atmospheric processes governing the changes in water isotopologues during enso events from model and satellite measurements enso el nino southern oscillation has profound effects on the global water cycle which can be examined at the process level by investigating the associated water isotopologues many isotope based studies are aimed at understanding enso variability in the tropics however focusing principally on near surface processes and isotopologue signals the goal of the present study is to investigate the atmospheric processes governing the changes in the isotopic composition of water vapor both near the surface and at midtroposphere in the pacific region during enso events using a combination of remote sensing data and model simulations for the lower atmosphere i e 1000 hpa our results show that rainout processes less rain reevaporation of falling droplets and increase of convective updrafts and diffusive exchange within the convective systems contribute to the isotope amount effect and isotopically deplete the water vapor during wet conditions in agreement with previous studies however we find that the enso associated isotopic signal in the midtroposphere i e 500 hpa diverges from the near surface response analysis suggests that transport of enriched water vapor from lower atmospheric layers through convective updrafts controls the enrichment of midtropospheric water vapor over the pacific ocean in the observations a strong positive correlation between the increase of convective precipitation and the isotopic composition of water vapor clearly points to such a mechanism r of 0 7 0 8 in the central pacific and 0 5 0 6 in the west pacific model results confirm this mechanisms though producing slightly lower correlation values with r values of 0 6 in the central pacific and 0 5 in the west pacific however the distinction between convective and stratiform precipitation remains a result of model dependent parameterization our analysis suggests that two issues should be investigated in more detail in further studies 1 the equilibrium and disequilibrium between rain droplets and surrounding vapor for convective and stratiform precipitation and 2 different convection schemes in the different isotopic general circulation models gcms describing the triggering of convection and uplift of lower layer air to higher layers ideally such a comparison of different isotopic gcms can provide us with an interesting benchmark test for the performance of the different convection schemes during enso and can help to disentangle the importance of the different processes contributing to the amount effect

geographic variability in the export of moist static energy and vertical motion profiles in the tropical pacific 1 column integrated moist static energy mse budgets were calculated using daily data from three reanalyses 1998 2001 and isccp radiative cooling the mse export by the circulation was separated into vertical and horizontal mse advection components in order to examine how observationally derived vertical motion profiles affect gross moist stability calculations in a 2000 km wide region in the central eastern pacific itcz vertical motions import mse implying a negative gross moist stability horizontal mse advection is negative and of similar magnitude to vertical mse advection in rainy regions geographic differences in export of mse by the vertical circulation are primarily due to differences in the shape of the vertical motion profile in the west pacific warm pool rainy regions mean horizontal convergence extends up to 300 mb while in parts of the pacific itcz where meridional sst gradients are strong the vertical motion profile is bottom heavy with convergence below 800 mb and divergence above on daily timescales the mode of vertical motion variability has little dependence on precipitation rate and is consistent with observed regional differences in the vertical structure of trmm pr reflectivities

oxygen and hydrogen isotopes in the hydrologic cycle changes of the isotopic composition of water within the water cycle provide a recognizable signature relating such water to the different phases of the cycle the isotope fractionations that accompany the evaporation from the ocean and other surface waters and the reverse process of rain formation account for the most notable changes as a result meteoric waters are depleted in the heavy isotopic species of h and o relative to ocean waters whereas waters in evaporative systems such as lakes plants and soilwaters are relatively enriched during the passage through the aquifers the isotope composition of water is essentially a conservative property at ambient temperatures but at elevated temperatures interaction with the rock matrix may perturb the isotope composition these changes of the isotope composition in atmospheric waters surface water soil and groundwaters as well as in the biosphere are applied in the characterization of hydrological system as well as indicators of paleo climatological conditions in proxy materials in climatic archives such as ice lake sediments or organic materials

taking the pulse of the tropical water cycle climate records from tropical ice cores from the andes have been interpreted in terms of temperature changes similar to records from the polar regions in his perspective hoffmann 1 reviews recent evidence that rather than exclusively temperature the andean records track changes in precipitation in conjunction with other records such as corals and with global climate models the ice cores can be used to reconstruct the hydrological cycle however more precisely dated records are needed to extend this reconstruction beyond recent decades 1 http www sciencemag org cgi content full 301 5634 776

lessons learned from oxygen isotopes in modern precipitation applied to interpretation of speleothem records of paleoclimate from eastern asia abstract variability in oxygen isotope ratios collected from speleothems in chinese caves is often interpreted as a proxy for variability of precipitation summer precipitation seasonality of precipitation and or the proportion of 18o to 16o of annual total rainfall that is related to a strengthening or weakening of the east asian monsoon and in some cases to the indian monsoon we use modern reanalysis and station data to test whether precipitation and temperature variability over china can be related to changes in climate in these distant locales we find that annual and rainy season precipitation totals in each of central china south china and east india have correlation length scales of 500 km shorter than the distance between many speleothem records that share similar long term time variations in 18o values thus the short distances of correlation do not support though by themselves cannot refute the idea that apparently synchronous variations in 18o values at widely spaced 500 km caves in china are due to variations in annual precipitation amounts we also evaluate connections between climate variables and 18o values using available instrumental measurements of 18o values in precipitation these data from stations in the global network of isotopes in precipitation gnip show that monthly 18o values generally do not correlate well with either local precipitation amount or local temperature and the degree to which monthly 18o values do correlate with them varies from station to station for the few locations that do show significant correlations between 18o values and precipitation amount we estimate the differences in precipitation amount that would be required to account for peak to peak differences in 18o values in the speleothems from hulu and dongge caves assuming that 18o scales with the monthly amount of precipitation or with seasonal differences in precipitation insofar as the present day relationship between 18o values and monthly precipitation amounts can be applied to past conditions differences of at least 50 in mean annual precipitation would be required to explain the 18o variations on orbital time scales which are implausibly large and inconsistent with published gcm results similarly plausible amplitudes of seasonal cycles in amounts or in seasonal variations in 18o values can account for less than half of the 4 5 difference between glacial and interglacial 18o values from speleothems in china if seasonal cycles in precipitation account for the amplitudes of 18o values on paleoclimate timescales they might do so by extending or contracting the durations of seasons a frequency modulation of the annual cycle but not by simply varying the amplitudes of the monthly rainfall amounts or monthly average 18o values amplitude modulation allowing that several processes can affect seasonal variability in isotopic content we explore the possibility that one or more of the following processes contribute to variations in 18o values in chinese cave speleothems different source regions of the precipitation which bring different values of 18o in vapor different pathways between the moisture source and the paleorecord site along which exchange of 18o between vapor surface water and condensate might differ a different mix of processes involving condensation and evaporation within the atmosphere or different types of precipitation each may account for part of the range of 18o values revealed by speleothems and each might contribute to seasonal differences between past and present that do not scale with monthly or even seasonal precipitation amounts

pre pleistocene glaciation on earth implications for climatic history of mars the history of ice ages on earth extending back more than 2 ga 109 years has been established by the recognition in strata of many ages of the assemblage of erosional features and deposits generated by glacial activity the most useful indicators are widespread diamictite striated and faceted clasts polished and striated pavements and laminites containing dropstones inferred to be ice rafted the chronology of ancient glaciation is limited by our ability to recognize the results of glacial activity in an incomplete geologic record and by the age resolution attainable with available dating methods ice ages are currently known from the early proterozoic 2 5 2 1 ga ago several intervals in the middle to late proterozoic 1 0 0 57 ga the late ordovician to late silurian 440 415 ma or 106 years possibly latest devonian 360 345 ma permo carboniferous 335 245 ma and late cenozoic 26 ma ago to the present however the timing of pre phanerozoic ice ages occurring before 0 57 ga ago is known only approximately and glacial events would have been shorter than is suggested by the bracketing ages a generally warm climate seems to have prevailed for the remainder of earth history although mesozoic cenozoic seismic stratigraphic evidence suggests that a small ice sheet may have been a persistent feature near the south pole throughout the last 500 ma terrestrial climatic fluctuations occur on several time scales the occurence of ice ages on a time scale of 108 109 years and possibly higher frequency fluctuations 106 107 years appears to be controlled by changes in solar output and atmospheric composition and by the rearrangement of continents and oceans as a result of the motion of lithospheric plates climatic changes on a time scale of 104 105 years are driven by perturbations of the earth s orbital parameters the principal evidence suggesting that significant climate changes have occured on mars consists of widespread dry channels 3 5 0 5 ga and of geologically young dust ice layered terrains in the polar regions 10 ma by analogy with the earth polar layered terrains have probably existed episodically on mars for a considerable time although there is little direct evidence for this factors affecting a potential sedimentary record are the degree to which ice sublimed or melted the effectiveness of eolian destruction of layering and in contrast to the present polar terrains the tendency for ice to flow and slide over its substrate as on earth climate changes on mars have probably been induced by the long term evolution of the atmosphere by changes in solar luminosity and by variations in orbital parameters major tectonic events may have affected martian climate through changes in planetary obliquity

numerical climate modeling a frontier in petroleum source rock prediction results based on cretaceous simulations organic productivity and preservation are primary controls of the distribution of petroleum source beds both organic productivity and preservation are in part a function of geographic setting and climate therefore the prediction of paleoclimates is a major frontier in petroleum source rock prediction a climate model based on the fundamental laws thought to govern atmospheric circulation is applied here to the prediction of upwelling regions associated with very high productivity and bottom conditions that may become anoxic despite a high oxygen supply the potential and limitations of climate modeling in the prediction of upwelling regions are examined by 1 demonstrating the ability of the model to predict present day winds and upwelling regions 2 demonstrating t at the model and the location of upwelling regions is sensitive to geography continental positions sea level and topography and 3 investigating whether the model sensitivity to past geographies is realistic i e if predicted upwelling regions for the cretaceous period correspond to source rock localities the model predictions of ocean and coastal upwelling compare very favorably with present day observations and with estimates of primary productivity the location of middle latitude and high latitude upwelling locations are sensitive to model specified geography the location of low latitude upwelling is less sensitive to changes in global geography if coastlines are oriented appropriately despite some limitations a comparison of source rock localities with model predictions is promising the results of these studies suggest that numerical climate modeling is a potential tool in petroleum source rock prediction

hydrological and vegetation shifts in the wallacean region of central indonesia since the last glacial maximum abstract precipitation is the most important variable of indonesian climate yet there are substantial uncertainties about past and future hydroclimate dynamics over the region this study explores vegetation and rainfall and associated changes in atmospheric circulation during the past 26 000 years in wallacea a biogeographical area in central indonesia wedged between the sunda and sahul shelves and known for its exceptionally high rainforest biodiversity we use terrestrial plant biomarkers from sediment cores retrieved from mandar bay off west sulawesi to reconstruct changes in wallacean vegetation and climate since the last glacial maximum lgm enriched leaf wax carbon isotope 13cwax values recorded in mandar bay during the lgm together with other regional vegetation records document grassland expansion implying a regionally dry and possibly more seasonal glacial climate depleted leaf wax deuterium isotope dwax values in mandar bay during the lgm and low reconstructed precipitation isotope compositions from nearby sites reveal an intensified austral asian summer monsoon circulation and a southward shift of the mean position of the intertropical convergence zone likely due to strong southern hemisphere summer insolation and the presence of large northern hemisphere ice sheets mandar bay 13cwax was anti correlated with dwax during the lgm and the last deglaciation but was positively correlated during most of the holocene indicating time varying controls on the isotopic composition of rainfall in this region the inundation event of the sunda shelf and in particular the opening of the java sea and karimata strait between 9 4 and 11 1 thousand years ago might have provided new moisture sources for regional convection and or influenced moisture source trajectories providing the trigger for shifts in atmospheric circulation and the controls on precipitation isotope compositions from the lgm to the holocene

petrophysical properties composition and deterioration of the calatorao biogenic stone case of the sculptures masonry of the valley of the fallen madrid spain the huge sculptures placed outdoors in the valley of the fallen memorial park el escorial madrid made with blocks of black limestone from calatorao zaragoza spain blcz and disposed on a concrete core exhibit weathering traces flaking saline efflorescence and falling fragments currently represent a danger for visitors frost action is important in the valley of the fallen by the large number of freeze thaw cycles produced during sculptures live under a temperate mediterranean climate with severe seasonality the formation of fissures facilitates the water transport within the rock and the salt and ice induced deterioration temperate climates with frequent freezing and thawing cycles can be the most effective drivers of the visible physical weathering in order to propose a suitable weathering model collected black limestones from sculptures and calatorao quarries were analyzed by optical microscopy environmental scanning electron microscopy with energy dispersive spectrometry esem eds inductively coupled mass spectrometry icp ms and x ray diffraction mercury intrusion porosimetry mip nitrogen absorption and helium pycnometry techniques were used for pore analyses of the blcz micro blocks 10 10 10 cm described in terms of pore size distribution pore volume and specific surface area the appreciable amount of organic matter was isolated by solvent extraction acid treatment flotation and perborate degradation followed by gas chromatography mass spectrometry gc ms analytical pyrolysis py gc ms fourier transformed infrared spectroscopy and raman techniques both weathered and fresh blcz samples contained more than 90 calcite shells with circa 10 of pyrite fresh samples or iron hydroxides weathered samples quartz grains claystone and fossil organic matter consisting of a condensed matrix with polyalkyl chains and polycyclic methoxyl lacking aromatic structures the petrophysical analyses revealed volumes of pores sized 0 025 m obtained by n2 adsorption of 3 18 10 3 cm3 g 1 while the measured porosity by mip in the pore range from 0 005 to 200 m was 3 30 10 3 cm3 g 1 these data could be explained by the existence of clay minerals and organic matter in the pore system less than 50 nm of diameter concerning blcz deterioration it was found that the porous framework of blcz was filled with sulphates formed from artificial cement observed in the sculptures inside trough a testing hole and from its intrinsic pyrite the results suggested that although biological processes were not major agents in rock deterioration there was also weak compatibility between sculptures constituents limestone concrete and oxidized iron clamps which under continental mediterranean conditions were continuously releasing weathering compounds accelerating disruption of the cut stone sculptures

stable isotopic variations in west china a consideration of moisture sources 1 in this study individual precipitation samples collected over 2 years at stations in different climatic regions of west china tibetan plateau region tianshan region and altay were analyzed for the stable isotopes of precipitation to improve our understanding of how vapor transport impacts the modern stable isotopic distribution our results identify regional patterns in both 18o and deuterium excess d excess defined as d 8 18o and in particular we have identified the northward maximum extent of the southwest monsoon over the tibetan plateau this demarcation is also the boundary for the fractionation effect of temperature on stable isotopes in precipitation the patterns we have identified are as follows 1 in the southern tibetan plateau along the southern slope of the himalayas our results show a distinct seasonality for both 18o and d excess as a result of the shift of summer monsoon moisture and winter westerly moisture transport the signals of 18o in the western tibetan plateau reveal that the region receives southwest monsoonal moisture in the east of the plateau stable isotopic variation shows alternation between monsoon intrusion and recycling of northern moisture 2 in contrast in tianshan there is an apparent temperature effect in 18o with enriched values occurring in summer and depleted values occurring in winter seasonal d excess values opposite to those observed in the southern tibetan plateau are controlled by differing seasonal evaporation conditions 3 in altay the most northern mountain region the seasonal 18o shows the same variation with that in tianshan region however d excess shows no apparent seasonal variation

rainfall patterns and the distribution of coals and evaporites in the mesozoic and cenozoic abstract paleoclimatologists have adequately demonstrated over the last twenty years that the distribution of climatically sensitive sediments can be related to present day climatic zones that are roughly parallel to latitude for example coals were deposited at paleolatitudes that correspond to the present day rainy zones at the equator and at about 55 n and 55 s indicating that those zones were present in the past from this it can be concluded that atmospheric circulation has not been radically different from its present configuration despite some apparently great differences in some climatic parameters such as the equator to pole temperature gradient nevertheless the zonal model for predicting the distribution of climatically sensitive sediments is not wholly adequate although general atmospheric circulation may not have been radically altered from its present pattern it would have differed in some respects because the paleogeography was different from the present geography therefore we have constructed what we believe are more realistic maps of the distribution of rainfall through time these maps are based on maps of atmospheric circulation that have been successfully used to predict the distribution of some petroleum source beds and phosphorites we have compared the predicted distribution of rainfall to the distribution of coals and evaporites for each of seven geologic stages the circulation rainfall maps were more successful than the zonal model for predicting the distribution of evaporites and coals for times when the paleogeography would have maximized the development of a monsoonal circulation which most effectively disrupts the general zonal pattern for times when a monsoonal circulation would not have been important the zonal model adequately predicted the distribution of these rocks

depositional model for understanding geometry of cretaceous coals major coal seams rock springs formation green river basin wyoming the upper cretaceous rock springs formation of the green river basin ranges from marine strata of prodelta origin to marginal marine and nonmarine equivalents of delta front and delta plain fluvial strata coal exploration drill holes measured sections and underground mine data have been analyzed to reconstruct the depositional setting of the rock springs formation extensive sheet sandstones are inferred to be delta front deposits reflecting the cuspate to arcuate geometry of wave dominated deltaic deposits extensive coal deposits up to 22 ft 6 7 m thick that developed on top of delta front sandstones extend for 15 mi 24 1 km along depositional dip and 36 mi 58 km along depositional strike these coal deposits are referred to as type a coal seams coal deposits 1 17 ft 0 3 5 2 m thick that developed in upper delta plain fluvial environments are less than 20 mi 32 2 km in length these deposits are referred to as type b coal seams type c seams are persistent thin coal deposits 1 8 ft 0 3 2 4 m thick developed on top of delta plain fluvial deposits less than 25 mi 40 2 km in length and they mark the delta lobe abandonment phase approximately 15 major coal zones exist in the rock springs formation the geometry of types a b and c reflects a genetic relationship to both deltaic and fluvial units in the marginal marine and nonmarine components of the rock springs formation a model for predicting coal seam thickness and continuity is believed to be applicable to additional exploration in the green river basin and in other cretaceous coal bearing basins in the western interior

underlying issues on the selection use and conservation of building limestone an argument is presented that despite popular assumptions many limestones especially the wide range of clastic and in general granular limestones do not decay in a steady and predictable pattern in response to slow dissolution instead these stones especially when used in construction in polluted environments invariably decay episodically through physical breakdown most commonly this is accomplished through a variety of salt weathering mechanisms that if unconstrained can lead to the rapid catastrophic decay of building blocks and their complete loss a process that has driven the extensive programmes of stone replacement that are typical of buildings constructed of these stones in polluted environments especially those rich in sulphur and particulates the most common constraint on accelerated decay has been the rapid development of gypsum crusts that for example could rapidly heal the scars left by contour scaling it is ironic therefore that any reduction in pollution could conceivably lead to increased erosion by retarding this healing process because of this temporal variability of decay and its translation into spatial complexity it is important that further research is undertaken to understand controls on the decay of these important building stones so that future conservation strategies can be appropriately informed on the predictability of decay and the role

palaeoclimatic significance of changes in clay mineralogy across the jurassic cretaceous boundary in england and france abstract clay mineralogical changes across the jurassic cretaceous boundary from the northern to the southern part of western europe show similar patterns in the mudrocks exposed on the yorkshire coast the paralic sediments of the dorset wessex basin and the jura and vocontian trough of s e france this comprises a change from smectite poor sediments in the jurassic with correspondingly abundant illite and kaolinite to sediments with abundant smectite in the jurassic cretaceous boundary beds depleted in kaolinite this change occurs in the oxfordian in the south to latest volgian in the north of the study area kaolinite reappears in abundance in the late ryazanian or stratigraphic equivalent in all the locations studied comparison with other climatic indicators and other areas suggest that these variations can be ascribed to a phase of latest jurassic earliest cretaceous aridity the onset of which appears to be diachronous across w europe possible causes for the climatic change towards aridity are examined the orographic effect of mountains or plateaus to the east of the study area is considered most likely

artificial weathering of spanish granites subjected to salt crystallization tests surface roughness quantification for hundreds of years two types of granite zarzalejo and alpedrete from the madrid region spain have been extensively used as building stones fresh specimens of both stone types have been sampled from their respective quarries and subjected to sodium sulphate salt crystallization test sct the resulting physical and chemical weathering patterns have been characterized by polarized light optical and environmental scanning electron microscopy water absorption under vacuum conditions and mercury intrusion porosimetry techniques were used to determine the pre and post sct porosity and pore size distribution the following non destructive techniques were performed to assess stone durability and decay ultrasound velocity us and surface roughness determination sr of intra and inter granular quartz feldspar and biotite minerals at the centre as well as at the corners and edges of specimen surfaces before the sct us values were lower and sr values higher in zarzalejo zar than alpedrete alp granite after sct the us values declined while sr rose in both types of granites with greater average differences in zar than alp for both parameters feldspar and biotite and their inter granular contacts were found to be the weakest and therefore the most decay prone areas of the stone the initial sr parameters were generally higher and rose more steeply after sct at the corners and around the edges of the specimens while behaviour was found to be similar in the two types of granite variations were greater in zar the less durable and more decay prone of the two surface roughness measurement of mineral grains in granite stones is a very useful in situ non destructive technique for quantifying salt crystallization mediated physical and chemical weathering the resulting quantification of decay and of related durability provides insight into the future behaviour of this type of stone commonly used in historic buildings

oxygen isotope and paleobotanical estimates of temperature and δ18o latitude gradients over north america during the early eocene empirical estimates of climate parameters such as mean annual temperature mat are essential to describe both ancient climate and to ground truth climate model simulations of past climates in terrestrial settings no single proxy record is able to provide detailed temporal yet geographically widespread information and it thus becomes essential that paleoclimatic information obtained from different proxies be comparable as an example of how to compare estimates and to illustrate what can be learned by doing so we measured oxygen isotope ratios of phosphate in the tooth enamel of fossil mammals and the body scales of freshwater fish in order to estimate the mean annual temperature mat in which they lived the samples were collected from paleogene rocks of the bighorn green river and powder river basins of wyoming earliest eocene samples provide mat estimates that are similar to mat estimates for the same times and areas obtained from leaf margin analysis furthermore isotopic data from the paleocene eocene thermal maximum petm which has not yet yielded fossil floras indicate a significantly higher mat of 26 c we also used temperature estimates obtained by both methods to investigate paleoelevation and to reconstruct geographic patterns of mat over north america for the early eocene larger laramide basins have higher temperatures and lower inferred elevations compared to associated volcanic highlands where cooler temperatures are consistent with substantial elevations in turn latitudinal gradients in temperature indicate that warming centered on polar regions played an important role during the eocene hothouse lastly we show that the reconstructed eocene relation between oxygen isotope ratios of precipitation and mat is significantly different from the modern relation between these two variables because the relation has changed over time the modern correlation should not be used to estimate paleo mat from measurements of oxygen isotope ratios in fossil material

rock varnish in the sonoran desert microbiologically mediated accumulation of manganiferous sediments rock varnish occurs in virtually all environments most commonly in arid and semi arid climates including antarctica rock varnish consists of thin layers of intimately mixed aeolian and chemical sediments often showing botryoidal and more rarely stromatolite like morphologies typical rock varnish samples collected at twin peak mountain park near phoenix arizona consist of abundant quartz with plagioclase illite and a mixed layer fe clay mineral probably corrensite eds sem bse and tem analyses revealed that the typical mn fe minerals occur as minute particles some of these particles and other mineral grains are attached to filaments xrd and electron diffraction showed that the mn fe bearing particles are poorly crystalline the filaments based on morphological criteria are virtually indistinguishable from fungal filaments most filaments are fragments probably broken by scraping during sample collection coccoid and rod shaped forms resembling cyanobacteria and other bacteria respectively are also present unlike definitive minerals these filaments disintegrated in the concentrated energy of the sem electron beam at the instrumental and experimental conditions used in addition no filamentous rod shaped or coccoid forms were observed in samples hydrolysed with 6 n hcl for 24 h at 100 c bacteria and fungi in powdered rock varnish were cultured on four media incubated aerobically in the dark at 25 c the culture media yielded dense growths of spore forming bacteria and filamentous fungi one fungus and two bacillus isolates oxidized and concentrated manganese control experiments revealed that fungi and bacteria are present on and below the surfaces of rock varnish free and hydrolysed peptide protein bound amino acids were identified in the rock varnish amino acids showed virtually no racemization with the exception of d l asp 0 1 relatively high molecular weight humic matter was also separated from the rock varnish high resolution mass spectrometry revealed non hydrocarbon moieties similar to a suwannee river fl humic acid standard micro organisms and their original biochemical compounds do not seem to be preserved for long in the accreting varnish layer the studies showed that the filaments helped to trap mineral particles of rock varnish and that bacteria and fungi abetted mn concentration some structures in the layers of rock varnish resemble stromatolites and present definitions would allow them to be termed as such

glacial aridity in central indonesia coeval with intensified monsoon circulation abstract the last glacial maximum was cool and dry over the indo pacific warm pool ipwp a key region driving global oceanic atmospheric circulation both low and high latitude teleconnections with insolation ice sheets and sea level have been suggested to explain the pervasive aridity observed in paleoecological and geomorphic data however proxies tracking the h and o isotopic composition of rainfall e g speleothems sedimentary biomarkers suggest muted aridity or even wetter conditions than the present complicating interpretations of glacial ipwp climate here we use multiproxy reconstructions from lake sediments and modern rainfall isotopic measurements from central indonesia to show that contrary to the classical amount effect intensified australian indonesian monsoon circulation drove lighter h and o isotopic composition of ipwp rainfall during the lgm while at the same time dry conditions prevailed precipitation isotopes are particularly sensitive to the apparent increase in monsoon circulation and perhaps also decreased moisture residence time implied by our data explaining contrasts among proxy records while illuminating glacial ipwp atmospheric circulation a key target for climate models

isotopic composition of salt efflorescence from the sandstone castellated rocks of the bohemian cretaceous basin czech republic the origin of sulphates in sulphate rich efflorescences on quartz sandstones with a clay matrix exposed in rural areas of the czech republic is interpreted based upon an isotopic study of s and o sulphates such as gypsum and or alums exhibit 34s ranging from 1 3 to 6 1 and 18o from 5 3 to 8 8 the low variability of s and o isotopes indicates a common source of the sulphur and a similar mode of sulphate formation atmospheric sulphates with a similar isotopic signature occur in the area due to the combustion of sulphurous coal in power plants located a few tens of kilometres from the sampling points the sulphates crystallize from supersaturated pore waters that represent atmospheric precipitation rich in sulphates having percolated through the porous sandstone system the previously proposed model of efflorescence growth that it is due to the oxidation of pyrite can be excluded due to both the rare occurrence of pyrite and also to its different isotopic signature 34s about 22 although gypsum prevails in the central and eastern part of the studied area the north and north west of the bohemian cretaceous basin the most polluted region exhibits a significant presence of alums nh4 or k nh4 rich formation of alums can be explained by the partial dissolution of clay minerals or feldspars present in the sandstone matrix release of alumina from these phases is facilitated by the low ph of the precipitation ph 4 4 5 and also locally by organic acids traces of which were found in the studied efflorescences by the use of infrared spectroscopy

paleoclimate of the kimmeridgian tithonian late jurassic world ii sensitivity tests comparing three different paleotopographic settings moore g t sloan l c hayashida d n and umrigar n p 1992 paleoclimate of the kimmeridgian tithonian late jurassic world ii sensitivity tests comparing three different paleotopographic settings palaeogeogr palaeoclimatol palaeoecol 95 229 252 topography and location of continents largely determine present day climate we conclude that in the geologic past paleotopographic expression was equally important however in the geologic record paleotopography is difficult to assess and compile because it is largely a self destructive environment without record and is rarely addressed in the literature an objective of this study is to test the sensitivity of paleoclimate to paleotopography by comparing three different late jurassic scenarios paleotopography influences many paleoclimate parameters to varying degrees to test the sensitivity of paleoclimate to modeled paleotopography for simulations incorporating a late jurassic reconstruction we ran three simulations using the same boundary conditions of paleogeography land and ocean and atmospheric co2 concentration 4x the pre lndustrial level 1120 ppm one simulation contained mountain ranges of variable height to 3 kin in another all the mountain ranges were reduced to 1 km highlands the third simulation used a constant 500 m height for all land grid cells the sensitivity tests indicate that paleotopography is an important boundary condition without realistic paleotopography flat or idealized continents surrounded by bodies of water do not produce realistic pateoclimate results we conclude that in paleogeographic reconstructions the location and extent of mountain ranges and highlands should be recognized and given suitable elevations consistent with their plate tectonic origins settings and geologic ages

efficacy of laser cleaning in the removal of biological patina on the volcanic scoria of the rock hewn churches of lalibela ethiopia the lalibela rock hewn churches are one of the most important religious pilgrimage sites in ethiopia these churches are carved from the scoriaceous basalt rock substrate which has been exposed to attack by biological agents with significant loss of surface material particularly the widespread growth of lichens and other microorganisms on the carved surfaces of the churches has proven to represent a substantial threat for the preservation of the site in this study laboratory tests have been conducted to assess the feasibility of using laser technology as an efficient cleaning method of biological patina from polymineralic stone substrates multi analytical techniques were applied for the characterization of the stone samples collected from two of the lalibela churches bete giyorgis and bete amanuel stone samples artificially inoculated with bacteria yeast fungi isolates and lichen encrusted samples were laser cleaned using uv and ir laser wavelengths the high content of fe and ti oxides and the high porosity have made the stone surfaces easily susceptible to low energy laser treatment results indicate that laser cleaning can be applied to polymineralic lithotypes and uv irradiation can successfully remove lichen colonies further studies need to be conducted to optimize the laser procedure in polymineralic high porosity stones

stable isotope evidence of dual arabian sea and bay of bengal vapour sources in monsoonal precipitation over north india abstract high resolution time series data of hydrogen d and oxygen 18o isotope values of precipitation have been generated for the first time at kolkata eastern india where the summer monsoon clouds from bay of bengal bob commence their journey over india use of a rayleigh cum two component mixing model and comparison of kolkata data with the international atomic energy agency iaea global network of isotopes in precipitation gnip data base of new delhi suggest that the precipitation at new delhi cannot be explained by simple continental effect of a bob vapour source alone traveling and raining successively along kolkata new delhi route it is necessary to invoke an admixture of 20 vapour originating from the arabian sea with the vapour coming from bob and finally causing summer monsoon rains at new delhi the findings have major implications to the regional water vapour budget over india

what was the surface temperature in central antarctica during the last glacial maximum abstract the temperature increase at vostok antarctica from the last glacial maximum to the present warm period is about 8 c based on the deuterium isotope profile the bore hole temperature temperature profile in the ice sheet indicates that the temperature difference may have been much larger about 15 c the temperature dependent gas occlusion process is the key to evaluate the two scenarios atmospheric air penetrates the porous firn layer of the ice sheet and gets trapped at the firn ice boundary consequently the air is younger than the surrounding ice when it gets enclosed in bubbles this age difference age between ice and enclosed gas is temperature and accumulation rate dependent therefore it is possible to estimate paleotemperatures from a known age we use the linkage between chronologies of ch 4 and water isotopes from byrd station and vostok to obtain an experimental age for vostok this experimental age is then compared to modeled age for the two temperature scenarios our results indicate that the temperature reconstruction deduced from the water isotopic composition is the more probable one

paleoclimate of the kimmeridgian tithonian late jurassic world i results using a general circulation model abstract the kimmeridgian tithonian 154 7 145 6 ma middle and late late jurassic was a time of expanded continental rifting increased sea floor spreading and a relatively high eustatic sea level stand these processes collectively caused the fragmentation and flooding of the megacontinent pangea as well as the alteration of the global paleoclimate using a version of the community climate model ccm from the national center for atmospheric research we report two kimmeridgian tithonian paleoclimate seasonal simulations with geologically inferred paleotopography one using a co 2 concentration of 280 ppm pre industrial level and the other 1120 ppm increasing the co 2 four fold warms virtually the entire planet the greatest warming occurs over the higher latitude oceans and the least over the equatorial and subtropical regions simulation of a warmer planet with an elevated greenhouse effect fits the distribution of paleoclimatically sensitive faunas floras and sedimentary rocks model results indicate that sea ice was restricted to the high latitudes of the boreal and austral seas making landfall only in restricted areas the trade winds bring heavy rainfall in december january february to eastern gondwana and in june july august to the tethys sea margins a strong june july august monsoon occurs over southeast asia the distribution of coals correlates to precipitation sufficient to maintain gymnosperm forests and coastal areas where water saturated sediments are a result of eustatic high stands of sea level evaporites are localized to areas of negative precipitation evaporation runoff is restricted to regions of intense precipitation overall the 1120 ppm co 2 simulation provides a reasonable paleoclimate for the kimmeridgian tithonian and provides a standard until a ccm with oceanic heat transport a coupled atmospheric oceanic model or one with a finer grid cell configuration is available the results need further scrutiny in areas with more detailed geologic information

magnitude of isotope temperature scaling for interpretation of central antarctic ice cores 1 the conventional interpretation of ice core deuterium and oxygen 18 isotope profiles based on the use of present day observations spatial slope underestimates glacialinterglacial surface temperature changes in central greenland by up to a factor of two this likely results from changes in the seasonality of the precipitation due to the particular location of the greenland ice sheet next to the highly variable northern polar front in this regard the situation is much simpler for central antarctica and this should be reflected in the temperature interpretation of ice core isotopic records with this in mind we closely examine all relevant information focusing on the east antarctic plateau where both model and empirical isotope temperature estimates are available we point to the fact that correctly accounting for the influence of ocean isotopic change is important when interpreting deuterium profiles from ice cores in this region the evidence presently available indicates that unlike for greenland the present day spatial slope can probably be taken as a surrogate of the temporal slope to interpret glacial interglacial isotopic changes at sites such as vostok and epica dome c corresponding temperature changes are within 10 to 30 of those obtained from the conventional interpretation based on the use of the spatial slope index terms 1040 geochemistry isotopic composition chemistry 1827 hydrology glaciology 1863 3344 meteorology and atmospheric dynamics paleoclimatology 9310 information related to geographic region antarctica keywords water isotopes temperature estimate antarctica deuterium oxygen 18

evidence of displaced terranes from permian to jurassic faunas around the pacific margins for the permian to jurassic time interval tethyan marine invertebrate faunas which are generally accepted as having lived at low latitude can be distinguished from less diverse higher latitude faunas displacement of these low latitude faunas to positions of high latitude around the pacific margins therefore provides key evidence for the movement of so called suspect or displaced terranes the fullest story so far has been worked out for the western margin of n america as far north as southern alaska but there is also convincing evidence for the substantial northward movement of continental segments along the ne asian margin as regards the southern hemisphere the torlesse terrane of new zealand appears to have moved a considerable distance southwards but there is no fauna1 evidence of comparable far travelled suspect terranes along the andean margin of south america not only tethyan and boreal but e and w pacific elements are detectable in the faunas and the distribution of these argues for a panthalassia studded with islands of various sizes fringing the adjacent continents rather than for the disintegration of a single continent pacifica

what are the climate controls on δd in precipitation in the zongo valley bolivia implications for the illimani ice core interpretation abstract controversy has surrounded the interpretation of the water isotopic composition d or 18o in tropical and subtropical ice cores in south america although recent modeling studies using agcm have provided useful constraints at interannual time scales no direct calibration based on modern observations has been achieved in the context of the recent ice core drilling at nevado illimani 16 39 s 67 47 w in bolivia we examine the climatic controls on the modern isotopic composition of precipitation in the zongo valley located on the northeast side of the cordillera real at about 55 km from nevado illimani monthly precipitation samples were collected from september 1999 to august 2004 at various altitudes along this valley first we examine the local and regional controls on the common d signal measured along this valley we show that 1 local temperature has definitely no control on d variations and 2 local rainout is a poor factor to explain d variations we thus seek regional controls upstream the valley potentially affecting air masses distillation based on backtrajectory calculations and using satellite data trmm precipitation noaa olr and direct observations of precipitation iaea gnip we show that moisture transport history and the degree of rainout upstream are more important factors explaining seasonal d variations analysis of a 92 yr simulation from the echam 4 model t30 version implemented with water stable isotopes confirms our observations at seasonal time scale and emphasize the role of air masses distillation upstream as a prominent factor controlling interannual d variations lastly we focus on the isotopic depletion along the valley when air masses are lifted up our results suggest that if the temperature gradient between the base and the top of the andes was higher by a few degrees during the last glacial maximum lgm less than 10 of the glacial to interglacial isotopic variation recorded in the illimani ice core could be accounted for by this temperature change it implies that the rest of the variation would originate from wetter conditions along air masses trajectory during lgm

comparison of atmospheric hydrology over convective continental regions using water vapor isotope measurements from space 1 global measurements of the 500 825 hpa layer mean hdo h2o ratio from the tropospheric emission spectrometer tes are used to expose differences in the dominant hydrologic processes in the amazon north australian and asian monsoon regions the data show high regional isotopic variability and numerous values unexpected from classical rayleigh theory correlation analysis shows that mixing with boundary layer air enhanced isotopic fractionation during precipitation and subsiding air parcels contribute to intraseasonal isotopic variability these local controls explain only 8 30 of total regional variance which suggests that the isotopes are primarily indicators of moist processes that occur upstream seasonal trajectory analysis demonstrates that rayleigh distillation in a lagrangrian framework underestimates the observed isotopic depletion during the monsoons and suggests substantial recycling of water within or below clouds the trajectory results for the dry seasons reveal that subsiding air parcels periodically introduce isotopically depleted air into the north australia and asian monsoon regions whereas vigorous low level convection over the amazon basin acts to quickly enrich and moisten dry subsiding air the analysis indicates variations in the strength of convective detrainment into the lower to middle troposphere over all regions which during the dry seasons of the north australian and asian monsoon regions correlate with increases in relative humidity this study shows that isotopic measurements provide unique diagnostics of mechanisms that control the seasonal sources of water and that these provide a refined understanding of the differences in the characteristics of hydrologic budgets in these monsoonal regions

spatial seasonal patterns reveal large scale atmospheric controls on asian monsoon precipitation water isotope ratios abstract correlated seasonal variation in precipitation amount and its oxygen isotope ratios 18 o has long been observed and frequently invoked in the interpretation of paleo 18 o records from the asian monsoon am region however the underlying cause of the observed seasonal 18 o variation is still under debate precipitation 18 o values show a single consistent seasonal pattern across the region with high values in pre monsoon late spring to early summer and low values in the monsoon mature mid to late summer periods we tested three hypotheses that may give rise to the measured precipitation 18 o pattern involving variation in 1 local precipitation 2 moisture sources and 3 convection in moisture source regions we show that seasonal precipitation amounts across the am region exhibit two pattern types pre monsoon peak or monsoon mature peak and thus do not provide a consistent explanation for the isotopic pattern we test the hypotheses that changing moisture sources or moisture source isotope ratios drive the seasonal isotopic pattern using a combination of lagrangian moisture source attribution and output from an isotope enabled general circulation model lmdz4 but find little seasonal variation in moisture sources that which does exist is not consistent with the observed isotopic change instead we show that the precipitation 18 o transition from pre monsoon to monsoon mature stage is correlated with intensification of convective activity in moisture source regions which is the result of monsoon establishment and northward migration of the intertropical convergence zone itcz we propose that light water vapor transferred to the lower troposphere through downdrafts and evaporation of rain in the vicinity of intense convection is advected to the am region and labels precipitation during the monsoon mature period these results demonstrate that precipitation 18 o in the am region more strongly reflect large scale atmospheric dynamics than local precipitation amount or moisture source guiding the interpretation of paleo isotope data from this region

climate change imprinting on stable isotopic compositions of high elevation meteoric water cloaks past surface elevations of major orogens stable isotope paleoaltimetry has been widely used to estimate cenozoic surface elevation of major orogens the influence of global climate change on stable isotope paleoaltimetry is uncertain with proposals that warming could cause either overestimates or underestimates of past surface elevations in this study we increase atmospheric p co 2 by two and four times in an isotope tracking atmospheric general circulation model to investigate the effect of global warming on oxygen isotopic compositions of precipitation 18 o p over the continents as in other climate models the response in the genesis version 3 model to global warming is an amplification of upper troposphere temperatures through enhanced infrared absorption and a reduction in the surface to upper level temperature gradient due to the temperature dependence of isotopic fractionation vapor 18 o 18 o v follows suit leading to a reduction in the surface to upper troposphere 18 o v gradient in regions of subsidence including the major orogens and deserts downward mixing of 18 o enriched vapor from the troposphere to the near surface further reduces the lapse rate of 18 o v as a consequence of these effects the isotopic composition of precipitation in high elevation regions including the tibetan plateau rocky mountains european alps and andean plateau increases by 3 6 relative to that at low elevations neglect of this climate effect on high elevation 18 o p has likely led to underestimates of the surface elevation of cenozoic orogens