variations of the east asian jet stream and asian pacific american winter climate anomalies in this study the authors apply the ncep ncar reanalysis and other observations to depict the association of the asian pacific american climate with the east asian jet stream eajs with an emphasis on boreal winter seasons and on interannual timescales they analyze the variations of the eajs and their relationships with el nino southern oscillation enso and extratropical north pacific sea surface temperature sst and assess the relative connections of the eajs and enso to the anomalies of atmospheric circulation surface temperature and precipitation in the asian pacific american region it is found that the eajs is coupled to a teleconnection pattern spanning the entire asian pacific american region with the strongest signals over east asia and the western pacific this pattern differs significantly from that associated with enso which influences the earth s climate extensively with a strongest impact on the climate over the central pacific and east a strong eajs is associated with an intensification of the weather and climate systems in asia and over the pacific such as deepening of the east asian trough and the aleutian low and strengthening of the east asian winter monsoon it is linked to colder and drier conditions in east asia and stronger convection over the tropical asia australia sector compared with enso the eajs seems to link to the climate signals of asia and the pacific more strongly an intensified eajs is also associated with anomalies of temperature and precipitation in north america due to the related changes in stationary wave patterns while the eajs does not strongly link to the tropical central eastern pacific sst it is significantly associated with the extratropical north pacific sst more specifically the second most dominant mode of the empirical orthogonal function analysis of the sst in addition a strong weak eajs seems to follow a large small meridional gradient of the western pacific sst associated with warming cooling in the tropics subtropics and cooling warming in the extratropics

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

onset of the summer monsoon over the indochina peninsula climatology and interannual variations abstract the temporal and spatial structures of the atmospheric circulation associated with the climatology and interannual variations of the summer monsoon onset over the indochina peninsula were studied using the observed daily rainfall at 30 stations and the ncep ncar reanalysis from 1951 to 1996 the climatological monsoon onset over indochina is on 9 may with a standard deviation of 12 days the monsoon onset is characterized by the pronounced northeastward progression of the low level southwesterlies over the indian ocean and the intensification and northward extension of the tropical convection from sumatra it coincides with the weakening of the midlatitude westerly over south asia and the westward propagation of the intraseasonal oscillation iso originated in the south china sea scs and the western pacific with a dominant timescale of 12 25 days a close relationship between the interannual variations of the monsoon onset and el nino la nina was identified years with warm cold sea surfac

quaternary glaciation of the himalayan tibetan orogen glacial geological evidence from throughout the himalayan tibetan orogen is examined to determine the timing and extent of late quaternary glaciation in this region and its relation to similar changes on a global scale the evidence summarised here supports the existence of expanded ice caps and extensive valley glacier systems throughout the region during the late quaternary however it cannot yet be determined whether the timing of the extent of maximum glaciation was synchronous throughout the entire region or whether the response was more varied the lack of organic material needed for radiocarbon dating has hindered past progress in glacial reconstruction however application of optically stimulated luminescence and terrestrial cosmogenic radionuclide methods has recently expanded the number of chronologies throughout the region limits to the precision and accuracy available with these methods and more importantly geological uncertainty imposed by processes of moraine formation and alteration both conspire to limit the time resolution on which correlations can be made to milankovitch timescales several ka in order to put all studies on a common scale well dated sites have been re evaluated and all the published terrestrial cosmogenic nuclide ages for moraine boulders and glacially eroded surfaces in the himalayan tibetan orogen have been recalculated locally detailed studies indicate that there are considerable variations in the extent of glaciation from one region to the next during a glaciation glaciers throughout monsoon influenced tibet the himalaya and the transhimalaya are likely synchronous both with climate change resulting from oscillations in the south asian monsoon and with northern hemisphere cooling cycles in contrast glaciers in pamir in the far western regions of the himalayan tibet orogen advanced asynchronously relative to the other regions that are monsoon influenced regions and appear to be mainly in phase with the northern hemisphere cooling cycles broad patterns of local and regional variability based on equilibrium line altitudes have yet to be fully assessed but have the potential to help define changes in climatic gradients over time copyright 2008 john wiley sons ltd

upstream subtropical signals preceding the asian summer monsoon circulation in this study the authors address several issues with respect to the antecedent signals of the large scale asian summer monsoon that were earlier identified by webster and yang in particular they revisit the changes in the subtropical upper tropospheric westerlies preceding the monsoon depict the detailed structure of the monsoon s antecedent signals and investigate the physical processes from the signals to the monsoon they also explore the teleconnection of these signals to various large scale climate phenomena and emphasize the importance of the upstream location of the signals relative to the tibetan plateau and the monsoon before a strong weak asian summer monsoon the 200 mb westerlies over subtropical asia are weak strong during the previous winter and spring a significant feature of these signals is represented by the variability of the middle east jet stream whose changes are linked to the arctic oscillation north atlantic oscillation el

chemostratigraphic age model for the tornillo group a possible link between fluvial stratigraphy and climate abstract the expression of global climate trends 10 6 to 10 7 years and events 10 5 years in terrestrial sedimentary sections can only be assessed from long continuous continental records such records are rare due to the paucity of well dated terrestrial deposits covering millions of years this study uses isotope chemostratigraphy to develop an age model for fluvial sedimentary rocks of the tornillo group tornillo basin tx and to decipher the potential expression of global climate variations in this sub tropical paleo fluvial system the carbon isotope ratio 13 c of tornillo group pedogenic carbonate correlates well with 13 c variations from benthic foraminifera and suggests deposition between 69 ma and 52 ma for the studied stratigraphic interval higher sediment accumulation rates occurred in the greenhouse period of the early eocene than during the cooler middle paleocene carbon isotope excursions associated with eocene hyperthermals were not identified but their predicted stratigraphic positions coincide with thick sand bodies we interpret the long term sediment accumulation rates and rapid shifts in facies distribution as reflecting change in sediment supply in the basin possibly driven by fluctuations in precipitation seasonality and intensity driven associated with global temperature changes carbon and oxygen isotope ratios from pedogenic carbonates display a strong correlation throughout the section interpreted as an expression of coupling between the hydrological cycle and soil processes those observations suggest that global climate variations along with tectonic and eustatic sea level changes may be an important control of stratigraphic variations of the tornillo group at multiple timescales

a solar irradiance trigger for millennial scale abrupt changes in the southwest monsoon 1 marine sedimentary records of the last glacial from tropical monsoon latitudes indicate climate fluctuations comparable to rapid changes in 18o recorded in greenland synchronizing two high resolution sedimentary records from the oman and pakistan margins we resolve millennial scale reversals in sea surface temperature sst gradient sst across the arabian sea which directly correspond with the majority of dansgaard oeschger d o events for the last 65 kyr the relative amplitude of individual monsoon and d o events appears comparable suggesting coupled and at least hemispheric forcing to explore this quasi cyclic forcing we compare alkenone based geologic data with modern satellite derived sst estimates between sites interstadial conditions fall within the range of monsoons during the holocene but stadial conditions have no analogs following published associations between eurasian winter snow cover ewsc and monsoon rainfall and el nino southern oscillation enso events and anomalous ewsc we find a good correlation between the southern oscillation index soi and arabian sea sst throughout the modern data set an apparent 11 year cyclicity in the soi reveals an association between the monsoon soi and solar output variability the soi primarily tracks solar total irradiance but the soi monsoon linkage becomes nonlinear during excursions of the soi associated with el nino events strong el ninos coincide precisely with minimum solar irradiance during the solar cycle which we attribute to threshold behavior in tropical pacific ssts and associated trade wind strength we propose that both short term interannual decadal and long term centennial millennial changes in solar output are consistent with records of enso variability monsoon intensity and d o event timing

organic control on shoreface stacking patterns bogged down in the mire in ever wet climates raised mires that are elevated several metres above flood levels can cover significant portions of coastal plains because peat accumulation may keep pace with moderate rates of base level rise the development of raised mires may reduced the areal extent of marine transgressions thick low ash coals are present immediately landward of many vertically stacked shoreface parasequences in cretaceous state of the western interior of north america we suggest that these coals formed in raised mires that stabilized shorelines for long periods of time in such settings the rate of sediment supply including peat accumulation to the coastal environment is partly a function of the rate of change in base level

sensitivity of the asian summer monsoon to aspects of sea surface temperature anomalies in the tropical pacific ocean summary the response of both the time of onset and the strength of the asian summer monsoon to regional aspects of the sea surface temperature sst anomalies in the tropical pacific ocean associated with el nifio southern oscillation enso has been investigated through a series of sensitivity experiments with the universities global atmospheric modelling programme ugamp general circulation model ugcm this paper builds on the work of ju and slingo 1995 and on their hypothesis that the relationship between the asian summer monsoon and enso involved the latitudinal position and strength of the tropical convective maximum tcm over indonesia and the west pacific in the preceding spring the inference from their results was that the modulation of the tcm might be associated either with changes in the walker circulation through the influence of the east pacific sst anomalies or with changes in the local hadley circulation associated with the in situ sst anomalies in the west pacific the investigation has focused on the particular contrasting years of 1983 and 1984 the experiments described in this paper are designed to isolate the effects of the principal sst anomalies in the east and central pacific associated with el niiio la nifia from those of opposite sign which develop in the west pacific as a complementary pattern during the mature phase of el nifiola niba the results of the experimentation suggest that at least for the test cases of 1983 and 1984 the modulation of the walker circulation with implied additional subsidence over the eastern hemisphere is the dominant mechanism whereby the asian summer monsoon is weakened during el nifio years however the late onset during el nifio years may also be associated with the complementary cold sst anomalies in the west pacific which delay the northwards transition of the tcm during la nifia the modulation of the walker circulation appears not to be the controlling factor which determines the stronger monsoons the ugcm results suggest that the complementary warm sst anomalies in the west pacific enhance the tcm and it is this in situ response by the tcm that leads to an early onset and stronger monsoon the importance of warm anomalies in the west pacific in the development of a strong monsoon has been investigated further through a case study of the 1994 season the year 1994 was an el nifio year in which the monsoon was unexpectedly active but which was also marked by wanner than normal ssts in the west pacific the sensitivity experiments have also elucidated the role of el nibo in influencing the precursory signature of stronger subtropical westerlies over india and south east asia during the winter and spring preceding weak monsoons the results suggested that the equatorwards shift of the subtropical jet is a remote response to the warm sst anomalies in the central and east pacific associated with el nifio

timing and style of late quaternary glaciation in northeastern tibet glacial successions in the anyemaqen and nianbaoyeze mountains of northeastern tibet are reassessed and new glacial chronologies are presented for these regions cosmogenic radionuclide and optically stimulated luminescence dating indicates that two glacial advances occurred in marine isotope stage mis 3 and mis 2 in the anyemaqen mountains a third advance occurred in the early holocene we suggest that glaciation was synchronous in the anyemaqen and nianbaoyeze mountains as well as in other glaciated areas of tibet and the himalaya that are influenced by the asian monsoon the maximum extent of glaciation occurred early in the last glacial cycle mis 3 during a time of increased insolation when the monsoon intensified and supplied abundant precipitation as snow at high altitude to feed high altitude glaciers this suggests that precipitation as snow is fundamental in controlling glaciation in these regions however the occurrence of glacial advances during the insolation minimum of mis 2 suggests that despite reduced precipitation at this time the annual temperatures were cold enough to maintain positive glacier mass balances the numerically defined chronologies for the anyemaqen and nianbaoyeze mountains presented here provide a framework for comparing glacial advances in other parts of high asia

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

ensemble simulations of asian australian monsoon variability by 11 agcms ensemble simulations of asian australian monsoon a am anomalies were evaluated in 11 atmospheric general circulation models for the unprecedented el nino period of september 1996 august 1998 the models simulations of anomalous asian summer rainfall patterns in the a am region 308s 308n 408 1608e are considerably poorer than in the el nino region this is mainly due to a lack of skill over southeast asia and the western north pacific 58 308n 808 1508e which is a striking characteristic of all the models the models deficiencies result from failing to simulate correctly the relationship between the local summer rainfall and the sst anomalies over the philippine sea the south china sea and the bay of bengal the observed rainfall anomalies are negatively correlated with sst anomalies whereas in nearly all models the rainfall anomalies are positively correlated with sst anomalies while the models physical parameterizations have large uncer tainties this problem is primarily attributed to the experimental design in which the atmosphere is forced to respond passively to the specified ssts while in nature the ssts result in part from the atmospheric forcing regional monsoon dynamic indices are calculated for the indian the western north pacific and the australian monsoons respectively most models can realistically reproduce the western north pacific and australian mon soon yet fail with the indian monsoon to see whether this is generally the case a suite of five seoul national university model runs with the same observed lower boundary forcing and differing only in their initial conditions was examined for the period 1950 98 the skill in the 49 yr ensemble simulations of the indian monsoon is significantly higher than the skill for the period 1996 98 in other words for the unprecedented 1997 98 el nino period the models under study experience unusual difficulties in simulating the indian monsoon circulation anomalies moreover the observed webster yang index shows a decreasing trend over the last 50 yr a trend missed by the models ensemble simulations

moist dynamics of severe monsoons over south asia role of the tropical sst abstractdiagnostics from observations and multicentury integrations of a coupled model geophysical fluid dynamics laboratory gfdl coupled model version 2 1 cm2 1 indicate that about 65 of the severe monsoons rainfall 1 5 standard deviations of its long term mean over south asia are associated with sea surface temperature sst anomalies over the equatorial pacific during the developing phase of enso and another 30 are associated with sst variations over the tropical indo pacific warm pool the present research aims to identify the moist processes that initiate the dryness wetness and provide a precursor for rainfall anomalies over south asia in spring during el nino la nina the hypothesis in this paper based on cm2 1 composites is that at low levels el nino forced equatorial easterly wind anomalies over the indian ocean resulting from ekman pumping promote anticyclonic vorticity over the northern indian ocean whose poleward flank advects dry air from northern latitudes to south asia

high resolution linkage of channel coastal plain and shallow marine facies belts desert member to lower castlegate sandstone stratigraphic interval book cliffs utah colorado usa

space time evolution of meteorological features associated with the onset of indian summer monsoon abstract to study the climatological structure of the atmospheric fields during the onset phase of the indian summer monsoon a composite analysis of different meteorological parameters over indian stations is carried out the composites are constructed relative to a uniform set of onset dates over south kerala over the peninsular indian stations the rainfall composites show sudden and sharp increases with onset except in the case of east coast stations where rainfall does not substantially change with the onset of the summer monsoon the composite wind analysis demonstrates how the upper tropospheric subtropical westerlies weaken and shift poleward and the tropical easterlies strengthen and spread north with the onset of the monsoon the onset vortex that takes the monsoon northward along the west coast in many years is clearly discernible between 600 and 400 hpa in the composite streamline charts the relative humidity builds up suddenly in the vertical a few days before the onset at the respective s

role of high and low frequency winds and wave reflection in the onset growth and termination of the 1997 1998 el nino the present study aims at studying the role played by high frequency wind variability wave reflection and easterly wind anomalies in the western pacific in the onset growth and termination phases of the 1997 1998 el nino using the trident intermediate coupled model and observations while the anomalous strength of the trade winds in 1996 favored the initiation of a warm event in 1997 via western pacific boundary rossby wave reflection the actual timing of the onset and the amplitude of the event resulted from the large march 1997 wind event once initiated high frequency westerly winds strongly contributed to the rapid growth of the warm event and to the displacement of the eastern edge of the warm pool moreover both easterly and westerly high frequency wind variability in 1997 1998 contributed to the amplitude of the event set the evolution of the warm event and potentially influenced the equatorial pacific conditions at least one year after the el nino event in addition eastern boundary reflection also significantly contributed to the amplitude and duration of the warm event whereas its termination was a combination of various factors reflection of upwelling rossby waves at the western boundary and large easterly wind anomalies observed in the western pacific from november 1997 to early 1998 these factors were sufficient to terminate the event and to switch temperature anomalies from warm to cold to conclude understanding the coupling between the high and low frequency wind variability i e studying enso as a multi scale phenomenon will certainly lead to a better comprehension of the diversity of its behavior and potentially to an improvement of its predictability

dynamics of the indian monsoon and enso relationships in the sintex global coupled model this paper uses recent gridded climatological data and a coupled general circulation model gcm simulation in order to assess the relationships between the interannual variability of the indian summer monsoon ism and the el nino southern oscillation enso the focus is on the dynamics of the ism enso relationships and the ability of the state of the art coupled gcm to reproduce the complex lead lag relationships between the ism and the enso the coupled gcm is successful in reproducing the ism circulation and rainfall climatology in the indian areas even though the entire ism circulation is weaker relative to that observed in both observations and in the simulation the ism rainfall anomalies are significantly associated with fluctuations of the hadley circulation and the 200 hpa zonal wind anomalies over the indian ocean a quasi biennial time scale is found to structure the ism dynamical and rainfall indices in both cases moreover ism indices have a similar interannual variability in the simulation and observations the coupled model is less successful in simulating the annual cycle in the tropical pacific a major model bias is the eastward displacement of the western north pacific inter tropical convergence zone itcz near the dateline during northern summer this introduces a strong semiannual component in pacific walker circulation indices and central equatorial pacific sea surface temperatures another weakness of the coupled model is a less than adequate simulation of the southern oscillation due to an erroneous eastward extension of the southern pacific convergence zone spcz year round despite these problems the coupled model captures some aspects of the interannual variability in the tropical pacific enso events are phase locked with the annual cycle as observed but are of reduced amplitude relative to the observations wavelet analysis of the model nino34 time series shows enhanced power in the 2 4 year band as compared to the 2 8 year range for observations during the 1950 2000 period the ism circulation is weakened during enso years in both the simulation and the observations however the model fails to reproduce the lead lag relationship between the ism and nino34 sea surface temperatures ssts furthermore lag correlations show that the delayed response of the wind stress over the central pacific to ism variability is insignificant in the simulation these features are mainly due to the unrealistic interannual variability simulated by the model in the western north pacific the amplitude and even the sign of the simulated surface and upper level wind anomalies in these areas are not consistent with observed patterns during weak strong ism years the ism and western north pacific itcz fluctuate independently in the observations while they are negatively and significantly correlated in the simulation this isolates the pacific walker circulation from the ism forcing these systematic errors may also contribute to the reduced amplitude of enso variability in the coupled simulation most of the unrealistic features in simulating the indo pacific interannual variability may be traced back to systematic errors in the base state of the coupled model

climatic and topographic controls on the style and timing of late quaternary glaciation throughout tibet and the himalaya defined by 10be cosmogenic radionuclide surface exposure dating abstract temporal and spatial changes in glacier cover throughout the late quaternary in tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region and the lack of numerical dating to help reconstruct the timing and extent of glaciation throughout tibet and the bordering mountains we use geomorphic mapping and 10 be cosmogenic radionuclide crn surface dating in study areas in southeastern gonga shan southern karola pass and central western nyainqentanggulha shan and tanggula shan tibet and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands each of the study regions receives its precipitation mainly during the south asian summer monsoon when it falls as snow at high altitudes gonga shan receives the most precipitation 2000 mm a 1 while near the margins of monsoon influence the karola pass receives moderate amounts of precipitation 500 600 mm a 1 and in the interior of the plateau little precipitation falls on the western nyainqentanggulha shan 300 mm a 1 and the tanggula shan 400 700 mm a 1 the higher precipitation values for the tanggula shan are due to strong orographic effects in each region at least three sets of moraines and associated landforms are preserved providing evidence for multiple glaciations the 10 be crn surface exposure dating shows that the formation of moraines in gonga shan occurred during the early mid holocene neoglacial and little ice age on the karola pass during the lateglacial early holocene and neoglacial in the nyainqentanggulha shan date during the early part of the last glacial cycle global last glacial maximum and lateglacial and on the tanggula shan during the penultimate glacial cycle and the early part of the last glacial cycle the oldest moraine succession in each of these regions varies from the early holocene gonga shan lateglacial karola pass early last glacial western nyainqentanggulha shan and penultimate glacial cycle tanggula shan we believe that the regional patterns and timing of glaciation reflect temporal and spatial variability in the south asian monsoon and in particular in regional precipitation gradients in zones of greater aridity the extent of glaciation has become increasingly restricted throughout the late quaternary leading to the preservation of old 100 ka glacial landforms in contrast in regions that are very strongly influenced by the monsoon 1600 mm a 1 the preservation potential of pre lateglacial moraine successions is generally extremely poor this is possibly because lateglacial and holocene glacial advances may have been more extensive than early glaciations and hence may have destroyed any landform or sedimentary evidence of earlier glaciations furthermore the intense denudation mainly by fluvial and mass movement processes which characterize these wetter environments results in rapid erosion and re sedimentation of glacial and associated landforms which also contributes to their poor preservation potential

reservoir analog studies using multimodel photogrammetry a new tool for the petroleum industry an advanced photogrammetric method called multimodel stereo restitution is a potential new tool for the petroleum industry when outcrop investigations are necessary such as in reservoir analog studies the method is based on very simple field photography techniques allowing the geologist to use his own standard small frame camera e g 24 36 or 60 60 mm formats it can be applied to geological studies of virtually any scale and outcrop mapping is significantly improved in detail accuracy and volume the method is especially useful when investigating poorly accessible exposures on steep mountain faces and canyon walls the use of multimodel photogrammetry is illustrated by a study of upper cretaceous deltaic sediments from the atane formation of west greenland detailed vertical cross sections of all outcrops in the area are measured and in addition horizontal maps of individual sand bodies are compiled on this basis data such as width thickness ratios sinuosity and the shapes of sand bodies and paleochannels crucial in reservoir analog studies are quantified and collected further potential applications of the method in petroleum explorations are discussed true scale mapping of lithologies in large continuous exposures can be used in understanding basin evolution and in seismic modeling close range applications can be used when modeling fault geometries and in studies of individual bed forms clay laminae cemented horizons and diagenetic fronts

interannual variability of summer monsoon onset over the western north pacific and the underlying processes climatological summer monsoon onset over the south china sea scs and the western north pacific wnp defined as the region of 108 208n 1208 1608e displays three distinct stages around mid may monsoon rain commences in the scs and the philippines in early to mid june the monsoon rain extends to the southwestern philippine sea after mid july the rainy season starts in the northeastern part of the wnp the onset anomaly however displays an in phase interannual variation across the entire wnp domain the standard deviation of the onset date increases eastward from 3 pentads in the scs to 5 pentads in the northeastern part of the domain the large onset variability in the wnp is mainly attributed to large year to year changes of the seasonal cycle

micromorphology and sequence stratigraphy of the interfluve paleosols from the ganga plains a record of alluvial cyclicity and paleoclimate during the late quaternary

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

alleviation of a systematic westerly bias in general circulation and numerical weather prediction models through an orographic gravity wave drag parametrization systematic westerly biases in the northern hemisphere wintertime flow of the meteorological office 15 layer operational model and 11 layer general circulation model are described evidence that the failure to parametrize subgrid scale orographic gravity wave drag may account for such biases is presented this evidence is taken from aircraft studies surface pressure drag measurements and studies of the zonally averaged momentum budget a parametrization scheme is described in which the surface stress is proportional to the near surface wind speed and static stability and to the variance of subgrid scale orography the stress is absorbed in the vertical by considering the influence of such gravity wave activity on static stability and vertical wind shear a richardson number dependent wave breaking formulation is devised and the vertical stress profile determined by a saturation hypothesis whereby the breaking waves are maintained at marginal stability it is shown that wave breaking preferentially occurs in the boundary layer and in the lower stratosphere results from a simple zonally symmetric model show how the adjustment to thermal wind balance with a wave drag in the stratosphere warms polar regions by adiabatic descent and decelerates the mean westerlies in the troposphere the influence of the parametrization scheme on integrations of the 11 layer model is described and found to be generally beneficial in a discussion of the reasons why this problem has only recently emerged it is suggested that the satisfactory northern hemisphere winter circulations of previous coarser general circulation models were due to a compensation implied by underestimating both the surface drag and the horizontal flux of momentum by explicitly resolved large scale eddies

western pacific ocean influences on monsoon precipitation in the southwestern chinese loess plateau since the mid holocene numerous paleoclimate records on reconstructed monsoon precipitation isotopes dp and 18op have been published to infer past hydroclimate changes in asian monsoon region however there are still debates on whether or not these reconstructed dp or 18op can represent changes of monsoon precipitation in this study we report a 5000 year record of leafwax hydrogen isotope dwax from a 6 67 m long sediment core collected in beilianchi blc lake in the southwestern chinese loess plateau based on analyses of the instrumental precipitation isotopes precipitation amounts and moisture sources we find that dp in the southwestern chinese loess plateau shows distinct negative correlation with amounts of summer from april to september monsoon precipitation at inter annual scales this is further supported by the observed negative relation between precipitation amounts and regional lake sediments and speleothems inferred dp or 18op values at decadal scales over the past 60 years therefore our reconstructed 35 year resolution monsoon precipitation inferred from dwax reveals a long term decrease since the mid holocene superimposed on this trend there are several multi centennial to millennial scale fluctuations for increased monsoon precipitation at 4500 4000 years bp 2900 2400 years bp and 1200 700 years bp and decreased precipitation at 3900 3000 years bp 2200 1300 years bp and 500 0 years bp reanalyses of instrumental data and kiel climate model on regional atmosphere circulations show that moisture of this region is mainly derived from the western pacific ocean through the east asian summer monsoon circulation at inter annual to inter decadal and millennial timescales we conclude that monsoon rainfall in the southwestern chinese loess plateau is likely connected with changes in sea surface temperatures and migrations of the itcz in the western pacific ocean

sequential architecture in a fluvial succession sequence stratigraphy in the upper cretaceous mesaverde group prince canyon utah abstract five unconformity bounded sequences have been documented within a 1300 m thick succession of predominantly fluvial upper cretaceous and lower tertiary deposits in the price canyon area of the westernmost part of the book cliffs east central utah u s a this area experienced major tectonically induced changes in the paleogeography during deposition the earliest fluvial deposits in the study area were formed in a relatively simple foreland basin setting in front of the sevier orogenic belt and contain more marine influence than previously recorded following a gradual termination of thrusting sedimentation became increasingly controlled by uplift of the san rafael swell to the southeast our studies suggest that the fluvial systems in the upper part of the succession alternated bet een being confined within a valley open towards the north and being more directly eastward flowing on the basis of the observed sequences an idealized model of alluvial sequences whose internal architecture can be related to a fall rise fall cycle of the stratigraphic base level has been established upward or downward changes in the position of this base level dictate the creation and destruction of accommodation on the alluvial plain and therefore exert a direct control on the sequential architecture and sandstone body geometry of fluvial successions in our model the basal sequence boundary is overlain by an amalgamated fluvial sandstone sheet the sheet is succeeded by a fining upward more mudstone rich level with more isolated sandstone bodies and this level may culminate in a marine or lacustrine transgression the upper part of the sequence may show a coarsening upward trend heralding the next phase of base level fall and sequence boundary generation use of the suggested model has the potential to refine existing lithostratigraphic schemes and given the higher resolution and more detailed correlation may significantly improve paleogeographic reconstructions and aid in prediction of potentially hydrocarbon bearing reservoirs a revised and refined lithostratigraphy has been established on the basis of alluvial sequence analysis the lower half of the succession forms the youngest part of a major eastward prograding clastic tongue the mesaverde group and is campanian we divide this part into the blackhawk castlegate and price river formations the rest of the succession is maastrichtian to paleocene and is referred to the north horn formation this formation was deposited in an intermontane setting

on the role of sea surface temperature gradients in forcing low level winds and convergence in the tropics abstract we examine the importance of pressure gradients due to surface temperature gradients to low level p 700 mb flow and convergence in the tropics over time scales 1 month the latter plays a crucial role in determining the distribution of cumulonimbus convection and rainfall our approach is to consider a simple one layer model of the trade cumulus boundary layer wherein surface temperature gradients are mixed vertically consistent with ecmwf analyzed data the top of the layer is taken at 700 mb the influence from higher levels is intentionally suppressed by setting horizontal pressure gradients and frictional stresses to zero at the top of the layer horizontal convergence within the layer is taken up by cumulonimbus mass flux however the development of the cumulonimbus mass flux is associated with a short relaxation time o hr roughly the development time for such convection during this short time horizontal convergence acts to redistribute mass so as to reduce horizontal pressur

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

impacts of small scale faults on continental to coastal plain deposition evidence from the realgrunnen subgroup in the goliat field southwest barents sea norway abstract in this study we synthesise sedimentological fault and amplitude versus angle ava analysis and propose that the fruholmen and tubaen formations realgrunnen subgroup are syn kinematic deposits that record a previously undocumented early phase of mesozoic rifting on the troms finnmark fault complex and within the hammerfest basin the realgrunnen subgroup hosts one of two triassic reservoirs currently being produced in the goliat field here the subgroup sits unconformably on top of the storfjorden subgroup carnian snadd formation away from the goliat field which is characterised by a periclinal anticline the realgrunnen subgroup also comprises the lower middle jurassic nordmela and sto formations sedimentological analysis of six exploration wells reveals that the fruholmen formation was deposited in a prodelta to delta plain environment where tide influenced and fluvial dominated distributary channels are represented by clay siltstones and very fine grained sandstones the overlying tubaen formation is characterised by medium to very coarse grained deposits locally conglomeratic and represents a widespread braid plain with localised alluvial fans displacement profiles of faults and along fault thickness variations demonstrate that an immature fault system was active during deposition of the realgrunnen subgroup a series of unconnected fault segments hosted isolated sub basins and erosional catchment areas in their hanging and footwalls respectively an ava attribute map generated from a 10 ms interval of the uppermost part of the subgroup reveals gross sand prone depositional bodies i e individual and amalgamated channels some of which show meandering geometries ox bow lakes and alluvial fans sand bodies frequently show elongate geometries parallel to faults indicative of syn depositional fault related subsidence driving mechanisms responsible for the norian to rhaetian event may relate to contemporaneous rejuvenation of the fennoscandian hinterland development of the novaya zemlya fold and thrust belt and or the early cimmerian tectonic phase in northern europe

thrust loads and foreland basin evolution cretaceous western united states two dimensional modeling of loading during the formation of the idaho wyoming thrust belt shows that regional isostatic compensation by flexure of an elastic lithosphere is sufficient to control the formation of a foreland basin the flexural rigidity of the lithosphere is inferred to have been approximately 1023 nm 1030 dyne cm on the basis of palinspastic comparison of predicted downwarping due to the thrust plate loads to the shape of the sedimentary wedge on the west side of the cretaceous western interior seaway erosion of part of the uplifted thrust plates redistributed the load depositing it farther to the east thereby causing subsidence over a much wider area than could have been accomplished only by the loading by thrust plates paleotopography after major cretaceous thrust events was calculated the resulting mountainous terrain gentle alluvial plain and flat sea floor correspond well with the topography of the modern foreland thrust belt and basin system in the andes of south america and to paleogeographic reconstructions in the western united states thrust belt topography is controlled by the subsurface geometry of the thrust faults particularly the positions of ramp zones and by isostatic subsidence

the dynamics of double monsoon onsets abstract double monsoon onset develops when the strong convection in the bay of bengal is accompanied by the monsoonlike circulation and appears in the indian ocean in early may which is about 3 weeks earlier than the climatological date of the onset 1 jun the initial bogus onset is followed by the flow weakening or reversal and clear sky and dry conditions over the monsoon region the best example of such a phenomenon is the development of the summer monsoon in 1995 when monsoonlike perturbations that appeared in mid may disappeared by the end of the month and were followed by a heat wave in india delaying onset of the monsoon the climatology of double onsets is analyzed and it is shown that they are associated with delay of the monsoon rainfall over india this analysis indicates that the development of bogus onsets depends on the timing of intraseasonal oscillation in the indian ocean and the propagation of convective episodes into the western pacific there is evidence that an sst evolution

onshore to offshore anatomy of a late quaternary source to sink system po plain adriatic sea italy abstract in understanding the evolution of siliciclastic systems late quaternary analogs may enable reliable predictive models of facies tract architecture the po plain adriatic sea system where a wealth of research has been conducted during the last 20 years represents one of the most intensively investigated late quaternary successions with the aid of a chronologically well constrained stratigraphy paleoenvironmental evolution is tracked for the first time from fluvial to deep marine realms over 1000 km in length vertical stacking trends onshore and stratal terminations offshore are the key observations that allow identification of surfaces with sequence stratigraphic significance systems tract boundaries in the distinct segments of the system recurring motifs in stratigraphic architecture showing tight coupling of sedimentary responses among source area catchment basin and coastal and marine depocenters reveal a cyclicity driven by glacio eustatic fluctuations in the milankovitch band due to high rates of subsidence middle pleistocene forced regressive systems tracts are exceptionally expanded and the mis5e mis2 interval late pleistocene preserves a nearly continuous record of fourth order 100 kyr stepwise sea level fall the stratigraphic architecture of last glacial maximum deposits highlights the genetic relations between channel belt development pedogenesis and sediment delivery to the lowstand delta through narrow incised valley conduits the late glacial holocene succession records the last episode of sea level rise and stabilization through well developed patterns of shoreline transgression regression tst hst that can be readily traced updip from offshore to onshore locations architectural styles across the whole system reflect a dominance of allogenic forcing in the tst as opposed to a predominantly autogenic control on stratigraphic development in the hst external drivers of facies architecture were also effective on millennial timescales the younger dryas cold reversal which marks the transgressive surface on land records a short lived episode of subaqueous progradation that is correlative onshore with widespread immature paleosol development and small sized channel belt formation quantitative assessment of sediment budgets over different time intervals requires precise positioning of the key bounding surfaces based on this approach we outline for the first time over the entire po adriatic basin an estimate of the sediment volumes stored in each systems tract

multi scale stratigraphic forward modelling of the surat basin for geological storage of co2 underground geological storage of co2 gsc requires a high level of subsurface understanding that is often hindered by a lack of data this study demonstrates the use of stratigraphic forward modelling sfm in generating and characterising a static reservoir model using limited well data with multiple potential applications within the gsc workflow sedsim sfm software was used to create a static model of the surat basin including a high resolution nested model of the epq 7 gsc tenement within the basin deposition and burial of the jurassic precipice sandstone evergreen formation and hutton sandstone were simulated modelling results show a close match with gamma ray well logs in the tenement area and the model can be considered a credible model of the subsurface the sedsim predicted formation thicknesses and porosity and permeability distributions meet criteria set for gsc suggesting that the epq 7 tenement may be a prospective gsc location

mechanisms of monsoon southern oscillation coupling insights from gcm experiments the relative roles of internal atmospheric dynamics land surface evaporation and sea surface temperature sst forcings on the coupling between the asian monsoon am and the southern oscillation so are investigated in a series of gcm experiments results confirm previous studies indicating that the characteristic large scale pattern of the so is due primarily to sst anomaly ssta forcing the am circulation anomalies are coupled to the so via a characteristic upper level circulation couplet over the equatorial central pacific this couplet acts as a radiating node for teleconnection signals originating from the am region to the extratropics generally a weak am is associated with warm sst over the eastern equatorial pacific concomitant with the negative phase of the so i e low high surface pressure over tahiti darwin the reverse holds for strong am two wavetrains associated with the am fluctuation have been identified one arcing over northeastern asia via the aleutians to north american and another emanating from northwestern europe via siberia to northern india internal dynamics appear to underpin the origin of these wavetrains which are strongly tempered by ssta forcing and to a lesser degree by interactive land processes regionally land atmosphere interaction seems to have the strongest impact over east asia indochina and the adjacent oceanic region of the south china sea here land atmosphere interaction is responsible for the enhancement of a subseasonal scale see saw oscillation in precipitation between land and the adjacent oceans a local land atmosphere feedback mechanism involving strong coupling between the hydrologic and energy cycles is identified it is suggested that the interaction among precipitation moisture convergence and land surface turbulent heat fluxes and radiation processes play key roles in determining the fast subseasonal and shorter scales response of the am on these time scales the occurrences of cool wet and hot dry states associated with the precipitation seesaw appear to be chaotic however the preferred occurrence of a given state and the abrupt transition between states are dependent on the large scale circulation and radiation forcings induced by the so one of the more provocative findings here is that effects of land atmosphere interaction do not seem to alter the basic planetary scale features of the am so system as a result the interannual variability of the coupled am so is relatively small in the absence of anomalous sst forcing yet the local effect of land atmosphere interaction on am is quite pronounced and dependent upon the large scale forcings related to so

basin orogen patterns and the late triassic foreland basin conversion process in the western yangtze block china abstract due to the formation of the qinling and sanjiang orogenic belts along the northern and southwestern margins the western yangtze block experienced a complex basin orogen tectonic transformation forming a unique pattern for a basin orogen system in the late triassic that should be recorded by sediments in the sichuan basin this paper combines with regional tectonics field observations and borehole and seismic exploration data to establish the prototypes of the basins and tectonic frameworks of basin orogen from member 1 m1 to 6 m6 of the xujiahe formation during the late triassic in the western yangtze block from stage m1 to m2 a set of deltaic deposits formed and extended parallel to the qinling orogenic belt indicating that the start of the scissor type collision in the northern margin of the western yangtze block led to the development of the northern sichuan basin and songpan ganzi peripheral foreland basin meanwhile a set of deltaic deposits which occur in the southeastern sichuan basin were controlled by the uplift of the jiangnan xuefeng tectonic belt transforming into a denuded zone at that time a set of deltaic deposits developed in the southwestern part of the western yangtze block indicating the beginning of the initial stage of the related foreland basin in this area at stage m2 from stage m3 the intensive activity of orogenic belts surrounding the western yangtze block shaped the tectono sedimentary features along the margin of the western yangtze block the successive development of delta plain and alluvial fan deposits and their westward and eastward expansions respectively in the north and southwest margins of the western yangtze block reflect the uplift of the qinling and sanjiang orogenic belts while the formation of a set of deltaic deposits in the southeastern part of the western yangtze block results from the persistent uplift of the jiangnan xuefeng tectonic belt during stages m5 to m6 the lacustrine swamp deposits began expansion and became the main sedimentary facies in the western yangtze block southward and northward migrations of the aforementioned two separated foreland basins respectively controlled by qinling and sanjiang orogenic belts caused these two separated foreland basins to connect with each other and to form a single unified complex foreland basin that was controlled by these two orogenic belts these results suggest a two stage foreland basin evolution mode for the western yangtze block during the late triassic at stage i m1 to m4 two separated foreland basins developed in the northern and southwestern margins of the western yangtze block controlled respectively by the qinling and sanjiang orogenic belts during stage ii m5 to m6 these two separated foreland basins connected with each other to form a single composite foreland basin related to those two orogenic belts

style and timing of frontal structures thrust belt central utah the cordilleran fold and thrust belt in central utah may be divided into a western belt of precambrian to lower mesozoic strata shortened above ramp style thrust faults and an eastern belt of folded middle to upper mesozoic rocks shortening in the eastern foldbelt occurred above a bedding plane thrust fault system that terminates within a thick section of jurassic shale siltstone and anhydrite this thrust fault system probably failed to reach the synorogenic erosion surface deformation associated with the thrust system takes the form of ramp anticlines in the west and a regionally extensive triangle zone at the eastern extent of the shortening the ramp structures indicate that the thrust system rose from deeper structural levels and became bedding parallel within th jurassic section the middle jurassic section was approximately doubled in thickness by duplexing within the triangle zone shortening across the triangle zone is approximately 50 5 km or 3 mi demonstrable synthrusting deposits within the region are late early to late cretaceous in age late albian to late campanian the synorogenic rocks were folded above the triangle zone and are now overlain unconformably by strata of tertiary age tertiary clastics onlap structures in the foldbelt and were not deformed by the deformation within the triangle zone the age of synorogenic deposits and structural relations of postorogenic strata indicate that deformation was complete by the close of the cretaceous or early paleocene and support a thrust mechanism for much of the folding in the region

tropical wide teleconnection and oscillation ii the enso monsoon system two teleconnection indices discussed in part i i e the tropical wide oscillation index toi and the walker circulation index wai are applied to the analysis of the enso monsoon el nino southern oscillation asian monsoons system the first hypothesis presented in part i was that the toi for july august september jas is closely related to the indian summer monsoon index as well as the southern oscillation index as a result the toi represents the lead lag characteristics of the tropical circulation variability over the eastern hemisphere 45 e 170 e and simultaneously its interaction with the enso over the equatorial pacific the second hypothesis was that there are two types of connection between the enso and asian monsoons type i with distinct connection in space and time and type ii without connection the wai provides a measure for this connection this idea is supported by comparisons of observed and model teleconnection structures in part i part ii investigates these relations further time lag correlations are calculated between the key indices and atmospheric variables over the equatorial indo pacific oceans if type ii years derived by the wai are removed from the 34 year time series correlations between the toi and these variables increase appreciably now showing clearly the biennial character the analysis identifies a sequence of events involving biennial oscillation of the enso monsoon system from approximately jas 1 to jas o followed by intensification of the enso from jas o to november december january 1 the enso monsoon oscillation system is not sinusoidal but skewed to show the geographical patterns associated with the above sequence of events planar maps are presented of the lag correlation between the observed toi jas and i vertical velocity at the 500hpa level ii precipitation iii sea surface temperature sst and iv atmospheric sea level pressure distinct geographical distributions of the enso monsoon oscillation emerge in both the observations and model data one pattern is characterized by a horseshoe shape over the pacific which is generally symmetric around the equator but with geographical differences depending on location in the lag sequence the other pattern is a see saw shape primarily a standing oscillation located in the eastern south pacific and the indian oceans resembling the sea level pressure pattern found by trenberth and shea applying the lead lag relationship it is demonstrated that the sst over the central pacific four months ahead can be projected based on the toi jas conversely the intensity of the indian monsoon rainfall for non type ii years can be projected 15 months ahead by the sst over the eastern pacific ocean this indicates that the enso monsoon oscillation system is quasi periodic as opposed to irregular with a two year cycle this is clearly revealed with the removal of type ii years

a conceptual model of preferential flow systems in forested hillslopes evidence of self organization preferential flow paths are known to be important conduits of subsurface stormflow in forest hillslopes earlier research on preferential flow paths focused on vertical transport however lateral transport is also evident in steep forested slopes underlain by bedrock or till macropores consisting of decayed and live roots subsurface erosion surface bedrock fractures and animal burrows form the basis of a backbone for lateral preferential flow in such sites evidence from field studies in japan indicates that although individual macropore segments are generally 0 5 m in length they have a tendency to self organize into larger preferential flow systems as sites become wetter staining tests show clear evidence of interconnected macropore flow segments including flow within decayed root channels and subsurface erosion cavities flow in small depressions of the bedrock substrate fracture flow in weathered bedrock exchange between macropores and mesopores and flow at the organic horizon mineral soil interface and in buried pockets of organic material and loose soil here we develop a three dimensional model for preferential flow systems based on distributed attributes of macropores and potential connecting nodes e g zones of loose soil and buried organic matter we postulate that the spatially variable and non linear preferential flow response observed at our japan field site as well as at other sites is attributed to discrete segments of macropores connecting at various nodes within the regolith each node is activated by local soil water conditions and is influenced strongly by soil depth permeability pore size organic matter distribution surface and substrate topography and possibly momentum dissipation this study represents the first attempt to characterize the spatially distributed nature of preferential flow paths at the hillslope scale and presents strong evidence that these networks exhibit complex system behaviour

the role of the asian australian monsoon system in the onset time of el nino events abstract based on the time of first occurrence of a significant sea surface temperature anomaly ssta in the nino 3 4 area 5 s 5 n 170 120 w two types of el nino episodes can be identified the spring sp type in which the ssta first increased to greater than 0 5 c in april or may and the summer su type in which this threshold is first reached in july or august composites of the sstas for these two types of events during the period 1950 97 show that the sp su event is generally a stronger weaker warm episode in terms of the ssta amplitude and longer shorter in terms of the period during which the ssta is greater than 0 5 c before the occurrence of both types of el nino episodes the zonal wind anomalies over the western equatorial pacific are always westerly the east asian winter monsoon is also strong the difference between the two types is mainly in the timing of the occurrence of the westerly anomalies for the sp su events these anomalies extend to the date line by january may

dynamical and boundary forcing characteristics of regional components of the asian summer monsoon abstract in this paper the authors present a description of the internal dynamics and boundary forcing characteristics of two major subcomponents of the asian summer monsoon asm that is the south asian monsoon sam and the east southeast asian monsoon eam the description is based on a new monsoon climate paradigm in which the variability of asm is considered as the outcome of the interplay of a fast and an intermediate monsoon subsystem under the influence of slow external forcings two sets of regional monsoon indices derived from dynamically consistent rainfall and wind data are used in this study results show that the internal dynamics of sam are representative of a classical monsoon system in which the anomalous circulation is governed by rossby wave dynamics where anomalous vorticity induced by an off equatorial heat source is balanced by the advection of planetary vorticity on the other hand the internal dynamics of eam are characterized by a hybrid monsoon system featuring m

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

interannual variability of the onset of the indian summer monsoon and its association with atmospheric features el nino and sea surface temperature anomalies abstract the long term mean date of the monsoon onset over kerala mok varies between 30 may and 2 june according to different estimates with a standard deviation of 8 9 days the earliest date of mok and the most delayed one during the last 100 years differ by 46 days 7 may and 22 june respectively mok switches on a spatially large and intense convective heat source over south asia lasting from june to september whose moisture supply is made available through the cross equatorial low level jet stream superposed epoch analysis of 10 years of outgoing longwave radiation olr data shows that mok is a significant stage in the evolution of the olr field in the tropics of the eastern hemisphere at the time of mok there is increased convection in a band about 5 10 degrees wide meridionally extending from the south arabian sea to south china and convection is suppressed all around particularly in the western pacific ocean in 1983 when mok was delayed by about 3 pentads olr data showed that the

impacts of the indian ocean on the indian summer monsoon enso relationship this study investigates the impacts of the indian ocean on the relationship between the indian summer monsoon and the el nino southern oscillation enso through numerical simulations with a coupled atmosphere ocean general circulation model and atmospheric general circulation model agcm experiments with specified sea surface temperature sst and surface heat flux shf forcing previous studies have shown that this particular coupled model captures many aspects of the observed indian summer monsoon enso relationship however it is found that when the indian ocean is decoupled from the atmosphere the indian monsoon enso relationship reverses this change is linked to the relationships between surface evaporation surface wind and sst in the north indian ocean in the coupled case surface evaporation anomalies are positively correlated with surface wind anomalies during april june and are of the same sign as sst anomalies during july september in the decoupled indian ocean case surface evaporation anomalies are of the same sign as surface wind anomalies during the entire april september period numerical experiments with an agcm were performed with sst or shf anomalies specified in the tropical indian pacific ocean tropical pacific ocean only and tropical indian ocean only these experiments confirm the importance of local coupled air sea feedback in the indian ocean for a proper simulation of the indian monsoon enso relationship

development of tectonic cyclothems in rift pull apart and foreland basins sedimentary response to episodic tectonism the thickest part of asymmetric rift pull apart and foreland basin fills commonly consists of large scale hundreds to thousands of metres thick tectonically generated cyclothems of fine grained marine lacustrine or longitudinal fluvial deposits and coarse grained transverse braid plain or alluvial fan deposits the appearance of coarse clastics in these basin fills is typically noted as the time of tectonically rejuvenated source area uplift based on the conceptual tie between relief and coarse grain size and on the application of the davis theory of landform development we propose the opposite interpretation that the commencement of fine grained sedimentation above coarse grained deposits in a tectonic cyclothem is the best indicator of renewed tectonic activity this reinterpretation is more consistent with 1 modern examples 2 the consideration of source area and sedimentary basin geomorphology 3 the disparity between the reaction rates of the various environments to subsidence 4 the disparity between the rates of tectonic uplift and erosion and 5 the controls on elastic wedge progradation in our model extensive coarse grained clastic wedge progradation is an indicator of tectonically quiescent phases

an ocean atmosphere interaction mechanism for the active break cycle of the asian summer monsoon a typical active break cycle of the asian summer monsoon is taken as beginning with maximum sst pentad 0 over the north bay of bengal when the oceans to its west and east from longitude 40 160 e and between latitudes 10 and 25 n area a also has maximum sst during this pentad the recently found cold pool of the bay of bengal between latitudes 3 n and 10 n has its minimum sst an area of convection takes genesis over the bay of bengal immediately after pentad 0 in the zone of large sst gradient north of the cold pool and it pulls the monsoon low level jetstream llj through peninsular india convection and the llj westerlies then spread to the western pacific ocean during pentads 1 4 taken as the active phase of the monsoon during which convection and llj have grown in a positive feed back process the cyclonic vorticity to the north of the llj axis is hypothesized to act as a flywheel maintaining the convection during the long active phase against the dissipating effect of atmospheric stabilization by each short spell of deep convection by the end of pentad 4 the sst over area a has cooled and the convection weakens there when the llj turns clockwise over the arabian sea and flows close to the equator in the indian ocean a band of convection develops at pentad 5 between the equator and latitude 10 s over the indian ocean and it is nourished by the cyclonic vorticity of the llj now near the equator and the moisture supply through it this is taken as the break monsoon phase lasting for about three to four pentads beginning from pentad 5 of a composite active break cycle of 40 day duration with reduced wind and convection over the area a during the break phase solar radiation and light winds make the sst there warm rapidly and a new active break cycle begins sst convection llj and the net heat flux at the ocean surface have important roles in this new way of looking at the active break cycle as a coupled ocean atmosphere phenomenon

high resolution correlation of the upper cretaceous stratigraphy between the book cliffs and the western henry mountains syncline utah u s a abstract exposures of upper cretaceous strata in the book cliffs have played a key role in the formulation of modern sequence stratigraphic concepts and yet correlations with time equivalent strata in nearby regions remain uncertain resulting in an incomplete understanding of regional paleogeography this study presents detailed high resolution correlations of the upper cretaceous stratigraphy between the book cliffs the wasatch plateau and the western henry mountains syncline in utah with emphasis on the campanian interval two newly acquired measured vertical sections at coal canyon near green river in the book cliffs and blind trail in the henry mountains inform the correlations which also incorporate the substantial body of previous research correlations are further constrained by vertical and lateral facies stacking patterns and changes in sediment dispersal directions at discrete stratigraphic horizons derived from paleocurrent measurements much of the campanian succession can be characterized as a single low frequency third order depositional sequence within which are nested numerous high frequency sequences while it is not possible to correlate every high frequency sequence recognized in individual outcrop areas we define four intervals numbered 1 4 in ascending stratigraphic order that we correlate across the entire region interval 1 basal campanian is represented by initially deltaic and later wave dominated shoreface strata of the star point sandstone and equivalent basal muley canyon sandstone interval 2 lower campanian comprises coastal plain facies passing eastward into shallow marine strata of the lower blackhawk formation and equivalent muley canyon sandstone interval 3 lower to mid middle campanian comprises a thick aggradational stack of coastal plain fluvial strata that pass eastward into coastal and shallow marine facies blackhawk formation and equivalent masuk formation interval 4 overlying a major facies dislocation third order sequence boundary comprises amalgamated sheet fluvial deposits of the lower castlegate sandstone and equivalent tarantula mesa sandstone during the early to middle campanian the northern wasatch plateau and western henry mountains regions were along depositional strike with respect to one another the book cliffs near green river were located obliquely down depositional dip from the western henry mountains region during the campanian these new correlations and the improved understanding of paleogeography that derive from them have the potential to inform basin scale stratigraphic interpretations to a greater extent than has been hitherto possible

evolution and variability of the asian monsoon system state of the art and outstanding issues the asian monsoon is comprised of the indian and east asian subsystems these two components are linked to one another in varying degrees by regions of strong sensible heating indo asian landmass and strong latent heat export the western pacific warm pool and the southern subtropical indian ocean variability within the indian and east asian subsystems interactions among them and the extent to which they interact with other climate phenomena e g enso are current topics of modern and paleoclimate research this work provides an overview of past and current paleomonsoon research on tectonic to interannual time scales with a primary focus on marine sediment records while past and current work has contributed greatly to our understanding of paleomonsoon variability at all time scales additional efforts are required to make further progress in two critical areas 1 additional efforts are needed in terms of proxy development and evaluation requiring concerted efforts at long term sediment trap deployments in key monsoon influenced regions as well as development of adequate and widely available core top databases these are necessary to assess the impact of modern oceanographic and seafloor processes on potential monsoon proxies 2 additional effort is also needed in acquiring a sufficient geographic distribution of downcore records to assess linkages among the subsystems and their role in the context of extratropical climate change these records should have high sedimentation rates including varved sections this requires substantial survey support to identify the most appropriate coring and drilling targets c 2004 elsevier ltd all rights reserved

monsoonal precipitation in the paleo tethys warm pool during the latest permian abstract simulations of the late permian 251 ma are analyzed with respect to the northern hemispheric pangean monsoon we find that the presence and spatial distribution of the warm pool and not land sea temperature differences are the primary forcing agents for the monsoon the land sea temperature gradient as a monsoonal mechanism is tested by eliminating the cathyasian peninsula and is found to have little impact on the spatial character of the monsoon furthermore the response of the monsoon to the warm pool was tested by removing all paleo tethys equatorial islands which allows the warm pool to expand and migrate westward thus shifting the pattern of monsoonal precipitation given that paleogeography changes through time these results have important implications for the migration and strength of the tropical monsoon over geologic time additionally different co2 regimes are presented in which a 10 fold change in forcing produces diverging climates and therefore different warm pool and monsoon locales tropical and equatorial ocean currents impact the seasonal progression and location of the warm pool and atmospheric mass flux for the monsoonal regime is characterized and shown to change with warm pool movement experiments were conducted using the low resolution version of community climate system model version 3 ccsm3 in both coupled and fixed sea surface temperature sst context for validation purposes a modern control is briefly presented with observations and is shown to represent both the spatial and seasonal progression of the indian monsoon

subseasonal variations in spatial signatures of enso on the indian summer monsoon from 1901 to 2009 correlations of 1 by 1 seasonal rainfall with pacific sea surface temperatures ssts reveal spatially distinct teleconnections between el nino southern oscillation enso and indian summer monsoon rainfall over the full monsoon season as well as three subseasons over the full season june september pacific ssts correlate with rainfall in western india more than that in eastern india this spatial signature shifts as the monsoon progresses through early june middle or peak july august and late september subseasons specifically a 1 c cooling of the central equatorial pacific i e la nina conditions can result in the following 70 100 increase in precipitation in north central indian and the indo gangetic plains during the early season 30 80 increase peak season precipitation in south central india and northwestern rajasthan and 60 100 increase in late season precipitation in northern northwestern and central india furthermore the spatial signatures between la nina and el nino are asymmetric in that for a particular location the enhancement and suppression of rainfall associated with la nina and el nino conditions respectively are not equal el nino suppresses peak season rainfall in the south central and northwestern rajasthan regions more than la nina enhances it but the opposite occurs during the late season in northern northwestern and central india additionally the correspondence of minima maxima in anomalies of velocity potential aloft with maxima minima at 925 mb and with positive negative surface pressure anomalies suggests that anomalous subsidence ascent occurs in july september during el nino la nina times in the early season however patterns of velocity potential composites suggest a region of descent ascent over the western equatorial indian ocean along with a region of ascent descent over the indian subcontinent that exists only during the early season but not during the peak or late season these patterns are consistent with the hypothesis that local hadley cell circulation affects pressure and thus rainfall during the early season but that a larger scale mechanism such as eastward or westward shifts in the walker circulation may be more responsible for teleconnections seen throughout the remainder of the season these findings indicate that focusing monsoon forecasting efforts on these regions and on subseasonal periods while incorporating enso asymmetries will yield useful and skillful regional forecasts compared to the declining utility and skill of all india summer monsoon rainfall