on temperature inversions and the mesospheric surf zone 1 mesospheric thermal inversions are investigated in a numerical simulation with the whole atmosphere community climate model an upward extension of the national center for atmospheric research s community climate model the seasonal character spatial extent and magnitude of the inversion layers are realistic during winter in the model the occurrence of wintertime inversions is a direct consequence of the rapid decay with height of vertically propagating planetary waves which induces large temperature perturbations in the upper mesosphere to maintain hydrostatic equilibrium the magnitude of the inversions is highly correlated with planetary wave amplitude so that large inversions develop during episodes of planetary wave amplification gravity waves do not play a major direct role in the formation of the inversions because the largest thermal tendencies associated with gravity wave breaking occur well above the range of altitudes where inversions are found however gravity waves play an essential indirect role because they set up a critical line in the upper mesosphere where rossby waves break in the mesospheric surf zone

dynamical mechanism for the increase in tropical upwelling in the lowermost tropical stratosphere during warm enso events the brewer dobson circulation strengthens in the lowermost tropical stratosphere during warm el nino southern oscillation enso events dynamical analyses using the most recent version of the whole atmosphere community climate model show that this is due mainly to anomalous forcing by orographic gravity waves which maximizes in the northern hemisphere subtropics between 18 and 22 km especially during the strongest warm enso episodes anomalies in the meridional gradient of temperature in the upper troposphere and lower stratosphere utls are produced during warm enso events accompanied by anomalies in the location and intensity of the subtropical jets this anomalous wind pattern alters the propagation and dissipation of the parameterized gravity waves which ultimately force increases in tropical upwelling in the lowermost stratosphere during cold enso events a similar signal but of opposite sign is present in the model simulations the signals in ozone and water vapor produced by enso events in the utls are also investigated

altered atmospheric responses to eastern pacific and central pacific el ninos over the north atlantic region due to stratospheric interference the two types of el nino that have been identified namely the eastern pacific ep and central pacific cp el ninos are known to exert different climatic impacts on the north atlantic region during winter here we investigate the characteristics of the teleconnection of the two el nino types with a focus on the stratosphere troposphere coupling during the ep el nino polar stratospheric warming and polar vortex weakening frequently occur with a strong tendency for downward propagation near the tropopause consequently the atmospheric pattern within the troposphere over the north atlantic sector during midwinter closely resembles the negative north atlantic oscillation pattern in contrast during cp el nino events stratospheric warming events exhibit a much weaker downward propagation tendency this difference in the stratospheric circulation response arises from the different seasonal evolution of the tropospheric wave response to the two el nino types for the ep el nino the aleutian low begins growing during december and is sustained throughout the entire winter december to february which provides favorable conditions for the continuous downward propagation of the stratospheric warming we also discuss the origin of the difference in the teleconnections from the two types of el nino associated with the distinct longitudinal position of the warm sst anomaly that determines troposphere stratosphere coupling

connection between weak stratospheric vortex events and the pacific decadal oscillation we investigate the possible impacts of the pacific decadal oscillation pdo on the occurrence of weak stratospheric polar vortex wsv events in the northern hemisphere winter wsv events which are defined when polar cap geopotential height anomalies at 50 hpa fall below the 10th percentile in winter are observed more frequently during positive pdo phases than during negative pdo phases additionally tropospheric wave forcings that drive wsv events are remarkably different between the two phases of the pdo during the positive pdo phase the vertical propagation of wavenumber one waves plays a predominant role with a rather minor contribution of wavenumber two waves this contrasts with the negative pdo phase when the wsv events are primarily caused by wavenumber two waves this difference is partly related to the pdo induced tropospheric circulation anomalies over the north pacific whose zonal wavenumber one component constructively destructively interferes with climatological planetary scale waves during positive negative pdo winters the predominant wavenumber two wave forcings during the negative pdo phase are likely related to the enhanced tropospheric eddy activity over alaska that results from the poleward shift of the pacific jet in response to the negative pdo

the el nino southern oscillation enso modoki signal in the stratosphere el nino southern oscillation enso is known to be the largest source of interannual variability in the tropical troposphere however the variability in the tropical pacific since 1979 seems to be associated not only with canonical enso events but also with a variation thereof known as enso modoki which is characterized by warm anomalies in the central pacific west from those occurring during a typical enso this works analyzes the signal of enso modoki in the stratosphere and compares it to canonical enso by using the chemistry climate whole atmosphere community climate model waccm3 5 the results reveal a significant warming in the southern hemisphere polar stratosphere during boreal winter months which propagates downward in early spring this is absent during canonical warm enso events on the other hand in the northern hemisphere stratosphere the anomalous warming typical of canonical el nino episodes during boreal winter is not statistically significant during el nino modoki events these differences are related in waccm3 5 to changes in tropical convection and tropospheric teleconnections associated with each type of event in particular an enhancement and westward displacement of the anomalous convective area during el nino modoki episodes is related to an intensification of the pacific south american teleconnection pattern and a weakening of the aleutian low during cold enso modoki events a significant anomalous cooling is present in the model simulations

initial transient response of the winter polar stratospheric vortex to idealized equatorial pacific sea surface temperature anomalies in the ncar waccm abstractperpetual winter simulations using the ncar whole atmosphere community climate model waccm are conducted to document the differences of the initial transient response of the boreal winter northern hemisphere stratospheric polar vortex to central cpw and eastern pacific warming epw events idealized patches of positive sea surface temperature sst anomalies are superimposed onto a climatological sst field to mimic canonical cpw and epw forcings a 20 member ensemble was created by varying initial atmospheric conditions for both cpw and epw cases in the ensemble average the vortex weakens under both cpw and epw forcing indicated by a negative zonal mean zonal wind tendency this tendency is mainly tied to changes in the eddy driven mean meridional circulation mmc a negative anomaly in the eddy momentum flux convergence also plays a secondary role in the weakening the vortex response however differs dramatically among individual ensemble members a few ensemble members exhibit initial

boron in chert and precambrian siliceous iron formations abstract in order to assess the importance of siliceous sediments as a sink for oceanic b and to determine the effect of diagenesis on the mobilization of b samples were analysed from chert nodules bedded cherts and siliceous banded iron formations from a variety of sedimentary environments and geologic ages boron analyses on bulk samples were made by prompt gamma neutron activation analysis the distribution of b in rocks was mapped using track methods nodular phanerozoic cherts typically contain 50 150 ppm b and bedded cherts somewhat less the b is initially concentrated in tests of silica secreting organisms but some is lost in early diagenesis as silica progressively recrystallises to quartz banded iron formation silica of archean and proterozoic age usually contains

contrasting behaviour of boron during crustal anatexis the study of volatile elements in crustal anatectic terranes may provide information about the role of fluid flow and fluid pathways during high temperature metamorphism we have studied the distribution of li and b in two migmatitic areas the pena negra anatectic complex central spain and the migmatites and leucogranites associated with the ronda peridotites southern spain they represent two contrasting cases in the behaviour of volatiles particularly b during anatexis the pena negra migmatites are dominated by diatexites where it is possible to distinguish granitic leucosomes melanosomes metric to decimetric leucogranitic segregates and decimetric to metric sillimanite rich restitic enclaves all lithologies are characterized by low b concentrations mean values 30 ppm and b is enriched in melanosomesrrestites with respect to leucosomesrleucogranites this may be due to the fact that a notable proportion of b can reside in restitic sillimanite b concentrations in leucosomes and leucogranites can be explained by closed system anatexis at ronda metatexitic and diatexitic migmatites underlie the ronda peridotites and diatexite and leucogranite dikes intrude the peridotites diatexites underlying the peridotites are characterized by cordierite q biotite garnet as ferromagne sian phases with rare or absent tourmaline low b contents 10 ppm and cordierite garnet leucosomes leucogranite dikes have high b concentrations mean valuef 400 ppm with tourmaline being a common and sometimes the most abundant ferromagnesian phase a genetic relationship between diatexites and leucogranites is strongly suggested by the presence of dikes of diatexites intruding the bottom of the peridotites we conclude that b in the leucogranites may stem from the dissolution of tourmaline originally present in the metasediments or infiltration of b rich aqueous fluids into the anatectic zone according to recent experimental work textures in some tourmaline rich ronda leucogranites suggest initial b o 23 contents in the melt higher than the present measured concentrations preliminary experimental results presented in this paper propose that this difference is not due to water activities in the melt rapid crystallization of the melts following undercooling may explain the existence of abundant euhedral tourmaline in leucogranites with low aluminium saturation index asis molar al o r caoq na oq k o and relatively low b contents q 2001 elsevier science b v all rights 23 2 2 reserved

chemical and sr isotopic variations during diagenesis of miocene siliceous sediments of the monterey formation california the monterey formation of california preserves miocene siliceous sediments at progressive generally with depth diagenetic stages diatomite opal a ct chert opai ct quartz chert for initially clay poor sediments and diatomaceous shale ct porcelanite porous opal ct quartz porcelanite for sediments that were initially clay rich the chemistry of most diatomite is controlled by three primary phases biogenic silica carbonate and detrital clay and several subsidiary phases organic material apatite pyrite and detrital minerals including quartz and plagioclase the elemental abundances of the clay poor diagenetic sequence decrease sharply with advancing diagenetic state for those elements controlled by clay al ti k rb cs fe some group b metals carbonate ca mg sr ba apatite p ca sr ba v and organics v ni while silica shows a congruent increase these first order variations reflect the initial compositions of the siliceous sediments modified by the addition of silica the removal of carbonate and apatite and the migration of petroleum during silica diagenesis anomalous abundances of mn ni cr mo and some other group b metals are associated with trapped refractory organic material and suggest that petroleum catagenesis and migration occurred during silica diagenesis migration may have been facilitated by the release of bound water during silica dehydration reactions second order variations in k rb k cs rb sr 87 sr 86 sr with advancing diagenetic state suggest ion exchange and ion expulsion by reaction of detrital phases with pore fluids diagenetic processes partially equilibrated but did not homogenize depositional 87 rb 86 sr 87 sr 86 sr mixing lines generated by detrital clays and authigenic carbonate and silica in siliceous sediments from the santa maria region however similar mixing lines in diatomites from the santa lucia area are reset to nearly horizontal slopes in associated ct porcelanites the degree of equilibration may be a function of the rate of formation of relatively impermeable quartz chert which isolated the siliceous system from further interaction with pore fluids the rapid formation of quartz chert in the santa maria region is believed to have prevented isotopic homogenization processes from reaching completion initial chemistry of the siliceous systems controlled the rates and pathways of silica diagenesis silica diagenesis in turn altered the chemistry of the siliceous sediment

geochemistry of archean shales from the pilbara supergroup western australia archean clastic sedimentary rocks are well exposed in the pilbara block of western australia shales from turbidites in the gorge creek group ca 3 4 ae and shales from the whim creek group ca 2 7 ae have been examined the gorge creek group samples characterized by muscovite quartzchlorite mineralogy are enriched in incompatible elements k th u lree by factors of about two when compared to younger archean shales from the yilgarn block alkali and alkaline earth elements are depleted in a systematic fashion according to size when compared with an estimate of archean upper crust abundances this depletion is less notable in the whim creek group such a pattern indicates the source of these rocks underwent a rather severe episode of weathering the gorge creek group also has fairly high b content 85 29 ppm which may indicate normal marine conditions during deposition rare earth element ree patterns for the pilbara samples are characterized by light ree enrichment lanybn 7 5 and no or very slight eu depletion eueu 0 82 0 99 a source comprised of about 80 felsic igneous rocks without large negative eu anomalies felsic volcanics tonalites trondhjemites and 20 mafic ultramafic volcanics is indicated by the trace element data very high abundances of cr and ni cannot be explained by any reasonable provenance model and a secondary enrichment process is called for

the boron isotope systematics of the yellowstone national park wyoming hydrothermal system a reconnaissance abstract boron concentrations and isotope compositions have been measured in fourteen hot spring waters two drill hole waters an unaltered rhyolite flow and hydrothermally altered rhyolite from the geothermal system in yellowstone national park wyoming the samples are representative of the major thermal areas within the park and span the range of fluid types for the fluids the b concentrations range from 0 043 2 69 mm kg and the 11 b values range from 9 3 to 4 4 there is no relationship between the dissolved b concentrations or isotope compositions with the concentration of any major element other than cl or physical property each basin is characterized by a restricted range in b cl ratios and 11 b values hot spring waters from the morris basin upper geyser basin calcite springs and clearwater have 11 b values close to that of unaltered rhyolite 5 2 and are interpreted to have derived their b from this source waters from mammoth hot springs sheepeater and rainbow springs have lower 11 b values close to 8 these lower values may reflect leaching of b from sedimentary rocks outside the yellowstone caldera but they are similar to the 11 b value of hydrothermally altered rhyolite 9 7 hence the light boron isotope compositions recorded in these hot spring waters may reflect leaching of previously deposited hydrothermal minerals cooler springs along the yellowstone river just outside the park boundary have lower b concentrations and higher 11 b values that may reflect mixing with shallow meteoric water

a general circulation model study of january climate anomaly patterns associated with interannual variation of equatorial pacific sea surface temperatures abstract a general circulation model has been run in the perpetual january mode to produce several long term simulations each distinguished by a different imposed equatorial pacific sea surface temperature from each of them simulations we have extracted an eight member ensemble of 90 day averaged fields ensemble mean difference maps are presented in this paper together with an estimate of the statistical significance of features which appear in thee maps these results are compared with observational studies in the literature that present difference maps of northern hemisphere winter fields composited according to some index related to the two extremes of equatorial pacific sea surface temperature variation the results show many anomaly patterns of high statistical significance that are also in good agreement with those observed in the tropics them include 990 mb wind sea level pressure and rainfall anomalies constituting the southern oscillation as well as a 200 mb height anomaly at all longitud

an examination of observed southern oscillation effects in the northern hemisphere stratosphere abstract the effects of the southern oscillation on the december february mean circulation in the northern hemisphere stratosphere were investigated using 34 years of data no evidence for a significant relation between the southern oscillation so and the zonally averaged flow is found for any region poleward of 20 n the effects of the tropical quasi biennial oscillation qbo on the zonal mean flow are much stronger and this complicates the detection of 50 effects some more suggestive results are evident when hemispheric maps of height anomalies at 50 or 30 mb are composited for the warm extremes of the 50 the present findings are broadly consistent with earlier suggestions that on average the aleutian high is intensified during the warm extremes of the southern oscillation even using the 34 years of data now available however the statistical significance of this relationship cannot be demonstrated unequivocally once again the separation of so effects from qbo influences in the limited data a

propagation of enso temperature signals into the middle atmosphere a comparison of two general circulation models and era 40 reanalysis data the vertical propagation of the el nino southern oscillation enso temperature signal has been analyzed in two general circulation models the whole atmosphere community climate model and the middle atmosphere european center hamburg model and in the era 40 reanalysis data set monthly mean data have been used and composite differences el nino la nina have been computed our results show that the enso signal propagates into the middle atmosphere by means of planetary rossby waves significant wave like anomalies are observed up to around 40 km this propagation is strongly influenced by the zonal mean zonal winds being most effective in midlatitudes of the northern hemisphere because enso events tend to peak in northern winter when stratospheric winds are westerly in the northern hemisphere and allow vertical propagation of rossby waves in addition zonal mean temperature anomalies are observed in the middle atmosphere in the tropics and at polar latitudes of the northern hemisphere these anomalies are the result of changes in the residual mean meridional circulation our analysis reveals that during an el nino event vertical wave propagation and divergence of eliassen palm flux are enhanced forcing a stronger residual circulation in the stratosphere which cools the tropics and warms the higher latitudes this pattern is highly significant in the models during certain months but much less in the era 40 data where other sources of variability in particular the quasi biennial oscillation also influence the residual circulation

response of the antarctic stratosphere to two types of el nino events this study is the first to identify a robust el nino southern oscillation enso signal in the antarctic stratosphere elninoeventsbetween1979and2009areclassifiedaseitherconventional coldtongue events positive sst anomalies in the nino 3 region or warm pool events positive sst anomalies in the nino 4 region the 40 yr ecmwf re analysis era 40 ncep and modern era retrospective analysis for research and applications merra meteorological reanalyses are used to show that the southern hemisphere stratosphere responds differently to these two types of el nino events consistent with previous studies cold tongue events do not impact temperatures in the antarctic stratosphere during warm pool el nino events the poleward extension and increased strength of the south pacific convergence zone favor an enhancement of planetary wave activity during september november on average these conditions lead to higher polar stratospheric temperatures and a weakening of the antarctic polar jet in november and december as compared with neutral enso years the phase of the quasi biennial oscillation qbo modulates the stratospheric response to warm pool el nino events the strongest planetary wave driving events are coincident with the easterly phase of the qbo

tropical sst preconditioning of the sh polar vortex during winter 2002 the response of the southern hemisphere sh polar atmosphere to the tropical sea surface temperature sst during the 2002 winter spring season is investigated by using a general circulation model gcm the sh stratospheric winter of 2002 was particularly unusual characterized by a weaker than normal polar vortex during the whole season it also registered at the end of september the first major warming yet observed in the sh this event is unexpected in the sh and it is supposed to be induced by a preconditioning of the polar vortex starting at the beginning of the winter atmospheric gcm experiments with prescribed sst boundary conditions are performed the sensitivity of the antarctic dynamics to the tropical sst of 2002 a year characterized by an el nino event of moderate intensity is studied and the uniqueness of the 2002 tropical oceanic condition is investigated through the comparison of the simulated response of the climatic system to 2002 and 1997 tropical sst 1997 being a year with a strong el nino event model results highlight a primary role played by the tropical sst of 2002 in the development of the peculiar characteristics of the antarctic dynamics during the winter months that appears to be a necessary condition for the generation of the anomalous destabilization of the polar vortex during the following spring results for june 2002 show a strong generation of vertically propagating waves resulting from the tropical sst that through the perturbation of the westerly jet at middle latitudes produces a preconditioning of the polar vortex by affecting the wave refraction index the particular structure of the tropical sst anomalies during the winter of 2002 is thought to have influenced the subsequent preconditioning of the stratospheric vortex

tropospheric precursors of anomalous northern hemisphere stratospheric polar vortices regional extratropical tropospheric variability in the north pacific and eastern europe is well correlated with variability in the northern hemisphere wintertime stratospheric polar vortex in both the ecmwf reanalysis record and in the whole atmosphere community climate model to explain this correlation the link between stratospheric vertical eliassen palm flux variability and tropospheric variability is analyzed simple reasoning shows that variability in the north pacific and eastern europe can deepen or flatten the wintertime tropospheric stationary waves and in particular its wavenumber 1 and 2 components thus providing a physical explanation for the correlation between these regions and vortex weakening these two pathways begin to weaken the upper stratospheric vortex nearly immediately with a peak influence apparent after a lag of some 20 days the influence then appears to propagate downward in time as expected from wave mean flow interaction theory these patterns are influenced by enso and october eurasian snow cover perturbations in the vortex induced by the two regions add linearly these two patterns and the quasi biennial oscillation qbo are linearly related to 40 of polar vortex variability during winter in the reanalysis record

the vertical and spatial structure of enso in the upper troposphere and lower stratosphere from gps radio occultation measurements 1 the vertical and spatial structure of the atmospheric el nino southern oscillation enso signal is investigated using radio occultation ro data from august 2006 to december 2010 due to their high vertical resolution and global coverage ro data are well suited to describe the full 3 dimensional enso structure in the troposphere and lower stratosphere we find that interannual temperature anomalies in the equatorial region show a natural decomposition into zonal mean and eddy deviations from the zonal mean components that are both related to enso consistent with previous studies we find that during the warm phase of enso zonal mean temperatures increase in the tropical troposphere and decrease in the tropical stratosphere maximum warming occurs above 8 km and the transition between warming and cooling occurs near the tropopause this zonal mean response lags sea surface temperature anomalies in the eastern equatorial pacific by 3 months the atmospheric eddy component in contrast responds rapidly within 1 month to enso forcing this signal features a low latitude dipole between the indian and pacific oceans with off equatorial maxima centered around 20 to 30 latitude in both hemispheres the eddy response pattern attains maximum amplitude in the upper troposphere near 11 km and with opposite polarity in a shallow layer near the tropopause at approximately 17 km the eddy enso signal tends to be out of phase between low and middle latitudes in both the troposphere and lower stratosphere citation scherllin pirscher b c deser s p ho c chou w randel and y h kuo 2012 the vertical and spatial structure of enso in the upper troposphere and lower stratosphere from gps radio occultation measurements geophys res lett 39 l20801 doi 10 1029 2012gl053071

tectonic evolution of the malay peninsula abstract the malay peninsula is characterised by three north south belts the western central and eastern belts based on distinct differences in stratigraphy structure magmatism geophysical signatures and geological evolution the western belt forms part of the sibumasu terrane derived from the nw australian gondwana margin in the late early permian the central and eastern belts represent the sukhothai arc constructed in the late carboniferous early permian on the margin of the indochina block derived from the gondwana margin in the early devonian this arc was then separated from indochina by back arc spreading in the permian the bentong raub suture zone forms the boundary between the sibumasu terrane western belt and sukhothai arc central and eastern belts and preserves remnants of the devonian permian main palaeo tethys ocean basin destroyed by subduction beneath the indochina block sukhothai arc which produced the permian triassic andesitic volcanism and i type granitoids observed in the central and eastern belts of the malay peninsula the collision between sibumasu and the sukhothai arc began in early triassic times and was completed by the late triassic triassic cherts turbidites and conglomerates of the semanggol formation were deposited in a fore deep basin constructed on the leading edge of sibumasu and the uplifted accretionary complex collisional crustal thickening coupled with slab break off and rising hot asthenosphere produced the main range late triassic earliest jurassic s type granitoids that intrude the western belt and bentong raub suture zone the sukhothai back arc basin opened in the early permian and collapsed and closed in the middle late triassic marine sedimentation ceased in the late triassic in the malay peninsula due to tectonic and isostatic uplift and jurassic cretaceous continental red beds form a cover sequence a significant late cretaceous tectono thermal event affected the peninsula with major faulting granitoid intrusion and re setting of palaeomagnetic signatures

extraordinary features of the planetary wave propagation during the boreal winter 2013 2014 and the zonal wave number two predominance observational features of the winter 2013 2014 are investigated using of the japanese 55 year reanalysis jra 55 data this winter can be characterized by the continuous predominance of planetary waves of zonal wavenumber two wn2 that did not cause major sudden stratospheric warming ssw events it is found that the vertical component of the eliassen palm flux of wn2 for the winter 2013 2014 is almost equal to the highest value of the winter 2008 2009 the longitudinal distribution of vertical components of plumb wave activity flux wafz for this winter shows marked downward propagation around 100 w and upward propagation around 60 e both of which are the strongest of their type among the 56 winters since 1958 1959 the convergence of wave packets propagating from around 60 e contributes to the development and continuance of the quasi barotropic aleutian high which is associated with the extension of negative extended refractive index ks region the extension of negative ks region is related to the convergence or reflection of the wave packets emanating from tropospheric blocking highs developing in the north pacific ocean the development and continuance of the quasi barotropic aleutian high is considered to be one of plausible reasons for the lack of major ssws in the winter 2013 2014 in addition to these results we revealed the significant contribution of smaller scale waves with a zonal wavenumber of three or more to the structure of localized wave packet propagation in the stratosphere

internal variability of the troposphere stratosphere coupled system simulated in a simple global circulation model internal variability of a troposphere stratosphere coupled system is investigated in a series of numerical experiments with a simple global circulation model under a perpetual winter condition in order to examine the relative importance of forced planetary waves in the interaction with the zonal mean zonal flow and baroclinic disturbances amplitude of a sinusoidal surface topography of zonal wavenumber 1 or 2 is swept as an experimental parameter 1000 day integrations are performed for 110 combinations of the external parameters intraseasonal variability of the extratropical winter stratosphere in the parameter sweep experiment of the zonal wavenumber 1 topography is classified into four regimes dependent on the topographic amplitude i a nearly radiative equilibrium state ii small undulations of the polar vortex iii intermittent breakdowns of the polar vortex or occurrence of stratospheric sudden warming events and iv a usually weak and warm state of the polar vortex the behavior of planetary waves in the stratosphere is characterized by linear propagation in regime i and by quasi linear or weakly nonlinear wave mean flow interaction in regime ii in regimes iii and iv on the other hand it is in a highly nonlinear state reflecting the occurrence of sudden warming events and the usually distorted polar vortex respectively the northern hemisphere winter stratosphere corresponds to regime iii in the intraseasonal variations while the southern counterpart is close to regime ii a lag correlation analysis shows that the dynamical linkage between the stratosphere and the troposphere is also dependent on the regimes the vertical linkage is primarily the upward control in regime i planetary waves are generated by nonlinear interaction of baroclinic disturbances in the troposphere and propagate into the stratosphere in regime ii stratospheric variations are largely confined in the stratosphere although planetary waves are generated in the troposphere the linkage in regime iii on the other hand is inevitably two way planetary wave variability has upward influence from the troposphere to the stratosphere as well as the zonal mean zonal wind shows preconditioning in the troposphere before stratospheric sudden warming events downward propagation of signals to the upper troposphere are also seen in the zonal mean temperature in high latitudes it is higher than normal at the final stage of the sequence of sudden warming events the linkage is also two way in regime iv

northern hemisphere mid winter vortex displacement and vortex split stratospheric sudden warmings influence of the madden julian oscillation and quasi biennial oscillation we investigate the connection between the equatorial madden julian oscillation mjo and different types of the northern hemisphere mid winter major stratospheric sudden warmings ssws i e vortex displacement and vortex split ssws the mjo ssw relationship for vortex split ssws is stronger than that for vortex displacement ssws as a result of the stronger and more coherent eastward propagating mjos before vortex split ssws than those before vortex displacement ssws composite analysis indicates that both the intensity and propagation features of mjo may influence the mjo related circulation pattern at high latitudes and the type of ssws a pronounced quasi biennial oscillation qbo dependence is found for vortex displacement and vortex split ssws with vortex displacement split ssws occurring preferentially in easterly westerly qbo phases the lagged composites suggest that the mjo related anomalies in the arctic are very likely initiated when the mjo related convection is active over the equatorial indian ocean around the mjo phase 3 further analysis suggests that the qbo may modulate the mjo related wave disturbances via its influence on the upper tropospheric subtropical jet as a result the mjo related circulation pattern in the arctic tends to be wave number one wave number two 25 30 days following phase 3 i e approximately phases 7 8 when the mjo related convection is active over the western pacific during easterly westerly qbo phases which resembles the circulation pattern associated with vortex displacement vortex split ssws

southern hemisphere summer mesopause responses to el nino southern oscillation abstractin the southern hemisphere sh polar region satellite observations reveal a significant upper mesosphere cooling and a lower thermosphere warming during warm enso events in december an opposite pattern is observed in the tropical mesopause region the observed upper mesosphere cooling agrees with a climate model simulation analysis of the simulation suggests that enhanced planetary wave pw dissipation in the northern hemisphere nh high latitude stratosphere during el nino strengthens the brewer dobson circulation and cools the equatorial stratosphere this increases the magnitude of the sh stratosphere meridional temperature gradient and thus causes the anomalous stratospheric easterly zonal wind and early breakdown of the sh stratospheric polar vortex the resulting perturbation to gravity wave gw filtering causes anomalous sh mesospheric eastward gw forcing and polar upwelling and cooling in addition constructive inference of enso and quasi biennial oscillation qbo could lead to st

minimal alteration of montmorillonite following long term interaction with natural alkaline groundwater implications for geological disposal of radioactive waste bentonite is one of the more safety critical components of the engineered barrier system in the disposal concepts developed for many types of radioactive waste bentonite is utilised because of its favourable properties which include plasticity swelling capacity colloid filtration low hydraulic conductivity high retardation of key radionuclides and stability in geological environments of relevance to waste disposal however bentonite is unstable under the highly alkaline conditions induced by ordinary portland cement opc initial porewater ph 13 and this has driven interest in using low alkali cements initial porewater ph9 11 as an alternative to opc to build a robust safety case for a repository for radioactive wastes it is important to have supporting natural analogue data to confirm understanding of the likely long term performance of bentonite in these lower alkali conditions in cyprus the presence of natural bentonite in association with natural alkaline groundwater permits the zones of potential bentonite alkaline water reaction to be studied as an analogy of the potential reaction between low alkali cement leachates and the bentonite buffer in the repository here the results indicate that a cation diffusion front has moved some metres into the bentonite whereas the bentonite reaction front is restricted to a few millimetres into the clay this reaction front shows minimal reaction of the bentonite volumetrically less than 1 of the bentonite with production of a palygorskite secondary phase following reaction of the primary smectites over time periods of 105 106 years

the southern oscillation part v the anomalies in the lower stratosphere of the northern hemisphere in winter and a comparison with the quasi biennial oscillation abstract the mean anomalies of 50 mb height in the northern winter for seven warm events in the southern oscillation show a weak polar vortex and an enhanced aleutian high in the mean for six cold events the polar vortex is unusually strong and the aleutian high is weakened and displaced far to the southwest these anomalies are consistent with the corresponding anomalies in sea level pressure pattern the warm events of 1963 and 1982 did not fit this pattern as in both years the polar vortex was cold and intense these events happened in years when volcanoes injected large amounts of gases and aerosols into the stratosphere and the temperature of the tropical stratosphere became unusually high in other warm events the temperature of the tropical stratosphere was abnormally low the mean anomalies of the quasi biennial oscillation for the winter as a whole west minus east phase computed from years with no cold or warm events are zonally symmetrical and shaped as four concentric regions with alternatin

influences of enso on stratospheric variability and the descent of stratospheric perturbations into the lower troposphere abstractthe linkage between el nino southern oscillation enso and north atlantic oscillation nao through the stratospheric pathway is examined using a global coupled climate model gfdl climate model version 3 cm3 with increased vertical resolution and extent in the stratosphere as compared to an earlier model gfdl climate model version 2 cm2 it is demonstrated that the relationship between enso and nao is stronger in cm3 than in cm2 it is found that enso plays an important role in modulating the frequency of occurrence of the stratospheric polar vortex anomalies through enhancement attenuation of the amplitudes of zonal wavenumbers 1 and 2 especially in late winter a higher frequency of weak strong stratospheric vortex events is simulated in cm3 during el nino la nina episodes the weak vortex events during el nino winters are preceded by enhancement of the zonal wave 1 pattern and weakening of zonal wave 2 pattern these modified tropospheric planetary waves propagate upward and then w

dynamically forced increase of tropical upwelling in the lower stratosphere drivers of upwelling in the tropical lower stratosphere are investigated using the e39c a chemistry climate model the climatological annual cycle in upwelling and its wave forcing are compared to the interim ecmwf re analysis era interim the strength in tropical upwelling and its annual cycle can be largely explainedby local resolvedwave forcing the climatological meanforcing is due to both stationaryplanetaryscale waves that originate in the tropics and extratropical transient synoptic scale waves that are refracted equatorward increases in atmospheric greenhouse gas ghg concentrations to 2050 force a year round positive trend in tropical upwelling which maximizes in the lowermost stratosphere tropical ascent is balanced by downwelling between 208 and 408 strengthening of tropical upwelling can be explained by stronger local forcing by resolved wave flux convergence which is driven in turn by processes initiated by increases in tropical sea surface temperatures ssts higher tropical ssts cause a strengthening of the subtropical jets and modification of deep convection affecting latent heat release while the former can modify wave propagation and dissipation the latter affects tropical wave generation the dominant mechanism leading to enhanced vertical wave propagation into the lower stratosphere is an upward shift of the easterly shear zone due to the strengthening and upward shift of the subtropical jets

the 6 5 day wave and its seasonal variability in the middle and upper atmosphere 1 the zonal wave number 1 planetary wave of period near 6 5 days is a robust feature in the mesosphere and lower thermosphere mlt region with prominent seasonal variability as revealed by ground based and satellite observations this wave and its seasonal variability are well reproduced in a recent one model year run of the national center for atmospheric research thermosphere ionosphere mesosphere electrodynamics general circulation model time gcm with its lower boundary specified according to the national centers for environmental prediction analysis year 1993 wavelet analysis of the model output shows that in the mlt region the wave maximizes before and after the equinoxes and minimizes at solstices the wave amplitudes at the equinoxes are smaller than the peaks before and after but are still larger than the wave amplitudes at solstices however at the lower boundary near 30 km the wave peaks are predominantly between fall and the following spring by examining the episodes of maximum and minimum wave amplitude and by conducting additional control experiments using the time gcm the structure of this planetary wave and the factors determining the wave characteristics and seasonal variability are studied in detail it is found that the wave source mean wind structure instability and the critical layers of the wave can all affect the wave response in the mlt region and can have a strong seasonal dependence before and after equinox the wave follows the waveguide and propagates from the stratosphere to the summer mesosphere mesopause where it may amplify due to baroclinic barotropic instability such instability is usually absent from the equinoctial atmosphere so that there is no wave amplification at equinox at solstice the wave decays significantly when propagating away from its winter source due to the strong eastward winter stratospheric jet in the summer side the westward jet is also strong and the meridional and vertical extension of the critical layer of the wave is large enough to enclose the instability in the summer mesosphere mesopause at middle to high latitudes the wave is thus reflected away and prevented from reaching and amplifying at the unstable region the seasonal variation of the quasi two day wave which has zonal phase speed similar to the 6 5 day wave is also studied using similar diagnostics it is further shown that within certain seasonal window periods the variability in the mlt especially the summer mlt may closely track the lower atmospheric variability associated with these waves

the signature of enso in global temperature and precipitation fields derived from the microwave sounding unit abstract global temperature anomalies associated with enso are investigated making use of a 13 year record of gridded temperature and precipitation data from the microwave sounding unit msu the warm phase of the enso cycle during this period was characterized by an overall warming of the tropical troposphere superimposed upon a distinctive equatorially symmetric dumbbell shaped pattern straddling the equator near 140 w accompanied by negative anomalies along the equator over the western pacific by means of singular value decomposition svd analysis it is shown that this pattern fluctuated in phase with the displacements of convective activity over the equatorial pacific as reflected in the anomalies in outgoing longwave radiation olr and msu precipitation fields fluctuations in mean tropical tropospheric temperature lagged the olr anomalies and the related temperature pattern by about 3 months the same dumbbell shaped pattern was evident with reversed polarity in the lower stratosphere tog

a warming tropical central pacific dries the lower stratosphere the amount of water vapor in the tropical lower stratosphere tls which has an important influence on the radiative energy budget of the climate system is modulated by the temperature variability of the tropical tropopause layer ttl the ttl temperature variability is caused by a complex combination of the stratospheric quasi biennial oscillation qbo tropospheric convective processes in the tropics and the brewer dobson circulation bdc driven by mid latitude and subtropical atmospheric waves in 2000 the tls water vapor amount exhibited a stepwise transition to a dry phase apparently caused by a change in the bdc in this study we present observational and modeling evidence that the epochal change of water vapor between the periods of 1992 2000 and 2001 2005 was also partly caused by a concurrent sea surface temperature sst warming in the tropical central pacific this sst warming cools the ttl above by enhancing the equatorial wave induced upward motion near the tropopause which consequently reduces the amount of water vapor entering the stratosphere the qbo affects the tls water vapor primarily on inter annual timescales whereas a classical el nino southern oscillation enso event has small effect on tropical mean tls water vapor because its responses are longitudinally out of phase this study suggests that the tropical central pacific sst is another driver of tls water vapor variability on inter decadal timescales and the tropical sst changes could contribute to about 30 of the step wise drop of the lower stratospheric water vapor from 1992 2000 to 2001 2005

asymmetry and nonlinearity of the influence of enso on the northern winter stratosphere 1 observations the el nino southern oscillation enso has significant effects on the extratropical stratosphere this study explores the nonlinearity and the asymmetry of these influences by distinguishing the different effects of four types of enso moderate el nino strong el nino moderate la nina and strong la nina it is revealed that the moderate el nino and the strong la nina are much more efficient than the strong el nino and the moderate la nina respectively in modulating the northern winter stratospheric variability resulting in significant nonlinearity and asymmetry the tropical rainfall anomalies induced by a moderate el nino or a strong la nina are centered over the central equatorial pacific region near the dateline while the convection responses to a strong el nino or a moderate la nina are centered farther eastward accordingly the anomalous pacific north america wave train pattern is modulated by enso in a nonlinear and asymmetric way which leads the large nonlinear and asymmetric components of the vertical eliassen palm e p flux responses to enso the increase of planetary wave activity in the extratropical stratosphere in moderate el nino winters is thus greater than in strong el nino winters whereas a strong la nina gives a larger decrease in propagation than a moderate la nina the relatively strong weak e p flux responses to moderate strong el nino and strong moderate la nina explain the remarkable nonlinearity and asymmetry in the response of the extratropical stratosphere to enso

the generation and crystallization conditions of the proterozoic harney peak leucogranite black hills south dakota usa petrologic and geochemical constraints the mineralogy petrology and geochemistry of the proterozoic harney peak granite black hills south dakota were examined in view of experimentally determined phase equilibria applicable to granitic systems in order to place constraints on the progenesis of peraluminous leucogranites and commonly associated rare element pegmatites the granite was emplaced at 3 4 kbar as multiple sills and dikes into quartz mica schists at the culmination of a regional high temperature low pressure metamorphic event principally along the periphery of the main pluton and in satellite intrusions the sills segregated into granite pegmatite couplets the major minerals include quartz k feldspar sodic plagioclase and muscovite biotite mg no molar mgo mgo feo 0 32 0 38 is the predominant ferromagnesian mineral in the granite s core whereas at the periphery of the main pluton and in the satellite intrusions tourmaline mg no 0 18 0 48 is the dominant ferromagnesian phase almandine spessartine garnet is also found in the outer intrusions there is virtually a complete overlap in the wide concentration ranges of sio2 cao mgo feo sr zr w of the biotite and tourmaline bearing granite suites with no discernable differentiation trends on harker diagrams precluding the derivation of one suite from the other by differentiation following emplacement this is consistent with the oxygen isotope compositions which are 11 5 0 6 for the biotite granites and 13 2 0 8 for the tourmaline granites suggesting derivation from different sources the concentrations of tio2 and possibly ba are higher and of mno and b are lower in the biotite granites the normative orthoclase albite ratio is extremely variable ranging from 0 26 to 1 65 in the biotite granites to 0 01 1 75 in the tourmaline granites very few sample compositions fall near the high pressure watersaturated haplogranite minima eutectic trend indicating that the granites for the most part are not minimum melts generated under conditions with a text h text 2 text o 1 instead most biotite granites are more potassic than the water saturated minima and eutectics and in analogy with experimentally produced granitic melts they are best explained by melting at 6 kbar a text h text 2 text o 1 and temperatures 800 c such high temperatures are also indicated by oxygen isotope equilibration among the constituent minerals nabelek et al 1992 several of the tourmaline granite samples contain virtually no k feldspar and have oxygen isotope equilibration temperatures 716 775 c therefore they must represent high temperature accumulations of liquidus minerals crystallized under equilibrium conditions from melts more sodic than the water saturated haplogranite minima or during fractionation of intruded melts into granite pegmatite couplets accompanied by volatile aided differentiation of the alkali elements the indicated high temperatures a text h text 2 text o 1 the relatively high tio2 and ba concentrations and the relatively low partial 18 text o values of the biotite granites suggest that they were generated by high extent biotite dehydration melting of an immature archean metasedimentary source the ascent of the hot melts may have triggered low extent muscovite dehydration melting of schists higher in the crust producing the high b low ti melts comprising the periphery of the main pluton and the satellite intrusions alternatively the different granite types may be the result of melting of a vertical section of the crust in response to the ascent of a thermal pulse with the low partial 18 text o biotite granites generated at a deeper hotter region and the high partial 18 text o tourmaline granites at a higher cooler region of the crust the low ti and high b concentrations in the high partial 18 text o melts resulted in the crystallization of tourmaline rather than biotite which promoted the observed differentiation of the melts into the granitic and pegmatitic layers found along the periphery of the main pluton and the satellite intrusions

origin of the 2016 qbo disruption and its relationship to extreme el nino events the descent of the westerly phase of the quasi biennial oscillation qbo in equatorial stratospheric zonal wind was interrupted by the development of easterlies near 40 hpa 23 km altitude in early 2016 we use tropical meteorological analyses of wind and temperature to describe in detail the special circumstances by which equatorward propagating planetary waves produced this unprecedented disruption in the qbo our findings show that the subtropical easterly jet in the winter lower stratosphere during the 2015 2016 winter was anomalously weak owing to 1 the timing of the qbo relative to the annual cycle and 2 an extreme el nino event the weak jet allowed an unusually large flux of westward momentum to propagate from the extratropical northern hemisphere to the equator near the 40 hpa level consequently the qbo westerlies at that level experienced sustained easterly acceleration from extratropical wave breaking leading to the observed wind reversal

thorium distribution in the soils of peninsular malaysia and its implications for th resource estimation abstract as the national electricity consumption peaked over the years and the reserves of fossil fuels are becoming scarce interest in thorium fuel based nuclear energy generation as an alternative energy source for malaysia is renewed this paper provides a preliminary investigation of thorium th availability in peninsular malaysia the study is based on assessment of th contents in soil indicated by massive and fertile th resources associated with granitic belts 4 series of regional on ground explorations are implemented in peninsular malaysia to obtain the baseline data of th availability the geological settings of th prospect areas and the result of statistical analyses of th data are discussed the isoconcentration mapping of th is developed and the th prospect areas in peninsular malaysia are highlighted the possibility availability production trends and economic issues of th recovery from tin by products and heavy mineral products as well as the potential of black sand placer deposit as a th resource in peninsular malaysia are also discussed

geochemistry of a chert breccia a complex history of diagenetic interactions between a siliceous sediment seawater and fresh water is revealed by intraformational chert breccias chert breccias were formed in the campanian mishash formation in israel by practically contemporaneous fracturing of lithified cherty layers followed by silicification and lithification of the matrix pairs of fragments and matrix were compared with respect to their chemical ca sr na k mg li b so4 ba and isotopic 18 o d 11 b composition 11 b was analyzed by ion probe and includes a profile across a fragment matrix contact the epicontinental cherts of the mishash fm are enriched by a factor of 10 to 50 in all elements other than o and si in comparison with deep sea cherts all results are compatible with the proposition that the lithification of the matrix occurred in contact with fresh water as opposed to seawater in which the fragments as well as most of the mishash sediments were formed the strongest evidence for this difference is in the higher concentration of b in the fragments 27 70 ppm vs 11 21ppm in the matrix and higher 18 o 29 to 35 vs 21 to 33 d is a less efficient discriminator though compatible with fresher water diagenesis of the matrix 115 to 76 for hydrogen in the chert of the fragments compared to 141 to 85 for the matrix 11 b in the matrix shows some of the lowest values recorded in sediments 11 b 33 but varies strongly suggesting that the source of boron in the matrix is a mixture of a freshwater and a marine component both seawater and the freshwater that has equilibrated with the cherts underwent varying degrees of evaporation ca sr and so4 are carried by apatite trapped as detritus in the matrix the concentration of lithium in the matrix is high 11 16 ppm whereas in the adjacent fragments it is mostly only within 1 2 ppm li probably enters the matrix from the interstitial solution during the opal 3 quartz transformation the second prolonged transformation takes place in a freshwater flow through open system this allows a much larger mass of li to be scavenged by the transforming silica despite its low concentration in freshwater copyright 2005 elsevier ltd

boron metasomatism of the alta stock contact aureole utah evidence from borates mineral chemistry and geochemistry geochemical study of the alta stock and adjacent contact aureole rocks provides information concerning the source composition and physical chemical conditions of infiltrating fluids special emphasis was given to boron b as a tracer of fluid rock interactions due to the occurrence of borate minerals ludwigite kotoite and szaibelyite in skarn deposits around the stock in addition thin section alpha track mapping implies significant b enrichments in fluid altered minerals within the stock stockwork veins and related selvages igneous sills near the stock contact skarns and in marbles up to 500 m from the stock forsterite clinohumite lizardite and malachite contain between 50 and 1200 ppm b diopside calcite clintonite phlogopite brucite hedenbergite tremolite and other minerals host b to a lesser extent aureole b enrichments correlate well with major and other trace element enrichments and support existing models of element transport in magmatic fluids with lateral down temperature flow large variations in mineral b concentrations reflect changes in b concentrations of these fluids through time mass balance calculations indicate that magmatic fluids emanating from the alta pluton could supply most b in the alta aureole it is estimated that the emplaced magma had an initial b concentration between 7 10 ppm indicated exhalative losses of b from the pluton are on the order of 50 we estimate that the exsolved fluids had a time integrated b concentration of 160 40 ppm although much higher concentrations may have attended local borate mineralization

the residual mean circulation in the tropical tropopause layer driven by tropical waves abstractlatent heating estimates derived from rainfall observations are used to construct model experiments that isolate equatorial waves forced by tropical convection from midlatitude synoptic scale waves these experiments are used to demonstrate that quasi stationary equatorial rossby waves forced by latent heating drive most of the observed residual mean upwelling across the tropopause transition layer within 15 of the equator the seasonal variation of the equatorial waves and the mean meridional upwelling that they cause is examined for two full years from 2006 to 2007 changes in equatorial rossby wave propagation through seasonally varying mean winds are the primary mechanism for producing an annual variation in the residual mean upwelling in the tropical tropopause layer averaged within 15 of the equator and between 90 and 190 hpa the annual cycle varies between a maximum upwelling of 0 4 mm s 1 during boreal winter and spring and a minimum of 0 2 mm s 1 during boreal summer this variabilit

compilation of west african mineral deposits spatial distribution and mineral endowment abstract the west african craton is highly endowed in minerals and their spatial and temporal distribution varies from single to multi phase mineralization events they are broadly related to three major tectono metallogenic elements and formed during distinct mineral epochs 1 in both archean shields kenema man and reguibat and paleoproterozoic domains baoule mossi eglab these are characterized by giant iron ore deposits that formed between ca 2 5 2 3 ga nearly all gold porphyry copper lead zinc and sedimentary manganese ore that developed between 2 2 and 2 1 ga and primary diamonds that formed between two intervals at ca 2 2 2 0 ga and in the mesozoic 2 across pan african and variscan belts these are distinguished by major precambrian iocg s copper gold that formed at ca 2 1 ga and approximately 680 ma and neoproterozoic sedimentary iron ore and phosphate deposits 3 within intracratonic and coastal basins these include the development of cenozoic lateritic bauxites over mesozoic dolerites tertiary quaternary mineral sands deposits oolitic iron ore and sedimentary phosphate deposits geological spatial and temporal correlations using the multi commodity west african mineral deposit database highlight that gold and non gold commodities formed in multiple phases this commenced in the liberian orogeny 2 9 2 8 ga with the enrichment of iron ore nickel sulphides diamonds and gold in the earth s crust the pre eburnean or tangaean eoeburnean eburnean i event yielded gold and the major eburnean orogeny yielded gold iron ore manganese diamonds magmatic nickel sulphides copper gold lead zinc and ree minerals throughout the pan african event sedimentary manganese deposits lead zinc ree minerals sedimentary phosphates and again gold were formed primary diamonds and magmatic nickel sulphides are related to the break up of gondwana followed by an intense lateritic weathering period that formed bauxite deposits along the craton margin

effect of el nino southern oscillation on the dynamical thermal and chemical structure of the middle atmosphere 1 a simulation of the middle atmosphere is presented using a general circulation model gcm forced with observed sea surface temperature for the period 1950 2000 the gcm extends to the lower thermosphere and reproduces realistic dynamical and temperature distributions the period contains several el nino and la nina events which are identified using the nino3 index composite anomalies of relevant meteorological fields are obtained by stratifying the northern winter season according to the nino3 index these anomalies have the structure of vertically propagating planetary waves extending from the troposphere to the mesosphere circulation anomalies in the middle atmosphere are accompanied by large temperature anomalies that are of opposite sign in the stratosphere and mesosphere the former being warmer and the latter colder during el nino events near the summer mesopause changes in momentum deposition by parameterized gravity waves results in warming during el nino detailed statistical analysis is used to determine the significance of these anomalies a chemical transport simulation is carried out using output from the gcm it shows that when the lower stratosphere is colder as during la nina events some ozone depletion takes place conversely when the lower stratosphere is warmer and more disturbed as is the case during el nino events heterogeneous chemical processes are inhibited

behaviour of boron in the generation of an anatectic complex the pen a negra complex central spain abstract the pe na negra anatectic complex central spain was formed from a pelitic protolith low in boron 3 80 ppm by dehydration reactions melting and fluid loss which expelled much of the boron residual b is present in sillimanite and muscovite migmatite melanosomes and restites sillimanite biotite ilmenite are relatively richer in b mean 29 ppm while the leucosomes are poorer 13 ppm late shears fractures and zones of retrograde alteration have permitted some reintroduction of b experiments demonstrated that b cannot be removed from these rocks by heating or by leaching indicating that very little is present in superficial adsorption and that the element occurs in mineral structures

the effects of the indo pacific warm pool on the stratosphere sea surface temperature sst in the indo pacific warm pool ipwp plays a key role in influencing east asian climate and even affects global scale climate change this study defines ipwp nino and ipwp nina events to represent the warm and cold phases of ipwp sst anomalies respectively and investigates the effects of these events on stratospheric circulation and temperature results from simulations forced by observed sst anomalies during ipwp nino and nina events show that the tropical lower stratosphere tends to cool during ipwp nino events and warm during ipwp nina events the responses of the northern and southern polar vortices to ipwp nino events are fairly symmetric as both vortices are significantly warmed and weakened however the responses of the two polar vortices to ipwp nina events are of opposite sign the northern polar vortex is warmed and weakened but the southern polar vortex is cooled and strengthened these features are further confirmed by composite analysis using reanalysis data a possible dynamical mechanism connecting ipwp sst to the stratosphere is suggested in which ipwp nino and nina events excite teleconnections one similar to the pacific north america pattern in the northern hemisphere and a rossby wave train in the southern hemisphere which project onto the climatological wave in the mid high latitudes intensifying the upward propagation of planetary waves into the stratosphere and in turn affecting the polar vortex

effects of the quasi biennial oscillation and stratospheric semiannual oscillation on tracer transport in the upper stratosphere usingsatelliteobservationstogetherwitha chemistry climatemodel ccm theeffect ofthestratospheric semiannual oscillation sao and quasi biennial oscillation qbo on the equatorial double peak in observed ch4 and no2 is reexamined it is concluded that the lower equatorial halogen occultation experiment haloe ch4 mixing ratio of the april double peak in 1993 and 1995 was associated with the prominent first cycle of the sao westerlies which causes local vertical downwelling in the upper equatorial stratosphere the observational evidences imply that the strong westerlies of the first cycle of the stratospheric sao in 1993 and 1995 were driven by enhanced lower stratospheric gravity wave activity in the early parts of those years the ccm simulations further verify that the gravity wave source strength has a large impact on the development and strength of the sao westerlies this result suggests that the equatorial longlived tracer mixing ratio near the stratopause which is associated with the strength of the sao westerlies was not only modulated by the qbo phase but was also significantly influenced by interannual variation in the gravity waves it is also found that the deeper equatorial trough of the double peak is unlikely to be always accompanied by the more prominent northern hemispheric lobe and the northern hemispheric lobe of the double peak can be mainly attributed to subtropical upwelling the altitude of greatest chemical destruction anomalies associated with the sao and qbo is below the trough of the double peak implying that the effect of the chemical process on the double peak is insignificant

dynamical connection between the stratospheric arctic vortex and sea surface temperatures in the north atlantic we used two long term reanalysis datasets and time slice simulations to examine the decadal relationship between the stratospheric arctic vortex sav and sea surface temperature anomalies sstas in the north atlantic and the dynamic mechanisms involved in the linkage between the two our results show that there is a significant decadal linkage between sstas over the north atlantic and the sav where warmed cooled sstas over the north atlantic in association with its principal mode correspond to a weakened strengthened sav the warmed north atlantic sstas tend to result in a weakened sav via two dynamic processes 1 constructive interference at high latitudes with a ridge in the atlantic sector and a trough in the pacific accompanied by a negative north atlantic oscillation like pattern over the north atlantic and a weakened aleutian low over the north pacific and 2 more wavenumber 1 waves propagated into the arctic stratosphere by modifying the baroclinic term of the zonal mean background state and altering the propagating conditions around the tropopause over the arctic results from reanalysis and model simulations both suggest that a strengthening wave intensity in the high latitude troposphere and more upward propagation of the planetary wavenumber 1 wave in response to the warmed north atlantic sstas conjunctly contribute to the increased planetary wave flux in the arctic stratosphere facilitating a weakened sav these results provide a new understanding of what dynamic processes control the sav and will help to predict the stratosphere on decadal timescales