the role of tropical atlantic sst anomalies in modulating western north pacific tropical cyclone genesis the connection between north tropical atlantic nta sea surface temperature sst anomalies and tropical cyclone tc genesis over the western north pacific wnp and associated physical mechanisms are investigated in this study we demonstrate a remarkable negative correlation of wnp tc genesis frequency with the preceding boreal spring nta sst anomalies our analysis suggests that major factors for tc genesis including distributions of large scale vorticity and midtropospheric humidity are rendered unfavorable by remote teleconnections while barotropic energy conversion from the large scale flow is suppressed as shown in recent studies the remote teleconnection from the atlantic is sustained and enhanced throughout the typhoon season through local air sea interactions these results suggest that boreal spring nta sst anomaly could be a new predictor for the seasonal wnp tc activity

the late devensian 22 000 bp irish sea basin the sedimentary record of a collapsed ice sheet margin the late devensian 20 ka bp glacial geology of the irish sea basin 4000 km2 is an event stratigraphy recording the entry of marine waters into a glacio isostatically depressed basin and the rapid retreat of the irish sea glacier as a tidewater ice margin marine limits occur up to 140 m o d across much of the central basin the ice margin was uncoupled from its bed exposing a subglacially scoured topography to glaciomarine processes the irish sea glacier was a major drainage conduit of the last british ice sheet calving of the marine ice margin resulted in fast flow surging of ice streams recorded by drumlin fields around the northern basin margin and tunnel valleys rapid evacuation of the basin may have stranded large areas of dead ice in peripheral zones e g cheshire shropshire lowlands and initiated the collapse of the ice sheet thick wedges of ice contact glaciomarine sediments were deposited during ice retreat as morainal bank complexes by successive tidewater ice margins stabilized at pinning points around the irish sea coast where morainal banks occur on the seaward side of drumlin swarms there is a clear sequential relationship between rapid ice loss from calving ice margins the development of fast flowing ice streams drumlinization and the pumping of subglacial sediment to tidewater raised delta complexes are locally associated with marine limits along the high relief coastal margins of wales east central ireland and the lake district associated valley infill complexes record downslope resedimentation of heterogenous sediments into the marine environment during ice retreat co eval offshore deposits are represented by well stratified glaciomarine complexes that infill a subglacially scoured topography that shows networks of tunnel valleys glaciomarine mud drapes occur well to the south of the maximum limit of grounded ice in the basin e g north devon scilly islands southern ireland the age of these distal sediments previously mapped as pre devensian tills is constrained by amino acid ratios basin rebound following deglaciation was rapid with over 100 m recovery in 3 ka and was followed by a low marine still stand peat accumulating in offshore areas now as much as 55 m below sea level has been drowned by the postglacial eustatic rise in sea level the glacio sedimentary model identified in this paper involving rapid ice retreat and related sedimentation triggered by rising relative sea level suggests that isotatic downwarping is an important mechanism for deglaciating continental shelves

a record of holocene climate change from lake geochemical analyses in southeastern arabia lacustrine sediments from southeastern arabia reveal variations in lake level corresponding to changes in the strength and duration of indian ocean monsoon iom summer rainfall and winter cyclonic rainfall the late glacial holocene transition of the region was characterised by the development of mega linear dunes these dunes became stabilised and vegetated during the early holocene and interdunal lakes formed in response to the incursion of the iom at approximately 8500 cal yr bp with the development of c3 dominated savanna grasslands the iom weakened ca 6000 cal yr bp with the onset of regional aridity aeolian sedimentation and dune reactivation and accretion despite this reduction in precipitation the lake was maintained by winter dominated rainfall there was a shift to drier adapted c4 grasslands across the dune field lake sediment geochemical analyses record precipitation minima at 8200 5000 and 4200 cal yr bp that coincide with bond events in the north atlantic a number of these events correspond with changes in cultural periods suggesting that climate was a key mechanism affecting human occupation and exploitation of this region

intensified interannual relationship between tropical cyclone genesis frequency over the northwest pacific and the sst gradient between the southwest pacific and the western pacific warm pool since the mid 1970s abstractthe sea surface temperature gradient sstg between the southwest pacific swp 40 20 s 160 e 170 w and the western pacific warm pool wwp 0 16 n 125 165 e in boreal spring was revealed to contribute significantly to the interannual variability of tropical cyclone tc genesis frequency over the western north pacific wnp since 1980 the present study extends the analysis back to 1951 results show that the interannual relationship between the sstg and wnp tc genesis frequency is statistically significant only after the mid 1970s while insignificant prior to 1974 further analyses show that the sstg is strongly negatively correlated with the sst anomaly ssta in the central pacific cp in the recent period while with the ssta in the equatorial eastern pacific ep in the prior period in the prior period the spring positive negative ep ssta induces an anticyclonic cyclonic circulation over the wnp this partly offsets the impact of the sstg anomaly on the atmospheric circulation ov

intraseasonal responses of sea surface and deep oceanic temperature anomalies in the northern indian ocean western pacific to the 30 60 day boreal summer atmospheric intraseasonal oscillation the 30 60 day boreal summer atmospheric intraseasonal oscillation bsiso is the predominant intraseasonal variability of the asian summer monsoon and has a strong dynamical and thermodynamical impact on the underlying oceans in the northern indian ocean western pacific this study uses composite analysis of satellite observed sea surface temperature sst data as well as atmospheric and oceanic reanalysis datasets for the period 1998 2013 to identify the intraseasonal behavior of sst and deep ocean temperatures during the life cycle of the bsiso with the bsiso as an organized entity evolving both eastward and northward from the equatorial indian ocean the bsiso induced sst anomalies propagate coherently into several basins including the arabian sea bay of bengal south china sea and western pacific characterized by the alternate occurrence of basin wide positive and negative sst anomalies which primarily respond to the active and suppressed convection phases of the bsiso due to anomalous southwesterlies and northeasterlies together with the resultant surface heating anomalies significant bsiso induced oceanic temperature anomalies occur in the equatorial indian ocean and western pacific with the largest amplitude anomalous signals arising around the thermocline and extending downward into the deep ocean to below 1000 m or more which are associated with the equatorial eastward propagating oceanic kelvin waves forced by anomalous surface wind stress however the local and remote effects of such equatorial oceanic kelvin waves on the sst and deep oceanic temperature anomalies especially north of the equator differ from different basins through the consequential coastal kelvin waves and reflected rossby waves

nao implicated as a predictor of northern hemisphere mean temperature multidecadal variability 1 the twentieth century northern hemisphere mean surface temperature nht is characterized by a multidecadal warming cooling warming pattern followed by a flat trend since about 2000 recent warming hiatus here we demonstrate that the north atlantic oscillation nao is implicated as a useful predictor of nht multidecadal variability observational analysis shows that the nao leads both the detrended nht and oceanic atlantic multidecadal oscillation amo by 15 20 years theoretical analysis illuminates that the nao precedes nht multidecadal variability through its delayed effect on the amo due to the large thermal inertia associated with slow oceanic processes an nao based linear model is therefore established to predict the nht which gives an excellent hindcast for nht in 1971 2011 with the recent flat trend well predicted nht in 2012 2027 is predicted to fall slightly over the next decades due to the recent nao decadal weakening that temporarily offsets the anthropogenically induced warming

final stages in the collapse of the laurentide ice sheet hudson strait canada nwt 14c ams dates seismics stratigraphy and magnetic susceptibility logs hudson strait is a key element in the history of ice sheet ocean interactions during the deglaciation of the laurentide ice sheet data from over 30 giant piston cores supplemented by ca 40 14c ams dates on foraminifers and shells from sites within and adjacent to hudson strait are used to describe the timing and sediment processes associated with the final complex phases of deglaciation in hudson strait each core is placed in a regional seismic architectural context through examination of deep tow huntec profiles most cores sample a thin postglacial unit and extend several meters into glacial marine sediment mainly silty clays 14c dates on cores from the adjacent shelf indicate that deglaciation occurred by 13 ka we have not been unable to confirm that hudson strait was ice free by 11 12 ka although this is a probable scenario whole core magnetic susceptibility wcms data are used as the primary signature of changes in the style of sedimentation and provenance and to correlate between cores wcms indicates that there is a regional differentiation in the ms signal associated with bedrock provenance changes in contribution of detrital carbonate and style of sedimentation one low wcms event is present in cores from both the western and eastern basins it dates from 8 0 ka and provides an important regional stratigraphic marker probably associated with the final deglaciation of hudson bay and hudson strait sediment from a southerly source ungava bay continued to be contributed into the 900 m deep eastern basin of hudson strait 8 and 7 ka and thick postglacial sequences were piled within ungava bay between 6 and 7 ka

particle size related mineral magnetic source sediment linkages in the rhode river catchment maryland usa characterization of both the source materials and the bottom sediments of an estuary by magnetic characters on a particle size basis allows the source of the bottom sediments to be determined and indicates a shift in sediment sources corresponding to changing land use patterns the major source of the sediments in the lower part of cores from the middle of the estuary is eroding shorelines soil derived particulates from the uplands dominate the upper part of the cores this change in source occurred in the early part of the 19th century the magnetic character of the most recent sediments suggests a progressive depletion through time of the upland soils in the finest fractions

compositional variability of ice rafted debris in heinrich layers 1 and 2 on the northwest european continental slope identified by environmental magnetic analyses the composition of ice rafted debris ird within a sediment core from the european continental slope core omex 2k 49 5 n 13 26 w has been examined using environmental magnetic analyses the data demonstrate compositional variability of the ird within heinrich layers 2 h2 and 1 h1 and these differences are most readily explained by changes in the contribution of different ird sources to the core site some ird within the main heinrich layers show magnetic signatures that are similar to ird derived from the laurentide ice sheet found in cores from within the main north atlantic ird belt in contrast other ird rich layers both prior to and within the main heinrich layers demonstrate different magnetic behaviour suggesting a contribution from a non laurentide sourced ird most likely derived from ice streams discharging from northeast atlantic ice sheets such as the british and fennoscandian ice sheets these data are consistent with published compositional data from the same core and given the rapid highly sensitive and non destructive nature of the method suggest that environmental magnetic analysis has considerable potential for characterising ird materials within heinrich layers for the purposes of defining provenance

interdecadal changes in summertime typhoon tracks abstract the present work examines interdecadal variations of typhoon tracks in the western north pacific wnp during the boreal summer june september for the period 1951 2001 typhoon tracks are expressed as percentage values of the total number of typhoon passages into a 5 5 latitude longitude grid box with respect to the total number of typhoons formed in the wnp the analysis period is divided into two interdecadal periods id1 1951 79 and id2 1980 2001 from id1 to id2 typhoon passage frequency decreased significantly in the east china sea and philippine sea but increased slightly in the south china sea the time series of typhoon passage frequency over the east china sea and south china sea further reveal a regime shift in the late 1970s while those over the philippine sea indicate a continuous downward trend of 9 decade 1 the interdecadal changes in typhoon tracks are associated with the westward expansion of the subtropical northwestern pacific high snph in the late 1970s the e

a lacustrine record from lop nur xinjiang china implications for paleoclimate change during late pleistocene abstract climate variability during the late pleistocene is studied from the proxies in core ck 2 drilled from the luobei depression 91 03 e 40 47 n lop nur in the eastern tarim basin xinjiang china geophysical and geochemical properties including magnetic susceptibility granularity chroma carbonate content loss on ignition and trace elements have been determined to reconstruct the environmental evolution of the area during 32 9 ka bp the chronology is established by uranium thorium disequilibrium dating techniques our data suggest four paleoclimate stages indicating glacial variations between cold humid and warm arid environments a period of extreme humidity occurred during 31 900 19 200 yr bp is attributed the last glacial maximum lgm the period was followed by a warm arid episode during 19 200 13 500 yr bp then a cold humid interval during 13 500 12 700 yr bp may correspond to another cooling phases at high latitudes of the northern hemisphere the last stage from 12 700 to 9000 yr bp has a trend that the climate turned warm and arid the lop nur region is characterized by particularly humid stadials and arid interstadials the climate variability in lop nur was constrained by global climate change because it is correlated with dansgaard oeschger and heinrich events which were observed at the northern high latitudes the synchroneity of the palaeoclimatic events suggested that cold air activity at the northern high latitudes was the most important factor that influenced the climate evolution in the lop nur region a probable mechanism that involves the migration of westerly winds is proposed to interpret this synchroneity

mineral magnetic analyses as a means of lithostratigraphic correlation and provenance indication of glacial diamicts intra and interunit variation mineral magnetic analyses are applied to a series of diamict samples taken from the quaternary sequence in the isle of man in order to assess the relative magnitude of the intra and inter unit variation of the magnetic properties the results are analysed both qualitatively and quantitatively and show that the level of intra unit variation is significantly less than the level of inter unit variation the intra unit variation detected appears to show some relationship to the basic stratigraphy previous correlations based upon field evidence of diamict units exposed upon the east and west coasts of the isle of man are supported by their mineral magnetic properties the statistically significant differences in the magnetic mineralogy of the stratigraphically lower wyllin and shellag tills and the upper orrisdale ballavarkish and ballaquark tills suggests distinct provenances for these two suites of sediments allowing potential source areas to be suggested these source areas are consistent with published data on ice flow directions in the irish sea basin during the devensian

glacial characteristics of a pleistocene ice lobe in east central minnesota close scrutiny of the till deposited during the late wisconsin advance of the grantsburg sublobe across east central minnesota enables us to reconstruct the glaciological nature of a mid latitude pleistocene ice lobe the sublobe an offshoot of the des moines lobe advanced to the northeast about 16 000 yr b p overriding drift of the superior lobe an ice mass that had advanced from the lake superior basin approximately 20 000 yr b p because the tills are compositionally distinct variations in grantsburg tills can be discerned that resulted from incorporation of superior lobe drift patterns of grantsburg till dilution can in turn be interpreted to reconstruct some basic physical characteristics of the sublobe to quantify compositional variability analytical methods were selected to characterize the tills texture carbonate content clay mineralogy and magnetic susceptibility when considered jointly adequately distinguish the tills and constitute the means of detecting dilution of grantsburg tills results of analysis indicate that the composition of grantsburg till changes progressively downglacier as a consequence of prolonged contact with superior lobe drift terrane marked variations across the sublobe are also apparent with greater dilution at the margins and relatively lower levels of superior lobe drift incorporation at axial positions this pattern suggests that the grantsburg sublobe was a semipolar ice mass frozen to the substrate at its margin and at its pressure melting point along its axis

comment and reply on glaciomarine sediments of the isle of man as a key to late pleistocene stratigraphic investigations in the irish sea basin reply

the use of mineral magnetic analyses in the study of glacial diamicts a pilot study mineral magnetic methods of characterising glacial diamicts and their associated sediments are applied to deposits within the manx quaternary sequence the possible advantages of these techniques over more traditional methods of sediment characterisation are outlined and the results obtained in a pilot study are examined results show that both distinctions and similarities exist within the magnetic mineral assemblages of the four diamict units studied the possible implications of these results for interpreting the late quaternary history of the isle of man and the future potential of the techniques are briefly discussed

characterisation of soils by mineral magnetic measurements processes of iron mineral authigenesis diagenesis and dissolution in interaction with primary inputs of iron minerals act to produce vertical differentiation of soil magnetic properties thus magnetic iron oxides in common with other iron forms may both respond to and reflect soil forming processes investigation of the degree of detectable and persistent magnetic differentiation within different soil materials can provide insights into the nature and direction of distinct sets of soil processes evidence of clear association between magnetic variation and discrete types of soil environment also has applied significance in several areas of environmental study for example the observed magnetic variation can be used to discriminate between individual soils and soil horizons for the purposes of soil surveying sediment tagging and tracing and empirical modelling of source sediment linkages this paper reports the use of mineral magnetic techniques to characterise the iron oxide assemblages within soils of varying type and provenance the effect of different pedogenic regimes have been investigated through measurement of a range of magnetic parameters including magnetic susceptibility frequency dependent susceptibility and anhysteretic and saturation remanences contrary to current pedological thought but in accord with other magnetically based studies e g mullins the presence of magnetite maghemite typically of superparamagnetic single domain grain size within soils has been found to be an extremely widespread phenomenon its contemporary neoformation within the soil environment is inferred however the input of artificially generated ferrimagnetic material is indicated for one of the magnetically enhanced soils examined here and the possibility of extraneous sources of magnetite in topsoils should be considered before pedogenic processes of magnetic enhancement are inferred from the data presented discrimination of industrially derived magnetic particles appears possible on the basis of their very low levels of frequency dependent susceptibility fd low anhysteretic remanence arm and dissociation from the finer clay sized not the formation but the active dissolution of ferrimagnetic minerals is indicated for soils affected by the processes of gleying and podsolisation eluvial horizons of podsolised profiles demonstrate almost total loss of detectable magnetic content variations in the form of the iron reprecipitated in the underlying illuvial layers may reflect differences in the pedological characteristics of these horizons within gleyed waterlogged soils processes of magnetite dissolution appear to be grain size specific preferential reduction of those grains of ultrafine superparamagnetic and fine single domain magnetic grain size is indicated where soil forms a major contributor to catchment sediment loads this has significance in the area of source sediment modelling soil derived from permanently wet or highly leached catchment areas is unlikely to contribute to peaks in the magnetic content of deposited sediments further only those erosional processes that operate at a faster rate than those of magnetic depletion will have the capacity to produce peaks in sediment ferrimagnetic concentrations such as have been observed within the historical magnetic record

glaciomarine sediments of the isle of man as a key to late pleistocene stratigraphic investigations in the irish sea basin the northern part of the isle of man in the central irish sea basin is identified as a raised marine foreland containing the largest subaerial exposure of last glaciation marine and glaciomarine sediments yet recognized on the british continental shelf a large push ridge that crosses the foreland identifies a major ice limit the ridge divides the foreland stratigraphy into a coarsening upward marine sequence of pelagic muds with dropstones sand and gravel to the south from offlapping stratified and massive sandy diamict assemblages overlying glaciotectonized marine sediments to the north coarse grained diamicts are argued to form part of a push ridge subaqueous outwash depositional system deposited when processes of suspension deposition density underflow ice rafting highly variable traction current activity and sediment gravity flow were operative adjacent to a grounded marine ice margin the identification of large offshore submarine banks aligned parallel to the bride moraine suggests that construction of the push ridge subaqueous outwash depositional system may have been repeated during ice recession this and published descriptions of other irish sea tills indicate that analogous structures and sediments are present offshore and around the irish sea basin

diagnosis of the mjo modulation of tropical cyclogenesis using an empirical index the modulation of tropical cyclone activity by the madden julian oscillation mjo is explored using an empirical genesis potential gp index composite anomalies of the genesis index associated with the different mjo phases are consistent with the composite anomalies in tc genesis frequency that occur in the same phases indicating that the index captures the changes in the environment that are at least in part responsible for the genesis frequency changes of the four environmental variables that enter the genesis potential index the midlevel relative humidity makes the largest contribution to the mjo composite gp anomalies the second largest contribution comes from the low level absolute vorticity and only very minor contributions come from the vertical wind shear and potential intensity when basin integrated mjo composite anomalies of the gp index are regressed against basin integrated composite anomalies of tc genesis frequency the results differ quantitatively from those obtained from the analogous calculation performed on the annual climatologies in the two quantities the gp index captures the mjo modulation of tc genesis to a lesser degree than the climatological annual cycle of genesis to which it was originally tuned this may be due to weaknesses of the reanalysis or indicative of the importance of precursor disturbances not well captured in the gp index computed from weekly data to the intraseasonal tc genesis frequency fluctuations

accumulation variability and mass budgets of the lambert glacier amery ice shelf system east antarctica at high elevations the temporal and spatial variability of the annual accumulation rate and the mass budgets of five sub basins of the lambert glacier amery ice shelf system las east antarctica at high elevations are assessed using a variety of datasets derived from field measurements and modeling the annual temporal variations of the accumulation rate for four cores from the west and east sides of the las are around 34 decadal fluctuation of the accumulation from the dt001 firn core drops to 10 and the 30 year fluctuation to 5 which is assumed to contain the information about the regional and long term trend in accumulation the 15 point running mean of the annual accumulation rate derived from stake measurements can remove most of the high frequency spatial variation so as to better represent the local accumulation model simulations show that the spatial variability of erosion deposition of snow by the wind has a noticeable impact on the surface mass balance at the higher parts of the las mass budget estimates at high elevation sub basins of the las suggest drainage 9 has a negative imbalance of 0 7 0 4 gt a 1 lambert and mellor glaciers have a positive imbalance of 3 9 2 1 and 2 1 2 4 gt a 1 respectively and fisher glacier and drainage 11 are approximately in balance the higher elevation region as a whole has a positive mass imbalance of 4 4 6 3 gt a 1 which is consistent with the most recent radar altimetry assessment that shows an overall thickening over this region

systematic variation of summertime tropical cyclone activity in the western north pacific in relation to the madden julian oscillation abstract the variability of observed tropical cyclone tc activity i e genesis track and landfall in the western north pacific wnp is examined in relation to the various categories of the madden julian oscillation mjo during summer june september for the period 1979 2004 the mjo categories are defined based on the empirical orthogonal function analysis of outgoing longwave radiation data the number of tcs increases when the mjo related convection center is located in the wnp the axis of a preferable genesis region systematically shifts like a seesaw in response to changes in the large scale environments associated with both the eastward and northward propagation of the mjo and the intraseasonal variability of the wnp subtropical high furthermore the authors show that the density of tc tracks in each mjo category depends on the systematic shift in the main genesis regions at first order also the shift is affected by the prevailing large scale steering flows in each mjo category when th

a multi technique study of the glacial stratigraphy of co clare and co kerry southwest ireland a multi technique approach has been adopted in a study of the lithostratigraphy of glacial deposits in southwestern ireland including clast lithological analysis fine sand geochemistry low frequency mass specific susceptibility and fine sand calcium carbonate equivalent content a revised lithostratigraphical scheme is suggested for the quaternary glacial deposits of the region together with a simple strategy that may be adopted for stratigraphical studies in other regions of southern ireland it appears that geochemical determinations via inductively coupled plasma atomic absorption spectrometry are particularly useful in characterising and discriminating between till units within local stratigraphical studies and may be used to inform the applicability of other utilitarian techniques for use on a regional scale copyright 2002 john wiley sons ltd

intensified impact of east indian ocean sst anomaly on tropical cyclone genesis frequency over the western north pacific abstracta recent finding is the significant impact of the sea surface temperature anomaly ssta over the east indian ocean eio on the genesis frequency of tropical cyclones tcs over the western north pacific wnp in this study it is shown that such an impact is significant only after the late 1970s the results based on both data analysis and numerical model experiments demonstrate that prior to the late 1970s the eio ssta is positively correlated with the equatorial central pacific ssta and the latter produces an opposite atmospheric circulation response over the wnp to the former as a result the impact of the eio ssta on the tc genesis over the wnp is largely suppressed by the latter after the late 1970s the area coverage of the eio ssta is expanding this considerably enhances the large scale circulation response over the wnp to the eio ssta and significantly intensifies the impact of the eio ssta on tc genesis frequency over the wnp the results from this study have great implications for s

modulation of eastern north pacific hurricanes by the madden julian oscillation abstract hurricane and tropical storm statistics verify the modulation of eastern pacific tropical systems by the madden julian oscillation mjo as hypothesized by maloney and hartmann over twice as many named tropical systems hurricanes and tropical storms accompany equatorial 850 mb westerly anomalies than accompany equatorial easterly anomalies and the systems that do exist are stronger hurricanes are over four times more numerous during westerly phases of the mjo than during easterly phases the current study constructs a composite life cycle of the mjo during may november 1979 95 using an index based on the 850 mb equatorial zonal wind equatorial kelvin waves propagating eastward from convective regions of the western pacific ocean alter dynamical conditions over the eastern pacific ocean westerly easterly equatorial 850 mb wind anomalies are accompanied by enhanced suppressed convection over the eastern pacific hurricane region convection locally amplifies the wind anomalies over the ea

glacial deposits at wylfa head anglesey north wales evidence for late devensian deposition in a non marine environment the nature and origin of glacial sediments at wylfa head are described and their significance with regard to sedimentary environments during late devensian deglaciation of the irish sea basin is discussed recent models of deglaciation under glaciomarine conditions are challenged the quaternary sequence at wylfa consists of eroded and glaciotectonically deformed bedrock locally derived lodgement till calcareous silt rich lodgement till containing northern erratics discontinuous units of orange brown silty sand of possible aeolian origin and grey laminated freshwater silts filling a small kettle hole the till units thicken to the south where the surface is drumlinised it is concluded that the landforms and deposits result from a warm based irish sea glacier which moved towards the southwest spatial variation in basal water pressure resulted from localised drainage through zones of more heavily jointed bedrock rapid glacial erosion occurred in areas where subglacial water pressure was relatively high while deposition of the resulting basal sediment took place where water pressures were reduced the glacier also carried basal calcareous silty till onshore which was deposited by lodgement processes none of the deposits at wylfa are interpreted as glaciomarine in origin and there is no evidence at this site for an isostatically induced marine transgression prior to deglaciation

comment and reply on glaciomarine sediments of the isle of man as a key to late pleistocene stratigraphic investigations in the irish sea basin

thickening of the western part of the greenland ice sheet nasa s program for arctic regional climate assessment parca includes measurements of ice velocity and ice thickness along the 2000 m elevation contour line in the western part of the ice sheet here we use these measurements together with published estimates of snow accumulation rates to infer the mass balance or rate of thickening thinning of the ice sheet catchment area inland from the velocity traverse within the accuracy to which we know snow accumulation rates the entire area is in balance but localized regions inland from upernavik isstrom and jakobshavn isbrae both appear to be thickening by about 10 cm a 1

primary results of glaciological studies along an 1100 km transect from zhongshan station to dome a east antarctic ice sheet the chinese national antarctic research expedition ghinare carried out three traverses from zhongshan station to dome a princess elizabeth land and inaccessible area east antarctic ice sheet during the 1996 97 to 1998 99 antarctic field seasons the expeditions are part of the chinese international trans antarctic scientific expedition program in this project glaciological investigations of mass balance ice temperature ice flow stratigraphy in snow pits and snow firn ice cores as well as the glaciochemical study of surface snow and shallow ice cores have been carried out in the 1998 99 field season chinare extended the traverse route to 1128 km inland from zhongshan station the density profiles show that firnification over princess elizabeth land and inaccessible area 290 1100 km along the route is fairly slow and the accumulation rate recovered from snow pits along the initial 460 km of the route is 4 6 21 cm 46 210 kg m 2a 1 water equivalent the initial 460 km of the route can be divided into four sections based on the differences of accumulation rate this pattern approximately coincides with the study on the lambert glacier basin lgb by australian scientists during the past 50 years the trends of both air temperature and accumulation rate show a slight increase in this area in contrast to the west side of the lgb data on surface accumulation rates and their spatial and temporal variability over ice drainage areas such as the lgb are essential for precise mass balance calculation of the whole ice sheet and are important for driving ice sheet models and testing atmospheric models

magnetic measurements of greenland and himalayan ice core samples this paper summarizes isothermal remanence irm300mt measurements from holocene ice core samples from two contrasting glaciological regimes i the greenland ice sheet and ii a himalayan glacier cores had been previously characterized in terms of chronologies geochemistry and for the himalayan core microparticle concentrations six samples from the greenland 20 d ice core from the time period ad 1876 1983 did not yield magnetic measurements above instrumental noise level significant isothermal remanence measurements irm300mt were obtained from some levels in the himalayan ice core scanning electron microscopy and edax analyses indicate weathered crustal material the techniques used require ice core samples with relatively high dust loadings and or larger volume ice samples

seasonal modulation of tropical intraseasonal oscillations on tropical cyclone geneses in the western north pacific the seasonal modulationof tropicalintraseasonal oscillation tiso on tropicalcyclone tc geneses over the western north pacific ocean wnp is investigated in three periods of the wnp tc season may june mj july september jas and october december ond the modulation of the tiso tc geneses over the wnp is strong in mj while it appears weaker in jas and ond in mj tiso propagates northward via two routes the west route through the south china sea and the east route through the wnp monsoon trough region which are two clustering locations of tc geneses tiso can synchronously influence most tc geneses overthese two regions in jas however the modulation is out of phase betweenthe monsoontrough region and the east asian summer monsoon region as well as the wnp subtropical high region as a result of further northward propagation of tiso and scattered tc geneses the tiso tc genesis modulation in each individual region is comparable to that in mj although the modulation over the entire wnp in jas appears weaker in ond tiso has a stronger influence on tc geneses west than east of 1508e because tiso decays and its convection center located at the equator is out of the tc genesis region when propagating eastward into east of 1508e midlevel relative humidity is the primary contribution to the modulations of tiso on the genesis environment while vorticity could contribute to the modulation over the subtropics in jas

modulation of hurricane activity in the gulf of mexico by the madden julian oscillation the madden julian oscillation mjo is a large scale episodic modulation of tropical winds and precipitation that travels eastward from asia to america with a characteristic repeat time of 30 to 60 days here it is shown that when mjo wind anomalies in the lower troposphere of the eastern pacific are westerly gulf of mexico and western caribbean hurricane genesis is four times more likely than when the mjo winds are easterly accurate predictions of the mjo may lead to improved long range forecasts of tropical cyclone activity

the madden julian oscillation barotropic dynamics and north pacific tropical cyclone formation part ii stochastic barotropic modeling abstract a stochastic barotropic model linearized about the 850 mb flow is used to investigate the relationship between wind variations associated with the madden julian oscillation mjo and eddy kinetic energy variations in the tropics such a model is successful in predicting the observed location of eddy kinetic energy maxima during the westerly phase of the mjo and the suppression of eddy activity during the easterly phase of the mjo the concentration of eddy energy during the westerly phase results from the strong east west and north south gradients of the large scale wind fields the model shows that barotropic wave propagation and wave mean flow interaction tend to concentrate small scale rossby wave energy in regions of convergence which may be an important mechanism for organizing convection into tropical cyclones the structure and barotropic energetics of the wave activity are similar to those observed but the modeled eddies are smaller in scale and do not move westward as do the observed e

modulation of tropical cyclogenesis location and frequency over the indo western north pacific by the intraseasonal indo western pacific convection oscillation during the boreal extended summer abstractthe influence of the intraseasonal indo western pacific convection oscillation ipco on tropical cyclone tc genesis location and frequency over the indo western north pacific wnp during the boreal extended summer may october is explored observational analysis shows that the impacts of the intraseasonal ipco on tcs over the indo wnp include an evident phase lock of tc genesis location and distinct differences in tc frequency in the wnp in the positive intraseasonal ipco phase the atmosphere gains heat through the release of latent heat in cumulus convective condensation and the anomalous cyclonic circulation weakens the western pacific subtropical high wpsh and enhances tc genesis thereby tending to produce many more tcs moreover the diminished wpsh and the westward shift of the centers of anomalous cyclonic circulations lock tc genesis locations to the west wnp and lower latitudes around 5 20 n especially in the south china sea the almost opposite situation occurs in a nega

the quaternary deposits and landforms of scotland and the neighbouring shelves a review abstract a thick sequence of quaternary sediments up to 1000 m has been deposited in the north sea basin and perhaps five major glacial episodes the first occurring prior to ca 1 8 2 1 ma bp and the last during the late devensian can be recognised between the glacial events periods of low salinity arctic marine or glacio marine sedimentation have been dominant although episodes of ameliorated climate when north atlantic drift waters had access to the north sea have been identified a number of horizons in separate boreholes have been correlated with the last interglacial oxygen isotope stage 5e and a sequence of water mass movements around the scottish coasts can be reconstructed for the last ca 125 ka on land sequences of quaternary deposits relating to several glacial and non glacial terrestrial and marine events occur in different areas but due to poor dating correlation between these sequences cannot yet be achieved in particular north east scotland has a complex glacial history with evidence for ice sheet glaciation on at least four occasions evidence from the outer hebrides north east scotland and the north sea basin indicates that the late devensian scottish ice sheet had a rather restricted extent only reaching a short distance offshore along much of the east and west coasts at this time ice free areas existed in north east scotland on the isle of lewis and probably in caithness and orkney whilst part of the outer shelf around st kilda was dry land a marine embayment extended down the east coast of scotland between the scottish and scandinavian ice sheets and independent ice caps existed on the outer hebrides and probably on shetland deglaciation of the greater part of the country took place prior to ca 13 ka bp whilst the climate was still very cold the ice retreat appears to have been orderly with stagnant ice masses being trapped only in topographically suitable locations a number of retreat stages or minor readvances occurred during the general deglaciation the firth of clyde was one of the last areas outside the highlands to be deglaciated and this occurred in a rapid possibly catastrophic fashion shortly prior to ca 13 ka bp despite the mild climate at the start of the lateglacial interstadial it is not known if there was complete deglaciation prior to the loch lomond readvance the readvance glaciers however may have started to advance during the latter part of the interstadial when declining terrestrial temperatures coincided with a period of mild marine conditions the loch lomond readvance maximum can only be dated to some time after ca 10 9 ka bp and it is likely that final ice free conditions were not achieved until the earliest holocene

holocene vegetation dynamics in the northeastern rub al khali desert arabian peninsula a phytolith pollen and carbon isotope study the holocene vegetation history of the arabian peninsula is poorly understood with few palaeobotanical studies to date at awafi ras al khaimah uae a 3 3 m lake sediment sequence records the vegetation development for the period 8500 cal yr bp to 3000 cal yr bp 13 c isotope pollen and phytolith analyses indicate that c3 pooid grassland with a strong woody element existed during the early holocene between 8500 and 6000 cal yr bp and became replaced by mixed c3 and c4 grasses with a strong c4 panicoid tall grass element between 5900 and 5400 cal yr bp an intense arid event occurred at 4100 cal yr bp when the lake desiccated and was infilled by aeolian sand from 4100 cal yr bp the vegetation was dominated by c4 chloridoid types and cyperaceae suggesting an incomplete vegetation cover and aeolian dune reactivation owing to increased regio nal aridity these data outline the ecosystem dynamics and carbon cycling in response to palaeomon soon and north westerly variability during the holocene copyright 2004 john wiley sons ltd

impact of shifting patterns of pacific ocean warming on north atlantic tropical cyclones two distinctly different forms of tropical pacific ocean warming are shown to have substantially different impacts on the frequency and tracks of north atlantic tropical cyclones the eastern pacific warming epw is identical to that of the conventional el nino whereas the central pacific warming cpw has maximum temperature anomalies located near the dateline in contrast to epw events cpw episodes are associated with a greater than average frequency and increasing landfall potential along the gulf of mexico coast and central america differences are shown to be associated with the modulation of vertical wind shear in the main development region forced by differential teleconnection patterns emanating from the pacific the cpw is more predictable than the epw potentially increasing the predictability of cyclones on seasonal time scales

the sst gradient between the southwestern pacific and the western pacific warm pool a new factor controlling the northwestern pacific tropical cyclone genesis frequency abstractthe sea surface temperature gradient sstg between the southwestern pacific ocean 40 20 s 160 e 170 w and the western pacific warm pool 0 16 n 125 165 e in boreal spring has been identified as a new factor that controls the interannual variability of tropical cyclone tc frequency over the western north pacific ocean wnp this sstg can explain 53 of the total variance of the wnp tc genesis frequency during the typhoon season for the period 1980 2011 the positive sstg anomaly produces an anomalous cross equatorial pressure gradient and thus anomalies in low level southward cross equatorial flow and tropical easterlies over the central western pacific the anomalous easterlies further produce local equatorial upwelling and seasonal cooling in the central pacific which in turn maintains the easterly anomalies throughout the typhoon season these dynamical thermodynamical effects induced by the positive sstg anomaly lead to a reduced low level cyclonic shear increased vertical wind sh

modulation of tropical cyclone tracks over the western north pacific by intra seasonal indo western pacific convection oscillation during the boreal extended summer this study investigates the effect of the intra seasonal indo western pacific convection oscillation ipco on tropical cyclone tc tracks over the western north pacific wnp during the boreal extended summer may october the number of west and northwest moving tc tracks is found to sharply increase over the wnp in the positive intra seasonal ipco phase recurving tracks have greater weight in the negative intra seasonal ipco phase possible physical mechanisms are further examined in terms of steering flow energy conversion and energy propagation when the intra seasonal ipco phase is positive the first order moment term of perturbation potential energy ppe1 converts into perturbation kinetic energy pke at lower latitudes the pressure trough spreads farther to the east meanwhile rossby waves emanating from the convective centers of the intra seasonal ipco over the wnp wavewnp and eeio waveeeio travel into the trough region thereby deepening the trough these features enhance the westward and northwestward steering flow between 20 n and about 30 n sharply increasing the number of straight west and northwest moving tc tracks over the wnp when the intra seasonal ipco is in a negative phase conversion from ppe1 to pke at lower latitudes is suppressed and the trough weakens more ppe1 converts to pke in the climatological western pacific subtropical high wpsh region and the wpsh is intensified moreover waveeeio intensifies the north south ridge of the wpsh over the southern indian peninsula meanwhile part wavewnp propagate northeastward these features favor northeastward motion of tcs over the wnp

mineral magnetic analysis of a weathering surface within glacigenic sediments at glanllynnau north wales a number of weathering horizons have been identified within glacigenic sediment sequences in north wales and have been instrumental in determining various proposed late quaternary event chronologies this paper applies the techniques of mineral magnetic analysis to such a sediment sequence at glanllynnau the presence or otherwise of evidence for weathering processes on the upper surface of the criccieth till which is overlain by further glacial materials is examined despite a marked colour variation between the weathered and non weathered components of the criccieth till their mineral magnetic properties suggest little or no variation in iron oxide assemblages the consequences of this for the environmental interpretation of the sediment sequence are discussed

effects of tropical north atlantic sst on tropical cyclone genesis in the western north pacific the tropical cyclone genesis number tcgn in july october jaso over the western north pacific wnp exhibits a robust interannual variation it shows a longitudinally tri pole pattern with a high in the eastern wnp and south china sea scs and a low in the western wnp which explain 42 2 and 23 4 of total tcgn variance in the eastern wnp and scs respectively the high low high pattern is similar to that derived from a tc genesis potential index gpi to understand the cause of the longitudinal distribution of the dominant interannual mode we examine the contributions of environmental parameters associated with gpi it is found that relative humidity and relative vorticity are important factors responsible for tc variability in the scs while vertical shear and relative vorticity are crucial in determining tc activity in eastern wnp a simultaneous correlation analysis shows that the wnp tcgn in jaso is significantly negatively correlated with a correlation coefficient of 0 5 with sea surface temperature anomalies ssta in the tropical north atlantic tna the longitudinal distribution of tc genesis frequency regressed onto tna ssta resembles that regressed upon the wnp tcgn series the spatial patterns of regressed environmental variables onto the ssta over the tna also resemble those onto tcgn in the wnp that is an increase of relative humidity in the scs and a weakening of vertical shear in the eastern wnp are all associated with cold ssta in the tna further analyses show that the cold ssta in the tna induce a negative heating in situ in response to this negative heating a low upper level anomalous aniti cyclonic cyclonic flows appear over the subtropical north atlantic and eastern north pacific and to east of the cold ssta anomalous low level westerlies appear in the tropical indian ocean given pronounced mean westerlies in northern indian ocean in boreal summer the anomalous westerly flows increase local surface wind speed and surface evaporation and cool the sst in situ cold ssta in northern indian ocean further suppress local convection inducing anomalous westerlies to its east leading to enhanced cyclonic vorticity and low surface pressure over the wnp monsoon trough region idealized numerical experiments further confirm this indian ocean relaying effect through which cold ssta in the tropical atlantic exert a remote impact to circulation in the wnp

interhemispheric influence of indo pacific convection oscillation on southern hemisphere rainfall through southward propagation of rossby waves tropical indo western pacific convection anomalies influence atmospheric circulation impacting climate far beyond the tropics here we present observational and modelling evidence for an interhemispheric effect of the boreal summer june august indo pacific convection oscillation ipco which is characterized by a zonal seesaw pattern between the north indian ocean nio and the western north pacific wnp it is found that the ipco is significantly correlated with simultaneous rainfall over many parts of the southern hemisphere sh including western australia and western brazil these interhemispheric connections in rainfall remain significant when then el nino southern oscillation the indian ocean dipole and the sh annular mode related signals are excluded simultaneously which may help to improve the sh seasonal predictions the physical mechanism that underlies this interhemispheric connection is investigated using observations rossby wave diagnostics and a series of atmospheric model experiments results suggest that convective heating anomalies associated with the ipco excite two distinct southward propagating equivalent barotropic wave trains that propagate into the extratropics in the sh the south africa mid latitudes wave train excited by the heat sink over the nio and the maritime continent subtropical australia wave train excited by the heat source over the wnp we further demonstrate that upper tropospheric northerlies over tropical africa and the indian ocean are responsible for the southward propagation of stationary rossby waves across the easterlies these equivalent barotropic waves then modulate the moisture transport baroclinicity and mid latitude storminess and thus affect rainfall anomalies in the sh the new wave train patterns provide novel insight into the teleconnection pathways of convective heating over the tropical indian ocean and western pacific

an anomalous genesis potential index for mjo modulation of tropical cyclones abstractmodulation of tropical cyclone tc genesis by the madden julian oscillation mjo has been quantitatively diagnosed by using a climatological genesis potential index gpi analysis of tc genesis during november april of 1979 2014 indicates the most effective factors controlling intraseasonal tc genesis are 850 hpa relative vorticity weighted by the coriolis parameter f r850 and 500 hpa vertical motion 500 the total vertical wind shear and maximum potential intensity are unimportant and the role of 600 hpa relative humidity is greatly represented by 500 the mjo modulates tc genesis primarily through changing low level vorticity induced by its rossby wave gyres and meridional shears of equatorial zonal winds a new intraseasonal gpi isgpi is proposed to quantify the mjo s modulation of tc genesis the isgpi significantly improves representation of intraseasonal variation of tc genesis in the tropics and in each subregion of the southern indian ocean australian monsoon and south pacific i

the 30 60 day convection seesaw between the tropical indian and western pacific oceans abstract the tropical indian and western pacific oceans are two prominent action centers for tropical 30 60 day convective variability when convection is enhanced over the equatorial indian ocean the tropical western pacific often experiences an abnormal dry condition phase i whereas the development of the convection over the tropical western pacific tends to be accompanied by suppressed convection in the equatorial indian ocean phase ii this convection seesaw is a fundamental characteristic of the tropical 30 60 day oscillation the seesaw is intimately associated with the activity of propagating low frequency convective systems lfcss its formation process is season dependent typical boreal summer seesaw results from a time lagged development of two systems a western system that originates in the equatorial indian ocean and moves eastward and or northward and an eastern system that develops in the western pacific monsoon region and moves westward and or northward the boreal winter seesaw o

impact of the quasi biweekly oscillation on the super typhoon tracks in winter over the western north pacific this study investigates the tracks of category 4 and 5 typhoons tys in the western north pacific wnp in november december during 1979 2016 and their relationships with the intraseasonal oscillation iso including the 30 60 day and 12 25 day variations it is shown that the impact of iso on the ty tracks found in previous studies is mainly contributed by the quasi biweekly oscillation qbwo the impact on the ty tracks is through influence on the steering flows over the wnp accordingly tys are separated into two types moving westward tyw and northeastward tye qbwo in the wnp is associated with an active convection originated from the equatorial wnp which propagates northwestward and reaches the scs and middle high latitudes tyw mostly occurs in the decline stage of the qbwo life cycle while tye appears in the mature stage of qbwo for tyw qbwo hardly changes the background large scale circulation which features an anticyclonic circulation covering the entire wnp and scs thus tyw moves westward however tye appears in the mature phase of qbwo the strong convection induces an intense cyclonic circulation in western part of the wnp thus changes the steering flow the steering flow features an anticyclonic circulation over the mid eastern wnp which is favorable for tye to divert the direction and move northeastward

artificial magnetic enhancement of stream bedload a hydrological application of superparamagnetism abstract laboratory heat treatment of natural rocks alters their mineralogy and produces a characteristic magnetization that can be used as a simple persistent tracer workers have shown that natural magnetic enhancements occur in soils on a wide range of bedrocks including limestones granites shales and sandstones the artificial magnetic enhancement tracing method may consequently be expected to be applicable to many localities in our study magnetite and hematite were grown in naturally paramagnetic mudstones and slates by rapid heating in air to 900 c and then quenching studies of magnetic remanence viscosity hysteresis and coercivity m ssbauer spectroscopy and the effect of temperature on magnetization have been used to determine the dominant processes affecting the magnetic mineralogy during heat treatment these are the growth of single domain magnetite followed by the formation of superparamagnetic magnetite probably by both the breakdown of the single domain magnetite and the growth of new crystals simultaneously with the formation of hematite the fine magnetite particles dominate most of the magnetic properties of the heat treated samples although hematite is produced in greater abundance the mineralogical changes of the magnetic grains are complex and depend on many interrelated variables however a very simple but effective heat treatment procedure has been developed that optimizes the enhancement of magnetic susceptibility and permits practical hydrological field experiments to be performed this work is concerned with stream bedload movement but the artificial magnetic enhancement method could also be useful in studying other sedimentological processes such as movement of sand waves and beach sands and the silting of harbours

interdecadal variability of western north pacific tropical cyclone tracks abstract this study examines the interdecadal variability of the tropical cyclone tc tracks over the western north pacific wnp during the 1960 2005 period an empirical orthogonal function analysis of the 10 yr gaussian filtered annual frequency of tc occurrence shows three leading modes of tc occurrence patterns the first mode is related to the variation of tc activity in the areas near japan and its east the second mode is characterized by a northeast southwest dipole of tc occurrence anomalies along the southeast coast of china and an east west dipole near japan and its east the third mode is similar to the second mode except for the absence of the east west dipole these patterns are shown to be related to the decadal changes in the prevailing tc tracks two characteristic flow patterns related to the first and third modes of tc occurrence pattern are identified the first pattern is characterized by a north south dipole of 500 hpa geopotential anomalies over the wnp such a pattern may affect

equatorial windows and barriers for stationary rossby wave propagation abstractrossby waves can cross the equator and connect the northern hemisphere nh and southern hemisphere sh or be blocked in the vicinity of the equator this work explores the windows and ba