structure of a cold front over the ocean the kinematic and thermodynamic structure of a strong cold front over the gulf of alaska has been determined using aircraft dropsonde and radiosonde data obtained during the storm transfer and response experiment synoptic scale analysis using the sawyer eliassen secondary circulation equation shows that friction and diabatic heating as well as the geostrophic forcing are important in accounting for the secondary circulation at the front a fine scale analysis with horizontal resolution of 700m and vertical resolution of 100 m shows strong relative inflow of warm boundary layer air toward the front from the east and a weaker inflow of cold air from the west updraught velocities of greater than 6 m s 1 over a 2 km width were measured at 875 mb near the leading edge of the front the frontogenetical effects of confluence turbulent mixing and tilting of isentropic surfaces are evaluated in the region of the front and compared with the results of previous studies the high resolution of the thermodynamic fields provides new data for comparison with high resolution numerical models

influence of strong gradients of wind and humidity on frontal ageostrophic circulations the impact is studied of strong gradients of wind and humidity on the ageostrophic circulation developed around a conceptual cold frontal system the simulated basic wind and temperature fields are chosen to best represent the frontal observations made during the fronts 87 field experiment and in particular to take account of the presence of strong low level jets the numerical solution of the diagnostic sawyer eliassen equation in both its adiabatic and diabatic forms permitted us to test the impact of the wind and humidity structure on the corresponding ageostrophic circulation in particular strong negative shear above the low level jet core enhanced subsiding motions on the warm side of the front which restricted the horizontal extent of the cloud cover on the other hand the presence of well marked horizontal humidity gradients aloft at the rear edge of the cloud cover enhanced the ascending motions ahead of the frontal surface creating locally a secondary maximum of upward motions the degree of stability within the prefrontal boundary layer was found to be of major importance with regard to the intensification of the upright convection near the leading edge of the front moreover the incorporation of a parametrization scheme representing the ekman pumping at the top of the boundary layer enhanced the diagnosed circulation ahead of the front a comparison with observations made during two case studies of fronts 87 seems to confirm these results

a full coverage high resolution topographic model of greenland computed from a variety of digital elevation data in this paper a new high resolution elevation model of greenland including the ice sheet as well as the ice free regions is presented it is the first published full coverage model computed with an average resolution of 2 km and providing an unprecedented degree of detail the topography is modeled from a wide selection of data sources including satellite radar altimetry from geosat and ers 1 airborne radar altimetry and airborne laser altimetry over the ice sheet and photogrammetric and manual map scannings in the ice free region the ice sheet model accuracy is evaluated by omitting airborne laser data from the analysis and treating them as ground truth observations the mean accuracy of the ice sheet elevations is estimated to be 12 13 m and it is found that on surfaces of a slope between 0 2 and 0 8 corresponding to approximately 50 of the ice sheet the model presents a 40 improvement over models based on satellite altimetry alone on coastal bedrock the model is compared with stereo triangulated reference points and it is found that the model accuracy is of the order of 25 35 m in areas covered by stereo photogrammetry scannings and between 200 and 250 m elsewhere

microbial colonization of halite from the hyper arid atacama desert studied by raman spectroscopy the hyper arid core of the atacama desert chile is the driest place on earth and is considered a close analogue to the extremely arid conditions on the surface of mars microbial life is very rare in soils of this hyper arid region and autotrophic micro organisms are virtually absent instead photosynthetic micro organisms have successfully colonized the interior of halite crusts which are widespread in the atacama desert these endoevaporitic colonies are an example of life that has adapted to the extreme dryness by colonizing the interior of rocks that provide enhanced moisture conditions as such these colonies represent a novel example of potential life on mars here we present non destructive raman spectroscopical identification of these colonies and their organic remnants spectral signatures revealed the presence of uv protective biomolecules as well as light harvesting pigments pointing to photosynthetic activity compounds of biogenic origin identified within these rocks differed depending on the origins of specimens from particular areas in the desert with differing environmental conditions our results also demonstrate the capability of raman spectroscopy to identify biomarkers within rocks that have a strong astrobiological potential

over winter persistence of supraglacial lakes on the greenland ice sheet results and insights from a new model we present a newly developed 1 d numerical energy balance and phase transition supraglacial lake model glacierlake glacierlake incorporates snowfall in situ snow and ice melt incoming water from the surrounding catchment ice lid formation basal freeze up and thermal stratification snow cover and temperature are varied to test lake development through winter and the maximum lid thickness is recorded average wintertime temperatures of 2 to 30 circ rm c and total snowfall of 0 to 3 45 m lead to a range of the maximum lid thickness from 1 2 to 2 8 m after sim 250 days with snow cover exerting the dominant control an initial ice temperature of 15 circ rm c with simulated advection of cold ice from upstream results in 0 6 m of basal freeze up this suggests that lakes with water depths above 1 3 to 3 4 m dependent on winter snowfall and temperature upon lid formation will persist through winter these buried lakes can provide a sizeable water store at the start of the melt season expedite future lake formation and warm underlying ice even in winter

airborne doppler radar and sounding analysis of an oceanic cold front abstract an analysis of a cold front over the eastern atlantic ocean based on airborne doppler wind syntheses and dropsonde data is presented the focus and unique aspect of this study is a segment of the front that was near the center of the cyclone the dual doppler wind synthesis of the frontal zone combined with an average dropsonde spacing of 30 km covers a total distance of 450 km in the cross frontal direction the finescale resolution and areal coverage of the dataset are believed to be unprecedented the cold front was characterized by a distinct wind shift and a strong horizontal temperature gradient the latter was most intense aloft and not at the surface in contrast to the classical paradigm of surface cold fronts the shear of the alongfront component of the wind was relatively uniform as a function of height within the frontal zone this observation is contrary to studies suggesting that frontal zones decrease in intensity above the surface the surface convergence within the frontal zon

a comparison between frontogenesis in the two dimensional eady model of baroclinic instability and summertime cold fronts in the australian region a two dimensional anelastic numerical model with a simple turbulence parametrization is integrated with eady s linear normal mode solution for an unstable baroclinic wave as initial condition the structure of the surface front which develops after five days of model integration is compared with data on summertime cold fronts or cool changes in south eastern australia obtained during recent field experiments of the australian cold fronts research programme it is shown that the ridge trough structure of an amplifying baroclinic wave and its attendant surface front captures many of the important features of cool changes together with the broad scale flow in which they develop indeed it is argued that the model provides a useful theoretical framework in which the dynamics of the australian summertime cool change may be understood

a review of cold fronts with prefrontal troughs and wind shifts the conceptual model of a classical surface based cold front consists of a sharp temperature decrease coincident with a pressure trough and a distinct wind shift at the surface many cold fronts however do not conform to this model time series at a single surface station may possess a pressure trough and wind shift in the warm air preceding the cold front hereafter called a prefrontal trough and prefrontal wind shift respectively although many authors have recognized these prefrontal features previously a review of the responsible mechanisms has not been performed to date this paper presents such a review ten disparate mechanisms with different frontal structures have been identified from the previous literature these mechanisms include those external to the front i e those not directly associated with the cold front itself synoptic scale forcing interaction with lee troughs drylines interaction with fronts in the mid and upper troposphere and frontogenesis associated with inhomogeneities in the prefrontal air mechanisms internal to the front i e those directly associated with the structure and dynamics of the front include the following surface friction frontogenesis acting on alongfront temperature gradients moist processes descent of air ascent of air at the front and generation of prefrontal bores gravity waves given the gaps in our knowledge of the structure evolution and dynamics of surface cold fronts this paper closes with an admonition for improving the links between theory observations and modeling to advance understanding and develop better conceptual models of cold fronts with the goal of improving both scientific understanding and operational forecasting

antarctic paleolake sediments and the search for extinct life on mars evidence of lakes in mars history is substantial the proposed similarities between the ancient martian environment and certain modern environments on earth have led exobiologists to study antarctic lakes as analogs to those purported to have existed on mars we have investigated modern sedimentation processes especially with respect to 13c of carbonate and organic matter in lakes in the mcmurdo dry valleys region of east antarctica and assessed various paleolake deposits with respect to their utility as martian analogs and targets for future mars exobiology missions three main types of paleolake deposit were identified and assessed strand lines perched deltas and lacustrine sand mounds deltas are usually identified as good targets but our research shows that authigenic carbonates are not readily identifiable in the sediments large deltas although most likely to attract attention through remote sensing generally are difficult sites for discovery of paleobiological matter and 13c signals follow no coherent pattern lacustrine sand mounds on the other hand contain abundant authigenic carbonate and freeze dried organic matter and appear to be excellent records of paleolimnological conditions the advantage of studying lake bottom deposits versus lake edge deposits is retrieval of a stable lake wide signal deltas are therefore most useful in that they are generally large scale features capable of drawing attention to a region of potential for the discovery of smaller lacustrine sand mounds

diagnosing summertime mesoscale vertical motion implications for atmospheric data assimilation abstract balance omega equations have recently been used to try to improve the characterization of balance in variational data assimilation schemes for numerical weather prediction nwp results from fisher and fillion et al indicate that a quasigeostrophic omega equation can be used adequately in the definition of the control variable to represent synoptic scale balanced vertical motion for high resolution limited area data assimilation and forecasting 1 10 km horizontal resolution such a diagnostic equation for vertical motion needs to be revisited using a state of the art nwp forecast model at 2 5 km horizontal resolution these issues are examined starting from a complete diagnostic partial differential equation for omega the rhs forcing terms were computed from model generated fields these include the streamfunction temperature and physical time tendencies of temperature in gridpoint space to accurately compute one term of second order importance i e the ageostrophic vorticity tendenc

the role of forcing in cell morphology and evolution within midlatitude squall lines abstract this study assesses the role of mesoscale forcing on cell morphology and early evolution of midlatitude squall lines the forcing chosen was a cold front simulated to frontal collapse to produce a specific set of thermodynamic profiles at the leading edge of the front use of a realistic balanced and persistent forced state allowed a unique evaluation of its importance in thunderstorm evolution compared with a traditional homogeneous environment without forcing three dimensional squall lines were modeled with and without the front present in low and high bulk richardson number environments the forced convection evolved in significantly different ways than their isolated unforced counterparts in low shear conditions the line of isolated convective cells split with the adjacent split cells interfering destructively with neighboring cells in the line with forcing present differences in anticyclonic cell intensity and propagation prevented this interaction from occurring leading to longe

investigating the local atmospheric response to a realistic shift in the oyashio sea surface temperature front abstractthe local atmospheric response to a realistic shift of the oyashio extension sst front in the western north pacific is analyzed using a high resolution hr 0 25 version of the global community atmosphere model version 5 cam5 a northward shift in the sst front causes an atmospheric response consisting of a weak surface wind anomaly but a strong vertical circulation extending throughout the troposphere in the lower troposphere most of the sst anomaly induced diabatic heating is balanced by poleward transient eddy heat and moisture fluxes collectively this response differs from the circulation suggested by linear dynamics where extratropical sst forcing produces shallow anomalous heating balanced by strong equatorward cold air advection driven by an anomalous stationary surface low to the east this latter response however is obtained by repeating the same experiment except using a relatively low resolution lr 1 version of cam5 comparison to observations suggests that the hr respo

origin of modern dolomite in surface lake sediments on the central and western tibetan plateau abstract modern dolomite was found in the sediments of 20 lakes on the central and western tibetan plateau during lake surveys in august to november of 2012 2015 we analyzed the mineralogy of authigenic carbonates and the chemical composition of lake water to investigate the environmental factors affecting dolomite formation and to determine the mechanisms of dolomite formation x ray diffraction analysis suggested that the dolomite content ranged from 3 to 10 with a mean of 5 and that the majority of the dolomite in the surface lake sediments was ca dolomite dolomite formed in a wide range of salinity environments there was a positive linear relationship between salinity and mg ca ratio whereas the ph and sulfate so42 concentration are not significantly correlated with mg ca ratio high mg ca ratio high salinity high sulfate concentration and high ph are important environmental factors in favor of dolomite precipitation evaporation and microbial activity are potential mechanisms for dolomite formation in the central and western tibetan plateau the positive relationship between 18o and 13c indicates that the dolomite formed in lakes has a long residence time and undergoes continuous evaporation the crystal morphologies of dolomite were scattered euhedral grains with diameters of 2 10 m as well as sub spherical and spherical grains

near surface strong winds in a marine extratropical cyclone acceleration of the winds and the importance of surface fluxes a rapidly developing extratropical cyclone named tini brought strong winds to ireland and the united kingdom on 12 february 2014 a mesoscale model simulation is used to analyze the development of the strong winds through the terms in the horizontal momentum equation the maximum of near surface wind speed equatorward of the cyclone was composed of two different airstreams that underwent different paths to acceleration first horizontally moving air in the cold conveyor belt was accelerated by the along flow pressure gradient force but was decelerated by friction second descending air accelerated into the eastern end of the maximum of near surface wind speed and was associated in part with a sting jet caused by the increasing along flow horizontal pressure gradient force at lower levels when this descending air entered the boundary layer it too was decelerated by surface friction surface fluxes of heat and moisture were necessary to destabilize and deepen the boundary layer allowing mixing of the strongest winds from the free troposphere down to the surface a simulation with the surface fluxes turned off during cyclogenesis showed a more stable boundary layer around the bent back front which inhibited the strongest winds from reaching the surface the descent of the sting jet air was associated with a maximum in quasigeostrophic omega which consisted of both synoptic scale and mesoscale descent the latter associated with frontolysis occurring at the end of the bent back front thus the near surface wind maximum was created by the synoptic scale and mesoscale dynamics whereas localized moist processes were negligible

precipitation over greenland retrieved by a dynamic method and its relation to cyclonic activity abstract in order to calculate the vertical motion over some high mountain regions such as greenland an equation without the quasigeostrophic approximation in coordinates has been developed a dynamic method for retrieving precipitation over greenland is based on this equation the retrieved annual mean precipitation distribution for 1987 and 1988 is in very good agreement with the observed annual accumulation pattern over the greenland ice sheet the major weather system producing precipitation over greenland is the frontal cyclone based on the precipitation characteristics greenland can be divided into five subregions precipitation over the north coastal and central interior regions primarily occurs in summer for the three other subregions if the composite monthly mean sea level pressure charts for high and low monthly precipitation amounts are constructed a clear relationship between precipitation and cyclonic activity emerges if a mean cyclone exists in the labrador sea heavy precipita

detailed description of deformation induced semi geostrophic frontogenesis examen dans la limite de la semi geostrophie d une variante du probleme classique de la frontogenese de surface induite par la deformation le systeme particulier d ecoulement considere constitue la reponse a un champ de deformation donne d une atmosphere barocline semi infinie stratifiee et a vorticite potentielle uniforme resultats obtention d une classe de solutions analytiques simples dans l espace geostrophique obtention d une solution explicite de l equation de sawyer eliassen relative a la circulation ageostrophique obtention d une equation autonome non lineaire dans l espace reel relative au developpement a la surface de la composante du vent alignee le long du front application aux divers aspects frontogenes a savoir l echelle temporelle du developpement du front la co occurrence des differents types frontaux la pente et le mouvement des figures frontales la structure et la force de la circulation ageostrophique et le degre de validite de l approximation semi geostrophique

discrete frontal propagation in a nonconvective environment abstract surface discrete frontal propagation in a wintertime nonconvective environment is documented using conventional surface and upper air data and simulated using the psu ncar mesoscale model synoptic and mesoscale surface analyses show a cold front associated with a synoptic scale low pressure system propagating from northwest to southeast across the central united states apparently discrete frontal propagation occurs when the surface front dissipates and a new front forms approximately 500 km ahead of the original front with no compelling evidence of frontal passage in the intervening space upper air analyses indicate the infusion of three different airstreams into the frontal region resulting in the formation of a ribbon of low static stability air parallel to and several hundred kilometers in advance of the original front this static stability structure appears to be involved in the observed evolution of the front the development of precipitation over the intervening zone between the old

defining biominerals and organominerals direct and indirect indicators of life abstract by introducing the new term organomineral to apply to minerals that are affected by organics mostly life related but not directly produced by living cells we hope to increase the accuracy of the terminology in present usage we believe that the term biomineral does not describe all mineral deposits precisely enough and offer case studies to support instances where the use of the new term organomineral is more appropriate we provide examples of some materials that are biominerals such as those in diatoms and human bones and which perform a functional purpose we then attempt to show that terminology can sometimes mislead investigators drive the direction and prejudice interpretations of scientific investigation this is achieved by presenting case studies of minerals that have been investigated as biominerals although they may not actually be directly controlled by biology for this reason we pay special attention to desert varnish hot spring siliceous deposits stromatolites and bacterial encrustations we go on to explain why we regard biominerals as direct indictors of life whereas organominerals should be treated as indirect indicators of life that require careful characterization to establish the origin of contained organics and whether these are biotic in origin how organic compounds are preserved and transformed in sedimentary environments and in the mineral matrix is as highly relevant to the study of modern earth environments as it is in the search for the oldest evidence of life in the terrestrial rock record it is also important to many disciplines such as microbiology and archaeology and especially to scientists planning missions to look for evidence of life on other planetary surfaces

modeled variations of precipitation over the greenland ice sheet abstract a parameterization of the synoptic activity at 500 hpa and a simple orographic scheme are used to model the spatial and temporal variations of precipitation over the greenland ice sheet for 1963 88 from analyzed geopotential height fields produced by the national meteorological center nmc model coefficients are fitted to observed accumulation data primarily from the summit area of the ice sheet all major spatial characteristics of the observed accumulation distribution are reproduced apart from the orographic accumulation maximum over the northwestern coastal slopes the modeled time averaged total precipitation amount over greenland is within the range of values determined by other investigators from surface based observations a realistic degree of interannual variability in precipitation is also simulated a downward trend in simulated ice sheet precipitation over the 26 years is found this is supported by a number of lines of evidence it matches the accumulation trends during this peri

raman spectroscopic detection of key biomarkers of cyanobacteria and lichen symbiosis in extreme antarctic habitats evaluation for mars lander missions with proposals that micro miniaturised raman spectrometers could soon be part of a suite of analytical instrumentation on the surface of mars it is critically important to examine the spectral information that could be forthcoming from attempts to determine key molecular biosignatures under the hostile conditions of extra terrestrial planetary exploration current approaches include the analysis of genuine martian geological material in the form of the snc class meteorites the formulation of simulated martian regoliths and the examination of putative martian terrestrial analogues the latter provide the basis of this paper in the form of antarctic extremophile habitats in particular specimens of epilithic chasmolithic and endolithic lichen and cyanobacterial colonies sampled along a progressively worsening transect towards a limits of life situation beyond which survival of organisms becomes impossible provide what is arguably the best terrestrial proving ground for prototype raman spectrometers for martian exploration here we report the results of experiments on these extant antarctic extremophile colonies using a range of raman excitation wavelengths and experimental conditions and also include a compilation of molecular spectral biosignatures which may be considered as a suitable database for recognition of bioorganic modification of geological strata

multiyear accumulation and temperature history near the north greenland ice core project site north central greenland this paper presents a comparison of two independent methods of estimating subseasonal accumulation across the interior of greenland these methods high resolution snow pit studies and atmospheric modeling have differing spatial and temporal resolution but both can estimate net accumulation for subseasonal and shorter periods the snow pit approach is based on a documented relationship between high resolution snow pit profiles of oxygen stable isotope ratio 18o and multiyear special sensor microwave imager ssm i 37 ghz brightness temperature records comparison of ssm i data to profiles obtained during the 1995 alfred wegener institut north greenland traverse field season shows that 18o data from snow in north central greenland are a reliable high resolution temperature proxy this enables determination of accumulation amount rate and timing from approximately july 1991 through june 1995 across this 220 km long transect of the ice sheet precipitation estimates derived from early modeling based on european centre for medium range weather forecasts data show a similar average seasonal pattern but a diminished magnitude of accumulation 56 for these sites the slope of the multiyear t versus correlation was evaluated for each site on the basis of the observed and calculated temperature history from the nearby north greenland ice core project ngrip site automatic weather station these data should assist interpretation of the paleoclimatic record in the ngrip deep core

rapid thinning of parts of the southern greenland ice sheet aircraft laser altimeter surveys over southern greenland in 1993 and 1998 show three areas of thickening by more than 10 centimeters per year in the southern part of the region and large areas of thinning particularly in the east above 2000 meters elevation the ice sheet is in balance but thinning predominates at lower elevations with rates exceeding 1 meter per year on east coast outlet glaciers these high thinning rates occur at different latitudes and at elevations up to 1500 meters which suggests that they are caused by increased rates of creep thinning rather than by excessive melting taken as a whole the surveyed region is in negative balance

raman spectroscopy of the dukhan sabkha identification of geological and biogeological molecules in an extreme environment the characterization of minerals and biogeological deposits in a terrestrial arabian sabkha has a direct relevance for the exploration of mars since the discovery by the nasa rovers spirit and opportunity of evaporate minerals on mars that could have arisen from aquifers and subsurface water movement the recognition of carbonates and sulphates in gusev crater has afforded an additional impetus to these studies as relict or extant microbial extremophilic organisms could have colonized these geological matrices as has been recorded on earth here we describe the raman spectroscopic analysis of specimens of evaporitic materials sampled from the dukhan sabkha the largest inland sabkha in the persian gulf with daily temperatures reaching in excess of 60 c and extreme salinity we have identified the characteristic raman signatures of key biomolecular compounds in association with evaporitic minerals and geological carbonate and sulphate matrices which indicate that extremophilic cyanobacterial colonies are existent there this evidence the first to be acquired spectroscopically from such a region establishes a platform for further studies using remote portable raman instrumentation that will inform the potential of detection of similar systems on the martian surface or subsurface in future space missions a comparison is made between the results from this study and the previous analysis of a gypsum halite sabkha where the extremophilic molecular signatures were better preserved

greenland ice sheet surface mass balance variability 1991 2003 the polar mm5 mesoscale atmospheric model was run for 13 years 1991 2003 over greenland at 24 km horizontal resolution box and others 2004 the model physics were driven by satellite station and weather balloon observational data assimilation i e european centre for medium range weather forecasts ecmwf operational analysis the analysis in this study focuses on the response of the surface mass balance to its primary controls temperature and precipitation the results indicate coherent spatial patterns of variability and statistically significant links with temperature and precipitation and the north atlantic oscillation precipitation trends have the same spatial pattern and sign as temperature suggesting an association of precipitation and temperature variability increasing temperatures contribute to an increasing ablation trend and expansion of the ablation zone despite increasing accumulation trends the pinatubo philippines volcanic cooling in the early 1990s enhances this apparent warming trend only in the northeast does precipitation appear to dominate the surface mass balance where both temperature and precipitation have decreased there is little evidence for a total ice sheet surface mass balance trend although the meltwater runoff has a positive trend and combined with iceberg discharge and basal melting estimates suggests the ice sheet as a whole is in a state of net mass loss over this period

meso α and meso β network analyses of a severe storm complex during sesame ave v presented in this paper are meso and meso network analyses of thermodynamics and kinematics related to the formation of a severe storm complex on 20 may 1979 during sesame ave v the storm organizes in the mesonetwork by mid afternoon ahead of a nearly east west aligned quasistationary pressure trough by mid morning a tongue of high mixing ratios develops south of the trough in northern texas and southern oklahoma in response to strong differential solar heating and the moist tongue a pronounced low level e maximum appears in this region convective activity to the south of the trough is inhibited by a low level stable layer in the region sinking motion aloft enhances the stable layer at midday the pressure trough accelerates southward and intensifies strengthening low level convergence which in turn induces a well defined vertical circulation in the meso network the vertical motion in the circulation pushes the air to its lifting condensation level and the convective instability is released

the role of diabatic heating in maintaining the upper tropospheric baroclinic zone in the south pacific a modified set of ecmwf fgge level iii b analyses is used to examine the four dimensional structure of the region containing the south pacific convergence zone spcz during a period when two cyclones form in the tropics and propagate south eastward along the spcz into middle latitudes during this period 10 18 january 1979 the atmosphere is characterized by a highly baroclinic state which together with the existence of an upper tropospheric subtropical jet supports the growth and development of the observed cyclone activity in a previous study it was found that convective activity was prominent during the life cycle of each cyclone the goal of the present study is to examine the significance of kinematic and thermodynamic processes in maintaining the upper baroclinic region coincident with the subtropical jet this baroclinic zone lies just poleward of the warm core associated with the convectively active spcz a partitioned form of the fronto genetical function is used to diagnose the adiabatic and diabatic contributions to the maintenance of baroclinicity in the vicinity of the spcz a major balance is found between the frontogenetical contribution by differential diabatic heating and the opposing diabatic tilting processes in contrast to the results of most mid latitude cyclone studies the adiabatic contributions from the deformation and tilting terms appear to be of lesser importance also the contribution from the deformation associated with the horizontal branch of the diabatically forced circulation is found to be relatively unimportant the latter finding is in disagreement with some previously reported numerical results concerned with middle latitude moist frontogenesis possible reasons for these differences are discussed

asiras airborne radar resolves internal annual layers in the dry snow zone of greenland 1 we present data from the european space agency s airborne sar interferometric radar altimeter system asiras flown during the cryovex 2004 field calibration validation campaign and new high resolution depth profiles of snow density measured in the field by neutron scattering we combine these data to calculate the depth of internal reflecting horizons in the asiras data the high resolution density data allow us to identify annual layers in the snow density profile and correlate their peaks with the reflecting horizons we use the thickness of the annual layers combined with the density profile to determine the spatial and temporal pattern of snow accumulation along the radar track for a period of 6 years from 1995 2002 our mean annual accumulation rate is 0 47 0 09 ma 1 water equivalent in agreement with the value determined from a core taken in this location in 1992 similarly our inter annual variability shows the same trends as recent model estimates over the entire ice sheet because asiras was designed to mimic as closely as possible the characteristics of the sar interferometric radar altimeter siral the principal payload of cryosat the detection of internal layering with asiras illuminates the possibility of detecting internal layers with a space borne radar and thus the possible application of this technique to the dry snow zones of antarctica greenland and smaller ice bodies

separation of climatological imprints of the kuroshio extension and oyashio fronts on the wintertime atmospheric boundary layer their sensitivity to sst resolution prescribed for atmospheric reanalysis abstractmesoscale structures of the wintertime marine atmospheric boundary layer mabl as climatological imprints of oceanic fronts within the kuroshio oyashio extension koe region east of japan are investigated by taking advantage of high horizontal resolution of the era interim global atmospheric reanalysis data for which the resolution of sea surface temperature sst data has been improved these imprints including locally enhanced sensible and latent heat fluxes and local maxima in cloudiness and precipitation in association with locally strengthened surface wind convergence in the vicinities of sst fronts along the warm kuroshio extension and cool oyashio to its north are also identified in high resolution satellite data in addition to these mesoscale mabl features meridionally confined near surface baroclinic zones and zonally oriented sea level pressure slp minima associated with the dual sst fronts are represented in era interim only in the period of high resolution sst but those impri

biomarkers and their raman spectroscopic signatures a spectral challenge for analytical astrobiology the remote robotic exploration of extraterrestrial scenarios for evidence of biological colonization in search for life missions using raman spectroscopy is critically dependent on two major factors firstly the raman spectral recognition of characteristic biochemical spectral signatures in the presence of mineral matrix features and secondly the positive unambiguous identification of molecular biomaterials which are indicative of extinct or extant life both of these factors are considered here the most important criterion is the clear definition of which biochemicals truly represent biomarkers whose presence in the planetary geological record from an analytical astrobiological standpoint will unambiguously be indicative of life as recognized from its remote instrumental interrogation also discussed in this paper are chemical compounds which are associated with living systems including biominerals which may not in themselves be definitive signatures of life processes and origins but whose presence provides an indicator of potential life bearing matrices

modeled precipitation variability over the greenland ice sheet on the basis of the evaluation of recent greenland precipitation studies some of the deficiencies in the modeled precipitation are probably related to the topographic data employed in modeling in this paper the modern digital elevation data of ekholm 1996 is used if the horizontal pressure gradient force in coordinates is separated into its irrotational and rotational parts which are expressed by the equivalent geopotential and geo stream function respectively the topographic effect on the precipitation can be accurately modeled the equivalent geopotential and geo stream function are implemented in a fully consistent manner in the generalized equation in this paper a simplified large scale condensation without evaporation of condensate is also used these improvements are combined to yield an improved dynamic method two aspects of the precipitation distribution are refined by the improved dynamic method one is the 10 cm yr 1 contour near summit greenland and the other is a relative large precipitation area centered near the point 70 n 49 w extensive comparisons are made between the retrieved precipitation and the observed annual accumulation time series from 11 ice core sites on the ice sheet the modeled precipitation from the original method must use sealers to have a high degree of interannual correspondence between the measured accumulation and the retrieved precipitation but the retrieved precipitation from the improved method increases at all ice core sites and a good correspondence is obtained without any sealer being required the spatial average of multiyear mean error e j is 11 5 cm yr 1 for the modeled precipitation from the improved method while that for p from era 15 is 14 5 cm yr 1 the total mean error em is 3 0 cm yr 1 for the improved method while em for the p from era 15 is 4 0 cm yr 1 these two errors show that the precipitation modeled by the improved method is better than the p from era 15 thus the distribution of precipitation over the 11 sites retrieved by the improved dynamic method is considerably refined large downward trends in annual amounts are present in the precipitation retrieved by the improved dynamic method for all of greenland and its southern and central west coastal regions the modeled precipitation from the improved dynamic method and observed accumulation from ice cores are all in agreement with the thomas et al 1999 result that the southern greenland ice sheet above 2000 m is approximately in balance it also shows that local thickening and thinning areas of the ice sheet derived by airborne laser altimetry from 1993 to 1999 over the entire greenland above 2000 m krabill et al 2000 are approximately consistent with precipitation change retrieved by the improved dynamic method

greenland ice sheet high elevation balance and peripheral thinning aircraft laser altimeter surveys over northern greenland in 1994 and 1999 have been coupled with previously reported data from southern greenland to analyze the recent mass balance of the greenland ice sheet above 2000 meters elevation the ice sheet is in balance on average but has some regions of local thickening or thinning thinning predominates at lower elevations with rates exceeding 1 meter per year close to the coast interpolation of our results between flight lines indicates a net loss of about 51 cubic kilometers of ice per year from the entire ice sheet sufficient to raise sea level by 0 13 millimeter per year approximately 7 of the observed rise

changes in greenland ice sheet elevation attributed primarily to snow accumulation variability the response of grounded ice sheets to a changing climate critically influences possible future changes in sea level recent satellite surveys over southern greenland show little overall elevation change at higher elevations but large spatial variability using satellite studies alone it is not possible to determine the geophysical processes responsible for the observed elevation changes and to decide if recent rates of change exceed the natural variability here we derive changes in ice sheet elevation in southern greenland for the years 1978 88 using a physically based model of firn densification and records of annual snow accumulation reconstructed from 12 ice cores at high elevation our patterns of accumulation driven elevation change agree closely with contemporaneous satellite measurements of ice sheet elevation change and we therefore attribute the changes observed in 1978 88 to variability in snow accumulation similar analyses of longer ice core records show that in this decade the greenland ice sheet exhibited typical variability at high elevations well within the long term natural variability our results indicate that a better understanding of ice sheet mass changes will require long term measurements of both surface elevation and snow accumulation

dolomite occurrence evolution and economically important associations abstract dolomite is not a simple mineral it can form as a primary precipitate a diagenetic replacement or as a hydrothermal metamorphic phase all that it requires is permeability a mechanism that facilitates fluid flow and a sufficient supply of magnesium dolomite can form in lakes on or beneath the shallow seafloor in zones of brine reflux and in early to late burial settings it may form from seawater from continental waters from the mixing of basinal brines the mixing of hypersaline brine with seawater or the mixing of seawater with meteoric water or via the cooling of basinal brines bacterial metabolism may aid the process of precipitation in settings where sulfate reducing species flourish and microbial action may control primary precipitation in some hypersaline anoxic lake settings dolomite is a metastable mineral early formed crystals can be replaced by later more stable phases with such replacements repeated a number of times during burial and metamorphism each new phase is formed by the partial or complete dissolution of an earlier dolomite this continual re equilibration during burial detracts from the ability of trace elements to indicate depositional conditions and resets the oxygen isotope signature of the dolomite at progressively higher temperatures because subsurface dolomite evolves via dissolution and reprecipitation a bed of dolomite can retain or create porosity and permeability to much greater burial depths and into higher temperature realms than a limestone counterpart dolomitization also creates new crystals with new rhomb growth following the dissolution of less stable precursors repetition of this process without complete pore cementation can generate intercrystalline porosity a number of times in the rock s burial history intercrystalline porosity is a highly interconnected style of porosity that gives dolomite reservoirs their good fluid storage capacity and efficient drainage the fact that many dolomite reservoirs formed via brine reflux means that they sit beneath an evaporite seal in both platform and basinwide evaporite settings the same association of evaporites sulfate source and entrained hydrocarbons means that burial conditions are also suitable for thermochemical sulfate reduction and the precipitation of base metals this tends to occur at higher temperatures 60 c 80 c and so the resulting dolomites tend to be ferroan and consist of saddle shaped crystals

modeled antarctic precipitation part ii enso modulation over west antarctica the impacts of the el nino southern oscillation enso on the antarctic region are of special importance in evaluating the variability and change of the climate system in high southern latitudes in this study the enso signal in modeled precipitation over west antarctica since 1979 is evaluated using forecast precipitation from several meteorological analyses and reanalyses additionally a dynamical retrieval method drm for precip itation is applied over the last two decades the southern oscillation index soi has an overall anticorrelation with precipitation over the west antarctic sector bounded by 758 908s 1208w 1808 while it is positively correlated with precipitation over the south atlantic sector bounded by 658 758s 308 608w decadal variations are found as the relationship between the soi and west antarctic precipitation is stronger in the 1990s than that in the 1980s the polar front jet stream west antarctic precipitation and the soi show a well ordered correspondence during the 1990s as the jet zonal speed is negatively correlated to the soi and positively correlated to west antarctic precipitation these relationships are weaker during the 1980s consistent with the change in sign of the correlation between the soi and west antarctic precipitation the decadal variations are apparently related to changes in the quasi stationary eddies that determine the local onshore and offshore flow over west antarctica

an early autumn polar low formation over the norwegian sea around october 15 1993 an unusual polar low formation took place over the norwegian sea the evolution is studied by means of the hirlam forecasting model at the danish meteorological institute satellite imagery and observations the investigation to some extent based on generalized forms of the equations for omega and geopotential tendency reveals that the disturbance forms initially by baroclinic instability along a frontal zone within a maritime polar air mass and in close proximity of an intense extratropical cyclone during its growth to a polar low air sea interaction seems to work in conjunction with the baroclinic process a parallel forecast with the latent heat set to zero shows that heating of the atmosphere associated with precipitation is necessary for the polar low formation

snowmelt on the greenland ice sheet as derived from passive microwave satellite data abstract the melt extent of the snow on the greenland ice sheet is of considerable importance to the ice sheet s mass and energy balance as well as arctic and global climates by comparing passive microwave satellite data to field observations variations in melt extent have been detected by establishing melt thresholds in the cross polarized gradient ratio xpgr the xpgr defined as the normalized difference between the 19 ghz horizontal channel and the 37 ghz vertical channel of the special sensor microwave imager ssm i exploits the different effects of snow wetness on different frequencies and polarizations and establishes a distinct melt signal using this xpgr melt signal seasonal and interannual variations in snowmelt extent of the ice sheet are studied the melt is found to be most extensive on the western side of the ice sheet and peaks in late july moreover there is a notable increasing trend in melt area between the years 1979 and 1991 of 4 4 per year which came to an abrupt halt in 1

diabatically driven discrete propagation of surface fronts a numerical analysis discrete frontal propagation has been identified as a process whereby a surface front discontinuously moves forward without evidence of frontal passage across a mesoscale region numerical simulations are employed to examine the upper level evolution of a discrete frontal propagation event and to explore the processes that were responsible for the discrete movement model results indicate that a frontal pressure trough was not able to penetrate through a deep surface based layer of cool air created by a precipitating convective system several hundred kilometers in advance of the front meanwhile a new low level baroclinic zone formed well ahead of the front along the southern side of the cool layer as the midlevel front moved continuously over the cool layer a new low level front developed in the new baroclinic zone and the original low level front dissipated at the surface the simulated front did not pass through the cool layer frontogenesis terms reveal that the prefrontal circulation that becomes the new frontal circulation initially forms directly from diabatic frontogenesis daytime heating in the prefrontal boundary layer and cooling from thunderstorms combine to create a thermal gradient and a mesoscale pressure perturbation winds turn in response to the altered pressure field and form a convergent boundary resulting in kinematic frontogenesis the boundary subsequently undergoes rapid intensification sensitivity studies were conducted in which latent heating due to precipitation was withheld and the influence of clouds on the radiation scheme was ignored in a simulation with both of these effects withheld the original front passes continuously through the region that is there is no discrete propagation thus diabatic processes associated with a large complex of thunderstorms were necessary to induce the discrete frontal propagation in this case this conclusion contrasts with previous studies where fronts were observed to propagate discretely in dry environments

interannual variations of snow accumulation on the greenland ice sheet 1985 1996 new observations versus model predictions newly measured time series of net water equivalent accumulation from ice cores are reported for 11 sites located near the 2000 m contour of the greenland ice sheet many of these sites are located in regions where accumulation has not been previously measured we compared these new time series of annual accumulation with previously reported modeled precipitation covering the same time range because ice core accumulation records include both regional and local accumulation components we used adjacent ice core records at six multiple core sites to estimate the local component and extrapolated these results to the five single core sites we investigated the impact of this short scale spatial variability in accumulation on statistical comparisons between the observed accumulation and model precipitation although sealers were required to match the 12 year mean modeled precipitation to the mean observed accumulation a high degree of correspondence between observed interannual accumulation and scaled modeled precipitation was found at 7 of 11 locations the need for scaling and the low correspondence between model simulations and observations at some sites clearly indicate that model improvements are needed although very encouraging a more spatially distributed array of ice core accumulation measurements spanning the same time period as the precipitation modeling is necessary for continued model improvement and validation in agreement with earlier studies the large temporal variability in snow accumulation predicted by modeling and confirmed by ice cores indicates that the ice sheet elevation varies by tens of centimeters from year to year simply because of changing accumulation

penecontemporaneous dolomitization in sabkha faishakh qatar evidence from changes in the chemistry of the interstitial brines abstract studies in sabkha faishakh on the west coast of qatar in the early 1960s showed that much of the aragonite sabkha sediment has been converted to cryptocrystalline and microcrystalline dolomite in the last few thousand years under the influence of its interstitial lagoon derived brines whose mg ca ratio was boosted by the precipitation of gypsum illing et al 1965 because of the comparatively simple hydrological system in the part of the sabkha studied we have been able to show from chemical analyses of water samples collected along a 2 km line of pits across the sabkha that as dolomitization proceeds the brines lose magnesium and sulfate ions in a nearly one to one ratio in conformity with the reaction 2caco3 mg so4 camg co3 2 caso4 2h2o the radical losses were determined by assuming that the chloride content of the brines changes solely as a function of evaporation the correlation coefficient of magnesium vs sulfate losses in 17 water samples analyzed is 0 98 and the slope of the line is 0 89 changes in the bulk mineralogical composition of the sediment confirm the production of approximately equivalent amounts of dolomite and gypsum as put forward by klement nearly a hundred years ago

numerical simulations of maritime frontogenesis abstract a hydrostatic primitive equation model initialized in a highly baroclinically unstable state was used to simulate maritime cyclogenesis and frontogenesis in order to identify boundary layer physical processes important in maritime frontogenesis several different simulations were performed in an effort to isolate impacts due solely to the boundary layer moist processes were not included an adiabatic and inviscid simulation provided the control for these experiments two different boundary layer parameterizations were used a k theory parameterization featuring richardson number dependent eddy diffusivity and a second order closure scheme with prognostic equations for the turbulence quantities results indicated that strong warm and cold fronts formed in the adiabatic and inviscid case but that the vertical motion fields were weak in the k theory simulation the results were somewhat more realistic with stronger vertical motion in both the k theory and second order closure simulations the b

surviving the limits to life at the surface of mars the harshness of the environment at its surface severely limits the survival of unprotected terrestrial organisms on mars however the martian geologic record is consistent with an earlier history with much different climatic conditions more conducive to life followed by an extended climate change which led to the currently inhospitable state such a transition is ideal for evolutionary adaptation to new conditions because it provides both the forcing function and the extensive time for progressive specializations it is shown that against each of the current limits to life organics deprivation restricted amounts and physical forms of h2o limited availability of other key nutrients ionizing radiation insult and strongly oxidizing chemical species there are plausible countermeasure solutions most but not all of these mechanisms already exist as known examples in terrestrial biota a combination of these adaptations could conceivably allow highly tailored organisms either active or dormant to survive at or very near the surface of mars even in carefully preserved regolith samples returned to earth microorganisms could be difficult to detect without specific biochemical probes and or purposeful biological amplification by selective enhancement of the supply of nutrients optimized incubation parameters and highly sensitive detection of metabolic activity

structure of the cold front observed in sesame ave iii and its comparison with the hoskins bretherton frontogenesis model abstract a cold front which passed through the dense network of the sesame ave severe environmental storms and mesoscale experiment atmospheric variability experiment on 25 26 april 1979 was investigated rawinsonde data collected from 23 special stations and 19 national weather service stations at three hour intervals for a 24 hour period were used along with hourly surface data radar summary charts and goes east satellite images severe storms formed along the surface front during this period the analysis focused on the vertical circulation across the frontal surface at low levels the major features of the cold frontal system that emerged from an analysis of this unique data set include a familiar direct vertical circulation with moist warm air ascending just above the surface front however the upgliding motion was intercepted by a secondary circulation at middle levels the analysis result was compared with model predictions of hoskins and bretherton 1972 as calculated by blumen 1980 sever

a comparison of quasigeostrophic and nonquasigeostrophic vertical motions for a model simulated rapidly intensifying marine extratropical cyclone abstract large scale departures from quasigeostrophic vertical motions are diagnosed for a model simulation of the qe ii storm 9 11 september 1978 the simulation was performed by the limited area mesoscale prediction system lamps initialized at 1200 utc 9 september 1978 the model cyclone intensified from a central pressure of 1003 mb to 976 mb in 24 h considerably short of the 59 mb 24 h 1 observed deepening but reasonable in comparison to other model simulations of this storm this diagnosis centers on a hydrostatic generalized omega equation which scales to the quasigeostiophic omega equation for small rossby number vertical motions were computed both from this generalized omega equation and the quasigeostrophic omega equation in order to examine the importance of nonquasigeostrophic effects the high correlation of vertical motions from a control experiment using most of the terms in the generalized omega equation with the vertical motions predicted by the model establishes the validity o

evaluation of recent precipitation studies for greenland ice sheet the retrieval of an accurate spatial and temporal record of contemporary greenland precipitation is a uniquely challenging task because of the extreme variability in both atmospheric processes and the resulting precipitation distribution over relatively small spatial scales a comparison of precipitation data sets composed of monthly mean values from recent studies shows a convergence on the general features of the long term spatial patterns but substantial disagreement on the temporal variability both regionally and for all of greenland there is general agreement on a long term greenland average of about 35 cm yr 1 and on long term values for regional scales although differences for outlying data sets exceed 50 of the observed glaciological estimate for particular regions a fundamental problem is the inadequate topographic representation of greenland in the numerical analyses nearly all of the data sets are overly dry for high elevation areas as seen from comparisons with glaciological observations from summit the east central region of greenland is found to be particularly susceptible to the temporal discontinuities in data sets which employ operational analyses in contrast there is strong agreement among all methods on the temporal variability for the west central region over a 15 year period from the comparison it is concluded that none of the data sets is able to capture all of the regional scale features in general however the deficiencies of each data set are readily identifiable from comparison and evaluation in the context of circulation features agreement among the methods on particular regions and timescales gives increased confidence in drawing conclusions related to aspects of greenland s precipitation climatology in particular an enhanced precipitation retrieval method is found to be less susceptible to data artifacts than other methods using operational analyses in the north anomalously high precipitation is associated with cyclonic development near the fram strait for west central greenland the close agreement among methods is related to the dominant contribution of the mean circulation

diagnosing mesoscale vertical motion from horizontal velocity and density data the mesoscale vertical velocity is obtained by solving a generalized omega equation equation using density and horizontal velocity data from three consecutive quasi synoptic high resolution surveys in the alboran sea the atlantic jet aj and the northern part of the western alboran gyre wag were observed as a large density anticyclonic front extending down to 200 230 m the horizontal velocity uh in the aj reached maxima of 1 2 m s 1 for the three surveys with extreme rossby numbers of f 0 9 in

raman spectroscopy of volcanic lavas and inclusions of relevance to astrobiological exploration volcanic eruptions and lava flows comprise one of the most highly stressed terrestrial environments for the survival of biological organisms the destruction of botanical and biological colonies by molten lava pyroclastic flows lahars poisonous gas emissions and the deposition of highly toxic materials from fumaroles is the normal expectation from such events however the role of lichens and cyanobacteria in the earlier colonization of volcanic lava outcrops has now been recognized in this paper we build upon earlier raman spectroscopic studies on extremophilic colonies in old lava flows to assess the potential of finding evidence of biological colonization in more recent lava deposits that would inform first the new colonization of these rocks and also provide evidence for the relict presence of biological colonies that existed before the volcanism occurred and were engulfed by the lava in this research samples were collected from a recent expedition to the active volcano at kilauea hawaii which comprises very recent lava flows active fumaroles and volcanic rocks that had broken through to the ocean and had engulfed a coral reef the raman spectra indicated that biological and geobiological signatures could be identified in the presence of geological matrices which is encouraging for the planned exploration of mars where it is believed that there is evidence of an active volcanism that perhaps could have preserved traces of biological activity that once existed on the planet s surface especially in sites near the old martian oceans

airborne radar observations of a cold front during fastex1 abstract a detailed analysis using airborne doppler radars of an oceanic cold front associated with precipitation core and gap regions is presented the precipitation cores appear to form as a result of the combined effects of horizontal shearing instability and the advection of hydrometeors by the core relative winds in contrast to previous schematic models it is shown that a strong surface discontinuity does not exist along the entire length of the precipitation core the southern section of the core can be accompanied by an abrupt discontinuity and lighter precipitation while the northern section can be associated with more slowly changing variables but heavier precipitation the peak updrafts at the leading edge of the front appeared to be primarily driven by frictional convergence and the acceleration of the vertical vorticity in the boundary layer the overall motion of the cold front was not well predicted using density current theory even though the kinematic structure of the front resembled cla

precipitation over greenland and its relation to the north atlantic oscillation the equation method based on an equivalent isobaric geopotential height in coordinates has been used to retrieve the precipitation over greenland this approach is designed to accurately represent the topographic effects of the greenland ice sheet on atmospheric motion and precipitation the 11 year mean precipitation from 1985 to 1996 over all of greenland is 376 mm yr 1 which is close to the long term mean precipitation of 346 mm yr 1 estimated from glaciological data the precipitation over all of greenland shows that the largest value in 1986 is 472 mm yr 1 and the smallest value in 1995 is 309 mm yr 1 the major interannual variability of the atmospheric circulation in the north atlantic can be represented by the variation of the north atlantic oscillation nao index which is most pronounced during winter it is found that if the nao index increases the total precipitation over greenland decreases and vice versa the correlation coefficient between these two series for 1985 1995 is 0 75 the mean precipitation over southern greenland where the majority of precipitation falls is more closely related to the nao index in winter and their correlation coefficient is 0 80 this relationship can be understood from the composite maps of sea level pressure and greenland precipitation for the high and low index months during months of high nao index values the icelandic low is strong during months of low nao index values the monthly mean low is located to the southwest of greenland over the labrador sea precipitation amounts over the southeast coast of greenland are about 100 mm larger during the low nao index months than the high nao index months precipitation over all of greenland during the low nao index months is higher there are significant downward trends in annual precipitation from 1985 1995 for all of greenland and its southern and central west coastal regions amounting to about 3 per year

mass changes of the greenland and antarctic ice sheets and shelves and contributions to sea level rise 1992 2002 changes in ice mass are estimated from elevation changes derived from 10 5 years greenland and 9 years antarctica of satellite radar altimetry data from the european remote sensing satellites ers 1 and 2 for the first time the dh dt values are adjusted for changes in surface elevation resulting from temperature driven variations in the rate of firn compaction the greenland ice sheet is thinning at the margins 42 2g t a 1 below the equilibrium line altitude ela and growing inland 53 2g t a 1 above the ela with a small overall mass gain 11 3g t a 1 0 03 mm a 1 sle sea level equivalent the ice sheet in west antarctica wa is losing mass 47 4g t a 1 and the ice sheet in east antarctica ea shows a small mass gain 16 11 gt a 1 for a combined net change of 31 12 gt a 1 0 08 mm a 1 sle the contribution of the three ice sheets to sea level is 0 05 0 03 mm a 1 t he antarctic ice shelves show corresponding mass changes of 95 11 gt a 1 in wa and 142 10 gt a 1 in ea thinning at the margins of the greenland ice sheet and growth at higher elevations is an expected response to increasing temperatures and precipitation in a warming climate the marked thinnings in the pine island and thwaites glacier basins of wa and the totten glacier basin in ea are probably ice dynamic responses to long term climate change and perhaps past removal of their adjacent ice shelves the ice growth in the southern antarctic peninsula and parts of ea may be due to increasing precipitation during the last century

mineral microbe interactions in deep sea hydrothermal systems a challenge for raman spectroscopy in deep sea hydrothermal environments steep chemical and thermal gradients rapid and turbulent mixing and biologic processes produce a multitude of diverse mineral phases and foster the growth of a variety of chemosynthetic micro organisms many of these microbial species are associated with specific mineral phases and the interaction of mineral and microbial processes are of only recently recognized importance in several areas of hydrothermal research many submarine hydrothermal mineral phases form during kinetically limited reactions and are either metastable or are only thermodynamically stable under in situ conditions laser raman spectroscopy is well suited to mineral speciation measurements in the deep sea in many ways and sea going raman systems have been built and used to make a variety of in situ measurements however the full potential of this technique for hydrothermal science has yet to be realized in this focused review we summarize both the need for in situ mineral speciation measurements in hydrothermal research and the development of sea going raman systems to date we describe the rationale for further development of a small low cost sea going raman system optimized for mineral identification that incorporates a fluorescence minimizing design and we present three experimental applications that such a tool would enable