determination of venus winds by ground based radio tracking of the vega balloons a global array of 20 radio observatories was used to measure the three dimensional position and velocity of the two meteorological balloons that were injected into the equatorial region of the venus atmosphere near venus midnight by the vega spacecraft on 11 and 15 june 1985 initial analysis of only radial velocities indicates that each balloon was blown westward about 11 500 kilometers 8 000 kilometers on the night side by zonal winds with a mean speed of about 70 meters per second excursions of the data from a model of constant zonal velocity were generally less than 3 meters per second however a much larger variation was evident near the end of the flight of the second balloon consistent systematic trends in the residuals for both balloons indicate the possibility of a solar fixed atmospheric feature rapid variations in balloon velocity were often detected within a single transmission 330 seconds however they may represent not only atmospheric motions but also self induced aerodynamic motions of the balloon

extreme alteration by hyperacidic brines at kawah ijen volcano east java indonesia ii metasomatic imprint and element fluxes abstract the hyperacidic brines of the kawah ijen crater lake and banyu pahit river east java indonesia induce an intense alteration on their magmatic host rock this alteration is a proxy for water rock interaction in magmatic hydrothermal systems and associated high sulphidation mineralizing environments as well as for how these systems translate changes in the magmatic system to surface emissions which are used in volcanic hazard monitoring detailed bulk chemical study of altered and unaltered samples shows that alteration is characterised by near complete leaching of all major and trace elements except for pb sn and sb which are progressively enriched pb up to 15 fold absolute enrichment the resulting element release is complementary to the observed changes in composition of the banyu pahit water downstream when corrected for dilution indicating that alteration progressively increases the element load the signature of the change in water chemistry is best explained by complete alteration of fresh rock rather than mature alteration which might be expected given the advanced altered state of the riverbed together with mass balance considerations this indicates that the dominant element source is material falling into the river from the valley flanks the chemical signature of the crater lake is inconsistent with the observed alteration in samples from the hydrothermal system and likewise is best explained by surface input of cations from rocks falling in from the crater walls this indicates that the lake water cation chemistry is not a direct reflection of the underlying magmatic hydrothermal system and that its cation content is therefore not an appropriate monitor of changes in volcanic activity

jarosite occurrence in the deccan volcanic province of kachchh western india spectroscopic studies on a martian analog locality the sulfate mineral jarosite is considered a key indicator of hydrous acidic and oxidizing conditions on the surface of early mars here we report an analog terrestrial locality hosting jarosite from matanumadh kachchh western india using detailed spectroscopic studies on weathered basalts of the deccan volcanic province and overlying tuffaceous shales and sandstones of the matanumadh formation hyperspectral data in the visible near infrared 350 2500 nm to midinfrared 4000 400 cm 1 region of the electromagnetic spectrum and x ray diffraction patterns have been acquired on samples collected from the field to detect and characterize the hydrous sulfate and phyllosilicate phases present at the studied site hydrous sulfates occur in association with al rich phyllosilicates kaolinite that overlie a zone of fe mg smectites in altered basalts jarosite is found within both saprolitic clay horizons altered from the basalt and within variegated sandstone and shale clay units overlying the saprolite it mostly occurs as secondary veins with or without gypsum jarosite is also seen as coatings on kaolinite clasts of varying shapes and sizes within the tuffaceous variegated sandstone unit we argue that the overall geological setting of the matanumadh area with this unusual mineral assemblage developing within altered basalts and in the overlying sedimentary sequence mimics the geological environment of many of the identified jarosite localities on mars and can be considered as a martian analog from this perspective

variable winds on venus mapped in three dimensions 1 we present zonal and meridional wind measurements at three altitude levels within the cloud layers of venus from cloud tracking using images taken with the virtis instrument on board venus express at low latitudes zonal winds in the southern hemisphere are nearly constant with latitude with westward velocities of 105 ms 1 at cloud tops altitude 66 km and 60 70 ms 1 at the cloud base altitude 47 km at high latitudes zonal wind speeds decrease linearly with latitude with no detectable vertical wind shear values lower than 15 ms 1 indicating the possibility of a vertically coherent vortex structure meridional winds at the cloud tops are poleward with peak speed of 10 ms 1 at 55 s but below the cloud tops and averaged over the south hemisphere are found to be smaller than 5 ms 1 we also report the detection at subpolar latitudes of wind variability due to the solar tide

extreme alteration by hyperacidic brines at kawah ijen volcano east java indonesia i textural and mineralogical imprint article kawah ijen volcano located on the eastern tip of java and renowned for its large hyperacidic crater lake poses significant volcanic and environmental hazards to its immediate surroundings crater lake brines seep through the flanks of the volcano to form the banyu pahit river which is used in irrigation downstream resulting in extensive pollution sharply reduced crop yields and health problems the impact on the environment comes mainly from the high element load which is derived from leaching of rocks by the acid fluids and transported downstream our detailed study of water rock interaction in different parts of the kawah ijen system indicates that there are three settings for this alteration the crater lake and banyu pahit riverbed the hydrothermal system below the lake and the solfatara of the active rhyolite dome in all three settings the silicates are leached and altered to amorphous silica in the order olivine glassnan rich plagioclasenortho pyroxenenclino pyroxenenab rich plagioclase in contrast the alteration of titanomag netite is characterised by dissolution in the surficial setting replacement by pyrite and ti oxide in the hydrothermal system and pyritisation ti mobility in the fumarole conduits alteration progresses along crystallographically controlled planes in all phases and shows strong compositional control in plagioclase and titanomagnetite no secondary minerals develop except for minor barite cristobalite pyrite and jarosite this indicates that despite its high element load the waters are undersaturated with respect to most secondary minerals typically produced during alteration of these magmatic rocks by acid chloride sulphate brines and that water rock interaction at kawah ijen is not a sink of elements but rather contributes to the element load transported downstream

south polar features on venus similar to those near the north pole venus has no seasons slow rotation and a very massive atmosphere which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets infrared observations by previous missions to venus revealed a bright dipole feature surrounded by a cold collar at its north pole the polar dipole is a double eye feature at the centre of a vast vortex that rotates around the pole and is possibly associated with rapid downwelling the polar cold collar is a wide shallow river of cold air that circulates around the polar vortex one outstanding question has been whether the global circulation was symmetric such that a dipole feature existed at the south pole here we report observations of venus south polar region where we have seen clouds with morphology much like those around the north pole but rotating somewhat faster than the northern dipole the vortex may extend down to the lower cloud layers that lie at about 50 km height and perhaps deeper the spectroscopic properties of the clouds around the south pole are compatible with a sulphuric acid composition

images from galileo of the venus cloud deck images of venus taken at 418 violet and 986 near infrared nir nanometers show that the morphology and motions of large scale features change with depth in the cloud deck poleward meridional velocities seen in both spectral regions are much reduced in the nir in the south polar region the markings in the two wavelength bands are strongly anticorrelated the images follow the changing state of the upper cloud layer downwind of the subsolar point and the zonal flow field shows a longitudinal periodicity that may be coupled to the formation of large scale planetary waves no optical lightning was detected

mapping zonal winds at venus s cloud tops from ground based doppler velocimetry abstract the most significant aspect of the general circulation of the atmosphere of venus is its retrograde super rotation a complete characterization of this dynamical phenomenon is crucial for understanding its driving mechanisms here we report on ground based doppler velocimetry measurements of the zonal winds based on high resolution spectra from the uv visual echelle spectrograph uves instrument at eso s very large telescope under the assumption of predominantly zonal flow this method allows the simultaneous direct measurement of the zonal velocity across a range of latitudes and local times in the day side the technique based on long slit spectroscopy combined with the high spatial resolution provided by the vlt has provided the first ground based characterization of the latitudinal profile of zonal wind in the atmosphere of venus the first zonal wind field map in the visible as well as new constraints on wind variations with local time we measured mean zonal wind amplitudes between 106 21 and 127 14 m s at latitudes between 18 n and 34 s with the zonal wind being approximately uniform in 2 6 wide latitude bands 0 3 arcsec at disk center the zonal wind profile retrieved is consistent with previous spacecraft measurements based on cloud tracking but with non negligible variability in local time longitude and in latitude near 50 the presence of moderate jets is apparent in both hemispheres with the southern jet being stronger by 10 m s small scale wind variations with local time are also present at low and mid latitudes

high resolution cloud feature tracking on venus by galileo abstract the venus cloud deck was monitored in february 1990 for 16 hours at 400 nanometers wavelength by the galileo imaging system with a spatial resolution of about 15 km and with image time separations as small as 10 minutes velocities are deduced by following the motion of small cloud features in spite of the high temporal frequencies capable of being detected no dynamical phenomena are apparent in the velocity data except the already well known solar tides possibly altered by the slow 4 day wave and the hadley circulation there is no evidence to a level of approximately 4 m s 1 of eddy or wavelike activity the dominant size of sub global scale albedo features is 200 500 km and their contrast is approximately 5 at low latitudes there are patches of blotchy cell like structures but at most locations the markings are streaky the patterns are similar to those discovered by mariner 10 and pioneer venus m j s belton et al 1976 j atmos sci 33 1383 1393 w b rossow et al 1980 j geophys res 85 8107 8128 scaling arguments are presented to argue that the mesoscale blotchy cell like cloud patterns are caused by local dynamics driven in a shallow layer by differential absorption of sunlight it is also argued that mesoscale albedo features are either streaky or cell like simply depending on whether the horizontal shear of the large scale flow exceeds a certain critical value

planetary scale waves and the cyclic nature of cloud top dynamics on venus abstract pioneer venus ocpp ultraviolet images spanning eight years have been analyzed objectively to derive quantitative information on the properties of planetary scale wave modes at the venus cloud tops we infer propagation characteristics for longitudinal wavenumber 1 by fourier analyzing time series of longitudinal mean normalized image brightness the dominant equatorial mode during 1979 80 was the 4 day periodicity associated with zonal motion of the y feature the difference between this and the 4 7 day equatorial rotation period derived from the tracking of small cloud features implies that the y is a propagating wave with a prograde phase speed of about 15 ms 1 relative to the wind simultaneous time series of cloud tracked wind fluctuations also exhibit a 4 day periodicity lending support to the wave interpretation the prograde propagation and equatorial confinement of the wave and the absence of analogous meridional wind fluctuations identify it as a kelvin wave zonal winds peak near the

whangaehu river new zealand geochemistry of a river discharging from an active crater lake abstract during 3 surveys in 1992 water and sediment samples were collected from the length of the whangaehu river and above the confluence points of major tributaries the waters were analysed for major cations ca li mg na anions cl so4 metals al as cd cr cu fe hg mn ni pb and zn sio2 ph conductivity and temperature the sediments were analysed for some metals during 1992 the volcanic crater lake of mt ruapehu intermittently discharged very acid waters into the whangaehu river for example in february during an intense period of snow melt and crater lake overflow the ph of the river water was 2001 sec metal concentrations were similar in the total recoverable and dissolved metal fractions of the water at times of lower overflow

aluminium species distribution during mixing of acid coal and slate mine drainage with neutral stream waters we measured the spatial variation of aluminium concentrations and computed its species distribution before and during mixing of acid mine drainage containing waters with near neutral receiving waters acid mine drainage was collected from the loquitz creek thuringia germany and garvey creek westland new zealand which drain slate mine workings and coal mine workings resp the acidneutralizing capacity anc of the receiving streams and the mixing with waters having low al concentrations cause a decrease of aluminium concentrations below the confluence depending on volumes and ancs involved the content of free al and sulphate bound al decreases after mixing in favour of organic and hydroxide bound al in addition below the junction of the loquitz creek and the aue creek with its high anc we observe the precipitation of aluminium hydroxides and al hydroxysulphates

equilibrium mineral fluid calculations and their application to the solid solution between alunite and natroalunite in the el indio pascua belt of chile and argentina abstract the effects of temperature and bulk fluid k na on the alunite natroalunite solid solution have been determined at 200 bar and 100 300 c these are conditions typical of magmatic hydrothermal alteration and precious metal mineral deposition in high sulfidation environments which are characterized by the presence of alunite bearing alteration zones our model is based on published experimental parameters which indicate that both alunite and natroalunite are stable over this temperature range and that increased na substitution is favored at higher temperature our calculation results predict that at all temperatures fluids in equilibrium with natroalunite are significantly more na rich than those typical of modern volcanic hydrothermal environments the results also indicate that a large variation in fluid k na is required to precipitate both k and na rich alunite at high temperature assuming near equilibrium conditions at lower temperature much less variation in fluid composition can yield compositions near those of the end members controls on alunite natroalunite solid solution in natural systems were evaluated using electron microprobe data from high sulfidation gold deposits of the el indio pascua belt the results indicate that higher temperatures of deposition correlate with a greater range of na substitution in alunite elevated na content in alunite is also locally attributed to higher concentrations of na in the source fluid as a result of the leaching and alteration of andesitic host rocks dacitic to granitic host lithologies in other regions of the belt are correlative with more k rich alunite compositions the results from this study suggest that the use of alunite k na composition as a guide to mineral exploration should be treated with caution

the chemical and hydrologic structure of poa s volcano costa rica comparison of the chemical characteristics of spring and river water draining the flanks of poa s volcano costa rica indicates that acid chloride sulfate springs of the northwestern flank of the volcano are derived by leakage and mixing of acid brines formed in the summit hydrothermal system with dilute flank groundwater acid chloride sulfate waters of the rio agrio drainage basin on the northwestern flank are the only waters on poa s that are affected by leakage of acid brines from the summit hydrothermal system acid sulfate waters found on the northwestern flank are produced by the interaction of surface and shallow groundwater with dry and wet acid deposition of so2 and h2so4 aerosols respectively the acid deposition is caused by a plume of acid gases that is released by a shallow magma body located beneath the active crater of poa s no evidence for a deep reservoir of neutral ph sodium chloride brine is found at poa s the lack of discharge of sodium chloride waters at poa s is attributed to two factors 1 the presence of a relatively volatile rich magma body degassing at shallow depths 1 km into a high level summit groundwater system and 2 the hydrologic structure of the volcano in which high rates of recharge combine with rapid lateral flow of shallow groundwater to prevent deep seated sodium chloride fluids from ascending to the surface the shallow depth of the volatile rich magma results in the degassing of large quantities of so2 and hcl these gases are readily hydrolyzed and quickly mix with meteoric water to form a reservoir of acid chloride sulfate brine in the summit hydrothermal system high recharge rates and steep hydraulic gradients associated with elevated topographic features of the summit region promote lateral flow of acid brines generated in the summit hydrothermal system however the same high recharge rates and steep hydraulic gradients prevent lateral flow of deep seated fluids thereby masking the presence of any sodium chloride brines that may exist in deeper parts of the volcanic edifice structural stratigraphic and topographic features of poa s volcano are critical in restricting flow of acid brines to the northwestern flank of the volcano a permeable lava lahar sequence that outcrops in the rio agrio drainage basin forms a hydraulic conduit between the crater lake and acid chloride sulfate springs spring water residence times are estimated from tritium data and indicate that flow of acid brines from the active crater to the rio agrio source springs is relatively rapid 3 to 17 years hydraulic conductivity values of the lava lahar sequence calculated from residence time estimates range from 10 5 to 10 7 m s these values are consistent with hydraulic conductivity values determined by aquifer tests of fractured and porous lava pyroclastic sequences at the base of the northwestern flank of the volcano fluxes of dissolved rock forming elements in rio agrio indicate that approximately 4300 and 1650 m3 of rock are removed annually from the northwest flank aquifer and the active crater hydrothermal system respectively over the lifetime of the hydrothermal system 100 s to 1000 s of years significant increases in aquifer porosity and permeability should occur in marked contrast to the reduction in permeability that often accompanies hydrothermal alteration in less acidic systems average fluxes of fluoride chloride and sulfur calculated from discharge and compositional data collected in the rio agrio drainage basin over the period 1988 1990 are approximately 2 38 and 30 metric tons day these fluxes should be representative of minimum volatile release rates at poa s in the last 10 to 20 years

the ilopango tierra blanca joven tbj eruption el salvador volcano stratigraphy and physical characterization of the major holocene event of central america abstract the ilopango caldera is the source of the large tierra blanca joven tbj eruption that occurred about 1 5 ka years ago between ca ad270 and ad535 the eruption dispersed volcanic ash over much of the present territory of el salvador and pyroclastic density currents pdcs extended 40 km from the volcano in this study we document the physical characteristics of the deposits from all over el salvador to further constrain the eruption processes and the intensity and magnitude of the different phases of the eruption the succession of deposits generated by the tbj eruption is made of 8 units the eruption started with pdcs of hydromagmatic origin unit a0 followed by fallout deposits units a and b that are

kawah ijen volcanic activity a review kawah ijen is a composite volcano located at the easternmost part of java island in indonesia and hosts the largest natural acidic lake in the world we have gathered all available historical reports on kawah ijen s activity since 1770 with the purpose of reviewing the temporal evolution of its activity most of these observations and studies have been conducted from a geochemical perspective and in punctuated scientific campaigns starting in 1991 the seismic activity and a set of volcanic lake parameters began to be weekly available we present a database of those measurements that combined with historical reports allow us to review each eruption unrest that occurred during the last two centuries as of 2010 the volcanic activity is monitored by a new multi disciplinary network including digital seismic stations and lake level and temperature measurements this detailed monitoring provides an opportunity for better classifying seismic events and forecasting volcanic unrest at kawah ijen but only with the understanding of the characteristics of this volcanic system gained from the historical review presented here

zonal winds in the middle atmosphere of venus from pioneer venus radio occultation data abstract pioneer venus radio occultation data for four seasons between december 1978 and october 1981 are used to construct meridional cross sections of temperature and zonal wind velocity for the middle atmosphere of venus in the altitude range of 40 80 km and in the latitude range of 1 5 85 wind speeds are derived assuming cyclostrophic balance the wind field contains as many as three jets first a prominent one above the clouds situated between 50 and 55 latitude with a maximum speed of 140 m s 1 a second with a speed of 95 m s 1 centered at 70 and at 60 km altitude and a possible third jet at 15 and 65 km altitude with a speed of 100 m s 1 the notable midlatitude jet is associated with the cold polar collar wind speeds above 70 km generally decrease with height because of the warm pole at these levels however within the jet the speed is 100 m s 1 at 83 km the jets may be barotropically unstable and inertial instability may occur above the clouds on the equatorial side of the main

element flux to the environment of the passively degassing crater lake hosting kawah ijen volcano indonesia and implications for estimates of the global volcanic flux volcanoes play an important role in the global cycling of elements by providing a pathway from the deep earth to its surface here we have constrained the flux to the environment for most elements of the periodic table for the passively degassing crater lake hosting kawah ijen volcano in the indonesian arc our results indicate that emissions of kawah ijen are dominated by acid water outflow especially for the ligands cl f br with active fumaroles contributing significant semi metals e g se as sb hg as well as c and s the compositional signature of emissions from kawah ijen is similar to that of major volcanic emitters such as etna but element fluxes are smaller this result provides the prerequisite foundation for extrapolating a small set of measured volcanic gas emissions to a global volcanic flux estimate however the aqueous flux i e seepage of volcanic hydrothermal fluids and volcano influenced groundwater is at least as important in terms of element release and the consideration of the gaseous flux alone thus represents a significant underestimate of the impact of volcanoes on their environment and the contribution of volcanic hydrothermal systems to global element cycling supplementary material the full datasets of water and fumarole gas chemical analyses are available at https doi org 10 6084 m9 figshare c 2134359 to quantify element cycling through the earth and to assess the impact of humanity on these cycles requires precise knowledge of natural fluxes volcanoes represent a direct pathway from the earth s interior to the atmosphere hydrosphere and crust and are an important component of this natural flux they act as point sources with emissions ranging from persistent passive emissions in degassing and outflow of magmatic hydrothermal waters to punctuated release of material during periods of eruption the comprehensive datasets necessary to quantify the output of a volcano are only available for a limited number of terrestrial volcanic centres when estimating global terrestrial volcanic gaseous emissions e g hinkley et al 1999 allard et al 2000 the flux of a single volcano or a small compilation of volcanoes is therefore scaled to a component for which the global volcanic flux is known commonly so2 however this assumes that these emitters are representative of average global volcanism quantification of global volcanic element fluxes has focused on the largest emitters such as etna e g gauthier le cloarec 1998 aiuppa et al 2008 and kilauea hinkley et al 1999 mather et al 2012 with almost no information available for the far more common minor from ohba t capaccioni b caudron c eds geochemistry and geophysics of active volcanic lakes geological society london special publications 437 http doi org 10 1144 sp437 2 2015 the author s published by the geological society of london all rights reserved for permissions http www geolsoc org uk permissions publishing disclaimer www geolsoc org uk pub ethics at simon fraser university on january 18 2016 http sp lyellcollection org downloaded from

the volcanic acidification of glacial lake caviahue province of neuquen argentina abstract lake caviahue northern patagonia argentina is a large glacial lake acidified by volcanic fluids from copahue volcano the lake and the feeding rivers were sampled annually from 1997 till early 2006 including the eruptive period of 2000 lake caviahue waters evolved over time with the most concentrated waters in 2000 during the eruptive period followed by gradual dilution that was interrupted by renewed acidification in 2003 2004 inversion of the lake water data and application of a dynamic non steady state model for the lake provides our best quantitative estimates for the variation in element fluxes over the 9 year period the model flux results agree well with most of the measured fluxes the copahue hydrothermal system had gently declining element fluxes between 1997 and mid 1999 although the lake was still becoming more concentrated about 2 3 months before the 2000 eruption element fluxes increased strongly but the hydrothermal fluxes almost shutoff directly after the main eruptive events the fluxes of several elements recovered post 2001 with an increase in element fluxes in 2003 2004 the lake became more dilute between 2004 and 2006 the intrusion of new magma into the hydrothermal system just prior to the 2000 eruption led to enhanced water rock interaction with higher concentrations of the rock forming elements in the fluids and the hot spring flow rate increased as a result of the higher pressure in the reservoir the fluids became saturated in alunite and jarosite and they were already saturated with anhydrite precipitation of these minerals possibly led to a decreased permeability of the hydrothermal reservoir leading to the strongly reduced element fluxes just after the eruption in addition k al and s were retained in the newly precipitated minerals as well further diminishing their export the acidification in 2003 2004 may have resulted from a new small intrusion of magma or resulted from seismic activity that created new permeability and fresh rock surfaces for water rock interaction the volcano is a significant source of toxic trace elements such as f as b and li as well as a nutrient p for the local watershed monitoring of the hydrothermal fluids in the river that drains copahue especially the s cl mg cl and mg k values as well as the magnitude of the element fluxes would provide the best information for eruption forecasting for this volcano

growth zoned gypsum stalactite from the kawah ijen volcanic lake indonesia records a 40 year record of volcanic activity volcanic crater lakes represent both a significant hazard and an opportunity to monitor the activity of their host volcano unfortunately monitoring efforts especially of lake water composition are commonly limited by the lack of a historical record here we report the results of a study on the kawah ijen crater lake in eastern java indonesia that uses growth zoned gypsum precipitated from lake water seepage as a proxy record of lake water chemistry absolute ages for gypsum growth zones were determined from 210pb radionuclide dating with a newly developed ar kr xe correction for variations in the volcanic flux the resulting 40 year time series of gypsum composition shows that periods of unrest are recorded by large compositional variance whereas quiescence is characterized by low concentrations and low variance gypsum associated with the 1817 phreato magmatic eruption of kawah ijen is similar in most elements but it has markedly higher ratios of cu over sb as and tl which is interpreted to represent a volcanic gas signal these results show that gypsum holds great promise to provide the missing historical record of lake chemistry and unrest at kawah ijen volcano and this approach can be extended to other volcanoes hosting crater lakes where gypsum is present

a reanalysis of venus winds at two cloud levels from galileo ssi images abstract the global circulation of the venus atmosphere is characterized at cloud level by a zonal super rotation studied over the years with data from a battery of spacecrafts orbiters balloons and probes among them the galileo spacecraft monitored the venus atmosphere in a flyby in february 1990 in its route toward jupiter since the flyby was almost equatorial published analysis of zonal winds obtained from displacements of cloud elements on images obtained by the ssi camera belton m j s and 20 colleagues 1991 science 253 1531 1536 stop at latitudes 50 north and south in this paper we present new results on venus winds based on a reanalysis of an extended set of images obtained at two wavelengths 418 nm violet and 986 nm near infrared that sense different altitude levels in the upper cloud our main result is that we have been able to extend the zonal wind profile up to the polar latitudes 70 n and 70 s at 418 nm and 70 n at 986 nm binned and smoothed profiles are given in tabular form we show that the zonal winds drop in their velocity poleward of latitudes 45 n and 50 s where an intense meridional wind shear develops at the two cloud levels our data confirm the magnitude of this shear retrieved previously from radio occultation data but disagrees with it in the latitudinal location of the sheared region the new wind data can be used to recalibrate the zonal winds retrieved from the previous measurements of the temperature field and the cyclostrophic balance assumption the meridional profiles of the zonal winds at the two cloud levels are used to assess the vertical wind shear in the upper cloud layer as a function of latitude and locate the most unstable region

using the composition of fluid seepage from the magmatic hydrothermal system of kawah ijen volcano indonesia as a monitoring tool abstract the lake waters of kawah ijen volcano are concentrated hyperacidic brines that obtain their composition from volcanic gases and water rock interaction lake water and hydrothermal fluids seep through the western flank of the volcano where they precipitate gypsum and form the hyperacid banyu pahit river in this contribution we present compositional data from bi weekly samples taken from the banyu pahit between 2015 and 2018 to evaluate whether these fluids can be used to monitor the hydrothermal system and compare the fluids to the record of variability documented by the precipitated gypsum understanding the causal links between variability of the banyu pahit and the magmatic hydrothermal processes operating in the kawah ijen system and establishing a baseline for quiescence are pre requisites to using the river for monitoring fluid samples were analysed at the ijen observatory for so4 cl ratio using baso4 turbidity and agcl gravimetry and subsequently sent for icp ms and icp oes analyses the data shows a first order seasonal variation that can be explained by variable input of neutral groundwater but is underlain by more subtle trends temporally there is a shift in the system from 2015 to 2016 to 2017 when the fluid contains a higher proportion of elements derived from rock alteration the shift occurs at the peak of the rainy season and coincides with a substantial rainfall increase in 2017 compared to 2015 2016 at the start of 2018 there is a marked increase in cu coinciding with a gas burst in march 2018 we suggest that an increased meteoric water input led to an increase in water rock interaction and dissolution of a cu sulphide phase in the hydrothermal system the variability of the fluids over the 3 year sampling period does not exceed that of the longer record preserved by the gypsum precipitates indicating that it is typical for the current style of activity

sulfide breakdown controls metal signature in volcanic gas at kawah ijen volcano indonesia abstract immiscible sulfide liquid is thought to be an important intermediary in volcanic degassing of sulfur and chalcophile elements by concentrating and transferring metals from magma to hydrous fluid here we track the interaction of sulfide liquid with a fluid exsolving from basalt at kawah ijen volcano in indonesia as in many other volcanic systems neither sulfide nor fluid is preserved instead the reaction is recorded in changes in metal and sulfur concentrations in the melt during magma ascent and shows a two stage evolution deep seated progressive breakdown of sulfide during which metal concentrations in the melt are largely controlled by the sulfide followed by fluid melt partitioning controlling metal concentrations at shallow depth once this sulfide has been exhausted present day fumarole gases have similar zn cu pb cu and mo cu ratios to the reconstructed sulfide but are enriched in tl as and sb these enrichments are also observed in melt inclusions in the most recent dacitic deposits at kawah ijen this suggests that the fumarole gases are sourced from a deep degassing sulfide saturated basalt preserved in zn cu pb cu and mo cu ratios which subsequently interact with a shallow dacitic melt that enhances tl as and sb emissions

geochemistry of the magmatic hydrothermal system of kawah ijen volcano east java indonesia samples from kawah ijen crater lake spring and fumarole discharges were collected between 1990 and 1996 for chemical and isotopic analysis an extremely low ph 0 3 lake contains so 4 cl waters produced during absorption of magmatic volatiles into shallow ground water the acidic waters dissolve the rock isochemically to produce immature solutions the strong d and 18 o enrichment of the lake is mainly due to enhanced evaporation at elevated temperature but involvement of a magmatic component with heavy isotopic ratios also modifies the lake d and 18 o content the large so4 s d 23 8 26 4 measured in the lake suggest that dissolved so 4 forms during disproportionation of magmatic so 2 in the hydrothermal conduit at temperatures of 250 280 c the lake 18 o so4 and 18 o h2o values may reflect equilibration during subsurface circulation of the water at temperatures near 150 c significant variations in the lake s bulk composition from 1990 to 1996 were not detected however we interpret a change in the distribution and concentration of polythionate species in 1996 as a result of increased so 2 rich gas input to the lake system thermal springs at kawah ijen consist of acidic so 4 cl waters on the lakeshore and neutral ph hco 3 so 4 cl na waters in blawan village 17 km from the crater the cation contents of these discharges are diluted compared to the crater lake but still do not represent equilibrium with the rock the so 4 cl ratios and water and sulfur isotopic compositions support the idea that these springs are mixtures of summit acidic so 4 cl water and ground water the lakeshore fumarole discharges t 170 245 c have both a magmatic and a hydrothermal component and are supersaturated with respect to elemental sulfur the apparent equilibrium temperature of the gas is 260 c the proportions of the oxidized so 2 dominated magmatic vapor anti of the reduced h 2 s dominated hydrothermal vapor in the fumaroles varied between 1979 and 1996 this may be the result of interaction of so 2 bearing magmatic vapors with the summit acidic hydrothermal reservoir this idea is supported by the lower h 2 s so 2 ratio deduced for the gas producing the so 4 cl reservoir feeding the lake compared with that observed in the subaerial gas discharges the condensing gas may have equilibrated in a liquid vapor zone at about 350 c elemental sulfur occurs in the crater lake environment as banded sediments exposed on the lakeshore and as a subaqueous molten body on the crater floor the sediments were precipitated in the past during inorganic oxidation of h 2 s in the lake water this process was not continuous but was interrupted by periods of massive silica poorly crystallized precipitation similar to the present day lake conditions we suggest that the factor controlling the type of deposition is related to whether h 2 s or silica rich volcanic discharges enter the lake this could depend on the efficiency with which the lake water circulates in the hydrothermal cell beneath the crater quenched liquid sulfur products show 34 s values similar to those found in the banded deposits suggesting that the subaqueous molten body simply consists of melted sediments previously accumulated at the lake bottom

bathymetric and geochemical investigation of kawah ijen crater lake east java indonesia abstract a bathymetric survey of kawah ijen crater lake was conducted by acoustic sounding in 1996 to compare the lake morphology with those measured in 1922 1925 and 1938 and to calculate the present lake volume even though the lake experienced several hydrothermal eruptions the maximum depth became shallower 182 m than before 200 m resulting in a reduced lake volume 3 0 10 7 m 3 fifty two major and minor constituents including rare earth elements and polythionates pt of the lake waters at various depths were determined by icp aes icp ms and hplc respectively these ions except for several volatile elements are taken up by lake fringe through congruent dissolution of pyroclastics of kawah ijen volcano most ions are homogeneously distributed throughout the lake although pt showed a considerable vertical variation rare earth elements ree in the kawah ijen water as well as those from other hyper acidic crater lakes show distribution patterns likely due to the three rock dissolution preferential congruent and residual types and their logarithmic concentrations linearly depend upon the ph values of the lake waters using the pt degradation kinetics data production rates of pt injection rates of so 2 and h 2 s into the lake were estimated to be 114 86 and 30 tons day respectively also travel time of the spring water at the banyupahit riverhead from kawah ijen was estimated to be 600 1000 days through the consideration of decreasing rates of pt molten sulfur stocks containing sn cu bi sulfides and pb barite exposed on the inner crater slope were presumed to be extinct molten sulfur pools at the former lake bottom this was strongly supported by the barite precipitation temperature estimated through the consideration of the temperature dependence of pb chlorocomplex formation

geochemistry of the acid kawah putih lake patuha volcano west java indonesia abstract kawah putih is a summit crater of patuha volcano west java indonesia which contains a shallow 300 m wide lake with strongly mineralized acid sulfate chloride water the lake water has a temperature of 26 34 c ph s tot 2500 4600 ppm and cl 5300 12 600 ppm and floating sulfur globules with sulfide inclusions are common sulfur oxyanion concentrations are unusually high with s 4 o 6 2 s 5 o 6 2 s 6 o 6 2 2400 4200 ppm subaerial fumaroles thermodynamic modeling of the lake fluids indicates that the lake water is saturated with silica phases barite pyrite and various pb sb cu as bi bearing sulfides when sulfur saturation is assumed precipitating phases predicted by the model calculations are consistent with the bulk chemistry of the sulfur rich bottom sediments and their identified mineral phases much of the lake water chemistry can be explained by congruent rock dissolution in combination with preferential enrichments from entering fumarolic gases or brines and element removal by precipitating mineral phases as indicated by a comparison of the fluids volcanic rocks and lake bed sediment flank springs on the mountain at different elevations vary in composition and are consistent with local rock dissolution as a dominant factor and ph dependent element mobility discharges of warm sulfate and chloride rich water at the highest elevation and a near neutral spring at lower level may contain a small contribution of crater lake water the acid fluid induced processes at patuha have led to the accumulation of elements that are commonly associated with volcano hosted epithermal ore deposits the dispersal of heavy metals and other potentially toxic elements from the volcano via the local drainage system is a matter of serious environmental concern

ground based near infrared imaging observations of venus during the galileo encounter near infrared images of venus obtained from a global network of ground based observatories during january and february 1990 document the morphology and motions of the night side near infrared markings before during and after the galileo venus encounter a dark cloud extended halfway around the planet at low latitudes 40 and persisted throughout the observing program it had a rotation period of 5 5 0 15 days the remainder of this latitude band was characterized by small scale 400 to 1000 kilometers dark and bright markings with rotation periods of 7 4 1 days the different rotation periods for the large dark cloud and the smaller markings suggests that they are produced at different altitudes mid latitudes 40 to 60 were usually occupied by bright east west bands the highest observable latitudes 60 to 70 were always dark and featureless indicating greater cloud opacity maps of the water vapor distribution show no evidence for large horizontal gradients in the lower atmosphere of venus

impact of hydrothermal alteration processes on element mobility and potential environmental implications at the sousaki solfataric field corinthia greece abstract samples of efflorescences and encrustations of hydrothermal origin were collected at sousaki greece and analysed for their mineralogical xrd and chemical composition solutions obtained both from mineralization with hno3 and from leaching with deionised water were analysed for major icp oes minor and trace metals icp ms and sulfate contents ic results evidence the dependence of the chemical and mineralogical composition on micro environmental conditions i e humidity oxygen rich or poor environment exposed or sheltered from meteoric agents in fact the presence of highly soluble sulfate minerals with elevated contents of many metals e g mg al fe mn cr ni etc further underscores the important influence of hydrothermal activity on elements mobility whilst the sometimes very high concentrations in toxic elements like al cr ni suggest also possible environmental impacts

co2 emissions from fogo intracaldera volcanic lakes sao miguel island acores a tool for volcanic monitoring abstract a geochemical study was carried out at fogo lake during june 2016 in one of the deepest lakes on sao miguel island as well as on small associated pond in order to identify possible anomalous degassing areas fogo lake is located inside the summit caldera of fogo volcano one of the three active central volcanoes that dominate sao miguel geology the hydrogeochemical profile carried out along the water column of the fogo lake suggests that the lake was thermally stratified corresponding to poorly mineralized and cold na cl type waters the same composition is found in the small pond but with a slight ca enrichment to measure the co2 flux at the lake surface the modified accumulation chamber method was used and a total of 1696 measurements were accomplished covering an area of approximately 1 56 km2 measured co2 flux values are relatively low ranging from 0 to 28 4 g m 2 d 1 mean 2 6 g m 2 d 1 and from 2 1 to 15 0 g m 2 d 1 mean 6 3 g m 2 d 1 respectively at fogo lake and at the small pond the very low values measured in the central area of fogo lake are associated with the monomictic character of the lake as the co2 is not able to ascend into the surface when the water column is stratified during the warmer period statistical analyses suggest that the co2 emission is associated with a single source of co2 probably biogenic a similar signature is pointed by the water 13c isotopic content the estimated total co2 emissions from the fogo lake was approximately 4 04 t d 1 much higher than the value observed at the small pond 0 19 t d 1

acid sulfate chloride volcanic waters formation and potential for monitoring of volcanic activity abstract this paper deals mainly with acidic sulphate chloride asc waters that are discharged at volcanic edifices generally not associated with crater lakes geographically the largest number of such manifestations were found on japanese and kuril islands these waters are formed by 1 condensation of magmatic vapor under shallow conditions and or 2 dissolution of magmatic gases in underground waters 3 near surface mixing of steam heated sulphate waters with sodium chloride waters of deeper formation 4 interaction of sodium chloride waters with the rocks undergone by argillic and advanced argillic alteration including hydrolysis of elemental sulfur 5 a combination of several of the listed processes criteria to assess the nature of such waters using their chemical and isotopic composition are based on the relative abundances of major species and trends in isotopic compositions generally controlling by mixing of magmatic host rock meteoric endmembers an overview of available data on temporal chemical variations of such waters shows that usually volcanic activity is marked by an increase in the so4 cl ratio during or after the eruptive event the response on the volcanic activity depends on hydrogeological conditions that control the appearance of the asc springs

venus atmospheric circulation known and unknown 1 after a pause of more than two decades venus atmosphere is being explored again since april 2006 european space agency s venus express has been acquiring data exploiting the near infrared windows that allow us to peer into the deep night side atmosphere in june 2007 nasa s messenger mission will fly past venus on its way to mercury collecting useful data for a few weeks instruments and experiments on venus express are expected to provide a more comprehensive set of atmospheric observations over three and perhaps more venus days venus express observations are already providing clues about the processes that maintain the rapid circulation of venus atmosphere the early observations show not only that the global circulation is organized into two hemispheric vortices centered over respective poles but also that the vortex organization extends deep into the atmosphere the limited galileo nims near infrared observations in 1989 had revealed the deep circulation in the equatorial regions but because of the spacecraft flyby trajectory could not observe the high latitudes to elucidate the polar circulation and its organization the long hiatus in systematic venus observations has provided an opportunity to perform some new analysis of the previous pioneer venus observations this paper presents a synopsis of the circulation measurements at high latitudes and an analysis of the solar thermal tides seen in the cloud motions and suggests some limitations of previous estimates of transport of angular momentum by eddies

geochemistry mineralogy and chemical modeling of the acid crater lake of kawah ijen volcano indonesia the kawah ijen volcano with a record of phreatic eruptions has its 1000 m wide crater filled with a lake that has existed for at least one century at present the lake waters are hot t 37 c strongly mineralized tds 105 g l and extremely acidic ph 0 4 by its volume the javanese lake is probably the largest accumulation in the world of such acidic waters mineralogy of the suspended solids within the lake waters suggests that concentrations of si ca ti and ba are controlled by precipitation of silica gypsum anatase and barite lake sediment is composed of chemical precipitates with composition similar to the suspended solids thermodynamic calculations predict that the lake waters have reached equilibrium with respect to cristobalite barite gypsum anglesite celestite and amorphous silica in agreement with the analytical observations significant concentrations of ferric iron suggest that the current lake waters are fairly oxidized sulfides are absent in the water column but are always present in the native s spherules that form porous aggregates which float on the lake the presence of native s provides direct evidence of more reduced conditions at the lake floor where h 2 s is probably being injected into the lake with progressive addition of h 2 s to the acid waters native s pyrite and enargite are theoretically predicted to be saturated reactions between upward streaming h 2 s bearing gases discharged by subaqueous fumaroles and metals dissolved in the acidic waters could initiate precipitation of these sulfides a model of direct absorption of hot magmatic gases into cool water accounts for the extreme acidity of the crater lake results show that strongly acidic sulfate rich solutions are formed under oxidizing conditions at high gas water ratios reactions between the acidic fluids and the ijen andesite were modeled to account for elevated cation concentrations in lake water current concentrations of conservative rockforming elements are produced by dissolution of approximately 60 g of andesite per kg of acid solution complete neutralization of the acid lake waters by reaction with the wallrock produces a theoretical alteration assemblage equivalent to that observed in volcano hosted acid sulfate epithermal ore deposits

impact of acid effluent from kawah ijen crater lake on irrigated agricultural soils soil chemical processes and plant uptake abstract volcanogenic contamination of irrigation water caused by effluent from the hyperacid ijen crater lake has severely affected the properties of agricultural soils in east java indonesia from a comparison of acidified topsoil with subsoil and with top and subsoil in a reference area we identified processes responsible for changes in soil and soil solution chemistry induced by acid irrigation water with emphasis on the nutrients ca mg fe and mn and on al which may become phytotoxic under acid conditions in soils compositional data for bulk soil composition and selective extractions with 1 m kcl and 0 2 m acid ammonium oxalate are used in a mass balance approach to specify element fluxes including uptake by rice plants the results show that input via irrigation water has produced an increase in the total aluminum content in the affected topsoil which is of the same order of magnitude as the increase in labile al high bioavailability of al as reflected by concentrations in kcl extracts is consistent with elevated concentrations observed in rice plants in contrast and despite the high input via irrigation water ca and mg concentrations have decreased in all measured soil fractions through dissolution of amorphous phases and minerals and through competition of al for adsorption sites on the exchange complex and plant roots strong leaching is also evident for fe and especially mn in terms of the overall mass balance of the topsoil plant uptake of al ca fe mg and mn is negligible if the use of acid irrigation would be stopped and the soil ph were to increase to values above 4 5 the observed phytotoxicity of al will be halted however crops may then become fully dependent on the input from irrigation water or fertilizer for essential elements due to the previous removal from the topsoil through leaching

downstream composition changes of acidic volcanic waters discharged into the banyupahit stream ijen caldera indonesia abstract the crater lake of kawah ijen volcano contains extremely low ph we discuss the downstream composition changes affecting the banyupahit waters by using stable isotope chemical and mineralogical data collected from sites along the stream length the saturation of the stream waters with respect to minerals was evaluated with solveq and wateq4f and compared with the geochemical observations an aluminous mineralogy alunogen pickeringite tamarugite and kalinite develops in the upper part of the banyupahit due to concentration of the headwaters by evaporation downstream attenuation of dissolved element concentrations results principally from dilution and from mineral precipitation the stream ph changes from 0 at the source to 4 close to the mouth the d and 18o values and the relative so4 cl f contents of the banyupahit waters indicate that the tributaries are mostly meteoric dissolved so4 in the acidic stream come only from the crater lake seepages and are not involved later in microbially mediated reactions as shown by their 34s and 18o values re equilibration of the stream so4 oxygen isotope composition with h2o from tributaries does not occur calcium sio2 al fe k and so4 behave non conservatively in the stream waters gypsum silica amorphous or poorly ordered a basic aluminum hydroxysulfate basaluminite k jarosite and amorphous ferric hydroxide may exert a solubility control on these elements along the entire stream length or in certain stream sections consistent with the thermochemical model results downstream concentration trends and mineral saturation levels suggest that precipitation of sr pb rich barite and celestite consume ba sr and pb whereas dissolved cu pb and zn may adsorb onto solid particles especially after the junctions of the acidic stream with non acidic rivers we calculated that significant fluxes of so4 f cl al sio2 ti mn and cu may reach the irrigation system possibly causing serious environmental impacts such as soil acidification and induration

new insights into the kawah ijen hydrothermal system from geophysical data corentin caudron 1 2 3 guillaume mauri 4 glyn williams jones 5 thomas lecocq2 devy kamil syahbana 6 raphael de plaen 7 loic peiffer 8 alain bernard 3 ginette saracco 9 1 earth observatory of singapore nanyang technological university 50 nanyang av block n2 01a 15 singapore 639798 2 royal observatory of belgium seismology section 3 avenue circulaire 1180 uccle belgium 3 department of earth environmental sciences universite libre de bruxelles 50 ave roosevelt 1050 brussels belgium 4 center for hydrogeology and geothermics university of neuchtel neuchtel switzerland 5 department of earth sciences simon fraser university 8888 university drive burnaby british columbia v5a 1s6 canada 6 centre for volcanology and geological hazard mitigation geological agency ministry of energy and mineral resources jalan diponegoro 57 bandung 40122 indonesia 7 university of luxembourg faculte des sciences de la technologie et de la communication 6 rue richard coudenhove kalergi l 1359 luxembourg 8 instituto de energi as renovables universidad nacional auto noma de me xico privadaxochicalco s n centro 62580 temixco morelos mexico 9 cnrs umr7330 centre europeen de recherche et d enseignement en geosciences de l environnement cerege equipe modelisation aix marseille universite amu europole de l arbois bp 80 13545 aix en provence cedex 4 france ginet cerege fr corresponding author e mail corentin caudron gmail com abstract the magmatic hydrothermal system of kawah ijen volcano is one of the most exotic on earth featuring the largest acidic lake on the planet a hyper acidic river and a passively degassing silicic dome while previous studies have mostly described this unique system from a geochemical perspective to date there has been no comprehensive geophysical investigation of the system in our study we surveyed the lake using a thermocouple a thermal camera an echo sounderand co2 sensors furthermore we gained insights into the hydrogeological structures by combining self potential surveys with ground and water temperatures our results show that the hydrothermal system is self sealed within the upper edifice and releases pressurized gas only through the active crater we also show that the extensive hydrological system is formed by not one but three aquifers a south aquifer that seems to be completely isolated a west aquifer that sustains the acidic upper springs and an east aquifer that is the main source of fresh water for the lake in contrast with previous research we emphasize the heterogeneity of the acidic lake illustrated by intense subaqueous degassing these findings provide new insights into this unique hazardous hydrothermal system which may eventually improve the existing monitoring system

recycling of pleistocene valley fills dominates 135 ka of sediment flux upper indus river abstract rivers draining the semiarid transhimalayan ranges at the western tibetan plateau margin underwent alternating phases of massive valley infill and incision in pleistocene times the effects of these cut and fill cycles on millennial sediment fluxes have remained largely elusive we investigate the timing and geomorphic consequences of headward incision of the zanskar river a tributary to the indus which taps the 250 m thick more plains valley fill that currently plugs the endorheic high altitude basins of tso kar and tso moriri in situ 10be exposure dating and topographic analyses show that a phase of valley infill gave way to net dissection and the nw himalaya s first directly dated stream capture in late marine isotope stage mis 6 135 ka ago headwaters of the indus are currently capturing headwaters of the sutlej and rivers have eroded 14 7 km3 of sediment from the zanskar headwaters since mobilising an equivalent of 8 of the indus contemporary sediment storage volume from only 0 3 of its catchment area the resulting specific sediment yields are among the rarely available rates averaged over the 105 yr timescale and surpass 10be derived denudation rates from neighbouring catchments three to tenfold we conclude that recycling of pleistocene valley fills has fed transhimalayan headwaters with more sediment than liberated by catchment denudation at least since the last glacial cycle began this protracted release of sediment from thick pleistocene valley fills might bias estimates of current sediment loads and long term catchment denudation

morphology and dynamics of the upper cloud layer of venus esa s venus express probe has been in orbit since april 2006 eight research papers in this issue present new results from the mission covering the atmosphere polar features interactions with the solar wind and the controversial matter of venusian lightning hakan svedham et al open the section with a review of the similarities and mostly differences between venus and its twin the earth andrew ingersoll considers the latest results and also how the project teams plan to make the most of the probe s remaining six years of life venus is completely covered by a thick cloud layer with the cloud tops in fast retrograde rotation global and small scale properties of these clouds and their temporal and latitudinal variations are investigated and the wind velocities are derived the southern polar region is highly variable and can change dramatically on time scales as short as one day perhaps arising from the injection of so2 into the mesosphere venus is completely covered by a thick cloud layer of which the upper part is composed of sulphuric acid and some unknown aerosols1 the cloud tops are in fast retrograde rotation super rotation but the factors responsible for this super rotation are unknown2 here we report observations of venus with the venus monitoring camera3 on board the venus express spacecraft we investigate both global and small scale properties of the clouds their temporal and latitudinal variations and derive wind velocities the southern polar region is highly variable and can change dramatically on timescales as short as one day perhaps arising from the injection of so2 into the mesosphere the convective cells in the vicinity of the subsolar point are much smaller than previously inferred4 5 6 which we interpret as indicating that they are confined to the upper cloud layer contrary to previous conclusions7 8 but consistent with more recent study9

galileo infrared imaging spectroscopy measurements at venus during the 1990 galileo venus flyby the near infaied mapping spectrometer investigated the night side atmosphere of venus in the spectral range 0 7 to 5 2 micrometers multispectral images at high spatial resolution indicate substanmial cloud opacity variations in the lower cloud levels centered at 50 kilometers altitude zonal and meridional winds were derived for this level and are consistent with motion of the upper branch of a hadley cell northern and southern hemisphere clouds appear to be markedly different spectral profiles were used to derive lower atmosphere abundances of water vapor and other species

cloud tracked winds from pioneer venus ocpp images abstract analysis of ultraviolet image sequences obtained from the pioneer venus orbiter cloud photopolarimeter and covering five 80 day periods from 1979 1985 provides the first climatological description of the cloud top circulation on venus the average zonal winds can be characterized as a 5 day retrograde rotation of the whole cloud level atmosphere with weak jets at middle to high latitudes both the midlatitude and equatorial zonal winds vary by about 5 8 m s 1 over time spans of 1 6 years the average meridional circulation is poleward in both hemispheres up to at least 60 latitude consistent with the presence of a thermally direct hadley circulation associated with the clouds the strength of the hadley circulation also varies with time four wave modes are clearly identified a diurnal solar tide a semi diurnal solar tide a 4 day equatorial wave and a 5 day midlatitude wave the semidiurnal tide appears to have an amplitude of about 5 m s 1 and to be approximately constant with time

naturally acid waters from copahue volcano argentina volcanic acid sulfate chloride brines form through absorption of volcanic vapors in shallow reservoirs of meteoric water reaction with surrounding volcanic rocks leads to partial neutralization of the fluids and precipitation of secondary minerals chemical data of such acid waters from copahue volcano argentina covering 8 years of observations show evidence for changes in composition related to water rock interaction at depth prior to emergence of the fluids at the surface the chemical composition changed dramatically during the 2000 eruption of copahue with enhanced concentrations and fluxes of mg na fe and al followed in 2001 by rapidly declining concentrations and element fluxes the subsequent 5 years saw more variable element ratios and strong depletions in k and al most incompatible elements are released from the rock matrix stochiometrically whereas some elements are enriched through vapor input from the magma as pb zn most fluids have lree enrichments relative to the rock matrix but during periods of new magma intrusion the lree enrichment decreases as does the magnitude of the negative eu anomaly in the fluids these observations are interpreted assuming early dissolution of plagioclase olivine and volcanic glass that occurs during intrusion of new magma into the hydrothermal system the high field strength elements are virtually immobile even in these hot acid fluids with nb and ta more so than hf and zr the mobility of u and th in these fluids is comparable at variance with th behavior in neutral fluids the local rivers and lakes of copahue are fertilized by volcanic dissolved p and most surface waters with ph 3 have high levels of as the acid fluids from copahue may be surficial analogs for deep subduction fluids that evolve below zones of arc magma generation as well as for early mars environments that are thought to have had large acid lakes