ensemble simulations of eurasian snow depth anomalies and their influence on the summer asian monsoon the effect of springtime surface conditions over eurasia on the monsoon circulation is addressed by using several simulations with the model used by the european centre for medium range weather forecasts ecmwf the simulations have been specially designed to investigate whether the eurasian snow anomaly is a passive response to the tropical forcing implying that the ultimate relationship exists only between the el nino southern oscillation enso and the monsoon as suggested by previous studies or plays an active independent role in the monsoon modulation preliminary results suggest that the eurasian snow depth is probabilistically predictable and that it does influence the seasonal mean monsoon independently of the enso phase therefore proper observations and simulations of the eurasian snow field can provide an additional and independent contribution to monsoon prediction

relationship between the tibetan snow in spring and the east asian summer monsoon in 2003 a global and regional modeling study in 2003 a climate extreme accompanying a wet and cool summer over east asia was recorded over the east asian countries including central china korea and japan a possible relation of this record breaking summer in east asia to above normal snowfall over the tibetan plateau in spring has been investigated using the national centers for environmental prediction ncep global and regional models the changes in the simulated east asian summer monsoon circulations in response to snow anomalies over tibet are highlighted the results from both global and regional model experiments suggest that above normal snowfall over the tibetan plateau in may induces a weakening of the tibetan high which leads to the formation of favorable upper level circulations accompanying cyclonic circulation anomalies covering the east asian region in summer these circulation anomalies inresponse tothe snow anomalies over theplateau aremore robust and closer towhat wasobserved in the regionalthan inthe global model results the sensitivity experimentsalso show that the precipitation and lower level circulation anomalies in summer caused by the snow anomalies in spring influence the above normal precipitation in the lower reaches of the yangtze river basin as revealed in previous observational studies however the experiments do not fully explain the observed signals in korea and japan since the spring snow anomaly over tibet plays a role in weakening the western pacific subtropical high in the simulated summer whereas in reality the intensity of the high was stronger than normal in 2003

the transition from an active to a passive margin sw end of the south shetland trench antarctic peninsula abstract the lateral ending of the south shetland trench is analysed on the basis of swath bathymetry and multichannel seismic profiles in order to establish the tectonic and stratigraphic features of the transition from an northeastward active to a southwestward passive margin style this trench is associated with a lithospheric scale thrust accommodating the internal deformation in the antarctic plate and its lateral end represents the tip line of this thrust the evolutionary model deduced from the structures and the stratigraphic record includes a first stage with a compressional deformation predating the end of the subduction in the southwestern part of the study area that produced reverse faults in the oceanic crust during the tortonian the second stage occurred during the messinian and includes distributed compressional deformation around the tip line of the basal detachment originating a high at the base of the slope and the collapse of the now inactive accretionary prism of the passive margin the initial subduction of the high at the base of the slope induced the deformation of the accretionary prism and the formation of another high in the shelf the shelf transition high the third stage from the early pliocene to the present day includes the active compressional deformation of the shelf and the base of slope around the tip line of the basal detachment while extensional deformations are active in the outer swell of the trench

decadal transition of the leading mode of interannual moisture circulation over east asia western north pacific bonding to different evolution of enso abstractthe el nino southern oscillation enso cycle has a great impact on the summer moisture circulation over east asia ea and the western north pacific wnp ea wnp on an interannual time s

changes in the relationship between northeast china summer temperature and enso 1 northeast china nec summer temperature tends to be lower higher than normal in el nino la nina developing years during 1950s through mid 1970s the relationship between the nec summer temperature and el nino southern oscillation enso is weakened or even becomes opposite in 1980s and 1990s the present study documents this interdecadal change and investigates plausible reasons for this change before the late 1970s enso affects the nec summer temperature through modulating the south asian heating and consequently the midlatitude asian circulation after the late 1970s the connection between enso and the indian summer monsoon and that between the south asian heating and the midlatitude asian circulation have been weakened this leads to a weakening of enso impacts on the nec summer temperature it is found that the nec summer temperature variations are closely related to the north atlantic sea surface temperature sst and circulation changes in 1980s and 1990s in particular a tripole north atlantic sst anomaly pattern in boreal spring is a good precursory for the nec summer temperature anomalies the nec summer temperature displays a negative correlation with the summer sst surrounding the maritime continent in 1980s and 1990s in many years the tropical north pacific and the north atlantic sst anomalies can contribute in concert to the midlatitude asian circulation changes and the nec summer temperature anomalies these effects overcome those of the central and eastern equatorial pacific sst anomalies leading to a same sign relationship between the nec summer temperature and the central and eastern equatorial pacific sst anomalies

variations of indian and african monsoons induced by insolation changes at 6 and 9 5 kyr bp this study investigates the role of insolation in controlling the indian and african monsoon evolutions during the holocene using coupled ocean atmosphere simulations of 0 6 9 5 kyr bp climates for which only the variations of earth s orbital configuration are considered the two monsoon systems are enhanced at 6 and 9 5 kyr bp compared to 0 kyr bp as a result of the intensified seasonal cycle of insolation in the northern hemisphere the analysis of daily climatologies indicates that even though the length of the celestial summer season is shorter at 9 5 kyr bp the rainy season is longer than at present emphasis is put on the impact of the precession on the seasonality which partly explains why the relative amplification of the indian and african monsoon varies between 9 5 and 6 kyr bp moreover the changes in snow cover over the tibetan plateau play a critical role in reinforcing the 9 5 kyr bp monsoon in india during spring the results suggest that the teleconnection between convection over india and subsidence over the mediterranean regions through the rodwell and hoskins mechanism has an impact on the development of the african monsoon at 9 5 kyr bp

relationship between the indian monsoon rainfall and the tropospheric temperature over the eurasian continent based on climatological data such as the all india rainfall air for 1949 98 air temperatures in the troposphere and at the land surface for 1949 98 as well as precipitation and outgoing long wave radiation olr for 1979 98 the statistical relationship between the indian monsoon rainfall and tropospheric temperature tt over the eurasian continent is examined by using the correlation analysis and singular value decomposition svd analysis methods the main results are summarized as follows 1 the june september jjas air has significant positive correlations with the 200 700 hpa tt averaged for eurasia in jjas the area with the highest simultaneous correlation of upper tt with air for jjas is located in western eurasia there is also a region with positive simultaneous correlations in the southern subtropics covering southern africa the jjas air also shows significant positive correlations with tt over the eurasian continent in march may mam and with the tt averaged over the tibetan plateau in september and october although some precursory springtime temperature signals for the anomalous summer monsoon are found in the upper tt over eurasia the variation in the upper tt appears mostly independent from that of the land surface temperature 2 the anomalies of upper tt in jjas are closely coupled with the variations in olr related to the monsoon rainfall over tropical asia and africa the spatial structure of the first svd mode for olr anomalies shows the coherent variations in convective activity from northern tropical africa to india while the pattern of the first svd mode for 300 hpa temperature anomalies shows a distribution which is nearly symmetric with respect to the equator with variations of the same sign over subtropical areas in both hemispheres and variations of the opposite sign around equatorial africa this pair of coupled patterns suggests that when the monsoon rains from tropical africa to india become more intense the upper troposphere from northern africa to western asia and over southern africa becomes warmer 3 the observed temperature variation in the upper troposphere over the eurasian continent especially western eurasia during the summer monsoon season is considered to be a result of the anomalous subsidence and thermal advection dynamically induced by anomalous tropical heating associated with the enhanced monsoon rainfall this study suggests that the tropical convective activity linked to the indian monsoon rainfall has an impact on the atmospheric variability on a global scale

interdecadal changes in the relationship between southern china winter spring precipitation and enso winter spring precipitation in southern china tends to be higher lower than normal in el nino la nina years during 1953 1973 the relationship between the southern china winter spring precipitation and el nino southern oscillation enso is weakened during 1974 1994 during 1953 1973 above normal southern china rainfall corresponds to warmer sea surface temperature sst in the equatorial central pacific there are two anomalous vertical circulations with ascent over the equatorial central pacific and ascent over southern china and a common branch of descent over the western north pacific that is accompanied by an anomalous lower level anticyclone during 1974 1994 above normal southern china rainfall corresponds to warmer sst in eastern south indian ocean and cooler sst in western south indian ocean two anomalous vertical circulations act to link southern china rainfall and eastern south indian ocean sst anomalies with ascent over eastern south indian ocean and southern china and a common branch of descent over the western north pacific present analysis shows that south indian ocean sst anomalies can contribute to southern china winter spring precipitation variability independently the observed change in the relationship between southern china winter spring rainfall and enso is likely related to the increased sst variability in eastern south indian ocean and the modulation of the pacific decadal oscillation

modulation of the tibetan plateau snow cover on the enso teleconnections from the east asian summer monsoon perspective theeastasiansummermonsoon easm mayexhibitratherlargevariabilitybetweenyearscharacterized by the same enso phase such inconsistency reduces the easm predictability based on enso results in this study show that the tibetan plateau snow cover tpsc exerts a modulating effect on enso teleconnections and enso significantly correlates with the easm only during the reduced tpsc summers three dimensional circulation structures are examined to manifest that the typical enso signals in reduced tpsc summers tend to be stronger than in excessive tpsc summers numerical and theoretical evidences indicate that the anomalously reduced tpsc can force positive geopotential height anomalies at the upper troposphereandweakenthejetstreamsacrosseasternasiaandnorthwesternpacific governedbysuchbasic state zonal flows the extratropical rossby wave response to the enso forcing usually has a larger amplitude and pronounced westward development in such case enso extends its influences to eastern asia and enhances its connection with the easm

cretaceous oblique extensional deformation and magma accumulation in the fosdick mountains migmatite cored gneiss dome west antarctica 1 the fosdick mountains west antarctica expose a 15 x 80 km migmatite cored gneiss dome consisting of migmatitic gneisses diatexite migmatite and subhorizontal leucogranite sheets the fosdick dome was emplaced and exhumed in the mid cretaceous due to oblique extension associated with the west antarctic rift system along the west antarctic new zealand segment of east gondwana the dome is bounded to the south by a dextral oblique detachment structure and to the north by an inferred dextral strike slip fault within the fosdick dome and in the detachment zone granite occupies leucosomes dikes sills and dilatant and shear structures the pattern of kilometer scale domains of migmatite and granite suggest that lithologic variations and heterogeneous deformation boudinage resulted in pressure gradients that enhanced melt flow and magma accumulation in the fosdick dome steep foliations are overprinted folded and transposed by subhorizontal fabrics the crosscutting relationship is interpreted as a transition from wrench deformation to oblique divergence steep structures in the dome host concordant subvertical leucosome and granite sheets yielding shrimp u pb zircon ages between ca 117 and 114 ma prevalent subhorizontal domains host large volumes of subhorizontal diatexite migmatite and granite sheets that yield u pb zircon ages between ca 109 and 102 ma these ages indicate a timescale for melt influx of approximately 15 ma and that the transition from wrench to oblique divergence may have occurred in as little as 5 ma granites with crystallization ages between ca 109 and 102 ma were also emplaced in the south fosdick detachment zone indicating that the detachment was active during oblique divergence shrimp u pb titanite ages between ca 102 and 97 ma for late to post tectonic diorite dikes are interpreted as emplacement ages and give a minimum age for gneissic foliation development during detachment faulting the fosdick mountains preserve a record of the middle to lower crustal response to a transition from wrench to oblique extensional deformation overprinting structural relationships show that a change in the angle of oblique extension can induce accumulation of subhorizontal magma sheets and lead to initiation of a detachment zone

thermal history and exhumation of basement rocks from mesozoic to cenozoic subduction cycles central north island new zealand a new thermochronological study of the basement rocks of the central north island new zealand records thermal and exhumation histories related to two subduction cycles since the latest jurassic the basement comprises metasedimentary terranes accreted onto eastern gondwana during mesozoic subduction since the oligocene these terranes have been located on the hanging wall of the hikurangi subduction margin overriding the pacific plate results of zircon fission track 121 264 ma analysis yield detrital or slightly reset ages apatite fission track 19 8 122 ma and u th sm he 10 3 95 2 ma ages are fully reset results from inverse thermal history modeling of the data of individual and stacked samples imply the following 1 after their accretion the basement rocks were cooled and exhumed to shallow depths of the crust in the early cretaceous by 150 135 ma this was followed by an episode of reheating until 100 ma which we interpret to be the result of burial by sedimentation above the accretionary wedge during extensional deformation caused by continued underplating and thickening of the wedge from beneath 2 from 100 ma our data indicate thermotectonic quiescence until the oligocene 27 ma 3 during initiation of the hikurangi margin the fore arc proto axial ranges began to exhume during the late oligocene to early miocene 27 20 ma subduction triggered unroofing removed 1 2 2 8 km of overburden most of which was probably the less lithified passive margin sediments 4 along the western central north island the exhumational response to the hikurangi subduction was limited with a total magnitude of erosion 1 5 km in the cenozoic

an interdecadal change in the relationship between boreal spring arctic oscillation and the east asian summer monsoon around the early 1970s previous studies suggested that the boreal spring arctic oscillation ao exerts a pronounced influence on the following east asian summer monsoon easm variability this study reveals that the relationship of spring ao with the following easm experienced a significant interdecadal change in the early 1970s the influence of spring ao on the following easm is weak during the 1950s and 1960s but strong and significant during the mid 1970s through the mid 1990s the spring ao related sea surface temperature sst atmospheric circulation and heating anomalies are compared between 1949 71 and 1975 97 results show that the spring ao related cyclonic circulation anomaly over the tropical western north pacific is weaker and located more northward in the former epoch than in the latter epoch correspondingly sst atmospheric circulation and heating anomalies over the tropical north pacific are located more northeastward in the former than latter epoch from spring to summer in the following summer the spring ao related cyclonic circulation anomalies over the tropical north pacific are located farther away from east asia in the former epoch this interdecadal change in the ao easm connection may be attributed to a significant change in the intensity of spring north pacificsynoptic scaleeddyactivityaroundtheearly1970sfromaweakregimetoastrongregime whichinduces a stronger eddy feedback to the low frequency mean flow after the early 1970s this may explain a stronger spring ao related cyclonic circulation over the tropical western north pacific and thus a closer relationship between the spring ao and the following easm in the latter than former epoch

climatology and variability of historical soviet snow depth data some new perspectives in snow indian monsoon teleconnections this study presents the monthly climatology and variability of the historical soviet snow depth data this data set was developed under the bilateral data exchange agreement between united states of america and the former union of soviet socialist republics the original data is for 284 stations for periods varying from 1881 upto 1985 the seasonal cycle of the mean snow depth has been presented both as spatial maps and as averages over key locations the deepest snow 80 cms day areas are found over siberia in particular over 80 100 e 55 70 n during march over the course of the annual cycle average snow depth over this region changes dramatically from about 10 cms in october to about 80 cms in march the variability is presented in the form of spatial maps of standard deviation to investigate the interaction of snow depth with indian monsoon rainfall imr lag and lead correlation coefficients are computed results reveal that the winter time snow depth over western eurasia surrounding moscow eastern eurasia in central siberia shows significant negative positive relationship with subsequent imr following the monsoon the signs of relationship reverse over both the regions this correlation structure is indicative of a midlatitude longwave pattern with an anomalous ridge trough over asia during the winter prior to a strong weak monsoon as the time progresses from winter to spring the coherent areas of significant relationship show southeastward propagation empirical orthogonal function analysis of the snow depth reveal that the first mode describes a dipole type structure with one centre around moscow and the other over central siberia depicting similar pattern as the spatial correlation structure the decadal scale imr variations seem to be more associated with the northern hemisphere midlatitude snow depth variations rather than with the tropical enso el nino southern oscillation variability

decadal change of the spring snow depth over the tibetan plateau the associated circulation and influence on the east asian summer monsoon abstract the decadal change in the spring snow depth over the tibetan plateau and impact on the east asian summer monsoon are investigated using station observations of snow depth data and the ncep ncar reanalysis for 1962 93 during spring march april both the domain averaged snow depth index sdi and the first principal component of the empirical orthogonal function eof analysis exhibit a sharp increase in snow depth after the late 1970s which is accompanied by excessive precipitation and land surface cooling the correlation between sdi and precipitation shows a coherent remote teleconnection from the tibetan plateau northern india to western asia it is found that the increased snow depth over the plateau after the mid 1970s is concurrent with a deeper india burma trough an intensified subtropical westerly jet as well as enhanced ascending motion over the tibetan plateau additional factors for the excessive snowfall include more moisture supply associated with the intensification of the south

relation between eurasian snow cover snow depth and the indian summer monsoon an observational study abstract satellite derived snow cover data for 22 yr and snow depth data for 9 yr over eurasia have been analyzed to reexamine the possible relation of snow with the indian summer monsoon in contrast to the previous studies that use snow cover averaged over all of eurasia as a single number the frequency of occurrence of snow at each grid point over eurasia is correlated with the indian summer monsoon rainfall thus specific geographical regions over eurasia that are responsible for the well known inverse relationship between eurasian snow cover and indian monsoon rainfall are delineated it is found somewhat surprisingly that western eurasia is the only geographical region for which a significant inverse correlation exists between winter snow cover and subsequent summer monsoon rainfall however composites for high and low snow cover over eurasia show spatially homogeneous large scale patterns of snow cover and surface temperature anomalies winters of high and low snow cover for eurasia are found t

regional change in snow water equivalent surface air temperature relationship over eurasia during boreal spring present study investigates local relationship between surface air temperature and snow water equivalent swe change over mid and high latitudes of eurasia during boreal spring positive correlation is generally observed around the periphery of snow covered region indicative of an effect of snow on surface temperature change in contrast negative correlation is usually found over large snow amount area implying a response of snow change to wind induced surface temperature anomalies with the seasonal retreat of snow covered region region of positive correlation between swe and surface air temperature shifts northeastward from march to may a diagnosis of surface heat flux anomalies in april suggests that the snow impact on surface air temperature is dominant in east europe and west siberia through modulating surface shortwave radiation in contrast atmospheric effect on swe is important in siberia and russia far east through wind induced surface sensible heat flux change further analysis reveals that atmospheric circulation anomalies in association with snowmelt over east siberia may be partly attributed to sea surface temperature anomalies in the north atlantic and the atmospheric circulation anomaly pattern associated with snowmelt over russia far east has a close association with the arctic oscillation

mechanisms of abrupt climate change of the last glacial period 1 more than a decade ago ice core records from greenland revealed that the last glacial period was characterized by abrupt climate changes that recurred on millennial time scales since their discovery there has been a large effort to determine whether these climate events were a global phenomenon or were just confined to the north atlantic region and also to reveal the mechanisms that were responsible for them in this paper we review the available paleoclimate observations of abrupt change during the last glacial period in order to place constraints on possible mechanisms three different mechanisms are then reviewed ocean thermohaline circulation sea ice feedbacks and tropical processes each mechanism is tested for its ability to explain the key features of the observations particularly with regard to the abruptness millennial recurrence and geographical extent of the observed changes it is found that each of these mechanisms has explanatory strengths and weaknesses and key areas in which progress could be made in improving the understanding of their long term behavior both from observational and modeling approaches are suggested finally it is proposed that a complete understanding of the mechanisms of abrupt change requires inclusion of processes at both low and high latitudes as well as the potential for feedbacks between them some suggestions for experimental approaches to test for such feedbacks with coupled climate models are given

unroofing of fore arc ranges along the hikurangi margin new zealand constraints from low temperature thermochronology abstract the axial ranges of north island new zealand parallel the hikurangi subduction margin they consist of uplifted and exhumed mesozoic meta sedimentary basement rocks of the overriding australian plate beneath which the pacific plate has been subducting since at least the late oligocene we investigate the unroofing histories of these fore arc mountains during the evolution of the hikurangi margin based on new and previous zircon and apatite fission track and apatite u th sm he data which we interpret based on inverse modelling the results suggest that the exhumation of rocks in the axial ranges initiated in the west and migrated trench wards towards the east onsets of accelerated exhumation in different parts of the ranges indicate significant eastwards thrusting on the margin parallel ngamatea fault before 20 17 ma and on the wellington mohaka fault before 10 7 ma the exhumation rate has varied significantly along strike since the late miocene lower in the central part of the axial ranges and significantly higher to the south since the late miocene the increasing exhumation rate from the central to southern axial ranges is consistent with the clockwise vertical axis rotation of eastern north island relative to the australian plate in the hikurangi margin although underplating of subducted material at the basal upper plate may have contributed to localised rock uplift e g in the raukumara range we suggest that the shortening of the fore arc upper plate was the chief driver of unroofing of the proto axial ranges

asian monsoon variations revealed from stable isotopes in precipitation to further our understanding of the asian monsoon system particularly the onset dates of monsoon sub systems over their respective east asian domains we present an 8 year 2007 2014 dataset of oxygen isotopes of precipitation 18op from three stations lulang and nuxia in southeastern tibetan plateau setp and guangzhou in southeastern coastal china secn the general agreement between isotopically identified monsoon onset dates with those identified by the meridional temperature gradient suggests that the initially sustained isotopic depletion is sensitive to the evolving thermal contrast between the eurasian continent and the indian ocean the 850 hpa meridional wind over nearby oceans is an efficient bridge linking isotopic variations in both regions with their respective monsoon sub systems the intensity of the south asian high and tropical cyclone frequencies show stronger effects on isotopic depletion in the secn than in the setp and on monsoon onset timing over the south china sea tibetan plateau snow cover anomalies are significantly correlated with 18op in both regions on monthly timescales

pacific east asian teleconnection how does enso affect east asian climate observational evidence is presented to show a teleconnection between the central pacific and east asia during the extreme phases of enso cycles this pacific east asian teleconnection is confined to the lower troposphere the key system that bridges the warm cold events in the eastern pacific and the weak strong east asian winter monsoons is an anomalous lower tropospheric anticyclone cyclone located in the western north pacific the western north pacific wind anomalies develop rapidly in late fall of the year when a strong warm or cold event matures the anomalies persist until the following spring or early summer causing anomalously wet dry conditions along the east asian polar front stretching from southern china northeastward to the east of japan kuroshio extension using atmospheric general circulation and intermediate models the authors show that the anomalous philippine sea anticyclone results from a rossby wave response to suppressed convective heating which is induced by both the in situ ocean surface cooling and the subsidence forced remotely by the central pacific warming the development of the anticyclone is nearly concurrent with the enhancement of the local sea surface cooling both the anticyclone and the cooling region propagate slowly eastward the development and persistence of the teleconnection is primarily attributed to a positive thermodynamic feedback between the anticyclone and the sea surface cooling in the presence of mean northeasterly trades the rapid establishment of the philippine sea wind and sst anomalies implies the occurrence of extratropical tropical interactions through cold surge induced exchanges of surface buoyancy flux the central pacific warming plays an essential role in the development of the western pacific cooling and the wind anomalies by setting up a favorable environment for the anticyclone sst interaction and midlatitude tropical interaction in the western north pacific

response of the indian summer monsoon circulation and rainfall to seasonal snow depth anomaly over eurasia several observational and modeling studies indicate that the indian summer monsoon rainfall ismr is inversely related to the eurasian snow extent and depth the other two important surface boundary conditions which influence the ismr are the pacific sea surface temperature sst to a large extent and the indian ocean sst to some extent in the present study observed soviet snow depth data and indian rainfall data for the period 1951 1994 have been statistically analyzed and results show that 57 of heavy snow events and 24 of light snow events over west eurasia are followed by deficient and excess ismr respectively out of all the extreme monsoon years care has been taken to identify those when eurasian snow was the most dominant surface forcing to influence ismr during the years of high low eurasian snow amounts in spring winter followed by deficient excess ismr atmospheric fields such as temperature wind geopotential height velocity potential and stream function based on ncep ncar reanalyses have been examined in detail to study the influence of eurasian snow on the midlatitude circulation regime and hence on the monsoon circulation results show that because of the west eurasian snow anomalies the midlatitude circulations in winter through spring show significant changes in the upper and lower level wind geopotential height velocity potential and stream function fields such changes in the large scale circulation pattern may be interpreted as precursors to weak strong monsoon circulation and deficient excess ismr the upper level velocity potential difference fields between the high and low snow years indicate that with the advent of spring the winter anomalous convergence over the indian region gradually becomes weaker and gives way to anomalous divergence that persists through the summer monsoon season also the upper level anomalous divergence centre shifts from over the northern hemisphere and equator to the southern hemisphere over the indian ocean and australia

observed relationship of spring and summer east asian rainfall with winter and spring eurasian snow abstract this study investigates the relationship between spring and summer rainfall in east asia and the preceding winter and spring snow cover depth over eurasia using station rainfall observations satellite observed snow cover satellite derived snow water equivalent and station observations of the number of days of snow cover and snow depth correlation analysis shows that snow depth anomalies can persist from winter to spring whereas snow cover anomalies cannot in most regions of eurasia locally snow cover and snow depth anomalies in february are not related in most regions to the north of 50 n but those anomalies in april display consistent year to year variations the results suggest that the winter snow cover cannot properly represent all the effects of snow and it is necessary to separate the winter and spring snow cover in addressing the snow monsoon relationship spring snow cover in western siberia is positively correlated with spring rainfall in southern china the circulation anomalies

using idealized snow forcing to test teleconnections with the indian summer monsoon in the hadley centre gcm anomalous heavy snow during winter or spring has long been regarded as a possible precursor of deficient indian monsoon rainfall during the subsequent summer however previous work in this field is inconclusive in terms of the mechanism that communicates snow anomalies to the monsoon summer and even the region from which snow has the most impact in this study we explore these issues in coupled and atmosphere only versions of the hadley centre model a 1050 year control integration of the hadcm3 coupled model which well represents the seasonal cycle of snow cover over the eurasian continent is analysed and shows evidence for weakened monsoons being preceded by strong snow forcing in the absence of enso over either the himalaya tibetan plateau or north west eurasia regions however empirical orthogonal function eof analysis of springtime interannual variability in snow depth shows the leading mode to have opposite signs between these two regions suggesting that competing mechanisms may be possible to determine the dominant region ensemble integrations are carried out using hadam3 the atmospheric component of hadcm3 and a variety of anomalous snow forcing initial conditions obtained from the control integration of the coupled model forcings are applied during spring in separate experiments over the himalaya tibetan plateau and north west eurasia regions in conjunction with climatological ssts in order to avoid the direct effects of enso with the aid of idealized forcing conditions in sensitivity tests we demonstrate that forcing from the himalaya region is dominant in this model via a blanford type mechanism involving reduced surface sensible heat and longwave fluxes reduced heating of the troposphere over the tibetan plateau and consequently a reduced meridional tropospheric temperature gradient which weakens the monsoon during early summer snow albedo is shown to be key to the mechanism explaining around 50 of the perturbation in sensible heating over the tibetan plateau and accounting for the majority of cooling through the troposphere

on the association between spring arctic sea ice concentration and chinese summer rainfall 1 a statistical relationship between spring arctic sea ice concentration sic and chinese summer rainfall is identified using singular value decomposition svd results show that decreased increased spring sic in the arctic ocean and the greenland sea corresponds to increased decreased summer rainfall in northeast china and central china between the yangtze river and the yellow river 28 36 n and decreased increased rainfall in south china corresponding summer 500 hpa height anomalies show a eurasian wave train structure which originates in northern europe and extends southeastwards to northeast china and a south north dipole structure over east asia south to lake baikal such a spatial distribution of 500 hpa height anomalies and corresponding summer rainfall anomalies cannot be entirely attributed to the impact of east asian summer monsoon easm variability the spring arctic sic provides a complementary precursor for chinese summer rainfall variability the combined impacts of both spring arctic sic and eurasian snow cover on the eurasian wave train may explain their statistical linkage

an interdecadal change in southern china summer rainfall around 1992 93 the present study documents a pronounced interdecadal change in summer rainfall over southern china around 1992 93 and explores the plausible reasons for this change the summer rainfall is persistently below normal during 1980 92 and above normal during 1993 2002 coherent changes in atmospheric circulation are identified over east asia and the south china sea scs western north pacific wnp the increase in rainfall is accompanied by an increase in lower level convergence midtropospheric ascent and upperlevel divergence over southern china the changes in lower level winds feature two anomalous anticyclones one over the scs subtropical wnp and the other over north china mongolia the outflows from the two anomalous anticyclones converge over southern china leading to anomalous moisture convergence enhanced ascent and increased rainfall the development of the northern anticyclone is related to an increase in the tibetan plateau snow cover in the preceding winter spring that leads to a contrast in temperature change between the plateau and the surrounding regions the relatively small temperature change over the plateau coupled with increases in temperature to the west and the east leads to an increase in surface pressure extending northward from the plateau the development of the southern anticyclone is related to an increase in sea surface temperature in the equatorial indian ocean that enhances lower level convergence and ascent the accompanying upper level divergent flows from the tropical indian ocean to the scs wnp lead to the development of anomalous descent and lower level anomalous anticyclone over the scs wnp

two distinct patterns of spring eurasian snow cover anomaly and their impacts on the east asian summer monsoon 1 the eurasian snow cover anomaly in spring has been considered as one of the important factors affecting east asian summer monsoon easm the spring snow cover data for the period from 1972 to 2004 are used to extract dominant spatial patterns over the eurasian region and to examine their impacts on the easm through empirical orthogonal function eof analysis the first eof mode is generally characterized by a continent wide snow cover anomaly over the whole eurasian region while the second eof mode is dominated by an east west dipole structure over eurasia our study indicates that the variability of dipole pattern snow cover is more closely related to the easm rainfall than that of continent wide snow cover a strong dipole pattern with positive negative snow cover anomalies over western eurasia and negative positive snow cover anomalies over eastern eurasia signifies enhanced reduced summer rainfall over east asia and the eurasian wave train pattern is apparent an important implication of these results is that the spring snow cover anomaly over eurasia provides a complementary precursor for easm variability

dynamics of the pacific north american plate boundary in the western united states the vertically averaged deviatoric stress tensor field within the western united states was determined with topographic data geoid data recent global positioning system observations and strain rate magnitudes and styles from quaternary faults gravitational potential energy differences control the large fault normal compression on the california coast deformation in the basin and range is driven in part by gravitational potential energy differences but extension directions there are modified by plate interaction stresses the california shear zone has relatively low vertically averaged viscosity of about 1021 pascal seconds whereas the basin and range has a higher vertically averaged viscosity of 1022pascal seconds

impacts of the global sea surface temperature anomaly on the evolution of circulation and precipitation in east asia on a quasi quadrennial cycle based on multi source observational data from 1979 to 2013 we investigate the evolution of the global sea surface temperature anomaly ssta on a quasi quadrennial cycle and its impact on the seasonal evolution of circulation and precipitation in east asia we do this by using principal oscillation pattern analysis and associated correlation pattern analysis together with numerical experiments from an atmospheric general circulation model the results indicate that the global ssta exerts profound impacts on the east asian climate anomaly while distinct responses exist between the ssta developing and decaying stages from winter to autumn in the developing year southern china is typically wetter than normal in the decaying year however the precipitation over most parts of east asia is above normal from winter to spring and the main rainfall band meandering from the yangtze river to south japan is enhanced in summer during the developing and decaying years an upper level anomalous cyclone moves from northeast asia to the tibetan plateau and then retreats back a low level anomalous cyclone occurs over northeast asia in spring but weakens in summer and then strengthens gradually from autumn to the following summer an anomalous philippine sea anticyclone occurs in winter and spring but is replaced by an anomalous cyclone in summer before reappearing and persisting from autumn to the decaying year the abrupt change in circulation patterns in summer of the developing year might be related to the anomalous weakening of the tibetan plateau heating these anomalies can be attributed to the combined effects of the global large scale heating regional scale oceanic forcing and thermal feedback of the land

contrasting eurasian spring and summer climate anomalies associated with western and eastern eurasian spring snow cover changes spring snow cover variations over eurasia consist of a same sign component and a west east dipole component the same sign component is dominant during late 1970s through 1980s and the two components are equally important during 1990s and 2000s present study contrasted eurasian spring and summer climate anomalies associated with western and eastern eurasian spring snow cover variations and between 1975 1989 and 1993 2007 and found notable differences and obvious interdecadal changes in eurasian climate anomalies after 1990 spring surface temperature anomalies display an obvious west east contrast pattern consistent with a prominent atmospheric wave pattern over eurasia the temperature anomalies are larger corresponding to western than eastern eurasian snow cover change snow albedo effect plays a main role in temperature change during 1975 1989 whereas atmospheric processes also contribute largely to temperature change during 1993 2007 large soil moisture anomalies occur corresponding to western eurasian snow cover and during 1975 1989 the snow hydrological effect on summer precipitation is mainly detected over the west siberian plain where soil moisture anomalies persist over 3 months over most of other eurasian regions atmospheric circulation pattern plays a dominant role in summer surface temperature and precipitation variations the relationship of indian summer rainfall to western eurasian spring snow cover was weakened since the mid 1990s and the correlation of northeast china summer rainfall with local spring snow cover changed from positive to negative around 1990

the chiwaukum structural low cenozoic shortening of the central cascade range washington state usa comment cheney and hayman 2009 1 bring welcome attention to a critical issue in the understanding of the cenozoic history of the pacific northwest namely the timing and kinematics of eocene sedimentation and deformation their study provides valuable detailed geologic mapping interpreted cross

the effect of enso on tibetan plateau snow depth a stationary wave teleconnection mechanism and implications for the south asian monsoons abstract an atmospheric stationary wave teleconnection mechanism is proposed to explain how enso may affect the tibetan plateau snow depth and thereby the south asian monsoons using statistical analysis the short available record of satellite estimates of snow depth and ray tracing it is shown that wintertime enso conditions in the central pacific may produce stationary barotropic rossby waves in the troposphere with a northeastward group velocity these waves reflect off the north american jet turning equatorward and enter the north african asian jet over the eastern atlantic ocean once there the waves move with the jet across north africa south asia the himalayas and china anomalous increases in upper tropospheric potential vorticity and increased wintertime snowfall over the tibetan plateau are speculated to be associated with these rossby waves the increased snowfall produces a larger tibetan plateau snowpack which persists through the spring and summer and weakens the intensity of the

change in the contribution of spring snow cover and remote oceans to summer air temperature anomaly over northeast china around 1990 sea surface temperature sst snow cover and soil moisture anomalies are factors for climate variability over land regions the present study found that the relationship between in situ spring snow cover and northeast china summer surface temperature variations is not steady it is significant during mid 1970s through late 1980s but weak during the 1990s and 2000s this interdecadal change in the spring snow cover summer temperature relationship is found to relate to the effects of sst anomalies in the tropical indian ocean and western pacific regions during the recent decades these sst anomalies induce a meridional circulation pattern along the east asian coast the remote sst forcing induced circulation and precipitation anomalies overcome local snow cover induced soil moisture anomalies and thus disrupt the spring snow cover summer temperature connection during the recent decades the present study indicated that both the north atlantic sst anomaly pattern and local spring snow cover anomalies contribute to northeast china summer temperature variations during mid 1970s through late 1980s during the 1990s and 2000s the influence of the north atlantic sst anomalies is weakened and the sst anomaly in the tropical indo western pacific region is a major player in northeast china summer temperature variations

zoned cretaceous and cenozoic garnet and the timing of high grade metamorphism southern alps new zealand new garnet sm nd and lu hf and existing rb sr 40ar 39ar u pb and sm nd ages and data on deformational fabrics and mineral compositions show for the first time that the garnet growth and ductile deformation in the alpine schist belt and southern alps orogen new zealand are diachronous and partly cenozoic in age the dominant metamorphic isograds in the alpine schist formed during crustal thickening at a previously unsuspected time at c 86 ma immediately prior to the opening of the tasman sea at c 84 82 ma obvious changes in the textures and compositional zoning patterns of garnet are not always reliable indicators of polymetamorphism and fabric elements can be highly diachronous a detailed timing history for the growth of a single garnet is recorded by a sm nd garnet whole rock age of 97 8 8 1 ma for the inmost garnet core zone 1 lu hf ages of 86 2 0 2 ma and 86 3 0 2 ma for overgrowth zones 2 and 3 a step leach sm nd age of 12 37 ma for zone 4 and growth of the garnet rim zone 5 over the alpine fault mylonite foliation during the modern phase of oblique collision that began at c 5 6 ma plate convergence along the new zealand portion of the gondwana margin continued after c 105 ma almost certainly culminating in the oblique collision of a large oceanic plateau hikurangi plateau the metamorphism of the alpine schist at c 86 ma is evidence of that hit the mid to late cretaceous extension that is widespread elsewhere in the new zealand region is attributed to upper plate extension and slab roll back the effects of the collision with the hikurangi plateau may have contributed to the changing plate motions in the region leading up to the opening of the tasman sea at c 82 ma

cretaceous termination of subduction at the zealandia margin of gondwana the view from the paleo trench abstract during the permian to cretaceous zealandia occupied a position on the proto pacific facing convergent margin of gondwana subduction on this margin ceased somewhere between 105 ma and perhaps 70 ma but the timing of this tectonic transition remains controversial resolution of this uncertainty is important for tectonic reconstructions of the southwest pacific and for global plate tectonic models here we revisit the problem by reference to new stratigraphic and geochemical data from the east coast basin of new zealand which occupied a position adjacent to and possibly superimposed on the relict cretaceous subduction trench at the time subduction ceased this basin is expected to preserve direct structural and stratigraphic evidence for or against late cretaceous subduction in western parts of the east coast basin the western sub belt a conspicuous unconformity separates undoubted accretionary prism rocks of the torlesse composite terrane from younger cretaceous cover units strata beneath and overlying this unconformity vary in age from place to place but abundant paleontological data and published ages of detrital zircons some reinterpreted herein indicate that exposed torlesse rocks are nowhere younger than 100 ma overlying zealandia megasequence cover strata are mostly younger than 110 ma between 110 and 85 ma the entire length of the western sub belt reveals complex stratigraphic architecture of relatively small scale depocentres subjected to alternating episodes of subsidence and local uplift and erosion there is widespread evidence for compression on the western sub belt over this period although the overall amount of shortening is likely to be relatively modest in contrast the eastern sub belt preserves a record of near continuous and apparently simple deposition over the same interval of time we see little and somewhat equivocal evidence for extension in either sub belt through the late cretaceous superimposed on this general pattern we observe discrete widespread or basin wide tectonic events at 95 ma and within the intervals 86 83 ma and 83 81 ma indicated by the presence of unconformities and sedimentary facies changes importantly all these events can be correlated with coeval events recorded elsewhere in zealandia suggesting that the east coast basin was subject to the same tectonic regime as the rest of zealandia and shared a common history during the mid to late cretaceous integrating these findings with data from elsewhere in zealandia we argue that there is diverse evidence to indicate that subduction finished along the new zealand segment of the gondwana margin by 100 ma that said the causes of on going late cretaceous compression in the east coast basin and in other parts of zealandia are not well constrained although several possible explanations are plausible there are few analogue abandoned subduction margins described in the literature however the situation in the south shetland trench shows strong similarities with patterns and complexities observed in the east coast basin

impact of eurasian spring snow decrement on east asian summer precipitation abstractin this study the relationship between eurasian spring snow decrement ssd and east asian summer precipitation and related mechanisms were investigated using observational data and the community atmospheric model version 3 1 cam3 1 the results show that a west east dipole pattern in eurasian ssd anomalies with a negative center located in the region between eastern europe and the west siberia plain eewsp and a positive center located around baikal lake bl is significantly associated with east asian summer precipitation via triggering an anomalous midlatitude eurasian wave train reduced ssd over eewsp corresponds to anomalously dry local soil conditions from spring to the following summer thereby increasing surface heat flux and near surface temperatures similarly the increase in ssd over bl is accompanied by anomalously low near surface temperatures the near surface thermal anomalies cause an anomalous meridional temperature gradient which intensifies the lower level baroclinicit

impacts of the atlantic multidecadal oscillation on the relationship of the spring arctic oscillation and the following east asian summer monsoon abstractprevious studies indicated that spring arctic oscillation ao can influence the following east asian summer monsoon easm this study reveals that the atlantic multidecadal oscillation a

potential impacts of northeastern eurasian snow cover on generation of dust storms in northwestern china during spring the effects of the northeastern eurasian snow cover on the frequency of spring dust storms in northwestern china have been examined for the period 1979 2007 averaged over all 43 stations in northwestern china a statistically significant relationship has been found between dust storm frequency dsf and eurasian snow water equivalent swe during spring mean dsf of 7 4 and 3 3 days for years of high and low swe respectively further analyses reveal that positive swe anomalies enhance the meridional gradients of the lower tropospheric temperatures and geopotential heights thereby strengthening westerly jets and zonal wind shear over northwestern china and western inner mongolia of china the regions of major dust sources the anomalous atmospheric circulation corresponding to the eurasian swe anomalies either reinforces or weakens atmospheric baroclinicity and cyclogenesis according to the sign of the anomaly to affect the spring dsf this study suggests that eurasian swe anomalies can be an influential factor of spring dsf in northwestern china and western inner mongolia of china

indices of el nino evolution abstract to characterize the nature of el nino southern oscillation enso sea surface temperature sst anomalies in different regions of the pacific have been used an optimal characterization of both the distinct character and the evolution of each el nino or la nina event is suggested that requires at least two indices i sst anomalies in the nino 3 4 region referred to as n3 4 and ii a new index termed here the trans nino index tni which is given by the difference in normalized anomalies of sst between nino 1 2 and nino 4 regions the first index can be thought of as the mean sst throughout the equatorial pacific east of the date line and the second index is the gradient in sst across the same region consequently they are approximately orthogonal tni leads n3 4 by 3 to 12 months prior to the climate shift in 1976 77 and also follows n3 4 but with opposite sign 3 to 12 months later however after 1976 77 the sign of the tni leads and lags are reversed

persistent severe drought in southern china during winter spring 2011 large scale circulation patterns and possible impacting factors 1 severe drought persisted in southern china from january to may in 2011 in this study a statistical analysis is carried out to discuss the multiple possible impacting factors including la nina the north atlantic oscillation nao and the thermal condition of the tibetan plateau tp the la nina event in 2010 11 excited a lower tropospheric anomalous cyclone over the northwestern pacific weakening the northwestern pacific subtropical high and caused an eastward shift of the high as a result transportation of wet and warm moisture from tropical oceans to southern china decreased the la nina event also strengthened the upper tropospheric east asian jet stream and deepened the east asian trough favoring a southward intrusion of dry northerly flow from the siberia the la nina condition in the previous two seasons also seemed to provide precursory signals for the drought moreover in january may 2011 the nao was in a positive phase and it tended to excite stationary rossby waves that were distributed along the sub polar and subtropical waveguides respectively the sub polar one induced an anomalous anticyclone over the siberia favoring a southward intrusion of high latitude northerly flow to southern china the subtropical one associated possibly with the enhanced convection over the broad region from the mediterranean to sahara was favorable for an influence of upper tropospheric flow on southern china the tp might also exert an influence on the drought by weakening the westerly flow to the southern flank of tp and reducing water vapor transport from the bay of bengal to southern china

possible impact of north atlantic warming on the decadal change in the dominant modes of winter eurasian snow water equivalent during 1979 2015 an east west dipole mode of winter eurasian snow water equivalent swe is found during the period of 1979 2015 it accounts for about 23 4 of the total variance and displayed a significant decadal change in the early 2000s the basin warming footprint of the north atlantic likely exerted an influence on this decadal change and the observation based evidence is reproduced by numerical experiments using the community atmosphere model cam3 1 a basin wide warming of north atlantic sea surface temperature induced atmospheric anomalies by exciting a stationary rossby wave train which prorogates from the subtropical north atlantic to the mid to high latitudes of the eurasian continent along with the rossby wave train an enhanced upper level ridge occurs over the ural mountain and a deepened upper level trough appears over the eastern siberian plateau which promotes heavy snowfall over the eastern siberian plateau and light snowfall to its west thus it is plausible that the north atlantic warming plays a role in exciting the rossby wave train to modulate the decadal change in the east west dipole swe mode of the extratropical eurasian continent the possible moisture transport paths associated with the decadal change in the east west dipole swe mode are also discussed

predictability of snow depth anomalies over eurasia and associated circulation patterns summary this study investigates the variability and predictability of snow depth anomalies over the eurasian continent at the end of winter as represented in 12 ensembles of general circulation model simulations performed at the european centre for medium range weather forecasts each ensemble includes nine integrations performed with the same prescribed sea surface temperature but started from time lagged initial conditions an empirical orthogonal function eof analysis shows that the leading eof of eurasian snow depth in march has a zonallyoriented dipole structure with a band of positive anomalies covering northem europe and siberia and negative anomalies over central europe the himalayas and north china a significant relationship is found between the positivehegative phase of this snow depth anomaly and warm cold el niiio southern oscillation events the positive phase of the snow depth eofl is associated with a wintertime circulation characterized by a strengthening of the westerly winds over europe and siberia in the upper troposphere this westerly anomaly is accompanied by negative zonal wind anomalies over eurasia around 3w n and positive zonal wind anomalies between the equator and 25 n over africa and south east asia a good degree of predictability is found in the snowrelated circulation anomalies considering 500 hpa height 850 hpa zonal wind and 200 hpa zonal wind the interannual variations of the ensemble mean fields show a correlation of 48 56 and 65 respectively with the corresponding observed anomalies over the eastern half 0 to 180 e of the northern hemisphere the tropical component of the zonal wind anomaly associated with snow depth eofl is strongly predictable it shows a marked persistence from winter to the early summer and affects the large scale circulation over south asia in the early and central periods of the monsoon season

geochemistry and tectonic setting of matakaoa volcanics east coast allochthon new zealand suprasubduction zone affinity regional correlations and origin in north eastern new zealand the late cretaceous to eocene submarine volcanic rocks of the east coast allochthon referred to as matakaoa volcanics formed a dominantly mafic melange with minor abyssal sediments during the subduction of oceanic crust accreted and melanged pillow lavas and dolerites display the geochemical and isotopic features of tholeiites with some diversity referred to as midocean ridge basalts island arc tholeiites and back arc basin basalts the association of supra subduction tholeiitic magmas abyssal sediments and polymetallic volcanogenic sulphide deposits is typical of many back arc basins therefore a correlation with the alkaline and transitional basalts of the hikurangi manihiki ontong java plateau may be ruled out these petrological features and the fossil ages as well are closely similar to those of the tangihua complex northland allochthon and allow matakaoa and tangihua mafic volcanic rocks now separated by the modern havre trough to be correlated within one single late cretaceous to eocene 2 basin the consideration of possible younger ages oligocene is also discussed the occurrence of late cretaceous eocene oceanic crust with supra subduction zone affinities to the east of the norfolk ridge poses the problem of the intervening southwest dipping subduction the missing late cretaceous eocene arc and their relationship with southeast gondwana marginal break up

retracted article reexamining the impact of tibetan snow anomalies to the east asian summer monsoon using modis snow retrieval based on recent moderate resolution imaging spectroradiometer high resolution snow retrieval data over the tibetan plateau the connection of snow anomalies to the east asian summer monsoon has been reexamined to eliminate the uncertainty of the previous snow mapping in this region the snow monitoring shows relatively large interannual variations over the tibetan plateau during winter and spring the snow anomalies however show relatively short persistence usually less than 3 months that is substantial shorter than previous studies the anomalous snow pack in the spring shows a good correlation to the onset of the east asian monsoon but does not show a significant relationship with the intensity of the summer monsoon as suggested by previous studies the sequential thermal forcing of snow anomalies to the general circulation and monsoon onset over east asia is further investigated a positive negative snow anomalies during spring will change the energy and water exchange at the land surface suppressing enhancing the sensible heating over the tibetan delaying accelerating the reversal of the meridional temperature gradient between the eurasian continent and the tropical ocean and further impact the onset of east asian monsoon

el nino impacts on precipitation in the western north pacific east asian sector abstract in this study the western north pacific east asian wnp ea rainfall anomaly induced by the strong el nino in 1982 83 1991 92 and 1997 98 and its association with the mean state are examined over the northern part of the wnp ea region north of 20 n which is dominated by southwest northeast tilting frontal systems positive rainfall anomalies from the fall before the el nino peak phase year 0 to the first wet period after the peak phase year 1 are affected by low and midlevel horizontal moisture convergence anomalies induced by low level anticyclonic circulation anomalies over the wnp region that are associated with el nino over the southern part of the wnp ea region south of 20 n which is dominated by tropical convection positive precipitation anomalies in the first and second wet periods of year 0 and negative precipitation anomalies from the fall of year 0 to the second wet period of year 1 are associated with the variation of the net energy into the atmosphere which is main

a severe drought event in northern china in winter 2008 2009 and the possible influences of la nina and tibetan plateau 1 severe drought occurred in northern china in winter 2008 09 and the la nina event might have exerted a major influence on the drought both correlation analysis and case investigation indicate that severe wintertime droughts in northern china mostly occur under la nina conditions the la nina event in 2008 2009 increased the differences in temperature and atmospheric pressure between the indo pacific oceans and the asian continent and intensified the northeasterly east asian winter monsoon flow in winter 2008 2009 the western pacific subtropical high was located farther south than normal associating with a southward shift of the intertropical convergence zone so that wet and warm flow could hardly reach northern china from the tropical oceans furthermore the la nina event in 2008 2009 strengthened the upstream portion of the upper tropospheric jet stream and the descending branch of the meridional cell over the subtropics causing a negative divergence anomaly to the northern side of the jet entrance as a result the airflow over northern china is more convergent divergent at the upper lower levels unfavorable for precipitation in winter 2008 2009 the surface and tropospheric temperatures over the tibetan plateau were above normal as a result the india burma trough was shallower and less active weakening the moisture transportation from the bay of bengal to eastern china this feature was possibly related to the less snow over the plateau results also show that both the nino3 4 sst and the tibet plateau temperature in the previous autumn can be considered indicators of the winter drought in northern china

decadal variation of summer precipitation over china and associated atmospheric circulation after the late 1990s abstractin this study the authors found that the summer precipitation over china experienced different decadal variation features from north to south after the late 1990s in northeastern and north china and the lower middle reaches of the yangtze river precipitation decreased after 1999 while precipitation experienced a significant reduction over south and southwestern china and a significant increase over the southern parts of hetao region and huaihe river valley after 2003 the authors next analyzed the associated decadal variation of the atmospheric circulation and attempted to identify the mechanisms causing the two decadal variations of precipitation the wind anomalies for the former exhibit a barotropic meridional dipole pattern with anticyclonic anomalies over mongolia to northern china and cyclonic anomalies over the southeastern chinese coast to the northwestern pacific for the latter there is a southeast northwest oriented dipole pattern in the middle and lower troposphere with cyclonic

thermal evolution of the sisters shear zone southern new zealand formation of the great south basin and onset of pacific antarctic spreading 1 the separation of zealandia from west antarctica was the final stage in the cretaceous breakup of the gondwana pacific margin continental extension resulting in formation of the great south basin and thinning of the campbell plateau leading to development of the pacific antarctic spreading ridge was partially accommodated along the sisters shear zone this east northeast striking brittle ductile structure exposed along the southeast coast of stewart island new zealand is a greenschist facies extensional shear zone that separates a hanging wall of chloritic brecciated granites and undeformed conglomerate from a footwall of mylonitic carboniferous and early cretaceous granites this complex structure exhibits bivergent kinematics and can be subdivided into a northern and southern segment the 40 ar 39 ar thermochronology indicates that cooling of the shear zone footwall began at 94 ma with accelerated cooling over the interval 89 82 ma structural and thermochronological data indicate a spatial and temporal link between the sisters shear zone initial sedimentation within the offshore great south basin extension of the campbell plateau and initiation of the pacific antarctic spreading ridge citation kula j a j tulloch t l spell m l wells and k a zanetti 2009 thermal evolution of the sisters shear zone southern new zealand formation of the great south basin and onset of pacific antarctic spreading tectonics 28 tc5015 doi 10 1029 2008tc002368