waves advection and cloud patterns on venus abstract the stable layers adjacent to the nearly neutral layer within the venus clouds are found to be capable of supporting vertically trapped horizontally propagating waves with horizontal wavelengths of about 10 km and speeds of a few meters per second relative to the mean wind in the neutral layer these waves may possibly be excited by turbulence within the neutral layer we examine the properties of the waves and the patterns which they might produce within the visible clouds if excited near the subsolar point the patterns can be in agreement with many features in images the waves are capable of transferring momentum latitudinally to help maintain the general atmospheric spin but at present we are not able to evaluate wave amplitudes we also examine an alternative possibility that the cloud patterns are produced by advection and shearing by the mean zonal and meridional flow of blobs formed near the equator we conclude that advection and shearing by the mean flow is the most likely explanati

probing venus surface iron contents with six band visible near infrared spectroscopy from orbit machine learning models enable interpretation of orbital spectral measurements of venus using laboratory calibration data collected at venus surface temperatures partial least squares models show that total iron content can be accurately predicted using data from the six bands two in the 1 02 m window prediction errors on total wt feo are 0 50 for common subalkaline volcanic rocks accuracy is 0 42 for wt feo in alkaline rocks and 2 47 for all 18 igneous samples studied to date these robust capabilities will allow discrimination of basalt versus rhyolite granite and elucidate the rock type of the enigmatic tessera terrain on venus

venus express virtis observations of middle and lower cloud variability and implications for dynamics 1 we present an analysis of venus express visible and infrared thermal imaging spectrometer virtis data carried out to characterize the morphological geographical and evolutionary trends of the middle and lower cloud features that are observed in the atmosphere of venus as variations in brightness temperatures in specific near infrared wavelengths in this preliminary study we analyze only data collected over the span of 11 orbits the mean radiance as a function of latitude is consistent with previous ground based observations indicating that the overall global distribution of mean cloud cover is stable at least on a 10 to 20 year time scale in contrast with the consistent level of radiance at high latitudes a significant amount of variability to the radiance exists at lower latitudes consistent with significant convective activity in the lower and middle cloud decks the morphology of the holes tends from highly variable orientations of features with aspect ratios of nearly one at low latitudes to very large aspect ratios and zonally oriented features at higher latitudes the peak radiance of the holes appears not to demonstrate a latitudinal tendency there is evidence of more variability to the morphology and radiance of features at lower latitudes to investigate the evolution of the holes we examine a sequence of images taken over a 5 h span of a single orbit if this limited amount of data is representative then the typical e folding time scale for the evolution of a hole is about 1 day

on observing the compositional variability of the surface of venus using nightside near infrared thermal radiation 1 there are several windows in the near infrared wavelength range 1 m in which thermal radiation emitted from the planetary surface penetrates through the thick venus atmosphere and clouds in this study we develop an improved method to estimate the surface emissivity on the basis of near infrared thermal emission from the nightside venus which is observed through these windows a simple radiative transfer model demonstrates that multiple reflection of thermal radiation between the atmosphere including clouds and the solid surface has a significant influence on the observed radiance under the condition of venus where reflectivity of overlying atmosphere and clouds is high thus it is necessary to take the effect of the reflection by the planetary surface into account in order to estimate accurately the variation in the surface emissivity on the basis of near infrared observation of venus the net effect of multiple reflection of surface thermal radiation between the atmosphere and the surface is to significantly reduce the spatial contrast in thermal radiation due to surface compositional variation the model calculation demonstrates that despite this effect detection of granitic rocks on the venus surface using near infrared windows is feasible since granitic and basaltic rocks have dramatically different 1 m emissivities granitic rocks are distinguishable from basaltic rocks by ground based telescopic observation a venus orbiter that measures both the near infrared thermal radiation and the surface altitude with great accuracy will provide us with a reliable surface emissivity map of venus which is a very valuable tool to detect granitic i e earth like continental rocks on venus

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

characterization of mesoscale gravity waves in the upper and lower clouds of venus from vex virtis images 1 images obtained from the visible and infrared thermal imaging spectrometer virtis m instrument onboard venus express present visible trains of alternating bands of cloud brightness in two different layers at the upper cloud tops 66 km altitude observed in the dayside hemisphere using reflected ultraviolet light 380 nm and in the lower cloud 47 km altitude observed in the nightside hemisphere using thermal radiation 1 74 m the waves are nearly zonal with the bands perpendicular to latitude circles have wavelengths of 60 150 km propagate westward with low phase velocities relative to the zonal flow and are confined in wave packets of 400 to 1800 km in length the waves in the lower cloud observed in the infrared are widely distributed around the planet and their appearance varies widely throughout the virtis data set the locations of both types of waves seem not correlated with latitude local times surface topography or the structure of the wind in both cases the characteristics of the waves correspond to gravity waves propagating in confined stable layers of the atmosphere we examine the properties of these waves in terms of a linear model and perform a simple analysis to discuss the vertical stability of the atmosphere within venus clouds

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

winds in the middle cloud deck from the near ir imaging by the venus monitoring camera onboard venus express for more than 8 years the venus monitoring camera vmc onboard the venus express orbiter performed continuous imaging of the venus cloud layer in uv visible and near ir filters we applied the correlation approach to sequences of the near ir images at 965 nm to track cloud features and determine the wind field in the middle and lower cloud 49 57 km from the vmc images that spanned from december of 2006 through august of 2013 we derived zonal and meridional components of the wind field in low to middle latitudes 5 65 s the velocity of the retrograde zonal wind was found to be 68 70 m s the meridional wind velocity slowly decreases from peak value of 5 8 1 2 m s at 15 s to 0 at 65 70 s the mean meridional speed has a positive sign at 5 65 s suggesting equatorward flow this result together with the earlier measurements of the poleward flow at the cloud tops indicates the presence of a closed hadley cell in the altitude range 55 65 km long term variations of zonal and meridional velocity components were found during 1 200 earth days of observation at 20 5 s the zonal wind speed increases from 67 18 1 81 m s to 77 30 2 49 m s the meridional wind gradually increases from 1 30 1 82 m s to 8 53 2 14 m s following bertaux et al 2016 we attribute this long term trend to the influence from the surface topography on the dynamical process in the atmosphere via the upward propagation of gravity waves that became apparent in the vmc observations due to slow drift of the venus express orbit over aphrodite terra

galileo infrared imaging spectrometry measurements at the moon imaging spectrometer observations were made of the surface of the moon during the december 1990 flyby of the earth moon system by the galileo spacecraft this article documents this data set and presents analyses of some of the data the near infrared mapping spectrometer nims investigation obtained 17 separate mosaics of the moon in 408 spectral channels between about 0 7 and 5 2 m the instrument was originally designed to operate in orbit about jupiter and therefore saturates at many spectral channels for most measurement situations at 1 au however sufficient measurements were made of the moon to verify the proper operation of the instrument and to demonstrate its capabilities analysis of these data show that the nims worked as expected and produced measurements consistent with previous ground based telescopic studies these are the first imaging spectrometer measurements of this type from space for the moon and they illustrate several major points concerning this type of observation and about the nims capabilities specifically of major importance are the difference between framing and scanning instruments and the effects of the spacecraft and the scan platform on the performance of such an experiment the science return of subsequent nims and other investigation measurements will be significantly enhanced by the experience and results gained

slope distributions threshold hillslopes and steady state topography digital elevation models of two steady state mountain ranges the olympic mountains om and oregon coast range ocr are used to examine relationships between slope distributions the development of threshold hillslopes and steady state topography plots of drainage area versus slope for these mountain ranges exhibit substantial scatter that complicates comparison of range form to analytical theories and landscape evolution models contour plots of the density of such data reveal an attractor at the scale of the transition from hillslope processes to channel processes and log bin averaging reveals trends that parallel predictions of steady state erosion laws but with different rate laws for five distinct process domains hillslopes valley heads and colluvial bedrock and alluvial valley segments slope histograms computed for 100 km2 areas defined by a 10 10 km grid throughout the om exhibit approximately normal or exponential distributions in areas of active rock uplift and depositional topography respectively local slope distributions in the ocr also tend to be normally distributed but some are left skewed in areas with gentler slopes mean slopes determined both over the above referenced grid and a 10 km diam moving window are relatively invariant in the core of the om in spite of strong contrasts in bedrock erodibility and gradients in long term rock uplift rates in contrast the mean slopes in the ocr parallel latitudinal gradients in rock uplift rates and bedrock erodibility hence the slope distributions in the om and ocr reflect distinct relationships between development of threshold bedrock and soil mantled hillslopes and steady state topography

assessing the long term variability of venus winds at cloud level from virtis venus express abstract the venus express vex mission has been in orbit to venus for more than 4 years now the visible and infrared thermal imaging spectrometer virtis instrument onboard vex observes venus in two channels visible and infrared obtaining spectra and multi wavelength images of the planet that can be used to sample the atmosphere at different altitudes day side images in the ultraviolet range 380 nm are used to study the dynamics of the upper cloud at 66 72 km while night side images in the near infrared 1 74 m map the opacity of the lower cloud deck at 44 48 km here we present a long term analysis of the global atmospheric dynamics at these levels using a large selection of orbits from the virtis m dataset covering 860 earth days that extends our previous work sanchez lavega a et al 2008 geophys res lett 35 l13204 and allows studying the variability of the global circulation at the two altitude levels the atmospheric superrotation is evident with equatorial to mid latitudes westward velocities of 100 and 60 m s 1 in the upper and lower cloud layers these zonal velocities are almost constant in latitude from the equator to 50 s from 50 s to 90 s the zonal winds at both cloud layers decrease steadily to zero at the pole individual cloud tracked winds have errors of 3 10 m s 1 with a mean of 5 m s 1 and the standard deviations for a given latitude of our zonal and meridional winds are 9 m s 1 the zonal winds in the upper cloud change with the local time in a way that can be interpreted in terms of a solar tide the zonal winds in the lower cloud are stable at mid latitudes to the tropics and present variability at subpolar latitudes apparently linked to the activity of the south polar vortex while the upper cloud presents a net meridional motion consistent with the upper branch of a hadley cell with peak velocity v 10 m s 1 at 50 s the lower cloud meridional motions are less organized with some cloud features moving with intense northwards and southwards motions up to v 15 m s 1 but on average with almost null global meridional motions at all latitudes we also examine the long term behavior of the winds at these two vertical layers by comparing our extended wind tracked data with results from previous missions

wind streaks on venus clues to atmospheric circulation magellan images reveal surface features on venus attributed to wind processes sand dunes wind sculpted hills and more than 5830 wind streaks have been identified the streaks serve as local wind vanes representing wind direction at the time of streak formation and allowing the first global mapping of near surface wind patterns on venus wind streaks are oriented both toward the equator and toward the west when streaks associated with local transient events such as impact cratering are deleted the westward component is mostly lost but the equatorward component remains this pattern is consistent with a hadley circulation of the lower atmosphere

precipitation landsliding and erosion across the olympic mountains washington state usa abstract in the olympic mountains of washington state landsliding is the primary surface process by which bedrock and hillslope regolith are delivered to river networks however the relative importance of large earthquakes versus high magnitude precipitation events to the total volume of landslide material transported to valley bottoms remains unknown in part due to the absence of large historical earthquakes to test the hypothesis that erosion is linked to precipitation approximately 1000 landslides were mapped from google earth imagery between 1990 and 2015 along a 15 km wide 85 km long 1250 km2 swath across the range the volume of hillslope material moved by each slide was calculated using previously published area volume scaling relationships and the spatial distribution of landslide volume was compared to mean annual precipitation data acquired from the prism climate group for the period 1981 2010 statistical analysis reveals a significant correlation r 0 55 p

the nature of the near infrared features on the venus night side near infrared images of the venus night side show bright contrast features that move from east to west in the direction of the cloud top atmospheric superrotation recently acquired images of the venus night side along with earlier spectroscopic observations allow identification of the mechanisms that produce these features their level of formation and the wind velocities at those levels the features are detectable only at wavelengths near 1 74 and 2 3 micrometers in narrow atmospheric windows between the co 2 and h 2o bands the brightest features have brightness temperatures near 480 kelvin whereas the darkest features are more than 50 kelvin cooler several factors suggest that this radiation is emitted by hot gases at altitudes below 35 kilometers in the venus atmosphere the feature contrasts are produced as this thermal radiation passes through a higher cooler atmospheric layer that has horizontal variations in transparency the 6 5 day east west rotation period of the features indicates that equatorial wind speeds are near 70 meters per second in this upper layer similar wind speeds have been measured by entry probes and balloons at altitudes between 50 and 55 kilometers in the middle cloud layer the bright features indicate that there are partial clearings in this cloud deck the presence of these clearings could decrease the efficiency of the atmospheric greenhouse that maintains the high surface temperatures on venus

a bulk cloud parameterization in a venus general circulation model a condensing cloud parameterization is included in a super rotating venus general circulation model a parameterization including condensation evaporation and sedimentation of mono modal sulfuric acid cloud particles is described saturation vapor pressure of sulfuric acid vapor is used to determine cloud formation through instantaneous condensation and destruction through evaporation while pressure dependent viscosity of a carbon dioxide atmosphere is used to determine sedimentation rates assuming particles fall at their terminal stokes velocity modifications are described to account for the large range of the reynolds number seen in the venus atmosphere two gcm experiments initialized with 10 ppm equivalent of sulfuric acid are integrated for 30 earth years and the results are discussed with reference to y shaped cloud structures observed on venus the gcm is able to produce an analog of the y shaped cloud structure through dynamical processes alone with contributions from the mean westward wind the equatorial kelvin wave and the mid latitude polar mixed rossby gravity waves the cloud top height in the gcm decreases from equator to pole and latitudinal gradients of cloud top height are comparable to those observed by pioneer venus and venus express and those produced in more complex microphysical models of the sulfur cycle on venus differences between the modeled cloud structures and observations are described and dynamical explanations are suggested for the most prominent differences

surface brightness variations seen by virtis on venus express and implications for the evolution of the lada terra region venus 1 venus express is since april 11 2006 in orbit around venus virtis visible and infrared thermal imaging spectrometer has started only hours after orbit insertion to collect an immense and unique data set of special interest is the wavelength range from 1 1 5 microns which includes the atmospheric windows by averaging several hundred multi spectral images obtained during the mission we have been able to map the surface temperatures for almost the whole southern hemisphere of venus blurring in the clouds limits the spatial resolution to approximately 100 km globally the most exciting and at the same time the most complex task is to retrieve compositional information for the surface of venus from the hyperspectral data obtained by virtis we report here about indication for variations in the surface composition in the lada terra region based on brightness variations mapped from virtis measurements and present some tentative links to the evolution of this region

global maps of venus nightside mean infrared thermal emissions obtained by virtis on venus express one of the striking features about venus atmosphere is its temporal variability and dynamics with a chaotic polar vortex large scale atmospheric waves sheared features and variable winds that depend on local time and possibly orographic features the aim of this research is to combine data accumulated over several years and obtain a global mean state of the atmosphere focusing in the global structure of the clouds using the cloud opacity and upper cloud temperatures we have first produced global maps using the integrated radiance through the infrared atmospheric windows centred around 1 74 m and 2 25 m that show the spatial variations of the cloud opacity in the lower clouds around 44 48 km altitude and also provide an indirect estimation of the possible particle size we have also produced similar global maps using the brightness temperatures seen in the thermal region at 3 8 m and 5 0 m which provide direct indication of the temperatures at the top of the clouds around 60 70 km altitude these maps have been generated using the complete dataset of the visible and infrared thermal imaging spectrometer mapping channel virtis m on board venus express with a wide spatial and long temporal coverage in the period from may 2006 until october 2008 our results provide a global view of the cloud opacity particle size and upper cloud temperatures at both hemispheres showing the main different dynamical regions of the planet the profiles obtained also provide the detailed dependencies with latitude local time and longitude diagnostic of the global circulation flow and dynamics at various altitude layers from about 44 up to 70 km over the surface

middle infrared thermal maps of venus at the time of the galileo encounter images of the disk of venus taken at wavelengths between 8 and 22 micrometers were obtained a few days after the galileo spacecraft s closest approach on 8 february 1990 these images show variations in the thickness of the main h2so4 cloud deck and the overlying temperature structure several features are qualitatively similar to those of earlier observations such as a hot region at the south pole surrounded by a cold collar and brightening toward the lower latitudes where low contrast banding appears the collar does have a northern counterpart that is warmer however equatorial limb darkening is quantitatively similar to that of previous observations fairly constant at wavelengths up to 20 micrometers where limb darkening increases substantially in contrast to what was found in previous observations polar and equatorial limb darkening are nearly the same at most wavelengths a longitudinal variation is observable that is consistent with a wavenumber 2 behavior and a brightness maximum near local midnight

felsic highland crust on venus suggested by galileo near infrared mapping spectrometer data received 2 march 2008 revised 29 july 2008 accepted 18 september 2008 published 31 december 2008 1 we evaluated the spatial variation of venusian surface emissivity at 1 18 mm wavelength and that of near surface atmospheric temperature using multispectral images obtained by the near infrared mapping spectrometer nims on board the galileo spacecraft the galileo nims observed the nightside thermal emission from the surface and the deep atmosphere of venus which is attenuated by scattering from the overlying clouds to analyze the nims data we used a radiative transfer model based on the adding method although there is still an uncertainty in the results owing to the not well known parameters of the atmosphere our analysis revealed that the horizontal temperature variation in the near surface atmosphere is no more than 2 k on the venusian nightside and also suggests that the majority of lowlands likely has higher emissivity compared to the majority of highlands one interpretation for the latter result is that highland materials are generally composed of felsic rocks since formation of a large body of granitic magmas requires water the presence of granitic terrains would imply that venus may have had an ocean and a mechanism to recycle water into the mantle in the past

venus surface thermal emission at 1 μm in virtis imaging observations evidence for variation of crust and mantle differentiation conditions 1 the venus express spacecraft images the nightside thermal emissions using the visible and infrared thermal imaging spectrometer virtis at 1 02 1 10 and 1 18 m thermal emission from the surface is observed the signal is attenuated by scattering and absorption in the dense atmosphere the measured flux at the top of the atmosphere is positively correlated with surface temperature and surface emissivity the surface temperature of venus is relatively well constrained as being mainly a function of altitude with a gradient lesser or equal to the adiabatic lapse rate this study examines the correlation of virtis images showing a signal of the surface at 1 02 m with viewing geometry stray sunlight cloud opacity and topography and applies semiempirical relations to remove their influence the remaining contrast can be either ascribed to surface emissivity or unexpected temperature variations temperature variations due to active volcanism are unlikely to be persistent over the time of observations therefore the mosaic of all processed images is here interpreted in terms of surface emissivity variation the emissivity variation found is correlated with geomorphological features established from magellan synthetic aperture radar images it is generally lower at tessera terrain some but not all volcanic edifices show increased emissivity large lava flows in the lada terra lavinia planitia region also show an increased thermal emission this might indicate a more felsic surface composition of tessera highlands and large scale extrusive volcanism of ultramafic composition

multispectral surface emissivity from virtis on venus express abstract the surface composition of venus is mostly inaccessible to remote observation due to the dense cloud cover there are five spectral windows that show measurable thermal emission from the surface at night the virtis spectrometer on venus express observed three of these windows over much of the southern hemisphere of venus we use these data along with magellan altimetry to map surface emissivity the data are initially processed to correct for instrumental straylight from the dayside of venus and to improve wavelength registration these corrected data are then inverted to emissivity at 1020 1100 and 1180 nm wavelength using lookup tables created by an atmospheric radiative transfer model as in earlier studies we find residual trends of surface emissivity with respect to the magellan altimetry that is used in the model to determine surface temperature and thickness of the atmosphere a new observation is that these trends vary significantly from region to region indicating some lateral variability of atmospheric parameters most likely near surface atmospheric temperature the trends are consistent over hundreds to thousands of km thus it is possible to correct for them heuristically in two regions studied in this paper there are significant deviations from the background emissivity which are associated with some geologic features the high noise in 1100 and 1180 nm maps derived from virtis data result in large uncertainties of spectral shape the virtis instrument was not designed for this task and future observations could provide high signal to noise ratio maps in at least 5 distinct bands diagnostic of major rock types and minerals

elucidating the rate of volcanism on venus detection of lava eruptions using near infrared observations abstract lava eruptions can be observed remotely on venus nightside using a near infrared window at a 1 0 micrometer wavelength i e radiation at this wavelength emitted from the planetary surface traverses through the thick venus atmosphere and clouds due to the strong dependence of the intensity of thermal emission on temperature a hot surface produced by a lava eruption emits intense radiation with the intensity of the excess radiation depending on the surface area and temperature of the lava flow the excess emission from the hot surface is blurred by clouds yet a 1 km2 1500 k basaltic lava lake and a 50 km2 1000 k lava flow are readily detected using this technique rapid cooling of exposed lava results in excess surface radiation that is detectable for just one earth day after the end of an eruption hence short term eruptions are only detectable on the side of the planet where night is occurring eruptions lasting more than half a venus day i e more than about 60 earth days however are detectable across the globe as nighttime occurs sometime during this period for every such event due to limited observational geometries a complete global survey of active volcanos cannot be achieved from earth and in fact only about 10 of short lived major volcanic eruptions are observable alternatively a satellite orbiting high above venus 6 venus radii could detect virtually all short lived nighttime volcanic events or about half the events expected to occur across the globe

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

ice cored drumlins at the surge type glacier bruarjokull iceland a transitional state landform this paper presents data on a glacial landform that to our knowledge has not previously been described in the literature the ice cored drumlin the study area is the forefield of the surge type glacier bruarjokull at the northeastern margin of the vatnajokull ice cap fast iceland based on sedimentological field investigations and aerial photograph interpretation a qualitative model for the formation of ice cored drumlins is proposed the drumlin core consists of stagnant glacier ice from a previous advance and bubbly ice formed by snowdrifts which were incorporated during the most recent advance the 1963 64 surge this advance deposited a mantle of basal till and streamlined the ice cored moraines till deformation and deposition on the drumlin ice core is facilitated by a substratum of low permeability ice cored moraines less

venus surface data extraction from virtis venus express measurements estimation of a quantitative approach nightside emission measurements of the visible and infrared thermal imaging spectrometer virtis on the venus express vex spacecraft were used to estimate the potential for surface data extraction a selection of orbits over the northern hemisphere was performed for footprints that cover different scales of surface elevation variations a correction method was used to remove straylight from the measured spectra that is due to direct sunlight striking the instrument a preliminary radiative transfer calculation technique was applied to simulate venus nightside radiation the basic features of the measured spectra are well reproduced present limitations of the algorithm are discussed the variability of the emission window radiances with respect to cloud opacity and surface elevation is modelled and discussed in direct comparison with the measurements it is demonstrated that a multi spectral analysis in the surface and deep atmosphere window ranges 1 0 2 3 m and the use of radiance ratios are well suited to de cloud the data and to extract surface information from the virtis measurements this method allows a mapping of surface topography and the retrieval of the surface temperature a preliminary topography retrieval at beta regio was performed and compared with magellan radar data differences are possibly due to emissivity variations on the surface

fresh ammonia ice clouds in jupiter i spectroscopic identification spatial distribution and dynamical implications we report the first spectroscopic detection of discrete ammonia ice clouds in the atmosphere of jupiter as discovered utilizing the galileo near infrared mapping spectrometer nims spectrally identifiable ammonia clouds siacs cover less than 1 of the globe as measured in complete global imagery obtained in september 1996 during galileo s second orbit more than half of the most spectrally prominent siacs reside within a small latitudinal band extending from 2 to 7 n latitude just south of the 5 m hot spots the most prominent of these are spatially correlated with nearby 5 m bright hot spots lying 1 5 3 0 of latitude to the north they reside over a small range of relative longitudes on the eastward side of hot spots about 37 of the longitudinal distance to the next hot spot to the east this strong correlation between the positions of hot spots and the most prominent equatorial siacs suggests that they are linked by a common planetary wave good agreement is demonstrated between regions of condensation predicted by the rossby wave model of a j friedson and g s orton 1999 bull am astron assoc31 1155 1156 and the observed longitudinal positions of fresh ammonia clouds relative to 5 m hot spots consistency is also demonstrated between 1 the lifetime of particles as determined by the wave phase speed and cloud width and 2 the sedimentation time for 10 m radius particles consistent with previously reported ammonia particle size by t y brooke et al 1998 icarus136 1 13 a young age two days for most siac cloud particles is indicated to the south the most prominent siacs are located to the northwest of the great red spot in a region where a westward flow of jovian air diverted approximately 10 of latitude northward by the great red spot encounters a large eastward flow siacs have been observed repeatedly by nims at this location during galileo s first four years in jupiter orbit it is speculated that due to the three dimensional interactions of these flows relatively large amounts of ammonia gas are steadily transported from the sub cloud troposphere below the 600 mbar level to the high troposphere nearly continuously forming fresh ammonia ice clouds to the northwest of the great red spot

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

estimating accumulation rates and physical properties of sediment behind a dam englebright lake yuba river northern california 1 studies of reservoir sedimentation are vital to understanding scientific and management issues related to watershed sediment budgets depositional processes reservoir operations and dam decommissioning here we quantify the mass organic content and grain size distribution of a reservoir deposit in northern california by two methods of extrapolating measurements of sediment physical properties from cores to the entire volume of impounded material englebright dam completed in 1940 is located on the yuba river in the sierra nevada foothills a research program is underway to assess the feasibility of introducing wild anadromous fish species to the river upstream of the dam possible management scenarios include removing or lowering the dam which could cause downstream transport of stored sediment in 2001 the volume of sediments deposited behind englebright dam occupied 25 5 of the original reservoir capacity the physical properties of this deposit were calculated using data from a coring campaign that sampled the entire reservoir sediment thickness 6 32 m at six locations in the downstream 3 4 of the reservoir as a result the sediment in the downstream part of the reservoir is well characterized but in the coarse upstream part of the reservoir only surficial sediments were sampled so calculations there are more uncertain extrapolation from one dimensional vertical sections of sediment sampled in cores to entire three dimensional volumes of the reservoir deposit is accomplished via two methods using assumptions of variable and constant layer thickness overall the two extrapolation methods yield nearly identical estimates of the mass of the reservoir deposit of 26 106 metric tons t of material of which 64 7 68 5 is sand and gravel over the 61 year reservoir history this corresponds to a maximum basin wide sediment yield of 340 t km2 yr assuming no contribution from upstream parts of the watershed impounded by other dams the uncertainties and limitations of the estimates of overall sediment quantities are discussed implications for watershed management and future reservoir sedimentation studies are also presented

venus cloud top winds from tracking uv features in venus monitoring camera images 1 to date dynamical observations of the venus clouds have delivered mainly either only short term or long term averaged results with the venus monitoring camera vmc it finally became possible to investigate the global dynamics with a relatively high resolution in space and time on a long term basis our findings from manual cloud feature wind tracking in vmc uv image sequences so far show that the details of the mesospheric dynamics of venus appear to be highly variable although the general rotation of the atmosphere remained relatively stable since mariner 10 more than 30 years ago by now there are indications of short term variations in the general circulation pattern of the venus atmosphere at cloud top level in some cases significant variations in the zonal wind properties occur on a timescale of days in other cases we see rather stable conditions over one atmospheric revolution or longer at cloud top level it remains an interesting question whether the irregularly observed midlatitude jets are indeed variable or simply become shielded from view by higher h2so4 haze layers for varying time intervals winds at latitudes higher than 60 s are still difficult to obtain track because of low contrast and scarcity of features but increasing data is being collected over all it was possible to extend latitudinal coverage of the cloud top winds with vmc observations thermal tides seem to be present in the data but final confirmation still depends on synthesis of visible and infrared thermal imaging spectrometer and vmc observations on night and dayside although poorly resolved meridional wind speed measurements agree mainly with previous observations and with the presence of a hadley cell spanning between equatorial region and about 45 s latitude

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