions between the middle of 16th and the beginning of 19th centuries which might be related to the little ice age lia cold period because of the high degree of geographical variability the strongest lia cooling was not temporally synchronous over east antarctica and the analyzed records do not provide a coherent picture for east antarctica the accumulation rate record presented for the td core shows a decrease during part of the lia followed by an increment of about 11 in accumulation during the 20th century at the st556 site the accumulation rate observed during the 20th century was quite stable

an inter hemispheric volcanic time marker in ice cores from greenland and antarctica a strong volcanic acid signal is clearly registered using an acidity measuring technique in the a d 1259 ice layer in four different greenland ice cores camp century milcent crete and dye 3 this signal is similar in amplitude to the laki iceland a d 1783 volcanic event as recorded in the central and south greenland ice cores measurement of ice layers from corresponding age levels in antarctic ice cores byrd station south pole and j 9 on the ross ice shelf provides similar strong acid signals there is no historical record of a significant volcanic eruption for the period around a d 1260 in the northern hemisphere subsequent chemical analyses of all a d 1259 ice layers show similar compositions we suggest that the a d 1259 signals registered in both greenland and antarctica were caused by the same volcanic disturbance and that its epicenter was located at the earth s equatorial zone which enabled global distribution of the acid gases these results indicate that inter hemispheric dating of ice sheets is possible by the chemical identification of major eruptive volcanic events in the equatorial zone

ground based measurements of spatial and temporal variability of snow accumulation in east antarctica the east antarctic ice sheet is the largest highest coldest driest and windiest ice sheet on earth understanding of the surface mass balance smb of antarctica is necessary to determine the present state of the ice sheet to make predictions of its potential contribution to sea level rise and to determine its past history for paleoclimatic reconstructions however smb values are poorly known because of logistic constraints in extreme polar environments and they represent one of the biggest challenges of antarctic science snow accumulation is the most important parameter for the smb of ice sheets smb varies on a number of scales from small scale features sastrugi to ice sheet scale smb patterns determined mainly by temperature elevation distance from the coast and wind driven processes in situ measurements of smb are performed at single points by stakes ultrasonic sounders snow pits and firn and ice cores and laterally by continuous measurements using ground penetrating radar smb for large regions can only be achieved practically by using remote sensing and or numerical climate modeling however these techniques rely on ground truthing to improve the resolution and accuracy the separation of spatial and temporal variations of smb in transient regimes is necessary for accurate interpretation of ice core records in this review we provide an overview of the various measurement techniques related difficulties and limitations of data interpretation describe spatial characteristics of east antarctic smb and issues related to the spatial and temporal representativity of measurements and provide recommendations on how to perform in situ measurements

a new bipolar ice core record of volcanism from wais divide and neem and implications for climate forcing of the last 2000 years volcanism is a natural climate forcing causing short term variations in temperatures histories of volcanic eruptions are needed to quantify their role in climate variability and assess human impacts we present two new seasonally resolved annually dated non sea salt sulfur records from polar ice cores wais divide wdc06a from west antarctica spanning 408 b c e to 2003 c e and neem neem 2011 s1 from greenland spanning 78 to 1997 c e both analyzed using high resolution continuous flow analysis coupled to two mass spectrometers the high dating accuracy allowed placing the large bi hemispheric deposition event ascribed to the eruption of kuwae in vanuatu previously thought to be 1452 1453 c e and used as a tie point in ice core dating into the year 1458 1459 c e this new age is consistent with an independent ice core timescale from law dome and explains an apparent delayed response in tree rings to this volcanic event a second volcanic event is detected in 1453 c e in both ice cores we show for the first time ice core signals in greenland and antarctica from the strong eruption of taupo in new zealand in 232 c e in total 133 volcanic events were extracted from wdc06a and 138 from neem 2011 s1 with 50 ice core signals predominantly from tropical source volcanoes identified simultaneously in both records we assess the effect of large bipolar events on temperature sensitive tree ring proxies these two new volcanic records synchronized with available ice core records to account for spatial variability in sulfate deposition provide a basis for improving existing time series of volcanic forcing

influence of large scale teleconnection patterns on methane sulfonate ice core records in dronning maud land records of methane sulfonate ms in ice cores from the high plateau of dronningmaud land dml antarctica drilled in the framework of the european project for icecoring in antarctica are investigated for their potential as an environmental andclimate archive for the atlantic sector of the southern ocean despite postdepositionalchanges years of extraordinary ms concentrations can be clearly detected in the icecore records we use composite anomaly maps of atmospheric parameters from thenational centers for environmental prediction national center for atmospheric researchreanalysis fields for years of extreme ms concentration to detect atmospheric patternscausing ms variability changing atmospheric transport is shown to be an important but not exclusive parameter being conserved in the ms record in dml the oftenhypothesized direct link between high ms concentrations and el nino events is notsupported for the observed region whereas the antarctic dipole adp which ismodulated by el nino southern oscillation conditions exerts significant influence aclear 13 9 year cycle can be found throughout a 2000 year ms record that can be relatedto variations in the adp over the last 300 years a 4 6 year cycle is revealed in thems and sea salt record which vanishes in the deeper part of the ice core as aconsequence of diffusion processes from the long term perspective periods of high msconcentrations are connected to on average higher sea salt aerosol as well reflecting aseasonally independent influence of transport on both species a distinctive period ofefficient atmospheric transport probably due to a pronounced adp could be foundfrom 1200 to 1600 a d

a 4100 year record of explosive volcanism from an east antarctica ice core extensive archives of volcanic history are available from ice cores recovered from the antarctic and greenland ice sheets that receive and preserve sulfuric acid fallout from explosive volcanic eruptions the continuous detailed average 1 2 samples per year sulfate measurements of a 200 m ice core from a remote east antarctica site plateau remote provide a record of southern hemisphere volcanism over the last 4100 years this extends the volcanic record beyond the last 1000 years covered by previous antarctic ice cores an average of 1 3 eruptions per century is recorded in east antarctic snow during the last 4100 years the record shows that on average eruptions have been more frequent and more explosive during the most recent 2000 years than in the previous 2100 years intervals up to 500 years are observed in which few explosive volcanic signals are detected these periods include 2000 1500 b c no eruptions 500 1 b c two eruptions and 700 1200 a d two eruptions this new plateau remote volcanic record is compared with those from previous antarctic ice cores covering the last 1000 years in terms of dates for volcanic events the new record is in excellent agreement with the earlier records however significant discrepancies are found between these records in relative signal magnitude volcanic flux of several well known events the discrepancies among the records may be explained by the differences in the glaciology at the ice core sites analytical techniques used for sulfate and sulfuric acid measurement and the selection of detection thresholds for volcanic signals comparison with greenland ice core volcanic records indicates that during the last millennium nine large low latitude eruptions contributed significant amounts of volcanic aerosols to the atmosphere of both hemispheres potentially affecting global climate in contrast only one or possibly two such eruptions are found in the first millennium a d

the 1452 or 1453 a d kuwae eruption signal derived from multiple ice core records greatest volcanic sulfate event of the past 700 years 1 we combined 33 ice core records 13 from the northern hemisphere and 20 from the southern hemisphere to determine the timing and magnitude of the great kuwae eruption in the mid 15th century we extracted volcanic deposition signals by applying a high pass loess filter to the time series and examining peaks that exceed twice the 31 year running median absolute deviation by accounting for the dating uncertainties associated with each record these ice core records together reveal a large volcanogenic acid deposition event during 1453 1457 a d the results suggest only one major stratospheric injection from the kuwae eruption and confirm previous findings that the kuwae eruption took place in late 1452 or early 1453 which may serve as a reference to evaluate and improve the dating of ice core records the average total sulfate deposition from the kuwae eruption was 93 kg so4 km 2 in antarctica and 25 kg so4 km 2 in greenland the deposition in greenland was probably underestimated since it was the average value of only two northern greenland sites with very low accumulation rates after taking the spatial variation into consideration the average kuwae deposition in greenland was estimated to be 45 kg so4 km 2 by applying the same technique to the other major eruptions of the past 700 years our result suggests that the kuwae eruption was the largest stratospheric sulfate event of that period probably surpassing the total sulfate deposition of the tambora eruption of 1815 which produced 59 kg so4 km 2 in antarctica and 50 kg so4 km 2 in greenland