linear and nonlinear runoff from large drainage basins abstract a second order standardized peak discharge distribution sspdd procedure presented in a previous paper is applied to large drainage basins with areas ranging from 450 to 8910 mi 2 1166 to 23 077 km 2 several snowmelt hydrographs appear to fit the presented distribution equally as well as rainfall hydrographs those hydrographs used in this study had runoff volumes as small as 0 001 in 0 003 cm uniformly distributed over the drainage basin like small drainage basins large drainage basins also exhibit linear and nonlinear runoff characteristics

the role of bay of bengal convection in the onset of the 1998 south china sea summer monsoon abstract assimilated analysis fields from the south china sea monsoon experiment and the outgoing longwave radiation data from the national center for atmospheric research ncar have been employed to describe the large scale and synoptic features of the subtropical circulation during the bay of bengal bob 6 20 n 80 100 e and south china sea scs 7 20 n 110 120 e monsoon onsets in 1998 the results show that the asian monsoon onset during may 1998 exhibited a typical eastward development from the bob region to the scs domain the weakening and retreat of the subtropical anticyclone from the scs were preceded by the intrusion of westerlies and the development of convective activities over the northern part of the scs nscs 15 20 n 110 120 e as the vertical shear of zonal wind changes in sign the ridge surface of the subtropical anticyclone tilted northward and the summer pattern was established over the scs based on these observational results version 4 of the ncar climate model ccm3

comment on helium isotope fluxes and groundwater ages in the dogger aquifer paris basin by b marty t torgersen v meynier r k o nions and g de marsily

how does the south asian high influence extreme precipitation over eastern china based on the high resolution observed daily precipitation data three characteristic regions over eastern china are first defined through the rotated empirical orthogonal function then the relationship between summer june july august extreme precipitation across the three characteristic regions of eastern china and the south asian high sah is examined to determine how the northwest southeast movement and area magnitude of sah influence the summer extreme precipitation across eastern china when the south asian high is located anomalously northwest there is more extreme precipitation over the northern part of eastern china but less extreme precipitation over the jiang huai river basin when the sah intensifies there is more extreme precipitation over the jiang huai river basin the mechanisms are that under the conditions of anomalously northwestward displacements the positive geopotential anomalies over central asia induce a deep barotropic korean high through a rossby wave train resulting in more water vapor transportation to eastern china with more convergence over the northern part of eastern china located at the northwestern edge of the korean high but with a divergence over the jiang huai river basin when the sah intensifies accompanied by an enhanced and westward extended western pacific subtropical high the convergence over the jiang huai river basin increases with enhanced water vapor transportation due to the confluence of warm and cold advections these mechanisms are achieved through shifts toward the high tail low tail of the daily precipitation cumulative distributions of these two regions and finally increases decreases in the occurrence of extreme precipitation

helium 3 anomalies and crust mantle interaction in italy abstract the distribution of primordial 3he in the crust of italy has been investigated through a survey of groundwaters hot springs exploration and production geothermal wells the mantle derived component varies from 0 to 60 and reaches a maximum at vulcano in the eolian islands 3he anomalies occur where the conductive heat flow is relatively high but the relationships between heat flow and anomaly are uncertain the distribution of 3he in the main reservoir and cap rock to the larderello geothermal system shows that the mantle derived 3he varies from 5 to 40 of total he and reaches a maximum in fluids extracted from a depth of ca 3 km within the basement bomb produced tritiogenic 3he appears to make a near negligible contribution well 107 at larderello has been monitored over a period of 17 months and the 3 he 4 he ratio r varies from 1 4 to 1 6 times the atmospheric ratio ra whilst he ne varies from 9 to 160 a model is proposed for the larderello geothermal system whereby mantle derived heat and volatiles are advected to shallow 6 8 km depths in association with melts and released into the main geothermal reservoir at larderello in a non uniform manner possibly associated with fracturing isotopic and elemental equilibrium of gaseous species c o h appears to have taken place in the basement to the main reservoir from where fluid with r ra 3 2 has been extracted

understanding and modelling dissolved gas transport in the bedrock of three fennoscandian sites summary the origin and transport of dissolved gases in the geosphere is of interest for assessment studies of nuclear waste repositories in this paper we analyse available field measurements of helium methane and hydrogen at three fennoscandian sites forsmark and laxemar in sweden and olkiluoto in finland the field data are interpreted using different analytical models all based on the one dimensional diffusion equation the results of the different models provide estimates about the amount of deep gas flux the in situ production and the groundwater residence time of the considered sites the computed helium fluxes which fall within the lower range of crustal degassing fluxes reported by torgersen 2010 are strictly related with the high tightness of the considered fracture media the very high estimates of groundwater residence time indicate that at the considered depths there are only very few flowing fractures while in the rest of the fractured domain groundwater has been almost motionless during a whole glacial cycle

spring land surface and subsurface temperature anomalies and subsequent downstream late spring summer droughts floods in north america and east asia author s xue y diallo i li w david neelin j chu pc vasic r guo w li q robinson da zhu y fu c oaida cm abstract 2018 american geophysical union all rights reserved sea surface temperature sst variability has been shown to have predictive value for land precipitation although ssts are unable to fully predict intraseasonal to interannual hydrologic extremes the possible remote effects of large scale land surface temperature lst and subsurface temperature subt anomalies in geographical areas upstream and closer to the areas of drought flood have largely been ignored here evidence from climate observations and model simulations addresses these effects evaluation of observational data using maximum covariance analysis identifies significant correlations between springtime 2 m air temperature t2 m cold warm anomalies in both the western u s and the tibetan plateau and downstream drought flood events in late spring summer to support these observational findings climate models are used in sensitivity studies in which initial lst subt anomaly is imposed to produce observed t2 m anomaly to demonstrate a causal relationship for two important cases between spring warm t2 m lst subt anomalies in western u s and the extraordinary 2015 flood in southern great plains and adjacent regions and between spring cold t2 m lst subt anomalies in the tibetan plateau and the severe 2003 drought south of the yangtze river region the lst subt downstream effects in north america are associated with a large scale atmospheric stationary wave extending eastward from the lst subt anomaly region the effects of sst in these cases are also tested and compared with the lst subt effects these results suggest that consideration of lst subt anomalies has the potential to add value to intraseasonal prediction of dry and wet conditions especially extreme drought flood events the results suggest the importance of developing land data and models capable of preserving observed soil memory

some characteristics and implications of drainage basin linearity and non linearity abstract drainage basin hydrologic linearity is defined as the condition that exists on a drainage basin when runoff volume is directly proportional to precipitation volume hydrologic nonlinearity exists when runoff volume is not directly proportional to precipitation volume drainage basin linearity is indicated when the slope of the mathematical linear equation describing the second order standardized peak discharge distribution sspdd is 1 00 or nearly so nonlinear drainage basins show the same slope to be less than 1 00 the degree of nonlinearity is determined by the magnitude of this negative slope serious errors over estimating discharge can result when a drainage basin is assumed to be linear when in fact it is nonlinear a probable relation exists between the slope of the sspdd and the slope of the discharge probability curve

two interannual dominant modes of the south asian high in may and their linkage to the tropical sst anomalies the variations of the intensity and position of the south asian high sah in may are critical for the interannual change in the asian summer monsoon onset process the present work has defined two dominant modes of the sah in may via the principal component analysis of sah s strength zonal extension and ridgeline position indices during 1979 2015 the first mode sah intensity mode features a coherent enhancement of the sah strength and zonal extension while the second mode sah position mode exhibits a meridional swing of the sah ridgeline both diagnosis analysis and numerical experiments validate that the distinct evolution of enso in boreal spring determines its different influences on the two modes when an el nino decays quickly during march may its resultant warm anomalies of sea surface temperature sst in the tropical indian ocean can affect the sah intensity mode by modifying the tropical convection over the southwestern bay of bengal acting as a local sst forcing to the circulation however the sah position mode depends on the persistence of the enso event during boreal spring the remote el nino related sst forcing can enhance the large scale descent over the indo pacific ocean which suppresses the tropical convection to modify the mid upper level thermal structure over south asia inducing the interannual variation of the sah ridgeline in may

synoptic scale characteristics and atmospheric controls of summer heat waves in china summer heat waves with persistent extreme high temperatures have been occurring with increasing frequency in recent decades these extreme events have disastrous consequences for human health economies and ecosystems in this study we examine three summers with intense and protracted heat waves the summers of 2003 2006 and 2013 with high temperatures located mainly in southeastern southwestern and eastern china respectively the synoptic scale characteristics of these heat waves and associated atmospheric circulation anomalies are investigated in the early heat wave episode of 2003 a heat center was located in the southeast coastal provinces during the first 20 days of july the maximum southward displacement of the east asian jet stream eajs induced anticyclonic anomalies to the south associated with southwestward intensification of the western north pacific subtropical high wnpsh and extreme high temperatures were found only to the south of the yangtze river in the later episode a poleward displacement of the eajs and an enhanced wnpsh over the midlatitudes of eastern china resulted in a heat dome over the region and the heat wave extended northward to cover a larger area of eastern china the coupling between the westward enhanced wnpsh and poleward displaced eajs was found in the east china heat wave of 2013 as well but the area of high temperatures reached far to the north in august 2013 with below normal temperatures located in a small region of south china in the 2006 southwestern drought and heat wave extreme poleward displacement of the eajs associated with extraordinary westward extension of the wnsph resulted in further blocking of the moisture supply from the southwest monsoon large scale moisture deficiencies dry conditions and downslope winds were common features of all investigated heat wave episodes but in 2006 low level heat lows associated with a well mixed layer due to intensive daytime heating and atmospheric turbulence were emphasized

noble gases in crude oils from the paris basin france implications for the origin of fluids and constraints on oil water gas interactions in order to investigate the potential of noble gases to trace the dynamics of oil reservoirs we have analysed the abundance and isotopic composition of all noble gases he ne ar kr and xe in crude oils from the paris basin france using a new extraction and purification procedure the main oil reservoirs are presently located in the jurassic dogger limestone and in the triassic keuper sandstone but hydrocarbons originated from a common source rock formation located in the interbedded liassic sequence despite this common origin the abundance and isotopic ratios of the noble gases differ between the dogger and the keuper the isotopic compositions of kr and xe are indistinguishable from that of air 3he 4he ratios higher than those predicted from radiogenic production in the sediments or in the crust are attributed to the occurrence of mantle derived 3he in the basin each sedimentary sequence is characterised by well defined and homogeneous 21ne 22ne and 40ar 36ar ratios which average 0 0306 0 0008 and 312 10 for the dogger and 0 0367 0 0012 and 664 30 for the keuper respectively the main source of radiogenic noble gases appears to be the continental crust underlying the basin with possible regional contributions of noble gas isotopes produced in the sediments the helium and argon isotopic ratios of the dogger oils are very similar to those observed in geothermal waters flowing in the dogger aquifer throughout the basin demonstrating that noble gases in oils derive from associated groundwaters oil reservoirs in the paris basin therefore accumulate noble gases from wide regions of the continental crust through cross formational flow of groundwaters and subsequent partitioning into oil this observation implies that noble gases cannot be directly used to date oils but can provide time constraints if 1 water oil interactions are quantified and 2 the residence time as well as the noble gas characteristics of associated groundwaters are known oil water gas partitioning processes are well recorded in the fractionation of noble gas elemental abundance two distinct processes have been identified 1 accumulation of atmosphere derived ang and radiogenic noble gases both initially dissolved in groundwaters resulting in a positive correlation between absolute amount of ang and the extent of heavy noble gas fractionation and 2 subsequent fractional degassing resulting in a negative correlation between ang abundance and heavy noble gas fractionation degassing is particularly evident for the keuper oils and might have occurred in the reservoirs following hydrodynamic gas stripping the ang abundance in the dogger reservoirs requires that about one order of magnitude more water than presently observed has interacted with the oil given current estimates of the residence time for groundwaters in the dogger aquifer the duration of oil water interaction is in qualitative agreement with a palaeocene oligocene age for the major episode of secondary oil migration in the paris basin high xenon contents in keuper reservoirs suggest that they have experienced hydrodynamic interactions between flowing waters and oils for long time and that the trias might have reached hydrostatic condition only recently

mechanisms for concurrent low latitude circulation anomalies responsible for persistent extreme precipitation in the yangtze river valley concurrent position shifts of the mid level western pacific subtropical high wpsh and the upper level south asia high sah are regarded as significant precursors for persistent extreme precipitation events pepes in the yangtze river valley yrv by performing composite analyses accountable vorticity genesis and dissipation are diagnosed based on a potential vorticity diabatic heating theory the results indicate that about 1 week preceding precipitation onset a wave like pattern of anomalous diabatic heating q initiates its northwestward propagation from equatorial central pacific subsequently this wave like pattern induces substantial changes in both horizontal and vertical structure of local q along the propagating route forced negative vorticities in key areas result in the zonal approach between the sah and the wpsh during pepes two thermal induced vertical circulation cells take shape with common strong ascent centered in the yrv these anomalous cells are capable of self maintaining for a few days via positive feedback processes the wpsh and the sah are therefore anchored in respective favorable positions for pepes simultaneously descending motion of these two cells increases local solar radiation and decreases upward latent heat flux from surface facilitating warmer underlying surface and swift accumulation of lower level moisture correspondingly enhanced heating to the north and rapid developing cyclone over warmer sea surface to the south combine to terminate above positive feedback processes finally both the wpsh and the sah retreat to their normal positions accompanied by a quick decay of pepes

the isotopic composition of radiogenic helium and its use to study groundwater movement in confined aquifers abstract the 3 he 4 he ratio for radiogenic he is shown to be primarily determined by the abundance of li and neutron absorbing elements in the host formations and is almost independent of the radioelement abundance the 3 he 4 he ratios have been computed for various li contents in rock matrices with average abundances of other elements the 3 he 4 he ratio is specific for each formation and may therefore be used to study crustal diffusion of he it is shown however that both the 3he and 4he contents of continental basements are likely to exceed those of the mantle so that diffusion of mantle he through continental crust is not likely to occur changes in the 3 he 4 he ratio for dissolved he have potential for studying groundwater movement and mixing processes atmospheric he which was dissolved at recharge is progressively diluted by radiogenic he with an isotopic ratio characteristic of the aquifer as the groundwater migrates down dip mixing proportions for formation he and atmospheric he in aquifers for which there is admixture of fracture borne water and interstitially stored water can also be estimated from isotopic measurements these processes are discussed in relation to two aquifers in eastern england

condensation heating of the asian summer monsoon and the subtropical anticyclone in the eastern hemisphere the effects of condensation heating on the formation of the subtropical anticyclone in the eastern hemisphere eh are studied by means of theoretical analysis and numerical simulation the complete vorticity equation is employed for the analysis it is found that due to the vertical gradient of strong condensation heating the distribution of cyclone and anticyclone in the upper troposphere is out of phase with that in the middle and lower troposphere this is confirmed by a series of numerical experiments the horizontal gradient of the condensation heating also affects the configuration of the subtropical anticyclone it is concluded that condensation heating is a key factor for the formation and location of the summer subtropical anticyclone in the eh the latent heating released by the asian monsoon rainfall contributes to the formation of the 200 hpa south asian anticyclone on the western side of the heating center and the 500 hpa western pacific subtropical anticyclone on the eastern side of the center such configurations are modified to some extent by surface sensible heating and orography the circulation in mid latitudes is also affected by the latent heating in the subtropical area through the propagation of rossby waves

effect of the arakan mountains in the northwestern indochina peninsula on the late may asian monsoon transition by simulations using a global climate model with and without the arakan mountains in the northwest of myanmar we demonstrated that this mesoscale meridionally elongated mountain range has a substantial effect on anchoring and enhancing precipitation in the region during the bay of bengal bob monsoon onset in late may in this period the presence of the arakan mountains in the model significantly improves the simulation of the thermal and dynamical atmospheric structure of the monsoon by substantially enhancing precipitation deepening the midtropospheric trough and the southwesterly flow over the bob and strengthening the upper tropospheric anticyclone atop the trough these mountain induced changes essentially improve the simulation of the late may asian summer monsoon transition prior to the bob monsoon onset the blocking and deflecting effects of the arakan mountains on the low level flow are marked which enhance the moisture convergence and also probably influence the oceanic forcing over the bob as well as the mountain effect on the moisture convergence inclusion of the arakan mountains apparently initiates an upstream troughing effect which in turn enhances the synoptic and large scale circulation during the monsoon transition furthermore the presence of the arakan mountains induces a large scale wavelike perturbation which likely leads to an improvement of meiyu baiu simulation this study reveals that a narrow mountain like the arakan mountains likely contributes markedly to the characteristics of the asian summer monsoon during its early seasonal march such effects need to be reasonably resolved in the models

helium accumulation in groundwater ii a model for the accumulation of the crustal 4he degassing flux abstract a model of 4 he accumulation in a confined aquifer is presented which includes in situ production and a crustal degassing flux of 4 he into the bottom of a confined aquifer the model is consistent with the measurements of 4 he concentration in the great artesian basin australia torgersen and clarke 1985 and also with the measurements of 4 he concentration in the auob sandstone of namibia heaton 1981 the measured value of the crustal degassing flux of 4 he from these two areas is comparable with the 4 he degassing flux calculated from the atmospheric budget of 4 he wasserburg et al 1963 ozima and podosek 1983 a literature review suggests that a crustal degassing 4 he source may account for the 4 he accumulation in many other groundwater systems it is concluded from the literature review the detailed modelling of 4 he accumulation in gab and the auob sandstone and the atmospheric budget that crustal degassing of 4 he may be a common and widespread phenomena

etude geochimique de la nappe du dogger du bassin parisien abstract waters from the dogger nappe of the paris basin which are utilized for heating have a chlorinity in the range 0 07 0 6 mole litre and a temperature in the range 48 80 c we present here a geochemical study of waters sampled in about 25 boreholes except chloride and sulfates elements seem to be controlled by equilibrium with minerals commonly encountered in hydrothermal systems calcite disordered dolomite chalcedony ca montmorillonite disordered kaolinite albite and adularia a chalcedony geothermometer indicates temperatures close to the observed temperatures whereas the na k geothermometer gives a mean value close to the mean observed temperature but na k variations do not follow local variations of temperature the cl br ratio 420 suggests that the chlorinity of dogger water is related to sea water dogger water can be the result of interaction between a mixture of evolved sea water and fresh water and minerals of the reservoir

radiogenic helium in shallow groundwater within a clay till southwestern ontario 1 profiles of 4he in pore water were measured in clay aquitards in sw ontario the 4he distributions are consistent with groundwater velocities that are 70 of initial 4he for 50 to 60 ka prior to incorporation into the till

location and variation of the summertime upper troposphere temperature maximum over south asia the upper troposphere temperature maximum uttm over south asia is a pronounced feature in the northern hemisphere summer its formation mechanism is still unclear this study shows that the latitude location of the upper tropospheric warm center t coincides with the subtropical anticyclone and its longitude location is determined by the zonal distribution of vertical gradient of heating cooling q z q z which is different from the gill s model since both convective heating and radiation cooling decrease with height in the upper troposphere the heating cooling generates vertical northerly southerly shear leading to a warm cold center being developed between heating in the east west and cooling in the west east the location of the uttm coincides with the south asian high sah and is between a radiation cooling in the west and the asian monsoon convection heating source in the east the uttm is sensitive to this convective heating increased heating in the source region in a general circulation model causes intensification of both the sah and uttm and imposing periodic convective heating there results in oscillations in the sah uttm and vertical motion to the west with the same period diagnoses of reanalysis indicate that such an inherent subtropical t q z relation is significant at interannual timescale during the end of the twentieth century rainfall increase over south china is accompanied by an increasing northerly flow aloft and intensification in the sah and uttm to the west results demonstrate that the feedback of atmospheric circulation to rainfall anomalies is an important contributor to the regional climate anomaly pattern

asian summer monsoon onset barrier and its formation mechanism the onset process of asian summer monsoon asm is investigated based on diagnostic analysis of observations of precipitation and synoptic circulation results show that after the asm commences over the eastern bay of bengal bob around early may the onset can propagate eastwards towards the south china sea and western pacific but is blocked on its westward propagation along the eastern coast of india this blocking termed the monsoon onset barrier mob presents a gill type circulation response to the latent heating released by bob monsoon convection this convective condensation heating generates summertime wintertime vertical easterly westerly shear to its east west and facilitates air ascent descent the convection then propagates eastward but gets trapped on its westward path to the east of the central bob the surface air temperature sat cools faster than the underlying sea surface temperature sst due to monsoon onset thus more sensible heat flux supports the onset convection to propagate eastward to the west of the central bob however the land surface sensible heating over the indian peninsula is strengthened by the enhanced anticyclone circulation and air descent induced by the bob monsoon heating the strengthened upstream warm horizontal advection then produces a warm sat center over the mob region which together with the in situ cooled sst reduces the surface sensible heating and atmospheric available potential energy to prevent the occurrence of free convection therefore it is the change in both large scale circulation and air sea interaction due to bob summer monsoon onset that contributes to the mob formation

possible impacts of mega el nino southern oscillation and atlantic multidecadal oscillation on eurasian heatwave frequency variability identifying predictability sources of heatwave variations is a scientific challenge and of practical importance this study investigates the summertime heatwave frequency hwf over eurasia for 1950 2014 the eurasian hwf is dominated by two distinct modes the interdecadal id mode featured by an increasing pattern overall centred around eastern europe central asia and mongolia southwestern china and the interannual ia mode resembling a tripole anomaly pattern with three centres over western northern europe northeastern asia and east asia the id mode is found to be influenced by mega el nino southern oscillation mega enso and the atlantic multidecadal oscillation amo and the latter has far more effect whereas the ia mode is connected with mega enso further analysis suggests that mega enso variations can incite a gill type response spreading to eurasia while the amo changes cause eastward propagating rossby wave trains toward eurasia these two teleconnection patterns together contribute to the large scale circulation anomalies of the id mode and those related to the ia mode arise from the teleconnection pattern excited by mega enso a strong mega enso triggers subsidence with high pressure anomalies warms the surface and increases the hwf significantly over northeastern asia particularly likewise the warm amo induced circulation anomalies engender surface radiative heating and hwf growth in most of the eurasian continent except some localized siberian and asian regions the situation is opposite for a weak mega enso and amo those models from phase 5 of the coupled model intercomparison project cmip5 which realistically capture the features of the id mode can reproduce the amo like sea surface temperature anomalies sstas while signals resembling mega enso are found in those with favourable capability of simulating the ia mode on the contrary these relevant sstas linked to the respective modes vanish in the models with little skills thus mega enso and the amo might provide two critical predictability sources for heat waves over eurasia

characteristics and mechanisms of the subseasonal eastward extension of the south asian high abstractthis study investigates the features of eastward extension of the south asian high sah and its connection with diabatic heating and rainfall over eastern asia on subseasonal time scales the causes of sah s eastward extension are examined by potential vorticity pv diagnosis with emphasis on the joint role of diabatic heating feedback and midlatitude wave train the sah s eastward extension features eastward propagation of a wave train across eurasia among the wave train the migration of weak high from the western flank of the tibetan plateau tp to the east of tp contributes to the sah s eastward extension at the early stage when the sah approaches its easternmost position a strong negative pv positive geopotential height center prevails to the east of the tp at 200 hpa the associated anomalies in diabatic heating and rainfall include the anomalous heating and above normal rainfall over the south china sea scs and subtropical western pacific occurring 12 days before the sah s eastern

connection between anomalous zonal activities of the south asian high and eurasian summer climate anomalies abstractusing the daily mean anomalies of atmospheric variables from the ncep reanalysis 1 ncep r1 this study reveals the connection between anomalous zonal activities of the south asian high sah and eurasian climate anomalies in boreal summer an analysis of variance identifies two major domains with larger geopotential height variability located in the eastern and western flanks of the sah at around 100 and 150 hpa respectively for both eastern and western domains extreme events are selected during 1981 2014 when normalized height anomalies are greater than 1 0 less than 1 0 standard deviation for at least 10 consecutive days based on these events four sah modes that include strong and weak tibetan modes stm and wtm respectively and strong and weak iranian modes sim and wim respectively are defined to depict the zonal sah features the positive composite in the eastern western domain indicates the stm sim manifests a robust wavelike pattern with an anomalous low at 150 hpa and su

summertime quadruplet heating pattern in the subtropics and the associated atmospheric circulation 1 a quadruple heating pattern is found over each subtropical continent and its adjacent oceans in summer based on data diagnosis the ocean region to the west is characterized by strong longwave radiative cooling lo the western and eastern portions of the continent are dominated by sensible heating se and condensation heating co respectively and the ocean region to the east is characterized by double dominant heating d with lo prevailing co these compose a losecod heating quadruplet its general feature is heating over the continent and cooling over the oceans a distinct circulation pattern accompanies this heating pattern in the upper troposphere anticyclonic circulation over the continent is accompanied by cyclonic circulations over the oceans on its western and eastern sides near the surface cyclonic circulation over the continent is accompanied by anticyclonic circulations over the oceans on both sides this circulation feature is interpreted as the atmospheric thermal adaptation to the quadruplet heating it is further demonstrated that the global summer subtropical heating and circulation may be viewed as mosaics of such a quadruplet heating and circulation patterns respectively

role of the tibetan plateau thermal forcing in the summer climate patterns over subtropical asia the mechanism of the tibetan plateau tp thermal forcing in influencing the summer climate patterns over subtropical asia is investigated by means of ncep ncar reanalysis diagnosis results show that since the tp is a huge elevated heating source with the strongest heating in the surface layers in summer the thermal adaptation results in a shallow cyclonic circulation near the surface and a deep anticyclonic circulation above it according to the steady barotropic vorticity equation for large scales airflow must converge in the lower layers and diverge in the higher layers over the eastern side of the tp however the western side of the tp is characterized by a reversed structure i e divergence in lower layers but convergence in higher layers hence pumping and sucking processes bring in upward and downward movement over the east and west sides of the tp respectively such a circulation is embedded in the large scale circulation that is forced by the eurasian continental heating because the tp together with iran plateau are located at the central and eastern parts of the continent and because the orography induced circulation is in phase with the continental scale circulation the role of the tp thermal forcing is to intensify the east asian monsoon to its east and the dry and hot desert climate in mid asia to its west the summertime thermal forcing of the rockies and andes can generate similar circulations along the two subtopics as the tp does since they are located near the western coasts but the lower troposphere poleward flow that is induced by orographic thermal forcing does not coincide with the poleward flows over the eastern coastal region that is induced by continental heating and the monsoon rainfall in north and south america is not as strong as in east asia however the equatorward flow and the associated subsidence induced by the two mountain ranges along the western coasts of both north and south america are in phase with those induced by continental heating these contribute to the formation of the stable low stratus clouds and strong long wave radiative cooling over the eastern subtropical pacific regions just off the western coast of the continent

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

sulphur and oxygen isotopes of dissolved sulphur species in formation waters from the dogger geothermal aquifer paris basin france isotopic analyses of the s in sulphides and sulphates from formation waters were made at 35 geothermal wells exploiting the dogger geothermal aquifer of the paris basin isotopic analyses of the o of the dissolved sulphates were also made on 12 of these the results show a distribution of the 34s of the sulphates according to geographic zones that also correspond to variations in the geochemistry of the fluids in particular the sulphide content samples taken in the seine st denis area and in the areas north and west of paris show high 34s values ranging from 26 3 to 48 9 values of 34s for sulphides range from 8 5 to 5 and are interpreted as reflecting the effect of bacterial reduction in a confined part of the basin modelling this reduction by a rayleigh distillation mechanism made it possible to calculate a value of 1 038 0 003 for the coefficient of fractionation between the sulphates and sulphides we show that an important part of the sulphides formed by bacterial reduction has been subtracted from the fluid by deposition south of paris and in the val de marne the 34s values for the sulphates are more uniform ranging between 22 4 and 26 6 despite the existence of bacterial activity this is most probably due to a higher rate of flow of the waters entailing renewal of the sulphate stock the isotopic composition of the o of the sulphates for the seine st denis area and the areas west and north of paris is very uniform between 16 1 and 17 1 despite the wide range in 34s 26 3 to 48 9 for the same samples the calculated isotopic temperatures are close to those measured in situ these results suggest either that sulphate water isotopic equilibrium was established after the reduction or that the coefficient of o fractionation is very low 1 003 during bacterial reduction

thermal evolution of the intracratonic paris basin insights from 3d basin modelling abstract the thermal evolution of the paris basin pb has been widely studied using 1d 2d and more rarely 3d thermal models it is well documented that the pb experienced higher temperatures in the past compared to what is currently observed however a quantitative analysis of the main processes and parameters that affect the temperature distribution at the basin scale and over time is still not available in this study through basin modeling which accounts for the main processes of the thermal evolution of sedimentary basins we analyze and quantify the role of the different geological mechanisms by discriminating the causes of abnormal temperatures during the late mesozoic this is done with a 3d basin model built from base moho to present day topography using the temisflow basin modelling software the model includes thermal processes within an evolving upper crust defined by three main structural domains each crustal sector presents radiogenic heat production conductivity and thickness values which are used as input parameters to reproduce the paleo and present day basal heat flow variations observed in the basin the model calculates heat flow through time in both crust and sedimentary column where the crust is coupled with the geological evolution of the basin this approach allows estimating the eroded thickness during the main tertiary uplift event and therefore the maximum temperature in the late cretaceous the model is constrained by different types of paleo thermo chronometers and by 52 wells that are regionally distributed over the entire basin resulting in a new regional thermal history of the pb the amount of missing section in the cretaceous chalk which mainly affected the eastern part of the basin is increased by up to 500m compared with previous studies and constitutes the key controlling factor of the temperature evolution this new regional thermal history of the paris basin may be important for further analysis of the hc generation from the lower jurassic toarcian source rock and bring new insights into the geothermal potential of the basin

chlorine 36 dating of very old groundwater 1 the great artesian basin australia chlorine 36 has many advantages as a dating tool for very old groundwater these advantages include a suitable half life 3 01 x 10 sup 5 years simple geochemistry conservative behavior in groundwater and a general absence of subsurface sources at levels comparable to the atmospheric input recent advances in tandem accelerator mass spectrometry have permitted the analysis of sup 36 cl at low abundance expected following residence in the subsurface for 10 sup 6 years or more in order to test the suitability of sup 36 cl for dating very old groundwater the sup 36 cl cl ratios of 26 groundwater samples from the great artesian basin of australia have been measured groundwater ages calculated from the sup 36 cl data compare favorably with ages computed independently from hydrodynamic simulations

crustal helium in deep pacific waters we have analyzed deep helium isotope data from world ocean circulation experiment section p17 along 135 w in the pacific ocean combining these data with neon data we have derived the isotopic ratio rt of the nonatmospheric part of helium terrigenic helium the calculated rt values are significantly lower than helium isotope ratios from mid ocean ridge mor sources rmor 8ra ra 3he 4he air which are generally presumed to dominate the isotope characteristics of helium of nonatmospheric origin for the depths most influenced by the southern east pacific rise epr helium plume the isotopic ratio of terrigenic helium is 7 4 ra however both the northern epr plume and the juan de fuca ridge jdfr plume show significantly lower rt values of 6 8 ra we find minimum rt values of 5 6 ra at about 20 n to 30 n from 2000 m depth to the ocean floor we conclude that in addition to the epr and jdfr helium sources having mor isotope characteristics there is a flux of radiogenic 4he out of deep sea sediments and the oceanic crust which causes a significant deviation of rt toward values lower than rmor using our calculated terrigenic 4he concentrations and isotope ratios rt and the helium isotope ratios of the two end members mor helium and crustal helium we derive concentrations and ocean bottom fluxes of crustal 4he 4hecrust maximum concentrations of 4hecrust up to 30 pmol kg 1 are found at about 20 n to 30 n between 2000 m and 4000 m along the p17 section the mean crustal 4he flux is obtained as 1 0 0 4 109 atoms m 2earth s 1

a possible precursor of the south china sea summer monsoon onset effect of the south asian high in climatology the south china sea scs summer monsoon scssm generally onsets in pentad 28 16 20 may the eastward extension of the south asian high into the scs in pentad 27 is a possible precursor to the scssm onset in the upper troposphere the south asian high sah warms the air by inducing the positive potential vorticity advection which strengthens precipitation over the southern scs when local convection becomes strong enough to decrease the vertical temperature gradient in pentads 28 29 the upper level warming center overlies the subcloud warm region over the scs to satisfy the requirement of the angular momentum conservation a cross equatorial flow then forms together with strong vertical easterly wind shear and deep monsoon convection over the scs marking the full establishment of the scssm the abrupt change in the sah in may could therefore be an early indicator of the onset of the scssm

a study of drainage basin linearity and non linearity abstract standardized peak discharge distribution is defined as the log of peak discharge regressed on log runoff volume the first order fspdd and the second order sspdd standardized peak discharge distributions are obtained by replacing the dependent variable of the original distribution with the log of peak discharge divided by runoff volume and by runoff volume squared respectively the distributions were developed in the u s a and the slope of the sspdd was proposed as a criterion indicating drainage basin hydrologic non linearity for testing the distributions applicability to other localities investigating some rainfall runoff linearity and non linearity characteristics and implications in relation to distributions characteristics and studying the latter s predictability the three peak discharge distributions are estimated for eight drainage basins between 200 and 6000 km2 in northern and western greece they are found to be similar to the ones obtained in the u s a the distributions slopes have no geographic climatic or basin morphological influence and their coefficients of determination are linearly related to the degree of hydrologic non linearity it is shown that only the original peak discharge distribution is necessary and quite sufficient by itself for checking basin hydrologic linearity and accurately predicting peak discharges its slope equal to 1 0 for linear and less than 1 0 for non linear basins is a criterion indicating with its magnitude the degree of basin hydrologic non linearity hydrologic design requires identification of the degree of basin hydrologic non linearity prior to applying linear design methods the latter s application to non linear basins can result in serious design errors the variation in the peak discharge distribution s intercept is significantly explained by the log of any of the two basin morphological indices as l and a l with a the drainage area and l and s the main course length and average bedslope of the river respectively the prediction of the intercept facilitates the distribution estimation in the region

influences of enso on the vertical coupling of atmospheric circulation during the onset of south asian summer monsoon based on multiple sources of atmospheric and oceanic data this study performs a series of composite analysis of the south asian summer monsoon sasm onset against enso events and indicates that warm cold enso events induce later earlier onset of the sasm by modulating the vertical coupling of the upper and lower level circulation over the south asia specifically during the monsoon onset of bay of bengal bob the enso induced convection anomalies over the southern philippines can modulate the position of south asian high sah in late april in the upper troposphere which evolves to affect the monsoon onset convection by changing the upper divergence pumping effect in the lower troposphere enso induces an anomalous zonal gradient of sea surface temperature sst over the indian western pacific ocean to alter the barotropic instability which further affects the formation of bob monsoon onset convection during the indian summer monsoon onset the anomalous convection over northeastern bob and indochina peninsula in late may act to change the sah position and its relevant upper divergence pumping over the arabian sea as meanwhile the indian monsoon onset convection is also modulated by the enso induced changes in intensity of the inertial instability and the forced convection over the as which are related to an enso induced anomalous cross equatorial sst gradient and zonally asymmetric meridional gradient of sea level pressure and an anomalous westerly over the central as in the lower troposphere results demonstrate that during the bob and india monsoon onset the influences of enso on the upper circulation are similar but are distinctly different on the lower level circulation

heating of the tibet plateau and movements of the south asian high during spring abstract the heating of the plateau of tibet the qinghai xizang plateau has been deemed to play an important role in the development and movement of the south asian anticyclone which to a great extent affects the indian monsoon development in this paper the heating effects are estimated from synoptic data from that region for april 1979 during the transition season warming over the plateau interacts with advected synoptic systems and induces the south asian high normally located south of the himalayas during that season to develop strongly and shift northward

strong modulations on the bay of bengal monsoon onset vortex by the first northward propagating intra seasonal oscillation monsoon onset vortex ov in the form of tropical cyclone is often observed in the pre monsoon period and contributes to the subsequent abrupt establishment of summer monsoon over the bay of bengal bob it is identified here that all historical ovs occurred during the convection enhanced phase of the first northward propagating intra seasonal oscillation fniso the individual contributions from the four large scale environmental fields associated with the intra seasonal variations to the cyclone genesis are diagnosed with the aid of the genesis potential index the significant moistening of mid level atmosphere which is embedded in the fniso convection enhanced phase is shown to be the primary factor leading to the cyclone genesis the water vapor budget analysis is further done to understand the governing process for the mid level humidity increase it is clearly seen that the vertical advection process dominated by the anomalous vertical advection of the mean vertical water vapor gradient plays the critical role hence the ovs are shown to be strongly modulated by fnisos both of which are important elements of the complex story of the bob monsoon onset

3 he 4 he ratios in ch 4 rich natural gases suggest magmatic origin natural gas and oil fields commercially exploited since the 1950s are distributed in the zonal area facing the sea of japan in north east japan we report here measurements of the 3he 4he ratios in 27 ch4 rich natural gases obtained from commercial oil and gas wells in the area we observed extraordinarily high 3he 4he ratios up to 8 65 10 6 in gases from wells drilled into deep reservoirs in volcaniclastic rock formations the so called green tuff fig 1 these values are almost identical to those of volcanic fumaroles in the japanese islands in contrast gases in shallower sedimentary rock reservoirs have low 3he 4he ratios with a minimum value of 0 3 10 6 these low values are similar to those of natural gases originating from biological materials this suggests that the formation of natural gas reservoirs in the volcaniclastic rock may be attributed to large scale magmatic activities which occurred in the middle miocene

establishing constraints on groundwater ages with 36cl 14c 3h and noble gases a case study in the eastern paris basin france abstract groundwaters from the tithonian kimmeridgian oxfordian and upper dogger aquifers within the eastern part of the paris basin france were characterised using 3 h 14 c and 36 cl and noble gases tracers to evaluate their residence times and determine their recharge period this information is an important prerequisite to evaluating the confinement properties of the callovo oxfordian clay formation sandwiched between the oxfordian aquifer and the dogger aquifer currently being investigated by the french nuclear waste management agency andra for radioactive waste disposal data presented in this paper are used to test 4 hypotheses 1 the oxfordian limestone is isolated from the overlying tithonian kimmeridgian surface aquifer this first hypothesis is supported by the presence of measurable 3 h activities in groundwaters from the surface aquifer 6 11 tu and by its absence in groundwaters derived from deeper aquifers 2 the callovo oxfordian clay sequence in the vicinity of the url serves as an effective barrier to advective flow and transport between the underlying upper dogger aquifer and the overlying oxfordian limestone aquifer this second hypothesis is supported by relatively low concentrations of cl 3 5 78 mg l 1 na 15 145 mg l 1 br 0 08 0 4 mg l 1 and 4 he rad 0 2 2 3 ccstp g 1 and slightly higher 36 cl cl ratios 2 7 59 10 15 at at 1 in groundwaters from the oxfordian aquifer compared to those from the upper dogger aquifer 345 4027 mgcl l 1 402 2390 mgna l 1 1 8 22 2 mgbr l 1 1 6 37 2 ccstp he g 1 1 5 10 15 at 36 cl at 1 cl 3 groundwaters from the oxfordian aquifer in the vicinity of url are pre holocene with residence times exceeding 10 ka geochemical and isotopic lines of evidence for this hypothesis include a 13 c values measured on oxfordian aquifer waters that are close to 13 c of the aquifer matrix reflecting strong isotopic exchange over several thousand years b noble gas temperatures that indicate recharge temperatures between 3 and 8 6 c lower by 2 7 c than the modern average temperature in this area c radiogenic 4 he concentrations between 0 16 10 5 and 2 3 10 5 ccstp g 1 of water about 2 3 orders of magnitude greater than the 4 he concentration of air equilibrated water 4 groundwater residence time for the upper dogger aquifer in the vicinity of the url probably exceed several hundred thousand years such long residence times are indicated by the accumulation of radiogenic he up to 37 10 5 ccstp g 1 assuming a closed system primary contributors to uncertainties in interpretation of the data presented in this paper are the lack of well defined 36 cl cl input ratio knowledge about the 4 he rad sources for oxfordian and dogger aquifers knowledge about transport processes occurring through the dogger aquifer and the extensive dilution of initial 14 c activities by dissolution exchange with aquifer matrix overall however although the data presented in this paper remain semi quantitative due to inevitable intrinsic limitations of the methods none contradict the hypotheses of long residence times and aquifer isolation in the vicinity of the url

water circulation control on carbonate δ18o records in a low permeability clay formation and surrounding limestones the upper dogger oxfordian sequence from the eastern paris basin france abstract upper dogger to oxfordian formations in the eastern part of the paris basin france are currently being investigated by the french nuclear waste management agency andra testing the feasibility of long term deep nuclear waste disposal in the callovo oxfordian claystones characterising the hydrogeological behaviour of the callovo oxfordian claystones is therefore essential in evaluating its potential as a geological barrier in order to evaluate and quantify water rock interactions experienced over geological time by these formations bulk carbonate 13 c and 18 o were measured and calculations of water rock ratios were used to explain carbonate 18 o changes meteoric porewater and a maximum temperature reached of about 40 c were considered the jurassic marine carbonate 13 c was preserved in the callovo oxfordian claystones and in the overlying limestones 0 28 to 3 39 pdb while the 18 o values are lower by 0 5 6 25 to 1 32 pdb calculations show that upper dogger and oxfordian limestone 18 o data i have random like distribution through theoretical 18 o w r curves and ii suggest that water rock ratios 0 08 0 4 needed to explain 18 o changes are higher by a factor of about 2 20 compared to the present day water rock ratio these features indicate advection in both aquifers according to the history of the paris basin this hydrogeological behaviour could have been effective since jurassic cretaceous transition times inversely the carbonate 18 o content trends observed for the callovo oxfordian data show that changes were controlled by post depositional fluid rock interaction with water rock ratio 0 02 0 15 similar to the present day porewater rock ratio the 130 m thick callovo oxfordian claystone appears remarkably homogenous regarding its hydrogeological properties this study suggests an initial marine porewater replacement by meteoric water only after porosity was reduced to its present value thus demonstrating that the callovo oxfordian clay has mainly been isolated from advective meteoric water circulation only the upper 20 m of the callovo oxfordian claystone formation underwent heterogeneous water rock exchange w r from 0 01 to 0 3 probably as a result of its mineralogical heterogeneity and proximity to the advective oxfordian limestone aquifer this study of carbonate 18 o confirms the hydrogeological barrier properties of the callovo oxfordian clay and suggests that it has been a natural hydrological barrier since the earliest times of its diagenesis

subseasonal intensity variation of the south asian high in relationship to diabatic heating observation and cmip5 models this study investigates the subseasonal intensity variation of south asian high sah and the dynamic linkage with precipitation induced diabatic heating during the summer of 1979 2005 based on the observation and 18 models from the coupled model intercomparison project cmip5 the sah s intensity variation with a period of approximately 10 36 days is identified both in the observation and 18 models by performing an empirical orthogonal function eof analysis on the standardized subseasonal anomalies in geopotential height at 100 hpa over the sah s main body region with the observed strengthening of the sah an enhanced rainfall belt between 70 120 e migrates northward from the equatorial region the northward propagating rainfall belt occupies almost the whole indian subcontinent indochina peninsula and subtropical east asian regions between 20 40 n when the sah reaches the strongest the relative vorticity diagnosis reveals the dynamical linkage between the subseasonal sah s intensity variation and the precipitation anomalies over the asian monsoon region 1 the observed northward propagating rainfall band forms a horizontal gradient of diabatic heating favoring an enhancement of the sah over its southern part 2 when the rainfall band approaches the regions of south and east asia between 20 40 n the increased vertical gradient of diabatic heating in the upper level contributes significantly to the intensification of the sah 3 the horizontal advection process favors the westward expansion of the sah the observation to model comparisons indicate that the model s capacity to reproduce the sah s intensity variation is highly associated with simulations of the anomalous rainfall band and its northward propagation a realistic reproduction of precipitation anomalies is fundamental to simulating the dynamical processes related to diabatic heating and thus the simulation of the sah s subseasonal intensity variation

basin scale thermal and fluid flow histories revealed by carbonate clumped isotopes δ47 middle jurassic carbonates of the paris basin depocentre the reconstruction of past diagenetic conditions in sedimentary basins is often under constrained this results from both the analytical challenge of performing the required analyses on the minute sample amounts available from diagenetic mineral phases and the lack of tracers for some of the diagenetic parameters the carbonate clumped isotopes thermometry 47 opens new perspectives for unravelling the temperatures of diagenetic phases together with the source of their parent fluids two parameters that are otherwise impossible to constrain in the absence of exploitable fluid inclusions here is reported the study of a large number of sedimentary and diagenetic carbonate phases from middle jurassic reservoirs of the paris basin depocentre by combining detailed petrographic observations with a large number of 47 data n 45 on a well documented paragenetic sequence including calcite and dolomite burial cements the data reveal carbonate crystallization at temperatures between 29 c and 98 c from fluids with 18owater values between 7 and 2 in response to the progressive burial and uplift of the paris basin throughout 165 myr of basin evolution coupled to the time temperature evolution previously estimated from thermal maturity modelling these temperatures allow determining the timing of four successive cementation episodes the overall dataset indicates a history of complex water mixing with a significant contribution of hypersaline waters from the triassic aquifers migrated upward along faults during the cretaceous subsidence of the basin subsequent large scale infiltrations of meteoric waters induced a dilution of these pre existing brines in response to the paris basin uplift in the tertiary overall the data presented here allow proposing an integrated approach to characterize the cementation events affecting the studied carbonate reservoir units based on temperature oxygen isotope composition and salinity of the parent fluids as well as on petrographic grounds this article is protected by copyright all rights reserved

genesis of the south asian high and its impact on the asian summer monsoon onset abstractthe formation of the south asian high sah in spring and its impacts on the asian summer monsoon onset are studied using daily 40 yr ecmwf re analysis era 40 data together with a climate mean composite technique and potential vorticity diabatic heating pv q analysis results demonstrate that about 2 weeks before the asian summer monsoon onset a burst of convection over the southern philippines produces a negative vorticity source to its north the sah in the upper troposphere over the south china sea is then generated as an atmospheric response to this negative vorticity forcing with the streamline field manifesting a gill type pattern afterward the persistent rainfall over the northern indochinese peninsula causes the sah to move westward toward the peninsula consequently a trumpet shaped flow field is formed to its southwest resulting in divergence pumping and atmospheric ascent just over the southeastern bay of bengal bob near the surface as a surface anticyclone is formed over t

helium isotope fluxes and groundwater ages in the dogger aquifer paris basin the dogger aquifer of the paris basin has been shown to be first order homogeneous in its helium concentration and its helium isotopic ratio although slight differences are noted in relation to specific chemical water types the helium isotopic composition of the dogger aquifer contains a small component of mantle helium that is associated with a magmatic input although the heat accompanying this magma is small constraints on the age of the overlying albien aquifer are used to calculate the flux of helium out of the dogger this constraint allows a calculation of the residence time of waters in the dogger aquifer of 4 myr 50 which is significantly longer than estimates derived from hydrologic models and hydrologic testing it is possible that the hydrologic ages and the helium ages can be reconciled by a vertically layered dogger aquifer with gradients in he salinity and fluid flow vertical profiles of fluid composition helium concentration and permeability are required in the paris basin to resolve this question

improved extended reconstruction of sst 1854 1997 abstract an improved sst reconstruction for the 1854 1997 period is developed compared to the version 1 analysis in the western tropical pacific the tropical atlantic and indian oceans more variance is resolved in the new analysis this improved analysis also uses sea ice concentrations to improve the high latitude sst analysis and a modified historical bias correction for the 1939 41 period in addition the new analysis includes an improved error estimate analysis uncertainty is largest in the nineteenth century and during the two world wars due to sparse sampling the near global average sst in the new analysis is consistent with the version 1 reconstruction the 95 confidence uncertainty for the near global average is 0 4 c or more in the nineteenth century near 0 2 c for the first half of the twentieth century and 0 1 c or less after 1950

contrasting relationship between tropical western north pacific convection and rainfall over east asia during indian ocean warm and cold summers abstractusing daily data this study compares the subseasonal seesaw relationship between anomalous tropical western north pacific wnp convection and anomalous rainfall over subtropical east asia during boreal summers june august in which the indian ocean io sea surface temperature is either warmer or colder than normal it is found that the precipitation anomalies over central eastern china 25 35 n 110 120 e associated with the anomalous tropical wnp convection activities during the io cold summers are weaker and less evident compared to that in the io warm summers indicating the seesaw relationship in the io cold summers becomes obscure this contrasting seesaw relationship between the io warm and cold summers is attributed to different patterns of anomalous moisture transportation and vertical motion over central eastern china the anomalous circulations associated with the anomalous tropical wnp convection the pacific japan pj pattern during the io warm and cold summers show that rela

changing dynamical control of early asian summer monsoon in the mid 1990s the seasonal evolution of the upper tropospheric south asian high follows and influences underlying summer monsoon advancement a strong connection between the south asian high and westerly perturbation to the north suggests further planetary scale dynamical control of the monsoon in the mid 1990s a clear location shift of the south asian high in may june was noted and was observed in fewer more frequencies of the high centers over the indochina peninsula iranian plateau continental confinement of monsoonal circulation and precipitation was observed during 1995 2010 as opposed to larger scale development in the asia pacific region during 1979 1994 in view of early summer monsoon evolution a westward shifting and faster migration of the south asian high may imply increased control of the midlatitude dynamics by contrast the convection over the tropical western north pacific wnp has an opposite and delayed contribution to monsoon advancement after the mid 1990s than it had been previously the midlatitude jet stream largely weakened over northern africa and the east asia pacific region corresponding to an increase in the upper tropospheric geopotential heights north of the jet stream climate model experiments further reveal that the warming over europe asia and temperature change in the north atlantic can result in the change in midlatitude perturbations and the monsoon evolution in the mid 1990s suggesting large scale and dynamic impact on monsoon climatology

mantle helium in sacramento basin natural gas wells abstract helium isotope ratios in sacramento basin natural gas wells show a strong mantle signal the3he 4he ratios range from 0 11 times the atmospheric ratio 0 11 ra in the rio vista field to 2 75 ra in the moon bend field indicating that 1 to 34 of the helium is mantle derived 3he 4he versus ch4 4he ratios provide evidence of two component mixing between crustal and magmatic end members extrapolation of the linear regression line to ch4 4he 0 gives a hypothetical magmatic end member 3he 4he ratio of 3 84 ra half the typical mantle ratio this indicates that the magmatic end member may actually represent a mixture of mantle and crustal helium gases which deviate from the simple two component mixture can be explained by addition of pure methane radiogenic 4he or a high n2 he component with 3he 4he 0 6 ra to 1 0 ra the ch4 3he ratio of the magmatic end member remains poorly constrained 0 to 3 109 and one cannot rule out the possibility that a significant proportion of the methane in some fields may be of deep earth origin however fields with the highest 3he 4he ratios are associated with buried plio pleistocene intrusives which have up arched sediments to form hydrocarbon traps the methane in these fields may have been produced by rapid thermal alteration of the intruded sediment elsewhere the methane appears either to have migrated from deeply buried sediments in the western basin or to have been produced by local microbial activity

impact of tropical cyclone development on the instability of south asian high and the summer monsoon onset over bay of bengal this paper analyzes the evolution of the south asian high sah during and after the development of tropical cyclone neoguri over the south china sea scs in mid april 2008 the formation of tropical storm nargis over the bay of bengal bob in late april and the asian summer monsoon onset as well as their interrelationships numerical sensitivity experiments are conducted to explore the underlying mechanism responsible for these seasonal transitions in 2008 it is demonstrated that strong latent heating related with tropical cyclone activities over the scs can enhance the development of the sah aloft and generate zonal asymmetric potential vorticity pv forcing with positive vorticity advection to its east and negative advection to its west following the decay of the tropical cyclone this asymmetric forcing leads to instability development of the sah presenting as a slowly westward propagating rossby wave accompanied by a westward shift of the high pv advection a strong upper tropospheric divergence on the southwest of the sah also shifts westward while positive pv eddies are shed from the high pv advection and eventually arrives in the southern bob such synoptic patterns provide favorable pumping conditions for local cyclonic vorticity to develop the latent heating release from the cyclogenesis further intensifies the upper layer divergence and the lower and upper circulations become phase locked leading to the explosive development of the tropical cyclone over the southern bob consequently a tropical storm is generated and the bob summer monsoon commences

air sea interaction and formation of the asian summer monsoon onset vortex over the bay of bengal in spring over the southern bay of bengal bob a vortex commonly develops followed by the asian summer monsoon onset an analysis of relevant data and a case study reveals that the bob monsoon onset vortex is formed as a consequence of air sea interaction over bob which is modulated by tibetan plateau forcing and the land sea thermal contrast over the south asian area during the spring season tibetan plateau forcing in spring generates a prevailing cold northwesterly over india in the lower troposphere strong surface sensible heating is then released forming a prominent surface cyclone with a strong southwesterly along the coastal ocean in northwestern bob this southwesterly induces a local offshore current and upwelling resulting in cold sea surface temperatures ssts the southwesterly together with the near equatorial westerly also results in a surface anticyclone with descending air over most of bob and a cyclone with ascending air over the southern part of bob in the eastern part of central bob where sky is clear surface wind is weak and ocean mixed layer is shallow intense solar radiation and low energy loss due to weak surface latent and sensible heat fluxes act onto a thin ocean layer resulting in the development of a unique bob warm pool in spring near the surface water vapor is transferred from northern bob and other regions to southeastern bob where surface sensible heating is relatively high the atmospheric available potential energy is generated and converted to kinetic energy thereby resulting in vortex formation the vortex then intensifies and moves northward where sst is higher and surface sensible heating is stronger meanwhile the zonal mean kinetic energy is converted to eddy kinetic energy in the area east of the vortex and the vortex turns eastward eventually southwesterly sweeps over eastern bob and merges with the subtropical westerly leading to the onset of the asian summer monsoon