monsoon gyres of the northwest pacific influences of enso the mjo and the pacific japan pattern abstractan objective definition of monsoon gyres in the northwest pacific was developed in order to construct a gyre climatology over a 31 yr period 53 gyres were identified with a median formation location at 16 5 n 135 e more than 80 formed during july september more than half of gyres developed during el nino periods at a median location 1200 km farther to the east southeast than during la nina cyclonic winds at 850 hpa extended across a diameter of more than 4000 km with maximum tangential wind near the 1000 km radius a precipitation maximum extended westward for several thousand kilometers south of the gyre typhoons were most common north and east of the gyre centers more than 70 of gyres developed during large amplitude mjo events with a strong preference for real time multivariate mjo rmm phases 5 7 in boreal summer these phases contain circulation and convective anomalies that coincide most closely with those of the climatological monsoon trough gyres are most likely to form when

an observational search for carbonates on mars a search for carbonates and other salts exposed on the surface of mars was undertaken by observing areas of the surface in the 2 6 m to 4 2 m spectral region using the university of hawaii 2 2 m telescope at the mauna kea observatory hawaii observations of four mars areas syrtis major hellas arabia and an area northeast of hellas were made on the night of september 19 1986 the reflectance spectra for two partially overlapping areas show a weak absorption band in the 3 8 m to 3 9 m region which is in the spectral region where carbonate absorptions appear 3 8 m to 4 0 m the mars area of overlap contains syrtis planum the spectral feature from about 3 76 m to 3 95 m is clearly shortward of and broader than the calcium carbonate band about 3 9 m to 4 0 m and is at a slightly shorter wavelength position than magnesium carbonate magnesite bands about 3 8 m to 3 96 m as measured in this study positive identification of this band cannot be made by us at this time measurements for two other mars areas show no evidence of carbonate or other bands if the band is due to absorptions in the mars surface material spectrum and if it is due to carbonates then the results imply about 3 to 5 wt of a carbonate such as magnesite on average in the upper few millimeters of the mars surface material over the two areas where the weak spectral feature appears we can place an upper limit of 3 to 5 wt calcium carbonate and about 5 wt magnesite for all areas observed the interpretations are based on laboratory measurements of the reflectance spectra of calcite and magnesite and their mixtures with palagonite effects of thermal emission on the detection of carbonates were also explored for a wide range of temperatures thermal effects are not sufficient to mask the presence of calcite in the 3 to 5 wt range theoretical reasoning strongly supporting the presence of carbonates as a component of the mars surface is reviewed these and earlier observations do not rule out carbonates below the surface in other locations as small outcrops or in concentrations of less than 3 to 5 of the areas observed

the emergence of life from iron monosulphide bubbles at a submarine hydrothermal redox and ph front here we argue that life emerged on earth from a redox and ph front at c 4 2 ga this front occurred where hot c 150 c extremely reduced alkaline bisulphide bearing submarine seepage waters interfaced with the acid warm c 90 c iron bearing hadean ocean the low ph of the ocean was imparted by the ten bars of co 2 considered to dominate the hadean atmosphere hydrosphere disequilibrium between the two solutions was maintained by the spontaneous precipitation of a colloidal fes membrane iron monosulphide bubbles comprising this membrane were inflated by the hydrothermal solution upon sulphide mounds at the seepage sites our hypothesis is that the fes membrane laced with nickel acted as a semipermeable catalytic boundary between the two fluids encouraging synthesis of organic anions by hydrogenation and carboxylation of hydrothermal organic primers the ocean provided carbonate phosphate iron nickel and protons the hydrothermal solution was the source of ammonia acetate hs h 2 and tungsten as well as minor concentrations of organic sulphides and perhaps cyanide and acetaldehyde the mean redox potential eh across the membrane with the energy to drive synthesis would have approximated to 300 millivolts the generation of organic anions would have led to an increase in osmotic pressure within the fes bubbles thus osmotic pressure could take over from hydraulic pressure as the driving force for distension budding and reproduction of the bubbles condensation of the organic molecules to polymers particularly organic sulphides was driven by pyrophosphate hydrolysis regeneration of pyrophosphate from the monophosphate in the membrane was facilitated by protons contributed from the hadean ocean this was the first use by a metabolizing system of protonmotive force driven by natural aph which also would have amounted to c 300 millivolts protonmotive force is the universal energy transduction mechanism of life taken together with the redox potential across the membrane the total electrochemical and chemical energy available for protometabolism amounted to a continuous supply at more than half a volt the role of the iron sulphide membrane in keeping the two solutions separated was appropriated by the newly synthesized organic sulphide polymers this organic take over of the membrane material led to the miniaturization of the metabolizing system information systems to govern replication could have developed penecontemporaneously in this same milieu but iron sulphur and phosphate inorganic components of earliest life continued to be involved in metabolism

biomimetic properties of minerals and the search for life in the martian meteorite alh84001 the existence of extraterrestrial life was heralded by controversial claims made in 1996 that the martian meteorite alh84001 harbored relics of ancient microorganisms we review here the accumulated evidence for and against past extraterrestrial life in this martian meteorite the main pro life arguments the presence of polycyclic aromatic hydrocarbons magnetite crystals carbonate globules and structures resembling terrestrial life forms known as nanobacteria can be deemed ambiguous at best although these criteria are compatible with living processes each one of them can be explained by nonliving chemical processes by undergoing amorphous to crystalline transformations and binding to multiple substrates including other ions and simple organic compounds minerals especially those containing carbonate have been shown to display biomimetic properties producing forms that resemble bacteria this simple and down to earth explanation can account fully for the existence of mineral entities resembling put

the chemistry of geothermal waters in iceland ii mineral equilibria and independent variables controlling water compositions abstract the major element chemistry of icelandic geothermal waters is predictable provided two parameters are known this follows from an attainment of or a close approach to an overall chemical equilibrium in the geothermal systems at temperatures as low as 50 c it is considered that the geothermal system composition temperature and kinetic factors determine which alteration minerals form the system composition is not so much fixed by rock composition as by the rate of leaching of the various constituents from the fresh rock and the composition of inflowing water the water chemistry is determined by the system composition and the external variables acting on the system they include temperature and the mobility of chloride pressure which theoretically should be regarded as an external variable has insignificant effect on water compositions in the range 1 200 bars occurring in the geothermal systems

space time spectral analysis of the moist static energy budget equation abstractthe budget of column integrated moist static energy mse is examined in wavenumber frequency transforms of longitude time sections over the tropical belt cross spectra with satellite deri

high temperature life without photosynthesis as a model for mars discoveries in biology and developments in geochemistry over the past two decades have lead to a radical revision of concepts relating to the upper temperature at which life thrives the genetic relationships among all life on earth links between organic and inorganic compounds in geologic processes and the geochemical supply of metabolic energy it is now apparent that given a source of geochemical energy in the form of a mixture of compounds that is far from thermodynamic equilibrium microorganisms can take advantage of the energy and thrive without the need for photosynthesis as a means of primary productivity this means that life can exist in the subsurface of a planet such as mars without necessarily exhibiting a surface expression theoretical calculations quantify the geochemically provided metabolic energy available to hyperthermophilic organisms in submarine hydrothermal systems on the earth and help to explain the enormous biological productivity of these systems efforts to place these models in the context of the early earth reveal that substantial geochemical energy would have been available and that organic synthesis would have been thermodynamically favored as hydrothermal fluids mix with seawater

case studies of developing east pacific easterly waves this paper contains a study of developing east pacific easterly waves observed during the summer of 1991 with aircraft in situ and radar data and geosynchronous infrared satellite imagery the circulation and divergence profiles surface momentum and entropy fluxes as well as 700 mb and 975 mb saturated and actual equivalent potential temperatures were measured repeatedly for three disturbances that evolved into east pacific hurricanes as the disturbances develop the level of maximum updraught mass flux decreases which leads to increased convergence at low levels this process appears to be coupled to an increase in the mid level relative humidity which in turn suppresses the development of convective downdraughts comparison of the respective tendencies of convergence and surface friction to spin up and spin down a developing disturbance suggests that friction is unimportant in the early stages of development however as the surface circulation develops the two effects become comparable in magnitude if surface friction is deposited through a fairly deep layer of the troposphere the observations appear to rule out boundary layer ekman balance in these developing systems though more accurate observations of the eddy fluxes of absolute vorticity into such systems are needed to answer this question with certainty

synoptic scale disturbances near the equator abstract a spectral analysis of winds analyzed and initialized at the european centre for medium range weather forecasts reveals an abundance of power in the 850 mb meridional wind along the equator with periods near four days the power is mostly in the westward propagating component using high pass filtered data it is shown that the waves have westward phase and eastward group propagation relative to the mean wind the longest wavelengths are found over the pacific ocean while the shortest are found over the convectively variable regions of indonesia south america and africa mean phase speeds at 850 mb are positively correlated with the mean wind on the equator at 500 mb and below and negatively correlated with the mean wind above that level the effective advecting zonal wind of the disturbances seems to be the density weighted average of the lower troposphere the structure of the disturbances bears resemblance to the expected structure of an equatorially trapped mixed rossby gravity wave over t

interannual variations in mixed rossby gravity waves and their impacts on tropical cyclogenesis over the western north pacific abstract the present study investigates the transition from mixed rossby gravity mrg waves to tropical depression td type disturbances and its interannual variations over the western north pacific wnp using ecmwf high resolution data for the years of 1980 2001 as the equatorially trapped mrg waves propagate westward into the wnp the mrg waves transit to td type disturbances because of background flow change interannual variations in the transition of mrg waves are related to monsoon circulation change in response to tropical convective heating over the warm pool wp region when the wp is in a warm state convective heating is enhanced in the western part of the wnp and the monsoon trough retreats westward which induces a westward shift of the wave transition zone in contrast when the wp is in a relatively cold state the eastward penetration of convection and monsoon trough shifts the wave transition to the eastern part of the wnp the zonal wind convergence and shear in the monsoon trough

the nakhlite hydrothermal brine on mars abstract water is the basis of habitability and formation conditions of hydrous alteration minerals are key to temperature and chemical conditions of that water using new detailed observations on nakhlite martian meteorite alteration composition temperature and redox conditions of the water that formed the observed hydrous alteration can be determined through thermochemical modelling we show that the nakhlite parent rocks on mars encountered a co2 rich hydrothermal fluid at 150 t 200 c ph 6 8 with a water rock ratio w r 300 under these conditions fe rich carbonate was precipitated within brittle fractures as the fluid cooled to 50 c at ph 9 and w r of 6 fe rich phyllosilicate precipitated followed in turn by rapid precipitation of an amorphous gel it was enriched in the most soluble species e g k na of alkaline ph and similar to terrestrial i e not seawater influenced dilute brines in basaltic terrains on earth our results show that environments associated with this type of fluid were habitable unlike those associated with acid sulphate fluids considering the timing of the nakhlite alteration the most likely cause is impact generated hydrothermal alteration of the nakhlite pile at the margins of an impact crater the martian subsurface fluid forming phyllosilicates provided habitable temperatures and many of the nutrients required for life

cloud components of the intertropical convergence zone 1 this study explores the roles of different synoptic scale cloud systems in the making of the intertropical convergence zone itcz outgoing longwave radiation olr data are used to represent both the mean itcz and cloud systems an olr threshold of 205 w m 2 is used to distinguish daily mean deep convective clouds from nondeep clouds zonally moving synoptic scale cloud systems are identified through a cloud tracking method mean olr of the itcz is decomposed into five components westward and eastward moving synoptic scale deep convective clouds random nonpropagating deep convective clouds nondeep clouds and clear sky backgrounds hypothetical itczs each composed of one of the cloud components and the clear sky background are constructed and compared the largest synoptic scale cloud constituents of the itcz are nondeep clouds and deep clouds with no persistent tendency of zonal propagation each of the two comprises about 40 45 of total cloud signals in the itcz a weak itcz could exist solely because of westward propagating synoptic scale deep convective clouds in reality these westward propagating clouds contribute 25 40 of deep convective clouds and 10 20 of total clouds in the itcz contributions from eastward propagating synoptic scale clouds are much smaller 8 of the deep convective clouds and less than 5 of total clouds in the itcz an itcz without any zonally propagating synoptic scale deep convective clouds would be diffused in latitude the cloud compositions in the itcz and other tropical convective zones are compared their discrepancies indicate fundamental characteristics in large scale environments for the cloud components in different regions

horizontal and vertical structure of easterly waves in the pacific itcz abstract outgoing longwave radiation olr and low level wind fields in the atlantic and pacific intertropical convergence zone itcz are dominated by variability on synoptic time scales primarily associated with easterly waves during boreal summer and fall this study uses spectral filtering of observed olr data to capture the convective variability coupled to pacific easterly waves filtered olr is then used as an independent variable to isolate easterly wave structure in wind temperature and humidity fields from open ocean buoys radiosondes and gridded reanalysis products the analysis shows that while some pacific easterly waves originate in the atlantic most of the waves appear to form and strengthen within the pacific pacific easterly waves have wavelengths of 4200 5900 km westward phase speeds of 11 3 13 6 m s 1 and maximum meridional wind anomalies at about 600 hpa a warm moist boundary layer is observed ahead of the waves with moisture lofted quickly through the troposphere by deep co

lee vorticity production by large scale tropical mountain ranges part i eastern north pacific tropical cyclogenesis abstract numerical simulations using the penn state university ncar mm4 model are performed to examine a dry stably stratified zonal easterly flow past a large scale three dimensional mountain range in a rotating initially barotropic atmosphere upstream blocking by the mountain range diverts the flow primarily to the south and around the mountain conservation of potential vorticity results in the formation of a horizontal jet at low levels south of the mountain this jet is barotropically unstable and leads to a continuous production of synoptic scale vorticity maxima which separate from the mountain and propagate downstream simulations using an idealized mountain representative of the sierra madre in mexico imply that this mechanism may be an important contributor to tropical cyclogenesis in the eastern north pacific ocean the wave train produced in the simulations corresponds to waves with 3 7 day periods which have been identified observationally in the eastern north pacific region the sensi

retention of an atmosphere on early mars the presence of valley networks and indications of high erosion rates in ancient terrains on mars suggest that mars was warm and wet during heavy bombardment various processes that could occur on early mars were integrated into a self consistent model to determine what circumstances might lead to warm temperatures during and at the end of heavy bombardment included were weathering and burial of co2 as carbonates impact erosion sputtering and recycling of co2 back into the atmosphere by burial and heating the models suggest that despite losses from the atmosphere by weathering and impact erosion mars could retain a 0 5 to 1 bar atmosphere at the end of heavy bombardment partly because weathering temporarily sequesters co2 in the ground and protects it from impact erosion while the impact rate is declining and impact erosion is becoming less effective because of the low output of the early sun surface temperatures can be above freezing only for a very efficient greenhouse such as that suggested by forget and pierrehumbert 1997 with weak greenhouse models temperatures are below freezing throughout heavy bombardment and such a large amount of co2 is left in the atmosphere at the end of heavy bombardment that it is difficult to eliminate subsequently to arrive at the present surface inventory with strong greenhouse models temperatures are well above freezing during heavy bombardment and drop to close to freezing at the end of heavy bombardment at which time the atmosphere contains 0 5 to 1 bar of co2 this can be largely eliminated subsequently by sputtering and low temperature weathering such a model is consistent with the change in erosion rate and the declining rate of valley formation at the end of heavy bombardment conditions that favor warm temperatures at the end of heavy bombardment are an efficient greenhouse low weathering rates low impact erosion rates and a smaller fraction of heat lost by conduction as opposed to transport of lava to the surface

origin and history of hydrothermal fluids of the reykjanes and krafla geothermal fields iceland the reykjanes and krafla geothermal fields are both examples of active high temperature systems and show similar assemblages of alteration minerals but the fluid at reykjanes is dominantly sea water whereas that at krafla is meteoric oxygen isotope analyses of surface rock and of drill chip samples from different depths are presented together with results for the krafla fluid which is close to local precipitation 18o 11 9 d 86 8

westerly wind bursts and their relationship with intraseasonal variations and enso part ii energetics over the western and central pacific abstract the mechanism of synoptic scale eddy development in the generation of westerly wind bursts wwbs over the western central pacific and their relationship with the el nino southern oscillation enso and the madden julian oscillation mjo were examined in the wwb occurrences barotropic structures of equatorial eddy westerlies with cyclonic disturbances were found from the surface to the upper troposphere the dominant contributions to substantial eddy kinetic energy eke were the barotropic energy conversion kmke in the lower and middle tropospheres and the conversion from eddy available potential energy peke in the upper troposphere low frequency environmental westerlies centered near the equator preceded strong zonal convergence and meridional shear resulting in the substantial kmke the activation of synoptic convection also contributed to an increase in eke through peke these energies were redistributed to the lower equatorial troposphere through energy flux convergence gke the

structure and evolution of baroclinic waves as inferred from regression analysis abstract the structure of transient disturbances with periods shorter than a week is documented an the basis of one point regression maps and longitude height sections derived from the national meteorological center nmc operational analyses for nine winter seasons the reference time series for the regression coefficients is highpass filtered normalized 500 mb height at a grid point in the pacific stormtrack the field variables that were regreesed on the reference time series were not filtered the regression statistics yield quantitative estimates of the amplitudes of the high frequency fluctuations in the geopotential height temperature wind ageostrophic wind vorticity divergence vertical velocity and outgoing longwave radiation fields the observed high frequency fluctuations exhibit a vertical and meridional structure suggestive of baroclinic waves evolving through the mature phase of their life cycle most of the results are in qualitative agreement with previous studies but the ageostrop

an observational study of easterly waves over the eastern pacific in the northern summer using fgge data abstract fgge revel iii b data provided by the european centre for medium range weather forecasts and the outgoing longwave radiation data measured by satellites are used to investigate observationally relationships between deep cloud activity and large scale meteorological fields during the northern hemisphere summer may september of 1979 over the eastern pacific aside from the summer monsoon area over southern and eastern asia the eastern pacific is the area where strong deep convection frequently develops in the northern summer this is also one of the tropical ocean areas that have been least explored meteorologically a power spectral analysis using the maximum entropy method is made for the meridional wind component at 850 mb at various grid points in the analysis domain for each mouth from may through september the waves with a period of 4 6 days are not only stronger in july and august than those of other months but active in the regions of 100 130 w in the eastern pacific and 130 160 e i

satellite data analysis and numerical simulation of tropical cyclone formation 1 forecast of tropical cyclone tc formation has long been a great challenge owing to lack of reliable observations over vast open oceans recent satellite products provide a unique opportunity to reveal detailed atmospheric wave structures prior to tc formation using the quikscat surface wind and the tropical rainfall measurement mission microwave image data we document temporal and spatial structures of rossby wave trains induced by energy dispersion from a pre existing tc and easterly wave propagation characteristics prior to cyclogenesis in the western north pacific using a baroclinic model we further simulate cyclogenesis processes associated with the tc energy dispersion and easterly waves

exploring for a record of ancient martian life the immediate task facing exopaleontology is to define a strategy to explore mars for a fossil record during the decade long exploration program that lies ahead consideration of the quality of paleontological information preserved under different geological conditions is important if we are to develop a strategy with broad applicability the preservation of microbial fossils is strongly influenced by the physical chemical and biological factors of the environment which acting together determine the types of information that will be captured and retained in the rock record in detrital sedimentary systems preservation is favored by rapid burial in fine grained clay rich sediments in chemical sedimentary systems preservation is enhanced by rapid entombment in fine grained chemical precipitates for long term preservation host rocks must be composed of stable minerals that are resistant to chemical weathering and that form an impermeable matrix and closed chemical system to protect biosignatures from alteration during subsequent diagenesis or metamorphism in this context host rocks composed of highly ordered chemically stable mineral phases like silica e g cherts or phosphate e g phosphorites are especially favored such lithologies tend to have very long crustal residence times and along with carbonates and shales are the most common host rocks for the precambrian microfossil record on earth although we make the defensible assumption that mars was more like the earth early in its history clearly the geological and historical differences between the two planets are many such differences must be carefully considered when adapting an earth based strategy to mars

propagation and maintenance mechanism of the tc submonthly wave pattern and tc feedback in the western north pacific abstractpropagation and maintenance mechanisms of the tropical cyclone submonthly wave pattern in the western north pacific are explored the wave pattern exhibited an equivalent barotropic structure with maximum vorticity and kinetic energy in the lower troposphere and propagated northwestward in the philippine sea in the intraseasonal oscillation iso westerly phase and north northeastward near the east asian coast in the easterly phase the mean flow advection played a dominant role in the propagation in both phases barotropic energy conversion is the dominant process in maintaining the kinetic energy of the pattern the wave pattern tended to occur in the confluent zone between the monsoon trough and the anticyclonic ridge where the kinetic energy could be efficiently extracted from the westerly mean flow associated with the monsoon trough the individual circulation circuit embedded in the pattern was oriented northeast southwest east west to have optimal growth and propagation during the iso wes

hydrothermal formation of clay carbonate alteration assemblages in the nili fossae region of mars abstract the compact reconnaissance imaging spectrometer for mars crism has returned observations of the nili fossae region indicating the presence of mg carbonate in small

the origin and dispersion characteristics of the observed tropical summertime synoptic scale waves over the western pacific abstract the origin initiation and dispersion behavior of the observed summertime synoptic scale disturbances in the tropical western pacific are studied these westward propagating disturbances have the strongest growth rate over the region of 130 160 e off the equator the three dimensional wave activity flux associated with a wave packet in the vicinity of this region is computed in general wave activity is directed westward there is accumulation of activity flux which gives rise to the amplification of waves in the low levels such accumulation can be attributed to the convergence of both the mean flow and the intrinsic group velocity diabatic forcing also contributes to the growth of disturbances and is most important in the 500 600 hpa layer along the east west oriented storm tracks of the synoptic scale disturbances there are two different dynamical regimes west of 150 e enhanced convection is associated with increased specific humidity at the top of the planetary boundary layer an

experimental reproduction of the martian weathering profiles argues for a dense noachian co2 atmosphere abstract on mars mineral sequences have been detected and they are composed of a top layer of al rich clay minerals then al fe rich clay minerals and a bottom layer composed of mg fe rich clay minerals by analogy with earth such sequences are interpreted as weathering profiles formed by the interaction of acidic solutions in equilibrium with the atmosphere and the parent rock thus understanding of the aqueous solution composition leading to the above mineral description allows deciphering the atmosphere composition we designed an experimental column system with three levels containing powdered basaltic rock to test the influence of different acidic fluids on the mineralogical formation five solutions were used h 2 so 4 and hcl at ph 3 in equilibrium with n 2 atmosphere pure water in equilibrium with 0 1 and 1 atmospheric pressure co 2 leading to ph values of 3 9 and 4 4 respectively and a h 2 so 4 solution at ph 3 in equilibrium with 0 1 atmospheric pressure co 2 leading to a ph value of 2 98 the results obtained show that the content of al rich clay minerals and the evolution from al al fe to fe mg rich clay minerals formed are better reproduced with an originally high pco 2 hence we suggest that acidic alteration driven by a dense co 2 atmosphere reproduced better the observed martian weathering profiles the experiments involving co 2 led to the formation of carbonates their identification by near infrared nir detection methods is challenged because even the laboratory nir spectra acquired on the experimental products show that i the absorption bands related to carbonates are very weak and ii the strongest feature at 3 95 m is beyond the crism nir range such carbonate formation is consistent with the recent carbonate detection at a planetary scale in weathering profiles which goes toward that the weathering profiles could have been formed under a dense co 2 rich atmosphere as suggested also by climatic models

downstream development in the southern hemisphere monsoon during fgge wmonex abstract evidence is presented of a downstream development mechanism operating across the entire longitudinal span of the 1978 79 southern hemisphere monsoon observationally it is seen as progressive cyclonic and anticyclonic vorticity increases that develop eastward in the monsoon trough at a speed of approximately 5 m s 1 the process results in many tropical cyclone and tropical depression formations over northern australia and the south pacific it is shown that the downstream development process is generally consistent with linearized barotropic dynamics and that the southern hemisphere monsoon because of an intrinsic westerly basic state is a particularly suitable region for downstream events it is also shown that some apparent contradictions in previous observational studies can be rationalized by the theory the interactions between the regional components of the monsoon indonesian australian and south pacific sectors can also he better understood we further suggest that the process has i

volcaniclastic rocks of the reydarfjordur drill hole eastern iceland 2 alteration volcaniclastic rocks of basaltic to rhyolitic composition interlayered with basaltic to icelanditic lava flows in a 1918 m drill hole in eastern iceland are altered to zeolite and pumpellyite prehnite facies assemblages major alteration minerals are chlorites illite chlorite mixed minerals illites k feldspar laumontite quartz and sphene others include julgoldite and secondary allanite smectites as well as mordenite and heulandite are restricted to the upper 900 m epidote and minor pumpellyite prehnite wairakite and anhydrite are restricted to the core below 900 m the boundary between zeolite and prehnite pumpellyite facies is marked by the appearance of chlorite epidote quartz assemblages at around 900 m the typical paragenesis prehnite pumpellyite epidote chlorite occurs near the base of the drill hole at 1855 m textures indicate generally prograde metamorphic conditions the broad compositional spectrum ranging from basalt to rhyolite abundance of vitric fragments and high initial porosity and permeability of the volcaniclastic rocks were major factors governing alteration the site of growth crystal shard vesicle pore and vein of a secondary phase strongly influences composition habit amount paragenesis and time of crystallization for example sphene and to a lesser degree epidote are less rich in fe and better crystallized in plagioclase than in the adjacent matrix the different mineral assemblages developed within plagioclase crystals through the section most clearly reflect the metamorphic changes the abundance of vitric rhyolitic clasts shards and pumice favored k al si enriched fluids from which phases like illite and adularia crystallized these phases were not found in interlayered basalt flows mehegan et al this issue low ca activity is also indicated by the occurrence of wairakite and pumpellyite rather than prehnite which is common in the basalts secular changes during metamorphism in pore fluid composition are shown by zonations in mineral compositions for example the depletion of epidote and juldoldite pumpellyite in fe with time appears to reflect decreasing o2 bulk rock chemical changes are more intense in the volcaniclastic rocks compared to the basalt lavas h2o fe3 fe2 and in part co2 values are higher in the upper part of the hole reflecting the higher porosity and glass content of the clastic rocks they decrease markedly downhole approaching values of the lava flows due to more pervasive metamorphic alteration and thus similar mineral assemblages and physical properties

synthetic seismogram based deterministic seismic zoning for the hungarian part of the pannonian basin deterministic seismic hazard computations have been done for the hungarian part of the pannonian basin within the framework of a cooperation of five countries synthetic seismograms have been computed by the modal summation method up to 1 hz in order to determine the expected maximum displacement dmax velocity vmax and the design ground acceleration dga on a 0 2 0 2 grid dga values have been estimated from the seismograms by using the standard this investigation justified the suspicion that a considerable part of seismic hazard of hungary comes from the seismogenic zones of the neighbouring countries the highest dga reaches a value as high as 0 14 g which corresponds approximately to the viii intensity degree in the msk 64 scale among the six largest cities of hungary three art particularly subject to a high seismic risk greater acceleration values have been found for the cities of szeged and debrecen than was expected before this study

rossby wave energy dispersion from tropical cyclone in zonal basic flows this study investigates tropical cyclone energy dispersion under horizontally sheared flows using a nonlinear barotropic model in addition to common patterns unusual features of rossby wave trains are also found in flows with constant vorticity and vorticity gradients in terms of the direction of the energy dispersion the wave train can rotate clockwise and elongate southwestward under anticyclonic circulation ash which contributes to the reenhancement of the tropical cyclone tc the wave train even splits into two obvious wavelike trains in flows with a southward vorticity gradient wsh energy dispersed from tcs varies over time and variations in the intensity of the wave train components typically occur in two stages wave activity flux diagnosis and ray tracing calculations are extended to the frame that moves along with the tc to reveal the concrete progress of wave propagation the direction of the wave activity flux is primarily determined by the combination of the basic flow and the tc velocity along the flux the distribution of pseudomomentum effectively illustrates the development of wave trains particularly the rotation and split of wave propagation ray tracing involves the quantitative tracing of wave features along rays which effectively coincide with the wave train regimes flows of a constant shear parabolic meridional variation produce linear nonlinear wave number variations for the split wave trains the real and complex wave number waves move along divergent trajectories and are responsible for different energy dispersion ducts

mixed rossby gravity waves and western pacific tropical cyclogenesis part i synoptic evolution abstract a large amplitude mixed rossby gravity wave packet is identified in the western pacific using 6 10 day bandpass filtered winds individual disturbances of 2300 3000 km wavelength propagated westward as the packet moved slowly eastward the packet first appeared and subsequently amplified within a region of active convection associated with the madden julian oscillation mjo which was isolated by low pass filtered outgoing longwave radiation the packet lasted about 5 weeks then rapidly dispersed as the active mjo moved away from it to the east west of 150 e individual disturbances within the packet turned northwestward away from the equator indicating an apparent transition from mixed rossby gravity waves to off equatorial tropical depression td type disturbances cyclones filled with cloud and anticyclones cleared during the transition nevertheless convective structure consistent with mixed rossby gravity waves remained outside the circulation centers and three tropical cyclones for

organic synthesis during fluid mixing in hydrothermal systems hydrothermal circulation can lead to fluid mixing on any planet with liquid water and a source of heat aqueous fluids with differing compositions especially different oxidation states are likely to be far from thermodynamic equilibrium when they mix and provide a source of free energy that can drive organic synthesis from co 2 and h 2 and or supply a source of geochemical energy to chemolithoautotrophic organisms results are presented that quantify the potential for organic synthesis during unbuffered fluid mixing in present submarine hydrothermal svstems as well as hypothetical systems that may have existed on the early earth and mars dissolved hydrogen present in submarine hydrothermal fluids owing to the high temperature reduction of h 2 o as seawater reacts with oceanic crustal rocks provides the reduction potential and the thermodynamic drive for organic synthesis from co 2 or bicarbonate as hydrothermal fluids mix with seawater the potential for organic synthesis is a strong function of the h 2 content of the hydrothermal fluid which is in turn a function of the prevailing oxidation state controlled by the composition of the rock that hosts the hydrothermal system hydrothermal fluids with initial oxidation states at or below those set by the fayalite magnetite quartz mineral assemblage show the greatest potential for driving organic synthesis these calculations show that it is thermodynamically possible for 100 of the carbon in the mixed fluid to be reduced to a mixture of carboxylic acids alcohols and ketones in the range 250 50 c as cold seawater mixes with the hydrothermal fluid as the temperature drops larger organic molecules are favored which implies that fluid mixing could drive the geochemical equivalent of a metaholic system this enormous reduction potential probably drives a large portion of the primary productivity around present seafloor hydrothermal vents and would have been present in hydrothermal systems on the early earth or mars the single largest control on the potential for organic synthesis is the composition of the rock that hosts the hydrothermal system

on large scale circulations in convecting atmospheres the dominant thinking about the interaction between large scale atmospheric circulations and moist convection holds that convection acts as a heat source for the large scale circulations while the latter supply water vapour to the convection we show that this idea has led to fundamental misconceptions about this interaction and offer an alternative paradigm based on the idea that convection is nearly in statistical equilibrium with its environment according to the alternative paradigm the vertical temperature profile itself rather than the heating is controlled by the convection which ties the temperature directly to the subcloud layer entropy the understanding of large scale circulations in convecting atmospheres can therefore be regarded as a problem of understanding the distribution in space and time of the subcloud layer entropy we show that the subcloud layer entropy is controlled by the sea surface temperature the surface wind speed and the large scale vertical velocity in the convecting layer and demonstrate how the recognition of this control leads to a simple physically consistent view of large scale flows ranging from the hadley and walker circulations to the 30 50 day oscillation in particular we argue that the direct effect of convection on large scale circulations is to reduce by roughly an order of magnitude the effective static stability felt by such circulations and to damp all of them

a geochemical model for the formation of hydrothermal carbonates on mars it is often argued that substantially more carbon dioxide and water were degassed from the martian interior than can be found at present in the atmosphere polar caps and regolith calculations have shown that atmospheric escape cannot account for all of the missing volatiles suggestions that carbon dioxide is stored as marine or lacustrine deposits are challenged by earth based and spacecraft remote sensing data moreover recent modelling of the martian atmosphere suggests that rainfall or open bodies of water are in any case unlikely to have persisted for extended periods of time hydrothermal carbonates therefore provide a possible solution to this dilemma using an accessible terrestrial system iceland as a guide to the underlying processes and a host rock composition inferred from the least altered martian meteorite we present a geochemical model for the formation of carbonates in possible martian hydrothermal systems our results suggest that an extensive reservoir of carbonate minerals equivalent to an atmospheric pressure of carbon dioxide of at least one bar could have been sequestered beneath the surface by widespread hydrothermal activity in the martian past

effect of enso and the mjo on western north pacific tropical cyclones prior work has suggested that rossby wave accumulation in the lower troposphere may be an important mechanism for the development of synoptic scale disturbances in the western north pacific in northern summer this work examines the intraseasonal and interannual variability of wave accumulation by computing the barotropic wave activity flux divergence at 850 hpa for different phases of the madden julian oscillation mjo and el nino southern oscillation enso indirectly and without ruling out other influences the results suggest a physical mechanism behind previously identified relationships between tropical cyclogenesis statistics and these two modes of variability mjo and enso

modeling of major martian magnetic anomalies further evidence for polar reorientations during the noachian abstract maps of the vector components of the mars crustal magnetic field are constructed at the mapping altitude 360 to 410 km using a selected set of data obtained with the mars global surveyor magnetometer during 2780 orbits of the planet in 1999 forward modeling calculations are then applied to six relatively strong and isolated dominantly dipolar magnetic anomalies for the primary purpose of estimating bulk directions of magnetization assuming that the magnetizing field was a dipolar core dynamo field centered in the planet paleomagnetic pole positions are calculated for the six primary source bodies together with that for a seventh anomaly analyzed earlier in agreement with several previous studies it is found that six of the seven pole positions are clustered in what is now the northern lowlands in a region centered northwest of olympus mons mean pole position 34 10 n 202 58 e assuming that the dynamo dipole moment vector was approximately parallel to the rotation axis the modeling results therefore suggest a major reorientation of mars relative to its rotation axis after magnetization was acquired such a reorientation may have been stimulated by internal mass redistributions associated with the formation of the northern lowlands and tharsis for example a comparison of the mean paleo magnetic equator to the global distribution of crustal fields shows that magnetic anomalies tend to occur at low paleolatitudes the same appears to be true for the noachian aged valley networks which exhibit a broad spatial correlation with the magnetic anomalies a possible interpretation is that the formation of magnetic anomalies and the valley networks was favored in the tropics where melting of water ice and snow was a stronger source of both surface valley erosion and groundwater recharge during the earliest history of the planet this would be consistent with models in which hydrothermal alteration of crustal rocks played a role in producing the unusually strong martian magnetic anomalies

paleomagnetic evidence of a low temperature origin of carbonate in the martian meteorite alh84001 indirect evidence for life on mars has been reported from the study of meteorite alh84001 the formation temperature of the carbonates is controversial some estimates suggest 20 to 80 c whereas others exceed 650 c paleomagnetism can be used to distinguish between these possibilities because heating can remagnetize ferrimagnetic minerals study of two adjacent pyroxene grains from the crushed zone of alh84001 shows that each possesses a stable natural remanent magnetization nrm implying that mars had a substantial magnetic field when the grains cooled however nrm directions from these particles differ implying that the meteorite has not been heated significantly since the formation of the internal crushed zone about 4 billion years ago the carbonate globules postdate this brecciation and thus formed at low temperatures

experimental hydrothermal alteration of a martian analog basalt implications for martian meteorites a number of martian meteorite samples contain secondary alteration minerals such as ca mg fe carbonates fe oxides and clay minerals these mineral assemblages hint at hydrothermal processes occurring in the martian crust but the alteration conditions are poorly constrained this study presents the results of experiments that examined the alteration of a high fe basalt by co2 saturated aqueous fluids at 23 and 75 c and by mixed h2o co2 vapors at 200 and 400 c and water rock ratios of 1 1 and 1 10 results indicate that observable alteration of the basalt takes place after runs of only seven days this alteration includes mobilization of silica into phases such as opal ct and quartz as well as the formation of carbonates oxides and at some conditions zeolites and hydrous silicates the degree of alteration increases with run temperature and in high temperature vapor experiments with increasing water content of the vapor the degree of alteration and the mineralogy observed in the martian meteorites suggests that none of these samples were exposed to aqueous fluids for long periods of time nakhla and lafayette probably interacted with water for relatively brief periods of time if so silica may have been leached from the parent rocks by the altering fluids allan hills 84001 shows possible evidence for very limited interaction with an aqueous fluid but the overall slight degree of alteration described for this meteorite strongly suggests that it never interacted extensively or at high temperature with any water bearing fluid elephant moraine a79001 may not have been altered by aqueous fluids at all the results of this study best support models wherein the meteorite parent rocks were wetted intermittently or for brief periods of time rather than models that invoke long term reaction with large volumes of water our experiments studied alteration of a high fe basalt by dilute co2 saturated aqueous solutions at 23 and 75 c and by mixed h2o co2 vapors at 200 and 400 c the results suggest that alteration of the parent rock takes place even after very short reaction times of seven days all experiments produced carbonate minerals including calcite and in some cases magnesite siderite and ankerite a free silica phase either opal quartz or hydrated silica formed in most experiments more altered experiments also contained minerals such as zeolites and hydrous phyllosilicates clay minerals were not observed to form in any experiments in aqueous fluids higher temperature corresponded with a higher degree of alteration whereas changing fluid composition had no observable effect in high temperature vapors the degree of alteration was controlled by temperature and the proportion of h2o to co2 with water rock ratio also playing a role in transport of silica application of these results to martian meteorites that contain secondary alteration minerals suggests that none of the martian rocks underwent extensive interaction with aqueous fluids nakhla and lafayette contain clay minerals which suggests that they interacted with water to some extent possibly at elevated temperatures although alh84001 shows possible evidence of very limited interaction with aqueous fluids eeta79001 does not these results support models for the alteration of these meteorites that do not invoke long term interaction with water or reaction with large volumes of water except for some models for alteration of alh84001 this conclusion agrees with most of the literature on alteration of martian meteorites

the influence of wave trains in mid high latitudes on persistent heavy rain during the first rainy season over south china based on daily precipitation data from the chinese meteorological administration and reanalysis data from the national centers for environmental prediction department of energy the character of low frequency precipitation variability during the first rainy season april june over south china and its corresponding atmospheric circulations in the mid high latitudes are investigated the results show that the precipitation anomalies during this period exhibit obvious quasi biweekly oscillation qbwo features with a period of 8 24 days the influence of wave trains in the mid high latitudes to low frequency persistent heavy rain event phr lf event the 8 24 day filtered precipitation larger than one standard deviation of filtered time series and persisting at least three days over south china is further discussed during the first rainy season over south china there are two low frequency wave trains in the mid high latitudes associated with the phr lf event the wave train crossing the eurasian continent and the wave train along the subtropical westerly jet analysis of wave activity flux indicates that the wave energy disperses toward eastern china along these two low frequency wave trains from north to south and from west to east and then propagates downward over south china accordingly the disturbance of the relative vorticity of the cyclonic anomalies over eastern china is strengthened which enhances the meridional gradient of relative vorticity owing to the transport of low frequency relative vorticity and geostrophic vorticity by meridional wind the ascending motion over south china intensifies and lasts for a long time triggering a phr lf event in addition the tropical system is also a key factor to phr lf event the qbwo of the convection over the south china sea provide moisture for phr lf events maintaining persistent rainfall and vertical ascending motion over south china

alteration mineralogy of home plate and columbia hills formation conditions in context to impact volcanism and fluvial activity the mars exploration rover spirit investigated the igneous and alteration mineralogy and chemistry of home plate and its surrounding deposits here we focus on using thermochemical modeling to understand the secondary alteration mineralogy at the home plate outcrop and surrounding columbia hills region in gusev crater at high temperatures 300 c magnetite occurs at very high w r ratios but the alteration assemblage is dominated by chlorite and serpentine over most of the w r range quartz epidote and typical high t phases such as feldspar pyroxene and garnet occur at low w r at epithermal temperatures 150 c hematite occurs at very high w r a range of phyllosilicates including kaolinite nontronite chlorite and serpentine are precipitated at specific w r amphibole with garnet feldspar and pyroxene occur at low w r if the co2 content of the system is high the assemblage is dominated by carbonate with increasing amounts of an sio2 phase kaolinite carpholite and chlorite with lower w r at temperatures of hydrous weathering 13 c the oxide phase is goethite silicates are chlorite nontronite and talc plus an sio2 phase in the presence of co2 the mineral assemblage at high w r remains the same and only at low w r i e with increasing salinity carbonate precipitates the geochemical gradients observed at home plate are attributed to short lived initially high 300 c temperature but fast cooling events which are in agreement with our models and our interpretation of a multistage alteration scenario of home plate and gusev in general alteration at various temperatures and during different geological processes within gusev crater has two effects both of which increase the habitability of the local environment precipitation of hydrous sheet silicates and formation of a brine which might contain elements essential for life in diluted easily accessible form

potential vorticity modeling of the itcz and the hadley circulation abstract a simple zonally symmetric balanced model of the hadley circulation is presented the model is based on potential vorticity arguments and consists of a predictive equation for the potential pseudodensity and an invertibility principle to diagnose the associated balanced wind and mass fields when the theory is formulated in the potential latitude coordinate the meridional advection is implicit in the coordinate transformation which makes the prediction equation for potential pseudodensity analytically solvable for convective heating patterns that simulate the itcz the model produces upper and lower tropospheric potential vorticity anomalies of opposite sign the associated winds are easterly at low levels and westerly aloft except between the equator and the itcz where there are low level westerlies and upper level easterlies since the potential vorticity anomalies develop within a background state that has potential vorticity increasing to the north reversed poleward gradients of potenti

the superposition of eastward and westward rossby waves in response to localized forcing abstractrossby waves are a principal form of atmospheric communication between disparate parts of the climate system these planetary waves are typically excited by diabatic or orographic forcing and can be subject to considerable downstream modification because of differences in wave properties including vertical structure phase speed and group velocity rossby waves exhibit a wide range of behaviors this study demonstrates the combined effects of eastward propagating stationary barotropic rossby waves and westward propagating very low zonal wavenumber stationary barotropic rossby waves on the atmospheric response to wintertime el nino convective forcing over the tropical pacific experiments are conducted using the community atmosphere model version 4 0 in which both diabatic forcing over the pacific and localized relaxation outside the forcing region are applied the localized relaxation is used to dampen rossby wave propagation to either the west or east of the forcing region and isolate the al

experimental epithermal alteration of synthetic los angeles meteorite implications for the origin of martian soils and identification of hydrothermal sites on mars 1 the dissolution behavior and secondary minerals generated by experimental alteration of a synthetic los angeles basaltic shergottite la were evaluated at epithermal 75 c conditions starting ph values of 1 1 and 3 6 and water rock ratios ranging from 100 to 2000 were studied using flow through and batch reactor experimental apparatus dissolution of plagioclase dominates effluent solution chemistry under all experimental conditions little mg is released to solution because nearly 100 of the mg in unaltered la is contained in pyroxene m1 sites which are relatively resistant to dissolution secondary minerals generated include siliceous residue amorphous sio2 lepidocrocite and ferrihydrite anhydrite alunogen rhomboclase ferrinatrite halite and unidentified ca and na sulfates the dominance of alteration products of plagioclase suggests that la type basalts have not contributed significantly to the martian soils the search for hydrothermal sites by remote sensing may be hampered by the general similarity of the alteration products found in the near surface epithermal environment to those thought to exist in martian soils sulfates iron oxyhydroxides amorphous silica however the unique chemical composition of secondary products formed by la alteration may make detection of recent hydrothermal alteration of evolved basaltic rocks more straightforward in addition alteration in terrestrial epithermal environments associated with mafic to intermediate volcanic rocks generally produces abundant sulfides and kaolinite two potentially unique mineral phases which might also indicate the presence of active or extinct hydrothermal systems

barotropic aspects of itcz breakdown abstract in satellite images the itcz intertropical convergence zone is sometimes observed to undulate and break down into a series of tropical disturbances tropical cyclones may later develop within these disturbances and move into higher latitudes allowing the itcz to reform it has been proposed that itcz breakdown results from a convectively modified form of combined barotropic and baroclinic instability of the mean flow an unstable mean flow can be produced by itcz convection in just a couple of days in this sense the itcz produces favorable conditions for its own instability and breakdown in this study a nonlinear shallow water model on the sphere is used to simulate barotropic aspects of itcz breakdown in the shallow water model the itcz is simulated by a prescribed zonally elongated mass sink near the equator the mass sink produces a cyclonic potential vorticity pv anomaly that has a reversed meridional pv gradient on its poleward side according to the ripa theorem a flow that has a

search for signs of ancient life on mars expectations from hydromagnesite microbialites salda lake turkey the 9white rock9 constituting a portion of what may be a lacustrine sedimentary sequence near the margin of a crater c 90 km across in sabaea terra mars measures 18 15 km 180 540 m high it is re interpreted as a lens of magnesium carbonate precipitated where ground waters seeped into an ancient evaporating crater lake were life to have emerged on mars as seems feasible then the 9white rock9 might be expected to comprise a complex of stromatolitic mounds salda golu lake in turkey is taken as an analogue this enclosed lake is nearly surrounded and underlain by partially serpentinized harzburgite hydromagnesite stromatolites microbialites up to 7 m high coalesce to form a group of small islands 200 m across the microbialites are seen to be growing near the mouth of the usually dry salda river in the southwestern sector smaller developments of hydromagnesite encircle the lake and image processing of satellite data reveals a second extensive zone beneath the lake surface over a delta in the southeast individual columns a few centimetres high constitute bulbous mounds which are about 2 m in diameter these columns terminate in domes a centimetre or so across the domes are often annulated and are covered with a green biofilm a few millimetres thick comprised of cyanobactrial filaments the columns consist of alternating fine and coarse hydromagnesite layers differentiated on a millimetric scale the coarser layers near the surface still contain traces of the biofilm fossil microbialites were also discovered in the friable hydromagnesite cliffs shoreward of the main developments though the structures of the individual microbes have not survived instead the vestiges of microbialites are easily recognized and delineated by their coarse grain size and high porosity annular structures on their upper surfaces can be seen in places the intervening and overlying material also comprised of hydromagnesite is a semi lithified mud bulbous megascopic structures separated by finer grained magnesium carbonate mudstone within strata in the 9white rock9 would be strong evidence of a photosynthetic microbial genesis another deposit of white rock on the western margin of juventae chasma could have a similar origin

hydrothermal hydration of martian crust illustration via geochemical model calculations if hydrothermal systems existed on mars hydration of crustal rocks may have had the potential to affect the water budget of the planet we have conducted geochemical model calculations to investigate the relative roles of host rock composition temperature water to rock ratio and initial fluid oxygen fugacity on the mineralogy of hydrothermal alteration assemblages as well as the effectiveness of alteration to store water in the crust as hydrous minerals in order to place calculations for mars in perspective models of hydrothermal alteration of three genetically related icelandic volcanics a basalt andesite and rhyolite are presented together with results for compositions based on snc meteorite samples shergotty and chassigny temperatures from 150 c to 250 c water to rock ratios from 0 1 to 1000 and two initial fluid oxygen fugacities are considered in the models model results for water to rock ratios less than 10 are emphasized because they are likely to be more applicable to mars in accord with studies of low grade alteration of terrestrial rocks we find that the major controls on hydrous mineral production are host rock composition and temperature over the range of conditions considered the alteration of shergotty shows the greatest potential for storing water as hydrous minerals and the alteration of icelandic rhyolite has the lowest potential

the biological potential of mars the early earth and europa the potential biomass that could have existed on mars is constrained by the total amount of energy available to construct it from an inventory of the available geochemical sources of energy we estimate that from the time of the onset of the visible geologic record 4 b y ago to the present as much as 20 g cm 2 of biota could have been created this is the same amount that could have been constructed on the early earth in only 100 million years this indicates that there likely was sufficient energy available to support an origin of life on mars but not sufficient energy to create a ubiquitous and lush biosphere similar calculations for europa suggest that even less geochemical energy would have been available there

cross equatorial influences of submonthly scale southerly surges over the eastern indian ocean during southern hemisphere winter 1 lower tropospheric southerly surges occurring at submonthly timescales over the eastern indian ocean eio during southern hemisphere sh winter are extratropical tropical interaction phenomena involving various processes this study examined the physical mechanism driving equatorial wave disturbances associated with surge induced cross equatorial flow over the eio japanese 25 year reanalysis jra25 and tropical rainfall measuring mission satellite trmm 3b42 data products from june to august for the 7 years from 1998 to 2004 were analyzed composite analyses of low level wind and vorticity fields reveal that an equatorial clockwise gyre develops just after cross equatorial penetration of southerly surge winds this gyre is interpreted as an equatorially trapped rossby wave that develops asymmetrically around the equator in response to surge induced cross equatorial flow eddy vorticity budget analysis demonstrates the dynamic role of the southerly surge in the genesis of the equatorial clockwise gyre the result indicates that an injection of negative absolute vorticity into the equatorial tropics due to both advective and convergent processes associated with the surge winds is primarily responsible for the gyre genesis cross equatorial advection of basic state absolute vorticity by the surge eddy winds and vortex stretching by surge wind convergence are most effective in spinning up the equatorial clockwise gyre wave activity flux analysis further emphasizes that rossby wave energy propagation from the sh extratropics into the equatorial eio region is caused by the southerly surge these dynamic diagnostics suggest that the southerly surge plays a lateral forcing role in exciting the equatorial wave disturbance over the eio composite analyses of moisture flux and precipitation anomalies characterize the equatorial clockwise gyre as a convectively coupled equatorial rossby wave enhanced cross equatorial moisture transport due to the southerly surge appears to be linked to precipitation along the west coast of the southern indo china peninsula a case study of the southerly surge event during august 2000 illustrates the formation of the equatorial clockwise gyre and its convectively coupled equatorial rossby wave signature

mars a water rich planet abstract mars had outgassed at least 0 5 to 1 km of water 10 to 20 bar of co2 and 0 1 to 0 3 bar of n2 the volatiles that have been retained are mostly in the cratered uplands terrain softening fretted channels debris flows and closed depressions indicate that at least the upper 2 km of the cratered uplands at high latitudes 30 contain ice in amounts that exceed the porosity estimated to be 10 20 theoretical studies and lack of these features in the cratered uplands at low latitudes suggest that the upper 1 km of the uplands at low latitudes is ice poor however valley networks indicate that water was present near the surface early in the planet s history although in amounts smaller than at high latitudes the entire upper 1 km planetwide is estimated to have contained 75 125 m of water at the end of heavy bombardment the largest sink for water is the megaregolith below 1 km episodic eruption of water from the deep megaregolith cut many of the large outflow channels from the volume of water needed to cut the circum chryse channels and assuming uniform planetwide distribution of water the deep megaregolith is estimated to have contained at least 350 m of water at the end of heavy bombardment thereby giving a total minimum inventory of 424 475 m planetwide most of the water lost from the low latitude uplands by diffusion and in cutting the valley networks is now believed to be in the polar layered terrains most of the water involved in cutting the outflow channels is in the low lying northern plains where a variety of features that have been attributed to ground ice is present a large fraction of the planet s surface has been overplated with water poor volcanics of which we have samples in the snc meteorites the younger volcanics have reacted extensively with the old volatile rich basement some of the co2 and n2 outgassed was lost during heavy bombardment by impact erosion of the atmosphere and other processes the remaining was fixed carbonates and folded deep into the megaregolith during heavy bombardment

multi scale interactions of equatorial waves associated with tropical cyclogenesis over the western north pacific the tropical cyclone tc centric approach developed in previous studies tends to overemphasize the direct impact of tropical waves and underestimates their large scale modulation of western north pacific wnp tropical cyclogenesis tcg to overcome these limitations this study proposes a new approach based on empirical orthogonal function analyses to re examine associations of multiple waves including the madden julian oscillation mjo quasi biweekly oscillation qbwo convective equatorial rossby er waves and synoptic scale waves ssws with wnp tcg events there is a close association between wnp tcg events total of 273 tcs in this study and ssws 64 mjo 68 qbwo 64 and er 65 waves these suggest that ssw is critical for many tcg events and all of these intra seasonal waves significantly modulate tcg events a majority of tcs 79 were found to be related to more than one wave type indicating an important role for a combination of dynamic and thermodynamic conditions associated with multiple waves in tcg events further analyses show that ssw activity is strongly modulated by the mjo and er waves while the qbwo has no significant impact on ssws during convectively active mjo and er phases stronger ssw trains with more distinct southeast northwestward aligned structures can be found compared to convectively inactive phases similar intra seasonal modulation of the transition from the mixed rossby gravity waves from the equatorial central pacific to the ssw trains over the wnp by the three waves is noted with such transitions largely favored during convectively active mjo and er phases

the fate of early mars lost water the role of serpentinization the fate of water which was present on early mars remains enigmatic we propose a simple model based on serpentinization a hydrothermal alteration process which may produce magnetite and store water our model invokes serpentinization during about 500 to 800 myr while a dynamo is active which may have continued after the formation of the crustal dichotomy we show that the present magnetic field measured by mgs in the southern hemisphere is consistent with a 500 m thick global equivalent layer of water trapped in serpentine serpentinization results in the release of h 2 the released h atoms are lost to space through thermal escape increasing the d h ratio in water reservoirs exchanging with atmosphere we show that the value of the d h ratio in the present atmosphere 5 is consistent with the serpentinization of a 500 m thick water gel we reassess the role of non thermal escape in removing water from the planet by considering an updated solar wind ionosphere interaction representation we show that the contribution of oxygen escape to h isotopic fractionation is negligible our results suggest that significant amounts of water up to a 330 1030 m thick gel present at the surface during the noachian similar to the quantity inferred from the morphological analysis of valley networks could be stored today in subsurface serpentine 1 the study like earth mars has been endowed with large amounts of water during accretion equivalent to the content of several terrestrial oceans corresponding to a several 10 km thick global equivalent layer the present inventory of observable water on mars mainly within the polar caps is quite smaller in the range from 20 30 m the mega regolith capacity is large with up to 500 gel m potentially trapped in the cryosphere and hypothetically several additional hundreds of meters up to 500 m of ground water surviving at depth below the cryosphere 1 a 500 m thick gel is generally assumed to be required to explain the formation of outflow channels 2 and most of this water could be trapped today as water ice and possibly deep liquid water in the subsurface and also possibly under the form of hydrated minerals

observation of 3 6 day meridional wind oscillations over the tropical pacific 1973 1992 horizontal structure and propagation abstract twenty years of rawinsonde data 1973 1992 were examined in conjunction with european centre for medium range weather forecasts ecmwf analyses and outgoing longwave radiation olr in 1980 1989 to determine the horizontal structure propagation and convective coupling of 3 6 day meridional wind oscillations over the tropical pacific wave properties from ecmwf data determined by lag correlation with respect to rawinsonde or ecmwf principal components were consistent with what could be determined from the sparse rawinsonde network alone gridded analyses allowed a clearer distinction between equatorially trapped rossby gravity waves rgw and off equatorial tropical depression td disturbances so that the contrasting properties of these waves including their seasonal and interannual variation could be studied in better detail significant correlations with olr were found increasing in magnitude from eastern to western pacific the apparent group propagation of disturbances was equator

thermal emission spectra of mars 5 4 10 5 μm evidence for sulfates carbonates and hydrates we have obtained spectra of the thermal emission from mars in the 5 4 10 5 m wavelength domain at a resolving power of about 60 from the kuiper airborne observatory spectra were obtained for several large spots on mars whose ground temperatures and air masses through the martian atmosphere differed significantly these data were taken at two times during the flight by taking the ratio of the spectral flux from one spot to that of a second spot we obtained results that were independent of uncertainties in the instrument s spectral response and the transmission of the earth s atmosphere these data as well as spectral fluxes of single spots based using the star tau as a calibration standard show a number of emission and absorption features they are present in sets of spectra taken at two different times some of the absorption features are due to gaseous co2 in the martian atmosphere the remainder of the absorption and emission features are due to minerals present in the airborne dust and on the surface comparison of the strength of features seen at similar times but with three different air masses and ground temperatures suggests that the emission features arise primarily from surface emissivity spectral variations and that the absorption features arise from components of the atmosphere based on comparisons of the observed features with laboratory data for a broad ensemble of minerals spectra of other solar system bodies and relevant compositional information about mars we have made the following tentative identifications of the observed features emission features at 7 8 and 9 7 m are attributed to surface silicates an emission feature at 6 1 m is attributed to a molecular water component of the surface material an absorption band at 8 7 m as well as possibly one at 9 8 m is ascribed to sulfate or bisulfate anions probably located in a distorted crystalline site and an absorption band at 6 7 m is attributed to carbonate or bicarbonate anions located in a distorted crystalline site although we cannot totally rule out a nitrate origin for this feature we have simulated these spectra with radiative transfer programs for the atmosphere and surface these simulations indicate that the sulfate and carbonate bearing minerals are contained in the same particles of the airborne dust as the dominant silicate minerals that the dust optical depth was about 0 6 at a reference wavelength of 0 3 m over the area of the observed spots and that sulfates and carbonates constitute about 10 15 and 1 3 by volume of the airborne dust respectively these results imply that minerals formed by weathering processes represent major reservoirs of volatile species on current mars

sources of nutrients and energy for a deep biosphere on mars hydrothermal vents appear to be the tip of the subsurface biosphere in the ocean crust the primary prducers in this biosphere are prokaryotes that tolerate a wide variety of physical and chemical conditions and are versatile in their use of inorganic compounds to drive metabolism a synthesis of chemical and mineralogical data from martian meteorites and measurements of the martian surface suggest that conditions similar to those that make life possible in earth s oceanic crust namely water carbon nutrients appropriate temperatures and gradients in redox conditions also occur within mars chemolithoautotrophic microorganisms capable of living below the seafloor on earth would probably survive in some regions of the martian subsurface

the shape propagation and mean flow interaction of large scale weather systems abstract for a zonal average operator the eliassen palm flux provides a diagnostic of both eddy behavior and the feedback of the eddies onto the mean flow this paper addresses the diagnosis problem for other averaging operators and in particular for time averaging which has proved in recent years such a powerful means of viewing the three dimensional tropospheric flow the horizontal velocity correlation tensor gives a measure of the characteristic horizontal eddy shape at a point it also implies the direction of the group velocity relative to the mean flow in cases where such a concept is valid however the major emphasis here is on the mean flow feedback of eddies in this respect the eddy vorticity flux is determined by derivatives of the components of the anisotropic part of the tensor making a reasonable approximation allows the eddy vorticity flux convergence to be written in terms of e v 2 u 2 u v a simple interpretation of the mean flow feedback of eddies is then possible a sligh

a subtropical cyclonic gyre associated with interactions of the mjo and the midlatitude jet abstractthis paper describes a large cyclonic gyre that lasted several days in the northwest pacific during july 1988 cyclonic winds at 850 hpa extended beyond the 2000 km radius with a radius of maximum winds of 700 800 km the gyre exhibited clear skies within and north of its center active convection extended 4000 km in longitude to its south the madden julian oscillation mjo was in its active phase in the indian ocean prior to gyre formation consistent with earlier studies diabatic heating in the mjo was associated with an anomalous upper tropospheric westerly jet over the northeast asian coast and a jet exit region over the northwest pacific repeated equatorward wave breaking events developed downwind of the jet exit region one such event left behind a region of lower tropospheric cyclonic vorticity and convection in the subtropics that played a key role in the gyre formation a second wave breaking event produced strong subsidence north of the mature gyre that contributed to its convective a

evidence for a sill emplacement event on the upper flanks of the ascraeus mons shield volcano mars channels within the ssw rift zone of ascraeus mons a large shield volcano forming part of the tharsis volcanic province on mars have morphological features extremely similar to those of channels identified elsewhere on mars as being due to fluvial action the channel sources are too far from the caldera rim and have the wrong morphology for it to be plausible that the channels were eroded during pyroclastic flow eruptions and the sinuosities are not consistent with scenarios involving lava flows we propose that these channels were formed by meltwater generated and released mainly by relatively slow seepage when a sill was emplaced within or beneath an ice rich permafrost layer smaller fan like channels coalescing into the amphitheater headwall of the wider ones are secondary features produced by further sapping of the undermined flank the minimum dimensions required for the sill 13 by 13 km in lateral extent and 120 m thick are calculated using the thermal exchanges between the sill and the permafrost implied by the volumes of the channel head craters the corresponding minimum sill volume 19 km3 is similar to that df many surface lava flows associated with the tharsis shield volcanoes and is of the order expected for an intrusion resulting from an elastic inflation deflation event in the summit magma reservoir

potential vorticity easterly waves and eastern pacific tropical cyclogenesis abstract a significant sign reversal in the meridional potential vorticity gradient was found during the summer of 1991 on the 310 k isentropic surface near 700 mb over the caribbean sea the charney stern necessary condition for instability of the mean flow is met in this region it is speculated that the sign reversal permits either invigoration of african waves or actual generation of easterly waves in the caribbean during the same season a correlation existed between the strength of the negative potential vorticity gradient in the caribbean and subsequent cyclogenesis in the eastern pacific the meridional pv gradient convective heating measured by outgoing longwave radiation data and eastern pacific cyclogenesis all varied on the timescale of the madden julian oscillation mjo it is hypothesized that upstream wave growth in the dynamically unstable region provides the connection between the mjo or any other convective forcing and the associated enhanced downstream tropical cyclogenesis

development of synoptic scale disturbances over the summertime tropical northwest pacific abstract this study addresses the origin of the synoptic scale disturbances that occur in the tropical western north pacific ocean wp region in northern hemisphere summer these have been called easterly waves and tropical depression type td disturbances this analysis uses the national center for environmental prediction national center for atmospheric research reanalysis dataset by performing a regression analysis on several terms in the vorticity equation at 850 hpa it is shown that the td disturbances propagate approximately as barotropic rossby waves at 850 hpa given this ray tracing calculations and the wave activity diagnostic introduced by plumb are used to show that wave accumulation is a promising candidate for the initial development mechanism of the td disturbances the expected local growth rate from this mechanism is simply the convergence of the group velocity which reaches values corresponding to a growth timescale of 3 days this convergence is dominated by but somewhat lar

chemical components of the martian soil melt degassing hydrothermal alteration and chondritic debris on the basis of measurements by the viking and soviet phobos missions the fine grained surficial drift material on mars is enriched in moderately volatile and mobile elements such as s cl k and br the compounds of these elements may amount to as much as 16 wt of the soil while the bulk of the soil appears to consist primarily of crustal material whose composition is similar to that of the basaltic mars meteorites clark 1993 three possible geochemical sources melt degassing hydrothermal alteration and accretion of chondritic material may have contributed to the enrichments we have evaluated possible chemical signatures for these sources by examining the relative abundances of chemical elements in the different components to the measured k abundance in the mars soil and have identified characteristic elements for each component the relative abundances of mobile elements in the different components are much less variable than their absolute abundances which strongly depend on conditions such as temperature and water composition the volatility controlled elemental signature of the melt degassing process includes enrichments of zn mo cd ba and w relative to the elemental abundances in the other components and martian meteorites hydrothermal alteration of minerals and glass controlled by low temperature solubility makes up a second component with a characteristic lithium enrichment signature a chondritic component is enriched in siderophile and chalcophile elements including ni compared to material derived from the martian mantle which was depleted in siderophile elements due to core formation unfortunately the existing data for the mars soil do not include any of these key signature elements and the uncertainties for the viking analyses could allow large amounts of each of these elements the mars pathfinder inorganic analysis experiment and the 2001 orbital gamma ray experiment have the potential to determine some of these characteristic elements and to reveal the possible contributions to the soil the enriched components of the soil especially cd and pb could also be a potential hazard for future martian explorers who will be exposed to the dust carried into their habitats on their space suits

origin and evolution of the layered deposits in the valles marineris mars abstract thick sequences of layered deposits are found in the martian valles marineris they exhibit fine nearly horizontal layering and are present as isolated plateaus of what may have once been more extensive deposits individual sequences of layered deposits are as thick as 5 km the greatest total thicknesses of deposits are found in candor ophir and melas chasmata individual layer thicknesses range from about 70 to 300 m some tilting of sequences is observed but at the best image resolutions no angular unconformities are detectable in the layers the sequences of events in the canyons as deduced from morphologic and stratigraphic evidence was 1 graben formation in response to the tharsis uplift 2 canyon wall retreat and canyon enlargement roughly contemporaneous with formation of the layered deposits 3 deep erosion of the layered deposits 4 landsliding of the canyon walls and 5 eolian erosion of the layered deposits perhaps continuing up to the present we consider four hypotheses for the origin of the layered deposits they are eolian deposits they are remnants of the material that makes up the canyon walls they are deposits of explosive volcanic eruptions or they were deposited in standing bodies of water the rhythmic nature of the layers and their lateral continuity horizontality great thickness and stratigraphic relationships with other units in the canyons all appear most consistent with deposition in an aqueous environment if standing bodies of water existed in the valles marineris they were almost certainly ice covered there are three ways in which sediment could have entered an ice covered lake down through the ice cover up from the lake bottom or in from the lake margins layers of sediment could have been transported downward through an ice cover by foundering or rayleigh taylor instabilities but it is not clear whether there was a viable mechanism for repeatedly accumulating thick sediment layers on top of the ice cover subaqueous volcanic eruption on the lake bottom does not suffer from many of the morphologic arguments that make origin by subaerial volcanism seem improbable while this mechanism is attractive there are no eruptive centers observed and there is no other direct evidence to support it because canyon enlargement took place at roughly the same time as layer deposition debris from the canyon walls is an obvious and likely source for some of the material in the layered deposits however the volume of material removed from the canyon walls may be insufficient to account for all of the presently observed material we conclude that there are several geologically feasible but as yet unproven mechanisms that could have led to formation of thick deposits in ice covered paleolakes in the valles marineris present data are insufficient to choose conclusively among the various possibilities several types of data from the mars observer mission will be useful in further characterizing the deposits and clarifying the process of their origin the deposits should be considered important targets for a future mars sample return mission

scale interactions during the formation of typhoon irving the development of typhoon irving is investigated using a variety of data including special research aircraft data from the tropical cyclone motion tcm 92 experiment objective analyses satellite data and traditional surface and sounding data the development process is treated as a dry adiabatic vortex dynamics problem and it is found that environmental and mesoscale dynamics mutually enhance each other in a cooperative interaction during cyclone formation synoptic scale interactions result in the evolution of the hostile environment toward more favorable conditions for storm development mesoscale interactions with the low level large scale circulations and with other midlevel mesoscale features result in development of vorticity in the midlevels and enhancement of the low level vorticity associated with the developing surface cyclone multiple developments of mesoscale convective systems after the storm reaches tropical depression strength suggests both an increase in low level confluence and a tendency toward recurrent development of associated mesoscale convective vortices this is observed in both aircraft data and satellite imagery where subsequent interactions including mergers with the low level tropical depression vortex are observed a contour dynamics experiment suggests that the movement of mesoscale convective systems in satellite imagery corresponds well to the movement of their associated midlevel vortices results from a simple baroclinic experiment show that the midlevel vortices affect the large scale low level circulation in two ways 1 initially interactions between midlevel vortices produce a combined vortex of greater depth 2 interaction between midlevel vortices and the low level circulation produces a development downward of the midlevel vorticity this strengthens the surface vortex and develops a more cohesive vortex that extends from the surface through the midtroposphere

abiotic synthesis of polycyclic aromatic hydrocarbons on mars thermochemical calculations of metastable equilibria are used to evaluate the stability of condensed polycyclic aromatic hydrocarbons pahs in cooling thermal gases and hydrothermal fluids on ancient mars which are roughly similar to their terrestrial counterparts the effects of temperature pressure the extent of pah alkylation and the relative stability of pahs and alkanes are considered inhibition of methane and graphite formation favors synthesis of metastable mixtures of hydrocarbons from aqueous or gaseous co co2 and h2 below 200 300 c high temperature quenching of h2 and co in volcanic and impact gases and dynamic hydrothermal fluids also favor the synthesis of hydrocarbons in addition an excess of co in cooling systems relative to equilibrium makes the synthesis from co and h2 more favorable energetically than from co2 and h2 both the co h2 reactions through fischer tropsch ft type processes and the co2 h2 reactions could be catalyzed by magnetite volcanic gases and hydrothermal fluids related to mafic and ultramafic magmas and rocks are more favorable for ft type synthesis than those associated with oxidized fe2o3 bearing rocks and regolith we conclude that pahs and aliphatic hydrocarbons on mars and earth could be formed without the contribution of biogenic carbon some pahs could be formed because of pyrolysis of other hydrocarbons formed earlier by the ft type synthesis or other processes if the pahs found in the alh 84001 martian meteorite formed together with other hydrocarbons through ft type synthesis it may be possible to bracket the temperature of the synthesis the approach presented here can be generalized to study the synthesis of hydrocarbons in terrestrial volcanic and hydrothermal processes

a mossbauer investigation of iron rich terrestrial hydrothermal vent systems lessons for mars exploration hydrothermal spring systems may well have been present on early mars and could have served as a habitat for primitive life the integrated instrument suite of the athena rover has as a component on the robotic arm a mossbauer spectrometer in the context of future mars exploration we present results of mossbauer analysis of a suite of samples from an iron rich thermal spring in the chocolate pots area of yellowstone national park ynp and from obsidian pool ynp and manitou springs colorado we have found that mossbauer spectroscopy can discriminate among the iron bearing minerals in our samples those near the vent and on the surface are identified as ferrihydrite an amorphous ferric mineraloid subsurface samples collected from cores which are likely to have undergone inorganic and or biologically mediated alteration diagenesis exhibit spectral signatures that include nontronite a smectite clay hematite alpha fe2o3 small particle nanophase goethite alpha feooh and siderite feco3 we find for iron minerals that mossbauer spectroscopy is at least as efficient in identification as x ray diffraction this observation is important from an exploration standpoint as a planetary surface instrument mossbauer spectroscopy can yield high quality spectral data without sample preparation backscatter mode we have also used field emission scanning electron microscopy fesem in conjunction with energy dispersive x ray edx fluorescence spectroscopy to characterize the microbiological component of surface sinters and the relation between the microbiological and the mineralogical framework evidence is presented that the minerals found in these deposits can have multi billion year residence times and thus may have survived their possible production in a putative early martian hot spring up to the present day examples include the nanophase property and the mossbauer signature for siderite which has been identified in a 2 09 billion year old hematite rich chert stromatolite our research demonstrates that in situ mossbauer spectroscopy can help determine whether hydrothermal mineral deposits exist on mars which is significant for exobiology because of the issue of whether that world ever had conditions conductive to the origin of life as a useful tool for selection of samples suitable for transport to earth mossbauer spectroscopy will not only serve geological interests but will also have potential for exopaleontology

observation of 3 6 day meridional wind oscillations over the tropical pacific 1973 1992 vertical structure and interannual variability abstract rawinsonde data from tropical pacific stations were examined for westward propagating 3 6 day meridional wind oscillations in the troposphere and lower stratosphere 1973 1992 four types were identified from cross spectrum and principal component analysis 1 the dominant oscillation near 250 mb had a period slightly greater than 5 days zonal wavenumber 4 6 and modified rossby gravity structure near the date line 2 in the western pacific lower troposphere there was broadband activity with short zonal scale coupled to upper tropospheric waves in nh summer 3 in the central pacific during nh autumn there was a well defined 4 day oscillation with maximum amplitude in the lower troposphere and baroclinic phase tilt above the vertical structure suggested coupling to deep tropical convection this interpretation was supported by correlation of meridional wind with antisymmetric outgoing longwave radiation 4 in the stratosphere rossby gravity waves had periods 4 days and zonal wavenu

an air sea interaction theory for tropical cyclones part ii evolutionary study using a nonhydrostatic axisymmetric numerical model abstract in part i of this study an analytical model for a steady state tropical cyclone is constructed on the assumption that boundary layer air parcels are conditionally neutral to displacements along the angular momentum surfaces of the hurricane vortex the reversible thermodynamics implied by this assumption allows the mature storm to be thought of as a simple carnot engine acquiring heat at the high temperature ocean surface and losing heat near the low temperature tropopause although the oceanic heat source is universally recognized as the sine qua non for the mature hurricane there is also wide acceptance of conditional instability of the second kind cisk which makes no specific reference to surface heat fluxes as the formative mechanism this ambivalence is seen in that all numerical simulation studies find it essential to have transfer from the ocean surface yet all start from a conditionally unstable atmosphere the hypothesis put forward in part i based on the steady state theory is t