the response of the southwest western australian wave climate to indian ocean climate variability knowledge of regional wave climates is critical for coastal planning management and protection in order to develop a regional wave climate it is important to understand the atmospheric systems responsible for wave generation this study examines the variability of the southwest western australian swwa shelf and nearshore wind wave climate and its relationship to southern hemisphere climate variability represented by various atmospheric indices the southern oscillation index soi the southern annular mode sam the indian ocean dipole mode index dmi the indian ocean subtropical dipole iosd the latitudinal position of the subtropical high pressure ridge strp and the corresponding intensity of the subtropical ridge stri a 21 year wave hindcast 1994 2014 of the swwa continental shelf was created using the third generation wave model simulating waves nearshore swan to analyse the seasonal and inter annual wave climate variability and its relationship to the atmospheric regime strong relationships between wave heights and the strp and the stri a moderate correlation between the wave climate and the sam and no significant correlation between soi dmi and iosd and the wave climate were found strong spatial seasonal and inter annual variability as well as seasonal longer term trends in the mean wave climate were studied and linked to the latitudinal changes in the subtropical high pressure ridge and the southern ocean storm belt as the southern ocean storm belt and the subtropical high pressure ridge shifted southward northward wave heights on the swwa shelf region decreased increased the wave height anomalies appear to be driven by the same atmospheric conditions that influence rainfall variability in swwa

tectonic implications of paleomagnetic and geochronologic data from the yukon koyukuk province alaska the paleomagnetic and geochronologic record of alaska is complicated by overprints that make it difficult to relate the terranes of northern and southern alaska to each other and to north america to better understand these relationships and the overprinting paleomagnetic and k ar dating samples were analyzed from the three major geologic units of the yukon koyukuk province ykp of central alaska these units consist of a basal jurassic early cretaceous volcanic island arc assemblage albian cenomanian clastic sedimentary rocks and bimodal eocene volcanic rocks k ar age determinations of the early tertiary volcanic rocks form two distinct groups the older group 65 49 ma is mostly felsic and probably represents the maximum inboard penetration of low angle subduction related volcanism these older rocks were deformed during the regional deformation of the ykp the younger group 44 43 ma is post deformational and composed dominantly of basalt these results bracket a time 49 44 ma when deformation ceased in the province this time interval is coincident with a major transition from convergence to strike slip and extensional tectonic style throughout alaska the geologic units of the ykp display two characteristic paleomagnetic signatures primary directions based on positive reversal conglomerate and or bedding tilt stability tests were obtained from the albian cenomanian sedimentary rocks and eocene volcanic rocks the mid cretaceous sedimentary rocks show about 15 of poleward motion between 90 56 ma a time of high rates of convergence between alaska and the pacific and eurasian plates age equivalent rocks from neighboring regions st matthew island and the alaskan north slope also indicate similar amounts of poleward northward motion which suggests that the whole of western and northern alaska may have moved northward about 10 relative to north america as a more or less coherent block paleomagnetic results from the eocene volcanic rocks indicate that the ykp was in place by 56 ma and formed part of the accretionary nucleus that served as a backstop for the accreted terranes of southern alaska secondary remagnetized directions are recorded in the basal island arc assemblage and in albian cenomanian sediments near younger igneous occurrences the clustering of secondary directions in the geographic reference frame indicates that they were acquired after deformation ceased 49 44 ma which is consistent with the coincidence of the mean of these directions and the 54 44 ma north american reference direction

zonal asymmetry of the antarctic oscillation 1 in this research the zonal asymmetry of the southern annular mode or the antarctic oscillation aao is studied it is indicated that apparent zonal asymmetry exists in the normalized sea level pressure differences between the middle and high latitudes during the boreal summer among different longitudes especially between the western and eastern hemispheres results show that the southern oscillation so is responsible for part of the zonal asymmetry in aao the western hemisphere and the eastern hemisphere parts of aao are correlated at 0 23 and 0 52 respectively for the period of 1959 1998 before and after the linear regressions on the southern oscillation index soi have been removed from the time series the paper also discusses the relationship between the precipitation in the east asia and the aao before and after removing the linear regressions on so index soi indicating the stable relationship between the east asian precipitation and the zonal symmetric component of aao

spatial patterns of variability in antarctic surface temperature connections to the southern hemisphere annular mode and the southern oscillation 1 the 17 year 1982 1998 trend in surface temperature shows a general cooling over the antarctic continent warming of the sea ice zone with moderate changes over the oceans warming of the peripheral seas is associated with negative trends in the regional sea ice extent effects of the southern hemisphere annular mode sam and the extrapolar southern oscillation so on surface temperature are quantified through regression analysis positive polarities of the sam are associated with cold anomalies over most of antarctica with the most notable exception of the antarctic peninsula positive temperature anomalies and ice edge retreat in the pacific sector are associated with el nino episodes over the past two decades the drift towards high polarity in the sam and negative polarity in the so indices couple to produce a spatial pattern with warmer temperatures in the antarctic peninsula and peripheral seas and cooler temperatures over much of east antarctica

a predominant reversal in the relationship between the sam and east antarctic temperatures during the twenty first century abstractthe scientific literature portrays a temporally invariant spatial relationship between the phase of the southern annular mode sam and the sign of surface air temperature sat anomalies across antarctica however here the authors describe a predominant switch from a negative to positive sam temperature relationship str across east antarctica in austral summer autumn during the first decade of the twenty first century when the sam was generally weakly positive of the nine years that had a positive regional str from 1957 to 2010 seven occurred during the last decade this reversal appears to be a response to anomalous high pressure over east antarctica resulting from variability in the phase and amplitude of the local component of the zonal wavenumber 3 pressure pattern in years when a reversed positive regional str exists the anomalous circulation is such that there is greater energy flux into the region while enhanced katabatic drainage across the continental interior disrupts the sur

a recent sea ice retreat west of the antarctic peninsula satellite passive microwave data show a record decrease in sea ice extent in the bellingshausen sea from mid 1988 through early 1991 the change coincides with more southerly surface winds increased cyclonic activity and rising surface air temperatures which reached historic highs along the west coast of the antarctic peninsula in 1989 preceded by high ice cover in 1986 87 the retreat was most evident during summer in the formerly perennial sea ice field over the continental shelf ocean heat storage probably contributed to the persistence and coastal propagation of this anomaly

teleconnections between tropical pacific sst anomalies and extratropical southern hemisphere climate abstractteleconnections from tropical pacific sea surface temperature sst anomalies to the high latitude southern hemisphere sh are examined using observations and reanalysis analysis of tropical pacific sst anomalies is conducted separately for the central pacific cp and eastern pacific ep regions during the austral cold season extratropical sh atmospheric rossby wave train patterns are observed in association with both ep and cp sst variability the primary difference between the patterns is the westward displacement of the cp related atmospheric anomalies consistent with the westward elongation of cp related convective sst required for upper level divergence and rossby wave generation consequently cp related patterns of sh sst antarctic sea ice and temperature anomalies also exhibit a westward displacement but otherwise the cold season extratropical sh teleconnections are largely similar during the warm season however extratropical sh teleconnections associated with tropical cp and

annular modes in the extratropical circulation part i month to month variability the leading modes of variability of the extratropical circulation in both hemispheres are characterized by deep zonally symmetric or annular structures with geopotential height perturbations of opposing signs in the polar cap region and in the surrounding zonal ring centered near 458 latitude the structure and dynamics of the southern hemisphere sh annular mode have been extensively documented whereas the existence of a northern hemisphere nh mode herein referred to as the arctic oscillation ao has only recently been recognized like the sh mode the ao can be defined as the leading empirical orthogonal function of the sea level pressure field or of the zonally symmetric geopotential height or zonal wind fields in this paper the structure and seasonality of the nh and sh modes are compared based on data from the national centers for environmental prediction national center for atmospheric research reanalysis and supplementary datasets the structures of the nh and sh annular modes are shown to be remarkably similar not only in the zonally averaged geopotential height and zonal wind fields but in the mean meridional circulations as well both exist year round in the troposphere but they amplify with height upward into the stratosphere during those seasons in which the strength of the zonal flow is conducive to strong planetary wave mean flow interaction midwinter in the nh and late spring in the sh during these active seasons the annular modes modulate the strength of the lagrangian mean circulation in the lower stratosphere total column ozone and tropopause height over mid and high latitudes and the strength of the trade winds of their respective hemispheres the nh mode also contains an embedded planetary wave signature with expressions in surface air temperature precipitation total column ozone and tropopause height it is argued that the horizontal temperature advection by the perturbed zonal mean zonal wind field in the lower troposphere is instrumental in forcing this pattern a companion paper documents the striking resemblance between the structure of the annular modes and observed climate trends over the past few decades

modeling the impact of wind intensification on antarctic sea ice volume abstracta global sea ice ocean model is used to examine the impact of wind intensification on antarctic sea ice volume based on the ncep ncar reanalysis data there are increases in surface wind speed 0 13 yr 1 and convergence 0 66 yr 1 over the ice covered areas of the southern ocean during the period 1979 2010 driven by the intensifying winds the model simulates an increase in sea ice speed convergence and shear deformation rate which produces an increase in ridge ice production in the southern ocean 1 1 yr 1 the increased ridged ice production is mostly in the weddell bellingshausen amundsen and ross seas where an increase in wind convergence dominates the increase in ridging production contributes to an increase in the volume of thick ice thickness 2 m in the southern ocean while the volumes of thin ice thickness 1 m and medium thick ice 1 m thickness 2 m remain unchanged over the period 1979 2010 the increase in thick ice leads to an increase in ice volume in the s

ice core evidence for significant 100 year regional warming on the antarctic peninsula we present a new 150 year high resolution stable isotope record delta o 18 from the gomez ice core drilled on the data sparse south western antarctic peninsula revealing a similar to 2 7 degrees c rise in surface temperatures since the 1950s the record is highly correlated with satellite derived temperature reconstructions and instrumental records from faraday station on the north west coast thus making it a robust proxy for local and regional temperatures since the 1850s we conclude that the exceptional 50 year warming previously only observed in the northern peninsula is not just a local phenomena but part of a statistically significant 100 year regional warming trend that began around 1900 a suite of coupled climate models are employed to demonstrate that the 50 and 100 year temperature trends are outside of the expected range of variability from pre industrial control runs indicating that the warming is likely the result of external climate forcing citation thomas e r p f dennis t j bracegirdle and c franzke 2009 ice core evidence for significant 100 year regional warming on the antarctic peninsula geophys res lett 36 l20704 doi 10 1029 2009gl040104

holocene glacial activity in barilari bay west antarctic peninsula tracked by magnetic mineral assemblages linking ice ocean and atmosphere we investigate the origin and fate of lithogenic sediments using magnetic mineral assemblages in barilari bay west antarctic peninsula ap from sediment cores recovered during the larsen ice shelf system antarctica larissa nbp10 01 cruise to quantify and reconstruct holocene changes in co varying magnetic mineral assemblages we adopt an unsupervised mathematical un mixing strategy and apply it to measurements of magnetic susceptibility as a function of increasing temperature comparisons of the unmixed end members with magnetic observations of northwestern ap bedrock and the spatial distribution of magnetic mineral assemblages within the fjord allow us to identify source regions including signatures for inner bay outer bay and northwestern ap sources we find strong evidence that supports the establishment of a late holocene ice shelf in the fjord coeval with the little ice age additionally we present new evidence for late holocene sensitivity to conditions akin to positive mean southern annual mode states for western ap glaciers at their advanced neoglacial positions this article is protected by copyright all rights reserved

the relationship between the southern hemisphere annular mode and antarctic peninsula summer temperatures analysis of a high resolution model climatology abstract the large regional summer warming on the east coast of the northern antarctic peninsula ap which has taken place since the mid 1960s has previously been proposed to be caused by a trend in the southern hemisphere annular mode sam the authors utilize a high resolution regional atmospheric model climatology 14 km grid spacing to study the mechanisms that determine the response of the near surface temperature to an increase in the sam t sam month to month variations in near surface temperature and surface pressure are well represented by the model it is found that north of 68 s t sam is much larger on the eastern lee side than on the western windward side of the barrier this is because of the enhanced westerly flow of relatively warm air over the barrier which warms and dries further as it descends down the lee slope the downward motion on the eastern side of the barrier causes a decrease in surface mass balance and cloud cover south of 68 s vertical deflection across

strong surface melting preceded collapse of antarctic peninsula ice shelf 1 during the austral summer of 2001 02 melting at the surface of larsen ice shelf in the antarctic peninsula was three times greater than the average of five previous summers this exceptional melt event lasted for three months and was followed by the collapse of larsen b ice shelf during which 3 200 km2 of ice shelf surface was lost the strong melting was caused by a persistent atmospheric circulation anomaly which depleted sea ice concentrations in front of larsen ice shelf and transported warm air to the ice shelf throughout the 2001 02 summer this supports the theory that large meltwater fluxes accelerate the retreat of antarctic peninsula ice shelves

the characteristic variability and connection to the underlying synoptic activity of the amundsen bellingshausen seas low 1 recent studies have noted an asymmetrical climate change across antarctica with significant warming in west antarctica and the antarctica peninsula and primarily insignificant trends in east antarctica due to its proximity variations in the position and intensity of the amundsen bellingshausen seas low absl are a suspected atmospheric mechanism here we investigate the absl to understand its characteristic variability and underlying synoptic scale influences based on three reanalysis data sets the absl is defined as the minimum monthly pressure in the 45 75 s 180 60 w domain using this criterion a significant north south and east west progression is noted in the climatological 1979 2001 average absl which is strongly tied to the location of the maximum cyclone system density and minimum cyclone central pressures more than 550 cyclones a year were identified in the vicinity of the absl during spring significant trends in their central pressures are noted in the ross sea the implied changes in temperature advection by these stronger systems are consistent with the warming in west antarctica the strongest cyclone events i e the ten with the deepest central pressures also demonstrate a connection to the climatological absl albeit weaker moreover these strong cyclone events are significantly linked to the southern annular mode sam particularly in their annual frequency and location steering in the summer this shows that large scale forcing such as from the sam may influence the strongest cyclones in the region and could allow for the prediction of such events

foehn winds link climate driven warming to ice shelf evolution in antarctica rapid warming of the antarctic peninsula over the past several decades has led to extensive surface melting on its eastern side and the disintegration of the prince gustav larsen a and larsen b ice shelves the warming trend has been attributed to strengthening of circumpolar westerlies resulting from a positive trend in the southern annular mode sam which is thought to promote more frequent warm dry downsloping foehn winds along the lee or eastern side of the peninsula we examined variability in foehn frequency and its relationship to temperature and patterns of synoptic scale circulation using a multidecadal meteorological record from the argentine station matienzo located between the larsen a and b embayments this record was further augmented with a network of six weather stations installed under the u s nsf larsen ice shelf system antarctica project significant warming was observed in all seasons at matienzo with the largest seasonal increase occurring in austral winter 3 71 c between 1962 1972 and 1999 2010 frequency and duration of foehn events were found to strongly influence regional temperature variability over hourly to seasonal time scales surface temperature and foehn winds were also sensitive to climate variability with both variables exhibiting strong positive correlations with the sam index concomitant positive trends in foehn frequency temperature and sam are present during austral summer with sustained foehn events consistently associated with surface melting across the ice sheet and ice shelves these observations support the notion that increased foehn frequency played a critical role in precipitating the collapse of the larsen b ice shelf

observations of change in the southern ocean the southern ocean has been in a state of disequilibrium with its atmosphere and cryosphere during recent decades ocean station and drifting float observations have revealed rising temperatures in

glaciological and climatic significance of hercules dome antarctica an optimal site for deep ice core drilling 1 we present glaciological and climatological characteristics of hercules dome antarctica 86 s 105 w which demonstrate its potential as a deep ice core site annual layering in d ratios from a 72 m ice core collected by the us itase 2002 traverse indicate accumulation rates of 0 16 0 20 m yr ice equivalent over the last 300 years age control from stratigraphy seen in the radio echo sounding data collected during the same traverse suggests a rate of 0 09 0 11 m yr averaged over the past 18 000 years ice stratigraphy also indicates that the ice divide position has been stable through at least this period comparison of satellite derived temperature anomalies with atmospheric reanalysis data show that the site is sensitive to the two dominant patterns of climate variability in the high latitude southern hemisphere climate proxy data from a deep ice core at hercules dome would be indicative of changes in pacific southern hemisphere climate variability and may provide new information on rapid climate change events in antarctica the sensitivity of the site and the combination of relatively high accumulation rates low temperatures mean annual 35 c to 40 c and simple ice flow suggest that hercules dome is an ideal site for a future deep ice core

analysis of the projected regional sea ice changes in the southern ocean during the twenty first century using the set of simulations performed with atmosphere ocean general circulation models aogcms for the fourth assessment report of the intergovernmental panel on climate change ipcc ar4 the projected regional distribution of sea ice for the twenty first century has been investigated averaged over all those model simulations the current climate is reasonably well reproduced however this averaging procedure hides the errors from individual models over the twentieth century the multimodel average simulates a larger sea ice concentration decrease around the antarctic peninsula compared to other regions which is in qualitative agreement with observations this is likely related to the positive trend in the southern annular mode sam index over the twentieth century in both observations and in the multimodel average despite the simulated positive future trend in sam such a regional feature around the antarctic peninsula is absent in the projected sea ice change for the end of the twenty first century the maximum decrease is indeed located over the central weddell sea and the amundsen bellingshausen seas in most models changes in the oceanic currents could play a role in the regional distribution of the sea ice especially in the ross sea where stronger southward currents could be responsible for a smaller sea ice decrease during the twenty first century finally changes in the mixed layer depth can be found in some models inducing locally strong changes in the sea ice concentration

climate change in the western antarctic peninsula since 1945 observations and possible causes temperature records from stations on the west coast of the antarctic peninsula show a very high level of interannual variability and over the last 50 years larger warming trends than are seen elsewhere in antarctica in this paper we investigate the role of atmospheric circulation variability and sea ice extent variations in driving these changes owing to a lack of independent data the reliability of antarctic atmospheric analyses produced in the 1950s and 1960s cannot be readily established but examination of the available data suggests that there has been an increase in the northerly component of the circulation over the peninsula since the late 1950s few observations of sea ice extent are available prior to 1973 but the limited data available indicate that the ice edge to the west of the peninsula lay to the north of recently observed extremes during the very cold conditions prevailing in the late 1950s the ultimate cause of the atmospheric circulation changes remains to be determined and may lie outside the antarctic region

a century of climate variability in central dronning maud land east antarctica and its relation to southern annular mode and el nino southern oscillation stable isotope records of oxygen and hydrogen were studied from a 65 m long ice core retrieved from the central dronning maud land east antarctica in order to reconstruct the coastal antarctic climate variability during the last century and its relation to the southern annular mode sam and el nino southern oscillation enso the 18 o records showed a significant relation to the sam with a dominant 4 years variability except during specific periods 1918 1927 19381947 1989 2005 when enso teleconnection was established through the in phase relation between sam and southern oscillation index soi the combined influence of enso and sam was seen on surface air temperatures in this region mainly during the austral summer season from 1989 to 2005 further a significant relationship between 18 o and sam was observed on a decadal scale which overrides the intermittent influence of enso major shifts in the deuterium excess record were observed during periods of enso teleconnections which support a shift in moisture source regions during the periods of stronger enso teleconnections surface air temperatures estimated using the 18 o t spatial slope for this region depicted a significant warming of 1 c for the past century the study reveals that throughout the last century sam was the dominant mode of climatic variability in the coastal region of central dronning maud land on a decadal scale

central west antarctica among the most rapidly warming regions on earth the west antarctic ice sheet is contributing to sea level rise but temperature trends in the region have remained uncertain a complete temperature record for byrd station in central west antarctica spanning from 1958 to 2010 establishes west antarctica as one of the fastest warming regions globally

an analysis of the atmospheric processes driving the large scale winter sea ice variability in the southern ocean the response of the sea ice in the southern ocean to the variability of the atmosphere on the period 1979 2004 is investigated using both model and observational data on the one hand our results show that in line with previous investigations the classical modes of atmospheric variability do not explain a large part of the winter sea ice extent variability integrated over the entire southern ocean on the other hand the regression between the ice extent and the atmospheric pressure displays a pattern with low pressure areas over the south atlantic over the indian ocean and on the southwestern part of the pacific ocean and a high pressure area over the antarctic region extending toward both the southeastern pacific and the region south of australia this pattern which does not correlate significantly with any of the known modes of atmospheric variability induces changes in the sea ice extent by influencing the air temperature the ice production and both the meridional and the zonal ice velocity however there is no clear link between the different centers of action of this pattern furthermore the correlation of the sea ice extent between the different sectors is generally low as a conclusion we must consider that the sea ice extent in the southern ocean over the last 30 years does not behave as a single entity its variability is the result of the combination of regional sea ice changes each sector should thus be examined separately

processes controlling upper ocean heat content in drake passage 1 a 16 year record of expendable bathythermograph transects across drake passage is used to examine variability in upper ocean heat content that is not associated with the annual cycle links between upper ocean heat content and anomalous heat fluxes winds two large scale climate indices and mesoscale eddies and meanders are examined results suggest that interannual variations in surface heat fluxes explain 5 to 10 of the variance in upper ocean heat content anomalous surface heat fluxes are linked to meridional wind anomalies upstream of drake passage which in turn are linked to forcing by el nino southern oscillation enso and the southern annular mode sam enso and sam are correlated with upper ocean heat content at near zero lags and statistically significant correlations occur at longer time lags as well the impact of mesoscale eddies and meanders on upper ocean heat content is explored with the use of a tracked eddy database an empirical relationship is constructed relating upper ocean heat content anomalies to eddy length scales and amplitudes eddies and meanders are estimated to account for more than one third of the nonannual cycle variance in drake passage upper ocean heat content

characteristics of summer airflow over the antarctic peninsula in response to recent strengthening of westerly circumpolar winds abstract summer near surface temperatures over the northeast coast of the antarctic peninsula have increased by more than 2 c over the past 40 years a temperature increase 3 times greater than that on the northwest coast recent analysis has shown a strong correlation between this striking warming trend and significant change in the summer southern hemisphere annular mode sam which has resulted in greatly increased summer westerlies across the northern peninsula it has been proposed that the strengthening westerlies have resulted in increased vertical deflection of relatively warm maritime air over the northern peninsula contributing significantly to the observed warming and the recent collapse of northern sections of the larsen ice shelf in this study laboratory and numerical modeling of airflow incident to the peninsula are employed to further understand this mechanism it is shown that the effect of the strengthening westerlies has led to a distinct transition from a blocked regime to a flow

linked trends in the south pacific sea ice edge and southern oscillation index previous work have shown that sea ice variability in the south pacific is associated with extratropical atmospheric anomalies linked to the southern oscillation so over a 32 year period 1982 2013 our study shows that the trend in southern oscillation index soi is also able to quantitatively explain the trends in sea ice edge drift and surface winds in this region on average two thirds of the winter ice edge trend in this sector linked to ice drift and surface winds could be explained by the positive soi trend thus subjecting the ice edge to strong decadal so variability if this relationship holds the negative soi trend prior to the recent satellite era suggests that ice edge trends opposite to that of the recent record over a similar time scale significant low frequency ice edge trends linked to the natural variability of so are superimposed upon any trends expected of anthropogenic forcing

recent atmospheric warming and retreat of ice shelves on the antarctic peninsula in 1978 mercer1 discussed the probable effects of climate warming on the antarctic ice sheet predicting that one sign of a warming trend in this region would be the retreat of ice shelves on the antarctic peninsula analyses of 50 year meteorological records have since revealed atmospheric warming on the antarctic peninsula2 3 and a number of ice shelves have retreated4 8 here we present time series of observations of the areal extent of nine ice shelves on the antarctic peninsula showing that five northerly ones have retreated dramatically in the past fifty years while those further south show no clear trend comparison with airtemperature data shows that the pattern and magnitude of ice shelf retreat is consistent with the existence of an abrupt thermal limit on iceshelf viability the isotherm associated with this limit having been driven south by the atmospheric warming ice shelves therefore appear to be sensitive indicators of climate change

hydrographic survey in the dying aral sea 1 we report the results of a hydrographic survey conducted in november 2002 in the uzbekistan part of the western basin of the dying aral sea there were very few hydrographic measurements in this region since at least early 1990s the salinity in the western deep basin of the aral sea varied from about 82 psu at the surface to over 94 psu at the bottom the absolute lake surface level was about 30 5 m hence the observed salinity values were much higher and the level much lower than expected according to earlier predictions the density in the western basin exhibited an extremely strong stratification of 11 kg m3 per 20 m in the bottom layer the picnocline was accompanied by a temperature inversion whose magnitude was 4 c the observed density stratification effectively isolating the lower part of the water column from surface exchanges may be responsible for the increase of summer ssts and evaporation rates reported in previous studies we discovered the hydrogen sulphide contamination in the bottom layer whose upper limit was at the depth of approximately 22 m estimates suggest that the western basin salinization occurs not only because of the local evaporation but also because of the assimilation of the saltier eastern basin water in the course of the interbasin exchange through the connecting channel the satellite imagery analysis in particular the maximum cross correlation method suggests that the circulation pattern in the aral sea in its present limits is cyclonic under the eastern winds that are predominant in the region throughout the year

changma onset definition in korea using the available water resources index and its relation to the antarctic oscillation this study defines the changma onset using the available water resources index awri for 25 years 1985 2009 and verifies the validity of this definition the three conditions for defining the changma onset are established as follows i the first day exceeding the june awri threshold averaged over the 25 year period ii the continuation of the value over the threshold for at least 1 week after the onset iii after the continuation of more than 1 week the non continuation of the value under the threshold for at least 1 week the 25 year average changma onset date is 24 june with a standard deviation of 9 days the defined changma onset is verified through the analysis on the relationship with the antarctic oscillation aao aao in june shows a high correlation with not only the changma onset but also the june precipitation awri in korea these three variables are influenced by mascarene and australian positive aao pattern highs from in the preceding march when these two pressure systems develop the cold cross equatorial flow in the direction from the region around australia to the equator is intensified which in turn forces a western north pacific high wnph to develop northward this eventually drives the rain belt north as a result the changma begins early in the positive aao phase and the june precipitation increases in korea in addition a wnph that develops more northward increases the landfalling frequency of tropical cyclones in korea which plays an important role in increasing the june precipitation

climate variability in the amundsen and bellingshausen seas satellite data reveal a 20 decline in sea ice extent in the amundsen and bellingshausen seas in the two decades following 1973 this change is negatively correlated with surface air temperatures on the west side of the antarctic peninsula which have increased 0 58c decade21 since the mid 1940s the recession was strongest during summer when monthly average minima in 1991 92 removed much of the incipient multiyear ice over the continental shelf this would have lowered the regional mean ice thickness impacting snow ice formation brine production and vertical heat flux the northern ice edge contracted by 18 of latitude in all seasons from 1973 79 to 1987 93 returning toward mean conditions in 1993 95 the decline included multiyear cycles of several years in length superimposed on high interannual variability a review of atmospheric forcing shows winds consistent with mean and extreme ice extents and suggests links to larger scale circulation changes in the south pacific historical ocean measurements are sparse in this sector but mixed layer depths and upper pycnoclines beneath the sea ice resemble those in the weddell sea weaker surface currents or changes in the upwelling of circumpolar deep water on the continental shelf could have contributed to the anomaly persistence

understanding the sam influence on the south pacific enso teleconnection the relationship between the el nino southern oscillation enso and the southern hemisphere annular mode sam is examined with the goal of understanding how various strong sam events modulate the enso teleconnection to the south pacific 45 70 s 150 70 w the focus is on multi month multi event variations during the last 50 years a significant p 0 10 relationship is observed most marked during the austral summer and in the 1970s and 1990s in most cases the significant relationship is brought about by la nina el nino events occurring with positive negative phases of the sam more often than expected by chance the south pacific teleconnection magnitude is found to be strongly dependent on the sam phase only when enso events occur with a weak sam or when a la nina el nino occurs with a positive negative sam phase are significant south pacific teleconnections found this modulation in the south pacific enso teleconnection is directly tied to the interaction of the anomalous enso and sam transient eddy momentum fluxes during la nina sam and el nino sam combinations the anomalous transient momentum fluxes in the pacific act to reinforce the circulation anomalies in the midlatitudes altering the circulation in such a way to maintain the enso teleconnections in la nina sam and el nino sam cases the anomalous transient eddies oppose each other in the midlatitudes overall acting to reduce the magnitude of the high latitude enso teleconnection

synoptic variability in the ross sea region antarctica as seen from back trajectory modeling and ice core analysis 1 synoptic variability in the ross sea region antarctica over the last thirty years is investigated using back trajectory modeling and cluster analysis we identify two dominant air mass trajectory clusters oceanic west antarctic and continental east antarctic our analysis shows that the oceanic west antarctic trajectories have an annual cycle similar to the semiannual oscillation and on average peak in frequency during april while continental east antarctic trajectories reach their annual maximum during december we demonstrate a causal association between the el nino southern oscillation enso and the frequency of oceanic west antarctic trajectories originating from the ross sea and amundsen sea regions in contrast we find that the southern annular mode sam has little influence on the trajectory cluster frequencies we then develop proxy records for synoptic variability using a shallow firn core from gawn ice piedmont in southern victoria land continental east antarctic trajectory frequency correlates with concentrations of nitrate no3 which is sourced from stratospheric air masses descending over the antarctic interior at seasonal to inter annual scales the frequency of oceanic west antarctic trajectory clusters strongly correlate with deuterium excess which is sensitive to changes in relative humidity and sea surface temperature in the ross and amundsen seas inter annual variability in the frequency of oceanic west antarctic trajectories is discussed with respect to enso and changes in sst and sea ice extent

multiple climate shifts in the southern hemisphere over the past three centuries based on central antarctic snow pits and core studies based on the results of geochemical and glaciological investigations in snow pits and shallow cores regional stack series of air temperature in central antarctica in the southern part of vostok subglacial lake were obtained covering the last 350 years it is shown that this parameter varied quasi periodically with a wavelength of 30 50 years the correlation of the newly obtained record with the circulation indices of the southern hemisphere sh shows that the central antarctic climate is mainly governed by the type of circulation in the sh under conditions of zonal circulation negative anomalies of temperature and precipitation rate are observed whereas the sign of the anomalies is positive during meridional circulation in the 1970s the sign of the relationship between many climatic parameters changed which is likely related to the rearrangement of the climatic system of the sh the data suggest that during the past 350 years such events have taken place at least five times the stable water isotope content of the central antarctic snow is governed by the summer temperature rather than the mean annual temperature which is interpreted as the influence of post depositional effects

observed antarctic interannual climate variability and tropical linkages abstractthis study reviews the mechanisms associated with antarctic tropical climate linkages and presents new analyses of the seasonality and spatial patterns of tropical climate signals in the antarctic for the late 1950s to the present tropical climate signals are primarily communicated to the antarctic via the pacific south america psa pattern and the southern annular mode sam the impacts of these circulation patterns and their tropical linkages are evident in regressions of seasonally stratified antarctic station temperature data and annually resolved ice core records on global fields of sea surface temperature sea level pressure and precipitation temperature and ice core anomalies in the antarctic peninsula region and adjoining areas of west antarctica are significantly impacted by the psa interpreted as a rossby wave train driven by anomalous tropical deep convection during enso events this pattern is most evident in the austral spring consistent with recent studies suggesting that atm

variability and trends in sea ice extent and ice production in the ross sea the trend in ice production the increase in brine rejection in the ross shelf polynya associated with the estimated increase with the ice production however is not consistent with the reported ross sea salinity decrease the locally generated sea ice enhancement of ross sea salinity may be offset by an increase of relatively low salinity of the water advected into the region from the amundsen sea a consequence of increased precipitation and regional glacial ice melt