stable isotope paleoaltimetry and the evolution of landscapes and life abstract reconstructing topography of our planet not only advances our knowledge of the geodynamic processes that shape the earth s surface equally important it adds a key element towards understanding long term continental moisture transport atmospheric circulation and the distribution of biomes and biodiversity stable isotope paleoaltimetry exploits systematic decreases in the oxygen 18o or hydrogen d isotopic composition of precipitation along a mountain front when the interaction of topography and advected moist air masses induces orographic precipitation these changes in 18o or d can be recovered from the geologic record and recent geochemical and modeling advances allow a broad range of proxy materials to be evaluated over the last 10 yr stable isotope paleoaltimetry has witnessed rapidly expanding research activities and has produced a broad array of fascinating tectonic and geomorphologic studies many of which have concentrated on determining the elevation history of continental plateau regions these single site studies have greatly expanded what used to be very sparse global paleoaltimetric data the challenge now lies in disentangling the surface uplift component from the impact of climate change on 18o and d in precipitation the robustness of stable isotope paleoaltimetry can be enhanced when high elevation 18o or d data are referenced against low elevation sites that track climate modulated sea level 18o or d of precipitation through time approach analysis of central andean paleosols documents that differences in 18o of soil carbonate between the subandean foreland and the bolivian altiplano are small between 11 and 7 ma but rise rapidly to ca 2 9 after 7 ma corroborating the magnitude of late miocene change in 18o on the altiplano future advances in stable isotope paleoaltimetry will greatly benefit from addressing four key challenges 1 identifying topographically induced changes in atmospheric circulation and associated teleconnections in the global climate system that affect 18o or d of precipitation 2 evaluating on a case by case basis if temporal and spatial changes in isotope lapse rates influence interpretations of paleoelevation 3 interfacing with phylogenetic techniques to evaluate competing hypotheses with respect to the timing of surface uplift and the diversification of lineages 4 characterizing feedbacks between changes in surface elevation and atmospheric circulation as these are likely to be equally important to the diversification of lineages than changes in surface elevation alone tackling these challenges will benefit from the accelerating pace of improved data model comparisons and rapidly evolving geochemical techniques for reconstructing precipitation patterns most importantly stable isotope paleoaltimetry has the potential to develop into a truly interdisciplinary field if innovative tectonic paleoclimatic and evolutionary biology phylogenetic approaches are integrated into a common research framework it therefore opens new avenues to study the long term evolution of landscapes and life

soil n alkane δd and glycerol dialkyl glycerol tetraether gdgt distributions along an altitudinal transect from southwest china evaluating organic molecular proxies for paleoclimate and paleoelevation abstract organic molecular proxies provide a record of the hydrogen isotopic composition of ambient precipitation and paleoenvironmental temperature in terrestrial settings two classes of organic biomarkers are commonly utilized to reconstruct these past environmental conditions straight chained normal alkanes n alkanes and branched glycerol dialkyl glycerol tetraethers brgdgts we measured the dn alkane and the ratio of cyclisation and methylation indexes of branched tetraethers cbt mbt from surface soils along a 1000 km transect along the southeast margin of the tibetan plateau to assess how these proxies record changes in climate parameters that are related to elevation despite variations in ecosystem abundance weighted dnc27 31 data record the d of precipitation across the orogen and indicate minimal change in apparent fractionation en alkane water 133 with elevation n alkane d mirrors the pattern of rayleigh distillation of an air mass undergoing rainout as moisture moves from the bay of bengal into the se margin of the tibetan plateau soil tetraether temperatures provide a reliable measure of modern temperature with an mbt cbt calculated temperature lapse rate 5 8 c km close to the moist adiabat these data reflect ground level conditions that are independent of the shape of the orogen or the source of moisture in combination with a rayleigh distillation model that incorporates temperature and precipitation isotope data paired tetraether temperature and leaf wax isotope data produce a reliable record of changes in environmental conditions associated with modern elevation change across the largest orogen however some tetraether calibrations may impart systematic temperature bias most notably in cold or dry climates these calibration uncertainties can result in underestimates of paleoelevations by up to 1 5 2 km paired isotopic and temperature paleoelevation reconstructions can minimize errors associated with an individual proxy method however we recommend that application of tetraether temperature paleoelevation reconstruction take potential calibration biases into account in paleoelevation estimates

paleoaltimetry potentiality of branched gdgts from southern tibet paleoaltimetric reconstructions of the southern tibetan plateau tp are crucial to understand the processes and mechanisms concomitant with the tectonic collision of the indian and eurasian continental plates we measured the branched glycerol dialkyl glycerol tetraether brgdgt indices from 88 surface soils from the southern tp and found that alkaline soils exhibited lower mbt and mbt cbt derived mat mean annual temperature while mbt cbt derived mat exhibited a strong correlation with altitude r 2 0 84 n 63 for all of the localities with neutral and acidic soils differently we found that mbt5me derived mat exhibited a strong relation with altitude even though a mixture of alkaline samples r 2 0 72 n 83 as a result two regional calibrations were developed including a neutral and acidic soil calibration based on mbt cbt mat and a calibration suitable for both acidic and alkaline soils based on mbt5me mat for the southern tp based on this new soil calibration data set and a recent global soil calibration data set founded on mbt5me we calculated paleo mat of approximate to 9 491 15 to 10 381 47 degrees c at approximate to 15 ma respectively for the namling basin applying these soil calibrations the paleoaltitudes of the namling basin can be calculated to have been between 4 360 41 km above sea level asl and 4 430 36 km asl at approximate to 15 ma respectively similar to the paleoaltitudes of approximate to 4 7 5 4 km asl at approximate to 15 ma inferred from the floral physiognomy of namling basin fossils and stable isotopes these findings would suggest the applicability of mbt cbt and or mbt5me indices as paleotopographic and paleotemperature proxies on the southern tp

stable isotope based paleoaltimetry abstractthe quantitative estimation of paleoaltitude has become an increasing focus of earth scientists because surface elevation provides constraints on the geodynamic mechanisms operating in mountain belts as well as the influence of mountain belt growth on regional and global climate the general observation of decreasing 18o and 2h values in rainfall as elevation increases has been used in both empirical and theoretical approaches to estimate paleoelevation these studies rely on the preservation of ancient surface water compositions in authigenic minerals to reconstruct the elevation at the time the minerals were forming in this review we provide a theory behind the application of stable isotope based approaches to paleoaltimetry we apply this theory to test cases using modern precipitation and surface water isotopic compositions to demonstrate that it generally accords well with observations examples of the application of paleoaltimetry techniques to himalaya tibet and the andes are discussed

a miocene to pleistocene climate and elevation record of the sierra nevada california orographic precipitation of pacific sourced moisture creates a rain shadow across the central part of the sierra nevada california that contrasts with the southern part of the range where seasonal monsoonal precipitation sourced to the south obscures this rain shadow effect orographic rainout systematically lowers the hydrogen isotope composition of precipitation dppt and therefore dppt reflects a measure of the magnitude of the rain shadow hydrogen isotope compositions of volcanic glass dglass hydrated at the earth s surface provide a unique opportunity to track the elevation and precipitation history of the sierra nevada and adjacent basin and range province analysis of 67 well dated volcanic glass samples from widespread volcanic ash fall deposits located from the pacific coast to the basin and range province demonstrates that between 0 6 and 12 1 ma the hydrogen isotope compositions of meteoric water displayed a large 40 decrease from the windward to the leeward side of the central sierra nevada consistent with the existence of a rain shadow of modern magnitude over that time evidence for a miocene to recent rain shadow of constant magnitude and systematic changes in the longitudinal climate and precipitation patterns strongly suggest that the modern first order topographic elements of the sierra nevada characterized the landscape over at least the last 12 million years

biomarker reconstruction of the early eocene paleotopography and paleoclimate of the northern sierra nevada we reconstruct ancient temperature and elevation gradients across the early eocene 52 49 ma northern sierra nevada california united states using organic molecular proxies that record atmospheric and ground level effects of topography paleoelevation was determined by reconstructing the change in the hydrogen isotopic composition of precipitation d precip and mean annual temperature t gdgt glycerol dialkyl glycerol tetraethers from the isotopic composition of fossil angiosperm leaf n alkanes and the distribution of microbially produced soil tetraethers preserved in leaf bearing sediments organic molecular data produce equivalent range scale d n alkane and channel t gdgt paleoelevation estimates that show the northern sierra nevada was a warm 6 8 c warmer than modern high elevation 2 km and moderate to low relief landscape at the eocene climatic optimum modern northern sierra nevada topography likely refl ects post paleocene reduction of mean surface elevation and late cenozoic increases in relief

empirical relationships between elevation and the stable isotope composition of precipitation and surface waters considerations for studies of paleoelevation change a compilation of 68 studies from throughout many of the world s mountain belts reveals an empirically consistent and linear relationship between change in elevation and change in the isotopic composition of precipitation along altitudinal transects the isotopic composition of precipitation decreases linearly with increasing elevation in most regions of the world except in the himalayas and at elevations 5000 m there are no significant differences in isotopic lapse rates from most regions of the world 0 28 permil 100 m except at the extreme latitudes where isotopic lapse rates are higher given information on past changes in the isotopic composition of precipitation preserved in pedogenic or authigenic minerals this global isotopic lapse rate can be used to place numerical constraints on the topo graphic development of some ancient mountain belts or plateaus there are many complicating factors that can confound interpretation of paleoel evation change based on stable isotopes and many of these are unique to specific mountain belts or time periods relevant to all stable isotope based paleoelevation change studies is the temperature dependent isotope fractionation between a pedo genic or authigenic mineral and the water from which it forms in cases where isotopic proxy minerals are sampled from localities where temperature will change simulta neously with elevation change the apparent change in the isotopic composition of precipitation may be dampened by several permil this suggests that samples taken from the rainshadow side of an emerging orographic barrier may be more likely to preserve isotopic changes resulting from mountain uplift than samples taken from atop a rising mountain range or plateau

processes driving deep convection over complex terrain a multi scale analysis of observations from cops iop 9c the convective and orographically induced precipitation study cops analyses the processes driving deep convection over complex terrain convection initiation ci is mainly not only expressed by a single process but by a variety of them which interact on different scales in time and space and finally can lead to deep convection a study of such a case over inhomogeneous terrain is presented in this article data from the cops network of stations are taken to identify the time and location of ci in many cases this is not the same location as the first convective clouds showers or even thunderstorms it is shown that the interaction of the ci processes on multiple scales locally leads to either deep convection and severe storms or calm weather the boundary conditions between the different outcomes are narrow during iop 9c 20 july 2007 a mesoscale convective system mcs embedded in a surface low over eastern france propagated north eastward and a gust front of the mcs reached the cops area during the passage of the gust front through the rhine valley convective activity was significantly reduced the gust front reached the slope of the black forest and the warm and humid air above the mountain range prior to the gust front was lifted up to 2000 m within a short time period within the air prior to the gust front aloft from the surface ci started along a north south oriented line above the crest due to insolation ahead of the gust front a convergence line developed the interaction of local scale orographic winds the regional scale gust front the mesoscale convergence line and the synoptic scale cold front led to a squall line finally individual severe convective cells formed along the outer section of the synoptic scale cold front copyright 2011 royal meteorological society

a novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids we propose a novel tracer for terrestrial organic carbon in sediments based on the analysis of tetraether lipids using high performance liquid chromatography mass spectrometry hplc ms analysis of terrestrial soil and peats shows that branched tetraether lipids are predominant in terrestrial environments in contrast to crenarchaeol the characteristic membrane lipid of non thermophilic crenarchaeota which is especially abundant in the marine and lacustrine environment based on these findings an index was developed the so called branched and isoprenoid tetraether bit index based on the relative abundance of terrestrially derived tetraether lipids versus crenarchaeol this bit index was applied to surface sediments from the angola basin where it was shown to trace the outflow of the congo river furthermore analyses of particulate organic matter from the north sea showed relatively higher bit indices in water column particulate organic matter near large river inputs a survey of globally distributed marine and lacustrine surface sediments shows that the bit index in these environments correlates with the relative fluvial input of terrestrial organic material making this index generally applicable the new proxy allows the rapid assessment of the fluvial input of terrestrial organic material in immature sediments up to 100 ma old

interaction of a warm season frontal system with the coastal mountains of the western united states part ii evolution of a puget sound convergence zone abstract observational analyses and numerical simulations are used to investigate a puget sound convergence zone pscz event that occurred in the lee of the olympic mountains of washington state the pscz which develops when low level airstreams are forced to converge over puget sound by the regional orography is frequently associated with a mesoscale swath of clouds and precipitation across the central puget sound that stretches eastward over the western side of the cascade mountains it was found that latent heat release enhances the pscz circulation and associated precipitation both the olympic and the cascade mountains are important in the formation of the pscz the olympics deflect the low level onshore flow into two branches one along the strait of juan de fuca and another around the southern flank of the olympics in addition a lee trough which develops to the east of this barrier induces convergence over the central puget sound the cascades deflect low level flow over northern puget sound

influence of the wind profile on the initiation of convection in mountainous terrain a number of days with small precipitating convective cells were investigated using weather radars during the cops convective and orographically induced precipitation study field campaign in the region of the vosges and the rhine valley in central europe depending on the weather situation two distinct mechanisms could be identified for the initiation of convection on some days cells were initiated over the ridge of the vosges whereas on other days cells were initiated in the lee of the vosges the initiation of convection appeared to be concentrated in a few favourable locations using the froude number it was possible to describe the two distinct mechanisms when the froude number was low the flow was diverted around the vosges and thermally driven convergence at the ridge initiated convection whereas when the froude number was high the flow passed through mountain gaps and then converged on the lee side with the flow in the rhine valley the convergence on the lee side was enhanced at locations where the outflows through valleys converged low froude numbers were accompanied by weak winds varying with height whereas high froude numbers were observed during situations with stronger southwesterly winds increasing with height

on thermally forced circulations over heated terrain abstracta combination of analytical and numerical models is used to gain insight into the dynamics of thermally forced circulations over diurnally heated terrain solutions are obtained for two layer flows representing the boundary layer and the overlying free troposphere over an isolated mountainlike heat source a scaling based on the linearized boussinesq system of equations is developed to quantify the strength of thermally forced updrafts and to identify three flow regimes each with distinct dynamics and parameter sensitivities this scaling closely matches corresponding numerical simulations in two of these regimes the first characterized by a weakly stable boundary layer and significant background winds and the second by a strongly stable boundary layer in the third regime characterized by weak winds and weak boundary layer stability this scaling is outperformed by a fundamentally different scaling based on thermodynamic heat engines within this regime the inability of wind ventilation or

paleoelevation records from lipid biomarkers application to the tropical andes new results from two novel lipid biomarker based proxies help to constrain the late cenozoic surface elevation history of the eastern cordillera in the tropical northern andes of colombia previous well known studies have suggested rapid latest miocene pliocene 6 3 ma uplift on the basis of an abrupt shift in pollen species assemblages within sedimentary basin fill of the elevated bogota plateau from resampling of these original study localities we provide a revised chronology based on magnetic polarity stratigraphy and we evaluate paleotemperatures using the mbt cbt indices methylation of branched tetraethers cyclization of branched tetraethers and hydrogen isotopic composition d of leaf waxes as two independent proxies of past surface elevation reconstructed paleotemperatures from the mbt cbt proxy show a more gradual cooling trend from ca 7 6 ma to present consistent with less than 1000 m of elevation gain since latest miocene pliocene time and in agreement with geologic evidence for accelerated shortening and exhumation at this time the leaf wax isotopic data on the other hand lack a systematic trend potentially due to fractionation changes associated with uplift induced turnover in floral populations such changes could obscure isotopic variations in meteoric water suggesting that leaf wax isotopic compositions may not provide a direct proxy for elevation in this particular situation involving uplift in a heterogeneous tropical environment more promising in this case is the mbt cbt proxy which may offer a suitable alternative to carbonate based paleoelevation proxies in tropical regions where year round high precipitation rates prevent formation of soil carbonates

a mesoscale data analysis and downscaling method over complex terrain abstract a mesoscale data analysis method for meteorological station reports is presented irregularly distributed measured values are combined with measurement independent a priori information about the modification of analysis fields due to topographic forcing as a physical constraint to a thin plate spline interpolation the so called fingerprint method recognizes patterns of topographic impact in the data and allows for the transfer of information to data sparse areas the results of the method are small scale interpolation fields on a regular grid including topographically induced patterns that are not resolved by the station network presently the fingerprint method is designed for the analysis of scalar meteorological variables like reduced pressure or air temperature the principles for the fingerprint technique are based on idealized influence fields they are calculated for thermal and dynamic surface forcing for the former the effects of reduced air volumes in valleys the elevated heat s

observation of convection initiation processes with a suite of state of the art research instruments during cops iop 8b in the afternoon of 15 july 2007 a thunderstorm was initiated within a line of cumulus clouds which formed parallel to the crest of the black forest mountains during the intensive observation period iop 8b of the convective and orographically induced precipitation study cops this paper extends the analysis of processes that led to convection initiation ci i e the transition from shallow to deep convection on this day with the data from several cops instruments that have not been considered in previous studies in particular the boundary layer structure lids and the water vapour field in the pre convective environment of the event are discussed for this purpose we investigated measurements of water vapour lidars temperature lidars and wind lidars profiles from radiosondes in situ aircraft data and gridded data of weather stations as well as gps integrated water vapour data and satellite imagery thermally driven circulation systems formed over both the black forest and the vosges mountain ranges which resulted in local convergence zones these superimposed with the large scale convergence in the black forest area in the presence of sufficient moisture and updraught clouds formed close to the mountain crests the related latent heat release allowed larger thermals to be produced which may have had a positive feedback on stabilizing these convergence zones as a whole we believe that differences in the moisture field explain why convection remained shallow and sparse over the vosges mountains because these differences were responsible for differences in convective inhibition cin the stationary location of the convergence zone over the southern black forest was probably decisive for ci because it constantly transported sensible and latent heat into the area in which ci took place

can stable isotopes ride out the storms the role of convection for water isotopes in models records and paleoaltimetry studies in the central andes abstract globally changes in stable isotope ratios of oxygen and hydrogen o 18 and d in the meteoric water cycle result from distillation and evaporation processes isotope fractionation occurs when air masses rise in elevation cool and reduce their water vapor holding capacity with decreasing temperature as such o 18 and d values from a variety of sedimentary archives are often used to reconstruct changes in continental paleohydrology as well as paleoaltimetry of mountain ranges based on 234 stream water samples we demonstrate that areas experiencing deep convective storms in the eastern south central andes 22 28 s do not show the commonly observed relationship between o 18 and d with elevation these convective storms arise from intermontane basins where diurnal heating forces warm air masses upward resulting in cloudbursts and raindrop evaporation especially at the boundary between the tropical and extra tropical atmospheric circulation regimes where deep convective storms are very common 26 to 32 n and s the impact of such storms may yield non systematic stable isotope elevation relationships as convection dominates over adiabatic lifting of air masses because convective storms can reduce or mask the depletion of heavy isotopes in precipitation as a function of elevation linking modern or past topography to patterns of stable isotope proxy records can be compromised in mountainous regions and atmospheric circulation models attempting to predict stable isotope patterns must have sufficiently high spatial resolution to capture the fractionation dynamics of convective cells

evaluation of leaf wax δd and soil brgdgts as tools for paleoaltimetry on the southeastern tibetan plateau abstract the orogenic history of the tibetan plateau tp and surrounding mountain ranges continues to be a major source of disagreement among geologists particularly concerning the uplift models for the cenozoic evolution of the tp and estimates for when the highest and largest plateau on earth reached its current elevation quantitative reconstructions of past elevation from geologic samples are necessary to document the uplift history of tp and examine the interactions between tectonic relief and climate over geological time scales several studies establishing lipid biomarker based paleoaltimetry based on leaf wax d values and brgdgts have been reported in recent years for the tp and surrounding regions but have yet to be synthesized into a regional framework for paleoelevation determination and uncertainty analysis here we report new leaf wax d and brgdgts data developed from surface soil samples along an elevation transect spanning 1250 3900 m a s l in the hengduan mountains on the southeastern edge of the tp we find that the abundance weighted mean leaf wax d n c27 n c29 and n c31 values dwax lapse rates determined for the hengduan mountains and for five other nearby study locations are statistically indistinguishable and can be combined to provide a regional dwax lapse rate of 1 97 0 04 1 100 m for use in regional paleoelevation studies across the southeastern tp we also find a strong correlation r2 0 71 between brgdgts and elevation dependent mean annual air temperature which contributes to a number of studies in the region that support the use of fossil brgdgts as a paleoelevation proxy our results reveal that dwax and brgdgts for the hengduan mountains provide similar empirical uncertainty in paleoelevation reconstruction with standard errors of elevation estimation se of 483 m 1 and 394 m 1 respectively we propose a paleoaltimetric approach that combines dwax and brgdgt data in order to derive paleoelevation estimates with lower uncertainties in the hengduan mountains data set the approach yields a se 286 m 1 that is 27 40 lower than when dwax values and brgdgts are applied separately

altitudinal shift in stable hydrogen isotopes and microbial tetraether distribution in soils from the southern alps nz implications for paleoclimatology and paleoaltimetry abstract the southern alps are an ideal locality for studying patterns of isotopic fractionation associated with orographic precipitation we have evaluated whether altitudinal change is reflected in the stable hydrogen isotopic composition 2 h of stream water plant stem water and leaf wax lipids n alkanes from living plants and soils as well as in soil temperature samples were collected along an altitudinal transect from the windward side of the southern alps to lake hawea in the rain shadow the results indicate that 2 h values of stem water overlap with stream water demonstrating a gradual decrease with elevation that complied with modeled rayleigh distillation reflecting an isotopic lapse rate of 18 0 1 1 1 km leaf and soil n alkanes shared similar 2 h values and were 2 h depleted relative to stem stream waters the values for soil n alkanes indicated an isotopic lapse rate of 21 8 2 0 1 km consistent with precipitation data and long term observations mbt cbt derived soil temperature values based on the relative distribution of microbial tetraether lipids were similar to midsummer temperature observations displaying an elevational decrease rate of 5 6 1 5 1 c km consistent with regional and global observations the results indicate that sedimentary lipid 2 h and microbial tetraether temperature estimates captured altitudinal trends in the isotopic composition of precipitation and mean temperature and further support their application in the reconstruction of past climate and surface uplift histories however notable differences in isotopic composition and temperature estimates between in situ soils and those with downslope transport of material emphasize the importance of facies analysis when interpreting past systems

topographic development of the southern alps recorded by the isotopic composition of authigenic clay minerals south island new zealand abstract the southern alps are developing as a consequence of oblique collision between the pacific and australian plates the southern alps lie on the west side of the south island of new zealand and create a massive rain shadow where greater than 12 m year of rain falls on the west coast and semiarid conditions exist to the east the rain out effect across the mountains causes precipitation west of the southern alps to have d and 18 o values averaging 30 and 5 5 whereas precipitation in the rain shadow to the east is isotopically lighter d 72 and 18 o 9 8 such large differences in the isotopic composition of precipitation would not have existed prior to the development of significant topography we have examined the topographic evolution of the southern alps using oxygen isotope analyses of authigenic kaolinites formed in the rain shadow to the east of the mountains between the cretaceous low topography and the pleistocene changes in the isotopic composition of authigenic clay minerals forming in equilibrium with meteoric water in the stratigraphic sequence record the development of southern alps topography and the resultant rain shadow our oxygen isotope analyses of authigenic kaolinites show a 5 6 decrease in the early pliocene from 18 2 in older rocks to 12 3 in younger rocks in addition smectite is abundant in all samples from the late miocene to recent but is conspicuously absent in most older rocks suggesting a change to a generally drier climate roughly coincident with the isotopic shift in kaolinites this method may be useful in unraveling timing of development of mountain belts elsewhere in the world

altitudinal climatic index changes in subtropical china indicated from branched glycerol dialkyl glycerol tetraethers proxies abstract branched glycerol dialkyl glycerol tetraethers brgdgts have been widely applied in climate parameter reconstructions over the past few years mbt 5me the methylation of branched tetraethers based on the 5 methyl isomers and cbt cyclisation of branched tetraethers that includes 6 methyl brgdgts in the numerator have proven to be useful brgdgt proxies for interpreting the mean annual air temperature mat and soil ph of different climate condition areas in china however the application of mbt 5me and cbt for indicating altitudinal climate conditions is still open to discussion e g the lack of comparisons between attitudinal results from mountain areas of different climate conditions in this study we compared soil brgdgt along three mountain transects in subtropical china i e mt gaoligong mt fanjing and mt shennongjia the brgdgt distributions of mt gaoligong and mt fanjing were similar to the subtropical surface soil brgdgt distribution pattern featured by the dominance of chemical structures of brgdgts ia and iia however mt shennongjia was characterised by increasing brgdgts iiia iia iib and ib much like the semi humid humid temperate climate area brgdgt distribution pattern these results indicate that altitudinal climate indicators such as temperature and precipitation could be recorded by varied brgdgt distributions also mbt 5me inferred mats were negatively correlated with mountain altitude r2 0 79 0 87 the mat lapse rate increased from mt shennongjia to mt fanjing to mt gaoligong 0 5 c 100 m 0 9 c 100 m and 1 3 c 100 m respectively the influence of the qinghai tibetan plateau ice cover and differences in latitudinal temperature and or moisture conditions might be the reasons for the various lapse rates the soil ph was less correlated with altitude r2 0 58 0 63 than to the regression of mat and altitude showing slightly different relations from those of horizontal studies at mt gaoligong and mt fanjing soil ph and altitude demonstrated positive linear regressions but with different slopes the different reducing rate of soil ph as a function of altitude for the two mountains is probably caused by their dominating summer monsoons for mt shennongjia where the climate condition is less humid than mt gaoligong and mt fanjing the soil ph did not significantly change with altitude and thus no relationship was observed this might probably be partially induced by the weakly alkaline parent rocks of mt shennongjia

hydrogen isotope ratios of terrestrial leaf wax n alkanes from the tibetan plateau controls on apparent enrichment factors effect of vapor sources and implication for altimetry abstract empirical evidence suggested that the altitudinal dependence of hydrogen isotope ratios of leaf wax n alkanes d wax can be used to estimate paleoaltitudinal changes however the application of d wax based paleoaltimetry remains difficult as the impacts of evaporative transpirative and biosynthetic processes on hydrogen isotope fractionations in changing environments and the influence of likely changing water vapor sources are not well explored for this study we sampled stream waters soils and plant leaves along two transects spanning large gradients of altitude precipitation amount vapor source temperature and vegetation type on the tibetan plateau tp d values of stream water as an approximation for d p soil water d sw and plant leaf water d lw as well as leaf wax n alkanes were measured in order to quantify isotopic fractionations in the formation of leaf waxes most interestingly we found a strong negative correlation between the evapotranspirative enrichment of leaf water against precipitation e lw p which combines the effects of soil evaporation and leaf transpiration and the biosynthetic hydrogen isotope fractionation e wax lw which describes isotopic enrichment between leaf wax and leaf water the relationship yields a steady apparent isotopic enrichment factor e wax p between leaf wax and precipitation which is independent from climatic parameters and has an average value of 107 26 for grasses monocotyledons and 77 22 for trees dicotyledons since the terrestrial n alkanes especially n c 27 and n c 29 in sediments are derived from trees and grasses the likely change of the vegetation type in the uplift of mountains can change the isotopic estimates by about 30 which corresponds to an altitudinal change of 1600 m we therefore suggest that hydrogen isotope ratio of sedimentary n c 31 alkane which is mainly derived from grasses might be better proxies to reconstruct paleoaltitudes our large dataset of d wax from trees and grasses that aimed to mirror the variability of environmental factors over geological time frames showed the lapse rates were significant but much smaller than in previous studies most importantly our result demonstrated that the lapse rate significantly differed for both transects p 0 0068 i e 0 87 0 71 100 m r 2 0 28 p 0 2841 n 6 and 2 28 0 82 100 m r 2 0 34 p 0 0135 n 17 for indian monsoon and westerly dominated areas respectively this suggests that different moisture sources might strongly affected the observed lapse rates in consequences altitude reconstructions are strongly complicated in areas with likely changing air masses like the tibetan plateau

leaf wax stable isotopes from northern tibetan plateau implications for uplift and climate since 15 ma abstract the growth of tibetan plateau is considered to have played a key role during the evolution of asian climate our understanding of the relationship between the plateau growth and asian climate changes is limited however due to the scarcity of well dated sedimentary sequences that could provide parallel information of the evolution of elevation and climate here we report a high resolution time series record of the stable hydrogen isotopic composition of leaf wax n alkanes d n alk from a continuous neogene stratigraphic sequence 15 1 8 ma from the qaidam basin on the northern tibetan plateau these data are used to reconstruct the isotopic composition of meteoric waters d m and subsequently applied to interpret the history of paleotopography and climate in qaidam our results indicate four stages in the evolution of hydrology in the qaidam basin in stage i 15 ma to 10 4 ma d m gradually decreases from 24 9 to 75 5 synchronous with a period of active tectonism the estimated topographic growth of 2 1 0 3 km is comparable to the height of qaidam basin relative to the foreland hexi corridor we note that c 3 plants were dominant in this region since the miocene we take this as independent evidence that this area was mountainous before the c 4 expansion in late miocene and pliocene d m variability in subsequent stages appears to be related to shifts in dry and moist conditions and independent of topographical changes a conclusion supported by other independent climatic records on the tibetan plateau high d m values in stage ii 10 4 ma to 6 9 ma are related to severe aridity and stage iii 6 9 ma to 4 1 ma is marked by low d m values suggestive of moist conditions related to the strengthening east asia summer monsoon high d m values in stage iv 4 1 ma to 1 8 ma reflect a climate drier than the present

initiation of convection over the black forest mountains during cops iop15a doppler on wheels radar observations made during the convective and orographically induced precipitation study cops on 12 august 2007 showed that precipitating clouds only developed between the north south orientated murg and nagold valleys of the northern black forest the clouds produced moderate precipitation the weather research and forecasting wrf model run at 700 m horizontal resolution in the inner domain was able to simulate the location of the precipitation insight is therefore gained into the physical mechanisms responsible for the initiation and development of the convection convergence lines resulting from thermally driven flows constrained the initial location of the convection within warm and moist cores produced by heating on elevated surfaces the heaviest precipitation was later produced by secondary convection which was initiated within the cores at the boundary between cold pool outflows and thermal flows copyright 2011 royal meteorological society

onset of convective rainfall during gradual late miocene rise of the central andes a decrease in the ratio of 18o to 16o 18o of sedimentary carbonate from the bolivian altiplano has been interpreted to indicate rapid surface uplift of the late miocene andean plateau ap here we report on paleoclimate simulations of andean surface uplift with an atmospheric general circulation model gcm that tracks oxygen isotopes in vapor the gcm predicts changes in atmospheric circulation and rainfall that influence ap isotopic source and amount effects on eastern ap slopes summer convective precipitation increases by up to 6 millimeters per day 500 for plateau elevations that are greater than about 2000 meters high precipitation rates enhance the isotope amount effect leading to a decrease in precipitation 18o at high elevations and an increase in 18o lapse rate our results indicate that late miocene 18o depletion reflects initiation and intensification of convective rainfall

a new approach to stable isotope based paleoaltimetry implications for paleoaltimetry and paleohypsometry of the high himalaya since the late miocene the change in oxygen isotopic composition of precipitation is modeled using equilibrium fractionation during rayleigh distillation linked to the thermodynamics of atmospheric ascent and water vapor condensation the primary controllers of the vertical variation in isotopic composition with elevation are the low elevation temperature and relative humidity as these control the vertical distribution of condensation an empirical fit of precipitation versus model condensation based on alpine stations is derived this fit is represented in the model as the weighted mean composition of condensation within a 1000 m thick air parcel 1500 500 m above the ground surface and is used for all other regions comparison of model versus observed modern precipitation reveals a close fit particularly of more highly elevated sites comparison of modern waters in the himalayas and southern tibet with model predictions particularly as revealed by comparison of observed and predicted hypsometry provides additional support to the validity of the model finally application of this model to estimates of paleo waters in the himalayas and southern tibet reveals that this region had already achieved its present hypsometry by the late miocene about 10 ma ago fl 2001 published by elsevier science b v

predicting paleoelevation of tibet and the himalaya from δ18o vs altitude gradients in meteoric water across the nepal himalaya the 18o value of meteoric water varies with elevation providing a means to reconstruct paleoelevation if the 18o values of paleowater are known in this study we determined the 18o values of water 18omw from small tributaries along the seti river and kali gandaki in the nepal himalaya we found that 18omw values decrease with increasing altitude for both transects 18omw vs altitude along the kali gandaki in west central nepal fit a second order polynomial curve consistent with increasing depletion of 18o with increasing elevation as predicted by a rayleigh type fractionation process this modern 18omw vs altitude relationship can be used to constrain paleoelevation from the 18o values of miocene pliocene carbonate 18oc deposited in the thakkhola graben in the southern tibetan plateau paleoelevations of 3800 480 m to 5900 350 are predicted for the older tetang formation and 4500 430 m to 6300 330 m for the younger thakkhola formation these paleoelevation estimates suggest that by 11 ma the southern tibetan plateau was at a similar elevation to modern

early holocene thermal maximum recorded by branched tetraethers and pollen in western europe massif central france abstract the evolution of temperatures during the holocene is controversial especially for the early holocene the occurrence of the holocene thermal maximum htm during the early holocene has recently been reconsidered and seasonal biases have been suggested in the paleoclimatic proxies high regional variability and a low number of reliable and continuous quantitative reconstructions compared with the oceanic realm further complicate study of the holocene climate in the continental realm we analyzed branched glycerol dialkyl glycerol tetraethers brgdgts an organic paleothermometer and palynological signals as part of a multiproxy analysis of the sedimentary record from lake st front in the massif central france identification of a shift in brgdgt sources through the holocene required removing terrigenous influences from the temperature signal brgdgt and pollen inferred paleotemperature reconstructions based on the modern analog technique and the weighted averaging partial least squares method were compared both showed a thermal maximum during the early holocene followed by a decrease of temperatures we evaluated biases which could potentially influence the reconstructed signal there was no evidence for a summer temperature bias either for brgdgt derived temperatures or for pollen derived temperatures the lake st front data in agreement with other regional records confirm the occurrence of the htm as a general warm period during the early holocene followed by mid holocene cooling in western europe and suggest that seasonal biases are not the main explanation of the holocene conundrum the disagreement between model simulations and proxy based temperature reconstructions for the northern hemisphere

a 15 year hail streak climatology for the alpine region in this study we present a unique 15 year hail streak climatology for switzerland based on volumetric radar reflectivity two radar based hail detection products and an automatic thunderstorm tracking algorithm were reprocessed for the extended convective season april september between 2002 and 2016 more than 1 1 million convective cells were automatically tracked over the full radar domain and over 191 000 storms and 31 000 hail streaks in the considered subdomain were selected for analysis following consistency and robustness tests the year to year variability in t h e number of hailstorms reveals two types of convective seasons a a few seasons with hail frequency far above the average and b all other years with an average number of hailstorms a high number of hailstorms in a particular year is not correlated with a higher number of convective storms in general but is related to a greater fraction of severe storms convection initiation hail initiation and hail frequency maxima are located along the southern and northern foothills over the pre alpine area and over th e jura mountains few hail streaks are present over the alpine main ridge hail streak frequency and location is found to be strongly dependent on the synoptic scale weather regimes this is important for monthly and seasonal outlooks as well as for climate modelling analysis of storm life cycles shows that a the majority of hail swaths contain only a single hail streak b severe storms follow a more rapid evolution during their initial stages than do less severe storms and c severe storms produce more spatially extended hail streaks finally significant seasonal and diurnal cycles are present in most of the considered storm characteristics

late miocene climate variability and surface elevation in the central andes abstract temporal and spatial variations in topography and oxygen stable isotope ratios in precipitation in the central andes have stimulated widespread discussion about the competing roles of mantle and crustal processes and their feedbacks with global scale climatic change in uplifting and shaping the central andes in general one of the major obstacles in assessing the relative contributions of long term 10 5 10 6 a tectonic processes and precipitation as a proxy for climate to the uplift history of the andean orogen is the lack of integrated data sets that record late miocene patterns of uplift and climate radiogenic 87 sr 86 sr sedimentologic and stable isotope 18 o data from subandean foreland deposits of the chaco basin bolivia show a rapid 18 o and 87 sr 86 sr values at 8 5 ma that we interpret to reflect a change in precipitation patterns along the eastern cordillera and the subandean fold thrust belt in agreement with 13 c studies on paleosol carbonates we attribute this change to a southward deflection of the south american low level jet llj that currently exerts the dominant control over the seasonality and amount of precipitation along the eastern flanks of the andes deflection of the llj occurred most likely as the combined effects of readjustment of relief and topography within the eastern cordillera at 20 22 s and possibly associated surface uplift of the altiplano contemporaneous rapid positive shifts in 18 o and 87 sr 86 sr of pedogenic carbonate in fluvial foreland deposits are consistent with a transition to more seasonal precipitation conditions and critical threshold elevations being attained that affected south american atmospheric circulation patterns a four fold increase in sedimentation rates in the foreland together with a shift to strongly radiogenic 87 sr 86 sr ratios in paleo river water and sediment load as well as river incision into the well preserved san juan del oro paleo surface directly reflects a rapid change in moisture distribution along the eastern flank of the central andes at 8 5 ma and associated rearrangement of the drainage systems collectively the data presented here strongly suggest that between 12 and 8 ma the amount oxygen isotopic composition spatial distribution and seasonality of precipitation along the eastern flank of the bolivian andes changed dramatically which in turn require changes in trans andean moisture flux and isotopic composition of precipitation on the uplifting plateau region

sources of local and regional variability in the mbt cbt paleotemperature proxy insights from a modern elevation transect across the eastern cordillera of colombia abstract distributions of brgdgts branched glycerol dialkyl glycerol tetraethers in soils have been utilized in the literature as a proxy for temperature and ph via the mbt and cbt indices methylation of branched tetraethers and cyclization of branched tetraethers respectively however there is substantial scatter in the empirical relationships between the global mbt cbt index and modern temperature resulting in uncertainty as large as 5 0 c in reconstructed paleotemperature in this study we sought to determine the magnitude of several sources of calibration error using a new set of samples spanning a large gradient in elevation ca 3000 m and temperature ca 16 c across an andean transect in the eastern cordillera of colombia using in situ temperature monitoring this field study of an equatorial montane location provided an opportunity to investigate several potential confounding factors affecting the mbt cbt paleothermometer including the mismatch between air temperature and actual soil temperature and the effect of soil moisture on brgdgt production in the well constrained environment of our study we determined the rmse root mean squared error for a local calibration of the mbt cbt proxy to be 3 0 c in contrast to the 5 0 c value reported in the most recent global calibration a comparison between in situ soil temperature measurements at our soil sampling locations and interpolated weather station temperature data indicates that errors in interpolation schemes are not likely to be a significant contributor to the observed scatter in the mbt cbt temperature relationship rather we conclude that the majority of the 3 c scatter in this calibration for the northern andes arises from transient site specific variation in factors such as soil moisture and nutrient availability with several cases showing a difference of up to 7 8 c between closely spaced sites

paleoaltimetry of the tibetan plateau from d h ratios of lipid biomarkers abstract the past elevation of the land surface provides a unique constraint on the underlying lithospheric structure during mountain and plateau formation development of new paleoaltimetry techniques that can be applied to a wide variety of sample types is therefore of continuing importance this study evaluates organic substrates that preserve the d ratio of surface waters as a new approach to reconstruct paleoaltimetry we measured the hydrogen isotope composition of n alkanes from epicuticular plant waxes preserved in lacustrine deposits to reconstruct the d of precipitation in cenozoic basins that have been elevated as part of the tibetan plateau n alkane d and carbonate 18 o inferred water compositions from the eocene miocene lunpola basin and miocene hoh xil basin plot near or at enriched values relative to the global meteoric water line as expected for evaporative lakewater and leafwater systems that have the same precipitation source n alkane d based water compositions are nearly identical to the minimum carbonate 18 o based values demonstrating that plant wax d is minimally affected by evaporation compared to lacustrine calcite 18 o this agreement strongly supports the presence of similar precipitation isotopic compositions in both archives despite different isotope systems source water reservoirs archive materials modes of incorporation and diagenetic processes paleoelevations for each basin and time period were calculated from precipitation isotope ratios using the isotope altitude relationship derived from both a simple thermodynamic model and modern precipitation sampling from the plateau region our new results from the hoh xil basin suggest 1700 to 2600 m of uplift may have occurred some time between the late eocene and early miocene the timing of this uplift is consistent with late oligocene compressional deformation of the hoh xil basin and northward growth of the tibetan plateau however the calculated uplift is not a unique solution from the paleoisotope data because of uncertainties in eocene and miocene moisture sources and isotope gradients for the northern plateau our results demonstrate the utility of lipid based estimates of paleoelevation and expand the types of deposits amenable to paleoaltimetry analysis

mountain volume control on deep convective rain amount during episodes of weak synoptic forcing abstractthermally driven upslope flows in mountainous areas provide favorable conditions for diurnal deep moist convection especially during episodes of weak synoptic forcing the present study inv

leaf wax biomarkers in transit record river catchment composition rivers carry organic molecules derived from terrestrial vegetation to sedimentary deposits in lakes and oceans storing information about past climate and erosion as well as representing a component of the carbon cycle it is anticipated that sourcing of organic matter may not be uniform across catchments with substantial environmental variability in topography vegetation zones and climate here we analyze plant leaf wax biomarkers in transit in the madre de dios river peru which drains a forested catchment across 4 5 km of elevation from the tropical montane forests of the andes down into the rainforests of amazonia we find that the hydrogen isotopic composition of leaf wax molecules specifically the c28 n alkanoic acid carried by this tropical mountain river largely records the elevation gradient defined by the isotopic composition of precipitation and this supports the general interpretation of these biomarkers as proxy recorders of catchment conditions however we also find that leaf wax isotopic composition varies with river flow regime over storm and seasonal timescales which could in some cases be quantitatively significant relative to changes in the isotopic composition of precipitation in the past our results inform on the sourcing and transport of material by a major tributary of the amazon river and contribute to the spatial interpretation of sedimentary records of past climate using the leaf wax proxy

rise of the andes the surface uplift of mountain belts is generally assumed to reflect progressive shortening and crustal thickening leading to their gradual rise recent studies of the andes indicate that their elevation remained relatively stable for long periods tens of millions of years separated by rapid 1 to 4 million years changes of 1 5 kilometers or more periodic punctuated surface uplift of mountain belts probably reflects the rapid removal of unstable dense lower lithosphere after long term thickening of the crust and lithospheric mantle

an observational and modeling study of the processes leading to deep moist convection in complex terrain abstracta case study of orographic convection initiation ci that occurred along the eastern slopes of the vosges mountains in france on 6 august 2007 during the convective and orographically induced precipitation study cops is presented global positioning system gps receivers and two doppler on wheels dow mobile radars sampled the preconvective and storm environments and were respectively used to retrieve three dimensional tomographic water vapor and wind fields these retrieved data were supplemented with temperature moisture and winds from radiosondes from a site in the eastern rhine valley high resolution numerical simulations with the weather research and forecasting wrf model were used to further investigate the physical processes leading to convective precipitation this unique time varying combination of derived water vapor and winds from observations illustrated an increase in low level moisture and convergence between upslope easterlies and downslope westerlies along the eastern slo

boundary layer updrafts driven by airflow over heated terrain abstractthis study presents linear and nonlinear scalings for boundary layer ascent forced by airflow over heated terrain and compares them to results from corresponding high resolution numerical simulations close agreement between theory and simulation is found over most of the parameter space considered including variations in background winds boundary layer stability mountain height and diabatic heating rate as expected the linear and nonlinear scalings perform best for linear and nonlinear flows respectively for a convective boundary layer the scalings accurately predict vertical motion for all flows considered including those that extend well into the nonlinear regime thus these scalings may ultimately help to improve the parameterization of subgrid orographic ascent in large scale models the vertical velocity scalings are less accurate for mechanically blocked flows in stable boundary layers for which a simple vertical displacement scaling is superior although the scalings do not tre

orographic barriers high resolution trmm rainfall and relief variations along the eastern andes 1 quantifying the degree to which tectonic and erosive processes shape landscapes is key to understanding the evolution of tectonically active mountain belts here we explore the interplay of these two processes along the humid eastern flank of the south american andes we use high resolution tropical rainfall measurement mission trmm and srtm data to characterize elevation relief and hillslope angle of peak rainfall at orographic barriers over a distance of more than 3500 km along the eastern flanks we find that peak rainfall 3 5 m yr occurs at a mean elevation of 1 3 0 17 km a mean relief of 0 95 0 08 km and at moderate mean hillslope angles of 18 3 1 7 we suggest that topographic relief is the best first order rainfall predictor and we demonstrate how relief changes along strike south of the andean orocline alter rainfall distribution changes in climatic sedimentary and tectonic processes prevent the formation of high relief amounts at the mountain front and these areas are not characterized by pronounced rainfall peak

distribution of glycerol dialkyl glycerol tetraethers in soils from two environmental transects in the usa abstract glycerol dialkyl glycerol tetraethers gdgts of both archaeal and bacterial origin form the basis of new temperature proxies applicable to soil and lake and marine sediments in soil branched gdgts are prevalent and their abundance of methyl or cyclic groups has been calibrated to mean annual temperature mat using mbt and cbt indices however soil ph is also known to be an important variable controlling the distribution of branched gdgts precipitation amount helps control soil moisture as well as ph and soil moisture is a leading variable affecting microbial diversity and activity in soil we have evaluated the distribution of gdgts from two soil transects in the usa a dry western transect covering six western states and a wet east coast transect from maine to georgia in order to assess the effect of precipitation on the distribution of soil gdgts our results show distinctly different gdgt distributions across climatic regions with dry western soils characterized predominantly by thaumarchaeotal isoprenoid iso gdgts and as a consequence low bit index values 0 2 0 6 and moist temperate east coast transect soils expressing mostly branched br gdgts and higher bit values 0 9 1 the predominance of iso gdgts in the western soils is related to the degree of aeration which in turn is related to precipitation amount and also to soil ph we also observed a substantial increase in the offset between measured mat and mbt cbt based mat below an annual precipitation of 700 800 mm yr 1 implying an impact of precipitation amount on mbt cbt based temperature reconstruction the data suggest that while soil tetraethers work well as a temperature proxy in moist temperate regimes they do not produce reliable measurements of temperature in sediments sourced from areas with 1 precipitation moreover erosion of soils with low bit values into lacustrine or marginal marine environments will not be detected via the bit index which can potentially affect paleotemperature reconstruction from sediments and so provide erroneous estimates of soil carbon delivery bit index values also show a correlation with precipitation amount the abundance of iso gdgts in western transect soils allowed calculation of tex 86 values but no correlation was found between tex 86 calculated temperature and mean annual temperature

airborne radar stratigraphy and electrical structure of temperate firn bagley ice field alaska u s a helicopter borne 135 mhz short pulse radar profiles of the bagley ice field southern alaska u s a have been analyzed to determine the nature of radio wave propagation through crevassed stratified wet and draining firn diffractions characterize the firn horizons along the trunk and reflections characterize those of overlying snow fields dynamic stacking was used to form and determine firn depths and unstacked diffraction analysis to determine firn layer properties refractive indices range from 4 1 to 4 5 for the near surface from 1 7 to 2 1 at about 13 17 m depth along the main trunk and to 2 6 to 58 m depth within a snowfield average trunk values correspond with volumetric water contents of about 0 09 which agree with values measured for other glaciers the analysis of the airborne recorded diffractions is confirmed by deriving the approximate refractive index of water from a supraglacial lake bottom diffraction the lack of snowfield diffractions suggests that crevassing and not firn structure caused the trunk diffractions the reasonable values of the indices imply that the diffractions originated from single points or edges orthogonal to the profile transect and they predict low interlayer transmission losses the snowfield penetration suggests that several hundred meters might be penetrated in uncrevassed accumulation zones with improved system design

on the origin of the bolivian high and related circulation features of the south american climate abstract the climatological structure in the upper tropospheric summertime circulation over south america is diagnosed using a gcm with and without south american topography a linear model and observational data emphasis is placed on understanding the origin of observed features such as the bolivian high and the accompanying nordeste low to the east results from the linear model indicate that these two features are generated in response to precipitation over the amazon basin central andes and south atlantic convergence zone with african precipitation also playing a crucial role in the formation of the nordeste low the direct mechanical and sensible heating effects of the andes are minimal acting only to induce a weak lee trough in midlatitudes and a shallow monsoonal circulation over the central andes in the gcm the effects of the andes include a strengthening of the bolivian high and northward shift of the nordeste low primarily through changes in the precipitation field the position of

elevation dependent changes in n alkane δd and soil gdgts across the south central andes abstract surface uplift of large plateaus may significantly influence regional climate and more specifically precipitation patterns and temperature sometimes complicating paleoaltimetry interpretations thus understanding the topographic evolution of tectonically active mountain belts benefits from continued development of reliable proxies to reduce uncertainties in paleoaltimetry reconstructions lipid biomarker based proxies provide a novel approach to stable isotope paleoaltimetry and complement authigenic or pedogenic mineral proxy materials in particular outside semi arid climate zones where soil carbonates are not abundant but soil organic matter has a high preservation potential here we present d values of soil derived n alkanes and mean annual air temperature mat estimates based on branched glycerol dialkyl glycerol tetraether brgdgt distributions to assess their potential for paleoelevation reconstructions in the southern central andes we analyzed soil samples across two environmental and hydrological gradients that include a hillslope 26 28 s and a valley 22 24 s transect on the windward flanks of central andean eastern cordillera in nw argentina our results show that present day n alkane d values and brgdgt based mat estimates are both linearly related with elevation and in good agreement with present day climate conditions soil n alkanes show a d lapse rate d of 1 64 100 m r 2 0 91 p 0 01 at the hillslope transect within the range of d lapse rates from precipitation and surface waters in other tropical regions in the andes like the eastern cordillera in colombia and bolivia and the equatorial and peruvian andes brgdgt derived soil temperatures are similar to monitored winter temperatures in the region and show a lapse rate of t 0 51 c 100 m r 2 0 91 p 0 01 comparable with lapse rates from in situ soil temperature measurements satellite derived land surface temperatures at this transect and weather stations from the eastern cordillera at similar latitude as a result of an increasing leeward sampling position along the valley transect lapse rates are biased towards lower values and display higher scatter d 0 95 100 m r 2 0 76 p 0 01 and t 0 19 c 100 m r 2 0 48 p 0 05 despite this higher complexity they are in line with lapse rates from stream water samples and in situ soil temperature measurements along the same transect our results demonstrate that both soil n alkane d values and mat reconstructions based on brgdgts distributions from the hillslope transect d 1 64 100 m r 2 0 91 p 0 01 and t 0 51 c 100 m r 2 0 91 p 0 01 track the direct effects of orography on precipitation and temperature and hence the combined effects of local and regional hydrology as well as elevation

influence of andean uplift on climate and paleoaltimetry estimates article i nfo article history recent elevation reconstructions of the andean plateau suggest a rapid 2 5 1 0 km rise of the central andes between 10 and 6 ma this rapid rise has been attributed to a catastrophic removal of a dense lithospheric mantle root beneath the andes however these findings are based on the assumption that climate did not change during deposition of paleoaltimetry proxies here we evaluate south american climate change due to andean uplift and its influence on interpretations of plateau elevation from climate sensitive paleoaltimetry data a series of experiments are presented using the regcm3 regional general circulation model rcm to characterize changes in andean precipitation amount surface temperature and wind direction vapor source as a function of changing plateau elevation results indicate that south american and andean climate changed significantly in response to plateau growth more specifically rising of the plateau results in up to a 900 mm increase in rainy season december january february precipitation over the plateau plateau uplift also results in a decrease in non adiabatic surface temperature of up to 6 5 c in addition to adiabatic cooling directly related to elevation change through the lapse rate finally the prevailing wind direction and the vapor source for precipitation switches from the south pacific ocean to the equatorial atlantic as plateau elevation increases above of its present day elevation taken together these changes in paleoclimate would have substantially depleted the oxygen isotopic concentration of paleoprecipitation through the cenozoic unless this climatic effect is taken into consideration paleoaltimetry reconstructions based on stable isotope methods may overestimate the rapid rise of the andes by up to several kilometers we conclude that some or all of the apparent rapid rise of the andean plateau from paleoaltimetry data could be an artifact of large changes in paleoclimate

controls on the isotopic composition of surface water and precipitation in the northern andes colombian eastern cordillera abstract empirical datasets provide the constraints on the variability and causes of variability in stable isotope compositions d or 18 o of surface water and precipitation that are essential not only for models of modern and past climate but also for investigations of paleoelevation this study presents stable isotope data for 76 samples from four elevation transects and three iaea gnip stations in the eastern cordillera of colombia and the northern andean foreland these data are largely consistent with theories of stable isotope variability developed based on a global dataset on a monthly basis the precipitation amount effect exerts the dominant control on d p and 18 o p values at the iaea gnip stations at the bogota station 2547 m the d p and 18 o p values vary seasonally with isotopic minima correlating with maxima in precipitation amount although surface water samples from eastern cordilleran streams and rivers fall on the global meteoric water line samples from three of four lakes 2842 3459 m have evaporatively elevated d sw and 18 o sw values the iaea gnip station data averaged over multiple years combined with stream and river water data define vertical lapse rates of 1 8 km 1 for 18 o and 14 6 km 1 for d and are a close fit to a common thermodynamically based rayleigh distillation model elevation uncertainties for these relationships are also evaluated comparison of this colombian dataset with the elevation uncertainties generated by the thermodynamically based model shows that the model underestimates uncertainty at high 18 o and d values while overestimating it for low 18 o and d values this study presents an independent empirical assessment of stable isotope based elevation uncertainties for the northern andes based on a dataset of sufficient size to ensure statistical integrity these vertical lapse rates and associated uncertainties form the basis for stable isotope paleoelevation studies in the northern andes

spatial temporal changes in andean plateau climate and elevation from stable isotopes of mammal teeth abstract paleoelevation constraints from fossil leaf physiognomy and stable isotopes of sedimentary carbonate suggest that significant surface uplift of the northern andean plateau on the order of 2 5 1 km occurred between 10 3 and 6 4 ma independent spatial and temporal constraints on paleoelevation and paleoclimate of both the northern and southern plateau are important for understanding the distribution of rapid surface uplift and its relation to climate evolution across the plateau this study focuses on teeth from modern and extinct mammal taxa including notoungulates pyrotheres and litopterns spanning 29 ma to present collected from the altiplano and eastern cordillera of bolivia 16 2 s to 21 4 s and lowland brazil tooth enamel of large water dependent mammals preserves a record of surface water isotopes and the type of plants that animals ingested while their teeth were mineralizing previous studies have shown that the 18o of modern precipitation and surface waters decrease systematically with increasing elevations across the central andes our results from high elevation sites between 3600 and 4100 m show substantially more positive 18o values for late oligocene tooth samples compared to