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Sample records for mars upper thermosphere

  1. Non-thermal hydrogen atoms in the terrestrial upper thermosphere.

    Science.gov (United States)

    Qin, Jianqi; Waldrop, Lara

    2016-12-06

    Model predictions of the distribution and dynamical transport of hydrogen atoms in the terrestrial atmosphere have long-standing discrepancies with ultraviolet remote sensing measurements, indicating likely deficiencies in conventional theories regarding this crucial atmospheric constituent. Here we report the existence of non-thermal hydrogen atoms that are much hotter than the ambient oxygen atoms in the upper thermosphere. Analysis of satellite measurements indicates that the upper thermospheric hydrogen temperature, more precisely the mean kinetic energy of the atomic hydrogen population, increases significantly with declining solar activity, contrary to contemporary understanding of thermospheric behaviour. The existence of hot hydrogen atoms in the upper thermosphere, which is the key to reconciling model predictions and observations, is likely a consequence of low atomic oxygen density leading to incomplete collisional thermalization of the hydrogen population following its kinetic energization through interactions with hot atomic or ionized constituents in the ionosphere, plasmasphere or magnetosphere.

  2. Mars thermospheric scale height: CO Cameron and CO2+ dayglow observations from Mars Express

    Science.gov (United States)

    Stiepen, A.; Gérard, J.-C.; Bougher, S.; Montmessin, F.; Hubert, B.; Bertaux, J.-L.

    2015-01-01

    The CO Cameron (170-270 nm) and CO2+ ultraviolet doublet (298 and 299 nm) emissions have been observed on the Mars dayside with Mars Express Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) instrument in the limb viewing mode. These ultraviolet emissions ultimately arise from the excitation of the neutral atmosphere by solar extreme ultraviolet radiation. We analyze a wide dataset covering the years 2003-2013 to determine the scale height of the thermosphere and its variability. We show under which conditions the neutral thermospheric temperature is derived from the CO Cameron and CO2+ emission topside scale height of the limb profiles. We show that emission scale heights are highly variable, ranging from 8.4 to 21.8 km and analyze possible differences between CO Cameron and CO2+-derived scale heights. These large variations appear to dominate over the long-term control exerted by the solar flux reaching the top of the atmosphere during the SPICAM observing period when solar minimum to moderate conditions prevailed. Solar heating impacting the topside thermosphere scale height is apparently overwhelmed by other forcing processes (e.g. waves and tides) during this observing period. It also appears that the crustal residual magnetic field does not significantly influence the scale height of the thermosphere. Furthermore, our analysis suggests that local variations in the thermospheric scale height and associated temperature are equal to or larger than seasonal-latitudinal variability.

  3. Variability of the Thermosphere and Ionosphere of Mars: MAVEN NGIMS Measurements and Global Model Simulations

    Science.gov (United States)

    Bougher, Stephen; Benna, Mehdi; Jakosky, Bruce; Bell, Jared; Mahaffy, Paul; Olsen, Kirk; Roeten, Kali; Elrod, Meredith

    2016-07-01

    The Mars upper atmosphere, encompassing the thermosphere, ionosphere, and lower portion of the exosphere (~100 to 500 km), constitutes the reservoir that regulates present day escape processes from the planet. In principle, it is possible to constrain the current atmospheric escape rates making use of MAVEN measurements over this reservoir region and at higher altitudes. However, without knowledge of the physics and chemistry operating in this reservoir region and driving its significant variations (e.g., solar cycle, solar rotational, seasonal, and diurnal), it is not possible to reliably extrapolate the results over evolutionary history. The characterization of this thermosphere-ionosphere-exosphere reservoir is therefore one of the major science objectives of the MAVEN mission. Recent thermospheric-ionospheric measurements from MAVEN in-situ (NGIMS: Mahaffy et al., 2015, GRL, 42; Benna et al., 2015, GRL, 42) and remote (IUVS: Jain et al. 2015, GRL, 42) instruments indicate striking variability both spatially and temporally during the MAVEN mission thusfar. The first 16-months of MAVEN NGIMS operations (October 2014 to January 2016) is the focus of our extended study here, including both Deep Dip and Science orbits. For the thermosphere, both NGIMS neutral densities and temperatures are shown to vary significantly on diurnal, seasonal, 27-day, and partial solar cycle timescales. NGIMS neutral densities are used to derive temperature profiles, including exospheric temperatures. Solar driven (periodic) variations are certainly present in the NGIMS neutral structure. However, wave structures (i.e. gravity waves, non-migrating and migrating tides) are also clearly discernable. The extraction of solar driven features requires that at least 11-orbit averages of densities or temperatures must be conducted to remove longitude effects, and to reduce the magnitudes of gravity wave features in order that climatic trends can be identified and examined. For the ionosphere

  4. Empirical model of atomic nitrogen in the upper thermosphere

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    Engebretson, M. J.; Mauersberger, K.; Kayser, D. C.; Potter, W. E.; Nier, A. O.

    1977-01-01

    Atomic nitrogen number densities in the upper thermosphere measured by the open source neutral mass spectrometer (OSS) on Atmosphere Explorer-C during 1974 and part of 1975 have been used to construct a global empirical model at an altitude of 375 km based on a spherical harmonic expansion. The most evident features of the model are large diurnal and seasonal variations of atomic nitrogen and only a moderate and latitude-dependent density increase during periods of geomagnetic activity. Maximum and minimum N number densities at 375 km for periods of low solar activity are 3.6 x 10 to the 6th/cu cm at 1500 LST (local solar time) and low latitude in the summer hemisphere and 1.5 x 10 to the 5th/cu cm at 0200 LST at mid-latitudes in the winter hemisphere.

  5. Zonal winds in the equatorial upper thermosphere: Decomposing the solar flux, geomagnetic activity, and seasonal dependencies

    NARCIS (Netherlands)

    Liu, H.; Lühr, H.; Watanabe, S.; Köhler, W.; Henize, V.; Visser, P.N.A.M.

    2006-01-01

    Using 3 years (2002–2004), over 16,400 orbits of measurements from the accelerometer on board the CHAMP satellite, we have studied the climatology of the equatorial zonal wind in the upper thermosphere. Several main features are noticed. The most prominent one is that the solar flux significantly in

  6. Effects of magnetospheric lobe cell convection on dayside upper thermospheric winds at high latitudes

    Science.gov (United States)

    Zhang, B.; Wang, W.; Wu, Q.; Knipp, D.; Kilcommons, L.; Brambles, O. J.; Liu, J.; Wiltberger, M.; Lyon, J. G.; Häggström, I.

    2016-08-01

    This paper investigates a possible physical mechanism of the observed dayside high-latitude upper thermospheric wind using numerical simulations from the coupled magnetosphere-ionosphere-thermosphere (CMIT) model. Results show that the CMIT model is capable of reproducing the unexpected afternoon equatorward winds in the upper thermosphere observed by the High altitude Interferometer WIND observation (HIWIND) balloon. Models that lack adequate coupling produce poleward winds. The modeling study suggests that ion drag driven by magnetospheric lobe cell convection is another possible mechanism for turning the climatologically expected dayside poleward winds to the observed equatorward direction. The simulation results are validated by HIWIND, European Incoherent Scatter, and Defense Meteorological Satellite Program. The results suggest a strong momentum coupling between high-latitude ionospheric plasma circulation and thermospheric neutral winds in the summer hemisphere during positive IMF Bz periods, through the formation of magnetospheric lobe cell convection driven by persistent positive IMF By. The CMIT simulation adds important insight into the role of dayside coupling during intervals of otherwise quiet geomagnetic activity

  7. Thermal structure of Venus upper atmosphere by a ground-to-thermosphere GCM: a preliminary study

    Science.gov (United States)

    Gilli, G.; Lebonnois, S.; Salmi, L.; Gonzalez-Galindo, F.; Lopez-Valverde, M. A.; Eymet, V.; Forget, F.

    2014-04-01

    We present here preliminary results of the thermal structure of the upper atmosphere of Venus simulated by a ground-to thermosphere General Circulation Model (GCM). The GCM developed at the Laboratoire de Meteorologie Dynamique (LMD) [1] has been recently improved and extended vertically from 100 to 150 km, with the inclusion of the physical processes which mostly contribute to the thermal balance in the mesosphere/thermosphere of Venus (i.e near IR heating by CO2, 15 μm thermal cooling, extreme UV heating, thermal conduction). We also focus on recent Venus Express and ground-based temperature measurements above 100 km, both at daytime and nighttime, and we interpret the observed main features with the help of model simulations. This ongoing study may indicate that both radiative and dynamical effects play a crucial role in determining the thermal structure of those upper layers of Venus atmosphere.

  8. Thermal structure of the upper atmosphere of Venus simulated by a ground-to-thermosphere GCM

    Science.gov (United States)

    Gilli, G.; Lebonnois, S.; González-Galindo, F.; López-Valverde, M. A.; Stolzenbach, A.; Lefèvre, F.; Chaufray, J. Y.; Lott, F.

    2017-01-01

    We present here the thermal structure of the upper atmosphere of Venus predicted by a full self-consistent Venus General Circulation Model (VGCM) developed at Laboratoire de Météorologie Dynamique (LMD) and extended up to the thermosphere of the planet. Physical and photochemical processes relevant at those altitudes, plus a non-orographic GW parameterisation, have been added. All those improvements make the LMD-VGCM the only existing ground-to-thermosphere 3D model for Venus: a unique tool to investigate the atmosphere of Venus and to support the exploration of the planet by remote sounding. The aim of this paper is to present the model reference results, to describe the role of radiative, photochemical and dynamical effects in the observed thermal structure in the upper mesosphere/lower thermosphere of the planet. The predicted thermal structure shows a succession of warm and cold layers, as recently observed. A cooling trend with increasing latitudes is found during daytime at all altitudes, while at nighttime the trend is inverse above about 110 km, with an atmosphere up to 15 K warmer towards the pole. The latitudinal variation is even smaller at the terminator, in agreement with observations. Below about 110 km, a nighttime warm layer whose intensity decreases with increasing latitudes is predicted by our GCM. A comparison of model results with a selection of recent measurements shows an overall good agreement in terms of trends and order of magnitude. Significant data-model discrepancies may be also discerned. Among them, thermospheric temperatures are about 40-50 K colder and up to 30 K warmer than measured at terminator and at nighttime, respectively. The altitude layer of the predicted mesospheric local maximum (between 100 and 120 km) is also higher than observed. Possible interpretations are discussed and several sensitivity tests performed to understand the data-model discrepancies and to propose future model improvements.

  9. Solar Cycle/Seasonal Variations of H, D, H2 and He Distributions and Escape on Mars as Determined by the Mars Thermosphere Global Circulation Model (MTGCM)

    Science.gov (United States)

    Bougher, Stephen

    2005-01-01

    The Mars Thermosphere General Circulation Model (MTGCM) was exercised for Ls = 90 (aphelion) solar minimum, and Ls = 270 perihelion) solar maximum conditions. Simulated MTGCM outputs (i.e. helium density distributions) were compared to those previously observed for Earth and Venus. Winter polar night bulges of helium are predicted on Mars, similar to those observed on the nightside of Venus and in the winter polar regions of Earth. A poster on this research was presented at the European Geophysical Society Meeting (EGS) in 2003. This research paves the way for what might be expected in the polar night regions of Mars during upcoming aerobraking and mapping Campaigns. Lastly, Mars thermosphere (approx. 100-130 km) winter polar warming was observed at high Northern latitudes during the perihelion season, but not at high Southern latitudes during the opposite aphelion season. Presumably, the Mars thermospheric circulation is responsible for the dynamically controlled heating needed to warm polar night temperatures above radiative equilibrium values. Again, MTGCM simulations were conducted for Ls = 90 and Ls = 270 conditions; polar temperatures were examined and found to be much warmer at Northern high latitudes (perihelion) than at Southern high latitudes (aphelion), similar to Mars aerobraking datasets. The Mars thermospheric circulation is found to be stronger during perihelion solstice conditions than during aphelion conditions, owing to both stronger seasonal solar and dust heating during Mars perihelion. An invited talk was given at the Spring AGU 2004 on this research. A forthcoming GRL paper was drafted on this same topic, but not submitted before the termination of this 1-year grant.

  10. Upper thermospheric neutral wind and temperature measurements from an extended spatial field

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, E.M.; Aruliah, A.L.; McWhirter, I.; Yiu, H.C.I.; Charalambous, A. [University College London (United Kingdom). Atmospheric Physics Lab.; McCrea, I. [Rutherford Appleton Lab., Chilton, Didcot (United Kingdom). EISCAT Support Group

    2008-07-01

    First results are presented from a Scanning Doppler Imager (SCANDI) installed at the Nordlysstasjonen optical observatory near Longyearbyen, Svalbard (78.2 N, 15.8 E). Observations of the atomic oxygen 630 nm red line emission, originating in the upper thermosphere at around 250 km, have been used to determine neutral winds and temperatures from multiple zones within an extended spatial field. The instrument utilises all-sky optics to achieve multiple simultaneous measurements, compared to the standard Fabry-Perot Interferometer (FPI) procedure of separate line-of-sight samples within a sequence of narrow angle look directions. SCANDI is colocated with such a standard FPI and comparison of neutral wind velocities between the instruments on the night of 15 March 2007 has revealed detailed and consistent structure in the wind field. Southward meridional wind enhancements of several hundred m/s are observed simultaneously with both instruments, revealing structure on scales not currently considered in thermospheric general circulation models (GCMs). The data from this night also demonstrate the influence of discrete auroral events on thermospheric behaviour. High intensities observed by SCANDI in the presence of auroral arcs coincide with a drop in measured neutral temperatures. This is interpreted as a result of the effective altitude of the 630 nm emission being lowered under conditions of soft auroral precipitation. The optical instruments as a consequence sample a region of lower temperature. This effect has been observed previously with lower thermospheric atomic oxygen emissions at 557.7 nm. The EISCAT Svalbard Radar (ESR) provides ion temperatures and electron densities for the night which confirm the influence of precipitation and heating during the auroral events. The minima of ion temperatures through the pre-midnight period provide a good match to the neutral temperatures measured with SCANDI, and to the colocated FPI temperatures. (orig.)

  11. Electromagnetic energy deposition rate in the polar upper thermosphere derived from the EISCAT Svalbard radar and CUTLASS Finland radar observations

    Directory of Open Access Journals (Sweden)

    H. Fujiwara

    2007-11-01

    Full Text Available From simultaneous observations of the European incoherent scatter Svalbard radar (ESR and the Cooperative UK Twin Located Auroral Sounding System (CUTLASS Finland radar on 9 March 1999, we have derived the height distributions of the thermospheric heating rate at the F region height in association with electromagnetic energy inputs into the dayside polar cap/cusp region. The ESR and CUTLASS radar observations provide the ionospheric parameters with fine time-resolutions of a few minutes. Although the geomagnetic activity was rather moderate (Kp=3+~4, the electric field obtained from the ESR data sometimes shows values exceeding 40 mV/m. The estimated passive energy deposition rates are also larger than 150 W/kg in the upper thermosphere over the ESR site during the period of the enhanced electric field. In addition, enhancements of the Pedersen conductivity also contribute to heating the upper thermosphere, while there is only a small contribution for thermospheric heating from the direct particle heating due to soft particle precipitation in the dayside polar cap/cusp region. In the same period, the CUTLASS observations of the ion drift show the signature of poleward moving pulsed ionospheric flows with a recurrence rate of about 10–20 min. The estimated electromagnetic energy deposition rate shows the existence of the strong heat source in the dayside polar cap/cusp region of the upper thermosphere in association with the dayside magnetospheric phenomena of reconnections and flux transfer events.

  12. Gravity wave effects in the thermosphere during sudden stratospheric warmings and vertical coupling between the lower and upper atmosphere

    Science.gov (United States)

    Yiǧit, Erdal; Medvedev, Alexander S.

    2016-07-01

    Gravity waves are primarily generated in the lower atmosphere, propagate upward, and have profound effects not only in the middle atmosphere but also at much higher altitudes. However, their effects in the upper atmosphere beyond the turbopause ( 105 km) have not been sufficiently studied. Using a general circulating model extending from the lower atmosphere to upper thermosphere and incorporating a whole atmosphere nonlinear parameterization of small-scale GWs developed by Yiǧit et al. (2008)}, we demonstrate that not only GWs penetrate into the thermosphere above the turbopause but also produce substantial dynamical and thermal effects that are comparable to ion drag and Joule heating. During sudden stratospheric warmings, GW propagation in the thermosphere is enhanced by more than a factor of three (Yiǧit and Medvedev, 2012)}, producing appreciable body forcing of up to 600 m s^{-1} day^{-1} around 250-300 km. The resultant impact on the variability of the thermospheric circulation can exceed ± 50% depending on the phase of the sudden warming (Yiǧit et al., 2014)}. References: Yiǧit, E., and A. S. Medvedev (2012), Gravity waves in the thermosphere during a sudden stratospheric warming, Geophys. Res. Lett., 39, L21101, doi:10.1029/2012GL053812. Yiǧit, E., A. D. Aylward, and A. S. Medvedev (2008), Parameterization of the effects of vertically propagating gravity waves for thermosphere general circulation models: Sensitivity study, J. Geophys. Res., 113, D19106, doi:10.1029/2008JD010135. Yiǧit, E., A. S. Medvedev, S. L. England, and T. J. Immel (2014), Simulated vari- ability of the high-latitude thermosphere induced by small-scale gravity waves during a sudden stratospheric warming, J. Geophys. Res. Space Physics, 119, doi:10.1002/2013JA019283.

  13. Global empirical wind model for the upper mesosphere/lower thermosphere. I. Prevailing wind

    Directory of Open Access Journals (Sweden)

    Y. I. Portnyagin

    Full Text Available An updated empirical climatic zonally averaged prevailing wind model for the upper mesosphere/lower thermosphere (70-110 km, extending from 80°N to 80°S is presented. The model is constructed from the fitting of monthly mean winds from meteor radar and MF radar measurements at more than 40 stations, well distributed over the globe. The height-latitude contour plots of monthly mean zonal and meridional winds for all months of the year, and of annual mean wind, amplitudes and phases of annual and semiannual harmonics of wind variations are analyzed to reveal the main features of the seasonal variation of the global wind structures in the Northern and Southern Hemispheres. Some results of comparison between the ground-based wind models and the space-based models are presented. It is shown that, with the exception of annual mean systematic bias between the zonal winds provided by the ground-based and space-based models, a good agreement between the models is observed. The possible origin of this bias is discussed.

    Key words: Meteorology and Atmospheric dynamics (general circulation; middle atmosphere dynamics; thermospheric dynamics

  14. Variability of the thermospheric temperatures of Mars during 9 Martian Years as given by a ground-to-exosphere Global Climate Model

    Science.gov (United States)

    Gonzalez-Galindo, Francisco; Forget, Francois; Garcia-Comas, Maya; Millour, Ehouarn; Lopez-Valverde, Miguel; Montabone, Luca

    2016-07-01

    The temperature of the Martian upper thermosphere is one of the main factors affecting the rate of the different escape to space processes which shape the Martian atmosphere and its long-term evolution. A good knowledge of the variability of this parameter is thus very important in order to gain a deeper understanding of the present-day escape rate and of the evolutive history of Mars. We have used a ground-to-exosphere Global Climate Model, the LMD-MGCM, to simulate the variability of the temperatures at the Martian exobase during the last 9 Martian Years (MY24-MY32, approximately 17 terrestrial years). The simulations include for the first time a realistic day-to-day variability of the UV solar flux. The simulated temperatures are in good agreement with the exospheric temperatures derived from Precise Orbit Determination of Mars Global Surveyor. A significant inter-annual variability of the temperatures, due to both the 11 year solar cycle and the variability of the dust load in the lower atmosphere, is predicted by the model. The variation in the solar output produced by the 27 day solar rotation cycle is seen in the simulated exobase temperatures. We also find that the global dust storms in MY25 and MY28 significantly impact the temperatures at the exobase. These results underline the importance of properly taking into account the dust and solar variabilities to simulate the upper atmosphere of Mars.

  15. The Aeronomy of Mars: Characterization by MAVEN of the Upper Atmosphere Reservoir That Regulates Volatile Escape

    Science.gov (United States)

    Bougher, S. W.; Cravens, T. E.; Grebowsky, J.; Luhmann, J.

    2015-12-01

    The Mars thermosphere-ionosphere-exosphere (TIE) system constitutes the atmospheric reservoir (i.e. available cold and hot planetary neutral and thermal ion species) that regulates present day escape processes from the planet. The characterization of this TIE system, including its spatial and temporal (e.g., solar cycle, seasonal, diurnal, episodic) variability is needed to determine present day escape rates. Without knowledge of the physics and chemistry creating this TIE region and driving its variations, it is not possible to constrain either the short term or long term histories of atmosphere escape from Mars. MAVEN (Mars Atmosphere and Volatile Evolution Mission) will make both in-situ and remote measurements of the state variables of the Martian TIE system. A full characterization of the thermosphere (˜100-250 km) and ionosphere (˜100-400 km) structure (and its variability) will be conducted with the collection of spacecraft in-situ measurements that systematically span most local times and latitudes, over a regular sampling of Mars seasons, and throughout the bottom half of the solar cycle. Such sampling will far surpass that available from existing spacecraft and ground-based datasets. In addition, remote measurements will provide a systematic mapping of the composition and structure of Mars neutral upper atmosphere and coronae (e.g. H, C, N, O), as well as probe lower altitudes. Such a detailed characterization is a necessary first step toward answering MAVEN's three main science questions (see Jakosky et al. 2014, this issue). This information will be used to determine present day escape rates from Mars, and provide an estimate of integrated loss to space throughout Mars history.

  16. Morphological features and variations of temperature in the upper thermosphere simulated by a whole atmosphere GCM

    Directory of Open Access Journals (Sweden)

    H. Fujiwara

    2010-02-01

    Full Text Available In order to illustrate morphological features and variations of temperature in the upper thermosphere, we performed numerical simulations with a whole atmosphere general circulation model (GCM for the solar minimum and geomagnetically quiet conditions in March, June, September, and December. In previous GCMs, tidal effects were imposed at the lower boundaries assuming dominant diurnal and semi-diurnal tidal modes. Since the GCM used in the present study covers all the atmospheric regions, the atmospheric tides with various modes are generated within the GCM. The global temperature distributions obtained from the GCM are in agreement with ones obtained from NRLMSISE-00. In addition, the GCM also represents localised temperature structures which are superimposed on the global day-night distributions. These localised structures, which vary from hour to hour, would be observed as variations with periods of about 2–3 h at a single site. The amplitudes of the 2–3 h variations are significant at high-latitude, while the amplitudes are small at low-latitude. The diurnal temperature variation is more clearly identified at low-latitude than at high-latitude. When we assume the same high-latitude convection electric field in each month, the temperature calculated in the polar cap region shows diurnal variation more clearly in winter than in summer. The midnight temperature maximum (MTM, which is one of the typical low-latitude temperature structures, is also seen in the GCM results. The MTMs in the GCM results show significant day-to-day variation with amplitudes of several 10s to about 150 K. The wind convergence and stream of warm air are found around the MTM. The GCM also represent the meridional wind reversals and/or abatements which are caused due to local time variations of airflow pattern in the low-latitude region.

  17. The High-latitude Electric Potential Disparity and Hemispheric Differences in the Upper Thermospheric Neutral Wind Circulation

    Science.gov (United States)

    Foerster, M.; Haaland, S.; Cnossen, I.

    2014-12-01

    We present statistical studies of both the high-latitude ionospheric potential pattern deduced from long-term observations of the Cluster Electron Drift Instrument (EDI) and upper thermospheric neutral wind circulation patterns in the Northern (NH) and Southern Hemisphere (SH) obtained from accelerometers on board of low-Earth orbiting satellites like CHAMP during about the same time interval. The cross-polar cap potential difference during southward IMF conditions appears to be on average slightly (~7%) larger in the SH compared with the NH, while the neutral wind magnitude and vorticity amplitude are mostly larger in the NH than in the SH, especially during high solar activity conditions. We attribute such behaviour to peculiarities of the hemispheres due to the non-dipolar portions of Earth's main magnetic field that constitute substantial differences between the geomagnetic field configurations of both hemispheres. They cause in particular different magnetic field flux densities in the opposite polar regions and different offsets of the invariant poles with respect to the rotation axis of the Earth. The pole is presently displaced almost twice the distance in the SH compared to the NH, which has substantial implications for the coupled magnetosphere-ionosphere-thermosphere system under the influence of external drivers. To analyse this behaviour, we have run several numerical simulations using the first-principle Coupled Magnetosphere-Ionosphere-Thermosphere (CMIT) model under various seasonal conditions. The survey of both the numerical simulation results and the observations confirm prominent asymmetries between the two hemispheres for these parameters.

  18. Solar Wind Interaction with the Martian Upper Atmosphere at Early Mars/Extreme Solar Conditions

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    Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Combi, M. R.

    2014-12-01

    The investigation of ion escape fluxes from Mars, resulting from the solar wind interaction with its upper atmosphere/ionosphere, is important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0 ~ 300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100 km ~ 5 RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model output fields into the 3-D BATS-R-US Mars multi-fluid MHD (MF-MHD) model (100 km ~ 20 RM) that can simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid MHD model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres. This feature allows us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model output fields are used as the input for the multi-fluid MHD model and the M-GITM is used as input into the AMPS exosphere model. In this study, we present M-GITM, AMPS, and MF-MHD calculations (1-way coupled) for 2.5 GYA conditions and/or extreme solar conditions for present day Mars (high solar wind velocities, high solar wind dynamic pressure, and high solar irradiance conditions, etc.). Present day extreme conditions may result in MF-MHD outputs that are similar to 2.5 GYA cases. The crustal field orientations are also considered in this study. By comparing estimates of past ion escape rates with the current ion loss rates to be returned by the MAVEN spacecraft (2013-2016), we can better constrain the

  19. Upper thermospheric responses to forcing from above and below during 1-10 April 2010: Results from an ensemble of numerical simulations

    Science.gov (United States)

    Hagan, M. E.; Häusler, K.; Lu, G.; Forbes, J. M.; Zhang, X.

    2015-04-01

    In this report we examine the spatial and temporal variability of the quiescent thermosphere leading up to and after the 5 April 2010 geomagnetic disturbance. We attribute the dominant driver of this variability to a combination of tides generated in situ and in the troposphere, stratosphere, and mesosphere. We identify nonmigrating tidal signatures attributable to the latter source that are ubiquitous, persistent, and significant at all thermospheric latitudes. Further, these perturbations underlie the upper atmospheric response to solar geomagnetic disturbances and are measurably altered, along with their migrating counterparts, during the storm. Our investigation is centered on a series of National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model simulations during 1-10 April 2010, including an optimal simulation with lower boundary forcing based on Modern-Era Retrospective Analysis for Research and Application reanalysis data and upper boundary forcing based on satellite and ground magnetometer measurements and the Assimilative Mapping of Ionospheric Electrodynamics procedure and three diagnostic simulations. The differences between the optimal and diagnostic simulations allow us to quantify thermospheric variability attributable to solar geomagnetic forcing and dynamical effects propagating into the thermosphere from below. We find that they can be comparable at high latitudes for some nonmigrating tidal components.

  20. Global response of the upper thermospheric winds to large ion drifts in the Jovian ovals

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    Majeed, T.; Bougher, S. W.; Ridley, A. J.; Waite, J. H.; Gladstone, G. R.; Bell, J. M.

    2016-05-01

    We use our fully coupled 3-D Jupiter Thermosphere General Circulation Model (JTGCM) to quantify processes which are responsible for generating neutral winds in Jupiter's oval thermosphere from 20 µbar to 10-4 nbar self-consistently with the thermal structure and composition. The heat sources in the JTGCM that drive the global circulation of neutral flow are substantial Joule heating produced in the Jovian ovals by imposing high-speed anticorotational ion drifts (~3.5 km s-1) and charged particle heating from auroral processes responsible for bright oval emissions. We find that the zonal flow of neutral winds in the auroral ovals of both hemispheres is primarily driven by competition between accelerations resulting from Coriolis forcing and ion drag processes near the ionospheric peak. However, above the ionospheric peak (<0.01 µbar), the acceleration of neutral flow due to pressure gradients is found to be the most effective parameter impacting zonal winds, competing mainly with acceleration due to advection with minor contributions from curvature and Coriolis forces in the southern oval, while in the northern oval it competes alone with considerable Coriolis forcing. The meridional flow of neutral winds in both ovals in the JTGCM is determined by competition between meridional accelerations due to Coriolis forcing and pressure gradients. We find that meridional flow in the lower thermosphere, near the peak of the auroral ionosphere, is poleward, with peak wind speeds of ~0.6 km s-1 and ~0.1 km s-1 in the southern and northern oval, respectively. The corresponding subsiding flow of neutral motion is ~5 m s-1 in the southern oval, while this flow is rising in the northern oval with reduced speed of ~2 m s-1. We also find that the strength of meridional flow in both auroral ovals is gradually weakened and turned equatorward near 0.08 µbar with wind speeds up to ~250 m s-1 (southern oval) and ~75 m s-1 (northern oval). The corresponding neutral motion in this

  1. Global Response of the Upper Thermosphere to Large Ion Drifts in the Jovian Ovals

    Science.gov (United States)

    Majeed, T.; Bougher, S. W.; Ridley, A. J.; Gladstone, R.; Waite, J. H., Jr.; Bell, J. M.

    2015-12-01

    We use our fully coupled 3-D Jupiter Thermosphere General Circulation Model (JTGCM) to quantify wind processes that are responsible for generating neutral winds in the auroral thermosphere from 20 μbar to 10-4 nbar self-consistently with the thermal structure and compositions. The heat sources in the JTGCM that drive the global circulation of neutral flow are charge particle heating from particle impact of extreme auroral conditions and large amount of Joule heating produced in the Jovian ovals by imposing high speed anticorotational ion drifts up to ~3.5 kms-1. These sources are strongly related to the current system in the equatorial plasma sheet that allows plasma to flow outward from the ionosphere to the magnetosphere in the inner part and return from the magnetosphere to the ionosphere in the outer part. We find that strong pressure gradients are developed in the auroral regions, affecting zonal and meridional winds in addition to local temperature distributions. We also find that the zonal flow of neutral winds in the ovals of both hemispheres is primarily driven by competition between Coriolis forcing and ion drag processes near the ionospheric peak. However, above the ionospheric peak, the acceleration of neutral flow due to pressure gradients is found to be the most effective parameter impacting zonal winds. One of the most important findings of this investigation is that the meridional flow of neutral winds in the Jovian ovals is poleward near the peak of the auroral ionosphere. The strength of this flow is gradually weakened and turned equatorward at the sub-nanobar levels with wind speeds up to ~250 ms-1 in the southern oval and ~75 ms-1 in the northern oval. The corresponding neutral motion in this region is upward with wind speeds up to 4 ms-1 in both ovals. We will discuss the model assumptions, numerical framework and several parameterizations of inputs quantities. Comparisons of key model outputs (e.g. neutral temperatures and wind components

  2. Photodissociation of carbon dioxide in the Mars upper atmosphere

    Science.gov (United States)

    Barth, C. A.

    1974-01-01

    Calculation of the intensity of two of the emissions produced during the dissociative excitation of carbon dioxide in the upper atmosphere of Mars by solar ultraviolet radiation. The calculation tangential column emission rates of the atomic oxygen 2972-A line and the carbon monoxide Cameron bands produced by the photodissociative mechanism are found to be factors of 3 and 10, respectively, smaller than the emission rates observed by Mariner ultraviolet spectrometers.

  3. First detection of the 63 μm atomic oxygen line in the thermosphere of Mars with GREAT/SOFIA

    Science.gov (United States)

    Rezac, L.; Hartogh, P.; Güsten, R.; Wiesemeyer, H.; Hübers, H.-W.; Jarchow, C.; Richter, H.; Klein, B.; Honingh, N.

    2015-08-01

    Context. The Stratospheric Observatory for Infrared Astronomy (SOFIA) with its 2.5 m telescope provides new science opportunities for spectroscopic observations of planetary atmospheres in the far-infrared wavelength range. Aims: This paper presents first results from the 14 May, 2014 observing campaign of the Martian atmosphere at 4.7 THz using the German REceiver for Astronomy at Terahertz frequencies (GREAT) instrument. Methods: The atomic oxygen 63 μm transition, OI, was detected in absorption against the Mars continuum, with a high signal-to-noise ratio (~35). A beam-averaged atomic oxygen from a global circulation model was used as input to the radiative transfer simulations of the observed line area and to obtain a new estimate on the column density using a grid-search method. Results: Minimizing differences between the calculated and observed line intensities in the least-square sense yields an atomic oxygen column density of (1.1 ± 0.2) × 1017 cm-2. This value is about twice as low as predicted by a modern photochemical model of Mars. The radiative transfer simulations indicate that the line forms in the upper atmospheric region over a rather extended altitude region of 70-120 km. Conclusions: For the first time, a far-infrared transition of the atomic oxygen line was detected in the atmosphere of Mars. The absorption depth provides an estimate on the column density, and this measurement provides additional means to constrain the photochemical models in global circulation models and airglow studies. The lack of other means for monitoring the atomic oxygen in the Martian upper atmosphere makes future observations with the SOFIA observatory highly desirable. Appendix A is available in electronic form at http://www.aanda.org

  4. Low upper limit to methane abundance on Mars.

    Science.gov (United States)

    Webster, Christopher R; Mahaffy, Paul R; Atreya, Sushil K; Flesch, Gregory J; Farley, Kenneth A

    2013-10-18

    By analogy with Earth, methane in the Martian atmosphere is a potential signature of ongoing or past biological activity. During the past decade, Earth-based telescopic observations reported "plumes" of methane of tens of parts per billion by volume (ppbv), and those from Mars orbit showed localized patches, prompting speculation of sources from subsurface bacteria or nonbiological sources. From in situ measurements made with the Tunable Laser Spectrometer (TLS) on Curiosity using a distinctive spectral pattern specific to methane, we report no detection of atmospheric methane with a measured value of 0.18 ± 0.67 ppbv corresponding to an upper limit of only 1.3 ppbv (95% confidence level), which reduces the probability of current methanogenic microbial activity on Mars and limits the recent contribution from extraplanetary and geologic sources.

  5. Pushing the upper limit of Rayleigh-scatter Temperatures Retrievals into the Lower Thermosphere Using an Inversion Approach

    Science.gov (United States)

    Bandoro, J.; Sica, R. J.; Argall, S.

    2012-12-01

    An important aspect of solar terrestrial relations is the coupling between the lower and upper atmosphere-ionosphere system. The coupling is evident in the general circulation of the atmosphere, where waves generate in the lower atmosphere play an important role in the dynamics of the upper atmosphere, which feeds back on the lower atmosphere's circulation. To address coupling problems requires measurements over the broadest range of heights possible. A recently developed retrieval method for temperature profiles from Rayleigh-scatter lidar measurements using an inversion approach allows the upward extension of the altitude range of temperature by 10 to 15 km over the conventional method, thus producing the equivalent of increasing the systems power-aperture product by 4 times [1]. The method requires no changes to the lidar's hardware and thus, can be applied to the body of existing measurements. In addition, since the uncertainties of the retrieved temperature profile are found by a Monte Carlo error analysis, it is possible to isolate systematic and random uncertainties to model the effect of each one on the final uncertainty product for the temperature profile. This unambiguous separation of uncertainties was not previously possible as only the propagation of the statistical uncertainties are typically reported. For the Purple Crow Lidar, corrections for saturation (e.g. non-linearity) in the photocount returns, ozone extinction and background removal all contribute to the overall systematic uncertainty. Results of individually varying each systematic correction and the effect on the final temperature uncertainty through Monte Carlo realizations are presented to determine the importance for each one. For example, it was found that treatment of the background correction as a systematic versus statistical uncertainty gave results in agreement with each other. This new method is then applied to measurements obtained by the Purple Crow lidar' Rayleigh

  6. Mapping the Upper Subsurface of MARS Using Radar Polarimetry

    Science.gov (United States)

    Carter, L. M.; Rincon, R.; Berkoski, L.

    2012-01-01

    Future human exploration of Mars will require detailed knowledge of the surface and upper several meters of the subsurface in potential landing sites. Likewise, many of the Planetary Science Decadal Survey science goals, such as understanding the history of Mars climate change, determining how the surface was altered through processes like volcanism and fluvial activity, and locating regions that may have been hospitable to life in the past, would be significantly advanced through mapping of the upper meters of the surface. Synthetic aperture radar (SAR) is the only remote sensing technique capable of penetrating through meters of material and imaging buried surfaces at high (meters to tens-of-meters) spatial resolution. SAR is capable of mapping the boundaries of buried units and radar polarimetry can provide quantitative information about the roughness of surface and subsurface units, depth of burial of stratigraphic units, and density of materials. Orbital SAR systems can obtain broad coverage at a spatial scale relevant to human and robotic surface operations. A polarimetric SAR system would greatly increase the safety and utility of future landed systems including sample caching.

  7. Saturn Variable Thermosphere

    CERN Document Server

    Strobel, Darrell F; Mueller-Wodarg, Ingo

    2016-01-01

    Our knowledge of Saturns neutral thermosphere is far superior to that of the other giant planets due to Cassini Ultraviolet Imaging Spectrograph (UVIS) observations of 15 solar occultations and 26 stellar occultations analyzed to date. These measurements yield H2 as the dominant species with an upper limit on the H mole fraction of 5 %. Inferred temperatures near the lower boundary are ~ 150 K, rising to an asymptotic value of ~ 400K at equatorial latitudes and increasing with latitude to polar values in the range of 550-600 K. The latter is consistent with a total estimated auroral power input of ~ 10TW generating Joule and energetic particle heating of ~ 5-6TW that is more than an order of magnitude greater than solar EUV/FUV heating. This auroral heating would be sufficient to solve the energy crisis of Saturns thermospheric heating, if it can be efficiently redistributed to low latitudes. The inferred structure of the thermosphere yields poleward directed pressure gradients on equipotential surfaces consi...

  8. Low upper limit to methane abundance on Mars

    NARCIS (Netherlands)

    Webster, C.R.; Mahaffy, P.R.; Atreya, S.K.; Flesch, G.J.; Farley, K.A.; MSL Science Team, the

    2013-01-01

    By analogy with Earth, methane in the Martian atmosphere is a potential signature of ongoing or past biological activity. During the past decade, Earth-based telescopic observations reported “plumes” of methane of tens of parts per billion by volume (ppbv), and those from Mars orbit showed localized

  9. Study on the impact of sudden stratosphere warming in the upper mesosphere-lower thermosphere regions using satellite and HF radar - [Article

    CSIR Research Space (South Africa)

    Mbatha, N

    2010-01-01

    Full Text Available The occurrence of sudden stratospheric warming (SSW) excites disturbances in the mesosphere-lower thermospheric (MLT) wind and temperature. Here, researchers have examined the high frequency (HF) radar wind data from the South African National...

  10. Nature of the Venus thermosphere derived from satellite drag measurements (solicited paper)

    Science.gov (United States)

    Keating, G.; Theriot, M.; Bougher, S.

    2008-09-01

    density, scale height, inferred temperature, pressure, and other parameters as a function of altitude. The risk involved in the orbital decay and accelerometer measurements is minimal. We have not lost any spacecraft orbiting Venus or Mars due to unexpected thermospheric drag effects in over 30 years. The Venus Express accelerometer drag experiment is very similar to accelerometer experiments aboard Mars Global Surveyor, Mars Odyssey, and Mars Reconnaissance Orbiter which orbit Mars. The Venus Express drag measurements of the polar region will allow a global empirical model of the thermosphere to emerge. Previous drag measurements have been made principally near the equator. The experiment may help us understand on a global scale, tides, winds, gravity waves, planetary waves, and the damping of waves. Comparisons will be made between low and high latitude results; between the middle and upper atmosphere; and with other instruments that provide information from current and previous measurements. The character of the sharp temperature gradient near the day/night terminator needs to be studied at all latitudes. The cryosphere we discovered on the nightside needs to be studied at high latitudes. The rotating vortex dipole over the North Pole surrounded by a colder "collar" needs to be analyzed to identify how wave activity extends into the polar thermosphere. We have already discovered super-rotation in the equatorial thermosphere, but we need to study 4-day super-rotation at higher latitudes to obtain a global picture of the thermosphere. The super-rotation may affect escape rates and the evolution of the atmosphere. References: [1] Keating, G. M., et al: Venus Thermosphere and Exosphere: First Satellite Drag Measurements of an Extraterrestrial Atmosphere. Science, Vol. 203, No. 4382, 772-774, Feb. 23, 1979. [2] Keating, G. M. and Bougher, S.W.: Isolation of Major Venus Cooling Mechanism and Implications for Earth and Mars, Journal of Geophysical Research, Vol. 97, 4189

  11. Coupled rotational dynamics of Saturn's thermosphere and magnetosphere: a thermospheric modelling study

    Directory of Open Access Journals (Sweden)

    C. G. A. Smith

    2008-05-01

    Full Text Available We use a numerical model of Saturn's thermosphere to investigate the flow of angular momentum from the atmosphere to the magnetosphere. The thermosphere model is driven by Joule heating and ion drag calculated from a simple model of the magnetospheric plasma flows and a fixed model of the ionospheric conductivity. We describe an initial study in which our plasma flow model is fixed and find that this leads to several inconsistencies in our results. We thus describe an improved model in which the plasma flows are allowed to vary in response to the structure of the thermospheric winds. Using this improved model we are able to analyse in detail the mechanism by which angular momentum extracted from the thermosphere by the magnetosphere is replaced by transport from the lower atmosphere. Previously, this transport was believed to be dominated by vertical transport due to eddy viscosity. Our results suggest that transport within the upper atmosphere by meridional winds is a much more important mechanism. As a consequence of this, we find that the rotational structures of the thermosphere and magnetosphere are related in a more complex way than the eddy viscosity model implies. Rather than the thermosphere behaving as a passive component of the system, the thermosphere-magnetosphere interaction is shown to be a two-way process in which rotational structures develop mutually. As an example of this, we are able to show that thermospheric dynamics offer an explanation of the small degree of super-corotation that has been observed in the inner magnetosphere. These results call into question the usefulness of the effective Pedersen conductivity as a parameterisation of the neutral atmosphere. We suggest that a two-parameter model employing the true Pedersen conductivity and the true thermospheric rotation velocity may be a more accurate representation of the thermospheric behaviour.

  12. Non-thermal escape of H2 and OH from the upper atmosphere of Mars

    Science.gov (United States)

    Gacesa, Marko; Kharchenko, Vasili

    2016-10-01

    Two major sources of energetic O atoms in the upper atmosphere of Mars are photochemical production, via dissociative recombination (DR) of O2+ and CO2+ molecular ions, and energizing collisions with fast energetic neutral atoms (ENA) produced by the precipitating solar wind ions. The non-thermal O atoms can either directly escape to space, forming a hot oxygen corona, or participate in collisions with background thermal atmospheric gases, such as H2. In this study we present a theoretical analysis of formation and kinetics of hot OH molecules in the upper atmosphere of Mars, produced in reactions of thermal molecular hydrogen and suprathermal oxygen atoms energized by both DR and ENAs. The non-thermal chemical reaction O + H2(v',j') → H + OH(v',j') is described using recent quantum-mechanical state-to-state cross sections[1], which allow us to predict non-equilibrium distributions of excited rotational and vibrational states (v',j') of OH and expected emission spectra for different geometry and solar activity conditions. A potential consequence is appearance or enhancement of faint Meinel bands in the upper atmosphere of Mars. Moreover, a fraction of produced translationally hot H2 and OH are sufficiently energetic to overcome Mars' gravitational potential and escape into space, contributing to the hot corona. The described non-thermal mechanisms produce estimated total escape fluxes of OH and H2 from dayside of Mars, for low solar activity conditions, equal to about 5×1022 s-1 for OH, or about 0.1% of the total escape rate of atomic O and H, and 1023 s-1 for H2 [2]. If HD molecules are considered instead of H2, the non-thermal mechanisms are about 30 times more efficient than Jeans escape, contribute about 5-10% of the total D escape rate, potentially of interest in atmospheric models of water evolution on Mars.[1] M. Gacesa and V. Kharchenko, J. Chem. Phys. 141, 4324 (2014)[2] M. Gacesa, P. Zhang, V. Kharchenko, Geophys. Res. Lett. 39, L10203 (2012).

  13. Solar wind interaction with Mars' upper atmosphere: Results from 3-D studies using one-way coupling between the Multi-fluid MHD, the M-GITM and the AMPS models

    Science.gov (United States)

    Dong, C.; Bougher, S. W.; Ma, Y.; Toth, G.; Lee, Y.; Nagy, A. F.; Tenishev, V.; Pawlowski, D. J.; Meng, X.; Combi, M. R.

    2013-12-01

    The study of the solar wind interaction with Mars upper atmosphere/ionosphere has triggered a great of interest in recent years. Among the large number of topics in this research area, the investigation of ion escape fluxes has become increasingly important due to its potential impact on the long-term evolution of Mars atmosphere (e.g., loss of water) over its history. In the present work, we adopt the 3-D Mars cold neutral atmosphere profiles (0~300 km) from the newly developed and validated Mars Global Ionosphere Thermosphere Model (M-GITM) and the 3-D hot oxygen profiles (100km~5RM) from the exosphere Monte Carlo model Adaptive Mesh Particle Simulator (AMPS). We apply these 3-D model outputs fields into the 3-D BATS-R-US Mars multi-fluid MHD model (100km~20RM) that can better simulate the interplay between Mars upper atmosphere and solar wind by considering the dynamics of individual ion species. The multi-fluid model solves separate continuity, momentum and energy equations for each ion species (H+, O+, O2+, CO2+). The M-GITM model together with the AMPS exosphere model take into account the effects of solar cycle and seasonal variations on both cold and hot neutral atmospheres, allowing us to investigate the corresponding effects on the Mars upper atmosphere ion escape by using a one-way coupling approach, i.e., both the M-GITM and AMPS model outputs are used as the inputs for the multi-fluid model and M-GITM is used as input into the AMPS exosphere model. The calculations are carried out for selected cases with different nominal solar wind, solar cycle and crustal field orientation conditions. This work has the potential to provide predictions of ion escape rates for comparison to future data to be returned by the MAVEN primary mission (2014-2016) and thereby improve our understanding of present day escape processes. Acknowledgments: The work presented here was supported by NASA grants NNH10CC04C, NNX09AL26G, NSF grant ATM-0535811.

  14. An upper limit on Early Mars atmospheric pressure from small ancient craters

    Science.gov (United States)

    Kite, E. S.; Williams, J.; Lucas, A.; Aharonson, O.

    2012-12-01

    Planetary atmospheres brake, ablate, and disrupt small asteroids and comets, filtering out small hypervelocity surface impacts and causing fireballs, airblasts, meteors, and meteorites. Hypervelocity craters 90% of the kinetic energy of >240 kg iron impactors; Titan's paucity of small craters is consistent with a model predicting atmospheric filtering of craters smaller than 6-8km; and on Venus, craters below ~20 km diameter are substantially depleted. Changes in atmospheric CO2 concentration are believed to be the single most important control on Mars climate evolution and habitability. Existing data requires an early epoch of massive atmospheric loss to space; suggests that the present-day rate of escape to space is small; and offers only limited evidence for carbonate formation. Existing evidence has not led to convergence of atmosphere-evolution models, which must balance poorly understood fluxes from volcanic degassing, surface weathering, and escape to space. More direct measurements are required in order to determine the history of CO2 concentrations. Wind erosion and tectonics exposes ancient surfaces on Mars, and the size-frequency distribution of impacts on these surfaces has been previously suggested as a proxy time series of Mars atmospheric thickness. We will present a new upper limit on Early Mars atmospheric pressure using the size-frequency distribution of 20-100m diameter ancient craters in Aeolis Dorsa, validated using HiRISE DTMs, in combination with Monte Carlo simulations of the effect of paleo-atmospheres of varying thickness on the crater flux. These craters are interbedded with river deposits, and so the atmospheric state they record corresponds to an era when Mars was substantially wetter than the present, probably >3.7 Ga. An important caveat is that our technique cannot exclude atmospheric collapse-reinflation cycles on timescales much shorter than the sedimentary basin-filling time, so it sets an upper limit on the density of a thick

  15. A non-LTE retrieval scheme for sounding the upper atmosphere of Mars in the infrared

    Science.gov (United States)

    Lopez-Valverde, Miguel Angel; García-Comas, Maya; Funke, Bernd; Jimenez-Monferrer, Sergio; Lopez-Puertas, Manuel

    2016-04-01

    Several instruments on board Mars Express have been sounding the upper atmosphere of Mars systematically in a limb geometry in the IR part of the spectrum. Two of them in particular, OMEGA and PFS, performed emission measurements during daytime and detected the strongest IR bands of species like CO2 and CO (Piccialli et al, JGRE, submitted). Similarly on Venus, the instrument VIRTIS carried out observations of CO2 and CO bands at 2.7, 4.3 and 4.7 um at high altitudes (Gilli et al, JGRE, 2009). All these daylight atmospheric emissions respond to fluorescent situations, a case of non-local thermodynamic equilibrum conditions (non-LTE), well understood nowadays using comprehensive non-LTE theoretical models and tools (Lopez-Valverde et al., Planet. Space Sci., 2011). However, extensive exploitation of these emissions has only been done in optically thin conditions to date (Gilli et al, Icarus, 2015) or in a broad range of altitudes if in nadir geometry (Peralta et al, Apj, 2015). Within the H2020 project UPWARDS we aim at performing retrievals under non-LTE conditions including optically thick cases, like those of the CO2 and CO strongest bands during daytime in the upper atmosphere of Mars. Similar effort will also be applied eventually to Venus. We will present the non-LTE scheme used for such retrievals, based on similar efforts performed recently in studies of the Earth's upper atmosphere using data from the MIPAS instrument, on board Envisat (Funke et al., Atmos. Chem. Phys., 2009; Jurado-Navarro, PhD Thesis, Univ. Granada, 2015). Acknowledgemnt: This work is supported by the European Union's Horizon 2020 Programme under grant agreement UPWARDS-633127

  16. Variability of the Martian thermospheric temperatures during the last 7 Martian Years

    Science.gov (United States)

    Gonzalez-Galindo, Francisco; Lopez-Valverde, Miguel Angel; Millour, Ehouarn; Forget, François

    2014-05-01

    The temperatures and densities in the Martian upper atmosphere have a significant influence over the different processes producing atmospheric escape. A good knowledge of the thermosphere and its variability is thus necessary in order to better understand and quantify the atmospheric loss to space and the evolution of the planet. Different global models have been used to study the seasonal and interannual variability of the Martian thermosphere, usually considering three solar scenarios (solar minimum, solar medium and solar maximum conditions) to take into account the solar cycle variability. However, the variability of the solar activity within the simulated period of time is not usually considered in these models. We have improved the description of the UV solar flux included on the General Circulation Model for Mars developed at the Laboratoire de Météorologie Dynamique (LMD-MGCM) in order to include its observed day-to-day variability. We have used the model to simulate the thermospheric variability during Martian Years 24 to 30, using realistic UV solar fluxes and dust opacities. The model predicts and interannual variability of the temperatures in the upper thermosphere that ranges from about 50 K during the aphelion to up to 150 K during perihelion. The seasonal variability of temperatures due to the eccentricity of the Martian orbit is modified by the variability of the solar flux within a given Martian year. The solar rotation cycle produces temperature oscillations of up to 30 K. We have also studied the response of the modeled thermosphere to the global dust storms in Martian Year 25 and Martian Year 28. The atmospheric dynamics are significantly modified by the global dust storms, which induces significant changes in the thermospheric temperatures. The response of the model to the presence of both global dust storms is in good agreement with previous modeling results (Medvedev et al., Journal of Geophysical Research, 2013). As expected, the simulated

  17. Non-thermal production and escape of OH from the upper atmosphere of Mars

    Science.gov (United States)

    Gacesa, M.; Lewkow, N.; Kharchenko, V.

    2017-03-01

    We present a theoretical analysis of formation and kinetics of hot OH molecules in the upper atmosphere of Mars produced in reactions of thermal molecular hydrogen and energetic oxygen atoms. Two major sources of energetic O considered are the photochemical production, via dissociative recombination of O2+ ions, and energizing collisions with fast atoms produced by the precipitating Solar Wind (SW) ions, mostly H+ and He2+ , and energetic neutral atoms (ENAs) originating in the charge-exchange collisions between the SW ions and atmospheric gases. Energizing collisions of O with atmospheric secondary hot atoms, induced by precipitating SW ions and ENAs, are also included in our consideration. The non-thermal reaction O + H2(v, j) → H + OH(v‧, j‧) is described using recent quantum-mechanical state-to-state cross sections, which allow us to predict non-equilibrium distributions of excited rotational and vibrational states (v‧, j‧) of OH and expected emission spectra. A fraction of produced translationally hot OH is sufficiently energetic to overcome Mars' gravitational potential and escape into space, contributing to the hot corona. We estimate its total escape flux from the dayside of Mars for low solar activity conditions at about 1.1 × 1023 s-1 , or about 0.1% of the total escape rate of atomic O and H. The described non-thermal OH production mechanism is general and expected to contribute to the evolution of atmospheres of the planets, satellites, and exoplanets with similar atmospheric compositions.

  18. Statistical analysis of solar wind stream interface induced temperature effects on the upper mesosphere and lower thermosphere over SANAE IV, Antarctica

    Science.gov (United States)

    Ogunjobi, Olakunle; Sivakumar, Venkataraman; William; Sivla, T.

    Using superposed epoch techniques, the TIMED (Thermosphere Ionosphere Mesosphere Energetic and Dynamics) and NOAA 15-18 (National Oceanic and Atmospheric Administration) satellites measurements are used to examine the response of the polar MLT (Mesosphere and Lower Thermosphere) temperature to energetic electron precipitation during solar wind stream interfaces (SI). We first investigate the relationship between the ionospheric absorption from the ground based riometer and degree of energetic electron precipitation from the MEPED (Medium Energy Proton and Electron Detectors) on board the NOAA satellites. By interpolating the energetic electron measurements from MEPED instruments, we can obtain the electron precipitation rates close in time to the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) temperature retrieval. Using measurements sorted over the vicinity of SANAE IV (South Africa National Antarctic Expedition IV), we investigate if there are significant temperature effects in the MLT altitude on SI arrival at Earth. The preliminary analysis indicate that there are no temperature increase below 100 km prior to the SI triggered precipitation; whereas a clear temperature increase is observed at 95 km immediately after the SI impact. The analysis on the SI geophysical properties indicates that an enhanced magnetospheric convection resulting to heating could be responsible for the temperature modification on SI arrival.

  19. Three-dimensional Transient Analysis in the Upper Plenum of MONJU with MARS-LMR

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwi-Lim; Jeong, Jae-Ho; Ha, Kwi-Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    The JAEA had provided a detailed geometrical data of the reactor vessel upper plenum, and time-dependent inlet conditions of the flow rate and temperature at the reactor core top surface for the transient analysis. The KAERI(Korea Atomic Energy Research Institute) had studied a numerical analysis of thermal stratification in an upper plenum of the MONJU using the MARS-LMR code. Three-dimensional analysis results have a good agreement with the experimental data and also show a better estimation than that of the one-dimensional analysis. Three-dimensional thermal hydraulic analyses are implemented in MARS-LMR code to validate the thermal-hydraulic models of the MARS-LMR code and identify important phenomena such as buoyancy effect and thermal stratification. The results of a 3-D analysis show a better estimation than that of a 1-D analysis. In the steady-state calculation, the total flow rate through UFHs is larger than that of the LFHs unlike a result of a 1-D calculation due to a dominant radial-flow instead of an over-flow by a geometrical interruption of an axially located fuel handling system. In the transient calculation, the sodium keeps overflowing an inner barrel during a simulation time of 3600 sec in the 3-D analysis. As a result, sodium over UFHs steadily continues to be cooled in the 3-D analysis. However, a calculated temperature at the 9th node near the top of an inner barrel is lower than an experimental data. It is considered to be caused by a modeling of an over-flow region as one dimensional volume, because the overflow region has a multi-dimensional flow.

  20. Thermospheric Data Assimilation

    Science.gov (United States)

    2016-05-05

    Thermospheric Data Assimilation 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1-0058 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Dr. Tomoko...unlimited 13. SUPPLEMENTARY NOTES Program Manager: Dr. Julie J Moses, AFOSR, 703-696-9586, Julie.moses@us.af.mil 14. ABSTRACT This project...thermosphere-ionosphere first- principles model. An ensemble data assimilation procedure, constructed with the NCAR Data Assimilation Research Testbed

  1. Consistent Static Models of Local Thermospheric Composition Profiles

    CERN Document Server

    Picone, J M; Drob, D P

    2016-01-01

    The authors investigate the ideal, nondriven multifluid equations of motion to identify consistent (i.e., truly stationary), mechanically static models for composition profiles within the thermosphere. These physically faithful functions are necessary to define the parametric core of future empirical atmospheric models and climatologies. Based on the strength of interspecies coupling, the thermosphere has three altitude regions: (1) the lower thermosphere (herein z ~200 km), in which the species flows are approximately uncoupled; and (3) a transition region in between, where the effective species particle mass and the effective species vertical flow interpolate between the solutions for the upper and lower thermosphere. We place this view in the context of current terminology within the community, i.e., a fully mixed (lower) region and an upper region in diffusive equilibrium (DE). The latter condition, DE, currently used in empirical composition models, does not represent a truly static composition profile ...

  2. Winds in the Thermosphere

    Science.gov (United States)

    Killeen, T. L.; Burns, A. G.

    2005-12-01

    T. L. Killeen and A. G. Burns Studies of thermospheric dynamics began in the middle 1960s, when King suggested that winds would flow from the hot afternoon sector into the cooler morning region. Later work showed that winds were also driven by the high latitude ion convection pattern and by waves propagating upwards from the lower atmosphere. Ground based Fabry-Perot Interferometers (FPIs) were soon developed that could measure these winds. These interferometers have been deployed successfully both at a variety of ground based locations and in space. Other types of instruments, such as the DE-FPI, WATS and the WINDII instruments, have been deployed successfully in space. The development of thermospheric general circulation models (GCMs) has also greatly increased our understanding of the dynamics of the thermosphere and the way that these dynamics develop as forcing changes. Recent developments include thermosphere-ionosphere GCMs that are coupled with the magnetosphere and improved empirical wind models. In this presentation we summarize the history of thermospheric dynamics. In addition, we discuss current developments with reference to some new, coupled model results that show a number of unexpected features such as strong vertical gradients of horizontal winds in certain conditions and a complex morphology of the dawn convection pattern. Lastly, we suggest some future directions for investigations of the winds in the thermosphere.

  3. Atomic oxygen in the Martian thermosphere

    Science.gov (United States)

    Stewart, A. I. F.; Alexander, M. J.; Meier, R. R.; Paxton, L. J.; Bougher, S. W.; Fesen, C. G.

    1992-01-01

    Modern models of thermospheric composition and temperature and of excitation and radiative transfer processes are used to simulate the O I 130-nm emission from Mars measured by the Mariner 9 ultraviolet spectrometer. This paper uses the Mars thermospheric general circulation model calculations (MTGCM) of Bougher et al. (1988) and the Monte Carlo partial frequency redistribution multiple scattering code of Meier and Lee (1982). It is found that the decline in atomic oxygen through the daylight hours predicted by the MTGCM cannot be reconciled with the excess afternoon brightness seen in the data. Oxygen concentrations inferred from the data show a positive gradient through the day, in agreement with the original analysis by Strickland et al. (1973). In addition, the data suggest that the oxygen abundance increases toward high southerly latitudes, in contrast with the MTGCM prediction of high values in the Northern Hemisphere. It appears that solar forcing alone cannot account for the observed characteristics of the Martian thermosphere and that wave and tidal effects may profoundly affect the structure, winds, and composition.

  4. Photochemical Escape of Oxygen from Early Mars

    CERN Document Server

    Zhao, Jinjin

    2015-01-01

    Photochemical escape is an important process for oxygen escape from present Mars. In this work, a 1-D Monte-Carlo Model is developed to calculate escape rates of energetic oxygen atoms produced from O2+ dissociative recombination reactions (DR) under 1, 3, 10, and 20 times present solar XUV fluxes. We found that although the overall DR rates increase with solar XUV flux almost linearly, oxygen escape rate increases from 1 to 10 times present solar XUV conditions but decreases when increasing solar XUV flux further. Analysis shows that atomic species in the upper thermosphere of early Mars increases more rapidly than O2+ when increasing XUV fluxes. While the latter is the source of energetic O atoms, the former increases the collision probability and thus decreases the escape probability of energetic O. Our results suggest that photochemical escape be a less important escape mechanism than previously thought for the loss of water and/or CO2 from early Mars.

  5. A superposed epoch study of the effects of solar wind stream interface events on the upper mesospheric and lower thermospheric temperature

    Science.gov (United States)

    Ogunjobi, O.; Sivakumar, V.; Sivla, W. T.

    2014-11-01

    The response of mesosphere and lower thermosphere (MLT) temperature to energetic particle precipitation over the Earth’s polar regions is not uniform due to complex phenomena within the MLT environment. Nevertheless, the modification of MLT temperatures may require an event-based study to be better observed. This work examines the influence of precipitation, triggered by solar wind stream interfaces (SI) event from 2002 to 2007, on polar MLT temperature. We first test the relationship between the ionospheric absorption measured by the SANAE IV (South African National Antarctic Expedition IV) riometer and the layer of energetic particle precipitation from POES (Polar Orbiting Environmental Satellites). The combined particle measurements from POES 15, 16, 17 and 18 were obtained close in time to the pass of the SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) temperature retrieval. Here, a superposed epoch technique is described and implemented to obtain average temperature profiles during SI-triggered particle precipitation. The superposed epoch average shows no significant temperature decrease below 100 km prior to the onset of SI-triggered precipitation, whereas a clear superposed average temperature decrease is observed at 95 km after the SI impact. A case study of SI event also yields similar observations. Results indicate that cooling effects due to the production of mesospheric odd hydrogen might be major contributors to temperature decrease under compressed solar wind stream.

  6. Mars

    CERN Document Server

    Elkins-Tanton, Linda T

    2010-01-01

    Mars exploration has never been more active, and our understanding of the planet is advancing rapidly. New discoveries reveal gullies carved by recent groundwater flow, thick ice deposits protected by rocks and soil even at the equator, and new evidence for lakes and seas in Mars' past. The Martian surface has some of the oldest planetary crust in the solar system, containing clues to conditions in early planets that cannot be obtained elsewhere.Beginning with a discussion of Mars as a planet in orbit, Mars, Revised Edition covers fundamental facts about this planet, including its mass and siz

  7. Response of thermosphere density to high-latitude forcing

    Science.gov (United States)

    Yamazaki, Y.; Kosch, M. J.; Vickers, H.; Sutton, E. K.; Ogawa, Y.

    2014-12-01

    Solar wind-magnetospheric disturbances cause enhancements in the energy input to the high-latitude upper atmosphere through particle precipitation and Joule heating. As the upper atmosphere is heated and expanded during geomagnetically disturbed periods, the neutral density in the thermosphere increases at a fixed altitude. Conversely, the thermosphere contracts during the recovery phase of the disturbance, resulting in a decrease of the density. The main objectives of this study are (1) to determine the morphology of the global thermospheric density response to high-latitude forcing, and (2) to determine the recovery speed of the thermosphere density after geomagnetic disturbances. For (1), we use thermospheric density data measured by the Challenging Minisatellite Payload (CHAMP) satellite during 2000-2010. It is demonstrated that the density enhancement during disturbed periods occurs first in the dayside cusp region, and the density at other regions slowly follows it. The reverse process is observed when geomagnetic activity ceases; the density enhancement in the cusp region fades away first, then the global density slowly goes back to the quiet level. For (2), we analyze EISCAT Svalbard radar and Tromso UHF radar data to estimate thermospheric densities during the recovery phase of geomagnetic disturbances. We attempt to determine the time constant for the density recovery both inside and outside the cusp region.

  8. Mars

    CERN Document Server

    Day, Trevor

    2006-01-01

    Discusses the fundamental facts concerning this mysterious planet, including its mass, size, and atmosphere, as well as the various missions that helped planetary scientists document the geological history of Mars. This volume also describes Mars'' seasons with their surface effects on the planet and how they have changed over time.

  9. Martian upper atmosphere response to solar EUV flux and soft X-ray flares

    Science.gov (United States)

    Jain, Sonal; Stewart, Ian; Schneider, Nicholas M.; Deighan, Justin; Stiepen, Arnaud; Evans, J. Scott; Stevens, Michael H.; Chaffin, Michael S.; Crismani, Matteo; McClintock, William; Montmessin, Franck; Thiemann, E. M.; Eparvier, Frank; Chamberlin, Phillip C.; Jacosky, Bruce

    2016-10-01

    Planetary upper atmosphere energetics is mainly governed by absorption of solar extreme ultraviolet (EUV) radiation. Understanding the response of planetary upper atmosphere to the daily, long and short term variation in solar flux is very important to quantify energy budget of upper atmosphere. We report a comprehensive study of Mars dayglow observations made by the IUVS instrument aboard the MAVEN spacecraft, focusing on upper atmospheric response to solar EUV flux. Our analysis shows both short and long term effect of solar EUV flux on Martian thermospheric temperature. We find a significant drop (> 100 K) in thermospheric temperature between Ls = 218° and Ls = 140°, attributed primarily to the decrease in solar activity and increase in heliocentric distance. IUVS has observed response of Martian thermosphere to the 27-day solar flux variation due to solar rotation.We also report effect of two solar flare events (19 Oct. 2014 and 24 March 2015) on Martian dayglow observations. IUVS observed about ~25% increase in observed brightness of major ultraviolet dayglow emissions below 120 km, where most of the high energy photons (< 10 nm) deposit their energy. The results presented in this talk will help us better understand the role of EUV flux in total heat budget of Martian thermosphere.

  10. Mars

    CERN Document Server

    Payment, Simone

    2017-01-01

    This curriculum-based, fun, and approachable book offers everything young readers need to know to begin their study of the Red Planet. They will learn about the fundamental aspects of the Mars, including its size, mass, surface features, interior, orbit, and spin. Further, they will learn about the history of the missions to Mars, including the Viking spacecraft and the Curiosity and MAVEN rovers. Finally, readers will learn about why scientists think there's a chance that Mars is or was suitable for life. With stunning imagery from NASA itself, readers will have a front seat-view of the missi

  11. Non-thermal production and escape of OH from the upper atmosphere of Mars

    CERN Document Server

    Gacesa, Marko; Kharchenko, Vasili

    2016-01-01

    We present a theoretical analysis of formation and kinetics of hot OH molecules in the upper atmosphere of Mars produced in reactions of thermal molecular hydrogen and energetic oxygen atoms. Two major sources of energetic O considered are the photochemical production, via dissociative recombination of O$_{2}^{+}$ ions, and energizing collisions with fast atoms produced by the precipitating Solar Wind (SW) ions, mostly H$^+$ and He$^{2+}$, and energetic neutral atoms (ENAs) originating in the charge-exchange collisions between the SW ions and atmospheric gases. Energizing collisions of O with atmospheric secondary hot atoms, induced by precipitating SW ions and ENAs, are also included in our consideration. The non-thermal reaction O + H$_2(v,j) \\rightarrow$ H + OH$(v',j')$ is described using recent quantum-mechanical state-to-state cross sections, which allow us to predict non-equilibrium distributions of excited rotational and vibrational states $(v',j')$ of OH and expected emission spectra. A fraction of pr...

  12. Thermospheric hydrogen response to increases in greenhouse gases

    Science.gov (United States)

    Nossal, S. M.; Qian, L.; Solomon, S. C.; Burns, A. G.; Wang, W.

    2016-04-01

    We investigated thermospheric hydrogen response to increase in greenhouse gases and the dependence of this response to solar activity, using a global mean version of the National Center for Atmospheric Research Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model. We separately doubled carbon dioxide (CO2) and methane (CH4) to study the influence of temperature and changes to source species for hydrogen. Our results indicate that both CO2 cooling and CH4 changes to the source species for hydrogen lead to predicted increases in the upper thermospheric hydrogen density. At 400 km, hydrogen increases ~30% under solar maximum and ~25% under solar minimum responding to doubling of CH4, indicating that hydrogen response to the source variation due to CH4 increase is relatively independent of solar activity. On the other hand, hydrogen response to doubling of CO2 highly depends on solar activity. At 400 km, doubling of CO2 results in an ~7% hydrogen increase at solar maximum, whereas it is ~25% at solar minimum. Consequently, at solar maximum, the predicted ~40% increase in atomic hydrogen in the upper thermosphere is primarily due to the source variation as a result of doubling of CH4, whereas at solar minimum, both cooling due to doubling of CO2 and the source variation due to doubling of CH4 have commensurate effects, resulting in an approximate 50% increase in the modeled upper thermospheric hydrogen.

  13. Constraining a Martian general circulation model with the MAVEN/IUVS observations in the thermosphere

    Science.gov (United States)

    Moeckel, Chris; Medvedev, Alexander; Nakagawa, Hiromu; Evans, Scott; Kuroda, Takeshi; Hartogh, Paul; Yiğit, Erdal; Jain, Sonal; Lo, Daniel; Schneider, Nicholas M.; Jakosky, Bruce

    2016-10-01

    The recent measurements of the number density of atomic oxygen by Mars Atmosphere and Volatile EvolutioN/ Imaging UltraViolet Spectrograph (MAVEN/IUVS) have been implemented for the first time into a global circulation model to quantify the effect on the Martian thermosphere. The number density has been converted to 1D volume mixing ratio and this profile is compared to the atomic oxygen scenarios based on chemical models. Simulations were performed with the Max Planck Institute Martian General Circulation Model (MPI-MGCM). The simulations closely emulate the conditions at the time of observations. The results are compared to the IUVS-measured CO2 number density and temperature above 130 km to gain knowledge of the processes in the upper atmosphere and further constrain them in MGCMs. The presentation will discuss the role and importance in the thermosphere of the following aspects: (a) impact of the observed atomic oxygen, (b) 27-day solar cycle variations, (c) varying dust load in the lower atmosphere, and (d) gravity waves.

  14. Unique, Non-Earthlike, Meteoritic Ion Behavior in Upper Atmosphere of Mars

    Science.gov (United States)

    Grebowsky, J. M.; Benna, M.; Plane, J. M. C.; Collinson, G. A.; Mahaffy, P. R.; Jakosky, B. M.

    2017-01-01

    Abstract Interplanetary dust particles have long been expected to produce permanent ionospheric metal ion layers at Mars, as on Earth, but the two environments are so different that uncertainty existed as to whether terrestrial-established understanding would apply to Mars. The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission made the first in situ detection of the continuous presence of Na+, Mg+, and Fe+ at Mars and indeed revealed non-Earthlike features/processes. There is no separation of the light Mg+ and the heavy Fe+ with increasing altitude as expected for gravity control. The metal ions are well-mixed with the neutral atmosphere at altitudes where no mixing process is expected. Isolated metal ion layers mimicking Earths sporadic E layers occur despite the lack of a strong magnetic field as required at Earth. Further, the metal ion distributions are coherent enough to always show atmospheric gravity wave signatures. All features and processes are unique to Mars.

  15. Impact of semidiurnal tidal variability during SSWs on the mean state of the ionosphere and thermosphere

    Science.gov (United States)

    Pedatella, N. M.; Richmond, A. D.; Maute, A.; Liu, H.-L.

    2016-08-01

    Observations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites reveal a global reduction in the zonal and diurnal mean F region peak electron density (NmF2) during sudden stratosphere warmings (SSWs). The present study investigates the source of the global NmF2 decrease by performing numerical experiments with the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-electrodynamics general circulation model. The simulations reveal that the NmF2 reduction coincides with a depletion of thermospheric [O]/[N2], indicating that the NmF2 depletion is related to changes in thermospheric composition during SSWs. Numerical experiments further illustrate that the short-term (˜10 day) enhancement of the migrating semidiurnal solar tide (SW2) during SSWs is the source of the variability in thermospheric composition. In particular, the enhancement of the SW2 during SSWs alters the lower thermosphere zonal mean circulation, leading to a reduction in atomic oxygen in the lower thermosphere. The atomic oxygen reduction propagates into the upper thermosphere through molecular diffusion, leading to a decrease in [O]/[N2] throughout the low- to middle-latitude thermosphere. It is anticipated that the effects of the SW2 on the ionosphere and thermosphere investigated herein will be modulated by SSW related enhancements of the migrating semidiurnal lunar tide (M2). The magnitude of the combined impact of the SW2 and M2 on the ionosphere-thermosphere mean state will depend on the relative phasing of the solar and lunar tides. The results demonstrate that in addition to modulating the low-latitude electrodynamics, tidal variability during SSWs can significantly impact the mean state of the ionosphere and thermosphere.

  16. Mars Atmospheric History Derived from Upper-Atmospheric Structure of 38Ar/36Ar Measured From MAVEN

    Science.gov (United States)

    Jakosky, Bruce; Slipski, Marek; Benna, Mehdi; Mahaffy, Paul; Elrod, Meredith K.; Yelle, Roger; Stone, Shane; Alsaeed, Noora

    2016-10-01

    Measurements of the structure of the Martian upper atmosphere made from MAVEN observations allow us to derive homopause and exobase altitudes in the Mars upper atmosphere and to determine the isotopic fractionation that occurs between them. Fractionation in the ratio of 38Ar/36Ar occurs between the homopause and exobase due to diffusive separation. This fractionation, combined with measurements of the bulk atmospheric ratio, is used to determine the total amount of argon lost to space by pick-up-ion sputtering. Our analysis is based on Rayleigh distillation, modified by replenishment of gas to the atmosphere by outgassing, impact, and crustal weathering. Approximately 80 % of the 36Ar that was ever in the atmosphere has been removed through time. This high value requires that a major fraction of Mars atmospheric gas has been lost to space. It points strongly to loss to space as having been the dominant mechanism driving the transition in Martian climate from an early, warm, wet environment to today's cold, dry, thin atmosphere.

  17. Forecasting Thermosphere Density: an Overview

    Science.gov (United States)

    Bruinsma, S.

    2015-12-01

    Our knowledge of the thermosphere has improved considerably since 2000 thanks to the availability of high-resolution accelerometer inferred densities. Consequently, precision and shortcomings of thermosphere models are better known. Thermosphere density forecast accuracy is limited by: 1) the accuracy of the thermosphere model 2) the solar and geomagnetic activity forecast 3) the quality of the data assimilation system. The precision of semi-empirical thermosphere models is 10-25%. Solar activity forecasts can be accurate up to 5 days. They become less accurate with time, but some proxies are more forecastable than others. Geomagnetic activity forecasting is more problematic, since in most cases storm events cannot be predicted on any time scale. The forecast accuracy is ultimately bounded by the thermosphere model precision and the (varying) degree to which mainly the solar proxy represents EUV heating of the atmosphere. Both errors can be corrected for by means of near real time (nrt) assimilation of satellite drag data, provided that the data is of high quality. At present, only the classified High Accuracy Satellite Drag Model of the Air Force has that capability operationally, even if other prototype nrt models have been developed. Data assimilation significantly improves density forecasts up to 72-hours out; there is no gain for longer periods due to the short memory of the thermosphere system. Only physical models, e.g. TIMEGCM and CTIPe, can in principle reproduce the dynamic changes in density for example during geomagnetic storms. However, accurate information on atmospheric heating is often missing, or not used. When it is, observed and modeled Traveling Atmospheric Disturbances are very similar. Nonmigrating tides and waves propagating from the lower atmosphere cause longitudinal density variations; sources of geophysical noise for semi-empirical models, they can be predicted qualitatively and sometimes quantitatively with physical models. This

  18. Volcanism on Mars controlled by early oxidation of the upper mantle.

    Science.gov (United States)

    Tuff, J; Wade, J; Wood, B J

    2013-06-20

    Detailed information about the chemical composition and evolution of Mars has been derived principally from the SNC (shergottite-nakhlite-chassignite) meteorites, which are genetically related igneous rocks of Martian origin. They are chemically and texturally similar to terrestrial basalts and cumulates, except that they have higher concentrations of iron and volatile elements such as phosphorus and chlorine and lower concentrations of nickel and other chalcophile (sulphur-loving) elements. Most Martian meteorites have relatively young crystallization ages (1.4 billion years to 180 million years ago) and are considered to be derived from young, lightly cratered volcanic regions, such as the Tharsis plateau. Surface rocks from the Gusev crater analysed by the Spirit rover are much older (about 3.7 billion years old) and exhibit marked compositional differences from the meteorites. Although also basaltic in composition, the surface rocks are richer in nickel and sulphur and have lower manganese/iron ratios than the meteorites. This has led to doubts that Mars can be described adequately using the 'SNC model'. Here we show, however, that the differences between the compositions of meteorites and surface rocks can be explained by differences in the oxygen fugacity during melting of the same sulphur-rich mantle. This ties the sources of Martian meteorites to those of the surface rocks through an early (>3.7 billion years ago) oxidation of the uppermost mantle that had less influence on the deeper regions, which produce the more recent volcanic rocks.

  19. A combined solar and geomagnetic index for thermospheric climate.

    Science.gov (United States)

    Mlynczak, Martin G; Hunt, Linda A; Marshall, B Thomas; Russell, James M; Mertens, Christopher J; Thompson, R Earl; Gordley, Larry L

    2015-05-28

    Infrared radiation from nitric oxide (NO) at 5.3 µm is a primary mechanism by which the thermosphere cools to space. The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics satellite has been measuring thermospheric cooling by NO for over 13 years. In this letter we show that the SABER time series of globally integrated infrared power (watts) radiated by NO can be replicated accurately by a multiple linear regression fit using the F10.7, Ap, and Dst indices. This allows reconstruction of the NO power time series back nearly 70 years with extant databases of these indices. The relative roles of solar ultraviolet and geomagnetic processes in determining the NO cooling are derived and shown to vary significantly over the solar cycle. The NO power is a fundamental integral constraint on the thermospheric climate, and the time series presented here can be used to test upper atmosphere models over seven different solar cycles.

  20. Ionosphere-Thermosphere Coupling in Jupiter's Low Latitudes

    Science.gov (United States)

    Stallard, T.; Melin, H.; Johnson, R.; O'Donoghue, J.; Moore, L.; Miller, S.; Tao, C.; Achilleos, N. A.; Smith, C.; Ray, L. C.; Yates, J. N.

    2015-12-01

    One of the leading problems in our understanding of Jupiter's atmosphere, known colloquially as the 'energy crisis', is that the upper atmosphere has global temperatures far in excess of that predicted by solar heating. Unlike the Earth, solar heating has only a small effect on the thermosphere, varying little in temperature with local time, and with equatorial neutrals co-rotating with the planet due to meridional advection. Within the auroral region, ionosphere-thermosphere coupling produces strong flows and results in huge Joule Heating from auroral currents. In this region, the temperature excess can be explained, but Jupiter's fast rotation means that Coriolis forces prevent energy in the poles from transferring equatorward, so there remains no explanation of why low latitudes are overheated by a factor of 3-5 over that predicted by solar heating alone.Despite this anomaly, although the past twenty years has seen a wealth of new data and results in Jupiter's auroral region, studies of the equatorial region have been somewhat limited. This lack of investigation comes partly from the apparent uniform nature of the equatorial region, and partly from the difficulty in observing this region. It is only in the past three years that observers begun to re-examine this region, revealing evidence of complex interactions between the thermosphere and ionosphere, including what appears to be thermospheric weather patterns at a fixed planetary longitudes, stable over two decades; perhaps caused by continuous flows from the auroral region. Here, we introduce our recent research, in order to compare and contrast what has been observed at Jupiter with the more well understood interactions between Earth's ionosphere and thermosphere. We hope that this will open a discussion between the communities that will improve our understanding of the underlying physical processes, as they occur at both planets.

  1. DYNAMO: a Mars upper atmosphere package for investigating solar wind interaction and escape processes, and mapping Martian fields

    DEFF Research Database (Denmark)

    Chassefiere, E.; Nagy, A.; Mandea, M.

    2004-01-01

    DYNAMO is a small multi-instrument payload aimed at characterizing current atmospheric escape, which is still poorly constrained, and improving gravity and magnetic field representations, in order to better understand the magnetic, geologic and thermal history of Mars. The internal structure...... and evolution of Mars is thought to have influenced climate evolution. The collapse of the primitive magnetosphere early in Mars history could have enhanced atmospheric escape and favored transition to the present and climate. These objectives are achieved by using a low periapsis orbit. DYNAMO has been...... proposed in response to the AO released in February 2002 for instruments to be flown as a complementary payload onboard the CNES Orbiter to Mars (MO-07), foreseen to be launched in 2007 in the framework of the French PREMIER Mars exploration program. MO-07 orbital phase 2b (with an elliptical orbit...

  2. TIMED Doppler Interferometer on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite: Data product overview

    Science.gov (United States)

    Niciejewski, R.; Wu, Q.; Skinner, W.; Gell, D.; Cooper, M.; Marshall, A.; Killeen, T.; Solomon, S.; Ortland, D.

    2006-11-01

    The TIMED Doppler Interferometer (TIDI) performs the measurement of upper atmospheric winds on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. This is an optimized single etalon Fabry Perot interferometer that records the slight Doppler shift of individual emission features of the O2 (0,0) atmospheric band. The interferometer operates at a 100% duty cycle obtaining neutral wind altitude profiles on a global basis. The measurements are synoptic and provide an uninterrupted long-term climatological record of the dynamics in the mesosphere and lower thermosphere regions. The data products from TIDI include (1) apparent line of sight winds and integrated brightness, (2) inverted line of sight winds and volume emission rate, and (3) inverted horizontal neutral wind fields on an evenly spaced track angle/altitude grid. The data products demonstrate an interannual variability in the tidal structure of the mesosphere and the lower thermosphere and an inherent daily geophysical variance.

  3. Development of the Non-Hydrostatic Jupiter Global Ionosphere Thermosphere Model (J-GITM): Status and Current Simulations

    Science.gov (United States)

    Bougher, Stephen; Ridley, Aaron; Majeed, Tariq; Waite, J. Hunter; Gladstone, Randy; Bell, Jared

    2016-07-01

    The primary objectives for development and validation of a new 3-D non-hydrostatic model of Jupiter's upper atmosphere is to improve our understanding of Jupiter's thermosphere-ionosphere-magnetosphere system and to provide a global context within which to analyze the data retrieved from the new JUNO mission. The new J-GITM model presently incorporates the progress made on the previous Jupiter-TGCM code (i.e. key parameterizations, ion-neutral chemistry, IR cooling) while also employing the non-hydrostatic numerical core of the Earth Global Ionosphere-Thermosphere Model (GITM). The GITM numerical framework has been successfully applied to Earth, Mars, and Titan (see Ridley et al. [2006], Bougher et al. [2015], Bell [2008, 2010]). Moreover, it has been shown to simulate the effects of strong, localized heat sources (such as joule heating and auroral heating) more accurately than strictly hydrostatic GCMs (Deng et al. [2007, 2008]). Thus far, in the J-GITM model development and testing, model capability has been progressively augmented to capture the neutral composition (e.g. H, H2, He major species), 3-component neutral winds, and thermal structure, as well as the ion composition (H3+, H2+, and H+ among others) above 250 km. Presently, J-GITM: (a) provides an interactive calculation for auroral particle precipitation (i.e. heating, ionization), an improvement over the static formulation used previously in the J-TGCM (Bougher et al., 2005; Majeed et al., 2005, 2009, 2015); (b) self-consistently calculates an ionosphere using updated ion-neutral chemistry, ion dynamics, and electron transport; (c) simulates the chemistry that forms key hydrocarbons at the base of the thermosphere, focusing on CH4, C2H2, and C2H6; (d) allows the production of H3+, CH4, C2H2, and C2H6 to modify the global thermal balance of Jupiter through their non-LTE radiative cooling; (e) provides a calculation of H2 vibrational chemistry to regulate H+ densities; and (f) uses the improved

  4. Space Weather at Mars: 3-D studies using one-way coupling between the Multi-fluid MHD, M-GITM and M-AMPS models

    Science.gov (United States)

    Dong, Chuanfei

    This dissertation presents numerical simulation results of the solar wind interaction with the Martian upper atmosphere by using three comprehensive 3-D models: the Mars Global Ionosphere Thermosphere Model (M-GITM), the Mars exosphere Monte Carlo model Adaptive Mesh Particle Simulator (M-AMPS), and the BATS-R-US Mars multi-fluid MHD (MF-MHD) model. The coupled framework has the potential to provide improved predictions for ion escape rates for comparison with future data to be returned by the MAVEN mission (2014-2016) and thereby improve our understanding of present day escape processes. Estimates of ion escape rates over Mars history must start from properly validated models that can be extrapolated into the past. This thesis aims to build a model library for the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, which will thus enhance the science return from the MAVEN mission. In this thesis, we aim to address the following four main scientific questions by adopting the one-way coupled framework developed here: (1) What are the Martian ion escape rates at the current epoch and ancient times? (2) What controls the ion escape processes at the current epoch? How are the ion escape variations connected to the solar cycle, crustal field orientation and seasonal variations? (3) How do the variable 3-D cold neutral thermosphere and hot oxygen corona affect the solar wind-Mars interaction? (4) How does the Martian atmosphere respond to extreme variations (e.g., ICMEs) in the solar wind and its interplanetary environment? These questions are closely related to the primary scientific goals of NASA's MAVEN mission and European Space Agency's Mars Express (MEX) mission. We reasonably answer all these four questions at the end of this thesis by employing the one-way coupled framework and comparing the simulation results with both MEX and MAVEN observational data.

  5. Resistive Heating in Saturn's Thermosphere

    Science.gov (United States)

    Vriesema, Jess W.; Koskinen, Tommi; Yelle, Roger V.

    2016-10-01

    The thermospheres of the jovian planets are several times hotter than solar heating alone can account for. On Saturn, resistive heating appears sufficient to explain these temperatures in auroral regions, but the particular mechanism(s) responsible for heating the lower latitudes remains unclear. Smith et al. (2005) suggested that electrodynamics of the equatorial region—particularly resistive heating caused by strong electrojet currents—might explain the observed temperatures at low latitudes. Müller-Wodarg et al. (2006) found that their circulation model could reproduce low-latitude temperatures only when they included resistive heating at the poles and applied a uniform, generic heating source globally. Smith et al. (2007) concluded that heating at the poles leads to meridional circulation that cools low latitudes and argued that in-situ heating is required to explain the temperatures at low latitudes.Resistive heating at low latitudes, arising from enhanced current generation driven by thermospheric winds, is a potentially important in-situ heating mechanism. Ion drag caused by low-latitude electrodynamics can modify global circulation and meridional transport of energy. We present an axisymmetric, steady-state formulation of wind-driven electrodynamics to investigate these possibilities throughout Saturn's thermosphere. At present, we assume a dipole magnetic field and neglect any contributions from the magnetosphere. We use ion mixing ratios from the model of Kim et al. (2014) and the observed temperature-pressure profile from Koskinen et al. (2015) to calculate the generalized conductivity tensor as described by Koskinen et al. (2014). Our model solves the coupled equations for charge continuity and Ohm's law with tensor conductivity while enforcing zero current across the boundaries. The resulting partial differential equation is solved for the current density throughout the domain and used to calculate the net resistive heating rate. We demonstrate

  6. Cooling of the Martian thermosphere by CO$_2$ radiation and gravity waves: An intercomparison study with two general circulation models

    CERN Document Server

    Medvedev, Alexander S; Yiğit, Erdal; Feofilov, Artem G; Forget, François; Hartogh, Paul

    2015-01-01

    Observations show that the lower thermosphere of Mars ($\\sim$100--140 km) is up to 40 K colder than the current general circulation models (GCMs) can reproduce. Possible candidates for physical processes missing in the models are larger abundances of atomic oxygen facilitating stronger CO$_2$ radiative cooling, and thermal effects of gravity waves. Using two state-of-the-art Martian GCMs, the Laboratoire de M\\'et\\'eorologie Dynamique and Max Planck Institute models that self-consistently cover the atmosphere from the surface to the thermosphere, these physical mechanisms are investigated. Simulations demonstrate that the CO$_2$ radiative cooling with a sufficiently large atomic oxygen abundance, and the gravity wave-induced cooling can alone result in up to 40 K colder temperature in the lower thermosphere. Accounting for both mechanisms produce stronger cooling at high latitudes. However, radiative cooling effects peak above the mesopause, while gravity wave cooling rates continuously increase with height. A...

  7. Thermospheric emissions of the early Earth

    Science.gov (United States)

    Bernard, D.; Barthélémy, M.; Gronoff, G.; Ménager, H.; Lilensten, J.

    2012-09-01

    The aim of this work is to examine the thermospheric emission of the Earth over its history. In this first step, we adapt a kinetic transport code developed for different planets of the Solar System to the first atmosphere of the Earth. We take into account the possible changes in the solar emission spectrum to compute the diurnal ionizations, excitations and dissociations. We deduce a thermospheric spectrum averaged over the planet. The effect of solar wind electron precipitation is also considered.

  8. High time resolution measurements of the thermosphere from Fabry-Perot Interferometer measurements of atomic oxygen

    Directory of Open Access Journals (Sweden)

    E. A. K. Ford

    2007-06-01

    Full Text Available Recent advances in the performance of CCD detectors have enabled a high time resolution study of the high latitude upper thermosphere with Fabry-Perot Interferometers (FPIs to be performed. 10-s integration times were used during a campaign in April 2004 on an FPI located in northern Sweden in the auroral oval. The FPI is used to study the thermosphere by measuring the oxygen red line emission at 630.0 nm, which emits at an altitude of approximately 240 km. Previous time resolutions have been 4 min at best, due to the cycle of look directions normally observed. By using 10 s rather than 40 s integration times, and by limiting the number of full cycles in a night, high resolution measurements down to 15 s were achievable. This has allowed the maximum variability of the thermospheric winds and temperatures, and 630.0 nm emission intensities, at approximately 240 km, to be determined as a few minutes. This is a significantly greater variability than the often assumed value of 1 h or more. A Lomb-Scargle analysis of this data has shown evidence of gravity wave activity with waves with short periods. Gravity waves are an important feature of mesosphere-lower thermosphere (MLT dynamics, observed using many techniques and providing an important mechanism for energy transfer between atmospheric regions. At high latitudes gravity waves may be generated in-situ by localised auroral activity. Short period waves were detected in all four clear nights when this experiment was performed, in 630.0 nm intensities and thermospheric winds and temperatures. Waves with many periodicities were observed, from periods of several hours, down to 14 min. These waves were seen in all parameters over several nights, implying that this variability is a typical property of the thermosphere.

  9. The Split-field Etalon Doppler Imager (SEDI) - A Compact Thermosphere Wind Profiler

    Science.gov (United States)

    Marchant, A.; Whalen, S.; Stromberg, E. M.; Swenson, C.; Fish, C. S.

    2012-12-01

    The dynamics of the Earth's thermosphere remains an important target for scientific exploration. The primary energy input is solar EUV but during solar events additional energy is deposited into the high-latitude thermosphere in the form of Joule heating and particle precipitation, driving global changes in thermosphere temperature profiles and circulation. Thermosphere wind and temperature profiles are important factors for understanding the dynamic response of the earth system to solar storms, for building and maintaining global weather and climate models, and for making operational space weather predictions. We report progress in miniaturized sensor technology for orbital monitoring of wind and neutral temperature profiles in the upper thermosphere, 200 - 350 km. These profiles are sensed using the atomic oxygen airglow at 630.0 nm. The split-field etalon Doppler imager (SEDI) focuses forward and aft scenes of the earth limb onto a single EMCCD focal plane through a single Fabry-Perot etalon (Figure 1). The size of the SEDI optical system is 14 x 18 x 7 cm. The instrument has no moving parts and is easily packaged in a 6U CubeSat. Strips of the dual interferogram are analyzed with respect to fringe width and radial phase to yield profiles of the neutral temperature and Doppler shift. Instrument calibration is maintained on-orbit using the 630.4 nm reference line from a neon glow lamp. The prediction of Doppler sensitivity vs. tangent height against the limb is plotted in Figure 2 for a profiling resolution of 5 km. Forward-view Doppler profiles are combined with aft-view profiles collected approximately 5 minutes later to create localized 2D wind profiles. A constellation of SEDI CubeSats could provide global monitoring of the thermosphere wind field and its dynamics.; Figure 1. Layout of the SEDI instrument. ; Figure 2. Doppler sensitivity of the SEDI instrument.

  10. Global simulation of UV atmospheric emissions on Mars

    Science.gov (United States)

    González-Galindo, Francisco; Ángel López-Valverde, Miguel; Forget, Francois; Montmessin, Franck; Stiepen, Arnaud

    2016-04-01

    Mars UV atmospheric emissions such as the CO2+ UV doublet, the CO Cameron bands (both in the dayside) and the NO bands (in the nightside) are systematically observed by SPICAM on board Mars Express and IUVS on board MAVEN. The study of these atmospheric emissions allows the determination of the temperature and density in the Martian upper atmosphere, and helps to constrain the thermospheric circulation. While different models have been developed to study these atmospheric emissions, most of them are one dimensional and make a number of assumptions concerning the underlying neutral atmosphere and ionosphere. Within the H2020 project UPWARDS we aim at including models of these atmospheric emissions into a state-of-the-art Global Climate Model for the Martian atmosphere, the LMD-MGCM. This will allow for a self-consistent description of these atmospheric emissions and for the characterizion of their different variability sources. Comparisons with observations will allow to retrieve information about the temperature and density in the Martian upper atmosphere. Here we will present the first results concerning the simulation of these UV emissions and the first comparisons with observations. Acknowledgemnt: This work is supported by the European Union's Horizon 2020 Programme under grant agreement UPWARDS-633127

  11. He Bulge Detection by MAVEN Neutral Gas and Ion Mass Spectrometer (NGIMS) in the Upper Atmosphere of Mars

    Science.gov (United States)

    Elrod, Meredith; Bougher, Stephen; Benna, Mehdi; Yelle, Roger; Jakosky, Bruce; Bell, Jared; Mahaffy, Paul; Stone, Shane

    2016-07-01

    Studies of the Venusian atmospheres have demonstrated enhanced He densities at high latitudes and on the night-side detections. To determine if Mars has a similar enhanced He 'bulge' in the same region, we compared several periapsis passes from night to dayside. The first six weeks of the MAVEN prime mission had periapsis at high latitudes on the night-side, followed by the next three months at mid latitudes on the dayside moving to low latitudes on the night-side. In addition to its normal orbit, which has a periapsis of approximately 150 km, MAVEN conducts a few deep dip orbits where the spacecraft has a periapsis closer to 125km. The first deep dip was at dusk at mid latitudes, the second at noon at the equator, with the third going from dawn to night in the southern hemisphere. Initial analysis of the Neutral Gas and Ion Mass Spectrometer (NGIMS) closed source data from all orbits with good pointing revealed an enhanced He density on the night-side orbits and a decreased He density on the dayside. This enhancement of He demonstrates a bulge at Mars that will continue to be explored over the course of the mission.

  12. Martian thermosphere scale height from SPICAM dayglow measurements

    Science.gov (United States)

    Stiepen, A.; Gérard, J.-C.; Bougher, S.; Montmessin, F.

    2014-04-01

    We analyze the ultraviolet dayglow in the atmosphere of Mars through CO2+ and CO Cameron emissions. These emissions are accumulated on a large dataset of dayside grazing limb performed by the Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) instrument on board the Mars Express spacecraft. The temperature of the Martian upper atmosphere can be retrieved from these limb emission profiles. We present discussion on the validity domain for such retrieval. We also show evidence for local (spatial and temporal) variability in the scale height of the atmosphere at the altitude of these emissions.

  13. Multi-fluid MHD Study of the Solar Wind Interaction with Mars' Upper Atmosphere during the 2015 March 8th ICME Event

    Science.gov (United States)

    Dong, C.; Ma, Y.; Bougher, S. W.; Toth, G.; Nagy, A. F.; Halekas, J. S.; Dong, Y.; Curry, S.; Luhmann, J. G.; Brain, D. A.; Connerney, J. E. P.; Espley, J. R.; Mahaffy, P. R.; Benna, M.; McFadden, J. P.; Mitchell, D. L.; DiBraccio, G. A.; Lillis, R. J.; Jakosky, B. M.; Grebowsky, J. M.

    2015-12-01

    The 3-D Mars multi-fluid BATS-R-US MHD code is used to study the solar wind interaction with the Martian upper atmosphere during the 2015 March 8th interplanetary coronal mass ejection (ICME). We studied four steady-state cases, corresponding to three major ICME phases: pre-ICME phase (Case 1), sheath phase (Cases 2--3), and ejecta phase (Case 4). Detailed data-model comparisons demonstrate that the simulation results are in good agreement with Mars Atmosphere and Volatile EvolutioN (MAVEN) measurements, indicating that the multi-fluid MHD model can reproduce most of the features observed by MAVEN, thus providing confidence in the estimate of ion escape rates from its calculation. The total ion escape rate is increased by an order of magnitude, from 2.05×1024 s-1 (pre-ICME phase) to 2.25×1025 s-1 (ICME sheath phase), during this time period. The calculated ion escape rates were used to examine the relative importance of the two major ion loss channels from the planet: energetic pickup ion loss through the dayside plume and cold ionospheric ion loss through the nightside plasma wake region. We found that the energetic pickup ions escaping from the dayside plume could be as much as ~23% of the total ion loss prior to the ICME arrival. Interestingly, the tailward ion escape rate is significantly increased at the ejecta phase, leading to a reduction of the dayside ion escape to ~5% of the total ion loss. Under such circumstance, the cold ionospheric ions escaping from the plasma wake comprise the majority of the ion loss from the planet. Furthermore, by comparing four simulation results along the same MAVEN orbit, we note that there is no significant variation in the Martian lower ionosphere. Finally, both bow shock and magnetic pileup boundary (BS, MPB) locations are decreased from (1.2 RMars, 1.57 RMars) at the pre-ICME phase to (1.16 RMars, 1.47 RMars) respectively during the sheath phase along the dayside Sun-Mars line. MAVEN has provided a great opportunity to

  14. Middle atmosphere dynamical sources of the semiannual oscillation in the thermosphere and ionosphere

    Science.gov (United States)

    Jones, M.; Emmert, J. T.; Drob, D. P.; Siskind, D. E.

    2017-01-01

    The strong global semiannual oscillation (SAO) in thermospheric density has been observed for five decades, but definitive knowledge of its source has been elusive. We use the National Center of Atmospheric Research thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) to study how middle atmospheric dynamics generate the SAO in the thermosphere-ionosphere (T-I). The "standard" TIME-GCM simulates, from first principles, SAOs in thermospheric mass density and ionospheric total electron content that agree well with observed climatological variations. Diagnosis of the globally averaged continuity equation for atomic oxygen ([O]) shows that the T-I SAO originates in the upper mesosphere, where an SAO in [O] is forced by nonlinear, resolved-scale variations in the advective, net tidal, and diffusive transport of O. Contrary to earlier hypotheses, TIME-GCM simulations demonstrate that intra-annually varying eddy diffusion by breaking gravity waves may not be the primary driver of the T-I SAO: A pronounced SAO is produced without parameterized gravity waves.

  15. DYNAMO: a Mars upper atmosphere package for investigating solar wind interaction and escape processes, and mapping Martian fields

    DEFF Research Database (Denmark)

    Chassefiere, E.; Nagy, A.; Mandea, M.

    2004-01-01

    DYNAMO is a small multi-instrument payload aimed at characterizing current atmospheric escape, which is still poorly constrained, and improving gravity and magnetic field representations, in order to better understand the magnetic, geologic and thermal history of Mars. The internal structure....... Ultraviolet remote sensing is an essential complement to characterize high, tenuous, layers of the atmosphere. One Martian year of operation, with about 5,000 low passes, should allow DYNAMO to map in great detail the residual magnetic field, together with the gravity field. Additional data on the internal...... structure will be obtained by mapping the electric conductivity, sinergistically with the NETLANDER magnetic data. Three options have been recommended by the International Science and Technical Review Board (ISTRB), who met on July 1st and 2nd, 2002. One of them is centered on DYNAMO. The final choice...

  16. Characterizing the thermosphere of HD209458b with UV transit observations

    CERN Document Server

    Koskinen, T T; Lavvas, P; Lewis, N K

    2010-01-01

    Transmission spectroscopy at UV wavelengths is a rich and largely unexplored source of information about the upper atmospheres of extrasolar planets. So far, UV transit observations have led to the detection of atomic hydrogen, oxygen and ionized carbon in the upper atmosphere of HD209458b. The interpretation of these observations is controversial - it is not clear if the absorption arises from an escaping atmosphere interacting with the stellar radiation and stellar wind, or the thermosphere inside the Roche lobe. Here we introduce an empirical model that can be used to analyze UV transit depths of extrasolar planets and use it to interpret the transits of HD209458b in the H Ly alpha and the OI triplet emission lines. The results indicate that the mean temperature of the thermosphere is 8,000-11,000 K and that the H2/H dissociation front is located at pressures between 0.1-1 microbar, which correspond to an altitude of 1.1 Rp. The upper boundary of the model thermosphere is located at altitudes between 2.7-3...

  17. Marshall Engineering Thermosphere Model, Version MET-2007

    Science.gov (United States)

    Suggs, R. J.; Suggs, R. M.

    2017-01-01

    The region of the Earth's atmosphere between about 90 and 500 km altitude is known as the thermosphere, while the region above about 500 km is known as the exosphere. For space vehicle operations, the neutral atmosphere in these regions is significant. Even at its low density, it produces torques and drags on vehicles and affects orbital lifetimes. The thermosphere density above 100 km altitude also modulates the flux of trapped radiation and orbital debris. Atomic oxygen at orbital altitudes is important because it can erode and chemically change exposed vehicle surfaces.

  18. Equinoctial transitions in the ionosphere and thermosphere

    Directory of Open Access Journals (Sweden)

    A. V. Mikhailov

    Full Text Available Equinoctial summer/winter transitions in the parameters of the F2-region are analyzed using ground-based ionosonde and incoherent scatter observations. Average transition from one type of diurnal NmF2 variation to another takes 20–25 days, but cases of very fast (6–10 days transitions are observed as well. Strong day-time NmF2 deviations of both signs from the monthly median, not related to geomagnetic activity, are revealed for the transition periods. Both longitudinal and latitudinal variations take place for the amplitude of such quiet time NmF2 deviations. The summer-type diurnal NmF2 variation during the transition period is characterized by decreased atomic oxygen concentration [O] and a small equatorward thermospheric wind compared to winter-type days with strong poleward wind and increased [O]. Molecular N2 and O2 concentrations remain practically unchanged in such day-to-day transitions. The main cause of the F2-layer variations during the transition periods is the change of atomic oxygen abundance in the thermosphere related to changes of global thermospheric circulation. A possible relationship with an equinoctial transition of atomic oxygen at the E-region heights is discussed.

    Key words. Atmospheric composition and structure (thermosphere – composition and chemistry – Ionosphere (ionosphere- atmosphere interactions; ionospheric disturbances

  19. Sixth International Workshop on the Mars Atmosphere: Modelling and Observations

    Science.gov (United States)

    Forget, F.; Millour, M.

    2017-01-01

    The scope of this workshop is to bring together experts in observations and modelling of the present and past Mars climate systems and discuss the nature of the atmospheric circulation and the photochemistry (up to the thermosphere), the dust cycle, the water cycle (vapor, clouds and frost) and the carbon dioxide cycle (polar caps).

  20. Operational Data Reduction Procedure for Determining Density and Vertical Structure of the Martian Upper Atmosphere from Mars Global Surveyor Accelerometer Measurements

    Science.gov (United States)

    Cancro, George J.; Tolson, Robert H.; Keating, Gerald M.

    1998-01-01

    The success of aerobraking by the Mars Global Surveyor (MGS) spacecraft was partly due to the analysis of MGS accelerometer data. Accelerometer data was used to determine the effect of the atmosphere on each orbit, to characterize the nature of the atmosphere, and to predict the atmosphere for future orbits. To interpret the accelerometer data, a data reduction procedure was developed to produce density estimations utilizing inputs from the spacecraft, the Navigation Team, and pre-mission aerothermodynamic studies. This data reduction procedure was based on the calculation of aerodynamic forces from the accelerometer data by considering acceleration due to gravity gradient, solar pressure, angular motion of the MGS, instrument bias, thruster activity, and a vibration component due to the motion of the damaged solar array. Methods were developed to calculate all of the acceleration components including a 4 degree of freedom dynamics model used to gain a greater understanding of the damaged solar array. The total error inherent to the data reduction procedure was calculated as a function of altitude and density considering contributions from ephemeris errors, errors in force coefficient, and instrument errors due to bias and digitization. Comparing the results from this procedure to the data of other MGS Teams has demonstrated that this procedure can quickly and accurately describe the density and vertical structure of the Martian upper atmosphere.

  1. Water and Water Ions in the Martian Thermosphere/Ionosphere

    Science.gov (United States)

    Fox, J. L.; Benna, M.; Mahaffy, P. R.; Jakosky, B. M.

    2015-12-01

    We present here the first model of the Martian thermosphere/ionosphere in which we predict the density profiles of water vapor and water ions in the altitude range 80 to 400 km. The model is based on data from the MAVEN spacecraft, including the NGIMS, LPW, EUVM and STATIC. The model includes 28 ions, of which 14 are protonated species, and 10 minor neutral species. The protonated species include H2O+ and H3O+, and the minor neutral species include H2O. These species are coupled to each other and to the background species by over 400 reactions. The peaks of the density profiles of water ions and OH+ are in fairly good agreement with the values measured by the NGIMS instrument. The density profiles of water vapor are computed with zero flux boundary conditions at the top and bottom of the model, which shows that water can be made in situ via ion chemistry, somewhat like in the interstelllar medium. It appears, however, that the predicted densities may be too small to account for the densities of H3O+ that are seen at low altitudes beyond the terminator. On the other hand, the densities of water vapor must be small enough so that HCO+ is not destroyed completely by proton transfer. The actual amount of water in the thermosphere is bracketed by these two requirements. The computed water vapor densities at the lower boundary are smaller than some of those at the upper boundaries of middle atmosphere models. We tentatively predict that there must be some influx of water from below. We also compute the Hn + species, where n=(1-3), and convincingly demonstrate the the mass-2 ion is H2+ and not D+, as it is on Venus.

  2. Thermospheric density estimation and responses to the March 2013 geomagnetic storm from GRACE GPS-determined precise orbits

    Science.gov (United States)

    Calabia, Andres; Jin, Shuanggen

    2017-02-01

    The thermospheric mass density variations and the thermosphere-ionosphere coupling during geomagnetic storms are not clear due to lack of observables and large uncertainty in the models. Although accelerometers on-board Low-Orbit-Earth (LEO) satellites can measure non-gravitational accelerations and derive thermospheric mass density variations with unprecedented details, their measurements are not always available (e.g., for the March 2013 geomagnetic storm). In order to cover accelerometer data gaps of Gravity Recovery and Climate Experiment (GRACE), we estimate thermospheric mass densities from numerical derivation of GRACE determined precise orbit ephemeris (POE) for the period 2011-2016. Our results show good correlation with accelerometer-based mass densities, and a better estimation than the NRLMSISE00 empirical model. Furthermore, we statistically analyze the differences to accelerometer-based densities, and study the March 2013 geomagnetic storm response. The thermospheric density enhancements at the polar regions on 17 March 2013 are clearly represented by POE-based measurements. Although our results show density variations better correlate with Dst and k-derived geomagnetic indices, the auroral electroject activity index AE as well as the merging electric field Em picture better agreement at high latitude for the March 2013 geomagnetic storm. On the other side, low-latitude variations are better represented with the Dst index. With the increasing resolution and accuracy of Precise Orbit Determination (POD) products and LEO satellites, the straightforward technique of determining non-gravitational accelerations and thermospheric mass densities through numerical differentiation of POE promises potentially good applications for the upper atmosphere research community.

  3. Observations and simulations of midlatitude ionospheric and thermospheric response to the January 2013 stratospheric sudden warming event

    Science.gov (United States)

    Wu, Qian; Maute, A.; Yudin, V.; Goncharenko, L.; Noto, J.; Kerr, R.; Jacobi, Christoph

    2016-09-01

    Using observations from midlatitudes, we examine the ionospheric and thermospheric responses to the 2013 stratospheric sudden warming event by comparing data with four simulations performed by the Whole Atmosphere Community Climate Model eXtended (WACCM-X), Thermosphere-Ionosphere Mesosphere Electrodynamics General Circulation Model (TIMEGCM), and Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIEGCM). The WACCM-X simulation was nudged by the GEOS-5 data. The two TIMEGCM simulations were nudged by the Modern-Era Retrospective analysis for Research and Applications data and by the aforementioned WACCM-X outputs, respectively. The standard TIEGCM simulation was also performed. These four simulations were compared with Millstone Hill (42.6°N, 71.4°W) incoherent scatter radar data, Millstone Hill and Boulder (40.1°N, 105.2°W) upper and lower thermospheric wind data. The meteor radar data from Collm (51.3°N, 13°E) were also used to examine the zonal wave number of the semidiurnal tide (SD). We evaluate the model simulations of the mesospheric and thermospheric responses to the 2013 SSW. The TIMEGCM simulation nudged with the WACCM-X output has suitable stratospheric input and ionospheric dynamics and can reproduce a sharp rise of hmf2 on January 12 observed by the Millstone Hill radar. The comparison of different models with the lower thermospheric SD tide yielded mixed results. The SD tide maintained mostly as a migrating tide for most of the time and matched the TIEGCM simulation very well. The WACCM-X appeared to perform better when the observed SD tide displays the large phase shift. It also has larger and more variable SD tide amplitude. The two TIMEGCM simulations have smaller SD amplitudes in general. Observations showed complex SD tide patterns after 20 January, which was difficult to characterize as a migrating tidal mode.

  4. Thermospheric Nitric Oxide Response to Shock-led Storms.

    Science.gov (United States)

    Knipp, D J; Pette, D V; Kilcommons, L M; Isaacs, T L; Cruz, A A; Mlynczak, M G; Hunt, L A; Lin, C Y

    2017-02-01

    We present a multi-year superposed epoch study of the Sounding of the Atmosphere using Broadband Emission Radiometry nitric oxide (NO) emission data. NO is a trace constituent in the thermosphere that acts as cooling agent via infrared (IR) emissions. The NO cooling competes with storm time thermospheric heating resulting in a thermostat effect. Our study of nearly 200 events reveals that shock-led interplanetary coronal mass ejections (ICMEs) are prone to early and excessive thermospheric NO production and IR emissions. Excess NO emissions can arrest thermospheric expansion by cooling the thermosphere during intense storms. The strongest events curtail the interval of neutral density increase and produce a phenomenon known as thermospheric 'overcooling'. We use Defense Meteorological Satellite Program particle precipitation data to show that interplanetary shocks and their ICME drivers can more than double the fluxes of precipitating particles that are known to trigger the production of thermospheric NO. Coincident increases in Joule heating likely amplify the effect. In turn, NO emissions more than double. We discuss the roles and features of shock/sheath structures that allow the thermosphere to temper the effects of extreme storm time energy input and explore the implication these structures may have on mesospheric NO. Shock-driven thermospheric NO IR cooling likely plays an important role in satellite drag forecasting challenges during extreme events.

  5. Application of Accelerometer Data to Mars Odyssey Aerobraking and Atmospheric Modeling

    Science.gov (United States)

    Tolson, R. H.; Keating, G. M.; George, B. E.; Escalera, P. E.; Werner, M. R.; Dwyer, A. M.; Hanna, J. L.

    2002-01-01

    Aerobraking was an enabling technology for the Mars Odyssey mission even though it involved risk due primarily to the variability of the Mars upper atmosphere. Consequently, numerous analyses based on various data types were performed during operations to reduce these risk and among these data were measurements from spacecraft accelerometers. This paper reports on the use of accelerometer data for determining atmospheric density during Odyssey aerobraking operations. Acceleration was measured along three orthogonal axes, although only data from the component along the axis nominally into the flow was used during operations. For a one second count time, the RMS noise level varied from 0.07 to 0.5 mm/s2 permitting density recovery to between 0.15 and 1.1 kg per cu km or about 2% of the mean density at periapsis during aerobraking. Accelerometer data were analyzed in near real time to provide estimates of density at periapsis, maximum density, density scale height, latitudinal gradient, longitudinal wave variations and location of the polar vortex. Summaries are given of the aerobraking phase of the mission, the accelerometer data analysis methods and operational procedures, some applications to determining thermospheric properties, and some remaining issues on interpretation of the data. Pre-flight estimates of natural variability based on Mars Global Surveyor accelerometer measurements proved reliable in the mid-latitudes, but overestimated the variability inside the polar vortex.

  6. INSIGHT (interaction of low-orbiting satellites with the surrounding ionosphere and thermosphere)

    Science.gov (United States)

    Schlicht, Anja; Reussner, Elisabeth; Lühr, Hermann; Stolle, Claudia; Xiong, Chao; Schmidt, Michael; Blossfeld, Mathis; Erdogan, Eren; Pancetta, Francesca; Flury, Jakob

    2016-04-01

    In the framework of the DFG special program "Dynamic Earth" the project INSIGHT, started in September 2015, is studying the interactions between the ionosphere and thermosphere as well as the role of the satellites and their instruments in observing the space environment. Accelerometers on low-Earth orbiters (LEOs) are flown to separate non-gravitational forces acting on the satellite from influences of gravitational effects. Amongst others these instruments provide valuable information for improving our understanding of thermospheric properties like densities and winds. An unexpected result, for example, is the clear evidence of geomagnetic field control on the neutral upper atmosphere. The charged particles of the ionosphere act as mediators between the magnetic field and the thermosphere. In the framework of INSIGHT the climatology of the thermosphere will be established and the coupling between the ionosphere and thermosphere is studied. There are indications that the accelerometers are influenced by systematic errors not identified up to now. For GRACE it is one of the discussed reasons, why this mission so far did not reach the baseline accuracy. Beutler et al. 2010 discussed the limited use of the GRACE accelerometer measurements in comparison to stochastic pulses in gravity field recovery. Analysis of the accelerometer measurements show many structures in the high frequency region which can be traced back to switching processes of electric circuits in the spacecraft, like heater and magnetic torquer switching, or so called twangs, which can be associated with discharging of non-conducting surfaces of the satellite. As all observed signals have the same time dependency a common origin is very likely, namely the coupling of time variable electric currents into the accelerometer signal. In GOCE gravity field gradients non-gravitational signatures around the magnetic poles are found indicating that even at lower frequencies problems occur. INSIGHT will identify

  7. General circulation modeling of the thermosphere-ionosphere during a geomagnetic storm

    Science.gov (United States)

    Yiǧit, Erdal; Immel, Thomas; Ridley, Aaron; Frey, Harald U.; Moldwin, Mark

    2016-07-01

    Using a three-dimensional general circulation model (GCM) of the upper atmosphere, we investigate the response of the thermosphere-ionosphere system to the August 2011 major geomagnetic storm. The GCM is driven by measured storm-time input data of the Interplanetary Magnetic Field (IMF), solar activity, and auroral activity. Simulations for quiet steady conditions over the same period are performed as well in order to assess the response of the neutral and plasma parameters to the storm. During the storm, the high-latitude mean ion flows are enhanced by up to ~150%. Overall, the global mean neutral temperature increases by up to 15%, while the maximum thermal response is higher in the winter Southern Hemisphere at high-latitudes than the summer Northern Hemisphere: 40% vs. 20% increase in high-latitude mean temperature, respectively. The global mean Joule heating of the neutral atmosphere increases by more than a factor of three. There are distinct hemispheric differences in the magnitude and morphology of the horizontal ion flows and thermospheric circulation during the different phases of the storm. The thermospheric circulation demonstrates the largest amount of hemispheric differences during the later stages of the storm. Dynamical diagnostics show that advective forcing contributes to hemispheric differences.

  8. Ionosphere-Thermosphere Coupling and Energy Partitioning During Two HSS Events

    Science.gov (United States)

    Verkhoglyadova, Olga; Mannucci, Anthony; Meng, Xing; Tsurutani, Bruce; Mlynczak, Martin; Hunt, Linda; Redmon, Robert; Green, Janet

    2015-04-01

    We analyze external driving of the ionosphere-thermosphere (IT) system during two CIR-HSS events, on 29 April - 4 May 2011 and on 8-12 May 2012. By studying similar CIR-HSS events in the same phase of a solar cycle and the same season we aim to understand differences and similarities in the magnetosphere-IT coupling caused by external driving and other factors (pre-conditioning or driving from below). We focus on understanding energy and momentum transfer (with solar wind coupling functions, Joule heating, nitric oxide (NO) infrared cooling radiation and energetic particle precipitation) and corresponding energy partitioning in the IT system. We utilize observations from DMSP, POES/MEPED and TIMED/SABER. We use the Global Ionosphere-Thermosphere Model (GITM, Ridley et al., 2006) with different driving inputs to understand the IT response. We outline a physics-based approach for forecasting moderate to intense storms in the Earth's upper atmosphere caused by solar wind disturbances. Ridley, A. J., Y. Deng, and G. Toth (2006), The global ionosphere-thermosphere model, Journal of Atmospheric and Solar-Terrestrial Physics, 68(8), 839-864, doi:10.1016/j.jastp.2006.01.008.

  9. New modes and mechanisms of thermospheric mass density variations from GRACE accelerometers

    Science.gov (United States)

    Calabia, Andres; Jin, Shuanggen

    2016-11-01

    Monitoring and understanding the upper atmosphere processes is important for orbital decay and space physics. Nowadays, Low Earth Orbit (LEO) accelerometers provide a unique opportunity to study thermospheric density variations with unprecedented details. In this paper, thermospheric mass densities variations from Gravity Recovery and Climate Experiment (GRACE) accelerometers are investigated for the period 2003-2016 using the principal component analysis (PCA). The resulting modes are analyzed and parameterized in terms of solar and magnetospheric forcing, local solar time (LST), and annual variations. A better understanding of global thermospheric air density variations is presented, which validates the suitability of our technique and model. The parameterization of the subsolar-point annual variation shows two maxima around June and only one in December. The LST parameterization shows a new fluctuation controlling a middle latitude four-wave pattern, with two maxima at 12 h and 21 h LST and two minima at 1 h and 17 h LST. Our parameterizations are suitable to represent small-scale variations including, e.g., the equatorial mass density anomaly (EMA) and the midnight density maximum (MDM). Finally, the residuals are analyzed in the spectral domain, and additional contributions are found at the frequencies of the radiational tides and at the periods of 83, 93, 152, and 431 days.

  10. Improved short-term variability in the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model

    Science.gov (United States)

    Häusler, K.; Hagan, M. E.; Baumgaertner, A. J. G.; Maute, A.; Lu, G.; Doornbos, E.; Bruinsma, S.; Forbes, J. M.; Gasperini, F.

    2014-08-01

    We report on a new source of tidal variability in the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). Lower boundary forcing of the TIME-GCM for a simulation of November-December 2009 based on 3-hourly Modern-Era Retrospective Analysis for Research and Application (MERRA) reanalysis data includes day-to-day variations in both diurnal and semidiurnal tides of tropospheric origin. Comparison with TIME-GCM results from a heretofore standard simulation that includes climatological tropospheric tides from the global-scale wave model reveal evidence of the impacts of MERRA forcing throughout the model domain, including measurable tidal variability in the TIME-GCM upper thermosphere. Additional comparisons with measurements made by the Gravity field and steady-state Ocean Circulation Explorer satellite show improved TIME-GCM capability to capture day-to-day variations in thermospheric density for the November-December 2009 period with the new MERRA lower boundary forcing.

  11. Mars dayside temperature from airglow limb profiles : comparison with in situ measurements and models

    Science.gov (United States)

    Gérard, Jean-Claude; Bougher, Stephen; Montmessin, Franck; Bertaux, Jean-Loup; Stiepen, A.

    The thermal structure of the Mars upper atmosphere is the result of the thermal balance between heating by EUV solar radiation, infrared heating and cooling, conduction and dynamic influences such as gravity waves, planetary waves, and tides. It has been derived from observations performed from different spacecraft. These include in situ measurements of orbital drag whose strength depends on the local gas density. Atmospheric temperatures were determined from the altitude variation of the density measured in situ by the Viking landers and orbital drag measurements. Another method is based on remote sensing measurements of ultraviolet airglow limb profiles obtained over 40 years ago with spectrometers during the Mariner 6 and 7 flybys and from the Mariner 9 orbiter. Comparisons with model calculations indicate that they both reflect the CO_2 scale height from which atmospheric temperatures have been deduced. Upper atmospheric temperatures varying over the wide range 270-445 K, with a mean value of 325 K were deduced from the topside scale height of the airglow vertical profile. We present an analysis of limb profiles of the CO Cameron (a(3) Pi-X(1) Sigma(+) ) and CO_2(+) doublet (B(2) Sigma_u(+) - X(2) PiΠ_g) airglows observed with the SPICAM instrument on board Mars Express. We show that the temperature in the Mars thermosphere is very variable with a mean value of 270 K, but values ranging between 150 and 400 K have been observed. These values are compared to earlier determinations and model predictions. No clear dependence on solar zenith angle, latitude or season is apparent. Similarly, exospheric variations with F10.7 in the SPICAM airglow dataset are small over the solar minimum to moderate conditions sampled by Mars Express since 2005. We conclude that an unidentified process is the cause of the large observed temperature variability, which dominates the other sources of temperature variations.

  12. Circulation in the high-latitude thermosphere due to electric fields and Joule heating

    Science.gov (United States)

    Heaps, M. G.; Megill, L. R.

    1975-01-01

    Electric fields in the earth's upper atmosphere are capable of setting the neutral atmosphere in motion via ion-neutral collisions as well as pressure gradients from resultant Joule heating. By means of simple models for the high-latitude thermosphere and electric fields a simplified set of coupled equations is solved which show that moderate electric fields, when present for a period of several hours, are capable of displacing the neutral atmosphere of the order of 50 km in the vertical, a few hundred kilometers in the north-south direction and over 1000 km in the east-west direction.

  13. Semi-Empirical, First-Principles, and Hybrid Modeling of the Thermosphere to Enhance Data Assimilation

    Science.gov (United States)

    2015-10-27

    Mauersberger, K., D. C. Kayser, W. E. Potter , and A. O. Nier (1976), Seasonal variation of neutral thermospheric constituents in the Northern Hemisphere...J. Geophys. Res., 81, pp. 7–11, doi:10.1029/JA081i001p00007. [41] Mauersberger, K., W. E. Potter , and D. C. Kayser (1976), A direct measurement of...Geophys. Res., 79, p. 619, doi:10.1029/JA079i004p00619. [45] Mayr, H. G., I. Harris , and N. W. Spencer (1978), Some properties of upper atmosphere

  14. Numerical modelling of the thermospheric and ionospheric effects of magnetospheric processes in the cusp region

    Directory of Open Access Journals (Sweden)

    A. A. Namgaladze

    Full Text Available The thermospheric and ionospheric effects of the precipitating electron flux and field-aligned-current variations in the cusp have been modelled by the use of a new version of the global numerical model of the Earth's upper atmosphere developed for studies of polar phenomena. The responses of the electron concentration, ion, electron and neutral temperature, thermospheric wind velocity and electric-field potential to the variations of the precipitating 0.23-keV electron flux intensity and field-aligned current density in the cusp have been calculated by solving the corresponding continuity, momentum and heat balance equations. Features of the atmospheric gravity wave generation and propagation from the cusp region after the electron precipitation and field-aligned current-density increases have been found for the cases of the motionless and moving cusp region. The magnitudes of the disturbances are noticeably larger in the case of the moving region of the precipitation. The thermospheric disturbances are generated mainly by the thermospheric heating due to the soft electron precipitation and propagate to lower latitudes as large-scale atmospheric gravity waves with the mean horizontal velocity of about 690 m s–1. They reveal appreciable magnitudes at significant distances from the cusp region. The meridional-wind-velocity disturbance at 65° geomagnetic latitude is of the same order (100 m s–1 as the background wind due to the solar heating, but is oppositely directed. The ionospheric disturbances have appreciable magnitudes at the geomagnetic latitudes 70°–85°. The electron-concentration and -temperature disturbances are caused mainly by the ionization and heating processes due to the precipitation, whereas the ion-temperature disturbances are influence strongly by Joule heating of the ion gas due to the electric-field disturbances in the cusp. The latter strongly influence the

  15. Evidence of long term global decline in the Earth's thermospheric densities apparently related to anthropogenic effects

    Science.gov (United States)

    Keating, G. M.; Tolson, R. H.; Bradford, M. S.

    2000-05-01

    A study was performed of the long-term orbital decay of five Earth satellites with perigee altitudes averaging near 350km. To decouple long-term trend measurements from the effects of solar variability, measurements were evaluated during the years of solar minimum (1976, 1986 and 1996). Atmospheric densities derived from these essentially global measurements showed substantial evidence of a decline averaging 9.8 ± 2.5% in thermospheric density over 20 years pointing toward a long-term cooling of the upper atmosphere. Increases in greenhouse gases induced by human activity are hypothesized to warm the Earth's surface and lower atmosphere, but strongly cool the upper atmosphere. Assuming that the 10% increase in CO2 over these 20 years caused cooling resulting in the 10% decline in density, a doubling of CO2 could cause the thermospheric densities measured near 350km to decrease by a factor of 3. This decrease may shrink the altitude of a constant density surface by 40km before the end of the 21st century.

  16. Achievements in atmospheric science from Spacelab: The mesosphere/lower thermosphere

    Science.gov (United States)

    Torr, D. G.

    1994-01-01

    The Mesosphere and Lower Thermosphere (MLT) are adjacent regions of the upper atmosphere that cannot be easily accessed (except by rockets) by in situ measurement. For this reason, the MLT l essentially represents the last unexplored region of the planet. The advent of the shuttle and remote sensing technology over the last decade and a half have changed this situation significantly. Spacelab 1 carried the first payload of instruments capable of acquiring a comprehensive database on the MLT region, and much was learned on that mission that was subsequently used to have greatly improve the measurement capability. The ATLAS 1 payload was probably the most comprehensive ever launched to study upper atmosphere, and the mission was reported as being one of the most successful of NASA's endeavor's to date. The database acquired on ATLAS 1 will provide a reference that will be used for many years to come. It will also provide the means to gaining the first quantitative understanding of the photochemistry of the lower thermosphere and mesosphere.

  17. ADAPTIVE MODEL REFINEMENT FOR THE IONOSPHERE AND THERMOSPHERE

    Data.gov (United States)

    National Aeronautics and Space Administration — ADAPTIVE MODEL REFINEMENT FOR THE IONOSPHERE AND THERMOSPHERE ANTHONY M. D’AMATO∗, AARON J. RIDLEY∗∗, AND DENNIS S. BERNSTEIN∗∗∗ Abstract. Mathematical models of...

  18. Parameterization of Nitric Oxide Emissions in the Thermosphere

    Science.gov (United States)

    Lin, C. Y. T.; Deng, Y.; Venkataramani, K.; Yonker, J. D.; Bailey, S. M.

    2016-12-01

    Nitric oxide (NO), a minor species in the thermosphere, is an important indicator of energy balance. It also has the lowest ionization threshold so is the terminal ion in the ionospheric E-region. Discrepancies between observations and modeled results challenge current understanding of ionospheric and thermospheric energy budget especially during geophysical events. Work in the recent decades has significantly improved our understanding of the NO chemistry and in particular its relationship to energy inputs, such as the role of the excited state of nitrogen, N2(A), in the NO reactions. We update the NO chemical reactions and introduce N2(A) in the Global Ionosphere Thermosphere Model (GITM) to study NO density and cooling in the lower thermosphere. The results are compared with the TIMED SABER and GUVI measurements to identify the relative contribution from solar irradiance and geomagnetic activity to 5.3 µm emission by NO. A parameterization scheme is proposed to be used in a global circulation model.

  19. An exospheric temperature model from CHAMP thermospheric density

    Science.gov (United States)

    Weng, Libin; Lei, Jiuhou; Sutton, Eric; Dou, Xiankang; Fang, Hanxian

    2017-02-01

    In this study, the effective exospheric temperature, named as T∞, derived from thermospheric densities measured by the CHAMP satellite during 2002-2010 was utilized to develop an exospheric temperature model (ETM) with the aid of the NRLMSISE-00 model. In the ETM, the temperature variations are characterized as a function of latitude, local time, season, and solar and geomagnetic activities. The ETM is validated by the independent GRACE measurements, and it is found that T∞ and thermospheric densities from the ETM are in better agreement with the GRACE data than those from the NRLMSISE-00 model. In addition, the ETM captures well the thermospheric equatorial anomaly feature, seasonal variation, and the hemispheric asymmetry in the thermosphere.

  20. An aeronomy mission to investigate the entry and orbiter environment of Mars

    Science.gov (United States)

    Brace, Larry H.

    1989-01-01

    The need for an aeronomy mission to Mars as a precursor to a manned Mars mission is discussed. The upper atmosphere and radiation environment of Mars are reviewed, focusing on the implications of the Martian atmosphere for a manned mission. Plans for an aeronomy mission to Mars are described, including the Mars Aeronomy Observer and the Earth/Mars Aeronomy Orbiter.

  1. Ionosphere-Thermosphere Coupling - Data Analysis and Numerical Simulation Study

    Science.gov (United States)

    2013-12-12

    Circulation Model (TIE- GCM) is a first-principles, three-dimensional, non -linear representation of the coupled thermosphere and ionosphere system. It...method for given distributions of precipitating energy fluxes. Note that the parameterization of Roble and Ridley [1987] was designed for a Maxwellian ...results from the non -hydrostatic GCM, GITM and Fang’s parameterization models. 3.3 GITM The Global Ionosphere-Thermosphere Model (GITM) is a three

  2. Mean thermospheric winds observed from Halley, Antarctica

    Directory of Open Access Journals (Sweden)

    R. I. Crickmore

    Full Text Available Thermospheric winds on a total of 237 nights have been studied for the effects due to geomagnetic activity, solar flux, and season. The observations have been made from 1988 to 1992 by a Fabry-Perot interferometer (FPI operating at Halley (75.5°S, 26.6°W, Antarctica. This is the first statistical study of thermospheric winds near the southern auroral zone. The main factor affecting the wind velocities is the geomagnetic activity. Increases in activity cause an increase in the maximum equatorward wind, and cause the zonal wind in the evening to become more westward. Smaller changes in the mean wind occur with variations in season and solar flux. The small variation with solar flux is more akin to the situation found at mid-latitudes than at high latitudes. Since the geomagnetic latitude of Halley is only 61°, it suggests that the variability of the wind with solar flux may depend more on geomagnetic than geographic latitude. These observations are in good agreement with the empirical Horizontal Wind Model (HWM90. However, comparisons with predictions of the Vector Spherical Harmonic Model (VSH show that for low geomagnetic activity the predicted phases of the two components of the wind closely resemble the observations but the modelled amplitudes are too small by a factor of two. At high geomagnetic activity the major differences are that modelled zonal velocity is too westward in the evening and too eastward after 04 UT. The modelled ion densities at the F-region peak are a factor of up to 9 too large, whilst the predicted mean value and diurnal variation of the altitude of the peak are significantly lower than those observed. It is suggested that these differences result from the ion loss rate being too low, and an inaccurate model of the magnetic field.

  3. Ionospheric and Thermospheric Imaging from Geosynchronous Orbit

    Science.gov (United States)

    McCoy, R. P.; Wood, K.; Dymond, K. F.; Thonnard, S. E.; Cannon, K.; Makela, J.

    2001-12-01

    The Office of Naval Research is sponsoring the development of an ultraviolet imaging system to test the concept of real-time synoptic observations of the ionosphere and thermosphere from geosynchronous orbit. The observational hardware consists of two ultraviolet telescopes mounted to a two-axis gimbal to measure airglow radiances on the disk and limb of the Earth. A far-ultraviolet telescope will use a filter wheel with filters to image atomic oxygen emission at 130.4 nm, 135.6 nm, and molecular nitrogen emission at 143.0 nm. An extreme-ultraviolet telescope will image the oxygen ion airglow at 83.4 nm. The oxygen emission measurements will be used to infer nightside ionospheric total electron content (TEC) on the disk and electron density profiles on the limb. On the dayside the oxygen ion measurements will be used to determine electron density profiles, and the oxygen and nitrogen measurements will be used to infer thermospheric neutral density profiles on the limb and O/N2 ratios on the disk. The telescope fields of view cover a 1000 km x 1000 km region with 10 km x 10 km resolution. A goal for nightside TEC measurements is to obtain images with 100 second integrations and to be able to track ionospheric irregularities in real time as "weather systems". Ratios of oxygen nightglow measurements will be used to explore the possibility of providing three dimensional measurements of the ionosphere. These telescopes will be mounted aboard an Air Force Space Test Program satellite which will be launched into geosynchronous orbit over the continental U. S. for about year and then moved over the Indian Ocean for an additional seven years.

  4. Effects of planetary-scale waves on temporal wind variations in the Venusian thermosphere

    Science.gov (United States)

    Hoshino, N.; Fujiwara, H.; Takagi, M.; Takahashi, Y.; Kasaba, Y.

    2008-12-01

    In recent years, the importance of planetary-scale waves for dynamics of the Venusian upper atmosphere has been recognized. For example, Forbes and Knopliv [2007] suggested propagations of planetary-scale waves originated in the cloud deck to the thermosphere from reanalysis of the Magellan spacecraft data. In addition, recent simulation studies suggest importance of tidal waves for the superrotation in the Venusian cloud deck [Takagi and Matsuda, 2007]. Venus Climate Orbiter (VCO), which will be launched in 2010 as the second Japanese planetary mission, is expected to provide precious information about upward propagating planetary scale-waves which can't be obtained by Venus Express because of the polar orbit and the close-up observations. In order to understand effects of the planetary-scale waves propagating from the cloud top on the thermospheric circulation, we have developed a new general circulation model (GCM) which includes about 80-200 km altitude region. The GCM solves the primitive equations for momentum, energy and composition. The solar EUV heating, NIR heating and 15μm Radiative cooling are considered. We also consider O, CO and CO2 as the major composition of the Venusian mesosphere and thermosphere. The horizontal and vertical resolutions are 10° in longitude, 20° in latitude, and 0.5 scale height in altitude, respectively. In this study, we perform GCM simulations with use of global distributions of planetary-scale waves taking into account the recent simulation results [e.g., Takagi and Matsuda, 2007] and the past observations [e.g., Del genio and Rossow, 1990]. We will also develop a method for GCM simulations with the VCO data.

  5. Energy Budget of the Thermosphere and Mesosphere from 15 Years of SABER Observations

    Science.gov (United States)

    Hunt, L. A.; Mlynczak, M. G.; Marshall, B. T.; Russell, J. M., III

    2016-12-01

    The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite has provided nearly 15 years of continuous measurements in the mesosphere and thermosphere and operations are ongoing. The SABER instrument has performed exceptionally well since its launch in December 2001, and several more years of observations are eagerly anticipated. SABER is a limb-scanning instrument that makes vertical profile measurements of infrared radiance in ten channels chosen to permit retrieval or derivation of a variety of data products. These include radiative emission of NO at 5.3 μm and CO2 at 15 μm, two key components that govern radiative cooling of the atmosphere above 100 km. Other channels provide information about the thermal structure and elements of the energy budget of the upper mesosphere. From SABER radiances, we determine amounts of atomic oxygen and hydrogen, radiative cooling by CO2, solar heating by O3 and O2, and chemical heating from a suite of exothermic reactions over the vertical range of 65-100 km. We have observed changes in the energy budgets of these regions from mid-solar cycle 23 to the current downturn in solar cycle 24, encompassing portions of two very different solar cycles and the unusually long solar minimum between them. This talk focuses on the natural variability in the composition and energy budget of the mesosphere and lower thermosphere imposed by the variability of the Sun over the past 15 years.

  6. High-altitude gravity waves in the Martian thermosphere observed by MAVEN/NGIMS and modeled by a gravity wave scheme

    CERN Document Server

    Yiğit, Erdal; Liu, Guiping; Medvedev, Alexander S; Mahaffy, Paul R; Kuroda, Takeshi; Jakosky, Bruce M

    2015-01-01

    First high-altitude observations of gravity wave (GW)-induced CO$_2$ density perturbations in the Martian thermosphere retrieved from NASA's NGIMS instrument on board the MAVEN satellite are presented and interpreted using the extended GW parameterization of Yi\\u{g}it et al. [2008] and the Mars Climate Database as an input. Observed relative density perturbations between 180-220 km of 20-40 % demonstrate appreciable local time, latitude, and altitude variations. Modeling for the spatiotemporal conditions of the MAVEN observations suggests that GWs can directly propagate from the lower atmosphere to the thermosphere, produce appreciable dynamical effects, and likely contribute to the observed fluctuations. Modeled effects are somewhat smaller than the observed but their highly variable nature is in qualitative agreement with observations. Possible reasons for discrepancies between modeling and measurements are discussed.

  7. Global change induced trends in ion composition of the troposphere to the lower thermosphere

    Directory of Open Access Journals (Sweden)

    G. Beig

    2008-05-01

    Full Text Available In this paper a brief overview of the changes in atmospheric ion compositions driven by the human-induced changes in related neutral species, and temperature from the troposphere to lower thermosphere has been made. It is found that ionic compositions undergo significant variations. The variations calculated for the double-CO2 scenario are both long-term and permanent in nature. Major neutrals which take part in the lower and middle atmospheric ion chemical schemes and undergo significant changes due to anthropogenic activities are: O, O2, H2O, NO, acetonitrile, pyridinated compounds, acetone and aerosol. The concentration of positive ion/electron density does not change appreciably in the middle atmosphere but indicates a marginal decrease above about 75 km until about 85 km, above which the magnitude of negative trend decreases and becomes negligible at 93 km. Acetonitrile cluster ions in the upper stratosphere are likely to increase, whereas NO+ and NO+(H2O in the mesosphere and lower thermosphere (MLT region are expected to decrease for the double CO2 scenario. It is also found that the atmospheric density of pyridinated cluster ions is fast rising in the troposphere.

  8. Alfvén waves as a solar-interplanetary driver of the thermospheric disturbances.

    Science.gov (United States)

    Guo, Jianpeng; Wei, Fengsi; Feng, Xueshang; Liu, Huixin; Wan, Weixing; Yang, Zhiliang; Xu, Jiyao; Liu, Chaoxu

    2016-01-01

    Alfvén waves have been proposed as an important mechanism for the heating of the Sun's outer atmosphere and the acceleration of solar wind, but they are generally believed to have no significant impact on the Earth's upper atmosphere under quiet geomagnetic conditions due to their highly fluctuating nature of interplanetary magnetic field (i.e., intermittent southward magnetic field component). Here we report that a long-duration outward propagating Alfvén wave train carried by a high-speed stream produced continuous (~2 days) and strong (up to ± 40%) density disturbances in the Earth's thermosphere in a way by exciting multiple large-scale gravity waves in auroral regions. The observed ability of Alfvén waves to excite large-scale gravity waves, together with their proved ubiquity in the solar atmosphere and solar wind, suggests that Alfvén waves could be an important solar-interplanetary driver of the global thermospheric disturbances.

  9. Improved forecasting of thermospheric densities using multi-model ensembles

    Science.gov (United States)

    Elvidge, Sean; Godinez, Humberto C.; Angling, Matthew J.

    2016-07-01

    This paper presents the first known application of multi-model ensembles to the forecasting of the thermosphere. A multi-model ensemble (MME) is a method for combining different, independent models. The main advantage of using an MME is to reduce the effect of model errors and bias, since it is expected that the model errors will, at least partly, cancel. The MME, with its reduced uncertainties, can then be used as the initial conditions in a physics-based thermosphere model for forecasting. This should increase the forecast skill since a reduction in the errors of the initial conditions of a model generally increases model skill. In this paper the Thermosphere-Ionosphere Electrodynamic General Circulation Model (TIE-GCM), the US Naval Research Laboratory Mass Spectrometer and Incoherent Scatter radar Exosphere 2000 (NRLMSISE-00), and Global Ionosphere-Thermosphere Model (GITM) have been used to construct the MME. As well as comparisons between the MMEs and the "standard" runs of the model, the MME densities have been propagated forward in time using the TIE-GCM. It is shown that thermospheric forecasts of up to 6 h, using the MME, have a reduction in the root mean square error of greater than 60 %. The paper also highlights differences in model performance between times of solar minimum and maximum.

  10. Acoustic Resonance between Ground and Thermosphere

    Directory of Open Access Journals (Sweden)

    M Matsumura

    2009-04-01

    Full Text Available Ultra-low frequency acoustic waves called "acoustic gravity waves" or "infrasounds" are theoretically expected to resonate between the ground and the thermosphere. This resonance is a very important phenomenon causing the coupling of the solid Earth, neutral atmosphere, and ionospheric plasma. This acoustic resonance, however, has not been confirmed by direct observations. In this study, atmospheric perturbations on the ground and ionospheric disturbances were observed and compared with each other to confirm the existence of resonance. Atmospheric perturbations were observed with a barometer, and ionospheric disturbances were observed using the HF Doppler method. An end point of resonance is in the ionosphere, where conductivity is high and the dynamo effect occurs. Thus, geomagnetic observation is also useful, so the geomagnetic data were compared with other data. Power spectral density was calculated and averaged for each month. Peaks appeared at the theoretically expected resonance frequencies in the pressure and HF Doppler data. The frequencies of the peaks varied with the seasons. This is probably because the vertical temperature profile of the atmosphere varies with the seasons, as does the reflection height of infrasounds. These results indicate that acoustic resonance occurs frequently.

  11. Effects of 27-day averaged tidal forcing on the thermosphere-ionosphere as examined by the TIEGCM

    Science.gov (United States)

    Maute, A. I.; Forbes, J. M.; Hagan, M. E.

    2016-12-01

    The variability of the ionosphere and thermosphere is influenced by solar and geomagnetic forcing and by lower atmosphere coupling. During the last solar minimum low- and mid-latitude ionospheric observations have shown strong longitudinal signals which are associated with upward propagating tides. Progress has been made in explaining observed ionospheric and thermospheric variations by investigating possible coupling mechanisms e.g., wind dynamo, propagation of tides into the upper thermosphere, global circulation changes, and compositional effects. To fully understand the vertical coupling a comprehensive set of simultaneous measurements of key quantities is missing. The Ionospheric Connection (ICON) explorer will provide such a data set and the data interpretation will be supported by numerical modeling to investigate the lower to upper atmosphere coupling. Due to ICON's orbit, 27 days of measurements are needed to cover all longitudes and local times and to be able to derive tidal components. In this presentation we employ the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) to evaluate the influence of the 27-day processing window on the ionosphere and thermosphere state. Specifically, we compare TIEGCM simulations that are forced at its 97 km lower boundary by daily tidal fields from 2009 MERRA-forced TIME-GCM output [Häusler et al., 2015], and by the corresponding 27-day mean tidal fields. Apart from the expected reduced day-to-day variability when using 27-day averaged tidal forcing, the simulations indicate net NmF2 changes at low latitudes, which vary with season. First results indicate that compositional effects may influence the Nmf2 modifications. We will quantify the effect of using a 27-day averaged diurnal tidal forcing versus daily ones on the equatorial vertical drift, low and mid-latitude NmF2 and hmF2, global circulation, and composition. The possible causes for the simulated changes will be examined. The result of

  12. Where does the Thermospheric Ionospheric GEospheric Research (TIGER) Program go?

    Science.gov (United States)

    Schmidtke, G.; Avakyan, S. V.; Berdermann, J.; Bothmer, V.; Cessateur, G.; Ciraolo, L.; Didkovsky, L.; Dudok de Wit, T.; Eparvier, F. G.; Gottwald, A.; Haberreiter, M.; Hammer, R.; Jacobi, Ch.; Jakowski, N.; Kretzschmar, M.; Lilensten, J.; Pfeifer, M.; Radicella, S. M.; Schäfer, R.; Schmidt, W.; Solomon, S. C.; Thuillier, G.; Tobiska, W. K.; Wieman, S.; Woods, T. N.

    2015-10-01

    At the 10th Thermospheric Ionospheric GEospheric Research (TIGER/COSPAR) symposium held in Moscow in 2014 the achievements from the start of TIGER in 1998 were summarized. During that period, great progress was made in measuring, understanding, and modeling the highly variable UV-Soft X-ray (XUV) solar spectral irradiance (SSI), and its effects on the upper atmosphere. However, after more than 50 years of work the radiometric accuracy of SSI observation is still an issue and requires further improvement. Based on the extreme ultraviolet (EUV) data from the SOLAR/SolACES, and SDO/EVE instruments, we present a combined data set for the spectral range from 16.5 to 105.5 nm covering a period of 3.5 years from 2011 through mid of 2014. This data set is used in ionospheric modeling of the global Total Electron Content (TEC), and in validating EUV SSI modeling. For further investigations the period of 3.5 years is being extended to about 12 years by including data from SOHO/SEM and TIMED/SEE instruments. Similarly, UV data are used in modeling activities. After summarizing the results, concepts are proposed for future real-time SSI measurements with in-flight calibration as experienced with the ISS SOLAR payload, for the development of a space weather camera for observing and investigating space weather phenomena in real-time, and for providing data sets for SSI and climate modeling. Other planned topics are the investigation of the relationship between solar EUV/UV and visible/near-infrared emissions, the impact of X-rays on the upper atmosphere, the development of solar EUV/UV indices for different applications, and establishing a shared TIGER data system for EUV/UV SSI data distribution and real-time streaming, also taking into account the achievements of the FP7 SOLID (First European SOLar Irradiance Data Exploitation) project. For further progress it is imperative that coordinating activities in this special field of solar-terrestrial relations and solar physics is

  13. On the role of ozone in long-term trends in the upper atmosphere-ionosphere system

    Directory of Open Access Journals (Sweden)

    J. Laštovička

    2012-05-01

    Full Text Available Origin of long-term trends in the thermosphere-ionosphere system has been discussed since the beginning of trend studies. The two most prioritized explanations have been those via long-term increase of atmospheric concentration of greenhouse gases and long-term increase of geomagnetic activity throughout the 20th century. Secular changes of the Earth's main magnetic field play an important role in trends in a limited region. Recently, Walsh and Oliver (2011 suggested that the long-term cooling of the upper thermosphere (above 200 km may be due largely to the stratospheric ozone depletion. Here, we show that the role of ozone is very important in the mesosphere and lower thermosphere but not in the upper thermosphere. The suggestion of Walsh and Oliver (2011 is based on historical (before 1988 data from Saint-Santin radar, whereas more recent data do not support their conclusion.

  14. Report of the Ionosphere-Thermosphere-Mesosphere Panel

    Science.gov (United States)

    Szuszczewicz, Edward P.; Killeen, Tim L.; Arnoldy, Roger L.; Brace, Larry H.; Christensen, Andrew B.; Fejer, B.; Heelis, Roderick A.; Keskinen, Michael J.; Maynard, Nelson C.; Mayr, Hans G.

    1991-01-01

    The scientific objectives and mission concept that emerged from the discussions of this panel are presented. The overall scientific theme of this report is the investigation of the ionosphere, thermosphere, and mesosphere (near Earth space environment) as a global, dynamic, and coupled system. Among the specific goals of this area of research are: (1) understanding the consequences of transition between turbulent and laminar flow and collisional and collisionless media; (2) understanding the thermospheric/mesospheric coupling due to gravity wave, tidal, and trace constituent transport processes; (3) understanding the electrodynamical coupling between the thermosphere/ionosphere and magnetosphere; (4) understanding the coupling processes between small scale plasma structures; and (5) determining the real-time evolution of the global ionosphere electric field in response to solar wind and magnetosphere coupling.

  15. Temperature of the thermosphere. [Titan atmospheric model with energy transfer

    Science.gov (United States)

    Strobel, D. L.

    1974-01-01

    The vertical temperature contrast for the thermosphere of Titan is estimated considering heating by absorption of solar energy, energy loss through infrared radiation by polyatomic molecules, and energy transfer by thermal conduction between the regions of energy deposition and loss. Current observational data suggest a CH4/H2 mixing ratio of approximately greater than 1, and a vertical temperature contrast smaller than 10 K. However, it is highly probable that H2 and CH4 are not in equilibrium in the thermosphere if there are large H2 escape rates.

  16. Polarizing Michelson interferometer for measuring thermospheric winds

    Energy Technology Data Exchange (ETDEWEB)

    Bird, J.C.

    1991-01-01

    The Polarizing Atmospheric Michelson Interferometer, PAMI, a new version of the Wide Angle Michelson Interferometer, is used to measure winds in the termosphere. In the polarizing instrument, the optical path difference is changed simply by rotating a polarizing filter external to the interferometer. This allows a very simple scanning mechanism. PAMI is similar to other instruments such as WAMDII that measure thermospheric winds and temperatures, retaining the benefits of high light throughput, while offering advantages including lower cost, simplicity, and portability. The instrument is highly sensitive and thus is designed to be used for field measurements at locations far from city lights. Results are shown from the AIDA observation campaign in Puerto Rico where coordinated observations were made by PAMI along with other optical and radio measurements during April and May 1989. Intensities of the green line layer at 95 km were compared to those observed by several other instruments. For example, MORTI (Mesopause Oxygen Rotational Temperature Imager), a colocated instrument which was looking at the 94 km 867.6 nm molecular oxygen emission. MORTI and PAMI emission rates were found to show the same trends. On the brightest night recorded during April, the zenith emission rate reached over 400 Rayleighs; emission enhancements were sometimes related to auroral events. During the observing period of April 4 to April 11, 1989, most of the observations of the 94 km airglow were after midnight where the winds were found to be generally towards the north east at about 50 to 100 m/s. During auroral activity this wind vector always turned counterclockwise, towards the west. During the nights of May 2 and May 6 these wind vectors follow a wave-like variation in magnitude and direction. It is concluded that auroral activity changes the global circulation in a way that sometimes transports increased amounts of oxygen atoms over Arecibo.

  17. Transfer function analysis of thermospheric perturbations

    Science.gov (United States)

    Mayr, H. G.; Harris, I.; Varosi, F.; Herrero, F. A.; Spencer, N. W.

    1986-01-01

    Applying perturbation theory, a spectral model in terms of vectors spherical harmonics (Legendre polynomials) is used to describe the short term thermospheric perturbations originating in the auroral regions. The source may be Joule heating, particle precipitation or ExB ion drift-momentum coupling. A multiconstituent atmosphere is considered, allowing for the collisional momentum exchange between species including Ar, O2, N2, O, He and H. The coupled equations of energy, mass and momentum conservation are solved simultaneously for the major species N2 and O. Applying homogeneous boundary conditions, the integration is carred out from the Earth's surface up to 700 km. In the analysis, the spherical harmonics are treated as eigenfunctions, assuming that the Earth's rotation (and prevailing circulation) do not significantly affect perturbations with periods which are typically much less than one day. Under these simplifying assumptions, and given a particular source distribution in the vertical, a two dimensional transfer function is constructed to describe the three dimensional response of the atmosphere. In the order of increasing horizontal wave numbers (order of polynomials), this transfer function reveals five components. To compile the transfer function, the numerical computations are very time consuming (about 100 hours on a VAX for one particular vertical source distribution). However, given the transfer function, the atmospheric response in space and time (using Fourier integral representation) can be constructed with a few seconds of a central processing unit. This model is applied in a case study of wind and temperature measurements on the Dynamics Explorer B, which show features characteristic of a ringlike excitation source in the auroral oval. The data can be interpreted as gravity waves which are focused (and amplified) in the polar region and then are reflected to propagate toward lower latitudes.

  18. Winds in the high-latitude lower thermosphere: Dependence on the interplanetary magnetic field

    DEFF Research Database (Denmark)

    Richmond, A.D.; Lathuillere, C.; Vennerstrøm, Susanne

    2003-01-01

    [1] Wind observations in the summertime lower thermosphere at high southern latitudes, measured by the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite, are statistically analyzed in magnetic coordinates and correlated with the interplanetary magnetic field (IMF......) to determine influences of IMF-dependent ionospheric convection on the winds. Effects are clearly detectable down to 105 km altitude. Above 125 km the wind patterns show considerable similarity with ionospheric convection patterns, and the speed of the averaged neutral wind in the polar cap often exceeds 300 m....../s. The correlation between the IMF B-z component and the diurnal harmonic of the winds is generally best when the IMF is averaged over the preceding 1-4.5 hours. The magnetic-zonal-mean zonal wind below 120 km correlates best with the IMF B-y component when the latter is averaged over approximately the preceding 20...

  19. Role of solar influences on geomagnetosphere and upper atmosphere

    Science.gov (United States)

    Kumar Tripathi, Arvind

    The Earth's magnetosphere and upper atmosphere can be greatly perturbed by variations in the solar luminosity caused by disturbances on the solar surface. The state of near-Earth space environment is governed by the Sun and is very dynamic on all spatial and temporal scale. The geomagnetic field which protects the Earth from solar wind and cosmic rays is also essential to the evolution of life; its variations can have either direct or indirect effect on human physiology and health state even if the magnitude of the disturbance is small. Geomagnetic disturbances are seen at the surface of the Earth as perturbations in the components of the geomagnetic field, caused by electric currents flowing in the magnetosphere and upper atmosphere. Ionospheric and thermospheric storms also result from the redistribution of particles and fields. Global thermospheric storm winds and composition changes are driven by energy injection at high latitudes. These storm effects may penetrate downwards to the lower thermosphere and may even perturb the mesosphere. Many of the ionospheric changes at mid-latitude can be understood as a response to thermospheric perturbations. The transient bursts of solar energetic particles, often associated with large solar transients, have been observed to have effects on the Earth's middle and lower atmosphere, including the large-scale destruction of polar stratospheric and tropospheric ozone. In the present, we have discussed effect of solar influences on earth's magnetosphere and upper atmosphere that are useful to space weather and global warming, on the basis of various latest studies.

  20. Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

    Science.gov (United States)

    Connor, Hyunju Kim; Zesta, Eftyhia; Fedrizzi, Mariangel; Shi, Yong; Raeder, Joachim; Codrescu, Mihail V.; Fuller-Rowell, Tim J.

    2016-06-01

    The magnetosphere is a major source of energy for the Earth's ionosphere and thermosphere (IT) system. Current IT models drive the upper atmosphere using empirically calculated magnetospheric energy input. Thus, they do not sufficiently capture the storm-time dynamics, particularly at high latitudes. To improve the prediction capability of IT models, a physics-based magnetospheric input is necessary. Here, we use the Open Global General Circulation Model (OpenGGCM) coupled with the Coupled Thermosphere Ionosphere Model (CTIM). OpenGGCM calculates a three-dimensional global magnetosphere and a two-dimensional high-latitude ionosphere by solving resistive magnetohydrodynamic (MHD) equations with solar wind input. CTIM calculates a global thermosphere and a high-latitude ionosphere in three dimensions using realistic magnetospheric inputs from the OpenGGCM. We investigate whether the coupled model improves the storm-time IT responses by simulating a geomagnetic storm that is preceded by a strong solar wind pressure front on August 24, 2005. We compare the OpenGGCM-CTIM results with low-earth-orbit satellite observations and with the model results of Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe). CTIPe is an up-to-date version of CTIM that incorporates more IT dynamics such as a low-latitude ionosphere and a plasmasphere, but uses empirical magnetospheric input. OpenGGCM-CTIM reproduces localized neutral density peaks at ~ 400 km altitude in the high-latitude dayside regions in agreement with in situ observations during the pressure shock and the early phase of the storm. Although CTIPe is in some sense a much superior model than CTIM, it misses these localized enhancements. Unlike the CTIPe empirical input models, OpenGGCM-CTIM more faithfully produces localized increases of both auroral precipitation and ionospheric electric fields near the high-latitude dayside region after the pressure shock and after the storm onset, which in turn

  1. Quantification of Transient Changes of Thermospheric Neutral Density

    Science.gov (United States)

    2014-11-24

    Pedersen conductivity at high latitudes . Based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites...capture more random behavior of the electric field variability. The notable exception to this trend is EOF 11, which captures mid- latitude variations on...AFRL-OSR-VA-TR-2014-0320 Quantification of Transient Changes of Thermospheric Neutral Density Arthur Richmond UNIVERSITY CORPORATION FOR ATMOSPHERIC

  2. Strong thermospheric cooling during the 2009 major stratosphere warming

    NARCIS (Netherlands)

    Liu, H.; Doornbos, E.N.; Yamamoto, M.; Ram, S.T.

    2011-01-01

    Thermospheric density simultaneously observed by the CHAMP and GRACE satellites in both the pre‐dawn and afternoon local time sectors undergoes significant decrease across both hemispheres during the major stratospheric sudden warming (SSW) in January 2009. This decrease is largest in the equatorial

  3. Strong thermospheric cooling during the 2009 major stratosphere warming

    NARCIS (Netherlands)

    Liu, H.; Doornbos, E.N.; Yamamoto, M.; Ram, S.T.

    2011-01-01

    Thermospheric density simultaneously observed by the CHAMP and GRACE satellites in both the pre‐dawn and afternoon local time sectors undergoes significant decrease across both hemispheres during the major stratospheric sudden warming (SSW) in January 2009. This decrease is largest in the equatorial

  4. Mars bevares

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Hendricks, Elbert

    2009-01-01

    2009 er femåret for Mission Mars. I den anledning opridser de to kronikører, far og søn, hvorfor man bør lade planer om en bemandet tur til Mars forblive i skrivebordsskuffen......2009 er femåret for Mission Mars. I den anledning opridser de to kronikører, far og søn, hvorfor man bør lade planer om en bemandet tur til Mars forblive i skrivebordsskuffen...

  5. Herschel/HIFI observations of Mars: first detection of O_2 at submillimetre wavelengths and upper limits on HCl and H_2O_2

    CERN Document Server

    Hartogh, P; Lellouch, E; de Val-Borro, M; Rengel, M; Moreno, R; Medvedev, A S; Sagawa, H; Swinyard, B M; Cavalié, T; Lis, D C; Błęcka, M I; Banaszkiewicz, M; Bockelée-Morvan, D; Crovisier, J; Encrenaz, T; Küppers, M; Lara, L -M; Szutowicz, S; Vandenbussche, B; Bensch, F; Bergin, E A; Billebaud, F; Biver, N; Blake, G A; Blommaert, J A D L; Cernicharo, J; Decin, L; Encrenaz, P; Feuchtgruber, H; Fulton, T; de Graauw, T; Jehin, E; Kidger, M; Lorente, R; Naylor, D A; Portyankina, G; Sánchez-Portal, M; Schieder, R; Sidher, S; Thomas, N; Verdugo, E; Waelkens, C; Whyborn, N; Teyssier, D; Helmich, F; Roelfsema, P; Stutzki, J; LeDuc, H G; Stern, J A

    2010-01-01

    We report on the initial analysis of Herschel/HIFI observations of hydrogen chloride (HCl), hydrogen peroxide (H_2O_2) and molecular oxygen (O_2) in the martian atmosphere performed on 13 and 16 April 2010 (L_s ~ 77{\\deg}). We derived a constant volume mixing ratio of 1400 +/- 120 ppm for O_2 and determined upper limits of 200 ppt for HCl and 2 ppb for H_2O_2. Radiative transfer model calculations indicate that the vertical profile of O_2 may not be constant. Photochemical models find lowest values for H_2O_2 around L_s ~ 75{\\deg} but overestimate the volume mixing ratio compared to our measurements.

  6. Studies on mesosphere, thermosphere and ionosphere from equatorial to mid latitudes - Recent investigations and improvements - Part 1

    Science.gov (United States)

    Kavutarapu, Venkatesh; Pezzopane, Michael

    2017-10-01

    Investigations on mesosphere, thermosphere and ionosphere system are areas of increasing prominence since they are sensitive indicators of climate change and affect satellite-based technologies which have an important role in contemporary life. Compared to the one at high latitudes, the equatorial and low-latitude ionosphere exhibit strong spatio-temporal variability in the presence of really complex electrodynamic processes like among others the Equatorial Ionization Anomaly and the Equatorial Spread-F. In addition to this significant quiet-time variability, space weather events cause severe perturbations of the upper atmosphere through solar wind-magnetosphere-ionosphere coupling. Studies to achieve a comprehensive understanding on global characteristics of the thermosphere-ionosphere system are of vital importance to develop efficient models to meet the accuracy requirements of satellite-based communication and navigation applications. Further, the current 24th solar cycle is associated with several unique features, such as the deep and prolonged minimum, and the lowest maximum of the past hundred years, which triggered an increased interest to understand the upper atmospheric variability under such extreme and peculiar conditions.

  7. Indigenous Fixed Nitrogen on Mars: Implications for Habitability

    Science.gov (United States)

    Stern, J. C.; Sutter, B.; Navarro-Gonzalez, R.; McKay, C. P.; Freissinet, C.; Archer, D., Jr.; Eigenbrode, J. L.; Mahaffy, P. R.; Conrad, P. G.

    2015-12-01

    Nitrate has been detected in Mars surface sediments and aeolian deposits by the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory Curiosity rover (Stern et al., 2015). This detection is significant because fixed nitrogen is necessary for life, a requirement that drove the evolution of N-fixing metabolism in life on Earth. The question remains as to the extent to which a primitive N cycle ever developed on Mars, and whether N is currently being deposited on the martian surface at a non-negligible rate. It is also necessary to consider processes that could recycle oxidized N back into the atmosphere, and how these processes may have changed the soil inventory of N over time. The abundance of fixed nitrogen detected as NO from thermal decomposition of nitrate is consistent with both delivery of nitrate via impact generated thermal shock early in martian history and dry deposition from photochemistry of thermospheric NO, occurring in the present. Processes that could recycle N back into the atmosphere may include nitrate reduction by Fe(II) in aqueous environments on early Mars, impact decomposition, and/or UV photolysis. In order to better understand the history of nitrogen fixation on Mars, we look to cycling of N in Mars analog environments on Earth such as the Atacama Desert and the Dry Valleys of Antarctica. In particular, we examine the ratio of nitrate to perchlorate (NO3-/ClO4-) in these areas compared to those calculated from data acquired on Mars.

  8. Temporal Variability of Waves at the Proton Cyclotron Frequency Upstream from Mars: Implications for Mars Distant Hydrogen Exosphere

    CERN Document Server

    Bertucci, Cesar; Chaufray, Jean-Yves; Gomez, Daniel; Mazelle, Christian; Delva, Magda; Modolo, Ronan; Gonzalez-Galindo, Francisco; Brain, David Andrew

    2013-01-01

    We report on the temporal variability of the occurrence of waves at the local proton cyclotron frequency upstream from the Martian bow shock from Mars Global Surveyor observations during the first aerobraking and science phasing orbit periods. Observations at high southern latitudes during minimum-to-mean solar activity show that the wave occurrence rate is significantly higher around perihelion southern summer solstice and lower around the same hemisphere's spring and autumn equinoxes. A similar trend is observed in the hydrogen (H) exospheric density profiles over the Martian South Pole obtained from a model including UV thermospheric heating effects. In spite of the complexity in the ion pick-up and plasma wave generation and evolution processes, these results support the idea that variations in the occurrence of waves could be used to study the temporal evolution of the distant Martian H corona and its coupling with the thermosphere at altitudes currently inaccessible to direct measurements.

  9. Current understanding of the aeronomy of Mars

    Science.gov (United States)

    Nagy, Andrew F.; Grebowsky, Joseph M.

    2015-12-01

    This paper provides a short overview of our current understanding of the upper atmosphere/ionosphere of Mars including the escaping neutral atmosphere to space that plays a key role in the current state of the Mars upper atmosphere. The proper definition of the word "aeronomy" relates to the upper atmosphere where ionization is important. Currently there is a paucity of measurements of the internal physical structure of the Martian upper atmosphere/ionosphere. Much that we know has been deduced from theoretical models that predict many more things than thus far measured. The newest Mars orbital missions, the US MAVEN and Indian MOM missions, just beginning their science analyses, will provide the measurements needed to fully characterize the aeronomy of Mars.

  10. On the global mean temperature of the thermosphere

    Science.gov (United States)

    Roble, R. G.; Emergy, B. A.

    1983-01-01

    It is pointed out that the global mean temperature structure of the thermosphere above 120 km is primarily maintained by the absorption of solar extreme ultraviolet (EUV) flux at wavelengths less than 1025 A and solar ultraviolet (UV) flux. A number of previous calculations of the global mean temperature profile have determined that it is not possible to obtain agreement between the calculated global mean exospheric temperature and observed values. Since those studies, a considerable amount of new information on this problem has been obtained, including data obtained with the aid of the Atmospheric Explorer satellites. The present investigation is, therefore, concerned with a reexamination of the question whether there is enough solar UV radiation and auroral energy input to maintain the observed global mean temperature structure of the thermosphere above 120 km. It is found that for solar cycle minimum conditions there is an approximate balance between absorbed solar radiation and downward molecular thermal conduction.

  11. Influence of upstream solar wind on thermospheric flows at Jupiter

    CERN Document Server

    Yates, J N; Guio, P

    2010-01-01

    The coupling of Jupiter's magnetosphere and ionosphere plays a vital role in creating its auroral emissions. The strength of these emissions is dependent on the difference in speed of the rotational flows within Jupiter's high-latitude thermosphere and the planet's magnetodisc. Using an azimuthally symmetric global circulation model, we have simulated how upstream solar wind conditions affect the energy and direction of atmospheric flows. In order to simulate the effect of a varying dynamic pressure in the upstream solar wind, we calculated three magnetic field profiles representing compressed, averaged and expanded `middle' magnetospheres. These profiles were then used to solve for the angular velocity of plasma in the magnetosphere. This angular velocity determines the strength of currents flowing between the ionosphere and magnetosphere. We examine the influence of variability in this current system upon the global winds and energy inputs within the Jovian thermosphere. We find that the power dissipated by...

  12. Thermospheric neutral densities derived from Swarm accelerometer and GPS data

    DEFF Research Database (Denmark)

    Doornbos, Eelco; Encarnacao, Joao; van den IJss, Jose;

    approach, affects the possibility of determining densities from the accelerometer measurements of the Swarm A and B satellites. We also investigate the possibility of determining crosswind speeds from Swarm data.In the meantime, we have investigated the possibility of deriving thermosphere neutral density...... affected and most promising data for scientific use. The goal to make the Swarm C accelerometer along-track axis data ready for further processing into level 2 thermosphere density data has now been accomplished, with the help of information on the satellite motion from the GPS tracking as well...... data from the Swarm GPS observations only, with a much lower temporal resolution. We analyse the differences in the data between the three Swarm satellites as well as between the accelerometer-derived and GPS-only-derived densities for Swarm C....

  13. Numerical modelling of the thermosphere-ionosphere coupling during substorm

    Science.gov (United States)

    Korenkov, Yu. N.; Bessarab, F. S.; Klimenko, V. V.; Surotkin, V. A.; Smertin, V. M.

    The numerical calculation results of the thermospheric parameters ([O]/[N_2] ratio and Tn) and critical frequencies of F2-region of ionosphere, foF2, in the global scale for the recovery phase of the substorm are presented. The calculations were executed with the use of the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) was constructed in the Kaliningrad Observatory of the IZMIRAN and modified in the Polar Geophysical Institute. The influences of the global distribution of Joule dissipation on the neutral atmosphere and ionosphere parameters are discussed. It is emphasised that the Joule dissipation in the neutral atmosphere is a main cause of the negative disturbance in the F2 region of the ionosphere.

  14. Emirates Mars Mission (EMM) Overview

    Science.gov (United States)

    Sharaf, Omran; Amiri, Sarah; AlMheiri, Suhail; Alrais, Adnan; Wali, Mohammad; AlShamsi, Zakareyya; AlQasim, Ibrahim; AlHarmoodi, Khuloud; AlTeneiji, Nour; Almatroushi, Hessa; AlShamsi, Maryam; AlAwadhi, Mohsen; McGrath, Michael; Withnell, Pete; Ferrington, Nicolas; Reed, Heather; Landin, Brett; Ryan, Sean; Pramann, Brian

    2017-04-01

    United Arab Emirates (UAE) has entered the space exploration race with the announcement of Emirates Mars Mission (EMM), the first Arab Islamic mission to another planet, in 2014. Through this mission, UAE is to send an unmanned probe, called Hope probe, to be launched in summer 2020 and reach Mars by 2021 to coincide with UAE's 50th anniversary. Through a sequence of subsequent maneuvers, the spacecraft will enter a large science orbit that has a periapsis altitude of 20,000 km, an apoapsis altitude of 43,000 km, and an inclination of 25 degrees. The mission is designed to (1) characterize the state of the Martian lower atmosphere on global scales and its geographic, diurnal and seasonal variability, (2) correlate rates of thermal and photochemical atmospheric escape with conditions in the collisional Martian atmosphere, and (3) characterize the spatial structure and variability of key constituents in the Martian exosphere. These objectives will be met by four investigations with diurnal variability on sub-seasonal timescales which are (1) determining the three-dimensional thermal state of the lower atmosphere, (2) determining the geographic and diurnal distribution of key constituents in the lower atmosphere, (3) determining the abundance and spatial variability of key neutral species in the thermosphere, and (4) determining the three-dimensional structure and variability of key species in the exosphere. EMM will collect these information about the Mars atmospheric circulation and connections through a combination of three distinct instruments that image Mars in the visible, thermal infrared and ultraviolet wavelengths and they are the Emirates eXploration Imager (EXI), the Emirates Mars InfraRed Spectrometer (EMIRS), and the EMM Mars Ultraviolet Spectrometer (EMUS). EMM has passed its Mission Concept Review (MCR), System Requirements Review (SRR), System Design Review (SDR), and Preliminary Design Review (PDR) phases. The mission is led by Emiratis from Mohammed

  15. Climate Change in the Upper Atmosphere

    Science.gov (United States)

    Solomon, S. C.; Liu, H.; Marsh, D. R.; McInerney, J. M.; Qian, L.; Vitt, F.

    2016-12-01

    The terrestrial upper atmosphere is cooling and contracting in response to anthropogenic increases in greenhouse gases. This effect, the opposite of troposheric behavior, is primarily due to infrared radiative cooling by heterogeneous molecules, particularly carbon dioxide, as predicted by Roble and Dickinson in 1989. Upper atmosphere global change has been observed in several ways, most definitively by changes in thermospheric density inferred from satellite drag measurements, or, more controversially, in the possible increase of polar mesospheric clouds. When the TIMED mission launched in 2001, climate change was on its agenda, but surreptitiously, because trends were not expected to be observable during a supposed two-year mission. Now, 15 years later, TIMED has become a pathfinder for climate analysis, particularly through carbon dioxide emissions measured by the SABER instrument. New complexities have emerged, however: the possibility that the carbon dioxide mixing ratio near the mesopause is increasing faster with increasing altitude, and the possibility that solar ultraviolet and geomagnetic activity are exhibiting a decreasing trend over the past one-to-three solar cycles. We have conducted simulations of anthropogenic change in the upper atmosphere using the Whole Atmosphere Community Climate Model - eXtended (WACCM-X), a component of the NCAR Community Earth System Model. The atmospheric response was evaluated using carbon dioxide, methane, and CFC lower boundary conditions from the late 1900's and early 2000's. The results show that the thermosphere should cool at a rate of several degrees per decade under present rates of change, largely driven by the effect of carbon dioxide cooling on thermospheric scale heights. Changes in middle atmosphere temperature, methane, and ozone, have much smaller effects on the thermosphere. Thermospheric cooling causes the ionosphere to also contract to lower altitude, but with small changes induced in NmF2. Whole

  16. Thermospheric zonal temperature gradients observed at low latitudes

    Directory of Open Access Journals (Sweden)

    P. R. Fagundes

    Full Text Available Fabry-Perot interferometer (FPI measurements of thermospheric temperatures from the Doppler widths of the OI 630 nm nightglow emission line have been carried out at Cachoeira Paulista (23° S, 45° W, 16° S dip latitude, Brazil. The east-west components of the thermospheric temperatures obtained on 73 nights during the period from 1988 to 1992, primarily under quiet geomagnetic conditions, were analyzed and are presented in this paper. It was observed that on 67% of these nights, the temperatures in both the east and west sectors presented similar values and nocturnal variations. However, during 33% of the nights, the observed temperatures in the west sector were usually higher than those observed in the east sector, with zonal temperature gradients in the range of 100 K to 600 K, over about an 800 km horizontal distance. Also, in some cases, the observed temperatures in the east and west sectors show different nocturnal variations. One of the possible sources considered for the observed zonal temperature gradients is the influence of gravity wave dissipation effects due to waves that propagate from lower altitudes to thermospheric heights. The observed zonal temperature gradients could also be produced by orographic gravity waves originated away, over the Andes Cordillera in the Pacific Sector, or by dissipation of orographic gravity waves generated over the Mantiqueira Mountains in the Atlantic sector by tropospheric disturbances (fronts and/or subtropical jet streams.

    Key words. Atmospheric composition and structure (air-glow and aurora; thermosphere - composition and chemistry Ionosphere (equatorial ionosphere

  17. Modeling the Thermosphere as a Driven-Dissipative Thermodynamic System

    Science.gov (United States)

    2013-03-01

    Schoendorf, K. D., Siebert, K. D., et al. “Hill Model of Transpolar Potential Saturation: Comparison with MHD Simulation,” Journal of Geophysical...March and 1 December, 2009, where the risk of collision with debris has forced the crew of the International Space Station to take emergency actions to...Solomon, S. C. “A Model of Nitric Oxide in the Lower Thermosphere,” Journal of Geophysical Research, 107: 1205 (2002). Borovsky, J. E., and Denton, M

  18. Comparing High-latitude Ionospheric and Thermospheric Lagrangian Coherent Structures

    Science.gov (United States)

    Wang, N.; Ramirez, U.; Flores, F.; Okic, D.; Datta-Barua, S.

    2015-12-01

    Lagrangian Coherent Structures (LCSs) are invisible boundaries in time varying flow fields that may be subject to mixing and turbulence. The LCS is defined by the local maxima of the finite time Lyapunov exponent (FTLE), a scalar field quantifying the degree of stretching of fluid elements over the flow domain. Although the thermosphere is dominated by neutral wind processes and the ionosphere is governed by plasma electrodynamics, we can compare the LCS in the two modeled flow fields to yield insight into transport and interaction processes in the high-latitude IT system. For obtaining thermospheric LCS, we use the Horizontal Wind Model 2014 (HWM14) [1] at a single altitude to generate the two-dimensional velocity field. The FTLE computation is applied to study the flow field of the neutral wind, and to visualize the forward-time Lagrangian Coherent Structures in the flow domain. The time-varying structures indicate a possible thermospheric LCS ridge in the auroral oval area. The results of a two-day run during a geomagnetically quiet period show that the structures are diurnally quasi-periodic, thus that solar radiation influences the neutral wind flow field. To find the LCS in the high-latitude ionospheric drifts, the Weimer 2001 [2] polar electric potential model and the International Geomagnetic Reference Field 11 [3] are used to compute the ExB drift flow field in ionosphere. As with the neutral winds, the Lagrangian Coherent Structures are obtained by applying the FTLE computation. The relationship between the thermospheric and ionospheric LCS is analyzed by comparing overlapping FTLE maps. Both a publicly available FTLE solver [4] and a custom-built FTLE computation are used and compared for validation [5]. Comparing the modeled IT LCSs on a quiet day with the modeled IT LCSs on a storm day indicates important factors on the structure and time evolution of the LCS.

  19. Stormtime dynamics of the global thermosphere and equatorial ionosphere

    Directory of Open Access Journals (Sweden)

    W. J. Burke

    2009-05-01

    Full Text Available During magnetic storms the development of equatorial plasma bubbles (EPBs and distributions of thermospheric densities are strongly influenced by the histories of imposed magnetospheric electric (εM fields. Periods of intense EPB activity driven by penetration εM fields in the main phase are followed by their worldwide absence during recovery. A new method is applied to estimate global thermospheric energy (Eth budgets from orbit-averaged densities measured by accelerometers on polar-orbiting satellites. During the main phase of storms Eth increases as long as the stormtime εM operates, then exponentially decays toward quiet-time values during early recovery. Some fraction of the energy deposited at high magnetic latitudes during the main phase propagates into the subauroral ionosphere-thermosphere where it affects chemical and azimuthal-wind dynamics well into recovery. We suggest a scenario wherein fossils of main phase activity inhibit full restoration of quiet-time dayside dynamos and pre-reversal enhancements of upward plasma drifts near dusk denying bottomside irregularities sufficient time to grow into EPBs.

  20. A Combined Solar and Geomagnetic Index for Thermospheric Climate

    Science.gov (United States)

    Hunt, Linda; Mlynczak, Marty

    2015-01-01

    Infrared radiation from nitric oxide (NO) at 5.3 Â is a primary mechanism by which the thermosphere cools to space. The SABER instrument on the NASA TIMED satellite has been measuring thermospheric cooling by NO for over 13 years. Physically, changes in NO emission are due to changes in temperature, atomic oxygen, and the NO density. These physical changes however are driven by changes in solar irradiance and changes in geomagnetic conditions. We show that the SABER time series of globally integrated infrared power (Watts) radiated by NO can be replicated accurately by a multiple linear regression fit using the F10.7, Ap, and Dst indices. This fit enables several fundamental properties of NO cooling to be determined as well as their variability with time, permitting reconstruction of the NO power time series back nearly 70 years with extant databases of these indices. The relative roles of solar ultraviolet and geomagnetic processes in determining the NO cooling are derived and shown to be solar cycle dependent. This reconstruction provides a long-term time series of an integral radiative constraint on thermospheric climate that can be used to test climate models.

  1. Thermospheric Response to Solar Wind Electric Field Fluctuations

    Science.gov (United States)

    Perlongo, N. J.; Ridley, A. J.

    2013-12-01

    The electron density of the thermosphere is of paramount importance for radio communications and drag on low altitude satellites, particularly during geomagnetic storms. Transient enhancements of ion velocities and subsequent density and temperature increases frequently occur as a result of storm-driven solar wind electric field fluctuations. Since the Earth's dipole magnetic field is tilted and offset from the center of the planet, significant asymmetries arise that alter the thermospheric response to energy input based upon the time of day of the disturbance. This study utilizes the Global Ionosphere-Thermosphere Model (GITM) to investigate this phenomenon by enhancing the convective electric field for one hour of the day in 22 different simulations. An additional baseline run was conducted with no IMF perturbation. Furthermore, four configurations of Earth's magnetic field were considered, Internal Geomagnetic Reference Field (IGRF), a perfect dipole, a dipole tilted by 10 degrees, and a tilted and offset dipole. These runs were conducted at equinox when the amount of sunlight falling on the different hemispheres is the same. Two additional runs were conducted at the solstices for comparison. It was found that the most geo-effective times are when the poles are pointed towards the sun. The electron density, neutral density and temperature as well as the winds are explored.

  2. Impacts of SABER CO2-based eddy diffusion coefficients in the lower thermosphere on the ionosphere/thermosphere

    Science.gov (United States)

    Salinas, Cornelius Csar Jude H.; Chang, Loren C.; Liang, Mao-Chang; Yue, Jia; Russell, James; Mlynczak, Martin

    2016-12-01

    This work estimates global-mean Kzz using Sounding of the Atmosphere using Broadband Emission Radiometry/Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics monthly global-mean CO2 profiles and a one-dimensional transport model. It is then specified as a lower boundary into the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). Results first show that global-mean CO2 in the mesosphere and lower thermosphere region has annual and semiannual oscillations (AO and SAO) with maxima during solstice seasons along with a primary maximum in boreal summer. Our calculated AO and SAO in global-mean CO2 are then modeled by AO and SAO in global-mean Kzz. It is then shown that our estimated global-mean Kzz is lower in magnitude than the suggested global-mean Kzz from Qian et al. (2009) that can model the observed AO and SAO in the ionosphere/thermosphere (IT) region. However, our estimated global-mean Kzz is similar in magnitude with recent suggestions of global-mean Kzz in models with explicit gravity wave parameterization. Our work therefore concludes that global-mean Kzz from global-mean CO2 profiles cannot model the observed AO and SAO in the IT region because our estimated global-mean Kzz may only be representing eddy diffusion due to gravity wave breaking. The difference between our estimated global-mean Kzz and the global-mean Kzz from Qian et al. (2009) thus represents diffusion and mixing from other nongravity wave sources not directly accounted for in the TIE-GCM lower boundary conditions. These other sources may well be the more dominant lower atmospheric forcing behind the AO and SAO in the IT region.

  3. Properties of cryobrines on Mars

    DEFF Research Database (Denmark)

    Möhlmann, D.; Thomsen, Kaj

    2011-01-01

    Brines, i.e. aqueous salty solutions, increasingly play a role in a better understanding of physics and chemistry (and eventually also putative biology) of the upper surface of Mars. Results of physico-chemical modeling and experimentally determined data to characterize properties of cryobrines...... of potential interest with respect to Mars are described. Eutectic diagrams, the related numerical eutectic values of composition and temperature, the water activity of Mars-relevant brines of sulfates, chlorides, perchlorides and carbonates, including related deliquescence relative humidity, are parameters...... and properties, which are described here in some detail. The results characterize conditions for liquid low-temperature brines ("cryobrines") to evolve and to exist, at least temporarily, on present Mars. (C) 2010 Elsevier Inc. All rights reserved....

  4. Mars Pathfinder

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    First of NASA's Discovery missions. Launched in December 1996 and arrived at Mars on 4 July 1997. Mainly intended as a technology demonstration mission. Used airbags to cushion the landing on Mars. The Carl Sagan Memorial station returned images of an ancient flood plain in Ares Vallis. The 10 kg Sojourner rover used an x-ray spectrometer to study the composition of rocks and travelled about 100 ...

  5. Exploring Mars

    Science.gov (United States)

    Breuil, Stéphanie

    2016-04-01

    Mars is our neighbour planet and has always fascinated humans as it has been seen as a potential abode for life. Knowledge about Mars is huge and was constructed step by step through numerous missions. It could be difficult to describe these missions, the associated technology, the results, the questions they raise, that's why an activity is proposed, that directly interests students. Their production is presented in the poster. Step 1: The main Mars feature and the first Mars explorations using telescope are presented to students. It should be really interesting to present "Mars Canals" from Percival Lowell as it should also warn students against flawed interpretation. Moreover, this study has raised the big question about extra-terrestrial life on Mars for the first time. Using Google Mars is then a good way to show the huge knowledge we have on the planet and to introduce modern missions. Step 2: Students have to choose and describe one of the Mars mission from ESA and NASA. They should work in pairs. Web sites from ESA and NASA are available and the teacher makes sure the main missions will be studied. Step 3: Students have to collect different pieces of information about the mission - When? Which technology? What were the main results? What type of questions does it raise? They prepare an oral presentation in the form they want (role play, academic presentation, using a poster, PowerPoint). They also have to produce playing cards about the mission that could be put on a timeline. Step 4: As a conclusion, the different cards concerning different missions are mixed. Groups of students receive cards and they have to put them on a timeline as fast as possible. It is also possible to play the game "timeline".

  6. Simultaneous ground-based thermospheric wind measurements using Doppler asymmetric spatial heterodyne spectroscopy (DASH) and Fabry-Perot Interferometry

    Science.gov (United States)

    Englert, C. R.; Harlander, J. M.; Meriwether, J. W.; Brown, C. M.; Drob, D. P.; Emmert, J. T.; Castelaz, M.; Roesler, F. L.

    2011-12-01

    The concept of Doppler Asymmetric Spatial Heterodyne (DASH) instruments to measure upper atmospheric winds was initially published in 2006. The DASH approach is identical to the concept of Spatial Heterodyne Spectroscopy (SHS) except that one interferometer arm includes an additional fixed optical path offset, similar to the phase stepping Michelson technique which was used for the WINDII (Wind Imaging Interferometer) experiment. The advantages of DASH include having no moving parts, high sensitivity, and the ability to simultaneously observe multiple isolated emission lines, including a known light source for real time calibration. Since it was first proposed, the development of the DASH technique has progressed significantly. Major milestones include a proof of concept in the laboratory, the design, fabrication and test of a monolithic DASH interferometer for the thermospheric red line (O I 630nm), and initial ground based thermospheric wind measurements using this interferometer. To further increase the technical readiness level (TRL) of DASH for a future satellite instrument, we have conducted coordinated measurements with a DASH prototype and Fabry-Perot interferometer (FPI) from the Pisgah Astronomical Research Institute in North Carolina in the summer of 2011. We will present a comparison of the two experimental data sets and examine how they compare with the empirical horizontal wind model HWM-07.

  7. The impact of planetary-scale waves upon Venus' thermal structure in the thermosphere based upon VTGCM simulation

    Science.gov (United States)

    Brecht, Amanda; Bougher, Stephen W.; Parkinson, Chris; Shields, Drew; Liu, Hanli

    2016-10-01

    Observations of the Venusian thermal structure have been conducted by Venus Express (VEx) and its multiple instruments (i.e. SOIR, SPICAV, and VIRTIS). These VEx observations are being combined with ground based observations to create a single comprehensive database. Thus far, these observations are continuing to reveal the significant variability of Venus' upper atmosphere structure, thereby motivating an analysis of the driver(s) of this variability. A likely driver of this variability is wave deposition. Evidence of waves has been observed, but these waves have not been completely analyzed to understand how and where they are important.The Venus Thermospheric General Circulation Model (VTGCM) will be utilized to examine the role planetary-scale waves play in driving Venus' thermosphere structure and variability (~80 – 200 km). Planetary-scale waves (Kelvin and Rossby waves) have been incorporated at the lower boundary of the VTGCM. The atmospheric response to these waves will be analyzed and presented. Specifically, the simulated thermal structure will be presented with and without planetary scale waves (e.g. Kelvin and Rossby waves) to (1) characterize the magnitude of change; structural change; and location of greatest impact and (2) compare with VEx and ground based observations. Since the thermal structure is strongly dependent on the global circulation, the corresponding wind and density distributions (e.g. CO2 and CO) will also be presented.

  8. Intraannual variability of tides in the thermosphere from model simulations and in situ satellite observations

    NARCIS (Netherlands)

    Häusler, K.; Hagan, M.E.; Forbes, J.M.; Zhang, X.; Doornbos, E.; Bruinsma, S.; Lu, G.

    2015-01-01

    In this paper, we provide insights into limitations imposed by current satellite-based strategies to delineate tidal variability in the thermosphere, as well as the ability of a state-of-the-art model to replicate thermospheric tidal determinations. Toward this end, we conducted a year-long thermosp

  9. Wave coupling between the lower and middle thermosphere as viewed from TIMED and GOCE

    NARCIS (Netherlands)

    Gasperini, F.; Forbes, J.M.; Doornbos, E.N.; Bruinsma, S.L.

    2015-01-01

    Vertical coupling between the lower and middle thermosphere due to the eastward propagating diurnal tide with zonal wave number 3 (DE3) and the 3.5 day ultra-fast Kelvin Wave (UFKW) is investigated using Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics-Sounding of the Atmosphere using B

  10. The Small Mars System

    Science.gov (United States)

    Fantino, E.; Grassi, M.; Pasolini, P.; Causa, F.; Molfese, C.; Aurigemma, R.; Cimminiello, N.; de la Torre, D.; Dell'Aversana, P.; Esposito, F.; Gramiccia, L.; Paudice, F.; Punzo, F.; Roma, I.; Savino, R.; Zuppardi, G.

    2017-08-01

    The Small Mars System is a proposed mission to Mars. Funded by the European Space Agency, the project has successfully completed Phase 0. The contractor is ALI S.c.a.r.l., and the study team includes the University of Naples ;Federico II;, the Astronomical Observatory of Capodimonte and the Space Studies Institute of Catalonia. The objectives of the mission are both technological and scientific, and will be achieved by delivering a small Mars lander carrying a dust particle analyser and an aerial drone. The former shall perform in situ measurements of the size distribution and abundance of dust particles suspended in the Martian atmosphere, whereas the latter shall demonstrate low-altitude flight in the rarefied planetary environment. The mission-enabling technology is an innovative umbrella-like heat shield, known as IRENE, developed and patented by ALI. The mission is also a technological demonstration of the shield in the upper atmosphere of Mars. The core characteristics of SMS are the low cost (120 M€) and the small size (320 kg of wet mass at launch, 110 kg at landing), features which stand out with respect to previous Mars landers. To comply with them is extremely challenging at all levels, and sets strict requirements on the choice of the materials, the sizing of payloads and subsystems, their arrangement inside the spacecraft and the launcher's selection. In this contribution, the mission and system concept and design are illustrated and discussed. Special emphasis is given to the innovative features and to the challenges faced in the development of the work.

  11. The DYNAMO Orbiter Project: High Resolution Mapping of Gravity/Magnetic Fields and In Situ Investigation of Mars Atmospheric Escape

    Science.gov (United States)

    Smrekar, S.; Chassefiere, E.; Forget, F.; Reme, H.; Mazelle, C.; Blelly, P. -L.; Acuna, M.; Connerney, J.; Purucker, M.; Lin, R.

    2000-01-01

    Dynamo is a small Mars orbiter planned to be launched in 2005 or 2007, in the frame of the NASA/CNES Mars exploration program. It is aimed at improving gravity and magnetic field resolution, in order to better understand the magnetic, geologic and thermal history of Mars, and at characterizing current atmospheric escape, which is still poorly constrained. These objectives are achieved by using a low periapsis orbit, similar to the one used by the Mars Global Surveyor spacecraft during its aerobraking phases. The proposed periapsis altitude for Dynamo of 120-130 km, coupled with the global distribution of periapses to be obtained during one Martian year of operation, through about 5000 low passes, will produce a magnetic/gravity field data set with approximately five times the spatial resolution of MGS. Low periapsis provides a unique opportunity to investigate the chemical and dynamical properties of the deep ionosphere, thermosphere, and the interaction between the atmosphere and the solar wind, therefore atmospheric escape, which may have played a crucial role in removing atmosphere, and water, from the planet. There is much room for debate on the importance of current atmosphere escape processes in the evolution of the Martian atmosphere, as early "exotic" processes including hydrodynamic escape and impact erosion are traditionally invoked to explain the apparent sparse inventory of present-day volatiles. Yet, the combination of low surface gravity and the absence of a substantial internally generated magnetic field have undeniable effects on what we observe today. In addition to the current losses in the forms of Jeans and photochemical escape of neutrals, there are solar wind interaction-related erosion mechanisms because the upper atmosphere is directly exposed to the solar wind. The solar wind related loss rates, while now comparable to those of a modest comet, nonetheless occur continuously, with the intriguing possibility of important cumulative and

  12. Mapping thermospheric winds in the auroral zone

    Science.gov (United States)

    Conde, M.; Smith, R. W.

    A new all-sky imaging Fabry-Perot (ASIFP) spectrometer has been developed for ground-based mapping of upper atmospheric wind and temperature fields in the auroral zone. Although several other ASIFP spectrometers exist for atmospheric studies [Rees et al., 1984; Sekar et al., 1993; Biondi et al., 1995] these instruments have all operated with etalons of fixed optical gap, a method potentially subject to errors in the presence of auroral intensity gradients. In this instrument the etalon plate spacing is scanned periodically over one order of interference and each photon detected is assigned to a wavelength interval which is determined from both its arrival location on the detector and the etalon plate spacing prevailing at the detection time. Spectra accumulated this way are not distorted by spatial intensity gradients. Preliminary λ630 nm observations were made during the winter of 1994/95 from Poker Flat Research Range, Alaska. To illustrate some of the features we have observed in this study we present line-of-sight wind estimates derived for the night of December 7, 1994. The background wind matches averages presented previously by Sica et al. [1986] and is consistent with winds driven principally by momentum deposition from ionospheric plasma convection through ion-drag. Smaller scale curvature and divergence features are also discernable and are discussed.

  13. Mars at Ls 137o

    Science.gov (United States)

    2006-01-01

    13 November 2006 These images capture what Mars typically looks like in mid-afternoon at Ls 137o. In other words, with the exception of occasional differences in weather and polar frost patterns, this is what the red planet looks like this month (November 2006). Six views are shown, including the two polar regions. These are composites of 24-26 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global mapping images acquired at red and blue wavelengths. The 'hole' over the south pole is an area where no images were obtained, because this polar region is enveloped in wintertime darkness. Presently, it is summer in the northern hemisphere and winter in the southern hemisphere. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Northern summer/southern winter begins at Ls 90o, northern autumn/southern spring start at Ls 180o, and northern winter/southern summer begin at Ls 270o. Ls 137o occurs in the middle of this month (November 2006). The pictures show how Mars appeared to the MOC wide angle cameras at a previous Ls 137o in March 2001. The six views are centered on the Tharsis region (upper left), Acidalia and Mare Eyrthraeum (upper right), Syrtis Major and Hellas (middle left), Elysium and Mare Cimmeria (middle right), the north pole (lower left), and the south pole (lower right).

  14. Mars at Ls 121o

    Science.gov (United States)

    2006-01-01

    1 October 2006 These images capture what Mars typically looks like in mid-afternoon at L s 121o. In other words, with the exception of occasional differences in weather and polar frost patterns, this is what the red planet looks like this month (October 2006). Six views are shown, including the two polar regions. These are composites of 24-26 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global mapping images acquired at red and blue wavelengths. The 'hole' over the south pole is an area where no images were obtained, because this polar region is enveloped in wintertime darkness. Presently, it is summer in the northern hemisphere and winter in the southern hemisphere. Ls, solar longitude, a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Northern summer/southern winter begins at Ls 90o, northern autumn/southern spring start at Ls 180o, and northern winter/southern summer begin at Ls 270o. Ls 121o occurs in the middle of this month (October 2006). The pictures show how Mars appeared to the MOC wide angle cameras at a previous Ls 121o in February 2001. The six views are centered on the Tharsis region (upper left), Acidalia and Mare Eyrthraeum (upper right), Syrtis Major and Hellas (middle left), Elysium and Mare Cimmeria (middle right), the north pole (lower left), and the south pole (lower right).

  15. Lasers and the Dynamic Mesosphere/Thermosphere of Venus

    Science.gov (United States)

    Kostiuk, Theodor; Fast, Kelly E.; Livengood, Timothy A.; Schmuelling, Frank; Hewagama, Tilak; Annen, John; Buhl, David; Sonnabend, Guido; Sornig, Manuela; Kroetz, Peter; Goldstein, Jeffrey

    2010-01-01

    A review of ground based mid-infrared uniquely high spectral. resolution measurements of Venus dynamics, temperature, and chemistry will be presented. The described studies will focus on the use of CO2 absorption features and the discovery- and use of CO2 thermospheric non-thermal emission: lines as probes of Venus' atmosphere, from the cloud tops to approx.120 km in the thermosphere. The first investigations using infrared heterodyne spectroscopy with resolving power lambda/Delta(lambda) approx. 10(exp 6) to measure true emission line profiles and to determine their non-thermal nature and lasing component will be described. The use of the thermospheric non-thermal CO2 emission to directly measure sub-solar to anti-solar winds and zonal circulation near 110 km altitudes on Venus to approx.2 m/s accuracy will also be described. The measured emission lures are also used to obtain global maps of mesospheric/thermospheric kinetic and rotational temperatures as well as to obtain evidence of the natural lasing phenomena. Carbon dioxide absorption features globally probe lower altitudes in the atmosphere and can be used to determine nightside temperatures. Isotopic 13 CO2 absorption lines are used to probe deeper in the atmosphere to measure the sub-solar to anti-solar return flow at altitudes just above the cloud tops. These results provided a model for global circulation in the 65 - 120 km altitude region first proposed by Goldstein (1989, PhD.Thesis, U. Pennsylvania, Philadelphia, USA). Results of similar wind and temperature measurements made in recent years will be compared to earlier results to investigate changes in the circulation and temperatures since approx.1990. The high resolution infrared heterodyne technique was also used to investigate chemical processes above the cloud tops, specifically evidence and constraints on oxygen-based chemistry. Described measurements were made by infrared heterodyne spectroscopy using the Goddard Space Flight Center Infrared

  16. Apparent Detection of Global Anthropogenic Effects Extending Into the Thermosphere

    Science.gov (United States)

    Keating, G. M.; Theriot, M. E.; Akmaev, R. A.; Bougher, S. W.

    2004-05-01

    From a study of long-term orbital decay of Earth satellites, it has been discovered that thermospheric densities have declined substantially since at least 1976. Detection of this decline was first published by Keating et al (2000) in Geophysical Research Letters. They performed an analysis of 5 Earth satellites with periapsis altitudes near 380 km. The study was conducted for conditions near solar minimum to remove the effect of the 11-year solar cycle. Comparisons were made with a standard empirical density model to remove the effects of variations in solar and geomagnetic activity, altitude, season, latitude, time of day, etc. In that article, it was proposed that the cooling trend was caused by anthropogenic effects. Now the data set has been expanded to 14 satellites near 380 km to obtain an improved estimate of the trend and to establish possible variations in the trend. In the new study, the average trend from 1976-1996 is found to be minus 10.3 plus or minus 1.2 percent. This is in accord with the 2000 paper, which gave an average trend of minus 9.8 plus or minus 2.5 percent. The new results show statistically insignificant differences between the trend at low and high latitudes indicating a global response with no significant correlation to geomagnetic activity variations. The results appear to be in accord with theoretical model estimates for the response of the thermosphere to increases in CO2 and CH4 predicted by Roble and Dickinson (1989), Rishbeth and Roble (1992), and Akmaev and Formichev (2000). A paper by Emmert et al (2004) using a similar approach of studying the orbital decay from 27 satellites qualitatively confirms the downward trend originally discovered in the 2000 paper. All 27 of the satellites they studied indicated a downward trend. Twenty of the 27 satellites experienced a decrease in thermospheric density at somewhat higher altitudes, between 500 and 700 km. It is estimated that CO2 will double before the end of this century

  17. Mar Capeans

    CERN Multimedia

    2017-01-01

    Mar Capeans, CERN researcher, answers the question to "What can we do in the world of sciences and innovation to make visible the invisible?". This piece belongs to a series of videos made by the Spanish Aquae Foundation, a supporter of the CERN & Society Foundation.

  18. Mar adentro

    OpenAIRE

    Florián Guerrero, Mayra

    2014-01-01

    La bravura del mar destruyó primero las canchas de fútbol, luego se tragó casas y finalmente las playas. El otrora balneario exclusivo de Buenos Aires, donde se fundó el famoso restaurant Morillas en los años 40, es ahora un tímido recuerdo en medio del chocar incesante de las olas.

  19. Investigation of the density wave activity in the thermosphere above 220 KM

    Science.gov (United States)

    Illés-Almár, E.; Almár, I.; Bencze, P.

    Based on CACTUS (Capteur Accélérométrique Capacitif Triaxial Ultra Sensible) microaccelerometer measurements it has been demonstrated that - after taking into account all effects included in the MSIS'86=CIRA'86 (COSPAR, 1988) model - there are residual fluctuations in the density of the upper atmosphere much larger than that the accuracy of the measurements can account for. These fluctuations are attributed to some kind of wave activity (Illés-Almár, 1993, Illés-Almár et al. 1996a). The average deviations from a model are considered as a measure of the amplitude of the waves in the atmosphere and are analysed as a function of geomagnetic coordinates, altitude and local solar time, in order to identify possible wave sources either in the lower lying atmosphere or in the thermosphere/ionosphere system. As a first step, the present investigation intends to make a map of the wave pattern by this method.

  20. The 30 cm radio flux as a solar proxy for thermosphere density modelling

    Directory of Open Access Journals (Sweden)

    Dudok de Wit Thierry

    2017-01-01

    Full Text Available The 10.7 cm radio flux (F10.7 is widely used as a proxy for solar UV forcing of the upper atmosphere. However, radio emissions at other centimetric wavelengths have been routinely monitored since the 1950 s, thereby offering prospects for building proxies that may be better tailored to space weather needs. Here we advocate the 30 cm flux (F30 as a proxy that is more sensitive than F10.7 to longer wavelengths in the UV and show that it improves the response of the thermospheric density to solar forcing, as modelled with DTM (Drag Temperature Model. In particular, the model bias drops on average by 0–20% when replacing F10.7 by F30; it is also more stable (the standard deviation of the bias is 15–40% smaller and the density variation at the the solar rotation period is reproduced with a 35–50% smaller error. We compare F30 to other solar proxies and discuss its assets and limitations.

  1. Multi-Periodic Auroral and Thermospheric Variations in 2006

    Directory of Open Access Journals (Sweden)

    Yongliang Zhang

    2013-01-01

    Full Text Available A data survey reveals multiple periodic variations in auroral hemispheric power (HP and thermospheric composition (O/N2 in 2006. The periods include 27, 13 - 14, 9, and 6.7 days. These periods of 13 - 14, 9 and 6.7 days are essentially the harmonics of the 27-day solar rotation. Similar multi-periodicities were found in the dayside magnetic merging rate (MMR (Newell et al. 2007 which depends upon solar wind speed (V, magnitude (BT and clock angle (θc of interplanetary magnetic field (IMF. A high correlation coefficient (0.93 between MMR and HP indicates MMR is the driver of the periodic variations. While high solar wind speed associated with coronal holes plays an important role in the HP variations, IMF BT is equally important. The term [BT2/3sin8/3(θc/2] is even more important as its correlation coefficient with HP is higher than that for BT or solar wind speed. Nevertheless, MMR has the highest correlation with HP. Similar results were seen in the 2005 data where the 9-day variation is dominant. These results indicate that both solar wind speed and IMF conditions are required for accurate specification of periodic variations in aurora hemispheric power and thermosphere composition.

  2. Polar heating in Saturn's thermosphere

    Directory of Open Access Journals (Sweden)

    C. G. A. Smith

    2005-10-01

    Full Text Available A 3-D numerical global circulation model of the Kronian thermosphere has been used to investigate the influence of polar heating. The distributions of temperature and winds resulting from a general heat source in the polar regions are described. We show that both the total energy input and its vertical distribution are important to the resulting thermal structure. We find that the form of the topside heating profile is particularly important in determining exospheric temperatures. We compare our results to exospheric temperatures from Voyager occultation measurements (Smith et al., 1983; Festou and Atreya, 1982 and auroral H3+ temperatures from ground-based spectroscopic observations (e.g. Miller et al., 2000. We find that a polar heat source is consistent with both the Smith et al. determination of T~400 K at ~30° N and auroral temperatures. The required heat source is also consistent with recent estimates of the Joule heating rate at Saturn (Cowley et al., 2004. However, our results show that a polar heat source can probably not explain the Festou and Atreya determination of T~800 K at ~4° N and the auroral temperatures simultaneously.

    Keywords. Ionosphere (Planetary ionosphere – Magnetospherica physics (Planetary magnetospheres – Meterology and atmospheric dynamics (Thermospheric dynamics

  3. Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

    Directory of Open Access Journals (Sweden)

    Connor Hyunju Kim

    2016-01-01

    Full Text Available The magnetosphere is a major source of energy for the Earth’s ionosphere and thermosphere (IT system. Current IT models drive the upper atmosphere using empirically calculated magnetospheric energy input. Thus, they do not sufficiently capture the storm-time dynamics, particularly at high latitudes. To improve the prediction capability of IT models, a physics-based magnetospheric input is necessary. Here, we use the Open Global General Circulation Model (OpenGGCM coupled with the Coupled Thermosphere Ionosphere Model (CTIM. OpenGGCM calculates a three-dimensional global magnetosphere and a two-dimensional high-latitude ionosphere by solving resistive magnetohydrodynamic (MHD equations with solar wind input. CTIM calculates a global thermosphere and a high-latitude ionosphere in three dimensions using realistic magnetospheric inputs from the OpenGGCM. We investigate whether the coupled model improves the storm-time IT responses by simulating a geomagnetic storm that is preceded by a strong solar wind pressure front on August 24, 2005. We compare the OpenGGCM-CTIM results with low-earth-orbit satellite observations and with the model results of Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe. CTIPe is an up-to-date version of CTIM that incorporates more IT dynamics such as a low-latitude ionosphere and a plasmasphere, but uses empirical magnetospheric input. OpenGGCM-CTIM reproduces localized neutral density peaks at ~ 400 km altitude in the high-latitude dayside regions in agreement with in situ observations during the pressure shock and the early phase of the storm. Although CTIPe is in some sense a much superior model than CTIM, it misses these localized enhancements. Unlike the CTIPe empirical input models, OpenGGCM-CTIM more faithfully produces localized increases of both auroral precipitation and ionospheric electric fields near the high-latitude dayside region after the pressure shock and after the storm onset

  4. The inter-annual variability of mesosphere-thermosphere nightglow intensities and their possible coupling with cosmic factors and lower atmosphere climatology

    Science.gov (United States)

    Didebulidze, Goderdzi; Todua, Maya

    2016-07-01

    Possible coupling of the inter-annual/seasonal variations of the mesosphere-thermosphere-ionosphere parameters with cosmic factors and climatology of the lower atmosphere are considered using the nightglow intensity observations from Abastumani (41.75 E; 42.82 E) of (a) the mesopause hydroxyl OH(8-3) bands (maximum luminous layer about 87 km), (b) the thermosphere oxygen green 557.7 nm line (main maximum of luminous layer in the lower thermosphere at about 95 km and small part from the ionosphere F2 region with its peak at about 230-280 km) and (c) the red 630.0 nm line (emitted from the ionosphere F2 region with maximum luminous layer about 230-280 km), which include three eleven-year solar cycles. The observed inter-annual variations of the OH bands and green line, along with their maximal values at spring (March-April) and fall (September-October) equinoxial periods, which are noticed also from other regions, exhibit additional maxima in June. The red line intensity mainly tends to decrease at equinoxial months, while it is maximal in summer and is accompanied by relatively small increase in June (compared to May and July). Maximal values of OH band and green line intensities in June are observed both in maximum and minimum phases of solar activity. This is considered as a manifestation of the features of the upper and lower atmosphere dynamical coupling of this region of Caucasus. The importance of atmospheric gravity waves and tidal motions in the observed specifics of seasonal changes of the lower and upper atmosphere-ionosphere coupling processes is indicated. The seasonal distribution tidal motions like changes of the mesopause and lower thermosphere with 6-12 hours period variations are demonstrated, which could be in situ developed and also coupled with lower atmosphere climatology. The daily mean temperature (with maximum in August) and its changes with heights (maximum in June) can influence cloud covering of this region and thus on generation of

  5. Upper Endoscopy

    Medline Plus

    Full Text Available ... Clinical Topics / Procedures F - Z / Upper Endoscopy (EGD) Upper Endoscopy (EGD) The Latest Practice Guidelines Technology Reviews ... the Safety of Your Endoscopic Procedure Brochure Understanding Upper Endoscopy Brochure Make the Best Choice for Your ...

  6. Statistical analysis of thermospheric gravity waves from Fabry-Perot Interferometer measurements of atomic oxygen

    Directory of Open Access Journals (Sweden)

    E. A. K. Ford

    2008-02-01

    Full Text Available Data from the Fabry-Perot Interferometers at KEOPS (Sweden, Sodankylä (Finland, and Svalbard (Norway, have been analysed for gravity wave activity on all the clear nights from 2000 to 2006. A total of 249 nights were available from KEOPS, 133 from Sodankylä and 185 from the Svalbard FPI. A Lomb-Scargle analysis was performed on each of these nights to identify the periods of any wave activity during the night. Comparisons between many nights of data allow the general characteristics of the waves that are present in the high latitude upper thermosphere to be determined. Comparisons were made between the different parameters: the atomic oxygen intensities, the thermospheric winds and temperatures, and for each parameter the distribution of frequencies of the waves was determined. No dependence on the number of waves on geomagnetic activity levels, or position in the solar cycle, was found. All the FPIs have had different detectors at various times, producing different time resolutions of the data, so comparisons between the different years, and between data from different sites, showed how the time resolution determines which waves are observed. In addition to the cutoff due to the Nyquist frequency, poor resolution observations significantly reduce the number of short-period waves (<1 h period that may be detected with confidence. The length of the dataset, which is usually determined by the length of the night, was the main factor influencing the number of long period waves (>5 h detected. Comparisons between the number of gravity waves detected at KEOPS and Sodankylä over all the seasons showed a similar proportion of waves to the number of nights used for both sites, as expected since the two sites are at similar latitudes and therefore locations with respect to the auroral oval, confirming this as a likely source region. Svalbard showed fewer waves with short periods than KEOPS data for a season when both had the same time resolution data

  7. Optical remote sensing of the thermosphere with HF pumped artificial airglow

    Science.gov (United States)

    Bernhardt, P. A.; Wong, M.; Huba, J. D.; Fejer, B. G.; Wagner, L. S.; Goldstein, J. A.; Selcher, C. A.; Frolov, V. L.; Sergeev, E. N.

    2000-05-01

    Optical emissions excited by high-power radio waves in the ionosphere can be used to measure a wide variety of parameters in the thermosphere. Powerful high-frequency (HF) radio waves produce energetic electrons in the region where the waves reflect in the F region. These hot or suprathermal electrons collide with atomic oxygen atoms to produce localized regions of metastable O(1D) and O(1S) atoms. These metastables subsequently radiate 630.0 and 557.7 nm, respectively, to produce clouds of HF pumped artificial airglow (HPAA). The shapes of the HPAA clouds are determined by the structure of large-scale (~10 km) plasma irregularities that occur naturally or that develop during ionospheric heating. When the HF wave is operated continuously, the motion of the airglow clouds follows the E×B drift of the plasma. When the HF wave is turned off, the airglow clouds decay by collisional quenching and radiation, expand by neutral diffusion, and drift in response to neutral winds. Images of HPAA clouds, obtained using both continuous and stepped radio wave transmissions, are processed to yield the electric fields, neutral wind vectors, and diffusion coefficients in the upper atmosphere. This technique is illustrated using data that were obtained in March 1993 and 1995 at the ionospheric modification facility near Nizhny Novgorod, Russia. Analysis of HPAA clouds yields zonal plasma drifts of 70 m s-1 eastward at night. On the basis of artificial airglow from energetic electrons generated at 260 km the zonal neutral wind speed was estimated to be 96 m s-1 and the O(1D) diffusion coefficient was determined to be between 0.8 and 1.4×1011cm2s-1. The quenched lifetime of the O(1D) was determined to be 29.4 s. The diffusion and quenching rates are directly related to the atomic and molecular concentrations in the thermosphere. Improvements in the remote-sensing technique may be obtained if the intensity of the artificial airglow emissions is increased. High-power radio

  8. Lower thermosphere coupling study: Comparison of observations with predictions of the University College London-Sheffield thermosphere-ionosphere model

    Energy Technology Data Exchange (ETDEWEB)

    Fuller-Rowell, T.J.; Rees, D.; Parish, H.F. (Univ. Coll. London (England)); Virdi, T.S.; Williams, P.J.S. (Univ. Coll. of Wales, Aberystwyth (England)); Johnson, R.M. (Univ. of Michigan, Ann Arbor (USA))

    1991-02-01

    During the first Lower Thermosphere Coupling Study (LTCS), September 21-25 1987, data were recorded from the incoherent scatter radar sites at EISCAT, Millstone Hill, Sondrestrom, and Arecibo. These experimental facilities measured ionospheric parameters (Ne, Te, Ti, and plasma velocity) in the E and the F regions which have been used to determine the E region neutral wind and infer the neutral temperature in the height range 100-150 km. Propagating tides are clearly visible in some of the parameters, and the latitude structure and phase variations with height indicate the presence of at least the (2,2) and (2,4) global tidal Hough modes. The influence of geomagnetic forcing is also clearly present at high latitudes. The University College London-Sheffield University three-dimensional coupled thermosphere-ionosphere model has been used to simulate this period of observation, by imposing tidal forcing at the lower boundary and magnetospheric forcing at high latitudes, in an attempt to interpret and understand the experimental data. Model simulations are able to predict where the signature of a particular tidal mode is likely to be observed in the respective responses of the temperature and wind structure. The numerical simulations predict the range of observed tidal amplitudes at mid and high latitudes, provided the tidal forcing functions imposed near the lower boundary of the model are larger (400 m geopotential height variation) than those inferred from linear tidal models.

  9. Laboratory Study of O2(b1Σ g+, υ = 1) Collisional Removal at Thermospheric Temperatures

    Science.gov (United States)

    Wouters, E. R.; Pejaković, D. A.; Phillips, K. E.; Kalogerakis, K. S.

    2003-12-01

    In the Earth's thermosphere, energy transfer from O(1D) to O2 generates oxygen molecules in the υ = 0 and 1 levels of the O2(b1Σg+) state. The emissions in the O2(b1Σ g+ - X3Σ g-) system (Atmospheric Band) present a major component of the Earth's airglow. Interpretation of the measured intensities of O2 Atmospheric Band emissions can yield altitude profiles of oxygen atom density and local temperature in the lower thermosphere. To achieve this goal accurate laboratory measurements of the collisional removal rate coefficients of O2(b, υ = 1) and their temperature dependence are essential. Atmospheric observations suggest that the relevant colliders for the removal of O2(b, υ = 1) in the lower thermosphere are O2 and O(3P). We report measurements of the rate coefficients for the collisional removal of O2(b, υ = 1) by O2, N2, and CO2, at temperatures in the range 300--1000 K. A state-specific two-laser technique is used, in which the visible output of the first laser directly excites O2 to O2(b, υ = 1), and the ultraviolet output of the second laser probes the O2(b, υ = 1) population by resonantly enhanced multiphoton ionization via the υ= 4 level of the d1Π g Rydberg state. The temporal evolution of the O2(b, υ = 1) population is monitored by varying the time delay between the two laser pulses. The rate coefficient of the collisional removal of O2(b, υ = 1) by O2 increases monotonically with temperature from about 1.5 x 10-11 cm3 s-1 to about 6*E-11 cm3 s-1 in the range 300--1000 K. Experiments with colliders N2 and CO2 determine the upper limits for the removal rate coefficients of O2(b, υ = 1) by N2 and CO2 to be 2 orders of magnitude smaller. This work extends previous studies of O2(b, υ = 1) at room and low temperatures.1,2 We are currently planning experiments to investigate the collisional removal of O2(b, υ = 1) by O atoms. This study was supported by the NSF's Grant ATM-0209229. The participation of K. Phillips in this project was funded by

  10. Quasi 16-day oscillation in the mesosphere and lower thermosphere

    Science.gov (United States)

    Forbes, J. M.; Hagan, M. E.; Miyahara, S.; Vial, F.; Manson, A. H.; Meek, C. E.; Portnyagin, Y. I.

    1995-05-01

    A quasi-16-day wave in the mesosphere and lower thermosphere is investigated through analyses of radar data during January/February 1979 and through numerical simulations for various background wind conditions. Previous workers have examined about 19 days of tropospheric and stratospheric data during January 10-28, 1979, and present conflicting evidence as to whether a large westward propagating wavenumber 1 oscillation observed during this period can be identified in terms of the second symmetric Rossby normal mode of zonal wavenumber 1, commonly referred to as the ``16-day wave.'' In the present work we have applied spectral analysis techniques to meridional and zonal winds near 95 km altitude obtained from radar measurements over Obninsk, Russia (54°N, 38°E) and Saskatoon, Canada (52°N, 107°W). These data reveal oscillations of the order of +/-10 m s-1 with a period near 16 days as well as waves with periods near 5 and 10 days. These periodicities all correspond to expected resonant frequencies of atmospheric disturbances associated with westward propagating free Rossby modes of zonal wavenumber 1. Numerical simulations are performed which demonstrate that the 95-km measurements of the 16-day wave are consistent with upward extension of the oscillation determined from the tropospheric and stratospheric data. Noteworthy features of the model in terms of its applicability in the mesosphere/lower thermosphere regime are explicit inclusion of eddy and molecular diffusion of heat and momentum and realistic distributions of mean winds, especially between 80 and 100 km. The latter include a westerly wind regime above the summer easterly mesospheric jet, thus providing a ducting channel enabling interhemispheric penetration of the winter planetary wave disturbance. This serves to explain the appearance of a quasi-16-day wave recently reported in the high-latitude summer mesopause (Williams and Avery, 1992). However, the efficiency of this interhemispheric coupling

  11. Seasonal effects in the ionosphere-thermosphere response to the precipitation and field-aligned current variations in the cusp region

    Directory of Open Access Journals (Sweden)

    A. A. Namgaladze

    Full Text Available The seasonal effects in the thermosphere and ionosphere responses to the precipitating electron flux and field-aligned current variations, of the order of an hour in duration, in the summer and winter cusp regions have been investigated using the global numerical model of the Earth's upper atmosphere. Two variants of the calculations have been performed both for the IMF By < 0. In the first variant, the model input data for the summer and winter precipitating fluxes and field-aligned currents have been taken as geomagnetically symmetric and equal to those used earlier in the calculations for the equinoctial conditions. It has been found that both ionospheric and thermospheric disturbances are more intensive in the winter cusp region due to the lower conductivity of the winter polar cap ionosphere and correspondingly larger electric field variations leading to the larger Joule heating effects in the ion and neutral gas temperature, ion drag effects in the thermospheric winds and ion drift effects in the F2-region electron concentration. In the second variant, the calculations have been performed for the events of 28–29 January, 1992 when precipitations were weaker but the magnetospheric convection was stronger than in the first variant. Geomagnetically asymmetric input data for the summer and winter precipitating fluxes and field-aligned currents have been taken from the patterns derived by combining data obtained from the satellite, radar and ground magnetometer observations for these events. Calculated patterns of the ionospheric convection and thermospheric circulation have been compared with observations and it has been established that calculated patterns of the ionospheric convection for both winter and summer hemispheres are in a good agreement with the observations. Calculated patterns of the thermospheric circulation are in a good agreement with the average circulation for the Southern (summer Hemisphere obtained

  12. Thermospheric density model biases at the 23rd sunspot maximum

    Science.gov (United States)

    Pardini, C.; Moe, K.; Anselmo, L.

    2012-07-01

    Uncertainties in the neutral density estimation are the major source of aerodynamic drag errors and one of the main limiting factors in the accuracy of the orbit prediction and determination process at low altitudes. Massive efforts have been made over the years to constantly improve the existing operational density models, or to create even more precise and sophisticated tools. Special attention has also been paid to research more appropriate solar and geomagnetic indices. However, the operational models still suffer from weakness. Even if a number of studies have been carried out in the last few years to define the performance improvements, further critical assessments are necessary to evaluate and compare the models at different altitudes and solar activity conditions. Taking advantage of the results of a previous study, an investigation of thermospheric density model biases during the last sunspot maximum (October 1999 - December 2002) was carried out by analyzing the semi-major axis decay of four satellites: Cosmos 2265, Cosmos 2332, SNOE and Clementine. Six thermospheric density models, widely used in spacecraft operations, were analyzed: JR-71, MSISE-90, NRLMSISE-00, GOST-2004, JB2006 and JB2008. During the time span considered, for each satellite and atmospheric density model, a fitted drag coefficient was solved for and then compared with the calculated physical drag coefficient. It was therefore possible to derive the average density biases of the thermospheric models during the maximum of the 23rd solar cycle. Below 500 km, all the models overestimated the average atmospheric density by amounts varying between +7% and +20%. This was an inevitable consequence of constructing thermospheric models from density data obtained by assuming a fixed drag coefficient, independent of altitude. Because the uncertainty affecting the drag coefficient measurements was about 3% at both 200 km and 480 km of altitude, the calculated air density biases below 500 km were

  13. Martian thermosphere-exosphere temperatures from SPICAM dayglow measurements

    Science.gov (United States)

    Stiepen, A.; Gérard, J.-C.; Bougher, S.; Montmessin, F.

    2013-09-01

    We analyze the ultraviolet dayglow in the atmosphere of Mars through CO2+ and CO Cameron emissions. These emissions are accumulated on a large dataset of dayside grazing limb performed by the Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) instrument on board the Mars Express spacecraft. The temperature of the Martian high atmosphere can be retrieved from these limb emission profiles. Its variability with season, latitude, solar activity and the crustal magnetic field is discussed. We use a one-dimensional chemical-diffusive model to retrieve the main features of the emissions and constrain the temperature and density vertical profiles of the main components of the Martian atmosphere.

  14. Thermospheric recovery during the 5 April 2010 geomagnetic storm

    Science.gov (United States)

    Sheng, Cheng; Lu, Gang; Solomon, Stanley C.; Wang, Wenbin; Doornbos, Eelco; Hunt, Linda A.; Mlynczak, Martin G.

    2017-04-01

    Thermospheric temperature and density recovery during the 5 April 2010 geomagnetic storm has been investigated in this study. Neutral density recovery as revealed by Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) simulations was slower than observations from GOCE, CHAMP, and GRACE satellites, suggesting that the cooling processes may not be fully represented in the model. The NO radiative cooling rate in TIEGCM was also compared with TIMED/SABER measurements along satellite orbits during this storm period. It was found that the model overestimated the NO cooling rate at low latitudes and underestimated it at high latitudes. The effects of particle precipitation on NO number density and NO cooling rate at high latitudes were examined in detail. Model experiments showed that while NO number density and NO cooling rate do change with different specifications of the characteristic energy of auroral precipitating electrons, neutral temperature and density recovery remain more or less the same. The reaction rates of key NO chemistry were tested as well, and the NO number density between 110 and 150 km was found to be very sensitive to the reaction rate of N(2D) + O2 → NO + O. A temperature-dependent reaction rate for this reaction proposed by Duff et al. (2003) brought the TIEGCM NO cooling rate at high latitudes closer to the SABER observations. With the temperature-dependent reaction rate, the neutral density recovery time became quite close to the observations in the high-latitude Southern Hemisphere. But model-data discrepancies still exist at low latitudes and in the Northern Hemisphere, which calls for further investigation.

  15. Global and Meso-scale Thermospheric Neutral Wind Response to Geomagnetic Storm

    Science.gov (United States)

    Lu, G.; Conde, M.; Doornbos, E.

    2015-12-01

    This paper presents a case study of thermospheric response to the 5 April 2010 geomagnetic storm. The NCAR Thermosphere-Ionosphere-Mesosphere Electrodynamic General Circulation Model (TIMEGCM) is used to investigate thermospheric neutral wind variations during the storm, and the model results are validated through comparison with ground and space based observations. More specifically, we conduct detailed inter-comparison of the winds observed by scanning Doppler imagers (SDI) in Alaska with those derived from the TIMEGCM simulations in order to assess model's ability in reproducing the observed meso-scale wind field. The thermospheric winds obtained from the accelerometers on board the GOCE satellite are also used to validate the simulation results on a global scale. While globally the wind velocity tends to be smaller than ion drift velocity, locally the winds can exceed ion drifts and also blow in the different direction than the ions. We will discuss how the thermospheric winds affect the energetic coupling of the magnetosphere-ionosphere-thermosphere system in terms of Joule heating and field-aligned currents.

  16. Influence of solar variability on the infrared radiative cooling of the thermosphere from 2002 to 2014.

    Science.gov (United States)

    Mlynczak, Martin G; Hunt, Linda A; Mertens, Christopher J; Thomas Marshall, B; Russell, James M; Woods, Thomas; Earl Thompson, R; Gordley, Larry L

    2014-04-16

    Infrared radiative cooling of the thermosphere by carbon dioxide (CO2, 15 µm) and by nitric oxide (NO, 5.3 µm) has been observed for 12 years by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics satellite. For the first time we present a record of the two most important thermospheric infrared cooling agents over a complete solar cycle. SABER has documented dramatic variability in the radiative cooling on time scales ranging from days to the 11 year solar cycle. Deep minima in global mean vertical profiles of radiative cooling are observed in 2008-2009. Current solar maximum conditions, evidenced in the rates of radiative cooling, are substantially weaker than prior maximum conditions in 2002-2003. The observed changes in thermospheric cooling correlate well with changes in solar ultraviolet irradiance and geomagnetic activity during the prior maximum conditions. NO and CO2 combine to emit 7 × 10(18) more Joules annually at solar maximum than at solar minimum. First record of thermospheric IR cooling rates over a complete solar cycleIR cooling in current solar maximum conditions much weaker than prior maximumVariability in thermospheric IR cooling observed on scale of days to 11 years.

  17. Upper-Thermospheric Observations and Neutral-Gas Dynamics at High Latitudes During Solar Maximum.

    Science.gov (United States)

    1987-01-01

    aeasFPIgure 6.5, ecep orB> oniios -40 TO~ -- 12 p . p’ T5 .ww i - IO RFS 5 183 maximum antisunward neutral winds located in the center of the polar cap. The...Solar flux variability in the *- Schumann-Runge continuum as a function of solar cycle 21. J. Geophys. Res., 85, 6063 - 6068, 1980c. Torr, M. R., P. G

  18. Mars @ ASDC

    Science.gov (United States)

    Carraro, Francesco

    "Mars @ ASDC" is a project born with the goal of using the new web technologies to assist researches involved in the study of Mars. This project employs Mars map and javascript APIs provided by Google to visualize data acquired by space missions on the planet. So far, visualization of tracks acquired by MARSIS and regions observed by VIRTIS-Rosetta has been implemented. The main reason for the creation of this kind of tool is the difficulty in handling hundreds or thousands of acquisitions, like the ones from MARSIS, and the consequent difficulty in finding observations related to a particular region. This led to the development of a tool which allows to search for acquisitions either by defining the region of interest through a set of geometrical parameters or by manually selecting the region on the map through a few mouse clicks The system allows the visualization of tracks (acquired by MARSIS) or regions (acquired by VIRTIS-Rosetta) which intersect the user defined region. MARSIS tracks can be visualized both in Mercator and polar projections while the regions observed by VIRTIS can presently be visualized only in Mercator projection. The Mercator projection is the standard map provided by Google. The polar projections are provided by NASA and have been developed to be used in combination with APIs provided by Google The whole project has been developed following the "open source" philosophy: the client-side code which handles the functioning of the web page is written in javascript; the server-side code which executes the searches for tracks or regions is written in PHP and the DB which undergoes the system is MySQL.

  19. Thermospheric circulation model in meridian plane (I)——Storm time variations in thermal status and circulation

    Institute of Scientific and Technical Information of China (English)

    萧佐; 王劲松

    2000-01-01

    A thermospheric circulation model in meridian plane (TCMMP) is introduced and a case study on the variations in night side thermosphere caused by energy deposition in auroral oval during a single magnetic substorm is expounded. Calculations show that TCMMP can correctly reflect the thermospheric thermal status and circulation patterns during storm time and the results are in agreement with previous theoretical and observational ones. This paper and other works also show the validity of TCMMP in researches on medium and large scale changes in mid- and low latitude thermosphere. Results also support strongly some related theory about the cause of ionospheric storms, expecially the negative phase storms.

  20. The effects of nitric oxide cooling and the photodissociation of molecular oxygen on the thermosphere/ionosphere system over the Argentine Islands

    Directory of Open Access Journals (Sweden)

    G. D. Wells

    Full Text Available In the past the global, fully coupled, time-dependent mathematical model of the Earth's thermosphere/ionosphere/plasmasphere (CTIP has been unable to reproduce accurately observed values of the maximum plasma frequency, foF2, at extreme geophysical locations such as the Argentine Islands during the summer solstice where the ionosphere remains in sunlight throughout the day. This is probably because the seasonal dependence of thermospheric cooling by 5.3 µm nitric oxide has been neglected and the photodissociation of O2 and heating rate calculations have been over-simplified. Now we have included an up-to-date calculation of the solar EUV and UV thermospheric heating rate, coupled with a new calculation of a diurnally varying O2 photodissociation rate, in the model. Seasonally dependent 5.3 µm nitric oxide cooling is also included. With these important improvements, it is found that model values of foF2 are in substantially better agreement with observation. The height of the F2-peak is reduced throughout the day, but remains within acceptable limits of values derived from observation, except at around 0600 h LT. We also carry out two studies of the sensitivity of the upper atmosphere to changes in the magnitude of nitric oxide cooling and photodissociation rates. We find that hmF2 increases with increased heating, whilst foF2 falls. The converse is true for an increase in the cooling rate. Similarly increasing the photodissociation rate increases both hmF2 and foF2. These changes are explained in terms of changes in the neutral temperature, composition and neutral wind.

  1. Studies of influence of energy distribution on the upper atmosphere

    Science.gov (United States)

    Sheng, Cheng

    The energy inputs into the upper atmosphere including both solar irradiation and geomagnetic energy can significantly change the upper atmosphere such as the neutral and plasma densities, velocities and temperatures. Therefore, the precise specification of the energy inputs is critical to estimate the ionosphere/thermosphere variation during both quiet and storm times. In order to improve the understanding of the energy distribution and its influence at high latitudes, specifically, we have conducted the following studies. (1) Estimation of the altitudinal distribution of Joule heating from COSMIC observations. Joule heating is the most significant way to dissipate geomagnetic energy at high latitudes. But the altitudinal distribution of Joule heating has not been studied in detail. Based on the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) observations from 2008 to 2011, the height-integrated Pedersen conductivities in both E (100-150 km) and F (150-600 km) regions and their ratio lambdaP (sumPE/sumPF) have been calculated. The result from data analysis (˜5.5) shows a smaller value than that from model (˜9), which indicates that the energy inputs into the F region may be underestimated in the model. Dependences of the ratio and the conductance in both E and F regions on the solar and geomagnetic activities have been studied as well. (2) The influence of cusp energy on the thermospheric winds has also been studied, through simulating a real event. The Global Ionosphere Thermosphere Model (GITM) has been run in different cases and under different resolutions to investigate the neutral dynamics around the cusp region. The results indicate that the heating added in the cusp causes the change of pressure gradient around the cusp and changes the neutral wind dynamics there. (3) Correlation of Poynting flux and soft particle precipitation in the dayside polar cap boundary regions has been investigated using DMSP satellite measurements

  2. Upper Endoscopy

    Medline Plus

    Full Text Available ... Procedure Brochure Understanding Upper Endoscopy Brochure Make the Best Choice for Your Endoscopic Procedure Brochure Members-only ... Procedure Brochure Understanding Upper Endoscopy Brochure Make the Best Choice for Your Endoscopic Procedure Brochure View more ...

  3. Upper Endoscopy

    Medline Plus

    Full Text Available ... Endoscopic Submucosal Dissection (ESD) Endoscopic Ultrasound (EUS) Procedures F - Z GI Bleeding Manometry Photodynamic Therapy (PDT) Polypectomy ... Gastrointestinal Glossary of Terms Home / Clinical Topics / Procedures F - Z / Upper Endoscopy (EGD) Upper Endoscopy (EGD) The ...

  4. Upper Endoscopy

    Medline Plus

    Full Text Available ... Upper Endoscopy (EGD) Upper Endoscopy (EGD) The Latest Practice Guidelines Technology Reviews Articles Videos Events & Products Ensuring the Safety of Your Endoscopic Procedure Brochure Understanding Upper Endoscopy Brochure Make the Best Choice for Your Endoscopic Procedure Brochure Members-only ...

  5. Relative Contributions of Heating and Momentum Forcing to High-Latitude Lower Thermospheric Winds

    Science.gov (United States)

    Kwak, Y. S.; Richmond, A. D.

    2015-12-01

    At high latitudes the thermospheric dynamics are gov­erned by various heat and momentum sources. Recently several modeling studies have been attempt­ed to understand the physical process that control the high-latitude lower thermospheric dynamics. Kwak and Richmond [2007] and Kwak et al. [2007] studied the momentum forcing bal­ance that are mainly responsible for maintaining the high-latitude lower thermospheric wind system by using the National Center for Atmospheric Research Thermo­sphere Ionosphere Electrodynamics General Circulation Model (NCAR TIE-GCM). Kwak and Richmond [2014] analyzed the divergence and vorticity of the high-latitude neutral wind field in the lower thermosphere during the south­ern summertime. In this study, we extend previous works by Kwak and Rich­mond [2007, 2014] and Kwak et al. [2007], which helped to better understand the physical processes maintaining thermospheric dynamics at high latitudes, and here perform a "term analysis of the potential vorticity equation" for the high-latitude neu­tral wind field in the lower thermosphere, on the basis of numerical simulations using the NCAR TIE-GCM. These analyses can provide insight into the relative strength of the heating and the momentum forcing responsible for driving rotational winds at the high-latitude lower thermosphere. The heating is the net heat including the heat transfer by downward molecular and eddy heat conduction, the absorption of solar ultraviolet (UV) and extreme ultraviolet (EUV) ra­diation, auroral heating by particles, Joule dissipation of ionospheric currents, release of chemical energy by the atomic oxygen recombination, and radiative CO2, NO and O infrared emissions. The momentum forcing is associated with the viscous force and the frictional drag force from convecting ions.

  6. Titan's Modeled Thermospheric Composition Sensitivity to Solar Cycle and Cross Section Resolution

    Science.gov (United States)

    Luspay-Kuti, A.; Mandt, K.; Greathouse, T. K.; Plessis, S.

    2015-12-01

    Saturn's largest moon, Titan has been in the spotlight of planetary research for seven decades now. This unique satellite is the only other planetary body besides the Earth to possess a substantial N2 dominated atmosphere, and stable bodies of liquids on its surface. The atmosphere and the surface are strongly coupled, and the liquids on the surface are a consequence of chemistry in the atmosphere. Titan's dense atmosphere is the site of rich organic chemistry, which begins with the photolytic destruction of the two most abundant atmospheric constituents: N2 and CH4. Photochemical modeling is an important tool in understanding the details of higher-order hydrocarbon and nitrile formation and loss at various altitudes in Titan's atmosphere, which also affect the rate of deposition onto Titan's surface. However, significant discrepancies exist among modeled (and measured) atmospheric densities of minor species, which warrant the evaluation of influencing factors in photochemical modeling. Here, we address the role of the choice of N2 photoabsorption cross-section resolution and variations in solar flux with solar cycle on the vertical profiles of various minor species in Titan's thermosphere. Special attention is placed on the changes in production and loss rates of C2H6 and HCN in response to the varying model parameters. C2H6 is the most important sink for CH4, and is a major component of the surface hydrocarbon lakes. HCN production is the first step in the incorporation of nitrogen into tholins, and is relevant to potential amino acid formation. Furthermore, HCN is the main coolant in Titan's upper atmosphere. Thus, these two minor species are particularly important in the grand scheme of Titan's coupled surface-atmosphere system.

  7. Mars Public Engagement Overview

    Science.gov (United States)

    Johnson, Christine

    2009-01-01

    This viewgraph presentation reviews the Mars public engagement goal to understand and protect our home planet, explore the Universe and search for life, and to inspire the next generation of explorers. Teacher workshops, robotics education, Mars student imaging and analysis programs, MARS Student Imaging Project (MSIP), Russian student participation, MARS museum visualization alliance, and commercialization concepts are all addressed in this project.

  8. Lagrangian Coherent Structures in a Non-Euclidean Global Thermosphere

    Science.gov (United States)

    Wang, N.; Ramirez, U.; Flores, F.; Datta-Barua, S.

    2016-12-01

    Lagrangian Coherent Structures (LCSs) are manifolds of maximum divergence or convergence in 2D or 3D time-varying flow fields. The study of LCSs has been used to predict material transport in numerous geophysical flows. The most commonly used computational method for finding LCSs is to compute the finite time Lyapunov exponent (FTLE), a scalar field measuring the ratio of stretching after a given interval of time among neighboring particles, relative to their initial separation. LCS ridges are located at the local maxima of the FTLE. The LCS must be objective (frame-invariant for different observers), and the technique for computing the FTLE that determines the LCS typically assumes a Euclidean domain. Previous work showed that LCSs are likely to exist globally at high latitudes using the Euclidean norm. Here we refine that calculation by deriving the FTLE calculation for the Riemannian manifold of a spherical surface, and applying it to the thermospheric layer of the atmosphere globally. The thermosphere is treated as a closed spherical 2D domain on which the fluid flows, assuming negligible vertical flow. The domain is discretized in longitude and latitude, and the Horizontal Wind Model 2014 (HWM14) is used to generate the 2D velocity field at each grid point, each of which is a ground speed in the local east-north-up (ENU) frame. To make the LCS objective, the ground speed in each local ENU frame is converted to angular velocity in the earth-centered earth-fixed (ECEF) coordinates. Using bilinear interpolation and including the rotational velocity of Earth to transform to an inertial frame, we trace the trajectory of each particle to compute the final positions after the integration time. Replacing the Euclidean distance between particles with the great circle distance gives the FTLE scalar field from which the LCSs can be identified. We find and illustrate objective LCSs in the neutral wind flow field at high latitudes by applying this algorithm for the

  9. Pathways of F region thermospheric mass density enhancement via soft electron precipitation

    Science.gov (United States)

    Zhang, B.; Varney, R. H.; Lotko, W.; Brambles, O. J.; Wang, W.; Lei, J.; Wiltberger, M.; Lyon, J. G.

    2015-07-01

    The efficiencies of pathways of thermospheric heating via soft electron precipitation in the dayside cusp region are investigated using the coupled magnetosphere-ionosphere-thermosphere model (CMIT). Event-based data-model comparisons show that the CMIT model is capable of reproducing the thermospheric mass density variations measured by the CHAMP satellite during both quite and active periods. During the 24 August 2005 storm event (Kp = 6-) while intense Joule heating rate occurs in the polar cusp region, including soft electron precipitation is important for accurately modeling the F region thermospheric mass density distribution near the cusp region. During the 27 July 2007 event (Kp = 2-) while little Joule heating rate occurs in the polar cusp region, the controlled CMIT simulations suggest that the direct pathway through the energy exchange between soft electrons and thermospheric neutrals is the dominant process during this event, which only has a small effect on the neutral temperature and mass density at 400 km altitude. Comparisons between the two case studies show that the indirect pathway via increasing the F region Joule heating rate is a dominant process during the 24 August 2005 storm event, which is much more efficient than the direct heating process.

  10. Variations of thermospheric composition according to AE-C data and CTIP modelling

    Directory of Open Access Journals (Sweden)

    H. Rishbeth

    2004-01-01

    Full Text Available Data from the Atmospheric Explorer C satellite, taken at middle and low latitudes in 1975-1978, are used to study latitudinal and month-by-month variations of thermospheric composition. The parameter used is the "compositional Ρ-parameter", related to the neutral atomic oxygen/molecular nitrogen concentration ratio. The midlatitude data show strong winter maxima of the atomic/molecular ratio, which account for the "seasonal anomaly" of the ionospheric F2-layer. When the AE-C data are compared with the empirical MSIS model and the computational CTIP ionosphere-thermosphere model, broadly similar features are found, but the AE-C data give a more molecular thermosphere than do the models, especially CTIP. In particular, CTIP badly overestimates the winter/summer change of composition, more so in the south than in the north. The semiannual variations at the equator and in southern latitudes, shown by CTIP and MSIS, appear more weakly in the AE-C data. Magnetic activity produces a more molecular thermosphere at high latitudes, and at mid-latitudes in summer.

    Key words. Atmospheric composition and structure (thermosphere – composition and chemistry

  11. Circulation Changes in the Mesosphere and the Lower Thermosphere Associated with Sudden Stratospheric Warmings

    Science.gov (United States)

    Hirooka, T.; Iwao, K.

    2016-12-01

    Influences of sudden stratospheric warmings (SSWs) reach the mesosphere and the thermosphere. Recently, significant global cooling during SSWs in the thermosphere have been reported on the basis of numerical simulations. However, observational studies are insufficient for the region, so that detailed 3-dimendional structure and the dynamical mechanism are still unclear. Hence, we investigate circulation changes in the mesosphere and thermosphere along with in the stratosphere during SSWs by using TIMED/SABER satellite data and radar data. The SABER observes the atmospheric temperature field in high altitudes up to the lower thermosphere (ca. 120km). Time series of the SABER data includes tidal components, because the satellite orbit is not sun-synchronous and the local time of observation gradually decreases at a specific latitude. The perfect separation of the time series data into tidal and daily changes is difficult especially when diurnal components are amplified. Therefore, we additionally analyze the radar data at some selected stations. Resultantly, north polar temperatures during SSWs show lower thermosphere warming and mesospheric cooling along with the anti-correlated temperature changes in the wide region except over the north pole. In the presentation, we discuss further detailed features of circulation changes associated with SSWs.

  12. Optical interferometric studies of the nighttime equatorial thermosphere: Enhanced temperatures and zonal wind gradients

    Science.gov (United States)

    Meriwether, J. W.; Biondi, M. A.; Herrero, F. A.; Fesen, C. G.; Hallenback, D. C.

    1997-09-01

    Fabry-Perot interferometric observations at 630 nm of equatorial thermospheric winds and temperatures in the four cardinal directions and zenith from Arequipa, Peru, during local winter for moderate and high solar fluxes showed elevated temperatures over the Andes Mountains that persisted through the night. The difference in temperature between east and west observations was typically ~100 to 200 K for moderate flux values and as high as 400 K at solar maximum. Correlated with these localized heating regions were differences in the zonal thermospheric wind of 50 to 70 m/s for observations to the west and to the east of the Arequipa observatory. Also noted in these periods for the region over the Andes was the increased variance of the temperature values above the measurement error. These effects of increased variability and localized heating were not observed at solar minimum. The lack of a significant local time dependence in the diurnal variation of the temperature enhancements suggests that the origin of the heating cannot be related to the coupling of the electrodynamics of the ionosphere to the thermosphere. Instead the hypothesis is advanced that gravity wave energy from the surface penetrates into the thermosphere, where viscous dissipation causes the heating. Such wave activity would also explain the increased variability of the temperatures for the thermosphere regions over mountainous terrain.

  13. Thermospheric mass density measurement from precise orbit ephemeris

    Directory of Open Access Journals (Sweden)

    Junyu Chen

    2016-05-01

    Full Text Available Atmospheric drag, which can be inferred from orbit information of low-Earth orbiting (LEO satellites, provides a direct means of measuring mass density. The temporal resolution of derived mass density could be in the range from minutes to days, depending on the precision of the satellite orbit data. This paper presents two methods potentially being able to estimate thermosphere mass density from precise obit ephemeris with high temporal resolution. One method is based on the drag perturbation equation of the semi-major axis and the temporal resolution of retrieved density could be 150 s for CHAMP satellite. Another method generates corrections to densities computed from a baseline density model through a Kalman filter orbit drag coefficient determination (KFOD process and the temporal resolution of derived density could be as high as 30 s for CHAMP satellite. The densities estimated from these two methods are compared with densities obtained from accelerometer data of CHAMP satellite. When the accelerometer data based densities are used as reference values, the mean relative accuracy of the densities derived from precision orbit data using the two methods is within approximately 10%. An application of the derived densities shows that the derived densities can reduce orbit predication errors.

  14. Silicon chemistry in the mesosphere and lower thermosphere

    Science.gov (United States)

    Gómez‐Martín, Juan Carlos; Feng, Wuhu; Janches, Diego

    2016-01-01

    Abstract Silicon is one of the most abundant elements in cosmic dust, and meteoric ablation injects a significant amount of Si into the atmosphere above 80 km. In this study, a new model for silicon chemistry in the mesosphere/lower thermosphere is described, based on recent laboratory kinetic studies of Si, SiO, SiO2, and Si+. Electronic structure calculations and statistical rate theory are used to show that the likely fate of SiO2 is a two‐step hydration to silicic acid (Si(OH)4), which then polymerizes with metal oxides and hydroxides to form meteoric smoke particles. This chemistry is then incorporated into a whole atmosphere chemistry‐climate model. The vertical profiles of Si+ and the Si+/Fe+ ratio are shown to be in good agreement with rocket‐borne mass spectrometric measurements between 90 and 110 km. Si+ has consistently been observed to be the major meteoric ion around 110 km; this implies that the relative injection rate of Si from meteoric ablation, compared to metals such as Fe and Mg, is significantly larger than expected based on their relative chondritic abundances. Finally, the global abundances of SiO and Si(OH)4 show clear evidence of the seasonal meteoric input function, which is much less pronounced in the case of other meteoric species. PMID:27668138

  15. Thermospheric mass density measurement from precise orbit ephemeris

    Institute of Scientific and Technical Information of China (English)

    Junyu Chen; Jizhang Sang

    2016-01-01

    Atmospheric drag,which can be inferred from orbit information of low-Earth orbiting (LEO)satellites,provides a direct means of measuring mass density.The temporal resolution of derived mass density could be in the range from minutes to days,depending on the precision of the satellite orbit data.This paper presents two methods potentially being able to estimate thermosphere mass density from precise obit ephemeris with high temporal resolution.One method is based on the drag perturbation equation of the semi-major axis and the temporal resolution of retrieved density could be 150 s for CHAMP satellite.Another method generates corrections to densities computed from a baseline density model through a Kalman filter orbit drag coefficient determination (KFOD) process and the temporal resolution of derived density could be as high as 30 s for CHAMP satellite.The densities estimated from these two methods are compared with densities obtained from accelerometer data of CHAMP satellite.When the accelerometer data based densities are used as reference values,the mean relative accuracy of the densities derived from precision orbit data using the two methods is within approximately 10%.An application of the derived densities shows that the derived densities can reduce orbit predication errors.

  16. Remote Sensing of lower thermospheric temperature and composition based on observations of O2 Atmospheric band emission.

    Science.gov (United States)

    Christensen, A. B.; Yee, J.; Budzien, S. A.; Bishop, R. L.; Hecht, J. H.; Stephan, A. W.; Crowley, G.

    2011-12-01

    The properties of the O2 Atmospheric bands emitted in the lower thermosphere are examined through the use of a photochemical model and compared with measurements from the RAIDS near-infrared spectrometer on the International Space Station. An updated model (Yee, 2011) has been used to establish the sensitivity of the line-of-sight (LOS) brightness of the (0,0), (1,1) and (0,1) bands to changes in neutral composition and some reaction rate and branching ratios. We found that the most sensitive region to O2 variability is near 120 km where the brightness is ~ [O2]^2. Calculations based on the MSIS-90E neutral atmospheric model corresponding to the geographical locations of the brightness measurements at 120 and 125 km for several days of observations indicate greater variability in the model results than observed by RAIDS based on our current understanding of the pointing errors. Up to about 200 km the (0,0) band lifetime is sufficiently long to allow thermalization of the upper state through collisions with the background gasses making the rotational distribution representative of the local temperature. The analysis of rocket data by Heller et al. (1991) and more recently Sheese et al. (2010) using OSIRIS observations up to an altitude of ~ 110 km illustrates the approach. Using the same measurement concept, the RAIDS data extend the range of altitudes an additional two scale heights to approximately 130 km. Comparing RAIDS and TIMED/SABER LOS measurements we have been able to validate temperatures in the region around 100 km. During moderate geomagnetic activity (Kp ~ 4) localized but greatly enhanced temperatures have been observed. J. W. Heller, A. B. Christensen, J. H. Yee and W. E. Sharp, Mesospheric temperature inferred from daytime observation of the O2 atmospheric (0,0) band system, J. Geophys. Res., 96,19,499-19,505,1991. P. E. Sheese, E. J. Llewellyn, R. L. Gattinger, A. E. Bourassa, D. A. Degenstein, N. D. Lloyd, and I. C. McDade, Temperatures in the

  17. Upper Endoscopy

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    Full Text Available ... Upper Endoscopy (EGD) Quality & Safety GIQuIC Registry Infection Control Privileging & Credentialing Quality Indicators Education & Meetings Advanced Education & Training ARIA Industry ...

  18. The responses of the thermosphere due to a geomagnetic storm: A MHD model

    Science.gov (United States)

    Wu, S. T.; Chang, S.

    1972-01-01

    A magnetohydrodynamics theory was used to study the dynamic response of the neutral atmosphere to a geomagnetic storm. A full set of magnetohydrodynamic equations appropriate for the present problem is derived and their various orders of approximation are discussed in some detail. In order to demonstrate the usefulness of this theoretical model, the May 1967 geomagnetic storm data were used in the resulting set of nonlinear, time dependent, partial differential magnetohydrodynamic equations to calculate variations of the thermosphere due to the storm. The numerical results are presented for wind speeds, electric field strength, and amount of joule heating at a constant altitude for the data recorded. Data show that the strongest thermospheric responses are at the polar region becoming weaker in the equatorial region. This may lead to the speculation that a thermospheric wave is generated in the polar region due to the geomagnetic storm which propagates towards the equator.

  19. Winds and composition changes in the thermosphere using the transfer function model

    Science.gov (United States)

    Mayr, H. G.; Harris, I.; Herrero, F. A.; Varosi, F.

    1997-04-01

    Different theoretical formulations are used to describe the thermosphere, ranging from fully analytical, linear models based, in the case of gravity waves, on the work of C. O. Hines, to fully numerical, thermospheric general circulation models (TGCMs), which account for non-linear processes and coupling with the ionospheric plasma. The semi-analytical Transfer Function Model (TFM) describes perturbations in the wind field, temperature and composition, accounting in self-consistent form for the momentum transfer between species. The perturbations are driven by external energy and momentum sources associated with absorbed solar radiation and magnetospheric processes. Compared with TGCMs, the TFM is simplified mainly by its linear approximation. But the model is not limited in its spatial and temporal resolutions, and it describes acoustic gravity waves that are generated in the thermosphere and partially propagate through the lower atmosphere. Moreover, the model is semi-analytical, which helps in delineating and understanding the dynamical characteristics. Using expansions in terms of vector spherical harmonics and Fourier transformation, the transfer function of the atmosphere is obtained through numerical height integration, which is time consuming computationally but needs to be done only once. Once the transfer function is constructed, the thermospheric response is obtained virtually instantaneously, thus providing an efficient tool for numerical simulation and experimentation. After a review of the TFM, results are discussed, which describe a number of thermospheric phenomena covering a wide range of spatial and temporal scales. These include magnetic storm effects as well as gravity waves propagating in the thermosphere, which are partially reflected from the Earth's surface and ducted through the lower atmosphere.

  20. Carbon Dioxide Trends in the Lower and Upper Atmosphere

    Science.gov (United States)

    Qian, L.

    2016-12-01

    Carbon dioxide (CO2) is increasing throughout the atmosphere, but recent observations indicate that it is increasing faster near and above the mesopause than in the lower and middle atmosphere. Currently model simulations do not reproduce this differential CO2 trend, and the mechanism behind it is unknown. We examine CO2 trends in the lower and upper atmosphere using a combination of model simulations and data analysis with CO2 observed by ACE-FTS onboard the SCISAT-1 satellite and SABER onboard the NASA TIMED satellite, to understand this differential trend and find out whether it is responsible for the observed changes in thermosphere and ionosphere climate.

  1. The microwave limb sounder for the Upper Atmosphere Research Satellite

    Science.gov (United States)

    Waters, J. W.; Peckham, G. E.; Suttie, R. A.; Curtis, P. D.; Maddison, B. J.; Harwood, R. S.

    1988-01-01

    The Microwave Limb Sounder was designed to map the concentrations of trace gases from the stratosphere to the lower thermosphere, to improve understanding of the photochemical reactions which take place in this part of the atmosphere. The instrument will measure the intensity of thermal radiation from molecules in the atmosphere at frequencies corresponding to rotational absorption bands of chlorine monoxide, ozone, and water vapor. Molecular concentration profiles will be determined over a height range of 15 to 80 km (20 to 45 km for C10). The 57 deg inclination orbit proposed for the Upper Atmosphere Research Satellite will allow global coverage.

  2. Tracking the energy input form the magnetosphere to the ionosphere-thermosphere system

    Science.gov (United States)

    Zesta, E.; Connor, H.; Shi, Y.; Raeder, J.; Fedrizzi, M.; Fuller-Rowell, T. J.; Codrescu, M.

    2014-12-01

    During geomagnetically active times, the ionosphere - thermosphere (IT) system is strongly affected by magnetospheric energy that comes in the form of auroral particle precipitation and Poynting flux. This ultimately results in the increase of the thermospheric mass density, a critical parameter not only for determining and predicting air drag on satellites, but also for understanding the solar wind - magnetosphere- IT coupling. We use observations and model simulations to explore when, where and how energy transfers from the solar wind through the magnetosphere and is deposited into the IT system during solar wind disturbances. We observe and simulate dynamic pressure impacts on the magnetosphere and a magnetic storm main phase. We use thermospheric density observations from the CHAMP and GRACE satellites and Poynting flux measurements from Defense Meteorological Satellite Platform (DMSP) satellites. We show that the thermosphere density as well as the downward Poynting flux intensified shortly after (within ~20 min) the sudden enhancement of the solar wind dynamic pressure mostly in the dayside auroral zone and polar cap regions with the peaks in the vicinity of the cusp. Simulations from the two-way coupled OpenGGCM-CTIM magnetosphere-ionosphere-thermosphere model show that the ionospheric Joule heating also increases abruptly along with the sudden enhancement of the dynamic pressure in the same regions. The modeling results show that the pair of high-latitude localized cusp field-aligned currents (FACs) are intensified and extended azimuthally as a result of the enhanced dayside high-latitude reconnection caused by the sudden increase of the solar wind dynamic pressure. They are likely the source of the enhanced Joule heating and the ensuing thermospheric heating in that region. We also look at the first hours of a magnetic storm main phase where the picture is significantly more complex, but Poynting flux and thermospheric density first enhance at polar

  3. First simultaneous measurements of thermospheric winds and zonal ion drifts from the Jicamarca Radio Observatory

    Science.gov (United States)

    Meriwether, John; Baker, Brooke; Twork, Greg; Chau, Jorge; Veliz, Oskar; Woodman, Ronald; Hedden, Russell; Hysell, David

    The first simultaneous observations of thermospheric winds and zonal ion drifts have been ob-tained at the Jicamarca Radio Observatory using a new Fabry-Perot interferometer observatory installed on a mountain ridge overlooking the valley where the JRO radar is located. The re-sults show that the neutral winds and ion drifts generally have the same speed and temporal variation characteristics. These results illustrate the simultaneous detection of the midnight temperature maximum as well. The paper will also describe efforts to obtain common volume measurements of thermospheric winds and temperatures utilizing the FPI Arequipa observatory which is located 4 degrees south of the geomagnetic equator.

  4. Measurements of Mesosphere and Lower Thermosphere Winds by the TIMED Doppler Interferometer

    Science.gov (United States)

    Killeen, T. L.; Gablehouse, R. D.; Johnson, R. M.; Wu, Q.; Solomon, S. C.; Gell, D. A.; Niciejewski, R. J.; Skinner, W. R.; Kafkalidis, J. F.; Ortland, D. A.

    2002-12-01

    Since the launch of the NASA Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite in December 2001, the TIMED Doppler Interferometer (TIDI) has been measuring the global wind field in the mesosphere and lower thermosphere. Validation of these data using ground-based and other space-based observations is in progress. Early analyses have focused on wind measurements in the 60 to 110 km altitude region using emissions from the O2 Atmospheric (0-0) band. We will present results showing the variability of tidal oscillations in the middle atmosphere, and new measurements of polar mesopause dynamics.

  5. Auroral ionospheric and thermospheric measurements using the incoherent scatter technique

    Energy Technology Data Exchange (ETDEWEB)

    Kofman, W. (CEPHAG, St. Martin (France))

    1992-11-01

    The incoherent scatter technique has been applied since 1965 to study the ionosphere and thermosphere in different regions of the Earth. The analysis of the received signal gives access to several ionospheric parameters as a function of height: electron density, electron and ion temperatures and ion velocity. The derivation of these parameters is usually a complicated mathematical procedure that requires a non-linear regression program. A lot of research has been done in the ionospheric and atmospheric science using this technique. In this paper we describe how one derives the ion-neutral collision frequency and the ion composition parameters. It is usually difficult to retrieve these parameters with the incoherent scatter technique; as a result, in the standard data analysis procedure, an ionospheric model is used instead. However the numerical values chosen in the model have an influence on the other derived parameters. For instance the choice of a wrong ion composition leads to erroneous plasma temperatures. It is therefore important to assess by how much the standard procedure deviates from reality. For this reason we compare the ion composition and collision frequency retrieved from a sophisticated analysis scheme with the values that are derived from models under similar geophysical conditions. It is also possible to derive from the observed ionospheric parameters the neutral concentrations, temperatures and winds, by using the energy and momentum equations for the ions and the neutrals. In this paper the different methods and the corresponding assumptions involved in the data analysis are discussed. We describe the influence of the frictional heating, of the vertical neutral wind and of the ionospheric perturbations on the derivation of the neutral atmospheric parameters. Our discussion of the processes involved are drawn from results obtained by Chatanika, Sondrestrom and EISCAT radars.

  6. Longitudinal and geomagnetic activity modulation of the equatorial thermosphere anomaly

    Science.gov (United States)

    Lei, Jiuhou; Thayer, Jeffrey P.; Forbes, Jeffrey M.

    2010-08-01

    In this paper we examine the detailed similarities and differences between the equatorial thermosphere anomaly (ETA) and the equatorial ionization anomaly (EIA) from 20 March to 6 April 2002, when both the ETA and the EIA are distinct in the Challenging Minisatellite Payload (CHAMP) observations. The characteristics of the ETA and the EIA are obtained from the CHAMP accelerometer, in situ electron density measurements, and total electron content (TEC) above the CHAMP satellite. Our results show that the trough locations of the ETA and the EIA in latitude show a good agreement, and both correspond well with the dip magnetic equator, while the ETA crests are usually located poleward of the EIA. Meanwhile, the latitudinal locations of the ETA crests exhibit strong hemispheric asymmetry and large variability during our study interval. The longitudinal variations between the EIA and the ETA show significant differences. The EIA crests from the CHAMP observations show strong wave 4 structures, but the primary component in the ETA is wave 1. Moreover, the ETA densities show strong variations in response to geomagnetic activity, whereas CHAMP in situ electron densities and TEC at the EIA do not reflect such large day-to-day variability. Therefore, a simple EIA-ETA relationship cannot explain the dependence of the longitudinal and geomagnetic activity modulation of the ETA and the EIA. The meridional ion drag, which is significantly modulated by enhanced equatorward winds during elevated geomagnetic activity, is probably responsible for some of the observed features in the ETA, although no unambiguous explanation for ETA formation yet exists.

  7. Mean vertical wind in the mesosphere-lower thermosphere region (80–120 km deduced from the WINDII observations on board UARS

    Directory of Open Access Journals (Sweden)

    V. Fauliot

    Full Text Available The WINDII interferometer placed on board the Upper Atmosphere Research Satellite measures temperature and wind from the O(1S green-line emission in the Earth's mesosphere and lower thermosphere. It is a remote-sensing instrument providing the horizontal wind components. In this study, the vertical winds are derived using the continuity equation. Mean wind annually averaged at equinoxes and solstices is shown. Ascendance and subsidence to the order of 1–2 cm s–1 present a seasonal occurrence at the equator and tropics. Zonal Coriolis acceleration and adiabatic heating and cooling rate associated to the mean meridional and vertical circulations are evaluated. The line emission rate measured together with the horizontal wind shows structures in altitude and latitude correlated with the meridional and vertical wind patterns. The effect of wind advection is discussed.

  8. Rotorcrafts for Mars Exploration

    Science.gov (United States)

    Balaram, J.; Tokumaru, P. T.

    2014-06-01

    Rotorcraft mobility provides a number of useful capabilities to potential Mars missions. We present some recent results relating to the design and test of Mars rotorcraft mobility elements, and aspects of rotorcraft system and mission design.

  9. Mars Gashopper Airplane Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Mars Gas Hopper Airplane, or "gashopper" is a novel concept for propulsion of a robust Mars flight and surface exploration vehicle that utilizes indigenous CO2...

  10. Determining global ionospheric conductivity in the satellite and data assimilation age and assessing its influence on the Magnetosphere-Ionosphere-Thermosphere system

    Science.gov (United States)

    McGranaghan, R. M.

    This work focuses on determining how effectively the upper atmosphere, as a medium, transmits the influence of an electric field into differential charge motion (current). This effect is called conductivity. Conductivity modulates height-specific energy deposition in the ionosphere and thermosphere, and is therefore critical to the study of the Earth space environment. The key to the improvements presented in this dissertation is a complex systems approach through which cutting-edge mathematical tools and computational techniques are utilized to improve modeling and understanding of conductivity. These improvements replace limiting assumptions in conductivity modeling (Maxwellian particle energy distribution and thin-shell conductance approximation) that have existed for nearly three decades. My new computational methods permit the first global height-specific views of how solar and magnetospheric energy influence the dynamics of the ionosphere and thermosphere. This dissertation promotes much more effective and efficient use of under-used geospace observations in data assimilation and forecasting. The outcome is significantly improved conductance and conductivity modeling capabilities that underpin a system science approach to understanding geospace interactions at smaller scales and higher resolution. This work has four facets, each addressing a limitation in the current state of conductivity modeling: 1) characterization of high-latitude particle precipitation and its combination with the effects of solar ionization; 2) creation of the conductivity model; 3) identification of the characteristic features of the ionospheric conductivity and capturing these features in a covariance model; and 4) creation of a means to estimate the dynamic global distribution of conductivity via optimal interpolation. The next step, which is explored in this dissertation, is three-dimensional, global estimation of conductivity. The engineering application of this work is in the

  11. Global and Seasonal Extent of the Thermospheric Midnight Temperature Maximum as Seen in O(1D) Nightglow by WINDII and Simulated by C-IAM

    Science.gov (United States)

    Shepherd, M. G.

    2014-12-01

    Manifestations of thermospheric dynamics are observed in the variations of upper atmosphere neutral winds, temperature, density and F-region plasma over a wide time range. These fields are influenced by perturbations propagating vertically from the lower and middle atmosphere (e.g. tides) and from above through variations in the solar and geomagnetic activity. The midnight temperature maximum (MTM) is a large scale neutral temperature anomaly with wide spread influence on the low-latitude thermosphere and ionosphere. Variations in the low latitudes' nighttime neutral density, termed midnight density maximum (MDM) have also been observed and modeled. Although there is a large body of work on the characteristics of the MTM (& MDM) there are still a few questions which remain to be answered concerning the global scale distribution of the MTM (&MDM), their spatial extent and longitudinal variations, their global seasonal occurrence pattern and amplitude. The Wind Imaging Interferometer (WINDII) flown on the Upper Atmosphere Research Satellite (UARS) provides among other parameters multiyear observations of O(1D) nightglow volume emission rates (VER), Doppler temperatures, and neutral winds over the altitude range from 150 to 300 km with continuous latitude coverage from 42°N to 42°S and to 72° in one hemisphere every 36 days. These correlative in time and space data are employed in the study of the global and seasonal extent of the MTM/MDM. The results are compared with simulations by the Canadian Ionosphere and Atmosphere Model (C-IAM). Reasonable agreement is obtained in terms of temporal, solar flux, and solar zenith angle variations.

  12. Phoenix Deepens Trenches on Mars

    Science.gov (United States)

    2008-01-01

    The Surface Stereo Imager on NASA's Phoenix Mars Lander took this false color image on Oct. 21, 2008, during the 145th Martian day, or sol, since landing. The bluish-white areas seen in these trenches are part of an ice layer beneath the soil. The trench on the upper left, called 'Dodo-Goldilocks,' is about 38 centimeters (15 inches) long and 4 centimeters (1.5 inches) deep. The trench on the right, called 'Upper Cupboard,' is about 60 centimeters (24 inches) long and 3 centimeters (1 inch) deep. The trench in the lower middle is called 'Stone Soup.' The Phoenix mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  13. Upper Endoscopy

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    Full Text Available ... Upper Endoscopy (EGD) The Latest Practice Guidelines Technology Reviews Articles Videos Events & Products Ensuring the Safety of ... S0016-5107(98)70268-8 View more Technology Reviews Members-only content Document Link: ASGE Leading Edge: ...

  14. Upper Endoscopy

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    Full Text Available ... Upper Endoscopy (EGD) The Latest Practice Guidelines Technology Reviews Articles Videos Events & Products Ensuring the Safety of ... S0016-5107(98)70268-8 View more Technology Reviews Members-only content Document Link: ASGE Leading Edge: ...

  15. Upper Endoscopy

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    Full Text Available ... EGD) Upper Endoscopy (EGD) The Latest Practice Guidelines Technology Reviews Articles Videos Events & Products Ensuring the Safety ... 1016/S0016-5107(98)70268-8 View more Technology Reviews Members-only content Document Link: ASGE Leading ...

  16. Upper Endoscopy

    Medline Plus

    Full Text Available ... EGD) Upper Endoscopy (EGD) The Latest Practice Guidelines Technology Reviews Articles Videos Events & Products Ensuring the Safety ... 1016/S0016-5107(98)70268-8 View more Technology Reviews Members-only content Document Link: ASGE Leading ...

  17. Upper Endoscopy

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    Full Text Available ... Staff Rent IT&T Facility Gastrointestinal Glossary of Terms Home / Clinical Topics / Procedures F - Z / Upper Endoscopy ( ... Facebook ASGE on Youtube ASGE on Twitter Privacy | Terms of Use | © 2017 American Society for Gastrointestinal Endoscopy

  18. The effect of H3+ cooling on jovian thermospheric energy and momentum balance

    Science.gov (United States)

    Ray, L. C.; Achilleos, N. A.; Miller, S.

    2014-12-01

    When the Galileo probe entered Jupiter's equatorial atmosphere, it measured thermospheric exobase temperatures of ~900 K, 700 K higher than what was expected from solar EUV heating. Therefore, there is an 'energy crisis' at Jupiter, in which a large source of equatorial heating is unaccounted for. A prime candidate to explain the high temperatures is the transport of auroral energy equatorwards from high latitudes. However, the combination of strong Coriolis forces from the rapid planetary rotation rate, coupled with ion drag from magnetosphere-ionosphere coupling, results in an 'ion drag fridge' effect (Smith et al., 2007), which acts to transport auroral energy poleward, rather than equatorward. We modify the UCL JASMIN model (Jovian Axisymmetric Simulator with Magnetosphere, Ionosphere, and Neutrals) to include the effects of auroral heating and H3+ cooling. Thus far, auroral heating and H3+ cooling were neglected in dynamical models of the coupled thermosphere-ionosphere-magnetosphere system, in order to focus on the effects of joule heating and ion drag on the jovian thermosphere. We explore how including these heating and cooling terms alters the energy and momentum balance, and subsequently meridional transport through Jupiter's thermosphere.

  19. Terrestrial thermospheric storm effects during the first weeks of the Dynamics Explorer 1 mission

    Science.gov (United States)

    Immel, T. J.; Crowley, G.; Craven, J. D.

    2004-05-01

    Global far-ultraviolet (FUV) images of Earth provide an unparalleled view of the development of thermospheric storms during periods of enhanced magnetic activity. More than 20 years ago, the Spin Scan Imager onboard the Dynamics Explorer 1 satellite obtained the first global images of the development of thermospheric perturbations caused by enhanced auroral activity. This capability comes from the FUV component of the imager, that by measuring the bright OI 130.4-nm triplet originating in the thermosphere can monitor variations in the relative thermospheric column abundances of O and N2. Short-term variations in the ratio of these parameters usually indicate the recent occurrence of high-latitude Joule heating. The first several weeks of operation of the instrument (beginning in September, 1981) were marked by a particularly interesting series of magnetic substorm and storm events which all had an effect, to varying degrees, on the OI FUV dayglow brightness. In this study the O/N2 variations are simulated for the entire period using the NCAR TIMEGCM in order to identify the causative factors in the development of O/N2 depletions. This period was also marked by good measurements of the solar wind speed, density, and embedded magnetic field from the ISEE-3 satellite. These are important inputs for the TIMEGCM. Particular attention is paid to the sense of IMF By, which has a strong effect on the magnitude and local time of the peak in the high latitude neutral circulation speed.

  20. Substorm-related thermospheric density and wind disturbances derived from CHAMP observations

    Directory of Open Access Journals (Sweden)

    P. Ritter

    2010-06-01

    Full Text Available The input of energy and momentum from the magnetosphere is most efficiently coupled into the high latitude ionosphere-thermosphere. The phenomenon we are focusing on here is the magnetospheric substorm. This paper presents substorm related observations of the thermosphere derived from the CHAMP satellite. With its sensitive accelerometer the satellite can measure the air density and zonal winds. Based on a large number of substorm events the average high and low latitude thermospheric response to substorm onsets was deduced. During magnetic substorms the thermospheric density is enhanced first at high latitudes. Then the disturbance travels at an average speed of 650 m/s to lower latitudes, and 3–4 h later the bulge reaches the equator on the night side. Under the influence of the Coriolis force the travelling atmospheric disturbance (TAD is deflected westward. In accordance with present-day atmospheric models the disturbance zonal wind velocities during substorms are close to zero near the equator before midnight and attain moderate westward velocities after midnight. In general, the wind system is only weakly perturbed (Δvy<20 m/s by substorms.

  1. Estimating Ionosphere-Thermosphere Energy Budget: the ICME Storm of 16-19 March 2013

    Science.gov (United States)

    Verkhoglyadova, O. P.; Meng, X.; Mannucci, A. J.; Mlynczak, M. G.; Hunt, L. A.; Lu, G.

    2016-12-01

    The ionosphere-thermosphere (IT) energy budget for the ICME storm of 16-19 March 2013 is estimated with the Global Ionosphere-Thermosphere Model (GITM), empirical models and observation-derived proxies. GITM is used to analyze the IT energy partitioning in detail, with a focus on auroral heating, Joule heating and thermospheric cooling. Solar wind data, F10.7, OVATION Prime and the Weimer 2005 model are used to drive GITM from above. Thermospheric nitric oxide and carbon dioxide cooling emission powers and fluxes are estimated from TIMED/SABER measurements. AMIE estimations of hemispheric power and Joule heating are presented, based on data from global magnetometers, the AMPERE magnetic field data, SSUSI auroral images and the SuperDARN radar network. Additionally, we inter-compare selected energy channels for five CME-type and eight HSS-type storms modeled with GITM and TIEGCM. We discuss challenges and discrepancies in estimating and modeling the IT energy budget, especially Joule heating, during geomagnetic storms.

  2. Global effect of auroral particle and Joule heating in the undisturbed thermosphere

    Science.gov (United States)

    Hinton, B. B.

    1978-01-01

    From the compositional variations observed with the neutral atmosphere composition experiment on OGO 6 and a simplified model of thermospheric dynamics, global average values of non-EUV heating are deduced. These are 0.19-0.25 mW/sq m for quiet days and 0.44-0.58 mW/sq m for ordinary days.

  3. Atomic oxygen distributions in the Venus thermosphere: Comparisons between Venus Express observations and global model simulations

    Science.gov (United States)

    Brecht, A. S.; Bougher, S. W.; Gérard, J.-C.; Soret, L.

    2012-02-01

    Nightglow emissions provide insight into the global thermospheric circulation, specifically in the transition region (˜70-120 km). The O 2 IR nightglow statistical map created from Venus Express (VEx) Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS) observations has been used to deduce a three-dimensional atomic oxygen density map. In this study, the National Center of Atmospheric Research (NCAR) Venus Thermospheric General Circulation Model (VTGCM) is utilized to provide a self-consistent global view of the atomic oxygen density distribution. More specifically, the VTGCM reproduces a 2D nightside atomic oxygen density map and vertical profiles across the nightside, which are compared to the VEx atomic oxygen density map. Both the simulated map and vertical profiles are in close agreement with VEx observations within a ˜30° contour of the anti-solar point. The quality of agreement decreases past ˜30°. This discrepancy implies the employment of Rayleigh friction within the VTGCM may be an over-simplification for representing wave drag effects on the local time variation of global winds. Nevertheless, the simulated atomic oxygen vertical profiles are comparable with the VEx profiles above 90 km, which is consistent with similar O 2 ( 1Δ) IR nightglow intensities. The VTGCM simulations demonstrate the importance of low altitude trace species as a loss for atomic oxygen below 95 km. The agreement between simulations and observations provides confidence in the validity of the simulated mean global thermospheric circulation pattern in the lower thermosphere.

  4. Solar and chemical reaction-induced heating in the terrestrial mesosphere and lower thermosphere

    Science.gov (United States)

    Mlynczak, Martin G.

    1992-01-01

    Airglow and chemical processes in the terrestrial mesosphere and lower thermosphere are reviewed, and initial parameterizations of the processes applicable to multidimensional models are presented. The basic processes by which absorbed solar energy participates in middle atmosphere energetics for absorption events in which photolysis occurs are illustrated. An approach that permits the heating processes to be incorporated in numerical models is presented.

  5. Improved short-term variability in the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model

    NARCIS (Netherlands)

    Häusler, K.; Hagan, M.E.; Baumgaertner, A.J.G.; Maute, A.; Lu, G.; Doornbos, E.N.; Bruinsma, S.; Forbes, J.M.; Gasperini, F.

    2014-01-01

    We report on a new source of tidal variability in the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). Lower boundary forcing of the TIME-GCM for a simulation of November–December 2009 based on 3-hourly Modern-Era Retro

  6. Thermospheric Gravity Wave Activity near Summer Solstice 2014 Based on Analysis of Tromsø Dynasonde Data

    Science.gov (United States)

    Zabotin, Nikolay; Negrea, Catalin; Godin, Oleg A.; Rietveld, Michael; Bullett, Terence; Zabotina, Liudmila

    2015-04-01

    Propagation conditions for thermospheric gravity waves in the Polar Regions are characterized by combination of several unique factors including interactions with the Auroral activity and the polar vortex. Tropospheric sources of the acoustic gravity waves (AGWs), such as wind disturbances caused by mountain relief, are likely to be complemented by energy and momentum depositions associated with fluxes of energetic particles from above. We apply recently developed Dynasonde techniques to study peculiarities of the gravity wave characteristics over Northern Scandinavia. A week-long (adjacent to the summer 2014 Solstice) data series for this study has been obtained with the Dynasonde system at the EISCAT's Tromsø Observatory operating continuously with sounding session periodicity equal to 2 min. A component of Dynasonde data analysis software, the inversion procedure NeXtYZ, has been used to attribute plasma density, plasma contour tilts, and line-of-sight Doppler values to the altitudes in real space with 1 km resolution. The temporal and spatial resolution allows visualization of the phase fronts of the traveling ionospheric disturbances (TIDs) and measuring the full set of parameters (both vertical and horizontal) of TID activity in the upper atmosphere between the base of the E layer and the maximum of F layer, where the ionospheric plasma can reflect the radar's signal. We verify the nature of the activity for selected spectral peaks by substituting the TID parameters into the dispersion relation describing acoustic-gravity waves. Application of the Lomb-Scargle periodogram technique to the tilt data provides useful insight into the dynamics of spectral composition of the TIDs, which we compare to results of a similar analysis obtained for mid-latitude (Wallops Island, VA) Dynasonde location. Interference of wave packets and multi-path propagation are more frequent in polar thermosphere compared to mid-latitude situation. Backtracking of selected waves to

  7. Earth’s Interaction Region: Plasma-Neutral Interactions in the Weakly Ionized gas of Earth’s High Latitude Upper Atmosphere

    Science.gov (United States)

    Thayer, Jeffrey; Hsu, Vicki

    2015-04-01

    The high-latitude regions of Earth’s upper atmosphere are strongly influenced by plasma-neutral interactions. These interactions couple electrodynamic processes of the ionosphere with hydrodynamic processes of the more abundant thermosphere neutral gas, consequently connecting the high-latitude upper atmosphere to distant regions of the geoplasma environment. This produces a complex spatial and temporal interplay of competing processes that results in a myriad of physical and chemical responses and a rich array of neutral and plasma morphologies that constitute the high-latitude thermosphere and ionosphere. The altitude extent from the lower thermosphere to the upper ionosphere (90km - 1000km) can be considered Earth’s space-atmosphere interaction region - likened to the solar chromosphere’s interaction region where radiative processes and hydrodynamic waves from the dense lower atmosphere produce a cold lower boundary that quickly transitions over a few 100 kilometers to neutral and plasma temperatures that are five times hotter. A thousand or more kilometers further in altitude, Earth's upper atmosphere becomes a hot, collisionless, geomagnetically controlled protonosphere whose neutral and plasma population originates from the thermosphere and ionosphere. A grand challenge in the study of Earth’s interaction region is how the collision-dominated thermosphere/ionosphere system exchanges energy, mass and momentum with the collisionless magnetosphere. This talk will focus primarily on collision-dominated processes of the high-latitude ionosphere and the electromagnetic energy transfer processes that lead to frictional heating of ions and neutrals, and plasma instability phenomenon that leads to extreme electron heating. Observations of the ionosphere response to these processes will be illustrated using incoherent scatter radar measurements. Relevance to the solar chromosphere will be identified where appropriate and outstanding issues in Earth

  8. Meteor Trails in the Lower Thermosphere: What Do Large Radars Really Detect?

    Science.gov (United States)

    Oppenheim, M. M.; Dimant, Y. S.

    2014-12-01

    Tens of millions of detectable meteors ablate in the Earth's upper atmosphere each second, creating turbulent plasma trails that persist for up to minutes as they dissipate into the background ionosphere. These trails produce easily detected radar signals with a wealth of information. This talk will present a detailed analysis of two aspects of meteor physics: (1) the early evolution of meteors as they first ionize and create radar reflections called head echoes, and (2) the later evolution as meteor plasmas develop turbulence and create radar signals called non-specular or range spread meteor trail echoes. Head echoes form when sublimated material from a meteoroid initially collides with atmospheric molecules and ionize. Kinetic theory shows that this plasma develops over a length-scale close to the ion mean-free-path but with a highly non-Maxwellian velocity distribution. We have developed an analytical model that improves the quantitative interpretation of head echo radar measurements and ionization efficiency (called the Beta parameter). This will help us calculate meteoroid and atmosphere parameters from radar head-echo observations. Non-specular meteor trail echoes develop when meteor plasmas become turbulent allowing the reflection of radar signals. We will analyze this system using 3D simulations of a dense column of meteor plasma embedded in a background ionosphere/thermosphere. While the meteor diffuses across the Earth's geomagnetic field B0, large electric fields develop because of the interplay between highly mobile but magnetized electrons and the heavier but collisionally demagnetized ions. These fields point mostly perpendicular to B0 and change slowly in the direction of B0. These simulations show that the electric field causes a substantial restructuring of the ionospheric plasma outside the trail but connected to it via B0. They also demonstrate the diffusive expansion of the trail and the development of waves both within and outside the trail

  9. Comparison of high-latitude thermospheric meridionalwinds I: optical and radar experimental comparisons

    Directory of Open Access Journals (Sweden)

    E. M. Griffin

    2004-03-01

    Full Text Available Thermospheric neutral winds at Kiruna, Sweden (67.4°N, 20.4°E are compared using both direct optical Fabry-Perot Interferometer (FPI measurements and those derived from European incoherent scatter radar (EISCAT measurements. This combination of experimental data sets, both covering well over a solar cycle of data, allows for a unique comparison of the thermospheric meridional component of the neutral wind as observed by different experimental techniques. Uniquely in this study the EISCAT measurements are used to provide winds for comparison using two separate techniques: the most popular method based on the work of Salah and Holt (1974 and the Meridional Wind Model (MWM (Miller et al., 1997 application of servo theory. The balance of forces at this location that produces the observed diurnal pattern are investigated using output from the Coupled Thermosphere and Ionosphere (CTIM numerical model. Along with detailed comparisons from short periods the climatological behaviour of the winds have been investigated for seasonal and solar cycle dependence using the experimental techniques. While there are features which are consistent between the 3 techniques, such as the evidence of the equinoctial asymmetry, there are also significant differences between the techniques both in terms of trends and absolute values. It is clear from this and previous studies that the high-latitude representation of the thermospheric neutral winds from the empirical Horizontal Wind Model (HWM, though improved from earlier versions, lacks accuracy in many conditions. The relative merits of each technique are discussed and while none of the techniques provides the perfect data set to address model performance at high-latitude, one or more needs to be included in future HWM reformulations.

    Key words. Meteorology and atmospheric dynamics (thermospheric dynamics, Ionosphere (ionosphere-atmosphere interactions, auroral ionosphere

  10. Gravity wave penetration into the thermosphere: sensitivity to solar cycle variations and mean winds

    Directory of Open Access Journals (Sweden)

    D. C. Fritts

    2008-12-01

    Full Text Available We previously considered various aspects of gravity wave penetration and effects at mesospheric and thermospheric altitudes, including propagation, viscous effects on wave structure, characteristics, and damping, local body forcing, responses to solar cycle temperature variations, and filtering by mean winds. Several of these efforts focused on gravity waves arising from deep convection or in situ body forcing accompanying wave dissipation. Here we generalize these results to a broad range of gravity wave phase speeds, spatial scales, and intrinsic frequencies in order to address all of the major gravity wave sources in the lower atmosphere potentially impacting the thermosphere. We show how penetration altitudes depend on gravity wave phase speed, horizontal and vertical wavelengths, and observed frequencies for a range of thermospheric temperatures spanning realistic solar conditions and winds spanning reasonable mean and tidal amplitudes. Our results emphasize that independent of gravity wave source, thermospheric temperature, and filtering conditions, those gravity waves that penetrate to the highest altitudes have increasing vertical wavelengths and decreasing intrinsic frequencies with increasing altitude. The spatial scales at the highest altitudes at which gravity wave perturbations are observed are inevitably horizontal wavelengths of ~150 to 1000 km and vertical wavelengths of ~150 to 500 km or more, with the larger horizontal scales only becoming important for the stronger Doppler-shifting conditions. Observed and intrinsic periods are typically ~10 to 60 min and ~10 to 30 min, respectively, with the intrinsic periods shorter at the highest altitudes because of preferential penetration of GWs that are up-shifted in frequency by thermospheric winds.

  11. Longitudinal Distribution of the Dayside Ionosphere of Mars at High Latitude

    Science.gov (United States)

    Haider, S. A.; Sheel, Varun; Singh, V.; Maguire, W. C.; Molina-Cuberos, G. J.

    2009-03-01

    Accelerometer and radio science data obtained from Mars Global Surveyor have been used to study the longitudinal structure of thermosphere and troposphere of Mars at high latitude region. These datasets represent primary and secondary ionization peaks at altitudes 130 km and 122 km, respectively. These peaks are reproduced by photoionization and photoelectron impact processes. The production rates of different ions are estimated in the thermosphere and troposphere at solar zenith angle 80°, using analytical yield spectrum and energy loss models, respectively. The electron densities are calculated under photochemical equilibrium condition. The impact ionization sources are taken as EUV and galactic cosmic rays. The characteristics of longitudinal distribution of production and density are fitted up to waves 2 and 3 by least square method with 0.95 confidence limits. The peak electron density in the troposphere is obtained at an altitude of 30 km due to high efficiency of electron attachment to Ox molecules, which entails that concentration of negative ions is higher than that of electron below 30 km. Of the 35 ions considered in the model, the densities of electron and nine major ions (H3O+(H2O)n for n = 1,2,3,4, notation="LaTeX">CO^{-}_{4}, notation="LaTeX">CO^{-}_{3}, notation="LaTeX">NO^{-}_{2}H_{2}O, and notation="LaTeX">CO^{-}_{3}(H_{2}O)_{n} for n = 1,2) are discussed.

  12. Phoenix Deepens Trenches on Mars (3D)

    Science.gov (United States)

    2008-01-01

    The Surface Stereo Imager on NASA's Phoenix Mars Lander took this anaglyph on Oct. 21, 2008, during the 145th Martian day, or sol. Phoenix landed on Mars' northern plains on May 25, 2008. The trench on the upper left, called 'Upper Cupboard,' is about 60 centimeters (24 inches) long and 3 centimeters (1 inch) deep. The trench in the middle,called 'Ice Man,' is about 30 centimeters (12 inches) long and 3 centimeters (1 inch) deep. The trench on the right, called 'La Mancha,' is about 31 centimeters (12 inches) and 5 centimeters (2 inches) deep. The Phoenix mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  13. Global mesospheric tidal winds observed by the high resolution Doppler imager on board the upper atmosphere research satellite

    Energy Technology Data Exchange (ETDEWEB)

    Morton, Y.T.; Lieberman, R.S.; Hays, P.B.; Ortland, D.A.; Marshall, A.R.; Wu, D.; Skinner, W.R.; Burrage, M.D.; Gell, D.A.; Yee, J.H.

    1993-06-18

    This paper presents results of mesospheric and lower thermospheric wind tides. The observations come from the high resolution doppler imager (HRDI) on board the upper atmosphere research satellite. From these observations, the authors report the observation of tidal effects on top of the meridonal winds observed in this region. Previous measurements have been mainly limited to radar measurements from fixed ground stations, which do not give consistent results, and do not provide a global picture of the wave structure.

  14. 2016 Mars Insight Mission Design and Navigation

    Science.gov (United States)

    Abilleira, Fernando; Frauenholz, Ray; Fujii, Ken; Wallace, Mark; You, Tung-Han

    2014-01-01

    Scheduled for a launch in the 2016 Earth to Mars opportunity, the Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) Mission will arrive to Mars in late September 2016 with the primary objective of placing a science lander on the surface of the Red Planet followed by the deployment of two science instruments to investigate the fundamental processes of terrestrial planet formation and evolution. In order to achieve a successful landing, the InSight Project has selected a launch/arrival strategy that satisfies the following key and driving requirements: (1) Deliver a total launch mass of 727 kg, (2) target a nominal landing site with a cumulative Delta V99 less than 30 m/s, and (3) approach EDL with a V-infinity upper limit of 3.941 km/s and (4) an entry flight-path angle (EFPA) of -12.5 +/- 0.26 deg, 3-sigma; the InSight trajectories have been designed such that they (5) provide UHF-band communications via Direct-To-Earth and MRO from Entry through landing plus 60 s, (6) with injection aimpoints biased away from Mars such that the probability of the launch vehicle upper stage impacting Mars is less than 1.0 X 10(exp 4) for fifty years after launch, and (7) non-nominal impact probabilities due to failure during the Cruise phase less than 1.0 X 10(exp 2).

  15. MIPAS temperature from the stratosphere to the lower thermosphere: comparison of version vM21 with ACE-FTS, MLS, OSIRIS, SABER, SOFIE and lidar measurements

    Directory of Open Access Journals (Sweden)

    M. García-Comas

    2014-07-01

    Full Text Available We present vM21 MIPAS temperatures from the lower stratosphere to the lower thermosphere, which cover all optimized resolution measurements performed by MIPAS in the Middle Atmosphere, Upper Atmosphere and NoctiLucent Cloud modes during its lifetime. i.e., from January 2005 to March 2012. The main upgrades with respect to the previous version of MIPAS temperatures (vM11 are the update of the spectroscopic database, the use of a different climatology of atomic oxygen and carbon dioxide, and the improvement of important technical aspects of the retrieval setup (temperature gradient along the line of sight and offset regularizations, apodization accuracy. Additionally, an updated version of ESA calibrated L1b spectra (5.02/5.06 is used. The vM21 temperatures correct the main systematic errors of the previous version because they on average provide a 1–2 K warmer stratopause and middle mesosphere, and a 6–10 K colder mesopause (except in high latitude summers and lower thermosphere. These lead to a remarkable improvement of MIPAS comparisons with ACE-FTS, MLS, OSIRIS, SABER, SOFIE and the two Rayleigh lidars at Mauna Loa and Table Mountain, that, with few specific exceptions, typically exhibit differences smaller than 1 K below 50 km and than 2 K at 50–80 km in spring, autumn, winter at all latitudes, and summer at low to mid-latitudes. Differences in the high latitude summers are typically smaller than 1 K below 50 km, smaller than 2 K at 50–65 km and 5 K at 65–80 km. Differences with the other instruments in the mid-mesosphere are generally negative. MIPAS mesopause is within 4 K of the other instruments measurements, except in the high latitude summers, where it is within 5–10 K of the other instruments, being warmer than SABER, MLS and OSIRIS and colder than ACE-FTS and SOFIE. The agreement in the lower thermosphere is typically better than 5 K, except for high latitudes during spring and summer, where MIPAS usually exhibits larger

  16. Thermosphere-Ionosphere-Mesosphere Modeling Using the TIME-GCM

    Science.gov (United States)

    2014-09-30

    of temperature, winds and composition of the upper atmosphere between 30 and 500 km altitude. Carbon Dioxide (CO2) is one of the species that the...and photodissociation of NO on the temperature and density structure of the terrestrial atmosphere,” J. Geophys. Res., in press, 2000. Walterscheid

  17. The Long, Bumpy Road to a Mars Aeronomy Mission (Invited)

    Science.gov (United States)

    Grebowsky, J. M.; Luhmann, J. G.; Bougher, S. W.; Jakosky, B. M.

    2013-12-01

    With the advent of the space age, early focus was put into characterizing the Earth's upper atmosphere with aeronomy missions. These missions were designed to study the upper atmosphere region of a planet where the ionosphere is produced with particular attention given to the composition, properties and motion of atmosphere constituents. In particular a very successful US series of Atmosphere Explorer aeronomy spacecraft (1963-1977) was implemented. This upper atmosphere region is the envelope that all energy from the sun must penetrate and is recognized as an inseparable part of a planet's entire atmosphere. Venus was the next planet to have its upper atmosphere/ionosphere deeply probed via the Pioneer Venus Orbiter (1978-1986) that carried a complement of instruments similar to some flown on the Atmosphere Explorers. The planet which humans have long set their imagination on, Mars, has yet to be subjected to the same detailed upper atmosphere perusal until now, with MAVEN. Not that attempts have been wanting. More than 30 spacecraft launches to Mars were attempted, but half were not successful and those that attained orbit came far short of attaining the same level of knowledge of the Martian upper atmosphere. Other countries had planned Mars aeronomy missions that didn't bear fruit - e.g. Mars-96 and Nozomi and the US did studies for two missions, Mars Aeronomy Orbiter and MUADEE, that never were implemented. This is about to change. NASA's Scout Program singled out two aeronomy missions in its final competition and the selected mission, MAVEN, will fly with the needed sophistication of instruments to finally probe and understand the top of Mars' atmosphere. Was this late selection of a NASA aeronomy mission to Mars a philosophy change in US priorities or was it an accident of planning and budget constraints? Was it driven by the developing knowledge that Mars really had an early atmosphere environment conducive to life and that an aeronomy mission is indeed

  18. Mars at Opposition

    Science.gov (United States)

    Riddle, Bob

    2010-01-01

    On January 29, Mars will reach opposition, a point along its orbit around the Sun where Mars will be directly opposite from the Sun in a two-planet and Sun line-up with the Earth in between. At this opposition, the Earth and Mars will be separated by nearly 100 million km. An opposition is similar to a full Moon in that the planet at opposition…

  19. Mars at Opposition

    Science.gov (United States)

    Riddle, Bob

    2010-01-01

    On January 29, Mars will reach opposition, a point along its orbit around the Sun where Mars will be directly opposite from the Sun in a two-planet and Sun line-up with the Earth in between. At this opposition, the Earth and Mars will be separated by nearly 100 million km. An opposition is similar to a full Moon in that the planet at opposition…

  20. Mars Museum Visualization Alliance

    Science.gov (United States)

    Sohus, A. M.; Viotti, M. A.; de Jong, E. M.

    2004-11-01

    The Mars Museum Visualization Alliance is a collaborative effort funded by the Mars Public Engagement Office and supported by JPL's Informal Education staff and the Solar System Visualization Project to share the adventure of exploration and make Mars a real place. The effort started in 2002 with a small working group of museum professionals to learn how best to serve museum audiences through informal science educators. By the time the Mars Exploration Rovers landed on Mars in January 2004, over 100 organizations were partners in the Alliance, which has become a focused community of Mars educators. The Alliance provides guaranteed access to images, information, news, and resources for use by the informal science educators with their students, educators, and public audiences. Thousands of people have shared the adventure of exploring Mars and now see it as a real place through the efforts of the Mars Museum Visualization Alliance partners. The Alliance has been lauded for "providing just the right inside track for museums to do what they do best," be that webcasts, live presentations with the latest images and information, high-definition productions, planetarium shows, or hands-on educational activities. The Alliance is extending its mission component with Cassini, Genesis, Deep Impact, and Stardust. The Mars Exploration and Cassini Programs, as well as the Genesis, Deep Impact, and Stardust Projects, are managed for NASA by the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California.

  1. Erosionsrinnen auf dem Mars

    OpenAIRE

    Reiß, Dennis Emil

    2010-01-01

    The work presented here analyses gullies on Mars using high resolution images (Mars Orbiter Camera – MOC) of the Mars Global Surveyor Mission (MGS). Gullies on Earth are formed by debris flows, a mass movement in which water is involved. It is assumed that gully features on Mars are young and therefore they could indicate the presence of liquid water in the recent past. The main focus of this work lies in a morphological analysis, a global mapping of their distribution and a determination of ...

  2. Digital cartography of Mars

    Science.gov (United States)

    Batson, R. M.

    1987-01-01

    A medium-resolution Digital Image Model (DIM) of Mars is being compiled. A DIM is a mosaic of radiometrically corrected, photometrically modelled spacecraft images displaying accurate reflectance properties at uniform resolution, and geometrically tied to the best available control. The Mars medium-resolution DIM contains approximately 4700 Viking Orbiter image frames that were used to compile the recently completed 1:2,000,000-scale controlled photomosaic series of Mars. This DIM provides a planimetric control base to which all other Mars maps will be registered. A similar control base of topographic elevations (Digital Terrain Model, or DTM) is also being compiled. These products are scheduled for completion in 1989.

  3. Interpretation of the mesospheric and lower thermospheric mean winds observed by MF radar at about 30°N with the 2D-SOCRATES model

    Science.gov (United States)

    Xiao, C. Y.; Hu, X.; Zhang, X. X.; Zhang, D. Y.; Wu, X. C.; Gong, X. Y.; Igarashi, K.

    Data obtained by Wuhan (30.5°N, 114.4°E) MF radar and Yamagawa (31.2°N, 130.6°E) MF radar have been used to study the mean winds in the mesosphere and lower thermosphere (MLT) at about 30°N. The observed mean zonal and mean meridional winds show obviously seasonal variations. Westerly wind prevails in winter, and decreases with the increasing height above 76 km, even reverses above 96 km sometimes. The summer mean zonal wind is westward in the mesosphere and eastward in the lower thermosphere, with the reversal height of about 80 km. From 70 to 95 km, the mean meridional wind blows northward in winter and southward in summer. Northerly wind prevails between 95 and 98 km throughout seasons. These wind features have similar patterns to those of the empirical HWM93 wind model. 2D-SOCRATES model is used to try to give physical interpretations of the observed wind fields, with which dynamic contributions to the MLT wind structures are analyzed. Simulations show that the planetary waves play an unimportant role in the MLT region since they have relatively small magnitudes during winter and even cannot propagate upward into the upper atmosphere during summer. The gravity waves play a crucial role in determining the wind structures in the MLT region, providing forcing of about 40 m/s/day and diffusion coefficients of about 50 m 2/s at 30°N. The atmospheric tidal waves have significant influences in the wind structures with forcing of about 10 m/s/day and diffusion coefficients of about several m 2/s in the MLT at 30°N. Breakings of these atmospheric waves tend to close off the westerly jet in winter and easterly jet in summer, to produce strong wind shear in the mesopause, and to drive the meridional wind directed from the summer hemisphere to the winter hemisphere.

  4. MAVEN observations of the response of Mars to an interplanetary coronal mass ejection.

    Science.gov (United States)

    Jakosky, B M; Grebowsky, J M; Luhmann, J G; Connerney, J; Eparvier, F; Ergun, R; Halekas, J; Larson, D; Mahaffy, P; McFadden, J; Mitchell, D F; Schneider, N; Zurek, R; Bougher, S; Brain, D; Ma, Y J; Mazelle, C; Andersson, L; Andrews, D; Baird, D; Baker, D; Bell, J M; Benna, M; Chaffin, M; Chamberlin, P; Chaufray, Y-Y; Clarke, J; Collinson, G; Combi, M; Crary, F; Cravens, T; Crismani, M; Curry, S; Curtis, D; Deighan, J; Delory, G; Dewey, R; DiBraccio, G; Dong, C; Dong, Y; Dunn, P; Elrod, M; England, S; Eriksson, A; Espley, J; Evans, S; Fang, X; Fillingim, M; Fortier, K; Fowler, C M; Fox, J; Gröller, H; Guzewich, S; Hara, T; Harada, Y; Holsclaw, G; Jain, S K; Jolitz, R; Leblanc, F; Lee, C O; Lee, Y; Lefevre, F; Lillis, R; Livi, R; Lo, D; Mayyasi, M; McClintock, W; McEnulty, T; Modolo, R; Montmessin, F; Morooka, M; Nagy, A; Olsen, K; Peterson, W; Rahmati, A; Ruhunusiri, S; Russell, C T; Sakai, S; Sauvaud, J-A; Seki, K; Steckiewicz, M; Stevens, M; Stewart, A I F; Stiepen, A; Stone, S; Tenishev, V; Thiemann, E; Tolson, R; Toublanc, D; Vogt, M; Weber, T; Withers, P; Woods, T; Yelle, R

    2015-11-01

    Coupling between the lower and upper atmosphere, combined with loss of gas from the upper atmosphere to space, likely contributed to the thin, cold, dry atmosphere of modern Mars. To help understand ongoing ion loss to space, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft made comprehensive measurements of the Mars upper atmosphere, ionosphere, and interactions with the Sun and solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes in the bow shock and magnetosheath, formation of widespread diffuse aurora, and enhancement of pick-up ions. Observations and models both show an enhancement in escape rate of ions to space during the event. Ion loss during solar events early in Mars history may have been a major contributor to the long-term evolution of the Mars atmosphere.

  5. Correlations Between Variations in Solar EUV and Soft X-Ray Irradiance and Photoelectron Energy Spectra Observed on Mars and Earth

    Science.gov (United States)

    Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

    2013-01-01

    Solar extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F(10.7) index currently used.

  6. Ionosphere-thermosphere (IT) response to solar wind forcing during magnetic storms

    Science.gov (United States)

    Huang, Cheryl Yu-Ying; Huang, Yanshi; Su, Yi-Jiun; Sutton, Eric K.; Rotan Hairston, Marc; Coley, William Robin

    2016-01-01

    During magnetic storms, there is a strong response in the ionosphere and thermosphere which occurs at polar latitudes. Energy input in the form of Poynting flux and energetic particle precipitation, and energy output in the form of heated ions and neutrals have been detected at different altitudes and all local times. We have analyzed a number of storms, using satellite data from the Defense Meteorological Satellite Program (DMSP), the Gravity Recovery and Climate Experiment (GRACE), Gravity field and steady-state Ocean Circulation Explorer (GOCE), and Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission. Poynting flux measured by instruments on four DMSP spacecraft during storms which occurred in 2011-2012 was observed in both hemispheres to peak at both auroral and polar latitudes. By contrast, the measured ion temperatures at DMSP and maxima in neutral density at GOCE and GRACE altitudes maximize in the polar region most frequently with little evidence of Joule heating at auroral latitudes at these spacecraft orbital locations.

  7. Evidence of meso-scale structure in the high-latitude thermosphere

    Directory of Open Access Journals (Sweden)

    A. L. Aruliah

    Full Text Available There is a widely held assumption that the thermospheric neutral gas is slow to respond to magnetospheric forcing owing to its large inertia and therefore, may be treated as a steady state background medium for the more dynamic ionosphere. This is shown to be over simplistic. The data presented here compare direct measurements of the thermospheric neutral winds made in Northern Scandinavia by Fabry-Perot Interferometers (FPIs with direct measurements of the ionosphere made by the EISCAT radar and with model simulations. These comparisons will show that the neutral atmosphere is capable of responding to ionospheric changes on mesoscale levels, i.e., spatial and temporal scale sizes of less than a few hundred kilometres and tens of minutes, respectively.

    Key words. Atmospheric composition and structure (air-glow and aurora; instruments and techniques – Ionosphere (ionosphere-atmosphere interactions

  8. Community-wide model validation studies for systematic assessment of ionosphere-thermosphere models

    Science.gov (United States)

    Shim, Ja Soon; Kuznetsova, Maria; Rastätter, Lutz

    2016-07-01

    As an unbiased agent, the Community Coordinated Modeling Center (CCMC) has been leading community-wide model validation efforts; GEM, CEDAR and GEM-CEDAR Modeling Challenges since 2009. The CEDAR ETI (Electrodynamics Thermosphere Ionosphere) Challenge focused on the ability of ionosphere-thermosphere (IT) models to reproduce basic IT system parameters, such as electron and neutral densities, NmF2, hmF2, and Total Electron Content (TEC). Model-data time series comparisons were performed for a set of selected events with different levels of geomagnetic activity (quiet, moderate, storms). The follow-on CEDAR-GEM Challenge aims to quantify geomagnetic storm impacts on the IT system. On-going studies include quantifying the storm energy input, such as increase in auroral precipitation and Joule heating, and quantifying the storm-time variations of neutral density and TEC. In this paper, we will present lessons learned from the Modeling Challenges led by the CCMC.

  9. Equatorial particle precipitation during magnetic storms and relationship to equatorial thermospheric heating

    Energy Technology Data Exchange (ETDEWEB)

    Tinsley, B.A.; Sahai, Y.; Biondi, M.A.; Meriwether J.W. Jr.

    1988-01-01

    We compare optical observations of ring current particle precipitation from a near equatorial site in Brazil with variations in the AE and Dst indices. Precipitation occurs during ring current injection when AE is large, but for AE large without ring current injection, little precipitation is seen. Comparisons are also made with 630-nm observations of thermospheric heating made simultaneously in Peru. The thermospheric temperatures have been corrected for instrumental drift and temperature enhancements of several hundred kelvins are present. It is not possible to associate clearly the heating with direct precipitation nor in the short term with transport of heat from higher latitudes. On a longer time scale it is likely that both mid-latitude ring current sources and high-latitude Joule heating sources are involved. copyright American Geophysical Union 1988

  10. Comparison of high-latitude thermospheric meridional winds I: optical and radar experimental comparisons

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, E.M.; Mueller-Wodarg, I.C.F.; Aruliah, A.; Aylward, A. [Atmospheric Physics Lab., Univ. Coll. London, London (United Kingdom)

    2004-07-01

    Thermospheric neutral winds at Kiruna, Sweden (67.4 N, 20.4 E) are compared using both direct optical fabry-perot interferometer (FPI) measurements and those derived from European incoherent scatter radar (EISCAT) measurements. This combination of experimental data sets, both covering well over a solar cycle of data, allows for a unique comparison of the thermospheric meridional component of the neutral wind as observed by different experimental techniques. Uniquely in this study the EISCAT measurements are used to provide winds for comparison using two separate techniques: the most popular method based on the work of Salah and Holt (1974) and the meridional wind model (MWM) (Miller et al., 1997) application of servo theory. The balance of forces at this location that produces the observed diurnal pattern are investigated using output from the coupled thermosphere and ionosphere (CTIM) numerical model. Along with detailed comparisons from short periods the climatological behaviour of the winds have been investigated for seasonal and solar cycle dependence using the experimental techniques. While there are features which are consistent between the 3 techniques, such as the evidence of the equinoctial asymmetry, there are also significant differences between the techniques both in terms of trends and absolute values. It is clear from this and previous studies that the high-latitude representation of the thermospheric neutral winds from the empirical horizontal wind model (HWM), though improved from earlier versions, lacks accuracy in many conditions. The relative merits of each technique are discussed and while none of the techniques provides the perfect data set to address model performance at high-latitude, one or more needs to be included in future HWM reformulations. (orig.)

  11. Comparison of high-latitude thermospheric meridionalwinds II: combined FPI, radar and model Climatologies

    Directory of Open Access Journals (Sweden)

    E. M. Griffin

    2004-03-01

    Full Text Available The climatological behaviour of the thermospheric meridional wind above Kiruna, Sweden (67.4°N, 20.4°E has been investigated for seasonal and solar cycle dependence using six different techniques, comprising both model and experimental sources. Model output from both the empirical Horizontal Wind Model (HWM (Hedin et al., 1988 and the numerical Coupled Thermosphere and Ionosphere Model (CTIM are compared to the measured behaviour at Kiruna, as a single site example. The empirical International Reference Ionosphere (IRI model is used as input to an implementation of servo theory, to provide another climatology combining empirical input with a theoretical framework. The experimental techniques have been introduced in a companion paper in this issue and provide climatologies from direct measurements, using Fabry-Perot Interferometers (FPI, together with 2 separate techniques applied to the European Incoherent Scatter radar (EISCAT database to derive neutral winds. One of these techniques uses the same implementation of servo theory as has been used with the IRI model. Detailed comparisons for each season and solar activity category allow for conclusions to be drawn as to the major influences on the climatological behaviour of the wind at this latitude. Comparison of the incoherent scatter radar (ISR derived neutral winds with FPI, empirical model and numerical model winds is important to our understanding and judgement of the validity of the techniques used to derive thermospheric wind databases. The comparisons also test model performance and indicate possible reasons for differences found between the models. In turn, the conclusions point to possible improvements in their formulation. In particular it is found that the empirical models are over-reliant on mid-latitude data in their formulation, and fail to provide accurate estimates of the winds at high-latitudes.

    Key words. Meteorology and atmospheric dynamics (thermospheric dynamics

  12. Intraannual variability of tides in the thermosphere from model simulations and in situ satellite observations

    Science.gov (United States)

    Häusler, K.; Hagan, M. E.; Forbes, J. M.; Zhang, X.; Doornbos, E.; Bruinsma, S.; Lu, G.

    2015-01-01

    In this paper, we provide insights into limitations imposed by current satellite-based strategies to delineate tidal variability in the thermosphere, as well as the ability of a state-of-the-art model to replicate thermospheric tidal determinations. Toward this end, we conducted a year-long thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) simulation for 2009, which is characterized by low solar and geomagnetic activity. In order to account for tropospheric waves and tides propagating upward into the ˜30-400 km model domain, we used 3-hourly MERRA (Modern-Era Retrospective Analysis for Research and Application) reanalysis data. We focus on exospheric tidal temperatures, which are also compared with 72 day mean determinations from combined Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellite observations to assess the model's capability to capture the observed tidal signatures and to quantify the uncertainties associated with the satellite exospheric temperature determination technique. We found strong day-to-day tidal variability in TIME-GCM that is smoothed out when averaged over as few as ten days. TIME-GCM notably overestimates the 72 day mean eastward propagating tides observed by CHAMP/GRACE, while capturing many of the salient features of other tidal components. However, the CHAMP/GRACE tidal determination technique only provides a gross climatological representation, underestimates the majority of the tidal components in the climatological spectrum, and moreover fails to characterize the extreme variability that drives the dynamics and electrodynamics of the ionosphere-thermosphere system. A multisatellite mission that samples at least six local times simultaneously is needed to provide this quantification.

  13. Utilizing Probability Distribution Functions and Ensembles to Forecast lonospheric and Thermosphere Space Weather

    Science.gov (United States)

    2016-04-26

    created using probability distribution functions. This new model performs as well or better than other modern models of the solar wind velocity. In... Physics , 120: 7987-8001, doi: 10.1002/2014JA020962. Abstract: The temporal and spatial variations of the thermospheric mass density during a series of...2015), Theoretical study of zonal differences of electron density at midlatitudes with GITM simulation, J. Geophys. Res. Space Physics , 120, 2951

  14. Cancer Risk Map for the Surface of Mars

    Science.gov (United States)

    Kim, Myung-Hee Y.; Cucinotta, Francis A.

    2011-01-01

    We discuss calculations of the median and 95th percentile cancer risks on the surface of Mars for different solar conditions. The NASA Space Radiation Cancer Risk 2010 model is used to estimate gender and age specific cancer incidence and mortality risks for astronauts exploring Mars. Organ specific fluence spectra and doses for large solar particle events (SPE) and galactic cosmic rays (GCR) at various levels of solar activity are simulated using the HZETRN/QMSFRG computer code, and the 2010 version of the Badhwar and O Neill GCR model. The NASA JSC propensity model of SPE fluence and occurrence is used to consider upper bounds on SPE fluence for increasing mission lengths. In the transport of particles through the Mars atmosphere, a vertical distribution of Mars atmospheric thickness is calculated from the temperature and pressure data of Mars Global Surveyor, and the directional cosine distribution is implemented to describe the spherically distributed atmospheric distance along the slant path at each elevation on Mars. The resultant directional shielding by Mars atmosphere at each elevation is coupled with vehicle and body shielding for organ dose estimates. Astronaut cancer risks are mapped on the global topography of Mars, which was measured by the Mars Orbiter Laser Altimeter. Variation of cancer risk on the surface of Mars is due to a 16-km elevation range, and the large difference is obtained between the Tharsis Montes (Ascraeus, Pavonis, and Arsia) and the Hellas impact basin. Cancer incidence risks are found to be about 2-fold higher than mortality risks with a disproportionate increase in skin and thyroid cancers for all astronauts and breast cancer risk for female astronauts. The number of safe days on Mars to be below radiation limits at the 95th percent confidence level is reported for several Mission design scenarios.

  15. Microscope on Mars

    Science.gov (United States)

    2004-01-01

    This image taken at Meridiani Planum, Mars by the panoramic camera on the Mars Exploration Rover Opportunity shows the rover's microscopic imager (circular device in center), located on its instrument deployment device, or 'arm.' The image was acquired on the ninth martian day or sol of the rover's mission.

  16. Microscope on Mars

    Science.gov (United States)

    2004-01-01

    This image taken at Meridiani Planum, Mars by the panoramic camera on the Mars Exploration Rover Opportunity shows the rover's microscopic imager (circular device in center), located on its instrument deployment device, or 'arm.' The image was acquired on the ninth martian day or sol of the rover's mission.

  17. Superposed epoch analysis of storm time response of the ionosphere-thermosphere (IT) system

    Science.gov (United States)

    Oliveira, D. M.; Zesta, E.; Connor, H.; Su, Y. J.; Sutton, E. K.; Huang, C. Y.; Ober, D. M.; Delay, S. H.; Schuck, P. W.

    2015-12-01

    The thermosphere-ionosphere system response to energy input by Joule heating via Poynting flux and auroral precipitation is strongly intensified during times with high geomagnetic activity or during geomagnetic storms. The most dramatic thermospheric response is the intensification and upwelling of the thermospheric mass density. The neutral mass density is not only a key parameter to understanding the solar wind - IT coupling, but also plays an important role in understanding satellite orbital drag, which in turn impacts satellite position predictions. Results of numerical simulations and satellite observations (CHAMP and GRACE) have shown that the neutral mass density is rapidly intensified (within minutes) after the initial storm shock impact and also after the onset of storm main phase. This almost immediate response is typical of CME-driven storms in which the neutral density is enhanced first in the dayside polar cap and the intensification subsequently spreads out to all magnetic local time regions and lower latitude regions. We perform a superposed epoch analysis using CHAMP and GRACE satellite data as well as DMSP data to study the spatial and temporal distribution of the measured Poynting flux and neutral density response during the main phase of storms of different intensity. We also examine the correlation characteristics between Poynting flux and neutral density response, in space and time during the storm.

  18. Thermosphere and geomagnetic response to interplanetary coronal mass ejections observed by ACE and GRACE: Statistical results

    CERN Document Server

    Krauss, S; Veronig, A M; Baur, O; Lammer, H

    2015-01-01

    For the period July 2003 to August 2010, the interplanetary coronal mass ejection (ICME) catalogue maintained by Richardson and Cane lists 106 Earth-directed events, which have been measured in-situ by plasma and field instruments onboard the ACE satellite. We present a statistical investigation of the Earth's thermospheric neutral density response by means of accelerometer measurements collected by the GRACE satellites, which are available for 104 ICMEs in the data set, and its relation to various geomagnetic indices and characteristic ICME parameters such as the impact speed, southward magnetic field strength (Bz). The majority of ICMEs causes a distinct density enhancement in the thermosphere, with up to a factor of eight compared to the pre-event level. We find high correlations between ICME Bz and thermospheric density enhancements (~0.9), while the correlation with the ICME impact speed is somewhat smaller (~0.7). The geomagnetic indices revealing the highest correlations are Dst and SYM-H (~0.9), the l...

  19. Wavelength Dependence of Solar Flare Irradiation and its Influence on the Thermosphere

    Science.gov (United States)

    Huang, Yanshi; Richmond, Arthur D.; Deng, Yue; Qian, L.; Solomon, S.; Chamberlin, P.

    2012-01-01

    The wavelength dependence of solar flare enhancement is one of the important factors determining how the Thermosphere-Ionosphere (T-I) system response to flares. To investigate the wavelength dependence of solar flare, the Flare Irradiance Spectral Model (FISM) has been run for 34 X-class flares. The results show that the percentage increases of solar irradiance at flare peak comparing to pre-flare condition have a clear wavelength dependence. In the wavelength range between 0 - 195 nm, it can vary from 1% to 10000%. The solar irradiance enhancement is largest ( 1000%) in the XUV range (0 - 25 nm), and is about 100% in EUV range (25 - 120 nm). The influence of different wavebands on the T-I system during the October 28th, 2003 flare (X17.2-class) has also been examined using the latest version of National Center for Atmospheric Research (NCAR) Thermosphere- Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). While the globally integrated solar energy deposition is largest in the 0 - 14 nm waveband, the impact of solar irradiance enhancement on the thermosphere at 400 km is largest for 25 - 105 nm waveband. The effect of 122 - 195 nm is small in magnitude, but it decays slowly.

  20. 3-D GCM modelling of thermospheric nitric oxide during the 2003 Halloween storm

    Energy Technology Data Exchange (ETDEWEB)

    Dobbin, A.L.; Griffin, E.M.; Aylward, A.D.; Millward, G.H. [University College London (United Kingdom). Atmospheric Physics Lab.

    2006-07-01

    Numerical modelling of thermospheric temperature changes associated with periods of high geomagnetic activity are often inaccurate due to unrealistic representation of nitric oxide (NO) densities and associated 5.3-{mu}m radiative cooling. In previous modelling studies, simplistic parameterisations of NO density and variability have often been implemented in order to constrain thermospheric temperature predictions and post storm recovery timescales during and following periods of high auroral activity. In this paper we use the University College London (UCL) 3-D Coupled Thermosphere and Middle Atmosphere (CMAT) General Circulation Model to simulate the 11-day period from 23 October to 3 November 2003, during which the Earth experienced some of the largest geomagnetic activity ever recorded; the so called ''Halloween storm''. This model has recently been updated to include a detailed self consistent calculation of NO production and transport. Temperatures predicted by the model compare well with those observed by the UCL Fabry Perot Interferometer at Kiruna, northern Sweden, when changes in solar and auroral activity are taken into account in the calculation of NO densities. The spatial distribution of predicted temperatures at approximately 250-km altitude is also discussed. Simulated NO densities at approximately 110 km are presented. Large quantities of NO are found to be present at to the equator, one to two days after the most intense period of geomagnetic activity. This is the first 3-D GCM simulation of NO production and transport over the 2003 Halloween storm period. (orig.)

  1. Universal time effect in the response of the thermosphere to electric field changes

    Science.gov (United States)

    Perlongo, N. J.; Ridley, A. J.

    2016-04-01

    Understanding the dynamics of the thermospheric mass density is of paramount importance for predicting drag on low-altitude satellites, particularly during geomagnetic storms. Transient enhancements in ion velocities, which frequently occur as a result of storm-driven solar wind electric field fluctuations, cause increases in neutral density and temperature. Since the Earth's quasi-dipolar magnetic field is tilted and offset from the center of the planet, it is hypothesized that hemispheric asymmetries arise, altering the thermospheric response to energy input based upon the time of day. This study used the Global Ionosphere-Thermosphere Model (GITM) to investigate this phenomenon via a series of 22 idealized simulations, where the convective electric field was enhanced for 1 h of the day. Two configurations of the Earth's magnetic field were considered, the International Geomagnetic Reference Field (IGRF) and a centered dipole. These runs were conducted at March equinox when the amount of sunlight falling on the two hemispheres was the same. Two additional sets of runs were conducted at the June and December solstices for comparison. It was found that the most geoeffective times were those times when the geomagnetic poles were pointed toward the Sun. This orientation maximizes the photoionization colocated with the high-latitude potential pattern, leading to more in Joule heating.

  2. Evidence for Solar Cycle Influence on the Infrared Energy Budget and Radiative Cooling of the Thermosphere

    Science.gov (United States)

    Mlynczak, Martin G.; Martin-Torres, F. Javier; Marshall, B. Thomas; Thompson, R. Earl; Williams, Joshua; Turpin, TImothy; Kratz, D. P.; Russell, James M.; Woods, Tom; Gordley, Larry L.

    2007-01-01

    We present direct observational evidence for solar cycle influence on the infrared energy budget and radiative cooling of the thermosphere. By analyzing nearly five years of data from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument, we show that the annual mean infrared power radiated by the nitric oxide (NO) molecule at 5.3 m has decreased by a factor of 2.9. This decrease is correlated (r = 0.96) with the decrease in the annual mean F10.7 solar index. Despite the sharp decrease in radiated power (which is equivalent to a decrease in the vertical integrated radiative cooling rate), the variability of the power as given in the standard deviation of the annual means remains approximately constant. A simple relationship is shown to exist between the infrared power radiated by NO and the F10.7 index, thus providing a fundamental relationship between solar activity and the thermospheric cooling rate for use in thermospheric models. The change in NO radiated power is also consistent with changes in absorbed ultraviolet radiation over the same time period.

  3. Ionospheric Spread-F and couplings between thermosphere and lower atmosphere (Invited)

    Science.gov (United States)

    Xiao, Z.

    2010-12-01

    Ionospheric Spread-F is a widely studied subject due to its significance in understanding physical essentials of the ionospheric irregularities and applications in scintillations prediction of radio wave propagation. The occurrence of Spread-F is affected by many factors such as density gradient below the F2 peak, neutral wind, electric field and so on. All these factors are necessary as the background for Spread-F to occur while not sufficient. There seems some triggering mechanisms are needed for spread-F to onset. Among the triggering factors, acoustic gravity wave is very important in seeding Spread-F occurring. In this paper, observational evidences based on ionospheric HF Doppler measurements are provided to show that in many cases spread-F are accompanied with wave-like disturbances, especially, when the amplitudes of such disturbances are large. These kinds of wave-like disturbances are known as acoustic gravity waves. We recognized these waves are originated from severe disturbances in the lower atmosphere such as typhoon, volcano eruption and some post-earthquake effects. Although many statistics indicate that Spread-F is correlated with solar and geomagnetic activities the occurrence of it is not controlled directly by any solar events such as flares or CME. Thus, in a sense, Spread-F is a manifestation of couplings between thermosphere and lower atmosphere and it might be a hint for us to explain some regional features of thermosphere by the different conditions of lower atmosphere under thermosphere.

  4. Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI): Instrument Design and Calibration

    Science.gov (United States)

    Englert, Christoph R.; Harlander, John M.; Brown, Charles M.; Marr, Kenneth D.; Miller, Ian J.; Stump, J. Eloise; Hancock, Jed; Peterson, James Q.; Kumler, Jay; Morrow, William H.; Mooney, Thomas A.; Ellis, Scott; Mende, Stephen B.; Harris, Stewart E.; Stevens, Michael H.; Makela, Jonathan J.; Harding, Brian J.; Immel, Thomas J.

    2017-04-01

    The Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument was built for launch and operation on the NASA Ionospheric Connection Explorer (ICON) mission. The instrument was designed to measure thermospheric horizontal wind velocity profiles and thermospheric temperature in altitude regions between 90 km and 300 km, during day and night. For the wind measurements it uses two perpendicular fields of view pointed at the Earth's limb, observing the Doppler shift of the atomic oxygen red and green lines at 630.0 nm and 557.7 nm wavelength. The wavelength shift is measured using field-widened, temperature compensated Doppler Asymmetric Spatial Heterodyne (DASH) spectrometers, employing low order échelle gratings operating at two different orders for the different atmospheric lines. The temperature measurement is accomplished by a multichannel photometric measurement of the spectral shape of the molecular oxygen A-band around 762 nm wavelength. For each field of view, the signals of the two oxygen lines and the A-band are detected on different regions of a single, cooled, frame transfer charge coupled device (CCD) detector. On-board calibration sources are used to periodically quantify thermal drifts, simultaneously with observing the atmosphere. The MIGHTI requirements, the resulting instrument design and the calibration are described.

  5. Wavelength Dependence of Solar Irradiance Enhancement During X-Class Flares and Its Influence on the Upper Atmosphere

    Science.gov (United States)

    Huang, Yanshi; Richmond, Arthur D.; Deng, Yue; Chamberlin, Phillip C.; Qian, Liying; Solomon, Stanley C.; Roble, Raymond G.; Xiao, Zuo

    2013-01-01

    The wavelength dependence of solar irradiance enhancement during flare events is one of the important factors in determining how the Thermosphere-Ionosphere (T-I) system responds to flares. To investigate the wavelength dependence of flare enhancement, the Flare Irradiance Spectral Model (FISM) was run for 61 X-class flares. The absolute and the percentage increases of solar irradiance at flare peaks, compared to pre-flare conditions, have clear wavelength dependences. The 0-14 nm irradiance increases much more (approx. 680% on average) than that in the 14-25 nm waveband (approx. 65% on average), except at 24 nm (approx. 220%). The average percentage increases for the 25-105 nm and 122-190 nm wavebands are approx. 120% and approx. 35%, respectively. The influence of 6 different wavebands (0-14 nm, 14-25 nm, 25-105 nm, 105- 120 nm, 121.56 nm, and 122-175 nm) on the thermosphere was examined for the October 28th, 2003 flare (X17-class) event by coupling FISM with the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) under geomagnetically quiet conditions (Kp=1). While the enhancement in the 0-14 nm waveband caused the largest enhancement of the globally integrated solar heating, the impact of solar irradiance enhancement on the thermosphere at 400 km is largest for the 25-105 nm waveband (EUV), which accounts for about 33 K of the total 45 K temperature enhancement, and approx. 7.4% of the total approx. 11.5% neutral density enhancement. The effect of 122-175 nm flare radiation on the thermosphere is rather small. The study also illustrates that the high-altitude thermospheric response to the flare radiation at 0-175 nm is almost a linear combination of the responses to the individual wavebands. The upper thermospheric temperature and density enhancements peaked 3-5 h after the maximum flare radiation.

  6. Neutral wind and density perturbations in the thermosphere created by gravity waves observed by the TIDDBIT sounder

    Science.gov (United States)

    Vadas, Sharon L.; Crowley, Geoff

    2017-06-01

    In this paper, we study the 10 traveling ionospheric disturbances (TIDs) observed at zobs˜283 km by the TIDDBIT ionospheric sounder on 30 October 2007 at 0400-0700 UT near Wallops Island, USA. These TIDs propagated northwest/northward and were previously found to be secondary gravity waves (GWs) from tropical storm Noel. An instrumented sounding rocket simultaneously measured a large neutral wind peak uH' with a similar azimuth at z ˜ 325 km. Using the measured TID amplitudes and wave vectors from the TIDDBIT system, together with ion-neutral theory, GW dissipative polarization relations and ray tracing, we determine the GW neutral horizontal wind and density perturbations as a function of altitude from 220 to 380 km. We find that there is a serious discrepancy between the GW dissipative theory and the observations unless the molecular viscosity, μ, decreases with altitude in the middle to upper thermosphere. Assuming that μ∝ρ¯q, where ρ¯ is the density, we find using GW dissipative theory that the GWs could have been observed at zobs and that one or more of the GWs could have caused the uH' wind peak at z≃325 km if q ˜ 0.67 for z≥220 km. This implies that the kinematic viscosity, ν=μ/ρ¯, increases less rapidly with altitude for z≥220 km: ν∝1/ρ¯0.33. This dependence makes sense because as ρ¯→0, the distance between molecules goes to infinity, which implies no molecular collisions and therefore no molecular viscosity μ.

  7. On Modeling the Upper Atmosphere and Ionosphere Response to Global Change

    Science.gov (United States)

    Roble, R. G.; Solomon, S. C.

    2005-05-01

    Ice core records indicate that the temperature and composition of the atmosphere can change significantly over geologic times. These changes occur naturally, however, recently the releases of trace gases from human activity have been recognized to have a potential for causing a significant change in the climate of the Earth. Most of the effort in investigating the global response to these trace gases has been directed toward the troposphere and stratosphere. Studies have shown that the troposphere will warm and the stratosphere will cool as trace gas concentrations increase in the 21st century. Studies have also been made that suggest that the mesosphere and thermosphere could also cool and affect the compositional structure of the upper atmosphere and ionosphere. We first review previous studies of the upper atmosphere and ionosphere response to trace gas increases. We then use both a global average model and the NCAR Thermosphere - Ionosphere - Mesosphere - Electrodynamics General Circulation Model (TIME-GCM) to investigate the atmospheric response to various scenarios of trace gas increases and compare the modeling results to the present day upper atmosphere and ionosphere structure. We will also discuss the key aeronomic processes that control the structure of the upper atmosphere as well as the extent to which these processes are known.

  8. ExoMars 2016 arrives at Mars

    Science.gov (United States)

    Svedhem, Hakan; Vago, Jorge L.; ExoMars Team

    2016-10-01

    The Trace Gas Orbiter (TGO) and the Schiaparelli Entry, descent and landing Demonstrator Model (EDM) will arrive at Mars on 19 October 2016. The TGO and the EDM are part of the first step of the ExoMars Programme. They will be followed by a Rover and a long lived Surface Platform to be launched in 2020.The EDM is attached to the TGO for the full duration of the cruise to Mars and will be separated three days before arrival at Mars. After separation the TGO will perform a deflection manoeuvre and, on 19 October (during the EDM landing), enter into a highly elliptical near equatorial orbit. TGO will remain in this parking orbit until January 2017, when the orbital plane inclination will be changed to 74 degrees and aerobraking to the final 400 km near circular orbit will start. The final operational orbit is expected to be reached at the end of 2017.The TGO scientific payload consists of four instruments. These are: ACS and NOMAD, both infrared spectrometers for atmospheric measurements in solar occultation mode and in nadir mode, CASSIS, a multichannel camera with stereo imaging capability, and FREND, an epithermal neutron detector for search of subsurface hydrogen. The mass of the TGO is 3700 kg, including fuel. The EDM, with a mass of 600 kg, is mounted on top of the TGO as seen in its launch configuration. The main objective of the EDM is to demonstrate the capability of performing a safe entry, descent and landing on the surface, but it does carry a descent camera and a small battery powered meteorological package that may operate for a few days on the surface.The ExoMars programme is a joint activity by the European Space Agency(ESA) and ROSCOSMOS, Russia. ESA is providing the TGO spacecraft and Schiaparelli (EDM) and two of the TGO instruments and ROSCOSMOS is providing the launcher and the other two TGO instruments. After the arrival of the ExoMars 2020 mission at the surface of Mars, the TGO will handle the communication between the Earth and the Rover and

  9. MARS: a status report

    Energy Technology Data Exchange (ETDEWEB)

    Tribble, R.E.; Gagliardi, C.A.; Liu, W. (Cyclotron Inst., Texas A and M Univ., College Station (USA))

    1991-05-01

    We are building a momentum achromat recoil spectrometer (MARS) for use with the new K500 superconducting cyclotron at Texas A and M University. MARS uses a unique optical design utilizing two dispersive planes to combine a momemtum achromat with a recoil mass spectrometer. This configuration makes MARS applicable to a broad range of nuclear reaction studies utilizing inverse kinematics. It also leads to a system that is well matched to the range of secondary particle energies that will be produced in reactions with K500 beam. MARS will have a typical mass resolution of {delta}M/M{approx equal}1/300, with an energy acceptance of {+-}9% {Delta}E/E and a geometric solid angle of up to 9 msr. A beam swinger system will alow reaction products in the angular range 0deg to 30deg to be studied. MARS will be used to study both the excited states and decay properties of very proton- and neutron-rich nuclei. MARS will also be used to provide a reaction mechanism filter to assist investigations of the dynamics of heavy ion collisions and to produce secondary radioactive beams for reaction and spectroscopic studies of particular interest for nuclear astrophysics. We briefly describe the design of MARS, give a status report on its construction and an overview of the scientific program planned for it. (orig.).

  10. Tidal coupling through the middle/upper atmosphere

    Science.gov (United States)

    Ward, William E.; Das, Uma; Du, Jian

    2016-07-01

    Although they have been studied for many years, atmospheric tides are still less well understood than often thought. It is now accepted that non-migrating tides are a significant component of the tidal signatures throughout the mesosphere and lower thermosphere. In general they are created in the troposphere and stratosphere through solar heating and propagate up into the thermosphere. However, the height profile of the amplitudes of individual component are not as smooth as expected, and short term (less than a few weeks) correlations of amplitude variations do not occur throughout the whole height domain. Our understanding of their dissipation also appears incomplete as in general the amplitudes of individual components do not become unstable. There are also issues in cleanly identifying the global form of individual components from ground based and satellite observations because of coverage and aliasing issues. In this presentation, our current understanding of tides and their influence on the middle/upper atmosphere will be reviewed and the possibility that some of our issues in understanding them might be resolved by thinking of them as a network of components discussed.

  11. El Niño influence on the mesosphere/lower thermosphere circulation at midlatitudes as seen by a VHF meteor radar at Collm (51.3 ° N, 13 ° E)

    Science.gov (United States)

    Jacobi, Christoph; Ermakova, Tatiana; Mewes, Daniel; Pogoreltsev, Alexander I.

    2017-09-01

    Mesosphere/lower thermosphere (MLT) zonal winds continuously measured by a VHF meteor radar at Collm, Germany (51.3° N, 13.0° E) in the height range 82 - 97 km from 2004 to date are analyzed with respect to the signature of El Niño. The comparison of Niño3 equatorial SST index and MLT wind time series shows that in January and especially in February zonal winds are positively correlated with the Niño3 index. We note a delay of about one month of the MLT zonal wind effect with respect to equatorial sea surface temperature variability. The signal is strong for the upper altitudes (above 90 km) accessible to the radar observations, but weakens with decreasing height. This reflects the fact that during El Niño years the westerly winter middle atmosphere wind jet is weaker, and this is also the case with the easterly lower thermospheric jet. Owing to the reversal of the absolute El Niño signal from negative to positive with altitude, at the height of the maximum meteor flux, which is around 90 km, the El Niño signal is weak. The experimental results can be qualitatively reproduced by numerical experiments using a mechanistic global circulation model with prescribed tropospheric temperatures and latent heat release for El Niño and La Niña conditions.

  12. El Niño influence on the mesosphere/lower thermosphere circulation seen by a VHF meteor radar at Collm (51.3°N, 13°E)

    Science.gov (United States)

    Jacobi, Christoph; Mewes, Daniel; Stober, Gunter; Pogoreltsev, Alexander

    2017-04-01

    Mesosphere/lower thermosphere (MLT) zonal winds continuously measured by a VHF meteor radar at Collm, Germany (51.3°N, 13.0°E) in the height range 82 - 97 km from 2004 to date are analyzed with respect to the signature of El Niño. The comparison of Niño3 equatorial SST index and MLT wind time series shows that in January and especially in February zonal winds are positively correlated with the Niño3 index. We note a delay of about 1 month of the MLT zonal wind effect with respect to equatorial sea surface temperature variability. The signal is strong for the upper altitudes (above 90 km) accessible to the radar observations, but weakens with decreasing height. This reflects the fact that during El Niño years the westerly winter middle atmosphere wind jet is weaker, and this is also the case with the easterly lower thermospheric jet. Owing to the reversal of the absolute El Niño signal from negative to positive with altitude, at the height of the maximum meteor flux, which is around 90 km, the El Niño signal is weak. The experimental results can be qualitatively reproduced by numerical experiments using a mechanistic global circulation model with prescribed tropospheric temperatures and latent heat release for El Niño and La Niña conditions.

  13. Evidence for Recent Liquid Water on Mars

    Science.gov (United States)

    2000-01-01

    Gullies eroded into the wall of a meteor impact crater in Noachis Terra. This high resolution view (top left) from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) shows channels and associated aprons of debris that are interpreted to have formed by groundwater seepage, surface runoff, and debris flow. The lack of small craters superimposed on the channels and apron deposits indicates that these features are geologically young. It is possible that these gullies indicate that liquid water is present within the martian subsurface today. The MOC image was acquired on September 28, 1999. The scene covers an area approximately 3 kilometers (1.9 miles) wide by 6.7 km (4.1 mi) high (note, the aspect ratio is 1.5 to 1.0). Sunlight illuminates this area from the upper left. The image is located near 54.8S, 342.5W. The context image (above) shows the location of the MOC image on the south-facing wall of an impact crater approximately 20 kilometers (12 miles) in diameter. The context picture was obtained by the Viking 1 orbiter in 1980 and is illuminated from the upper left. The large mound on the floor of the crater in the context view is a sand dune field. The Mars Orbiter Camera high resolution images are taken black-and-white (grayscale); the color seen here has been synthesized from the colors of Mars observed by the MOC wide angle cameras and by the Viking Orbiters in the late 1970s. A brief description of how the color was generated: The MOC narrow angle camera only takes grayscale (black and white) pictures. To create the color versions seen here, we have taken much lower resolution red and blue images acquired by the MOC's wide angle cameras, and by the Viking Orbiter cameras in the 1970s, synthesized a green image by averaging red and blue, and created a pallete of colors that represent the range of colors on Mars. We then use a relationship that correlates color and brightness to assign a color to each gray level. This is only a crude approximation of

  14. Estimation of energy budget of ionosphere-thermosphere system during two CIR-HSS events: observations and modeling

    Science.gov (United States)

    Verkhoglyadova, Olga; Meng, Xing; Mannucci, Anthony J.; Tsurutani, Bruce T.; Hunt, Linda A.; Mlynczak, Martin G.; Hajra, Rajkumar; Emery, Barbara A.

    2016-04-01

    We analyze the energy budget of the ionosphere-thermosphere (IT) system during two High-Speed Streams (HSSs) on 22-31 January, 2007 (in the descending phase of solar cycle 23) and 25 April-2 May, 2011 (in the ascending phase of solar cycle 24) to understand typical features, similarities, and differences in magnetosphere-ionosphere-thermosphere (IT) coupling during HSS geomagnetic activity. We focus on the solar wind energy input into the magnetosphere (by using coupling functions) and energy partitioning within the IT system during these intervals. The Joule heating is estimated empirically. Hemispheric power is estimated based on satellite measurements. We utilize observations from TIMED/SABER (Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry) to estimate nitric oxide (NO) and carbon dioxide (CO2) cooling emission fluxes. We perform a detailed modeling study of these two similar HSS events with the Global Ionosphere-Thermosphere Model (GITM) and different external driving inputs to understand the IT response and to address how well the model reproduces the energy transport. GITM is run in a mode with forecastable inputs. It is shown that the model captures the main features of the energy coupling, but underestimates NO cooling and auroral heating in high latitudes. Lower thermospheric forcing at 100 km altitude is important for correct energy balance of the IT system. We discuss challenges for a physics-based general forecasting approach in modeling the energy budget of moderate IT storms caused by HSSs.

  15. Mars Observer's costly solitude

    Science.gov (United States)

    Travis, John

    1993-09-01

    An evaluation is presented of the ramifications of the loss of contact with the Mars Observer spacecraft in August, 1993; the Observer constituted the first NASA mission to Mars in 17 years. It is noted that most, if not all of the scientists involved with the mission will have to find alternative employment within 6 months. The loss of the Observer will leave major questions concerning the geologic history of Mars, and its turbulent atmospheric circulation, unanswered. A detailed account of the discovery of the loss of communications, the unsuccessful steps taken to rectify the problem, and the financial losses incurred through the failure of the mission, are also given.

  16. Methane on Mars: Measurements and Possible Origins

    Science.gov (United States)

    Mumma, Michael J.; Villanueva, Geronimo L.; Novak, Robert E.; Radeva, Yana L.; Kaufl, H. Ulrich; Tokunaga, Alan; Encrenaz, Therese; Hartogh, Paul

    2011-01-01

    The presence of abundant methane in Earth's atmosphere (1.6 parts per million) requires sources other than atmospheric chemistry. Living systems produce more than 90% of Earth's atmospheric methane; the balance is of geochemical origin. On Mars, methane has been sought for nearly 40 years because of its potential biological significance, but it was detected only recently [1-5]. Its distribution on the planet is found to be patchy and to vary with time [1,2,4,5], suggesting that methane is released recently from the subsurface in localized areas, and is then rapidly destroyed [1,6]. Before 2000, searchers obtained sensitive upper limits for methane by averaging over much of Mars' dayside hemisphere, using data acquired by Marsorbiting spacecraft (Mariner 9) and Earth-based observatories (Kitt Peak National Observatory, Canada- France-Hawaii Telescope, Infrared Space Observatory). These negative findings suggested that methane should be searched at higher spatial resolution since the local abundance could be significantly larger at active sites. Since 2001, searches for methane have emphasized spatial mapping from terrestrial observatories and from Mars orbit (Mars Express).

  17. The Gravity Field of Mars From MGS, Mars Odyssey, and MRO Radio Science

    Science.gov (United States)

    Genova, Antonio; Goossens, Sander; Lemoine, Frank G.; Mazarico, Erwan; Smith, David E.; Zuber, Maria T.

    2015-01-01

    The Mars Global Surveyor (MGS), Mars Odyssey (ODY), and Mars Reconnaissance Orbiter (MRO) missions have enabled NASA to conduct reconnaissance and exploration of Mars from orbit for sixteen consecutive years. These radio systems on these spacecraft enabled radio science in orbit around Mars to improve the knowledge of the static structure of the Martian gravitational field. The continuity of the radio tracking data, which cover more than a solar cycle, also provides useful information to characterize the temporal variability of the gravity field, relevant to the planet's internal dynamics and the structure and dynamics of the atmosphere [1]. MGS operated for more than 7 years, between 1999 and 2006, in a frozen sun-synchronous, near-circular, polar orbit with the periapsis at approximately 370 km altitude. ODY and MRO have been orbiting Mars in two separate sun-synchronous orbits at different local times and altitudes. ODY began its mapping phase in 2002 with the periapis at approximately 390 km altitude and 4-5pm Local Solar Time (LST), whereas the MRO science mission started in November 2006 with the periapis at approximately 255 km altitude and 3pm LST. The 16 years of radio tracking data provide useful information on the atmospheric density in the Martian upper atmosphere. We used ODY and MRO radio data to recover the long-term periodicity of the major atmospheric constituents -- CO2, O, and He -- at the orbit altitudes of these two spacecraft [2]. The improved atmospheric model provides a better prediction of the annual and semi-annual variability of the dominant species. Therefore, the inclusion of the recovered model leads to improved orbit determination and an improved gravity field model of Mars with MGS, ODY, and MRO radio tracking data.

  18. On the possibility of life on early Mars

    Science.gov (United States)

    Oberbeck, V. R.; Fogleman, G.

    1990-01-01

    Prebiotic reactants, liquid water, and temperatures low enough for organic compounds to be stable are requirements for the origination of life as we know it. Prebiotic reactants and sufficiently low temperatures were present on Mars before liquid water vanished. Early in this time period, however, large planetesimal impacts may have periodically sterilized Mars, pyrolyzed organic compounds, and interrupted chemical origination of life. However, the calculated time interval between such impacts on Mars was larger just before liquid water vanished 3.8 Gyr (billion years) ago than it was on earth just before life originated. Therefore, there should have been sufficient time for life to originate on Mars. Ideal sites to search for microfossils are in the heavily cratered terrain of Upper Noachian age. Craters and channels in this terrain may have been the sites of ancient lakes and streams that could have provided habitats for the first microorganisms.

  19. Mars' core and magnetism.

    Science.gov (United States)

    Stevenson, D J

    2001-07-12

    The detection of strongly magnetized ancient crust on Mars is one of the most surprising outcomes of recent Mars exploration, and provides important insight about the history and nature of the martian core. The iron-rich core probably formed during the hot accretion of Mars approximately 4.5 billion years ago and subsequently cooled at a rate dictated by the overlying mantle. A core dynamo operated much like Earth's current dynamo, but was probably limited in duration to several hundred million years. The early demise of the dynamo could have arisen through a change in the cooling rate of the mantle, or even a switch in convective style that led to mantle heating. Presently, Mars probably has a liquid, conductive outer core and might have a solid inner core like Earth.

  20. Mars Technology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA’s Mars Exploration Program (MEP) calls for a series of highly ambitious missions over the next decade and beyond. The overall goals of the MEP must be...

  1. Mars Rover Photos API

    Data.gov (United States)

    National Aeronautics and Space Administration — This API is designed to collect image data gathered by NASA's Curiosity, Opportunity, and Spirit rovers on Mars and make it more easily available to other...

  2. Internal constitution of Mars.

    Science.gov (United States)

    Anderson, D. L.

    1972-01-01

    Models of the internal structure of Mars consistent with the mass, radius and moment of inertia of the planet are constructed. The models assume that the radius of the core is between 0.36 and 0.60 of the radius of the planet, that the zero-pressure density of the mantle is between 3.54 and 3.49 g/cu cm, and that the planet contains 25 to 28% iron. Meteorite models of Mars containing 25 wt % iron and 12 wt % core are also proposed. It is maintained that Mars in contrast to the earth is an incompletely differentiated planet with a core substantially richer in sulfur than the core of the earth. The absence of a magnetic field on Mars is possibly linked with lack of lunar precessional torque and the small size and high resistivity of the Martian core.

  3. Applications of Surface Penetrating Radar for Mars Exploration

    Science.gov (United States)

    Li, H.; Li, C.; Ran, S.; Feng, J.; Zuo, W.

    2015-12-01

    Surface Penetrating Radar (SPR) is a geophysical method that uses electromagnetic field probe the interior structure and lithological variations of a lossy dielectric materials, it performs quite well in dry, icy and shallow-soil environments. The first radar sounding of the subsurface of planet was carried out by Apollo Lunar Sounder Experiment (ALSE) of the Apollo 17 in 1972. ALSE provided very precise information about the moon's topography and revealed structures beneath the surface in both Mare Crisium and Mare Serenitatis. Russian Mars'92 was the first Mars exploration mission that tried to use SPR to explore martian surface, subsurface and ionosphere. Although Mars'96 launch failed in 1996, Russia(Mars'98, cancelled in 1998; Phobos-Grunt, launch failed in 2011), ESA(Mars Express, succeeded in 2003; Netlander, cancelled in 2003; ExoMars 2018) and NASA(MRO, succeeded in 2005; MARS 2020) have been making great effects to send SPR to Mars, trying to search for the existence of groundwater and life in the past 20 years. So far, no Ground Penetrating Radar(GPR) has yet provided in situ observations on the surface of Mars. In December 2013, China's CE-3 lunar rover (Yuto) equipped with a GPR made the first direct measurement of the structure and depth of the lunar soil, and investigation of the lunar crust structure along the rover path. China's Mars Exploration Program also plans to carry the orbiting radar sounder and rover GPR to characterize the nature of subsurface water or ices and the layered structure of shallow subsurface of Mars. SPR can provide diversity of applications for Mars exploration , that are: to map the distribution of solid and liquid water in the upper portions of the Mars' crust; to characterize the subsurface geologic environment; to investigate the planet's subsurface to better understand the evolution and habitability of Mars; to perform the martain ionosphere sounding. Based on SPR's history and achievements, combined with the

  4. A Mars 1984 mission

    Science.gov (United States)

    1977-01-01

    Mission objectives are developed for the next logical step in the investigation of the local physical and chemical environments and the search for organic compounds on Mars. The necessity of three vehicular elements: orbiter, penetrator, and rover for in situ investigations of atmospheric-lithospheric interactions is emphasized. A summary report and committee recommendations are included with the full report of the Mars Science Working Group.

  5. Mars Ice Age, Simulated

    Science.gov (United States)

    2003-01-01

    December 17, 2003This simulated view shows Mars as it might have appeared during the height of a possible ice age in geologically recent time.Of all Solar System planets, Mars has the climate most like that of Earth. Both are sensitive to small changes in orbit and tilt. During a period about 2.1 million to 400,000 years ago, increased tilt of Mars' rotational axis caused increased solar heating at the poles. A new study using observations from NASA's Mars Global Surveyor and Mars Odyssey orbiters concludes that this polar warming caused mobilization of water vapor and dust into the atmosphere, and buildup of a surface deposit of ice and dust down to about 30 degrees latitude in both hemispheres. That is the equivalent of the southern Unites States or Saudi Arabia on Earth. Mars has been in an interglacial period characterized by less axial tilt for about the last 300,000 years. The ice-rich surface deposit has been degrading in the latitude zone of 30 degrees to 60 degrees as water-ice returns to the poles.In this illustration prepared for the December 18, 2003, cover of the journal Nature, the simulated surface deposit is superposed on a topography map based on altitude measurements by Global Surveyor and images from NASA's Viking orbiters of the 1970s.Mars Global Surveyor and Mars Odyssey are managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, for the NASA Office of Space Science, Washington.

  6. Status of MARS Code

    Energy Technology Data Exchange (ETDEWEB)

    N.V. Mokhov

    2003-04-09

    Status and recent developments of the MARS 14 Monte Carlo code system for simulation of hadronic and electromagnetic cascades in shielding, accelerator and detector components in the energy range from a fraction of an electronvolt up to 100 TeV are described. these include physics models both in strong and electromagnetic interaction sectors, variance reduction techniques, residual dose, geometry, tracking, histograming. MAD-MARS Beam Line Build and Graphical-User Interface.

  7. Why exobiology on Mars?

    Science.gov (United States)

    Brack, A.

    1996-11-01

    Processing of organic molecules by liquid water was probably an essential requirement towards the emergence of terrestrial primitive life. According to Oparin's hypothesis, organic building blocks required for early life were produced from simple organic molecules formed in a primitive reducing atmosphere. Geochemists favour now a less reducing atmosphere dominated by carbon dioxide. In such an atmosphere very few building blocks are formed. Import of extra-terrestrial organic molecules may represent an alternative supply. Experimental support for such an alternative scenario is examined in comets, meteorites and micrometeorites. The early histories of Mars and Earth clearly show similarities. Liquid water was once stable on the surface of Mars attesting the presence of an atmosphere capable of deccelerating C-rich micrometeorites. Therefore, primitive life may have developed on Mars as well. Liquid water disappeared from the surface of Mars very early, about 3.8 Ga ago. The Viking missions did not find, at the surface of the Martian soil, any organic molecules or clear-cut evidence for microbial activities such as photo-synthesis, respiration or nutrition. The results can be explained referring to an active photochemistry of Martian soil driven by the high influx of solar UV. These experiments do not exclude the existence of organic molecules and fossils of micro-organisms which developed on early Mars until liquid water disappeared. Mars may store below its surface some well preserved clues of a still hypothetical primitive life.

  8. Mars Rover RTG Study

    Energy Technology Data Exchange (ETDEWEB)

    Schock, Alfred

    1989-11-27

    This report summarizes the results of a Radioisotope Thermoelectric Generator (RTG) design study conducted by Fairchild Space Company at the direction of the U.S. Department of Energy's Office of Special Applications, in support of the Mars Rover and Sample Return mission under investigation at NASA's Jet Propulsion Laboratory. Presented at the 40th Congress of the IAF, Oct. 7-13, 1989 in Torremolinos, Malaga-Spain. The paper describes the design and analysis of Radioisotope Thermoelectric Generators (RTGs) for powering the Mars Rover vehicle, which is a critical element of the unmanned Mars Rover and Sample Return mission (MRSR). The RTG design study was conducted by Fairchild Space for the U.S. DOE in support of the JPL MRSR Project. The paper briefly describes a reference mission scenario, an illustrative Rover design and activity pattern on Mars, and its power system requirements and environmental constraints, including the RTG cooling requirements during transit to Mars. It summarizes the baseline RTG's mass breakdown, and presents a detailed description of its thermal, thermoelectric, and electrical analysis. The results presented show the RTG performance achievable with current technology, and the performance improvements that would be achievable with various technology developments. It provides a basis for selecting the optimum strategy for meeting the Mars Rover design goals with minimal programmatic risk and cost. Cross Reference CID #7135 dated 10/1989. There is a duplicate copy. This document is not relevant to the OSTI Library. Do not send.

  9. Clouds over Mars!

    Science.gov (United States)

    1997-01-01

    This is the first color image ever taken from the surface of Mars of an overcast sky. Featured are pink stratus clouds coming from the northeast at about 15 miles per hour (6.7 meters/second) at an approximate height of ten miles (16 kilometers) above the surface. The clouds consist of water ice condensed on reddish dust particles suspended in the atmosphere. Clouds on Mars are sometimes localized and can sometimes cover entire regions, but have not yet been observed to cover the entire planet. The image was taken about an hour and forty minutes before sunrise by the Imager for Mars Pathfinder (IMP) on Sol 16 at about ten degrees up from the eastern Martian horizon.Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages and Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  10. The MARS2013 Mars analog mission.

    Science.gov (United States)

    Groemer, Gernot; Soucek, Alexander; Frischauf, Norbert; Stumptner, Willibald; Ragonig, Christoph; Sams, Sebastian; Bartenstein, Thomas; Häuplik-Meusburger, Sandra; Petrova, Polina; Evetts, Simon; Sivenesan, Chan; Bothe, Claudia; Boyd, Andrea; Dinkelaker, Aline; Dissertori, Markus; Fasching, David; Fischer, Monika; Föger, Daniel; Foresta, Luca; Fritsch, Lukas; Fuchs, Harald; Gautsch, Christoph; Gerard, Stephan; Goetzloff, Linda; Gołebiowska, Izabella; Gorur, Paavan; Groemer, Gerhard; Groll, Petra; Haider, Christian; Haider, Olivia; Hauth, Eva; Hauth, Stefan; Hettrich, Sebastian; Jais, Wolfgang; Jones, Natalie; Taj-Eddine, Kamal; Karl, Alexander; Kauerhoff, Tilo; Khan, Muhammad Shadab; Kjeldsen, Andreas; Klauck, Jan; Losiak, Anna; Luger, Markus; Luger, Thomas; Luger, Ulrich; McArthur, Jane; Moser, Linda; Neuner, Julia; Orgel, Csilla; Ori, Gian Gabriele; Paternesi, Roberta; Peschier, Jarno; Pfeil, Isabella; Prock, Silvia; Radinger, Josef; Ramirez, Barbara; Ramo, Wissam; Rampey, Mike; Sams, Arnold; Sams, Elisabeth; Sandu, Oana; Sans, Alejandra; Sansone, Petra; Scheer, Daniela; Schildhammer, Daniel; Scornet, Quentin; Sejkora, Nina; Stadler, Andrea; Stummer, Florian; Taraba, Michael; Tlustos, Reinhard; Toferer, Ernst; Turetschek, Thomas; Winter, Egon; Zanella-Kux, Katja

    2014-05-01

    We report on the MARS2013 mission, a 4-week Mars analog field test in the northern Sahara. Nineteen experiments were conducted by a field crew in Morocco under simulated martian surface exploration conditions, supervised by a Mission Support Center in Innsbruck, Austria. A Remote Science Support team analyzed field data in near real time, providing planning input for the management of a complex system of field assets; two advanced space suit simulators, four robotic vehicles, an emergency shelter, and a stationary sensor platform in a realistic work flow were coordinated by a Flight Control Team. A dedicated flight planning group, external control centers for rover tele-operations, and a biomedical monitoring team supported the field operations. A 10 min satellite communication delay and other limitations pertinent to human planetary surface activities were introduced. The fields of research for the experiments were geology, human factors, astrobiology, robotics, tele-science, exploration, and operations research. This paper provides an overview of the geological context and environmental conditions of the test site and the mission architecture, in particular the communication infrastructure emulating the signal travel time between Earth and Mars. We report on the operational work flows and the experiments conducted, including a deployable shelter prototype for multiple-day extravehicular activities and contingency situations.

  11. A Simulation Study of the Thermosphere Mass Density Response to Substorms Using GITM Model

    Science.gov (United States)

    Liu, X.; Ridley, A. J.

    2014-12-01

    The temporal and spatial variations of the thermosphere mass density during a variety of idealized substorms were investigated using the Global Ionosphere Thermosphere Model (GITM) simulation and Challenging Minisatellite Payload (CHAMP) satellite. From the GITM simulation, the maximum mass density perturbation of an idealized substorm with a peak variation of Hemispheric Power (HP) Index of 50 GW and interplanetary magnetic field (IMF) Bz of -2 nT was ~14% about 50 min after the substorm onset in the nightside sector of the aurora zone. About 110 min after onset, a negative mass density perturbation (~-5%) occurred in the night sector, which was consistent with the mass density measurement of the CHAMP satellite. Further investigation suggests that a large scale in situ gravity wave was generated in the aurora zone and propagated to the mid and low latitudes. Simulations with IMF Bz changes, with HP being constant and HP changing and IMF Bz being constant were run to investigate any nonlinearities in the combined response. The mass density perturbation due the IMF Bz variation peaks in the dusk sector and the density perturbation due to HP input peaks in the nightside sector. The non-linear of the mass density response to different energy input is less than 6%. The thermospheric mass density at higher altitudes is more sensitive to the Joule heating energy input. The change in hemisphere power adds electron density to lower altitudes, so the heating due to the HP change is at lower altitudes than the heating due to the IMF Bz change. This causes the density change due to the HP change to be larger than the density change due to the IMF change.

  12. A two-dimensional global simulation study of inductive-dynamic magnetosphere-ionosphere/thermosphere coupling

    Science.gov (United States)

    Tu, J.; Song, P.

    2016-12-01

    We have developed a new numerical simulation model of the ionosphere/thermosphere by using an inductive-dynamic approach (including self-consistent solutions of Faraday's law and retaining inertia terms in ion momentum equations), that is, based on magnetic field B and plasma velocity v (B, v paradigm), which is distinctive from the conventional modeling based on electric field E and current j. The model solves self-consistently time-dependent continuity, momentum, and energy equations for multiple species of ions and neutrals including photochemistry, and Maxwell's equations. The governing equations solved in the model are a set of multifluid-collisional-Hall MHD equations which are one of unique features of our ionosphere/thermosphere model. With such an inductive-dynamic approach, not only sound wave mode but also all possible MHD wave modes are retained in the solutions of the governing equations so that the dynamic coupling between the magnetosphere and ionosphere and among different regions of the ionosphere can be self-consistently investigated. In the present study, we demonstrate dynamic propagation of field-aligned currents and ionospheric electric field carried by Alfven waves, as well as formation of closure horizontal currents (Pedersen currents in the E-region), indicating that the M-I coupling is via the Alfven waves instead of the field-aligned currents or electric field mapping. The simulation results also show that the Poynting flux and strongest energy dissipation in the ionosphere/thermosphere is in the regions of the largest ion velocities and not necessarily in the auroral oval where the field-aligned currents reside. The frictional heating increases plasma temperature and thus drives ion upflows. The frictional heating also increase neutral temperature and produces neutral upflows but in a much longer time scale. Furthermore, the coupling of high-to-low latitude ionosphere is investigated in terms of propagation of fast MHD waves.

  13. Comparison of high-latitude thermospheric meridional winds II: combined FPI, radar and model climatologies

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, E.M.; Aruliah, A.; Mueller-Wodarg, I.C.F.; Aylward, A. [Atmospheric Physics Lab., Univ. Coll. London, London (United Kingdom)

    2004-07-01

    The climatological behaviour of the thermospheric meridional wind above Kiruna, Sweden (67.4 N, 20.4 E) has been investigated for seasonal and solar cycle dependence using six different techniques, comprising both model and experimental sources. Model output from both the empirical Horizontal Wind Model (HWM) (Hedin et al., 1988) and the numerical coupled thermosphere and ionosphere model (CTIM) are compared to the measured behaviour at kiruna, as a single site example. The empirical International Reference Ionosphere (IRI) model is used as input to an implementation of servo theory, to provide another climatology combining empirical input with a theoretical framework. The experimental techniques have been introduced in a companion paper in this issue and provide climatologies from direct measurements, using fabry-perot interferometers (FPI), together with 2 separate techniques applied to the European incoherent scatter radar (EISCAT) database to derive neutral winds. One of these techniques uses the same implementation of servo theory as has been used with the IRI model. Detailed comparisons for each season and solar activity category allow for conclusions to be drawn as to the major influences on the climatological behaviour of the wind at this latitude. Comparison of the incoherent scatter radar (ISR) derived neutral winds with FPI, empirical model and numerical model winds is important to our understanding and judgement of the validity of the techniques used to derive thermospheric wind databases. The comparisons also test model performance and indicate possible reasons for differences found between the models. In turn, the conclusions point to possible improvements in their formulation. In particular it is found that the empirical models are over-reliant on mid-latitude data in their formulation, and fail to provide accurate estimates of the winds at high-latitudes. (orig.)

  14. Intradiurnal wind variations observed in the lower thermosphere over the South Pole

    Directory of Open Access Journals (Sweden)

    Y. I. Portnyagin

    Full Text Available The first meteor radar measurements of meridional winds in the lower thermosphere (about 95 ± 5 km, along four azimuth directions: 0°, 90°E, 180° and 90°W; approximately 2° from the geographic South Pole were made during two observational campaigns: January 19, 1995-January 26, 1996, and November 21, 1996-January 27, 1997. Herein we report analyses of the measurement results, obtained during the first campaign, which cover the whole one-year period, with particular emphasis on the transient nature and seasonal behavior of the main parameters of the intradiurnal wind oscillations. To analyze the data, two complementary methods are used: the well-known periodogram (FFT technique and the S-transform technique. The most characteristic periods of the intradiurnal oscillations are found to be rather uniformly spread between about 7 h and 12 h. All of these oscillations are westward-propagating with zonal wave number s=1 and their usual duration is confined to several periods. During the austral winter season the oscillations with periods less than 12 h are the most intensive, while during summer season the 12-h oscillations dominate. Lamb waves and internal-gravity wave propagation, non-linear interaction of the short-period tides, excitation in situ of the short period waves may be considered as possible processes which are responsible for intradiurnal wind oscillations in the lower thermosphere over South Pole.

    Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides

  15. Measurements of Ion Drifts and Thermospheric Neutral Winds at the Jicamarca Radio Observatory

    Science.gov (United States)

    Meriwether, J. W.; Navarro, L.; Chau, J. L.; Fejer, B. G.

    2010-12-01

    Measurements of ion drifts and thermospheric neutral winds obtained simultaneously with zonal and vertical ion drift measurements of F-region plasma have been made at the Jicamarca Radio Observatory at different times during the year since August, 2009. This period is coincident with an anomalous period of extremely low solar activity. For campaigns taking place in September, 2009, March, 2010, and September, 2010, the Jicamarca 50 MHz radar operated to measure both vertical ion drifts and horizontal neutral winds from 200 to 800 km. The Jicamarca Fabry-Perot interferometer (FPI) was installed in August, 2009, and measurements have been ongoing since first light on 15 August, 2010. The FPI instrument is located in an observatory installed on a hill overlooking the Jicamarca valley and located above the cloud inversion layer, which improved the chances of observing during local summer. This instrument after an upgrade in August 2010 is able to make zonal and meridional thermospheric wind and temperature measurements with an accuracy of 5 to 10 ms-1 and 15 to 30 K. Also obtained during the measurement campaigns with the JRO radar facility were simultaneous measurements of thermospheric winds from the FPI observatory located in Arequipa, Peru, which is located 4 degrees latitude to the south of Jicamarca. The results obtained generally showed good agreement between the observed neutral winds and ion drifts. The vertical variation of the ion drifts is significant from the early evening twilight period to midnight suggesting that the transition from the E-region dynamo to the F-region dynamo takes place rather slowly as compared with more active solar flux periods.

  16. Equatorial thermospheric wind changes during the solar cycle: Measurements at Arequipa, Peru, from 1983 to 1990

    Energy Technology Data Exchange (ETDEWEB)

    Biondi, M.A. (Univ. of Pittsburgh, PA (United States)); Meriwether, J.W. Jr. (Air Force Geophysics Lab., Hanscom AFB, MA (United States)); Fejer, B.G.; Gonzalez, S.A. (Utah State Univ., Logan (United States)); Hallenbeck, D.C. (NASA Laser Tracking Station, Arequipa (Peru))

    1991-09-01

    Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630-nm emission line have been used to determine near-equatorial thermospheric wind velocities at Arequipa, Peru, over {approximately} 2/3 of a solar cycle. Monthly-average nocturnal variations in the meridional and zonal wind components were calculated from the nightly data to remove short term (day-to-day) variability, facilitating display of seasonal changes in the wind patterns, as well as any additional changes introduced by the progression of the solar cycle. The measured seasonal variations in the wind patterns are more pronounced than the solar cycle variations and are more readily understandable in terms of the expected, underlying forcing and damping processes. For most of the years, at the winter solstice, there is a weak ({le} 100 m/s) transequatorial flow from the summer to the winter hemisphere in the early and the late night, with essentially zero velocities in between. At the equinoxes, an early-night poleward (southward) flow at solar minimum (1986) is replaced by an equatorward (northward) flow at solar maximum (1989-1990). The zonal flows are predominantly eastward throughout the night, except for the solar minimum equinoxes, where brief westward flows appear in the early and the late night. The peak eastward velocities increase toward solar maximum; at the winter solstice, they are {approximately} 100-130 m/s in 1983, 1984 and 1986, reaching {approximately} 200 m/s in 1988, 1989 and 1990. The present equatorial thermospheric wind determinations agree in some respects with the satellite-data-based horizontal wind model IIWM-87 and the vector spherical harmonic form of the thermospheric general circulation model.

  17. Effects of various solar indices on accuracy of Earth’s thermospheric neutral density models

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Four kinds of solar indices F10.7, E10.7, S10, Mg10 and four thermospheric neutral density models, i.e., CIRA72, DTM94, NRLMSISE00 and JB2006, are discussed. The CHAMP accelerometer data are used to calculate thermospheric total mass density. Based on the comparison of the model densities with CHAMP observations, the effects of various indices on the model accuracy are detected. It is found that under quiet and moderate solar conditions (F10.7<160), all of the models’ errors are reduced about 15% by using E10.7 instead of F10.7, while under active solar conditions (F10.7>200) the error’s standard deviation using E10.7 increases quickly and causes the models’ accuracy to fall down. With regard to S10, Mg10, their effects under quiet solar conditions are inconspicuous. If under active solar conditions, they can reduce the model error’s standard deviation by 5%-10%, implying that S10, Mg10 make the model error more stable. The JB2006 model, which was constructed by multi-solar-index (F10.7, S10, Mg10), is compared with DTM94 and NRLMSISE00 based on single-solar-index. It is found that JB2006’s accuracy is better than DTM94’s, and is close to NRLMSISE00 under the quiet solar condition. During the solar burst occurring on October 26, 2003, JB2006 has been in best agreement with CHAMP observations. All in all, the new indices may improve thermospheric density models’ accuracy under some special conditions. Concretely, E10.7 may reduce the average error of models and S10, Mg10 may prevent the error’s divergence.

  18. Mars at Ls 357o

    Science.gov (United States)

    2006-01-01

    31 January 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 357o during a previous Mars year. This month, Mars looks similar, as Ls 357o occurred in mid-January 2006. The picture shows the south polar region of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Winter/Southern Summer

  19. Mars at Ls 324o

    Science.gov (United States)

    2005-01-01

    29 November 2005 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 324o during a previous Mars year. This month, Mars looks similar, as Ls 324o occurred in mid-November 2005. The picture shows the south polar region of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Winter/Southern Summer

  20. Numerical modeling study of the momentum deposition of small amplitude gravity waves in the thermosphere

    Directory of Open Access Journals (Sweden)

    X. Liu

    2013-01-01

    Full Text Available We study the momentum deposition in the thermosphere from the dissipation of small amplitude gravity waves (GWs within a wave packet using a fully nonlinear two-dimensional compressible numerical model. The model solves the nonlinear propagation and dissipation of a GW packet from the stratosphere into the thermosphere with realistic molecular viscosity and thermal diffusivity for various Prandtl numbers. The numerical simulations are performed for GW packets with initial vertical wavelengths (λz ranging from 5 to 50 km. We show that λz decreases in time as a GW packet dissipates in the thermosphere, in agreement with the ray trace results of Vadas and Fritts (2005 (VF05. We also find good agreement for the peak height of the momentum flux (zdiss between our simulations and VF05 for GWs with initial λz ≤ 2π H in an isothermal, windless background, where H is the density scale height. We also confirm that zdiss increases with increasing Prandtl number. We include eddy diffusion in the model, and find that the momentum deposition occurs at lower altitudes and has two separate peaks for GW packets with small initial λz. We also simulate GW packets in a non-isothermal atmosphere. The net λz profile is a competition between its decrease from viscosity and its increase from the increasing background temperature. We find that the wave packet disperses more in the non-isothermal atmosphere, and causes changes to the momentum flux and λz spectra at both early and late times for GW packets with initial λz ≥ 10 km. These effects are caused by the increase in T in the thermosphere, and the decrease in T near the mesopause.

  1. Thermospheric Diagnostics Using in situ Probing by Electron-Beam-Induced Luminescence.

    Science.gov (United States)

    1980-01-30

    DITIB TO ST TE EN (o he eot ARoed fe( eor pulcrlae1itrbto 5niie I. SPEOMENT RARYNIZOTS EADADE 0 RGA LMET RJC.TS U ta. EY W St (Continue onr itey e side...to an understanding of a number of high-altitude phenomena which include: (i) the production of 4.3-um CO2 radiation in the lower thermosphere...atmospheric conditions. Cooling of N 2* by CO2 is expected to be competitive with cooling by O(3P) at altitudes Z110 km, and diffusion is expected to

  2. MAVEN Observations of Atmospheric Loss at Mars

    Science.gov (United States)

    Curry, Shannon; Luhmann, Janet; Jakosky, Bruce M.; Brain, David; LeBlanc, Francis; Modolo, Ronan; Halekas, Jasper S.; Schneider, Nicholas M.; Deighan, Justin; McFadden, James; Espley, Jared R.; Mitchell, David L.; Connerney, J. E. P.; Dong, Yaxue; Dong, Chuanfei; Ma, Yingjuan; Cohen, Ofer; Fränz, Markus; Holmström, Mats; Ramstad, Robin; Hara, Takuya; Lillis, Robert J.

    2016-06-01

    The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has been making observations of the Martian upper atmosphere and its escape to space since November 2014. The subject of atmospheric loss at terrestrial planets is a subject of intense interest not only because of the implications for past and present water reservoirs, but also for its impacts on the habitability of a planet. Atmospheric escape may have been especially effective at Mars, relative to Earth or Venus, due to its smaller size as well as the lack of a global dynamo magnetic field. Not only is the atmosphere less gravitationally bound, but also the lack of global magnetic field allows the impinging solar wind to interact directly with the Martian atmosphere. When the upper atmosphere is exposed to the solar wind, planetary neutrals can be ionized and 'picked up' by the solar wind and swept away.Both neutral and ion escape have played significant roles the long term climate change of Mars, and the MAVEN mission was designed to directly measure both escaping planetary neutrals and ions with high energy, mass, and time resolution. We will present 1.5 years of observations of atmospheric loss at Mars over a variety of solar and solar wind conditions, including extreme space weather events. We will report the average ion escape rate and the spatial distribution of escaping ions as measured by MAVEN and place them in context both with previous measurements of ion loss by other spacecraft (e.g. Phobos 2 and Mars Express) and with estimates of neutral escape rates by MAVEN. We will then report on the measured variability in ion escape rates with different drivers (e.g. solar EUV, solar wind pressure, etc.) and the implications for the total ion escape from Mars over time. Additionally, we will also discuss the implications for atmospheric escape at exoplanets, particularly weakly magnetized planetary bodies orbiting M-dwarfs, and the dominant escape mechanisms that may drive atmospheric erosion in other

  3. Guidelines for 2008 MARS exercise

    CERN Multimedia

    HR Department

    2008-01-01

    Full details of the Merit Appraisal and Recognition Scheme (MARS) are available via the HR Department’s homepage or directly on the Department’s MARS web page: https://cern.ch/hr-dept/ https://cern.ch/hr-eguide/mars/mars.asp You will find on these pages: MARS procedures including the MARS timetable for proposals and decisions; Regulations with links to the scheme’s statutory basis; Frequently Asked Questions; Useful documents with links to relevant documentation; e.g. mandate of the Senior Staff Advisory Committee (SSAC); Related links and contacts. HR Department Tel. 73566

  4. Divesidad y distribución de los crustáceos decápodos de la franja superior del talud superior continental (300-500 m. de profundidad en la parte norte del mar Caribe colombiano Diversity and distribution of the crustacean decapods of the upper continental slope (300-500m deep in the nort colombian Caribeanean sea

    Directory of Open Access Journals (Sweden)

    Campos Campos Néstor Hernando

    2000-06-01

    de los ejemplares se concentró en 5 familias. No seencontraron grupos de estaciones ubicadas frente a las ecoregiones seleccionadas, lo cual sugiereque en la parte norte del talud superior contienetal del Mar Caribe colombiano se presentauna fauna de decápodos homogénea, y que las características que sirven para definir y separarlas ecoregiones a nivel costero no influyen en la parte superior del talud continental lo suficientecomo para determinar los ensamblajes de crustáceos decápodos. Se establecieron dos gruposde crustáceos decápodos: Uno a 300 y el otro a 500 m de profundidad. El primero presentó unamayor abundancia y riqueza. No se encontraron diferencias entre la diversidad, dominanciay equitatividad entre los dos grupos. El grupo de 300 m de profundidad fue definido por lasespecies Portunus spinicarpus, Methanephrops binghami, Munida longipesy Penaeopsis serrata. El grupode 500 m fue definido por las especies Glyphocrangon neglecta, Pleoticus robustusy Munidopsis riveroi.The Instituto de investigaciones Marinas y Costeras INVEMAR, developed the proyect about thecaracterization of the macrofauna of the upper continental slope of the Colombian Caribeansea. The present proyect covered the identification, distribution, abundance and faunisticalcomposition of the crustacean decapods, of the north of Colombian Caribean sea, between LaGuajira and Magdalena, to 300 and 500m deep. The material was placed in the Colección deReferencia de Organismos Marinos of INVEMAR and the Museo de Historia Natural delInstituto de Ciencias Naturales de la Universidad Nacional de Colombia. The taxonomicinformation about each species was fed the data base about marine biodiversity of theINVEMAR. 6381 individuals of the crustacean decapods were collected and 99 species, 48 ofwhom are the firts report for the species in the Colombian Caribean sea and, two are newspecies. One of the genus Cymonomoidesand the other of the genus Pyromaia. Five families werethe most abundant 77

  5. Degradation of Victoria Crater, Mars

    Science.gov (United States)

    Wilson, Sharon A.; Grant, John A.; Cohen, Barbara A.; Golombek, Mathew P.; Geissler, Paul E.; Sullivan, Robert J.; Kirk, Randolph L.; Parker, Timothy J.

    2008-01-01

    The $\\sim$750 m diameter and $\\sim$75 m deep Victoria crater in Meridiani Planum, Mars, presents evidence for significant degradation including a low, serrated, raised rim characterized by alternating alcoves and promontories, a surrounding low relief annulus, and a floor partially covered by dunes. The amount and processes of degradation responsible for the modified appearance of Victoria crater were evaluated using images obtained in situ by the Mars Exploration Rover Opportunity in concert with a digital elevation model created using orbital HiRISE images. Opportunity traversed along the north and northwest rim and annulus, but sufficiently characterized features visible in the DEM to enable detailed measurements of rim relief, ejecta thickness, and wall slopes around the entire degraded, primary impact structure. Victoria retains a 5 m raised rim consisting of 1-2 m of uplifted rocks overlain by 3 m of ejecta at the rim crest. The rim is $\\sim$120 to 220 m wide and is surrounded by a dark annulus reaching an average of 590 m beyond the raised rim. Comparison between observed morphology and that expected for pristine craters 500 to 750 m across indicate the original, pristine crater was close to 600 m in diameter. Hence, the crater has been erosionally widened by approximately 150 m and infilled by about 50 m of sediments. Eolian processes are responsible for modification at Victoria, but lesser contributions from mass wasting or other processes cannot be ruled out. Erosion by prevailing winds is most significant along the exposed rim and upper walls and accounts for $\\sim$50 m widening across a WNW-ESE diameter. The volume of material eroded from the crater walls and rim is $\\sim$20% less than the volume of sediments partially filling the crater, indicating eolian infilling from sources outside the crater over time. The annulus formed when $\\sim$1 m deflation of the ejecta created a lag of more resistant hematite spherules that trapped darker, regional

  6. Vacuum ultraviolet instrumentation for solar irradiance and thermospheric airglow

    Science.gov (United States)

    Woods, Thomas N.; Rottman, Gary J.; Bailey, Scott M.; Solomon, Stanley C.

    1993-01-01

    A NASA sounding rocket experiment was developed to study the solar extreme ultraviolet (EUV) spectral irradiance and its effect on the upper atmosphere. Both the solar flux and the terrestrial molecular nitrogen via the Lyman-Birge-Hopfield bands in the far ultraviolet (FUV) were measured remotely from a sounding rocket on October 27, 1992. The rocket experiment also includes EUV instruments from Boston University (Supriya Chakrabarti), but only the National Center for Atmospheric Research (NCAR)/University of Colorado (CU) four solar instruments and one airglow instrument are discussed here. The primary solar EUV instrument is a 1/4 meter Rowland circle EUV spectrograph which has flown on three rockets since 1988 measuring the solar spectral irradiance from 30 to 110 nm with 0.2 nm resolution. Another solar irradiance instrument is an array of six silicon XUV photodiodes, each having different metallic filters coated directly on the photodiodes. This photodiode system provides a spectral coverage from 0.1 to 80 nm with about 15 nm resolution. The other solar irradiance instrument is a silicon avalanche photodiode coupled with pulse height analyzer electronics. This avalanche photodiode package measures the XUV photon energy providing a solar spectrum from 50 to 12,400 eV (25 to 0.1 nm) with an energy resolution of about 50 eV. The fourth solar instrument is an XUV imager that images the sun at 17.5 nm with a spatial resolution of 20 arc-seconds. The airglow spectrograph measures the terrestrial FUV airglow emissions along the horizon from 125 to 160 nm with 0.2 nm spectral resolution. The photon-counting CODACON detectors are used for three of these instruments and consist of coded arrays of anodes behind microchannel plates. The one-dimensional and two-dimensional CODACON detectors were developed at CU by Dr. George Lawrence. The pre-flight and post-flight photometric calibrations were performed at our calibration laboratory and at the Synchrotron Ultraviolet

  7. Mars Rover RTG Study

    Energy Technology Data Exchange (ETDEWEB)

    Schock, Alfred

    1989-10-01

    Presented at the 40th Congress of the IAF, Oct. 7-13, 1989 in Torremolinos, Malaga-Spain. The paper describes the design and analysis of Radioisotope Thermoelectric Generators (RTGs) for powering the Mars Rover vehicle, which is a critical element of the unmanned Mars Rover and Sample Return mission (MRSR). The RTG design study was conducted by Fairchild Space for the U.S. DOE in support of the JPL MRSR Project. The paper briefly describes a reference mission scenario, an illustrative Rover design and activity pattern on Mars, and its power system requirements and environmental constraints, including the RTG cooling requirements during transit to Mars. It summarizes the baseline RTG's mass breakdown, and presents a detailed description of its thermal, thermoelectric, and electrical analysis. The results presented show the RTG performance achievable with current technology, and the performance improvements that would be achievable with various technology developments. It provides a basis for selecting the optimum strategy for meeting the Mars Rover design goals with minimal programmatic risk and cost. There is a duplicate copy and three copies in the file.

  8. The Mars Plasma Environment

    CERN Document Server

    Russell, C. T

    2007-01-01

    Mars sits very exposed to the solar wind and, because it is a small planet, has but a weak hold on its atmosphere. The solar wind therefore plays an important role in the evolution of the martian atmosphere. Over the last four decades a series of European missions, first from the Soviet Union and more recently from the European Space Agency, together with a single investigation from the U.S., the Mars Global Surveyor spacecraft, have added immeasurably to our understanding of the interplay between the solar wind and Mars atmosphere. Most recently the measurements of the plasma and fast neutral populations, conducted on the Mars Express spacecraft by the ASPERA-3 instrument have been acquired and analyzed. Their presentation to the public, most notably at the workshop "The Solar Wind Interaction and Atmosphere Evolution of Mars" held in Kiruna in early 2006, was the inspiration for this series of articles. However participation in the Kiruna conference was not a selection criterion for this volume. The papers ...

  9. Pick-up Ion Sputtering of Mars' Atmosphere: Analysis of MAVEN Data and Simulations

    Science.gov (United States)

    Williamson, Hayley N.; Leclercq, Ludivine; Johnson, Robert E.; Curry, Shannon; Elrod, Meredith K.; Luhmann, Janet; Leblanc, Francois

    2016-10-01

    One of the ways hot oxygen escapes the exosphere of Mars is through sputtering caused by the precipitation of, primarily, O+ pickup ions. This process is thought to have been particularly important early in martian history, as it is correlated with increased solar activity (Luhmann 1992). With ion precipitation data from the MAVEN mission for a variety of solar conditions (Leblanc 2015), we can potentially see the effect of atmospheric sputtering. To determine if this process is apparent in MAVEN data, we first model the thermosphere and exosphere with an O and CO2 Direct Simulation Monte Carlo model. We then introduce a heat flux representative of the energy deposited by pickup ions for a variety solar conditions and look for the resulting signatures in the in situ neutral and ion atmospheric data from the NGIMS instrument available on the PDS. Preliminary simulations and data analysis are suggestive. Analysis of the simulations and the data analysis will be presented.

  10. Emerging pattern of global change in the upper atmosphere and ionosphere

    Directory of Open Access Journals (Sweden)

    J. Laštovička

    2008-05-01

    Full Text Available In the upper atmosphere, greenhouse gases produce a cooling effect, instead of a warming effect. Increases in greenhouse gas concentrations are expected to induce substantial changes in the mesosphere, thermosphere, and ionosphere, including a thermal contraction of these layers. In this article we construct for the first time a pattern of the observed long-term global change in the upper atmosphere, based on trend studies of various parameters. The picture we obtain is qualitative, and contains several gaps and a few discrepancies, but the overall pattern of observed long-term changes throughout the upper atmosphere is consistent with model predictions of the effect of greenhouse gas increases. Together with the large body of lower atmospheric trend research, our synthesis indicates that anthropogenic emissions of greenhouse gases are affecting the atmosphere at nearly all altitudes between ground and space.

  11. Case study of the mesospheric and lower thermospheric effects of solar X-ray flares: coupled ion-neutral modelling and comparison with EISCAT and riometer measurements

    Energy Technology Data Exchange (ETDEWEB)

    Enell, C.F.; Vierinen, J.P.; Kero, A.; Ulich, T.; Turunen, E. [Oulu Univ., Sodankylae (Finland). Sodankylae Geophysical Observatory; Verronen, P.T.; Seppaelae, A. [Finnish Meteorological Inst., Helsinki (Finland). Earth Observation unit; Beharrell, M.J.; Honary, F. [Lancaster Univ. (United Kingdom). Dept. of Communication Systems

    2008-07-01

    Two case studies of upper mesospheric and lower thermospheric (UMLT) high-latitude effects of solar X-ray flares are presented. SodankylaeIon-neutral Chemistry Model (SIC) electron density profiles agree with D-region EISCAT and riometer observations, provided that the profiles of the most variable ionisable component, nitric oxide, are adjusted to compensate for NO{sub x} production during preceding geomagnetically active periods. For the M6-class flare of 27 April 2006, following a quiet period, the agreement with cosmic noise absorption observed by the Sodankylaeriometers was within reasonable limits without adjustment of the [NO] profile. For the major (X17-class) event of 28 October 2003, following high auroral activity and solar proton events, the NO concentration had to be increased up to on the order of 10{sup 8} cm{sup -3} at the D-region minimum. Thus [NO] can in principle be measured by combining SIC with observations, if the solar spectral irradiance and particle precipitation are adequately known. As the two case events were short and modelled for high latitudes, the resulting neutral chemical changes are insignificant. However, changes in the model ion chemistry occur, including enhancements of water cluster ions. (orig.)

  12. Mars Spark Source Prototype

    Science.gov (United States)

    Eichenberg, Dennis J.; Lindamood, Glenn R.; Weiland, Karen J.; VanderWal, Randall L.

    1999-01-01

    The Mars Spark Source Prototype (MSSP) hardware has been developed as part of a proof of concept system for the detection of trace metals such as lead, cadmium, and arsenic in Martian dusts and soils. A spark discharge produces plasma from a soil sample and detectors measure the optical emission from metals in the plasma that will allow their identification and quantification. Trace metal measurements are vital for the assessment of the potential toxicity of the Martian environment for human exploration. The current method of X-ray fluorescence can yield concentrations only of major species. Other instruments are incompatible with the volume, weight, and power constraints for a Mars mission. The instrument will be developed primarily for use in the Martian environment, but would be adaptable for terrestrial use in environmental monitoring. This paper describes the Mars Spark Source Prototype hardware, the results of the characterization tests, and future plans for hardware development.

  13. Magnetic storms on Mars

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2011-01-01

    Based on data from the Mars Global Surveyor magnetometer we examine periods of significantly enhanced magnetic disturbances in the martian space environment. Using almost seven years of observations during the maximum and early declining phase of the previous solar cycle the occurrence pattern...... and typical time profile of such periods is investigated and compared to solar wind measurements at Earth. Typical durations of the events are 20–40h, and there is a tendency for large events to last longer, but a large spread in duration and intensity are found. The large and medium intensity events at Mars...... field disturbance at Mars is solar wind dynamic pressure variations associated with the eccentricity of the martian orbit around the Sun....

  14. Remanent magnetism at Mars

    Science.gov (United States)

    Curtis, S. A.; Ness, N. F.

    1988-01-01

    It is shown that a strong case can be made for an intrinsic magnetic field of dynamo origin for Mars earlier in its history. The typical equatorial magnetic field intensity would have been equal to about 0.01-0.1 gauss. The earlier dynamo activity is no longer extant, but a significant remanent magnetic field may exist. A highly non-dipole magnetic field could result from the remanent magnetization of the surface. Remanent magnetization may thus play an important role in the Mars solar wind interactions, in contrast to Venus with its surface temperatures above the Curie point. The anomalous characteristics of Mars'solar wind interaction compared to that of Venus may be explicable on this basis.

  15. VR for Mars Pathfinder

    Science.gov (United States)

    Blackmon, Theodore

    1998-01-01

    Virtual reality (VR) technology has played an integral role for Mars Pathfinder mission, operations Using an automated machine vision algorithm, the 3d topography of the Martian surface was rapidly recovered fro -a the stereo images captured. by the Tender camera to produce photo-realistic 3d models, An advanced, interface was developed for visualization and interaction with. the virtual environment of the Pathfinder landing site for mission scientists at the Space Flight Operations Facility of the Jet Propulsion Laboratory. The VR aspect of the display allowed mission scientists to navigate on Mars in Bud while remaining here on Earth, thus improving their spatial awareness of the rock field that surrounds the lenders Measurements of positions, distances and angles could be easily extracted from the topographic models, providing valuable information for science analysis and mission. planning. Moreover, the VR map of Mars has also been used to assist with the archiving and planning of activities for the Sojourner rover.

  16. Spiders from Mars?

    Science.gov (United States)

    2003-01-01

    MGS MOC Release No. MOC2-426, 19 July 2003No, this is not a picture of a giant, martian spider web. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of polygonal features on the floor of a northern hemisphere impact crater near 65.6oN, 327.7oW. The picture was acquired during spring, after the seasonal carbon dioxide frost cap had largely migrated through the region. At the time the picture was taken, remnants of seasonal frost remained on the crater rim and on the edges of the troughs that bound each of the polygons. Frost often provides a helpful hint as to where polygons and patterned ground occur. The polygons, if they were on Earth, would indicate the presence of freeze-thaw cycles in ground ice. Although uncertain, the same might be true of Mars. Sunlight illuminates the scene from the lower left.

  17. A simulation study of the thermosphere mass density response to substorms using GITM

    Science.gov (United States)

    Liu, Xianjing; Ridley, Aaron

    2015-09-01

    The temporal and spatial variations of the thermospheric mass density during a series of idealized substorms were investigated using the Global Ionosphere Thermosphere Model (GITM). The maximum mass density perturbation of an idealized substorm with a peak variation of hemispheric power (HP) of 50 GW and interplanetary magnetic field (IMF) Bz of -2 nT was ~14% about 50 min after the substorm onset in the nightside sector of the auroral zone. The mass density response to different types of energy input has a strong local time dependence, with the mass density perturbation due to only an IMF Bz variation peaking in the dusk sector and the density perturbation due to only HP variation peaks in the nightside sector. Simulations with IMF Bz changes only and HP changes only showed that the system behaves slightly nonlinearly when both IMF and HP variations are included (a maximum of 6% of the nonlinearity) and that the nonlinearity grows with energy input. The neutral gas heating rate due to Joule heating was of same magnitude as the heating rate due to precipitation, but the majority of the temperature enhancement due to the heating due to precipitation occurs at lower altitude as compared to the auroral heating. About 110 min after onset, a negative mass density perturbation (~-5%) occurred in the night sector, which was consistent with the mass density measurement of the CHAMP satellite.

  18. High-latitude energy input and its impact on the thermosphere

    Science.gov (United States)

    Lu, G.; Richmond, A. D.; Lühr, H.; Paxton, L.

    2016-07-01

    This paper presents a quantitative assessment of high-latitude energy input and its partitioning in the polar cap by synthesizing various space and ground-based observations during the 17 January 2005 geomagnetic storm. It was found that Joule heating is the primary form of magnetospheric energy input, especially during active times when the hemispheric-integrated Joule heating can be an order of magnitude larger than the hemispheric-integrated auroral power. Most of magnetospheric energy is dissipated in the auroral zone rather than in the polar cap. On average, only about 22-25% of the total hemispheric energy input is dissipated into the polar cap region bordered by the convection reversal boundary (CRB) and the poleward auroral flux boundary (FXB). The impact of high-latitude energy input was also investigated to unveil the causal relationship between Joule heating and the formation of polar cap mass density anomalies. Our numerical simulation demonstrated that thermosphere dynamics readily redistributes composition, temperature, and mass through upwelling and atmospheric gravity waves. The polar cap mass density anomalies observed by the CHAMP satellite during the storm were largely a result of large-scale atmospheric gravity waves. Therefore, an increase in local thermospheric mass density does not necessarily mean there is direct energy input.

  19. High-latitude lower thermospheric neutral winds at EISCAT and Sondrestrom during LTCS 1

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.M. (Univ. of Michigan, Ann Arbor (USA)); Virdi, T.S. (Univ. Coll. of Wales, Aberystwyth (England))

    1991-02-01

    The incoherent scatter radar located at Soendre Stroemfjord, Greenland (67{degree}N, 51{degree}W, 74.5{degree}{Lambda}) and the EISCAT incoherent scatter facility located in northern Scandinavia (69.5{degree}N, 19{degree}E, 66.3{degree}{Lambda}) both obtained E and F region measurements during the first campaign of the Lower Thermosphere Coupling Study (LTCS 1, September 21-25, 1987). Neutral winds deduced from these measurements have been analyzed for their mean flow and tidal components. A number of the altitude profiles for the mean winds and the diurnal and semidiurnal wave components at the two radar locations show similar variations with height, indicating that latitudinal rather than longitudinal effects are dominant in determining the observed wind field. Diurnal tidal amplitudes and phases are reasonably well represented by theoretical model results (Forbes, 1982). The semidiurnal amplitudes and phases, although somewhat consistent between the two radars, are not well represented in equinox tidal model results (Forbes and Vial, this issue). Results from both radars indicate a vertical wavelength for the zonal semidiurnal oscillation of approximately 60 km. During a period of impulsive magnetospheric forcing (September 22-23), winds deduced from measurements at both radars show enhanced eastward flows near midnight accompanied by equatorward winds at Sondrestrom. Comparison with the results of a National Center for Atmospheric Research thermosphere-ionosphere general circulation model (TIGCM) simulation of the LTCS 1 interval shows generally better agreement with the observations at EISCAT than at Sondrestrom.

  20. Scientific challenges in thermosphere-ionosphere forecasting - conclusions from the October 2014 NASA JPL community workshop

    Science.gov (United States)

    Mannucci, Anthony J.; Hagan, Maura E.; Vourlidas, Angelos; Huang, Cheryl Y.; Verkhoglyadova, Olga P.; Deng, Yue

    2016-10-01

    Interest in forecasting space weather in the thermosphere and ionosphere (T-I) led to a community workshop held at NASA's Jet Propulsion Laboratory in October, 2014. The workshop focus was "Scientific Challenges in Thermosphere-Ionosphere Forecasting" to emphasize that forecasting presumes a sufficiently advanced state of scientific knowledge, yet one that is still evolving. The purpose of the workshop, and this topical issue that arose from the workshop, was to discuss research frontiers that will lead to improved space weather forecasts. Three areas are discussed in some detail in this paper: (1) the role of lower atmosphere forcing in the response of the T-I to geomagnetic disturbances; (2) the significant deposition of energy at polar latitudes during geomagnetic disturbances; and (3) recent developments in understanding the propagation of coronal mass ejections through the heliosphere and prospects for forecasting the north-south component of the interplanetary magnetic field (IMF) using observations at the Lagrangian L5 point. We describe other research presented at the workshop that appears in the topical issue. The possibility of establishing a "positive feedback loop" where improved scientific knowledge leads to improved forecasts is described (Siscoe 2006, Space Weather, 4, S01003; Mannucci 2012, Space Weather, 10, S07003).

  1. Solar activity variations of nocturnal thermospheric meridional winds over Indian longitude sector

    Science.gov (United States)

    Madhav Haridas, M. K.; Manju, G.; Arunamani, T.

    2016-09-01

    The night time F-layer base height information from ionosondes located at two equatorial stations Trivandrum (TRV 8.5°N, 77°E) and Sriharikota (SHAR 13.7°N, 80.2°E) spanning over two decades are used to derive the climatology of equatorial nocturnal Thermospheric Meridional Winds (TMWs) prevailing during High Solar Activity (HSA) and Low Solar Activity (LSA) epochs. The important inferences from the analysis are 1) Increase in mean equatorward winds observed during LSA compared to HSA during pre midnight hours; 25 m/s for VE (Vernal Equinox) and 20 m/s for SS (Summer Solstice), AE (autumnal Equinox) and WS (Winter Solstice). 2) Mean wind response to Solar Flux Unit (SFU) is established quantitatively for all seasons for pre-midnight hours; rate of increase is 0.25 m/s/SFU for VE, 0.2 m/s/SFU for SS and WS and 0.08 m/s/SFU for AE. 3) Theoretical estimates of winds for the two epochs are performed and indicate the role of ion drag forcing as a major factor influencing TMWs. 4) Observed magnitude of winds and rate of flux dependencies are compared to thermospheric wind models. 5) Equinoctial asymmetry in TMWs is observed for HSA at certain times, with more equatorward winds during AE. These observations lend a potential to parameterize the wind components and effectively model the winds, catering to solar activity variations.

  2. Solar wind driving of ionosphere-thermosphere responses during three storms on St. Patrick's Day.

    Science.gov (United States)

    Verkhoglyadova, O. P.; Tsurutani, B.; Mannucci, A. J.; Komjathy, A.; Mlynczak, M. G.; Hunt, L. A.; Paxton, L. J.

    2015-12-01

    We overview solar wind features of three intense CME-driven storms occurring around the same time in March of 2012, 2013 and 2015 (74 - 80 DOY). Differences in solar wind drivers lead to different ionosphere-thermosphere (IT) responses in time, magnitude, and to different pre-conditioning. The purpose of our study is to establish a correspondence between interplanetary transient structures (parts of a CME or a high-speed-stream) and dynamics of IT parameters over the course of a geomagnetic storm. Detailed analysis will be presented for the St. Patrick's Day storm of 2015. We introduce global metrics of daytime and dusktime average ionospheric response of VTEC estimates from over ~2000 GPS ground stations distributed globally. Nitric oxide and carbon dioxide cooling radiation fluxes measured by TIMED/SABER instrument are calculated in several latitudinal bins throughout the storm phases. In addition, GUVI observations of the dynamical response of the thermosphere (NO and O/N2) are compared. SSUSI observations of the equatorial ionosphere, particularly the magnitude and separation of the equatorial arcs are considered. In our analysis, metrics are inter-compared to get better understanding of the self-consistent IT response to solar wind driving.

  3. Optical interferometric measurements of nighttime equatorial thermospheric winds at Arequipa, Peru

    Science.gov (United States)

    Meriwether, J. W., Jr.; Moody, J. W.; Biondi, M. A.; Roble, R. G.

    1986-01-01

    Nighttime measurements of equatorial thermospheric wind dynamics were obtained at Arequipa, Peru, with an automated field-widened Fabry-Perot interferometer between April 1983 and August 1983 and reduced data from 62 nights. Significant seasonal variations in both zonal and meridional components of the thermospheric neutral wind vector were observed. Near the equinox, between 2000 and 2300 LT, the zonal wind component is eastward with an amplitude between 100 and 150 m/s that gradually ebbs to zero by dawn. The meridional component is generally small throughout the night. In the winter months (May to August) and at the winter solstice, the zonal wind persists eastward throughout the night with speeds between 50 and 150 m/s. The meridional component is directed poleward (southward) toward the winter hemisphere with a speed of 50-75 m/s that decays to zero by midnight. Interferometric measurements of the 630.0-nm intensity at equinox showed a major reduction of the emission listing 1 or 2 hours in all directions but south shortly after evening twilight; this decrease was not observed during winter.

  4. Observations of meso-scale neutral wind interaction with auroral precipitation in the thermosphere at EISCAT

    Science.gov (United States)

    Kosch, Michael; Nozawa, Satonori; Yiu, Ho-Ching Iris; Anderson, Callum; Ogawa, Yasunobu; Howells, Vikki; Baddeley, Lisa; Aruliah, Anasuya; McWhirter, Ian; McCrea, I. W.; Fujii, Ryoichi

    We report on observations of E-region neutral wind fields and their interaction with auroral precipitation at meso-scale spatial resolution. The EISCAT Svalbard radar was used to observe the ionospheric line-of-sight ion flows and temperatures in the E-and F-regions whilst scan-ning its beam. An all-sky optical Scanning Doppler Imager was used at 557.7 nm to observe thermospheric neutral line-of-sight winds and temperatures. High-latitude data from February 2010 are presented. In the case of an auroral arc, strong acceleration of the E-region neutral wind occurs within 10s of km to the arc on a time scale of 10s of minutes. We demonstrate through modelling that this effect cannot be explained by height changes in the 557.7 nm emis-sion layer. The most likely explanation seems to be greatly enhanced ion drag associated with the increased plasma density caused by the particle precipitation, and the localised ionospheric electric field associated with the Pedersen closure current of auroral arcs. Since Joule heat-ing occurs predominantly in the E-region, meso-scale variability in the thermosphere probably accounts for a significant under-estimation in the total energy dissipation.

  5. Mars Aqueous Processing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Mars Aqueous Processing System (MAPS) is a novel technology for recovering oxygen, iron, and other constituents from lunar and Mars soils. The closed-loop...

  6. Hot Oxygen and Carbon Escape from the Early Atmosphere of Mars

    Science.gov (United States)

    Amerstorfer, U.; Gröller, H.; Lichtenegger, H.; Lammer, H.; Tian, F.

    2015-12-01

    Nowadays, the atmosphere of Mars is commonly assumed to be much different than in the early times of its evolution. Especially, the escape of water and carbon dioxide is thought to have formed its shape during millions of years. Also the Sun emitted a higher EUV flux in former times, influencing the particle environment around Mars.We study the escape of oxygen and carbon from the early Martian atmosphere for different EUV fluxes with a Monte-Carlo model. We consider different possible sources of hot oxygen and carbon atoms in the thermosphere, e.g. dissociative recombination of O2+ , CO+ and CO2+ , photodissociation of O2 and CO, and other reactions like charge transfer. From the calculated production rate profiles we can get insights into the importance of the different source reactions. The resulting energy distribution functions at the exobase level are used to study the exospheric densities and the escape of hot oxygen and carbon. We discuss the escape rates of those atoms and the importance of different source processes compared to the present situation at Mars.This work receives funding from the Austrian Science Fund (FWF): P 24247.

  7. The Mars Pathfinder Mission

    Science.gov (United States)

    Golombek, M. P.

    1996-09-01

    The Mars Pathfinder mission is a Discovery class mission that will place a small lander and rover on the surface of Mars on July 4, 1997. The Pathfinder flight system is a single small lander, packaged within an aeroshell and back cover with a back-pack-style cruise stage. The vehicle will be launched, fly independently to Mars, and enter the atmosphere directly on approach behind the aeroshell. The vehicle is slowed by a parachute and 3 small solid rockets before landing on inflated airbags. Petals of a small tetrahedron shaped lander open up, to right the vehicle. The lander is solar powered with batteries and will operate on the surface for up to a year, downlinking data on a high-gain antenna. Pathfinder will be the first mission to use a rover, with 3 imagers and an alpha proton X-ray spectrometer, to characterize the rocks and soils in a landing area over hundreds of square meters on Mars, which will provide a calibration point or "ground truth" for orbital remote sensing observations. The rover (includes a series of technology experiments), the instruments (including a stereo multispectral surface imager on a pop up mast and an atmospheric structure instrument-surface meteorology package) and the telemetry system will allow investigations of: the surface morphology and geology at meter scale, the petrology and geochemistry of rocks and soils, the magnetic properties of dust, soil mechanics and properties, a variety of atmospheric investigations and the rotational and orbital dynamics of Mars. Landing downstream from the mouth of a giant catastrophic outflow channel, Ares Vallis, offers the potential of identifying and analyzing a wide variety of crustal materials, from the ancient heavily cratered terrain, intermediate-aged ridged plains and reworked channel deposits, thus allowing first-order scientific investigations of the early differentiation and evolution of the crust, the development of weathering products and early environments and conditions on Mars.

  8. Flying To Mars

    Institute of Scientific and Technical Information of China (English)

    周铭杨

    2015-01-01

    <正>Do you know"Mars migration programme"by SpaceX?It’s an immigrant plan to a planet—Mars,Sounds incredible,isn’t it?After two-round tests,Li Dapeng,graduating from Handan NO.1 high school in 2001,was selected.There entered four Chinese in final test.To be more precise,Li is the only one who comes from the mainland of China.Last weekend,Li came to our school for a speech.Driven by

  9. EquiMar

    DEFF Research Database (Denmark)

    Johnstone, C. M.; McCombes, T.; Bahaj, A. S.

    2011-01-01

    / financiers etc when attempting to quantify the performance of a device since it makes it very difficult to reference and benchmark the performance of a marine energy converter. The EC Framework Programme VII EquiMar project has set out to develop a suite of Best Practices to be adopted when undertaking...... the performance evaluation of such systems in order to address this deficiency. This paper reports the development of a set of ‘Best Practices’ within the ECFPVII EquiMar project to be adopted for the performance quantification of wave and tidal energy converters as they evolve from an engineering concept...

  10. Mars Obliquity Cycle Illustration

    Science.gov (United States)

    2008-01-01

    The tilt of Mars' spin axis (obliquity) varies cyclically over hundreds of thousands of years, and affects the sunlight falling on the poles. Because the landing site of NASA's Phoenix Mars Lander is so near the north pole, higher sun and warmer temperatures during high obliquity lead to warmer, more humid surface environments, and perhaps thicker, more liquid-like films of water in soil. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  11. Lakes on Mars

    CERN Document Server

    Cabrol, Nathalie A

    2014-01-01

    On Earth, lakes provide favorable environments for the development of life and its preservation as fossils. They are extremely sensitive to climate fluctuations and to conditions within their watersheds. As such, lakes are unique markers of the impact of environmental changes. Past and current missions have now demonstrated that water once flowed at the surface of Mars early in its history. Evidence of ancient ponding has been uncovered at scales ranging from a few kilometers to possibly that of the Arctic ocean. Whether life existed on Mars is still unknown; upcoming missions may find critic

  12. Thermospheric mass density variations during geomagnetic storms and a prediction model based on the merging electric field

    NARCIS (Netherlands)

    Liu, R.; Lühr, H.; Doornbos, E.; Ma, S.Y.

    2010-01-01

    With the help of four years (2002–2005) of CHAMP accelerometer data we have investigated the dependence of low and mid latitude thermospheric density on the merging electric field, Em, during major magnetic storms. Altogether 30 intensive storm events (Dstmin <−100 nT) are chosen for a statistical s

  13. Ionospheric data assimilation with thermosphere-ionosphere-electrodynamics general circulation model and GPS-TEC during geomagnetic storm conditions

    Science.gov (United States)

    Chen, C. H.; Lin, C. H.; Matsuo, T.; Chen, W. H.; Lee, I. T.; Liu, J. Y.; Lin, J. T.; Hsu, C. T.

    2016-06-01

    The main purpose of this paper is to investigate the effects of rapid assimilation-forecast cycling on the performance of ionospheric data assimilation during geomagnetic storm conditions. An ensemble Kalman filter software developed by the National Center for Atmospheric Research (NCAR), called Data Assimilation Research Testbed, is applied to assimilate ground-based GPS total electron content (TEC) observations into a theoretical numerical model of the thermosphere and ionosphere (NCAR thermosphere-ionosphere-electrodynamics general circulation model) during the 26 September 2011 geomagnetic storm period. Effects of various assimilation-forecast cycle lengths: 60, 30, and 10 min on the ionospheric forecast are examined by using the global root-mean-squared observation-minus-forecast (OmF) TEC residuals. Substantial reduction in the global OmF for the 10 min assimilation-forecast cycling suggests that a rapid cycling ionospheric data assimilation system can greatly improve the quality of the model forecast during geomagnetic storm conditions. Furthermore, updating the thermospheric state variables in the coupled thermosphere-ionosphere forecast model in the assimilation step is an important factor in improving the trajectory of model forecasting. The shorter assimilation-forecast cycling (10 min in this paper) helps to restrain unrealistic model error growth during the forecast step due to the imbalance among model state variables resulting from an inadequate state update, which in turn leads to a greater forecast accuracy.

  14. Nitrogen Chemistry in Titan's Upper Atmosphere

    Science.gov (United States)

    Kammer, J. A.; Shemansky, D. E.; Zhang, X.; Yung, Y. L.

    2012-04-01

    Titan’s atmosphere has evolved over time into its current state through complex photochemical processes (Yung et al. 1984), involving nitrogen (N2), the dominant molecular species in the atmosphere, as well as methane (CH4). It has been proposed that this composition may be analogous to the early Earth’s, as it certainly provides an abundance of hydrocarbons the like from which early life may have arisen (Coustenis & Taylor 1999; Lunine 2005). Recent results from the Cassini spacecraft have greatly improved our knowledge of the current state of Titan’s atmosphere, and measurements made by the Ultraviolet Imaging Spectrograph (UVIS) in particular are able to probe the region of interest from 400 km to 1500 km in altitude where much of the photochemistry on Titan occurs (Shemansky et al. 2005, Koskinen et al. 2011). This photochemistry in part converts nitrogen from stable N2 molecules and incorporates it into detectable hydrocarbon products such as HCN, HC3N, and other heavier compounds. Therefore the nitrogen story is of particular interest, and we examine UVIS occultation observations in both the EUV and FUV regions of the spectrum in order to directly retrieve the vertical profiles of N2 in addition to its related hydrocarbon derivatives. Constraints from UVIS on temperature profiles of the upper atmosphere are also examined and compared to current results from the Ion and Neutral Mass Spectrometer (INMS), which probes a region above 1000 km altitude in Titan’s atmosphere (Westlake et al. 2011). References: Coustenis, A., and F. Taylor: “Titan: The Earth-Like Moon”. Singapore: World Scientific, 1999. Koskinen, T. T., et al.: “The mesosphere and thermosphere of Titan revealed by Cassini/UVIS stellar occultations”. Icarus, Vol. 216, pp. 507-534, 2011. Lunine, J. I.: “Astrobiology: A Multidisciplinary Approach”. San Francisco, CA: Pearson Addison Wesley, 2005. Shemansky, D. E., et al.: “The Cassini UVIS stellar probe of the Titan atmosphere

  15. Vulkanisme en water op Mars?

    NARCIS (Netherlands)

    Van Loef, J.; Schmets, A.J.M.

    2005-01-01

    In januari 2004 werd Mars bezocht door de tweeling robotverkenners Spirit en Opportunity. Zij werden erop uitgestuurd om eindelijk het definitieve antwoord te geven op de vraag of er leven op Mars is geweest. Alles wijst er inmiddels op dat er op Mars ooit vloeibaar water stroomde. Of daarmee een

  16. Vulkanisme en water op Mars?

    NARCIS (Netherlands)

    Van Loef, J.; Schmets, A.J.M.

    2005-01-01

    In januari 2004 werd Mars bezocht door de tweeling robotverkenners Spirit en Opportunity. Zij werden erop uitgestuurd om eindelijk het definitieve antwoord te geven op de vraag of er leven op Mars is geweest. Alles wijst er inmiddels op dat er op Mars ooit vloeibaar water stroomde. Of daarmee een be

  17. Vulkanisme en water op Mars?

    NARCIS (Netherlands)

    Van Loef, J.; Schmets, A.J.M.

    2005-01-01

    In januari 2004 werd Mars bezocht door de tweeling robotverkenners Spirit en Opportunity. Zij werden erop uitgestuurd om eindelijk het definitieve antwoord te geven op de vraag of er leven op Mars is geweest. Alles wijst er inmiddels op dat er op Mars ooit vloeibaar water stroomde. Of daarmee een be

  18. Short Time-Scale Enhancements to the Global Thermosphere Temperature and Nitric Oxide Content Resulting From Ionospheric Joule Heating

    Science.gov (United States)

    Weimer, D. R.; Mlynczak, M. G.; Hunt, L. A.; Sutton, E. K.

    2014-12-01

    The total Joule heating in the polar ionosphere can be derived from an empirical model of the electric fields and currents, using input measurements of the solar wind velocity and interplanetary magnetic field (IMF). In the thermosphere, measurements of the neutral density from accelerometers on the CHAMP and GRACE satellites are used to derive exospheric temperatures, showing that enhanced ionospheric energy dissipation produces elevated temperatures with little delay.Using the total ionospheric heating, changes in the global mean exosphere temperature as a function of time can be calculated with a simple differential equation. The results compare very well with the CHAMP and GRACE measurement. A critical part of the calculation is the rate at which the thermosphere cools after the ionospheric heating is reduced. It had been noted previously that events with significant levels of heating subsequently cool at a faster rate, and this cooling was attributed to enhanced nitric oxide emissions. This correlation with nitric oxide has been confirmed with very high correlations with measurements of nitric oxide emissions in the thermosphere, from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite. These measurements were used in a recent improvement in the equations that calculate the thermosphere temperature. The global nitric oxide cooling rates are included in this calculation, and the predicted levels of nitric oxide, derived from the ionosphere heating model, match the SABER measurements very well, having correlation coefficients on the order of 0.9.These calculations are used to govern the sorting of measurements CHAMP and GRACE measurements, on the basis of the global temperature enhancements due to Joule heating, as well as various solar indices, and season. Global maps of the exospheric temperature are produced from these sorted data.

  19. Estimation of energy budget of ionosphere-thermosphere system during two CIR-HSS events: observations and modeling

    Directory of Open Access Journals (Sweden)

    Verkhoglyadova Olga

    2016-01-01

    Full Text Available We analyze the energy budget of the ionosphere-thermosphere (IT system during two High-Speed Streams (HSSs on 22–31 January, 2007 (in the descending phase of solar cycle 23 and 25 April–2 May, 2011 (in the ascending phase of solar cycle 24 to understand typical features, similarities, and differences in magnetosphere-ionosphere-thermosphere (IT coupling during HSS geomagnetic activity. We focus on the solar wind energy input into the magnetosphere (by using coupling functions and energy partitioning within the IT system during these intervals. The Joule heating is estimated empirically. Hemispheric power is estimated based on satellite measurements. We utilize observations from TIMED/SABER (Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry to estimate nitric oxide (NO and carbon dioxide (CO2 cooling emission fluxes. We perform a detailed modeling study of these two similar HSS events with the Global Ionosphere-Thermosphere Model (GITM and different external driving inputs to understand the IT response and to address how well the model reproduces the energy transport. GITM is run in a mode with forecastable inputs. It is shown that the model captures the main features of the energy coupling, but underestimates NO cooling and auroral heating in high latitudes. Lower thermospheric forcing at 100 km altitude is important for correct energy balance of the IT system. We discuss challenges for a physics-based general forecasting approach in modeling the energy budget of moderate IT storms caused by HSSs.

  20. Gravity Waves in the Atmospheres of Mars and Venus

    Science.gov (United States)

    Tellmann, Silvia; Paetzold, Martin; Häusler, Bernd; Bird, Michael K.; Tyler, G. Leonard; Hinson, David P.; Imamura, Takeshi

    2016-10-01

    Gravity waves are ubiquitous in all stably stratified planetary atmospheres and play a major role in the redistribution of energy and momentum. Gravity waves can be excited by many different mechanisms, e.g. by airflow over orographic obstacles or by convection in an adjacent layer.Gravity waves on Mars were observed in the lower atmosphere [1,2] but are also expected to play a major role in the cooling of the thermosphere [3] and the polar warming [4]. They might be excited by convection in the daytime boundary layer or by strong winter jets in combination with the pronounced topographic diversity on Mars.On Venus, gravity waves play an important role in the mesosphere above the cloud layer [5] and probably below. Convection in the cloud layer is one of the most important source mechanisms but certain correlations with topography were observed by different experiments [6,7,8].Temperature height profiles from the radio science experiments on Mars Express (MaRS) [9] and Venus Express (VeRa) [10] have the exceptionally high vertical resolution necessary to study small-scale vertical gravity waves, their global distribution, and possible source mechanisms.Atmospheric instabilities, which are clearly identified in the data, can be investigated to gain further insight into possible atmospheric processes contributing to the excitation of gravity waves.[1] Creasey, J. E., et al.,(2006), Geophys. Res. Lett., 33, L01803, doi:10.1029/2005GL024037.[2]Tellmann, S., et al.(2013), J. Geophys. Res. Planets, 118, 306-320, doi:10.1002/jgre.20058.[3]Medvedev, A. S., et al.(2015), J. Geophys. Res. Planets, 120, 913-927. doi:10.1002/2015JE004802.[4] Barnes, J. R. (1990), J. Geophys. Res., 95, B2, 1401-1421.[5] Tellmann, S., et al. (2012), Icarus, 221, 471 - 480.[6] Blamont, J.E. et al., (1986) 231, 1422-1425.[7] Bertaux J.-L., et al. (2016), J. Geophys. Res., Planets, in press.[8] Piccialli, A., et al. (2014), Icarus, 227, 94 - 111.[9] Pätzold, M., et al. (2016), Planet. Space Sci

  1. Ancient aliens on mars

    CERN Document Server

    Bara, Mike

    2013-01-01

    Best-selling author and Secret Space Program researcher Bara brings us this lavishly illustrated volume on alien structures on Mars. Was there once a vast, technologically advanced civilization on Mars, and did it leave evidence of its existence behind for humans to find eons later? Did these advanced extraterrestrial visitors vanish in a solar system wide cataclysm of their own making, only to make their way to Earth and start anew? Was Mars once as lush and green as the Earth, and teeming with life? Did Mars once orbit a missing member of the solar system, a "Super Earth” that vanished in a disaster that devastated life on Earth and Venus and left us only the asteroid belt as evidence of its once grand existence? Did the survivors of this catastrophe leave monuments and temples behind, arranged in a mathematical precision designed to teach us the Secret of a new physics that could lift us back to the stars? Does the planet have an automated defense shield that swallows up robotic probes if they wander int...

  2. Mission from Mars

    DEFF Research Database (Denmark)

    Dindler, Christian; Eriksson, Eva; Iversen, Ole Sejer

    2005-01-01

    In this paper a particular design method is propagated as a supplement to existing descriptive approaches to current practice studies especially suitable for gathering requirements for the design of children's technology. The Mission from Mars method was applied during the design of an electronic...

  3. Carbon sequestration on Mars

    OpenAIRE

    Edwards, Christopher S.; Ehlmann, Bethany L.

    2015-01-01

    On Earth, carbon sequestration in geologic units plays an important role in the carbon cycle, scrubbing CO_2 from the atmosphere for long-term storage. While carbonate is identified in low abundances within the dust and soils of Mars, at

  4. Mission from Mars:

    DEFF Research Database (Denmark)

    Dindler, Christian; Eriksson, Eva; Iversen, Ole Sejer

    2005-01-01

    In this paper a particular design method is propagated as a supplement to existing descriptive approaches to current practice studies especially suitable for gathering requirements for the design of children's technology. The Mission from Mars method was applied during the design of an electronic...

  5. The Phoenix Mars Mission

    Science.gov (United States)

    Tamppari, Leslie K.; Smith, Peter H.

    2008-01-01

    This slide presentation details the Phoenix Mission which was designed to enhance our understanding of water and the potential for habitability on the north polar regions of Mars. The slides show the instruments and the robotics designed to scrape Martian surface material, and analyze it in hopes of identifying water in the form of ice, and other chemicals.

  6. [MaRS Project

    Science.gov (United States)

    Aruljothi, Arunvenkatesh

    2016-01-01

    The Space Exploration Division of the Safety and Mission Assurances Directorate is responsible for reducing the risk to Human Space Flight Programs by providing system safety, reliability, and risk analysis. The Risk & Reliability Analysis branch plays a part in this by utilizing Probabilistic Risk Assessment (PRA) and Reliability and Maintainability (R&M) tools to identify possible types of failure and effective solutions. A continuous effort of this branch is MaRS, or Mass and Reliability System, a tool that was the focus of this internship. Future long duration space missions will have to find a balance between the mass and reliability of their spare parts. They will be unable take spares of everything and will have to determine what is most likely to require maintenance and spares. Currently there is no database that combines mass and reliability data of low level space-grade components. MaRS aims to be the first database to do this. The data in MaRS will be based on the hardware flown on the International Space Stations (ISS). The components on the ISS have a long history and are well documented, making them the perfect source. Currently, MaRS is a functioning excel workbook database; the backend is complete and only requires optimization. MaRS has been populated with all the assemblies and their components that are used on the ISS; the failures of these components are updated regularly. This project was a continuation on the efforts of previous intern groups. Once complete, R&M engineers working on future space flight missions will be able to quickly access failure and mass data on assemblies and components, allowing them to make important decisions and tradeoffs.

  7. Mars Surface Environmental Issues

    Science.gov (United States)

    Charles, John

    2002-01-01

    Planetary exploration by astronauts will require extended periods of habitation on a planet's surface, under the influence of environmental factors that are different from those of Earth and the spacecraft that delivered the crew to the planet. Human exploration of Mars, a possible near-term planetary objective, can be considered a challenging scenario. Mission scenarios currently under consideration call for surface habitation periods of from 1 to 18 months on even the earliest expeditions. Methods: Environmental issues associated with Mars exploration have been investigated by NASA and the National Space Biomedical Research Institute (NSBRI) as part of the Bioastronautics Critical Path Roadmap Project (see http ://criticalpath.jsc.nasa.gov). Results: Arrival on Mars will immediately expose the crew to gravity only 38% of that at Earth's surface in possibly the first prolonged exposure to gravity other than the 1G of Earth's surface and the zero G of weightless space flight, with yet unknown effects on crew physiology. The radiation at Mars' surface is not well documented, although the planet's bulk and even its thin atmosphere may moderate the influx of galactic cosmic radiation and energetic protons from solar flares. Secondary radiation from activated components of the soil must also be considered. Ultrafine and larger respirable and nonrespirable particles in Martian dust introduced into the habitat after surface excursions may induce pulmonary inflammation exacerbated by the additive reactive and oxidizing nature of the dust. Stringent decontamination cannot eliminate mechanical and corrosive effects of the dust on pressure suits and exposed machinery. The biohazard potential of putative indigenous Martian microorganisms may be assessed by comparison with analog environments on Earth. Even in their absence, human microorganisms, if not properly controlled, can be a threat to the crew's health. Conclusions: Mars' surface offers a substantial challenge to the

  8. Evidence for two-dimensional turbulence proceses in the lower thermosphere

    Science.gov (United States)

    Larsen, M. F.

    2010-12-01

    A striking feature of chemical release trails in the lower thermosphere is the transition from turbulent flow to apparently laminar flow at the nominal turbopause height. The transition is very sharp, occurring over a vertical distance of a few hundred meters or less and is easily recognizable in the images. Detailed quantitative information about turbulence properties in the critical transition region is difficult to obtain. The chemical trails are one of the few sources of such information, although extracting information about turbulent energy dissipation rates and turbulent diffusion coefficients requires images with good time and angular resolution and is a time intensive analysis process. The number of such analyses is therefore limited, but the results consistently show direct evidence of anomalous diffusion over an altitude range that extends 10-15 km above the nominal turbopause, i.e., in an altitude range where the flow qualitatively appears to be laminar. Anomalous diffusion, in this case, refers to tracer expansion that is more rapid than expected from molecular diffusion alone. The region where the anomalous trail expansion is found is also characterized by large wind speeds that tend to maximize within that altitude range. The maximum winds generally exceed 80 m/s and are often in the 100 to 150 m/s range, as shown by a large database of more than 500 chemical release wind measurements obtained over an extended period at a variety of locations and local times. In addition, rapid transport of Space Shuttle exhaust products from low to high latitudes is also known to occur in the same altitude range, suggesting that the transport is effective over large scales. The observational evidence thus indicates that the lower thermosphere, in the altitude range between 100 and 115 km, is a region of enhanced anomalous transport that operates over a broad range of spatial scales, from a kilometer or less to the planetary scale. Evidence for two

  9. 3-Dimensional numerical simulations of the dynamics of the Venusian mesosphere and thermosphere

    Science.gov (United States)

    Tingle, S.; Mueller-Wodarg, I. C.

    2009-12-01

    We present the first results from a new 3-dimensional numerical simulation of the steady state dynamics of the Venusian mesosphere and thermosphere (60-300 km). We have adapted the dynamical core of the Titan thermosphere global circulation model (GCM) [1] to a steady state background atmosphere. Our background atmosphere is derived from a hydrostatic combination of the VTS3 [2] and Venus International Reference Atmosphere (VIRA) [3] empirical models, which are otherwise discontinuous at their 100 km interface. We use 4th order polynomials to link the VTS3 and VIRA thermal profiles and employ hydrostatic balance to derive a consistent density profile. We also present comparisons of our background atmosphere to data from the ESA Venus Express Mission. The thermal structure of the Venusian mesosphere is relatively well documented; however, direct measurements of wind speeds are limited. Venus’ slow rotation results in a negligible Coriolis force. This suggests that the zonal circulation should arise from cyclostrophic balance; where the equatorward component of the centrifugal force balances poleward meridional pressure gradients [4]. The sparseness of direct and in-situ measurements has resulted in the application of cyclostrophic balance to measured thermal profiles to derive wind speeds [5] [6] [7] [8]. However, cyclostrophic balance is only strictly valid at mid latitudes (˜ ± 30-75°) and its applicability to the Venusian mesosphere has not been conclusively demonstrated. Our simulations, by solving the full Navier-Stokes momentum equation, will enable us assess the validity of cyclostrophic balance as a description of mesospheric dynamics. This work is part of an ongoing project to develop the first GCM to encompass the atmosphere from the cloud tops into the thermosphere. When complete, this model will enable self-consistent calculations of the dynamics, energy and composition of the atmosphere. It will thus provide a framework to address many of the

  10. Mars EXpress: status and recent findings

    Science.gov (United States)

    Titov, Dmitri; Bibring, Jean-Pierre; Cardesin, Alejandro; Duxbury, Tom; Forget, Francois; Giuranna, Marco; Holmstroem, Mats; Jaumann, Ralf; Martin, Patrick; Montmessin, Franck; Orosei, Roberto; Paetzold, Martin; Plaut, Jeff; MEX SGS Team

    2016-04-01

    Mars Express has entered its second decade in orbit in excellent health. The mission extension in 2015-2016 aims at augmenting of the surface coverage by imaging and spectral imaging instruments, continuing monitoring of the climate parameters and their variability, study of the upper atmosphere and its interaction with the solar wind in collaboration with NASA's MAVEN mission. Characterization of geological processes and landforms on Mars on a local-to-regional scale by HRSC camera constrained the martian geological activity in space and time and suggested its episodicity. Six years of spectro-imaging observations by OMEGA allowed correction of the surface albedo for presence of the atmospheric dust and revealed changes associated with the dust storm seasons. Imaging and spectral imaging of the surface shed light on past and present aqueous activity and contributed to the selection of the Mars-2018 landing sites. More than a decade long record of climatological parameters such as temperature, dust loading, water vapor, and ozone abundance was established by SPICAM and PFS spectrometers. Observed variations of HDO/H2O ratio above the subliming North polar cap suggested seasonal fractionation. The distribution of aurora was found to be related to the crustal magnetic field. ASPERA observations of ion escape covering a complete solar cycle revealed important dependences of the atmospheric erosion rate on parameters of the solar wind and EUV flux. Structure of the ionosphere sounded by MARSIS radar and MaRS radio science experiment was found to be significantly affected by the solar activity, crustal magnetic field as well as by influx of meteorite and cometary dust. The new atlas of Phobos based on the HRSC imaging was issued. The talk will give the mission status and review recent science highlights.

  11. Recommended Maximum Temperature For Mars Returned Samples

    Science.gov (United States)

    Beaty, D. W.; McSween, H. Y.; Czaja, A. D.; Goreva, Y. S.; Hausrath, E.; Herd, C. D. K.; Humayun, M.; McCubbin, F. M.; McLennan, S. M.; Hays, L. E.

    2016-01-01

    The Returned Sample Science Board (RSSB) was established in 2015 by NASA to provide expertise from the planetary sample community to the Mars 2020 Project. The RSSB's first task was to address the effect of heating during acquisition and storage of samples on scientific investigations that could be expected to be conducted if the samples are returned to Earth. Sample heating may cause changes that could ad-versely affect scientific investigations. Previous studies of temperature requirements for returned mar-tian samples fall within a wide range (-73 to 50 degrees Centigrade) and, for mission concepts that have a life detection component, the recommended threshold was less than or equal to -20 degrees Centigrade. The RSSB was asked by the Mars 2020 project to determine whether or not a temperature requirement was needed within the range of 30 to 70 degrees Centigrade. There are eight expected temperature regimes to which the samples could be exposed, from the moment that they are drilled until they are placed into a temperature-controlled environment on Earth. Two of those - heating during sample acquisition (drilling) and heating while cached on the Martian surface - potentially subject samples to the highest temperatures. The RSSB focused on the upper temperature limit that Mars samples should be allowed to reach. We considered 11 scientific investigations where thermal excursions may have an adverse effect on the science outcome. Those are: (T-1) organic geochemistry, (T-2) stable isotope geochemistry, (T-3) prevention of mineral hydration/dehydration and phase transformation, (T-4) retention of water, (T-5) characterization of amorphous materials, (T-6) putative Martian organisms, (T-7) oxidation/reduction reactions, (T-8) (sup 4) He thermochronometry, (T-9) radiometric dating using fission, cosmic-ray or solar-flare tracks, (T-10) analyses of trapped gasses, and (T-11) magnetic studies.

  12. Upper Limb Exoskeleton

    NARCIS (Netherlands)

    Rusak, Z.; Luijten, J.; Kooijman, A.

    2015-01-01

    The present invention relates a wearable exoskeleton for a user having a torso with an upper limb to support motion of the said upper limb. The wearable exoskeleton comprises a first fixed frame mountable to the torso, an upper arm brace and a first group of actuators for moving the upper arm brace

  13. Upper Limb Exoskeleton

    NARCIS (Netherlands)

    Rusak, Z.; Luijten, J.; Kooijman, A.

    2015-01-01

    The present invention relates a wearable exoskeleton for a user having a torso with an upper limb to support motion of the said upper limb. The wearable exoskeleton comprises a first fixed frame mountable to the torso, an upper arm brace and a first group of actuators for moving the upper arm brace

  14. Small Step or Giant Leap - Human Locomotion on Mars

    Science.gov (United States)

    Hawkey, A.

    Human locomotion on Mars will be considerably different from on Earth. Optimum walking speeds will be approximately 30% lower and transitioning from a walk to a run will occur at a speed 25% slower. Peak vertical forces will be reduced by as much as 50%, and although ground contact time will remain constant with locomotion in 1g, stride length and stride time will increase. During running on Mars airborne time will increase by approximately 80% in comparison to running on the Earth. On Mars, half as much energy will be required to travel the equivalent distance on Earth and it will be 65% more economical to run rather than to walk. Crews will, therefore, find themselves using a loping gait - a running-like action, with a slight upper body lean and an extended aerial phase, an unfamiliar gait in terrestrial locomotion.

  15. Navigation strategy with the spacecraft communications blackout for Mars entry

    Science.gov (United States)

    Wang, Xichen; Xia, Yuanqing

    2015-02-01

    Future Mars missions require precision entry navigation capability, especially in the presence of communications blackout. On the mission of Mars Science Laboratory (MSL), there was a 70-s communications blackout period during atmospheric entry phase. In allusion to the spacecraft communications blackout encountered, this paper predicts an upper-bound for any possible blackout period firstly, improves the default integrated navigation measurements based on IMU and surface radiometric beacons, and proposes innovative attitude observation model based on IMU and range observation model based on orbiters finally. To verify the accuracy and effectiveness of the proposed observation models in the presence of communications blackout, unscented Kalman filter is utilized to demonstrate the navigation performance. The results show that navigation errors based on improved observation models proposed in this paper degrade an order of magnitude compared with the default observation models even if the communications blackout takes place, which satisfies the requirements of future Mars landing missions.

  16. Icebergs on early Mars

    Science.gov (United States)

    Uceda, E.; Fairen, A.; Woodworth-Lynas, C.; Palmero Rodriguez, A.

    2015-12-01

    The smooth topography of the Martian northern lowlands has been classically equated to an ancient ocean basin. The High-Resolution Imaging Science Experiment (HiRISE) onboard the Mars Reconnaissance Orbiter (MRO) is providing unprecedented images of the Martian surface at scales of 25 to 32 cm per pixel. The analysis of this high-resolution imaging reveals the presence of three differentiated geomorphologies throughout the northern lowlands of Mars and the Hellas basin, which are informative of the presence of icebergs floating in ancient oceans and/or seas. These morphologies are: (i) scattered scour marks, including curvilinear furrows several km long and some meters deep; (ii) boulders ranging in size from 0.5 m to ~2 m in diameter, distributed forming clusters with sizes from several hundred meters to 1-2 km; and (iii) flat-topped and conical circular fractured mounds. The association of plough marks, clusters of boulders and mounds on the northern plains of Mars can be related to the dual processes of ice keel scouring and ice rafting of both glacial and non-glacial detritus by a floating ice canopy and icebergs. These processes are well documented on Earth and result in distinct morphologies on the ocean floor, which are analogous to features observed in the Martian basins. Importantly, the features are located in elevated areas of the northern plains and Hellas, near the dichotomy boundary and on local topographic highs. Such distribution is expected, as these relatively shoal areas are where the iceberg-related features should occur on Mars: these areas had shallow water depths, less than the iceberg's keel depth, and therefore keels reached through the full depth of the water column to impinge on the sediments below. The presence of icebergs floating in cold oceans early in Mars' history imply the occurrence of continental glaciers forming in the highlands and streaming northward towards the lowlands, and towards the Hellas and Argyre Basins. Glacier

  17. Thermosphere-ionosphere-mesosphere energetics and dynamics (TIMED). The TIMED mission and science program report of the science definition team. Volume 1: Executive summary

    Science.gov (United States)

    1991-01-01

    A Science Definition Team was established in December 1990 by the Space Physics Division, NASA, to develop a satellite program to conduct research on the energetics, dynamics, and chemistry of the mesosphere and lower thermosphere/ionosphere. This two-volume publication describes the TIMED (Thermosphere-Ionosphere-Mesosphere, Energetics and Dynamics) mission and associated science program. The report outlines the scientific objectives of the mission, the program requirements, and the approach towards meeting these requirements.

  18. Assessing the performance of thermospheric modelling with data assimilation throughout solar cycles 23 and 24

    CERN Document Server

    Murray, Sophie A; Jackson, David R; Bruinsma, Sean L

    2015-01-01

    Data assimilation procedures have been developed for thermospheric models using satellite density measurements as part of the EU Framework Package 7 ATMOP Project. Two models were studied; one a general circulation model, TIEGCM, and the other a semi-empirical drag temperature model, DTM. Results of runs using data assimilation with these models were compared with independent density observations from CHAMP and GRACE satellites throughout solar cycles 23 and 24. Time periods of 60 days were examined at solar minimum and maximum, including the 2003 Hallowe'en storms. The differences between the physical and the semi-empirical models have been characterised. Results indicate that both models tend to show similar behaviour; underestimating densities at solar maximum, and overestimating them at solar minimum. DTM performed better at solar minimum, with both models less accurate at solar maximum. A mean improvement of ~4% was found using data assimilation with TIEGCM. With further improvements, the use of general ...

  19. Diagnosis of chemistry-dynamics interactions in the mesosphere and lower thermosphere

    Science.gov (United States)

    Zhu, X.; Garcia, R. R.; Swartz, W.; Yee, J. H.; Yue, J.

    2016-12-01

    We apply the recently developed middle atmosphere climate feedback-response analysis method (MCFRAM) to diagnosing the temperature variations associated with chemistry-dynamics interactions in the mesosphere and lower thermosphere (MLT). By using measurements from the Sounding of the Atmosphere using Broadband Emission Radiometer (SABER) onboard the TIMED satellite and the Whole Atmosphere Community Climate Model (WACCM), we identify and isolate the distinctive characteristics of different components in the observed temperature variations. Both the temperature trends associated with the anthropogenic forcing and temperature changes associated with natural and internal feedback processes are quantified based on MCFRAM defined partial temperature changes corresponding to localized radiative heating, non-localized chemical heating, eddy transport, and transport by the mean meridional circulation of energy and chemical species.

  20. Soft Particle Spectrometer, Langmuir Probe, and Data Analysis for Aerospace Magnetospheric/Thermospheric Coupling Rocket Program

    Science.gov (United States)

    Sharber, J. R.; Frahm, R. A.; Scherrer, J. R.

    1997-01-01

    Under this grant two instruments, a soft particle spectrometer and a Langmuir probe, were refurbished and calibrated, and flown on three instrumented rocket payloads as part of the Magnetosphere/Thermosphere Coupling program. The flights took place at the Poker Flat Research Range on February 12, 1994 (T(sub o) = 1316:00 UT), February 2, 1995 (T(sub o) = 1527:20 UT), and November 27, 1995 (T(sub o) = 0807:24 UT). In this report the observations of the particle instrumentation flown on all three of the flights are described, and brief descriptions of relevant geophysical activity for each flight are provided. Calibrations of the particle instrumentation for all ARIA flights are also provided.

  1. Equatorial thermospheric wind changes during the solar cycle - Measurements at Arequipa, Peru, from 1983 to 1990

    Science.gov (United States)

    Biondi, M. A.; Meriwether, J. W., Jr.; Fejer, B. G.; Gonzalez, S. A.; Hallenbeck, D. C.

    1991-01-01

    Near-equatorial thermospheric wind velocities at Arequipa, Peru, are determined over about two-thirds of a solar cycle using Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630-nm emission line. Mean monthly nocturnal variations in the meridional and zonal wind components are calculated from the nightly data to remove short-term (day-to-day) variability as well as any additional changes introduced by the progression of the solar cycle. For most of the years, at the winter solstice, there is a weak (more than 100 m/s) transequatorial flow from the summer to the winter hemisphere in the early and the late night, with essentially zero velocities in between. At the equinoxes, an early-night poleward (southward) flow at solar minimum (1986) is replaced by an equatorward (northward) flow at solar maximum (1989-1990).

  2. The neutral atmosphere temperature experiment. [for thermospheric nitrogen measurement on AEROS satellite

    Science.gov (United States)

    Spencer, N. W.; Pelz, D. T.; Niemann, H. B.; Carignan, G. R.; Caldwell, J. R.

    1974-01-01

    The AEROS Neutral Atmosphere Temperature Experiment (NATE) is designed to measure the kinetic temperature of molecular nitrogen in the thermosphere. A quadrupole mass spectrometer tuned to N2 measures the N2 density variation in a small spherical antechamber having a knife-edged orifice which is exposed to the atmosphere at the outer surface of the spacecraft. The changing density of N2 due to the spinning motion of the spacecraft permits determination of the velocity distribution of the N2 from which the temperature is calculated. An alternate mode of operation of the instrument allows measurement of the other gases in the atmosphere as well as N2 permitting determination of the neutral particle composition of the atmosphere.

  3. Mesosphere and Lower Thermosphere Winds from space: A decade and a half of observations

    Science.gov (United States)

    Skinner, W. R.; Niciejewski, R.; Gell, D. A.; Cooper, M.; Marshall, A. R.; Solomon, S. C.; Wu, Q.; Killeen, T. L.; Ortland, D. A.

    2006-05-01

    Continuous space borne observations of the mesosphere and lower thermosphere wind field have now been made for more than 14 years. Wind measurements commenced in late 1991 with two wind sensing instrument on the UARS spacecraft (HRDI and WINDII) and continue to the present with the TIDI instrument on TIMED. The HRDI and WINDII instruments operated simultaneously during much of the operational life of UARS and have been extensively validated. Both TIDI and HRDI obtained measurements from 2002 to 2005 providing a very desirable three year overlap to cross calibrate the instruments. The length of this combined data set permits study of the inter-annual variability of this part of the atmosphere. This paper discusses some of longer term phenomena that have been studied.

  4. Solar flare impact on FUV based thermospheric O/N2 estimation

    Science.gov (United States)

    Zhang, Y.; Paxton, L. J.; Kil, H.

    2016-09-01

    During/after intense solar flares, FUV based thermospheric O/N2 ratio decreases and recovers instantly, indicating that the decrease is not physical. Simulations with an increased solar X-ray (0-10 nm) flux and a fixed O and N2 profiles show a significant 135.6 nm/LBHS decrease that is sufficient to explain the O/N2 decrease. The false O/N2 decrease is mostly due to increased differences in O2 absorption at 135.6 nm and LBHS caused by low-altitude emissions associated with enhanced X-rays. However, the heating from solar flares may cause a weak depletion in O/N2.

  5. Storm time variation of radiative cooling of thermosphere by nitric oxide emission

    Science.gov (United States)

    Krishna, M. V. Sunil; Bag, Tikemani; Bharti, Gaurav

    2016-07-01

    The fundamental vibration-rotation band emission (Δν=1, Δ j=0,± 1) by nitric oxide (NO) at 5.3 µm is one of the most important cooling mechanisms in thermosphere. The collisional vibrational excitation of NO(ν=0) by impact with atomic oxygen is the main source of vibrationally excited nitric oxide. The variation of NO density depends on latitude, longitude and season. The present study aims to understand how the radiative flux gets influenced by the severe geomagnetic storm conditions. The variation of Nitric Oxide (NO) radiative flux exiting thermosphere is studied during the superstorm event of 7-12 November, 2004. The observations of TIMED/SABER suggest a strong anti-correlation with the O/N_2 ratio observed by GUVI during the same period. On a global scale the NO radiative flux showed an enhancement during the main phase on 8 November, 2004, whereas maximum depletion in O/N_2 is observed on 10 November, 2004. Both O/N_2 and NO radiative flux were found to propagate equatorward due to the effect of meridional wind resulting from joule and particle heating in polar region. Larger penetrations is observed in western longitude sectors. These observed variations are effectively connected to the variations in neutral densities. In the equatorial sectors, O/N_2 shows enhancement but almost no variation in radiative flux is observed. The possible reasons for the observed variations in NO radiative emission and O/N_2 ratios are discussed in the light of equator ward increase in the densities and prompt penetration.

  6. Lower thermospheric wind variations in auroral patches during the substorm recovery phase

    Science.gov (United States)

    Oyama, Shin-ichiro; Shiokawa, Kazuo; Miyoshi, Yoshizumi; Hosokawa, Keisuke; Watkins, Brenton J.; Kurihara, Junichi; Tsuda, Takuo T.; Fallen, Christopher T.

    2016-04-01

    Measurements of the lower thermospheric wind with a Fabry-Perot interferometer (FPI) at Tromsø, Norway, found the largest wind variations in a night during the appearance of auroral patches at the substorm recovery phase. Taking into account magnetospheric substorm evolution of plasma energy accumulation and release, the largest wind amplitude at the recovery phase is a fascinating result. The results are the first detailed investigation of the magnetosphere-ionosphere-thermosphere coupled system at the substorm recovery phase using comprehensive data sets of solar wind, geomagnetic field, auroral pattern, and FPI-derived wind. This study used three events in November 2010 and January 2012, particularly focusing on the wind signatures associated with the auroral morphology, and found three specific features: (1) wind fluctuations that were isolated at the edge and/or in the darker area of an auroral patch with the largest vertical amplitude up to about 20 m/s and with the longest oscillation period about 10 min, (2) when the convection electric field was smaller than 15 mV/m, and (3) wind fluctuations that were accompanied by pulsating aurora. This approach suggests that the energy dissipation to produce the wind fluctuations is localized in the auroral pattern. Effects of the altitudinal variation in the volume emission rate were investigated to evaluate the instrumental artifact due to vertical wind shear. The small electric field values suggest weak contributions of the Joule heating and Lorentz force processes in wind fluctuations. Other unknown mechanisms may play a principal role at the recovery phase.

  7. Average thermospheric wind patterns over the polar regions, as observed by CHAMP

    Directory of Open Access Journals (Sweden)

    H. Lühr

    2007-06-01

    Full Text Available Measurements of the CHAMP accelerometer are utilized to investigate the average thermospheric wind distribution in the polar regions at altitudes around 400 km. This study puts special emphasis on the seasonal differences in the wind patterns. For this purpose 131 days centered on the June solstice of 2003 are considered. Within that period CHAMP's orbit is precessing once through all local times. The cross-track wind estimates of all 2030 passes are used to construct mean wind vectors for 918 equal-area cells. These bin averages are presented in corrected geomagnetic coordinates. Both hemispheres are considered simultaneously providing summer and winter responses for the same prevailing geophysical conditions. The period under study is characterized by high magnetic activity (Kp=4− but moderate solar flux level (F10.7=124. Our analysis reveals clear wind features in the summer (Northern Hemisphere. Over the polar cap there is a fast day-to-night flow with mean speeds surpassing 600 m/s in the dawn sector. At auroral latitudes we find strong westward zonal winds on the dawn side. On the dusk side, however, an anti-cyclonic vortex is forming. The dawn/dusk asymmetry is attributed to the combined action of Coriolis and centrifugal forces. Along the auroral oval the sunward streaming plasma causes a stagnation of the day-to-night wind. This effect is particularly clear on the dusk side. On the dawn side it is evident only from midnight to 06:00 MLT. The winter (Southern Hemisphere reveals similar wind features, but they are less well ordered. The mean day-to-night wind over the polar cap is weaker by about 35%. Otherwise, the seasonal differences are mainly confined to the dayside (06:00–18:00 MLT. In addition, the larger offset between geographic and geomagnetic pole in the south also causes hemispheric differences of the thermospheric wind distribution.

  8. Polygonal terrains on Mars

    Directory of Open Access Journals (Sweden)

    Pedro Pina

    2009-06-01

    Full Text Available The presence of water ice on Mars is well established. Some featureson the planet point to the occurrence of processes similar to those that take place in periglacial areas of Earth. One of the clues for this is the existence of small-scale polygonal terrains. In this paper, we present a methodology that aims at the automated identification of polygonal patterns on high-spatial resolution images of the surface of Mars. In the context of the research project TERPOLI, this step will be complemented with a full characterization, in both geometric and topological terms, of thenetworks detected. In this manner, we hope to collect data that will lead to a better understanding of the conditions of formation of the polygons, and of their temporal evolution; namely, we intend to identify different groups of polygons and to compare them with terrestrial examples.

  9. The politics of Mars

    Science.gov (United States)

    Schmitt, Harrison H.

    1986-01-01

    A discussion is presented comparing past and present major accomplishments of the U.S. and the Soviet Union in space. It concludes that the Soviets are presently well ahead of the U.S. in several specific aspects of space accomplishment and speculates that the Soviet strategy is directed towards sending a man to the vicinity of Mars by the end of this century. A major successful multinational space endeavor, INTELSAT, is reviewed and it is suggested that the manned exploration of Mars offers a unique opportunity for another such major international cooperative effort. The current attitude of U.S. leadership and the general public is assessed as uniformed or ambivalent about the perceived threat of Soviet dominance in space.

  10. Geophysics of Mars

    Science.gov (United States)

    Wells, R. A.

    1979-01-01

    A physical model of Mars is presented on the basis of light-scattering observations of the Martian atmosphere and surface and interior data obtained from observations of the geopotential field. A general description of the atmosphere is presented, with attention given to the circulation and the various cloud types, and data and questions on the blue haze-clearing effect and the seasonal darkening wave are summarized and the Mie scattering model developed to explain these observations is presented. The appearance of the planet from earth and spacecraft through Mariner 9 is considered, and attention is given to the preparation of topographical contour maps, the canal problem and large-scale lineaments observed from Mariner 9, the gravity field and shape of the planet and the application of Runcorn's geoid/convection theory to Mars. Finally, a summary of Viking results is presented and their application to the understanding of Martian geophysics is discussed.

  11. Exospheres and Energetic Neutral Atoms of Mars, Venus and Titan

    Science.gov (United States)

    Futaana, Yoshifumi; Chaufray, Jean-Yves; Smith, H. Todd; Garnier, Philippe; Lichtenegger, Herbert; Delva, Magda; Gröller, Hannes; Mura, Alessandro

    Our understanding of the upper atmosphere of unmagnetized bodies such as Mars, Venus and Titan has improved significantly in this decade. Recent observations by in situ and remote sensing instruments on board Mars Express, Venus Express and Cassini have revealed characteristics of the neutral upper atmospheres (exospheres) and of energetic neutral atoms (ENAs). The ENA environment in the vicinity of the bodies is by itself a significant study field, but ENAs are also used as a diagnostic tool for the exosphere and the interaction with the upstream plasmas. Synergy between theoretical and modeling work has also improved considerably. In this review, we summarize the recent progress of our understanding of the neutral environment in the vicinity of unmagnetized planets.

  12. Organics on Mars?

    Science.gov (United States)

    ten Kate, Inge L

    2010-01-01

    Organics are expected to exist on Mars based on meteorite infall, in situ production, and any possible biological sources. Yet they have not been detected on the martian surface; are they there, or are we not capable enough to detect them? The Viking gas chromatograph-mass spectrometer did not detect organics in the headspace of heated soil samples with a detection limit of parts per billion. This null result strongly influenced the interpretation of the reactivity seen in the Viking biology experiments and led to the conclusion that life was not present and, instead, that there was some chemical reactivity in the soil. The detection of perchlorates in the martian soil by instruments on the Phoenix lander and the reports of methane in the martian atmosphere suggest that it may be time to reconsider the question of organics. The high-temperature oxidizing properties of perchlorate will promote combustion of organics in pyrolytic experiments and may have affected the ability of both Phoenix's organic analysis experiment and the Viking mass spectrometer experiments to detect organics. So the question of organics on Mars remains open. A primary focus of the upcoming Mars Science Laboratory will be the detection and identification of organic molecules by means of thermal volatilization, followed by gas chromatography-mass spectrometry--as was done on Viking. However, to enhance organic detectability, some of the samples will be processed with liquid derivatization agents that will dissolve organics from the soil before pyrolysis, which may separate them from the soil perchlorates. Nonetheless, the problem of organics on Mars is not solved, and for future missions other organic detection techniques should therefore be considered as well.

  13. Meteorites from Mars

    Science.gov (United States)

    Grady, M.; Murdin, P.

    2002-01-01

    The SNC METEORITES, named after the initials of the first discovered members (Shergotty, Nakhla and Chassigny), are a group of stony meteorites that are thought to come from Mars, rather than the asteroid belt. They are all igneous rocks (i.e. formed by crystallizing from molten material) and are distinguished from other meteorites by their ages, which are as low as 165 million years old. A young...

  14. Chemical Thermodynamics on Mars

    Science.gov (United States)

    Selco, Jodye I.

    1995-07-01

    This seven question take-home exam guides the students through a marathon problem to arrive at a single answer to the overall question: "How sensitive a probe do you need in order to detect signs of "life" (methane produced by bacteria instead of by chemical equilibrium) on Mars". This exam was originally written to correspond to chapters four through seven in Ira Levine's Physical Chemistry, 3rd edition, McGraw Hill, New York, 1988.

  15. Mars Aeronomy Explorer (MAX): Study Employing Distributed Micro-Spacecraft

    Science.gov (United States)

    Shotwell, Robert F.; Gray, Andrew A.; Illsley, Peter M.; Johnson, M.; Sherwood, Robert L.; Vozoff, M.; Ziemer, John K.

    2005-01-01

    An overview of a Mars Aeronomy Explorer (MAX) mission design study performed at NASA's Jet Propulsion Laboratory is presented herein. The mission design consists of ten micro-spacecraft orbiters launched on a Delta IV to Mars polar orbit to determine the spatial, diurnal and seasonal variation of the constituents of the Martian upper atmosphere and ionosphere over the course of one Martian year. The spacecraft are designed to allow penetration of the upper atmosphere to at least 90 km. This property coupled with orbit precession will yield knowledge of the nature of the solar wind interaction with Mars, the influence of the Mars crustal magnetic field on ionospheric processes, and the measurement of present thermal and nonthermal escape rates of atmospheric constituents. The mission design incorporates alternative design paradigms that are more appropriate for-and in some cases motivate-distributed micro-spacecraft. These design paradigms are not defined by a simple set of rules, but rather a way of thinking about the function of instruments, mission reliability/risk, and cost in a systemic framework.

  16. Hygroscopic Salts on Mars

    Science.gov (United States)

    Melchiorri, R.; Davila, A. F.; Chittenden, J.; Haberle, R. M.

    2008-12-01

    We present preliminary results on the influence of a salt-rich regolith in the water cycle of Mars. Global climate modeling shows that the relative humidity on the Martian surface often reaches values above the deliquescence point of salts that are common components of the regolith. At the deliquescence point, these salts will absorb atmospheric water vapor and form a saturated, transient liquid solution that is stable under a range of temperatures. If atmospheric temperatures fall below the eutectic point of the solution, the later will freeze in the pore space of the regolith, thereby resulting in a net transport of water from the vapor phase in the atmosphere, to the solid state in the regolith. This simple model partially accounts for some the distribution of water on the Martian surface as revealed by Mars Odyssey, in particular, we find that: even though the Cl and surface water distributions detected by HEND/ODYSSEY are highly correlated, salt deliquescence under the the present atmospheric conditions does not explain the overall distribution of water in the near surface regolith. However deliquescence of salt-rich soils could be an important contributor to the distribution of water in the regolith at high obliquity. In that scenario the water in the near-surface regolith would be the remnant of high obliquity conditions salt deliquescence is still active in different regions on Mars today, and it should be introduced as a parameter in the modern GCMs as a new ground/atmosphere interaction

  17. Exobiological exploration of Mars

    Science.gov (United States)

    Klein, H. P.; Devincenzi, D. L.

    1995-01-01

    Of all the other planets in the solar system, Mars remains the most promising for further elucidating concepts about chemical evolution and the origin of life. Strategies were developed to pursue three exobiological objectives for Mars exploration: determining the abundance and distribution of the biogenic elements and organic compounds, detecting evidence of an ancient biota on Mars, and determining whether indigenous organisms exist anywhere on the planet. The three strategies are quite similar and, in fact, share the same sequence of phases. In the first phase, each requires global reconnaissance and remote sensing by orbiters to select sites of interest for detailed in situ analyses. In the second phase, lander missions are conducted to characterize the chemical and physical properties of the selected sites. The third phase involves conducting 'critical' experiments at sites whose properties make them particularly attractive for exobiology. These critical experiments would include, for example, identification of organics, detection of fossils, and detection of extant life. The fourth phase is the detailed analysis of samples returned from these sites in Earth-based laboratories to confirm and extend previous discoveries. Finally, in the fifth phase, human exploration is needed to establish the geological settings for the earlier findings or to discover and explore sites that are not accessible to robotic spacecraft.

  18. Mars Rocket Propulsion System

    Science.gov (United States)

    Zubrin, Robert; Harber, Dan; Nabors, Sammy

    2008-01-01

    A report discusses the methane and carbon monoxide/LOX (McLOx) rocket for ascent from Mars as well as other critical space propulsion tasks. The system offers a specific impulse over 370 s roughly 50 s higher than existing space-storable bio-propellants. Current Mars in-situ propellant production (ISPP) technologies produce impure methane and carbon monoxide in various combinations. While separation and purification of methane fuel is possible, it adds complexity to the propellant production process and discards an otherwise useful fuel product. The McLOx makes such complex and wasteful processes unnecessary by burning the methane/CO mixtures produced by the Mars ISPP systems without the need for further refinement. Despite the decrease in rocket-specific impulse caused by the CO admixture, the improvement offered by concomitant increased propellant density can provide a net improvement in stage performance. One advantage is the increase of the total amount of propellant produced, but with a decrease in mass and complexity of the required ISPP plant. Methane/CO fuel mixtures also may be produced by reprocessing the organic wastes of a Moon base or a space station, making McLOx engines key for a human Lunar initiative or the International Space Station (ISS) program. Because McLOx propellant components store at a common temperature, very lightweight and compact common bulkhead tanks can be employed, improving overall stage performance further.

  19. Observing Magnetic and Current Profiles of the Night side and Terminator of Mars through the Mars Global Surveyor Data

    Science.gov (United States)

    Ponce, N.; Fillingim, M. O.; Fogle, A. L.

    2014-12-01

    Mars has no global magnetic field. Changes in the solar wind and interplanetary magnetic field can impact the upper atmosphere and induce currents in the ionosphere of Mars. During aerobraking maneuvers, Mars Global Surveyor (MGS) made over 1000 passes through Mars's ionosphere. During these passes, MGS measured the local magnetic field. From these measurements, we can determine the ionospheric currents. We restrict our analysis to passes where the radial component of the magnetic field is nearly zero. This restriction, along with some assumptions about the gradients in the magnetic field, allows us to estimate the horizontal ionospheric currents. Additionally, we focus on the magnetic field data acquired over regions above negligible crustal magnetic fields in order to simplify the analysis. At a maximum altitude of 250 km, the Mars map was segmented to 30 by 30 degrees east longitude and latitude for analysis. We find that on the night side, where the solar zenith angle (SZA) lies between 130 to 180 degrees, only 4% of the data (out of a total of 52 profiles) is usable for computing currents, that is the radial component of the magnetic field is nearly zero. We also find that near the terminator, where the SZA lies between 50 to 130 degrees, an average of 2% of the magnetic field profiles (out of 1905) are usable to compute currents. This implies that currents are rarely horizontal (as required by our assumptions) in these regions. The currents computed from these profiles can give us insights into how the changing solar wind and interplanetary magnetic field can affect the upper atmosphere of Mars. For example, induced currents can lead to Joule heating of the atmosphere potentially modifying the neutral dynamics.

  20. Variability of Jovian ion winds: an upper limit for enhanced Joule heating

    Directory of Open Access Journals (Sweden)

    M. B. Lystrup

    2007-05-01

    Full Text Available It has been proposed that short-timescale fluctuations about the mean electric field can significantly increase the upper atmospheric energy inputs at Jupiter, which may help to explain the high observed thermospheric temperatures. We present data from the first attempt to detect such variations in the Jovian ionosphere. Line-of-sight ionospheric velocity profiles in the Southern Jovian auroral/polar region are shown, derived from the Doppler shifting of H3+ infrared emission spectra. These data were recently obtained from the high-resolution CSHELL spectrometer at the NASA Infrared Telescope Facility. We find that there is no variability within this data set on timescales of the order of one minute and spatial scales of 640 km, putting upper limits on the timescales of fluctuations that would be needed to enhance Joule heating.

  1. Guidelines for 2007 MARS exercise

    CERN Multimedia

    HR Department

    2007-01-01

    Following the introduction of the new Merit Appraisal and Recognition Scheme (MARS), full details of the scheme are now available via the HR Department's homepage or directly on the Department's MARS web page: in English: http://humanresources.web.cern.ch/HumanResources/internal/personnel/pmd/cr/MARS.asp or French: http://humanresources.web.cern.ch/humanresources/internal/personnel/pmd/cr/mars_fr.asp You will find on this page: 'Introduction to MARS' with detailed information presented in Frequently Asked Questions; these include the MARS timetable for proposals and decisions; 'Regulations' with links to the scheme's statutory documents; 'Procedures and Forms' and 'Useful Information' with links to all the relevant documentation; these include the mandates of the Senior Staff Advisory Committee (SSAC) and the Technical Engineers and Administrative Careers Committee (TEACC). HR Department Tel. 73566

  2. Study of magnetic activity effects on the thermospheric winds in the low ionosphere. Master`s thesis

    Energy Technology Data Exchange (ETDEWEB)

    Davila, R.C.

    1994-09-01

    The purpose of this thesis is to examine the effects of magnetic activity on the low latitude F-region thermospheric winds. The F-region (120-1600 km) is a partially ionized medium where O+ and O are the major ion and neutral species, respectively. The thermospheric winds at these altitudes are driven primarily by pressure gradient forces resulting from the solar heating during the day and cooling at night. For this study, the author used measured Fabry-Perot Interferometer (FPI) winds at Arequipa (16.5 deg S, 71.5 deg W) and measured FPI and incoherent Scatter Radar (ISR) winds at Arecibo (18.6 deg N, 66.8 deg W).

  3. Seasonal Transport in Mars' Mesosphere revealed by Nitric Oxide Nightglow vertical profiles and global images from IUVS/MAVEN

    Science.gov (United States)

    Stiepen, Arnaud; Stewart, Ian; Jain, Sonal; Schneider, Nicholas; Deighan, Justin; Gonzàlez-Galindo, Francisco; Gérard, Jean-Claude; Stevens, Michael; Bougher, Stephen; Milby, Zachariah; Evans, Scott; Chaffin, Michael; McClintock, William; Clarke, John; Holsclaw, Greg; Montmessin, Franck; Lefèvre, Franck; Lo, Daniel; Jakosky, Bruce

    2017-04-01

    We analyze the ultraviolet nightglow in the atmosphere of Mars through Nitric Oxide (NO) δ and γ bands emissions. On the dayside thermosphere of Mars, solar extreme ultraviolet radiation partly dissociates CO2 and N2 molecules. O(3P) and N(4S) atoms are carried by the day-to-night hemispheric transport. They preferentially descend in the nightside mesosphere in the winter hemisphere, where they can radiatively recombine to form NO(C2Π). The excited molecules promptly relax by emitting photons in the UV δ bands and in the γ bands through cascades via the A2Σ, v' = 0 state. These emissions are thus indicators of the N and O atom fluxes transported from the dayside to Mars' nightside and the winter descending circulation pattern from the nightside thermosphere to the mesosphere (e.g. Bertaux et al., 2005 ; Bougher et al., 1990 ; Cox et al., 2008 ; Gagné et al., 2013 ; Gérard et al., 2008 ; Stiepen et al., 2015). Observations of these emissions have been accumulated on a large dataset of nightside disk images and vertical profiles obtained at the limb by the Imaging Ultraviolet Spectrograph (IUVS, McClintock et al., 2015) instrument when the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft is at its apoapsis and its periapsis phases along its orbit, respectively. We present discussion on the variability in the brightness, altitude and topside scale height of the emission with season, geographical position and local time and possible interpretation for local and global changes in the mesosphere dynamics. IUVS images and limb scans reveal unexpected complex structure of the emission. The brightest emission is observed close to the winter pole. The emission is also surprisingly more intense in some sectors located close to the equator : at 120˚ and 150˚ longitude. Observations also reveal spots and streaks, indicating irregularities in the wind circulation pattern and possible impact of waves and tides. The disk images and limb profiles are compared to

  4. Radar Sounding of Mars with MARSIS

    Science.gov (United States)

    Plaut, J. J.; Picardi, G.; Orosei, R.; Gurnett, D. A.

    2009-12-01

    MARSIS, the Mars Advanced Radar for Subsurface and Ionospheric Sounding, is a radar sounder that has been observing Mars from the Mars Express orbiter since June 2005. MARSIS works in the range of 1.3 to 5.5 MHz, and includes significant onboard data summing. MARSIS also operates in an Active Ionospheric Sounding mode down to 0.1 MHz to capture echoes from the topside of the ionosphere. MARSIS signals easily penetrate the polar layered deposits (PLD), usually to their basal contact with the substrate. The typically strong echo return from the lower interface of the PLD indicates that only minor attenuation of the radar signal is occurring within the PLD, implying a composition of nearly pure water ice. MARSIS data have been used to map the bed of the polar deposits to their maximum depth of over 3.5 km in the south. In the north, MARSIS delineates the extent of the “basal unit,” a sediment-laden icy layer that makes up more than a third of the total volume of the topographic cap. In both polar regions, the bed topography does not display a regional-scale deflection that might be expected from a flexural response to the PLD load, indicating a thick elastic lithosphere in these regions. Subsurface interfaces in the low latitudes of Mars are also being mapped by MARSIS, in the equatorial Medusae Fossae Formation. MARSIS has not detected any unambiguous evidence for sizable shallow aquifers. While it is possible that such features exist, the lack of detection more likely indicates that liquid water is not abundant in the shallow (< several km) subsurface of Mars. However, water ice is abundant in the polar regions, including a large area surrounding the polar layered deposits that is associated with the Dorsa Argentea Formation. In addition, analysis of the MARSIS surface echo strength suggests that a substantial fraction of the upper km of the subsurface of the northern plains may be ice-rich. In its ionospheric mode, MARSIS has characterized the complex structure

  5. Investigating the Role of Sub-Auroral Polarization Stream Electric Field in Coupled Magnetosphere-Ionosphere-Thermosphere Systemwide Processes

    Science.gov (United States)

    2017-04-04

    AFRL-AFOSR-JP-TR-2017-0028 Investigating the role of sub-auroral polarization stream electric field in coupled magnetosphere-ionosphere-thermosphere...systemwide processes Ildiko Horvath THE UNIVERSITY OF QUEENSLAND Final Report 04/04/2017 DISTRIBUTION A: Distribution approved for public release. AF...ABSTRACT Unclassified c. THIS PAGE Unclassified REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188 The public reporting burden for this

  6. Upper Kenai Corridor Study

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Upper Kenai Corridor study describes and evaluates the Upper Kenai River and the land which embraces it. It also places the river corridor in its regional...

  7. Variability of the Martian thermosphere during eight Martian years as simulated by a ground-to-exosphere global circulation model

    Science.gov (United States)

    González-Galindo, F.; López-Valverde, M. A.; Forget, F.; García-Comas, M.; Millour, E.; Montabone, L.

    2015-11-01

    Using a ground-to-exosphere general circulation model for Mars we have simulated the variability of the dayside temperatures at the exobase during eight Martian years (MY, from MY24 to MY31, approximately from 1998 to 2013), taking into account the observed day-to-day solar and dust load variability. We show that the simulated temperatures are in good agreement with the exospheric temperatures derived from Precise Orbit Determination of Mars Global Surveyor. We then study the effects of the solar variability and of two planetary-encircling dust storms on the simulated temperatures. The seasonal effect produced by the large eccentricity of the Martian orbit translates in an aphelion-to-perihelion temperature contrast in every simulated year. However, the magnitude of this seasonal temperature variation is strongly affected by the solar conditions, ranging from 50 K for years corresponding to solar minimum conditions to almost 140 K during the last solar maximum. The 27 day solar rotation cycle is observed on the simulated temperatures at the exobase, with average amplitude of the temperature oscillation of 2.6 K but with a significant interannual variability. These two results highlight the importance of taking into account the solar variability when simulating the Martian upper atmosphere and likely have important implications concerning the atmospheric escape rate. We also show that the global dust storms in MY25 and MY28 have a significant effect on the simulated temperatures. In general, they increase the exospheric temperatures over the low latitude and midlatitude regions and decrease them in the polar regions.

  8. Lower-thermospheric wind fluctuations measured with an FPI during pulsating aurora at Tromsø, Norway

    Directory of Open Access Journals (Sweden)

    S. Oyama

    2010-10-01

    Full Text Available Simultaneous observations were conducted with a Fabry-Perot Interferometer (FPI at a wavelength of 557.7 nm, an all-sky camera at a wavelength of 557.7 nm, and the European Incoherent Scatter (EISCAT UHF radar during the Dynamics and Energetics of the Lower Thermosphere in Aurora 2 (DELTA-2 campaign in January 2009. This paper concentrated on two events during periods of pulsating aurora. The lower-thermospheric wind velocity measured with the FPI showed obvious fluctuations in both vertical and horizontal components. Of particular interest is that the location of the fluctuations was found in a darker area that appeared within the pulsating aurora. During the same time period, the EISCAT radar observed sporadic enhancements in the F-region backscatter echo power, which suggests the presence of low-energy electron (1 keV or lower precipitation coinciding with increase in amplitude of the electromagnetic wave (at the order of 10 Hz or higher. While we have not yet identified the dominant mechanism causing the fluctuations in FPI-derived wind velocity during the pulsating aurora, the frictional heating energy dissipated by the electric-field perturbations may be responsible for the increase in ionospheric thermal energy thus modifying the local wind dynamics in the lower thermosphere.

  9. MIPAS observations of longitudinal oscillations in the mesosphere and the lower thermosphere: climatology of odd-parity daily frequency modes

    Science.gov (United States)

    García-Comas, Maya; González-Galindo, Francisco; Funke, Bernd; Gardini, Angela; Jurado-Navarro, Aythami; López-Puertas, Manuel; Ward, William E.

    2016-09-01

    MIPAS global Sun-synchronous observations are almost fixed in local time. Subtraction of the descending and ascending node measurements at each longitude only includes the longitudinal oscillations with odd daily frequencies nodd from the Sun's perspective at 10:00. Contributions from the background atmosphere, daily-invariant zonal oscillations and tidal modes with even-parity daily frequencies vanish. We have determined longitudinal oscillations in MIPAS temperature with nodd and wavenumber k = 0-4 from the stratosphere to 150 km from April 2007 to March 2012. To our knowledge, this is the first time zonal oscillations in temperature have been derived pole to pole in this altitude range from a single instrument. The major findings are the detection of (1) migrating tides at northern and southern high latitudes; (2) significant k = 1 activity at extratropical and high latitudes, particularly in the Southern Hemisphere; (3) k = 3 and k = 4 eastward-propagating waves that penetrate the lower thermosphere with a significantly larger vertical wavelength than in the mesosphere; and (4) a migrating tide quasi-biennial oscillation in the stratosphere, mesosphere and lower thermosphere. MIPAS global measurements of longitudinal oscillations are useful for testing tide modeling in the mesosphere and lower thermosphere region and as a lower boundary for models extending higher up in the atmosphere.

  10. Study on Planetary Wave Propagation in the Lower Thermosphere using wind Measurements from Fabry-Perot Interferometers

    Science.gov (United States)

    Otoo Lomotey, Solomon; Meriwether, John; Buriti, Ricardo; Medeiros, Amauri; Paulino, Igo; Barros Silva, Diego

    2016-07-01

    This research is focused on the study of planetary wave propagation in the lower thermosphere. The Fabry-Perot Interferometer (FPI) is a passive optical sensing instrument used to estimate thermospheric winds and temperature. The data used in this paper were captured by the FPIs which are located at São João do Carirri (7.4°S, 36.5°W) and Cajazeiras (6.9ºS, 38.5ºW). The main objective of this research is looking for periodicities in the wind measurements with periods longer than few days in both component of the wind. This was done by using airglow emission of Atomic Oxygen OI630nm in the red line during the nighttime, i.e., from 20:00 to 03:00 local time (LT). Lomb-Scargle analysis was used to process the thermospheric winds and temperature. Phases (time of maximum) and amplitudes of these oscillations were estimated by using Least Square fitting method (LSF), almost all of periodicities propagation of planetary waves was above 2 days for the Zonal and Meriodional winds. A strong oscillation of quasi eight days were observed from September to December 2003

  11. Upper limb arterial thromboembolism

    DEFF Research Database (Denmark)

    Andersen, L V; Lip, Gregory Y.H.; Lindholt, J S;

    2013-01-01

    The aim of this review is to focus on risk factors, risk-modifying drugs and prognosis for upper limb arterial thromboembolism, and the relationship between upper limb arterial thromboembolism and atrial fibrillation (AF).......The aim of this review is to focus on risk factors, risk-modifying drugs and prognosis for upper limb arterial thromboembolism, and the relationship between upper limb arterial thromboembolism and atrial fibrillation (AF)....

  12. Magnetic Strips Preserve Record of Ancient Mars

    Science.gov (United States)

    1999-01-01

    the new crust that carry a fossil record of the past hundreds of million years of Earth's magnetic history, a finding that validated the once-controversial theory of plate tectonics. 'The discovery of this pattern on Mars could revolutionize current thinking of the red planet's evolution,' said Dr. Jack Connerney of NASA's Goddard Space Flight Center, Greenbelt, MD, an investigator on the Global Surveyor's magnetometer team. 'If the bands on Mars are an imprint of crustal spreading, they are a relic of an early era of plate tectonics on Mars. However, unlike on Earth, the implied plate tectonic activity on Mars is most likely extinct.' Alternate explanations for the banded structure may involve the fracturing and breakup of an ancient, uniformly magnetized crust due to volcanic activity or tectonic stresses from the rise and fall of neighboring terrain. 'Imagine a thin coat of dried paint on a balloon, where the paint is the crust of Mars,' explained Dr. Mario Acuna of Goddard, principal investigator on the Global Surveyor magnetometer. 'If we inflate the balloon further, cracks can develop in the paint, and the edges of the cracks will automatically have opposite polarities, because nature does not allow there to be a positive pole without a negative counterpart.' Peer-reviewed research based on the observations will be published in the April 30 issue of the journal Science. The observations of the so-called magnetic stripes were made possible because of Mars Global Surveyor's special aerobraking orbit. This process of dipping into the upper atmosphere of Mars to gradually shape the probe's orbit into a circle was extended due to a problem with a solar panel on the spacecraft. The lowest point of each elliptically shaped orbit curved below the planet's ionosphere, allowing the magnetometer to obtain better-than-planned regional measurements of Mars. 'At its nominal orbit more than 200 miles high, the instruments face too much magnetic interference, and they do not

  13. A Mars Riometer

    Science.gov (United States)

    Fry, C. D.; Rosenberg, T. J.; Lutz, L.; Detrick, D. L.; Weatherwax, A. T.; Knouse, E.; Breden, H.; Giganti, J.

    1998-09-01

    The Planetary Surface Instruments Workshop (Meyer et al., LPI Tech. Rpt. 95-05, 1995) identified surface-based radio science instruments as key tools for observing Mars' middle atmosphere, its ionosphere and solar-wind interaction. For example, Mars has a substantial daytime ionosphere, and some important features of the Martian ionosphere can only be observed from below. One instrument, the Relative Ionospheric Opacity Meter (Riometer), is expected to work well on Mars (Detrick et al., PSS, 45, p. 289, 1997). In the past, the size, power requirements and complexity of these instruments have argued against including them on a lander or rover mission, in spite of the potentially rich science return. We describe the development of a miniature radio receiver designed to operate as a Riometer. The development of this receiver was funded by NASA as an enabling technology for future planetary radio science missions. Our receiver includes features that are desirable for extended autonomous operation: low power consumption, wide dynamic range and linearity, computer command and data interface, and the ability to be remotely reconfigured. The receiver design provides significant improvements over previous implementations used in terrestrial riometry. The high degree of system linearity, combined with a digital feedback loop (including a low-duty calibration cycle), allows a longer measurement time. We were able to significantly miniaturize the receiver by using modern, low-power electronic components that have come on the market. We also implemented several of the subsystems in a field-programmable gate array, including the receiver detector, the control logic, and the data acquisition and processing blocks. Considerable efforts were made to eliminate or minimize RF noise and spurious emissions generated by the receiver's digital circuitry. Results of laboratory and field tests are presented and discussed.

  14. Un mar compartido

    OpenAIRE

    2008-01-01

    Existen pocos ámbitos más reveladores que el mar para entender las virtudes de la cooperación internacional en materia científica. En las ciencias marinas esta cooperación es más que deseable: es imprescindible para poder contestar preguntas relacionadas con el movimiento de las corrientes, el aporte de los ríos, los ciclos migratorios de las especies, las pesquerías, etc. Se analiza la importancia de los proyectos conjuntos donde participaron países latinoamericanos, algunos con éxitos, y so...

  15. Mars Rover RTG Study

    Energy Technology Data Exchange (ETDEWEB)

    Schock, Alfred

    1989-08-25

    This report summarizes the results of a Radioisotope Thermoelectric Generator (RTG) design study conducted by Fairchild Space Company at the direction of the U.S. Department of Energy's Office of SpecialApplications, in suppport of the Mars Rover and Sample Return mission under investigation at NASA's Jet Propulsion Laboratory. The report is a rearranged, updated, and significantly expanded amalgam of three interrelated papers presented at the 24th Intersocity Energy Conversion Engineering Conference (IECEC) at Arlington, Virginia, on August 10, 1989.

  16. The salts of Mars

    Science.gov (United States)

    Clark, B. C.; Van Hart, D. C.

    1981-01-01

    Salt compounds are apparently an important component of the fine-grained regolith on Mars. Salt enrichment may be explained either as a secondary concentration of chemical weathering products or as direct incorporation of planetary released volatiles. Geochemical measurements and chemical relationships constrain the salt species and resultant physicochemical consequences. A likely assemblage is dominated by (Mg,Na)SO4, NaCl, and (Mg,Ca)CO3. Formation of brine in equilibrium with such a salt mixture is unlikely under the temperature and water-vapor restrictions prevalent over most, if not all, of the Martian surface. Acidic conditions, accompanying salt formation, favor the preferential destruction of susceptible igneous minerals.

  17. Mars Surface Simulations

    Science.gov (United States)

    Nørnberg, Per; Merrison, Jonathan P.; Gunnlaugsson, Haraldur P.

    2010-05-01

    Laboratory simulations of the Martian surface are of importance to broaden scientific understanding of the physical processes, but also in order to develop the technology necessary for exploration of the planet. The Mars Simulation Laboratory at Aarhus University [1] has been involved in such simulations for around ten years and has developed several experimental facilities for carrying out science or instrument testing under conditions similar to those at the Martian surface, specifically low pressure, low temperature and importantly recreating the wind flow environment and dust suspension (reproducing the Martian dusty aerosol) using Mars analogue material [2]. The science involved in this simulation work has covered a broad spectrum including, erosion induced mineralogy/chemistry, particulate electrification, magnetic properties of Martian dust, biological survival, UV induced chemistry/mineralogy (using a solar simulator), adhesion/cohesion processes and the wind driven transport of dust and sand [3,4]. With regard to technology the wind tunnel facilities have been used in the development of the latest wind and dust sensing instrumentation [5,6]. With support from the European Space Agency (ESA) and Danish national funding an advanced Mars simulation facility has recently been constructed (2009). This wind tunnel facility has a cross section of 2 x 1 m and a length of 8 m, a temperature range down to below -120C, wind speeds in excess of 20m/s, and automated dust control. With a range of (specialised) sensing instrumentation it provides the opportunity to perform a new generation of scientific experiments and allow testing and technology development in the most realistic and rigorous environment. As well as being available for the space agencies, this facility will be open to all potential scientific collaborators. Also European planetary scientists may benefit from support through the EU Europlanet FP7 networking programme. For more information on access

  18. MARS15 overview

    Energy Technology Data Exchange (ETDEWEB)

    Mokhov, N.V.; Striganov, S.I.; /Fermilab

    2007-01-01

    MARS15 is a Monte Carlo code for inclusive and exclusive simulation of three-dimensional hadronic and electromagnetic cascades, muon, heavy-ion, and low-energy neutron transport in accelerator, detector, spacecraft, and shielding components in the energy range from a fraction of an electronvolt up to 100 TeV. Main features of the code are described in this paper with a focus on recent developments and benchmarking. Newest developments concern inclusive and exclusive nuclear event generators, extended particle list in both modes, heavy-ion capability, electromagnetic interactions, enhanced geometry, tracking, histogramming and residual dose modules, improved graphical-user interface, and other external interfaces.

  19. BUILDING ON THE MARS PLANET

    Directory of Open Access Journals (Sweden)

    Valeriy Pershakov

    2012-09-01

    Full Text Available  The main task is the terraforming of the Mars planet. Nowadays it is a very important task, because there are a lot of problems on the planet Earth, which deals with the exhaustion of natural resources. The solution is in the colonizing and building on the Mars planet.

  20. Monitoring Mars for Electrostatic Disturbances

    Science.gov (United States)

    Compton, D.

    2011-01-01

    The DSN radio telescope DSS-13 was used to monitor Mars for electrostatic discharges from 17 February to 11 April, 2010, and from 19 April to 4 May, 2011, over a total of 72 sessions. Of these sessions, few showed noteworthy results and no outstanding electrostatic disturbances were observed on Mars from analyzing the kurtosis of radio emission from Mars. Electrostatic discharges on mars were originally detected in June of 2006 by Ruf et al. using DSS-13. he kurtosis (normalized fourth moment of the electrical field strength) is sensitive to non-thermal radiation. Two frequencies bands, either 2.4 and 8.4 GHz or 8.4 and 32 GHz were used. The non-thermal radiation spectrum should have peaks at the lowest three modes of the theoretical Schumann Resonances of Mars. The telescope was pointed away from Mars every 5 minutes for 45 seconds to confirm if Mars was indeed the sources of any events. It was shown that by including a down-link signal in one channel and by observing when the kurtosis changed as the telescope was pointed away from the source that the procedure can monitor Mars without the need of extra equipment monitoring a control source.

  1. New results on equatorial thermospheric winds and temperatures from Ethiopia, Africa

    Science.gov (United States)

    Tesema, Fasil; Mesquita, Rafael; Meriwether, John; Damtie, Baylie; Nigussie, Melessew; Makela, Jonathan; Fisher, Daniel; Harding, Brian; Yizengaw, Endawoke; Sanders, Samuel

    2017-03-01

    Measurements of equatorial thermospheric winds, temperatures, and 630 nm relative intensities were obtained using an imaging Fabry-Perot interferometer (FPI), which was recently deployed at Bahir Dar University in Ethiopia (11.6° N, 37.4° E, 3.7° N magnetic). The results obtained in this study cover 6 months (53 nights of useable data) between November 2015 and April 2016. The monthly-averaged values, which include local winter and equinox seasons, show the magnitude of the maximum monthly-averaged zonal wind is typically within the range of 70 to 90 ms-1 and is eastward between 19:00 and 21:00 LT. Compared to prior studies of the equatorial thermospheric wind for this local time period, the magnitude is considerably weaker as compared to the maximum zonal wind speed observed in the Peruvian sector but comparable to Brazilian FPI results. During the early evening, the meridional wind speeds are 30 to 50 ms-1 poleward during the winter months and 10 to 25 ms-1 equatorward in the equinox months. The direction of the poleward wind during the winter months is believed to be mainly caused by the existence of the interhemispheric wind flow from the summer to winter hemispheres. An equatorial wind surge is observed later in the evening and is shifted to later local times during the winter months and to earlier local times during the equinox months. Significant night-to-night variations are also observed in the maximum speed of both zonal and meridional winds. The temperature observations show the midnight temperature maximum (MTM) to be generally present between 00:30 and 02:00 LT. The amplitude of the MTM was ˜ 110 K in January 2016 with values smaller than this in the other months. The local time difference between the appearance of the MTM and a pre-midnight equatorial wind was generally 60 to 180 min. A meridional wind reversal was also observed after the appearance of the MTM (after 02:00 LT). Climatological models, HWM14 and MSIS-00, were compared to the

  2. Numerical simulations of thermospheric dynamics: divergence as a proxy for vertical winds

    Directory of Open Access Journals (Sweden)

    S. L. Cooper

    2009-06-01

    Full Text Available A local scale, time dependent three-dimensional model of the neutral thermosphere was used to test the applicability of two previously published empirical relations between thermospheric vertical wind and velocity divergence, i.e., those due to Burnside et al. (1981 and Brekke (1997. The model self-consistently solves for vertical winds driven by heat and momentum deposited into the neutral atmosphere by high latitude ion convection. The Brekke condition accurately mimicked the overall "shape" of the three-dimensional model vertical wind field although, as written, it consistently overestimated the vertical wind magnitude by a factor of approximately 5/3, for the heating scenarios that we considered. This same general behavior was observed regardless of whether the forcing was static or rapidly changing with time. We discuss the likely reason for the Brekke condition overestimating the magnitude of our vertical winds, and suggest an alternative condition that should better describe vertical winds that are driven by local heating. The applicability of the Burnside condition was, by contrast, quite variable. During static heating, both the magnitude and the sign of the model vertical winds were predicted reliably at heights above those of maximum energy and momentum deposition per unit mass. However, below the thermal forcing, the Burnside condition predicted vertical winds of the wrong sign. It also introduced significant artefacts into the predicted vertical wind field when the forcing changed suddenly with time. If these results are of general applicability (which seems likely, given the way these relations are derived then the Burnside condition could usually be used safely at altitudes above hmF2. But it should be avoided below this height at all times, and even at high altitudes during periods of dynamic forcing. While the Brekke condition (or our modified version of it could likely be used in all circumstances

  3. New results on equatorial thermospheric winds and the midnight temperature maximum

    Energy Technology Data Exchange (ETDEWEB)

    Meriwether, J.; Faivre, M.; Fesen, C. [Clemson Univ., SC (United States). Dept. of Physics and Astronomy; Sherwood, P. [Interactive Technology, Waban, MA (United States); Veliz, O. [Inst. Geofisica del Peru, Lima (Peru). Radio Observatorio de Jicamarca

    2008-07-01

    Optical observations of thermospheric winds and temperatures determined with high resolution measurements of Doppler shifts and Doppler widths of the OI 630-nm equatorial nightglow emission have been made with improved accuracy at Arequipa, Peru (16.4 S, 71.4 W) with an imaging Fabry-Perot interferometer. An observing procedure previously used at Arecibo Observatory was applied to achieve increased spatial and temporal sampling of the thermospheric wind and temperature with the selection of eight azimuthal directions, equally spaced from 0 to 360 , at a zenith angle of 60 . By assuming the equivalence of longitude and local time, the data obtained using this technique is analyzed to determine the mean neutral wind speeds and mean horizontal gradients of the wind field in the zonal and meridional directions. The new temperature measurements obtained with the improved instrumental accuracy clearly show the midnight temperature maximum (MTM) peak with amplitudes of 25 to 200 K in all directions observed for most nights. The horizontal wind field maps calculated from the mean winds and gradients show the MTM peak is always preceded by an equatorward wind surge lasting 1-2 h. The results also show for winter events a meridional wind abatement seen after the MTM peak. On one occasion, near the September equinox, a reversal was observed during the poleward transit of the MTM over Arequipa. Analysis inferring vertical winds from the observed convergence yielded inconsistent results, calling into question the validity of this calculation for the MTM structure at equatorial latitudes during solar minimum. Comparison of the observations with the predictions of the NCAR general circulation model indicates that the model fails to reproduce the observed amplitude by a factor of 5 or more. This is attributed in part to the lack of adequate spatial resolution in the model as the MTM phenomenon takes place within a scale of 300-500 km and {proportional_to}45 min in local time. The

  4. The 2009 Mars Telecommunications Orbiter

    Science.gov (United States)

    Wilson, G. R.; Depaula, R.; Diehl, R. E.; Edwards, C. D.; Fitzgerald, R. J.; Franklin, S. F.; Gibbs, R. G.; Kerridge, S. A.; Komarek, T. A.; Noreen, G. K.

    The first spacecraft with a primary function of providing communication links while orbiting a foreign planet has begun development for a launch in 2009. NASA's Mars Telecommunications Orbiter would use three radio bands to magnify the benefits of other future Mars missions and enable some types of missions otherwise impractical. It would serve as the Mars hub for a growing interplanetary Internet. And it would pioneer the use of planet-to-planet laser communications to demonstrate the possibility for even great networking capabilities in the future. During its nearly 10-year mission in orbit, Mars Telecommunications Orbiter would aid navigation of arriving spacecraft to their martian landing sites and monitor critical events during landings and orbit insertions. In addition, it would enable data-transmission volumes great enough to bring a virtual Mars presence to the public through a range of Internet and video features.

  5. Mars Express 10 years at Mars: Observations by the Mars Express Radio Science Experiment (MaRS)

    Science.gov (United States)

    Pätzold, M.; Häusler, B.; Tyler, G. L.; Andert, T.; Asmar, S. W.; Bird, M. K.; Dehant, V.; Hinson, D. P.; Rosenblatt, P.; Simpson, R. A.; Tellmann, S.; Withers, P.; Beuthe, M.; Efimov, A. I.; Hahn, M.; Kahan, D.; Le Maistre, S.; Oschlisniok, J.; Peter, K.; Remus, S.

    2016-08-01

    The Mars Express spacecraft is operating in Mars orbit since early 2004. The Mars Express Radio Science Experiment (MaRS) employs the spacecraft and ground station radio systems (i) to conduct radio occultations of the atmosphere and ionosphere to obtain vertical profiles of temperature, pressure, neutral number densities and electron density, (ii) to conduct bistatic radar experiments to obtain information on the dielectric and scattering properties of the surface, (iii) to investigate the structure and variation of the crust and lithosphere in selected target areas, (iv) to determine the mass, bulk and internal structure of the moon Phobos, and (v) to track the MEX radio signals during superior solar conjunction to study the morphology of coronal mass ejections (CMEs). Here we report observations, results and discoveries made in the Mars environment between 2004 and 2014 over almost an entire solar cycle.

  6. Intimations of water on Mars.

    Science.gov (United States)

    2000-08-01

    This photo essay contains images of Mars that propose evidence of the possible present or past existence of liquid water on Mars. Images were taken by the Mars Global Surveyor Mars Orbiter Camera. Images presented include: Polar Wall Pit region, consisting of gully landforms possibly caused by seepage and runoff of liquid water; Noachis Terra region, an area of gullies eroded into the wall of a meteor impact crater, where channels and related debris are seen, possibly formed by seepage, runoff, and debris flow; two images of Gorgonum Chaos region, one a series of troughs and layers of gullies and the other of gullies in a specific layer forming an alcove similar to an aquifer; Sirenum Fossae/Gorgonum Chaos mosaic of two images from this region of the southern hemisphere of Mars, showing 20 different channels coming down from a trough and their associated debris fans. Images and their enhancements are from NASA/JPL/Malin Space Science System.

  7. Mathematics and Mars Exploration

    Science.gov (United States)

    Velasco, M. P.; Usero, D.; Jiménez, S.; Aguirre, C.; Vázquez, L.

    2015-01-01

    In this study we consider modelization associated with study of solar radiation at the surface of Mars and the Martian atmosphere. In particular, we present elements concerning retrieval of the solar irradiance spectrum on the surface of Mars from data collected by arrays of photodiodes, such as those onboard the "Curiosity" MSL-rover and other missions currently under design. By using these techniques we are able to provide an approximate description of the expected measures. In this work we have also developed a new method of tomography-based signal analysis for detection of events in the Martian atmosphere boundary layer, such as dust devils. In general, this method enables detection of events that occur briefly in time and are localized in space. This tomographic method allows us to identify the presence of more dust devils than detected previously using the same data. Finally we show new scenarios of modelization through fractional differential equations associated with diffusion processes and nonlocal problems. Such approaches could be used to model complex Martian dynamics.

  8. Mars synthetic topographic mapping

    Science.gov (United States)

    Wu, S.S.C.

    1978-01-01

    Topographic contour maps of Mars are compiled by the synthesis of data acquired from various scientific experiments of the Mariner 9 mission, including S-band radio-occulation, the ultraviolet spectrometer (UVS), the infrared radiometer (IRR), the infrared interferometer spectrometer (IRIS) and television imagery, as well as Earth-based radar information collected at Goldstone, Haystack, and Arecibo Observatories. The entire planet is mapped at scales of 1:25,000,000 and 1:25,000,000 using Mercator, Lambert, and polar stereographic map projections. For the computation of map projections, a biaxial spheroid figure is adopted. The semimajor and semiminor axes are 3393.4 and 3375.7 km, respectively, with a polar flattening of 0.0052. For the computation of elevations, a topographic datum is defined by a gravity field described in terms of spherical harmonics of fourth order and fourth degree combined with a 6.1-mbar occulation pressure surface. This areoid can be approximated by a triaxial ellipsoid with semimajor axes of A = 3394.6 km and B = 3393.3 km and a semiminor axis of C = 3376.3 km. The semimajor axis A intersects the Martian surface at longitude 105??W. The dynamic flattening of Mars is 0.00525. The contour intercal of the maps is 1 km. For some prominent features where overlapping pictures from Mariner 9 are available, local contour maps at relatively larger scales were also compiled by photogrammetric methods on stereo plotters. ?? 1978.

  9. Oxygen foreshock of Mars

    Science.gov (United States)

    Yamauchi, M.; Lundin, R.; Frahm, R. A.; Sauvaud, J.-A.; Holmström, M.; Barabash, S.

    2015-12-01

    Mars Express (MEX) has operated for more than 10 years in the environment of Mars, providing solar wind ion observations from the Analyzer of Space Plasmas and Energetic Atoms experiment's Ion Mass Analyser (IMA). On 21 September 2008, MEX/IMA detected foreshock-like discrete distributions of oxygen ions at around 1 keV in the solar wind attached to the bow shock and this distribution was observed continuously up to more than 2000 km from the bow shock. Foreshock-like protons are also observed but at a shifted location from the oxygen by about 1000 km, at a slightly higher energy, and flowing in a slightly different direction than the oxygen ions. Both protons and oxygen ions are flowing anti-sunward at different angles with respect to the solar wind direction. This is the first time that a substantial amount of planetary oxygen is observed upstream of the bow shock. Although rare, this is not the only IMA observation of foreshock-like oxygen: oxygen ions are sometimes observed for a short period of time (<5 min) inside the foreshock region. These observations suggest a new escape channel for planetary ions through the acceleration in the bow shock-magnetosheath region.

  10. Water on early Mars

    Science.gov (United States)

    Carr, M.H.

    1996-01-01

    Large flood channels, valley networks and a variety of features attributed to the action of ground ice indicate that Mars emerged from heavy bombardment 3.8 Ga ago, with an inventory of water at the surface equivalent to at least a few hundred metres spread over the whole planet, as compared with 3 km for the Earth. The mantle of Mars is much drier than that of the Earth, possibly as a result of global melting at the end of accretion and the lack of plate tectonics to subsequently reintroduce water into the interior. The surface water resided primarily in a porous, kilometres-thick megaregolith created by the high impact rates. Under today's climatic conditions groundwater is trapped below a thick permafrost zone. At the end of heavy bombardment any permafrost zone would have been much thinner because of the high heat flows, but climatic conditions may have been very different then, as suggested by erosion rates 1000 times higher than subsequent rates. Water trapped below the permafrost periodically erupted onto the surface to form large flood channels and lakes. Given abundant water at the surface and sustained volcanism, hydrothermal activity must have frequently occurred but we have yet to make the appropriate observations to detect the results of such activity.

  11. [Cryptobiosphere of Mars].

    Science.gov (United States)

    Gal'chenko, V F

    2003-01-01

    The US Viking missions (1975-1976) failed to discover any biological activity on the surface of Mars. Yet, life may exist in the planet lithosphere which was found to contain a substantial amount of water. Martian interior can also provide microbial cryptolife with sources of carbon (CO, CO2, CH4) and energy (reduced elements and compounds, e.g. H2, CO, H2S, NH4+, CH4, Fe3+). Microorganisms identical to the Earth's anaerobic methanogens, sulfate reducers, acetogens, denitrifiers etc. are the most probable Martian aborigines. Well-balanced continuous functioning of the Martian cryptobiosphere implies closure of biochemical carbon, sulfur and nitrogen cycles which cannot be reached but with participation of organotrophic and anaerobic hydrolytic and zymotic organisms, ammonifiers and denitrifiers. Considering the low intensity of biological and chemical processes in the absence of surface hydrosphere, low-power atmosphere and cryptobiosphere closure on Mars, and slow global energy matter cycles, evolution of the presumable Martian cryptolife should also go at a slack pace and directions and forms of the evolution of living substance can have little in common with those on Earth. Comprehensive investigations of the Martian biota will employ a great variety of geochemical, radi- and stable isotope, microbiological, enzymatic and molecular biology methods.

  12. Water on early Mars.

    Science.gov (United States)

    Carr, M H

    1996-01-01

    Large flood channels, valley networks and a variety of features attributed to the action of ground ice indicate that Mars emerged from heavy bombardment 3.8 Ga ago, with an inventory of water at the surface equivalent to at least a few hundred metres spread over the whole planet, as compared with 3 km for the Earth. The mantle of Mars is much drier than that of the Earth, possibly as a result of global melting at the end of accretion and the lack of plate tectonics to subsequently reintroduce water into the interior. The surface water resided primarily in a porous, kilometres-thick megaregolith created by the high impact rates. Under today's climatic conditions groundwater is trapped below a thick permafrost zone. At the end of heavy bombardment any permafrost zone would have been much thinner because of the high heat flows, but climatic conditions may have been very different then, as suggested by erosion rates 1000 times higher than subsequent rates. Water trapped below the permafrost periodically erupted onto the surface to form large flood channels and lakes. Given abundant water at the surface and sustained volcanism, hydrothermal activity must have frequently occurred but we have yet to make the appropriate observations to detect the results of such activity.

  13. Mars Exploration Rover mission

    Science.gov (United States)

    Crisp, Joy A.; Adler, Mark; Matijevic, Jacob R.; Squyres, Steven W.; Arvidson, Raymond E.; Kass, David M.

    2003-10-01

    In January 2004 the Mars Exploration Rover mission will land two rovers at two different landing sites that show possible evidence for past liquid-water activity. The spacecraft design is based on the Mars Pathfinder configuration for cruise and entry, descent, and landing. Each of the identical rovers is equipped with a science payload of two remote-sensing instruments that will view the surrounding terrain from the top of a mast, a robotic arm that can place three instruments and a rock abrasion tool on selected rock and soil samples, and several onboard magnets and calibration targets. Engineering sensors and components useful for science investigations include stereo navigation cameras, stereo hazard cameras in front and rear, wheel motors, wheel motor current and voltage, the wheels themselves for digging, gyros, accelerometers, and reference solar cell readings. Mission operations will allow commanding of the rover each Martian day, or sol, on the basis of the previous sol's data. Over a 90-sol mission lifetime, the rovers are expected to drive hundreds of meters while carrying out field geology investigations, exploration, and atmospheric characterization. The data products will be delivered to the Planetary Data System as integrated batch archives.

  14. Safety during MARS exercise

    CERN Multimedia

    2015-01-01

    It is MARS(1) time again! All employed members of the CERN personnel are currently undergoing the annual MARS evaluations.   This is also a good occasion for supervisors and their supervisees to fill in or update the OHS-0-0-3 form(2) “Identification of occupational hazards”. Filling in the OHS-0-0-3 form is an opportunity to assess any safety issues related to the supervisee's activities.  Each of us should, together with our supervisor, regularly identify and assess the hazards we may be exposed to in the course of our professional activities and reflect on how to control and mitigate them. When filling in the OHS form for the first time, it is important to determine any potential hazards as well as the corresponding preventive measures, in particular training and protective equipment. When updating the form, please review the available information to ensure that it still corresponds to the current activities. The form should be updated w...

  15. Non-equilibrium radiation of water vapor and retrieval of H2O in the mesosphere and lower thermosphere.

    Science.gov (United States)

    Manuilova, Rada; Feofilov, Artem; Kutepov, Alexander; Yankovsky, Valentine

    2015-04-01

    In the study the modern investigations of vibrational kinetics of H2O molecule in the middle atmosphere and development of the models of non-equilibrium radiation of water vapor in the IR ro-vibrational bands are discussed. Our model accounts for 13 excited vibrational states up to energies 7445 1/cm. In this model, 54 vibrational-translational (V-T) and vibrational-vibrational (V-V) processes of energy exchange at collisions of H2O with N2, O2 and O, which are important at the atmospheric conditions, were taken into account. Different variants of possible values of the rate constants of non-elastic collisional processes were analyzed considering the experimental data. Our consideration of the source of excitation of the first vibrational level H2O(010) due to quasiresonance energy transfer between the first vibrational levels of O2 and H2O molecules is based on the YM-2011 model of electronic-vibrational kinetics of excited products of ozone and oxygen photolysis in the mesosphere and lower thermosphere (MLT). In the model we solved the system of 45 kinetic equations for populations of electronically-vibrationally excited levels of oxygen molecule and excited oxygen atom O(1D). Using the YM-2011 model of electronic-vibrational kinetics of excited products of ozone and oxygen photolysis in the MLT and the model of vibrational kinetics of H2O molecule which has been developed enables us to retrieve altitude profiles of H2O concentrations from the measurements of 6.3 mkm H2O radiance in SABER/TIMED experiment. Currently, the experimental data for the processes of (V-T) and (V-V) energy exchanges occurring at the collisions with atmospheric molecules and atoms are available only for the transitions involving the lowest vibrational levels. In our 14-level model (the upper levels are 002, 101, 200) and in the latest 25-level model, which utilizes 21 levels of the main isotope molecule up to 050, 031, 130, 210 and 012 at 9000 1/cm, and also in all former models, it was

  16. Some results on the upper atmosphere deduced from satellite occultation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Felske, D.; Knuth, R.; Martini, L.; Ohle, K.H.; Sonnemann, G.; Stark, B.

    1980-08-01

    Measurements of neutral gas densities in the upper atmosphere deduced from extinction profiles from the Intercosmos 1, 4, 7, 11 and 16 and SOLRAD 9 and 10 solar radiation satellites at sunrise and sunset are presented. Occultation measurements in the Lyman alpha range have revealed the presence of an anomalously high absorption above 110 km in winter, which may be explained by high densities of water in the thermosphere. Calculations of oxygen densities based on extinction profiles measured in Lyman alpha and the Schumann-Runge range also indicate the presence of high densities of NO, and an unknown Lyman alpha absorber of molecular weight corresponding to that of water. Observations obtained for the D-region winter anomaly indicate that the wavelike ionization variations have counterparts in similar neutral thermosphere density variations, which may influence the ion production and/or loss processes. Finally, short-term neutral density fluctuations between 90 and 300 km measured during a strong F-region disturbance are presented which demonstrate sharp rises in O density and decreases in O2 density accompanied by increases in electron concentration during the first phase of the disturbance, the opposite changes during the second phase, and complex mixing variations between O and O2 and their plasma counterparts in the recovery phase.

  17. Martian clouds observed by Mars Global Surveyor Mars Orbiter Camera

    OpenAIRE

    Wang, Huiqun; Ingersoll, Andrew P.

    2002-01-01

    We have made daily global maps that cover both polar and equatorial regions of Mars for Ls 135°–360° and 0°–111° using the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red and blue wide-angle swaths taken from May 1999 to January 2001. We study the seasonal distribution of condensate clouds and dust clouds during roughly 1 Martian year using these daily global maps. We present the development and decay of the tropical cloud belt and the polar hoods, the spatial and temporal distributi...

  18. Energy Input and Dissipation in the Ionosphere-Thermosphere (IT) System

    Science.gov (United States)

    Huang, C. Y.; Huang, Y.; Su, Y. J.; Sutton, E. K.; Hairston, M. R.

    2015-12-01

    AFRL The long-held view of energy input and dissipation into the IT system says that the primary region in which dynamic and electrodynamic processes occur is the auroral zone. Recent observations have indicated that this may not be completely true. The dominant form of energy input to the IT system is electromagnetic, and not particle precipitation. Poynting flux measured on DMSP spacecraft during storms indicates that energy can be deposited at all local times (LTs) in both hemispheres at polar latitudes as well as in the auroral zones. One major effect of this energy input is Joule heating of the ionosphere and thermosphere. We have analyzed the ion temperature measured by DMSP for a number of storms. During storm main phases, the increase in ion temperature maximizes at polar latitudes. We have processed neutral densities from CHAMP, GRACE and GOCE which show localized Joule heating at extremely high latitudes in both hemispheres. We conclude that energy input and dissipation occurs in the polar cap as well as in the auroral zones. Our results require a re-examination of the processes by which energy can enter the IT system, as well as where and how energy is transferred to ions and neutrals

  19. Thermosphere variation at different altitudes over the northern polar cap during magnetic storms

    Science.gov (United States)

    Huang, Yanshi; Wu, Qian; Huang, Cheryl Y.; Su, Yi-Jiun

    2016-08-01

    In this study, we report observations and simulation results of heated neutrals at various altitudes inside the polar cap during two magnetic storms in January 2005. The Poynting flux measurements from the Defense Meteorological Satellite Program (DMSP) satellites show enhanced energy input in the polar cap during the storm main phase, which is underestimated in the TIE-GCM simulation. Neutral temperature measurements at 250 km from the ground-based Fabry-Perot Interferometer (FPI) at Resolute Bay are presented, along with the neutral density observations at 360 km and 470 km from Challenging Minisatellite Payload (CHAMP) and the Gravity Recovery and Climate Experiment (GRACE) satellites, respectively. These data have been analyzed to demonstrate the altitudinal dependence of neutral response to the storm energy input. By comparing the TIE-GCM simulation results and the observations, we demonstrate that Poynting fluxes as well as the thermosphere response were underestimated in the model. The simulated neutral temperature at Resolute Bay increases by approximately 260° and 280° K for the two events, respectively, much lower than the observed temperature enhancements of 750° and 900° K. Neutral density enhancements with more than 30% increase over the background density were also observed at polar latitudes, with no clear distinction between the auroral zone and polar cap. All measurements indicate enhancements at high latitudes poleward of 80° magnetic latitude (MLAT) implying that substantial heating can occur within the polar cap during storms.

  20. Observations of planetary waves in the mesosphere-lower thermosphere during stratospheric warming events

    CERN Document Server

    Stray, N H; Espy, P J; Limpasuvan, V; Hibbins, R E

    2016-01-01

    This study investigates the effect of stratospheric sudden warmings (SSWs) on planetary wave (PW) activity in the mesosphere-lower thermosphere (MLT). PW activity near 95 km is derived from meteor wind data using a chain of eight SuperDARN radars at high northern latitudes that span longitudes from 150$^{\\circ}$ W to 25$^{\\circ}$ E and latitudes from 51 to 66$^{\\circ}$ N. Zonal wave number 1 and 2 components were extracted from the meridional wind for the years 2000-2008. The observed wintertime PW activity shows common features associated with the stratospheric wind reversals and the accompanying stratospheric warming events. Onset dates for seven SSW events accompanied by an elevated stratopause (ES) were identified during this time period using the Specified Dynamics Whole Atmosphere Community Climate Model (SD-WACCM). For the seven events, a significant enhancement in wave number 1 and 2 PW amplitudes near 95 km was found to occur after the wind reversed at 50 km, with amplitudes maximizing approximately ...

  1. Bayesian calibration of the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM

    Directory of Open Access Journals (Sweden)

    A. D. Richmond

    2009-05-01

    Full Text Available In this paper, we demonstrate a procedure for calibrating a complex computer simulation model having uncertain inputs and internal parameters, with application to the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM. We compare simulated magnetic perturbations with observations at two ground locations for various combinations of calibration parameters. These calibration parameters are: the amplitude of the semidiurnal tidal perturbation in the height of a constant-pressure surface at the TIE-GCM lower boundary, the local time at which this maximises and the minimum night-time electron density. A fully Bayesian approach, that describes correlations in time and in the calibration input space is implemented. A Markov Chain Monte Carlo (MCMC approach leads to potential optimal values for the amplitude and phase (within the limitations of the selected data and calibration parameters but not for the minimum night-time electron density. The procedure can be extended to include additional data types and calibration parameters.

  2. New non-LTE model of OH(v) in the mesopshere/lower thermosphere

    Science.gov (United States)

    Panka, Peter; Kutepov, Alexander; Kalogerakis, Konstantinos; Janches, Diego; Feofilov, Artem; Rezac, Ladi; Marsh, Daniel; Yigit, Erdal

    2017-04-01

    We present a new detailed non-LTE model of OH(v) for the nighttime mesosphere/lower thermosphere. The model accounts for chemical production of vibrationally excited OH and for various vibrational-vibrational (VV) and vibrational-translational (VT) energy exchanges with main atmospheric constituents. The new feature was added to account for the "indirect" vibrational-electronic (VE) mechanism OH(v)→O(1D)→N2(v) of the OH vibrational energy transfer to N2, recently suggested by Sharma et al. [2015] and confirmed through laboratory studies by Kalogerakis et al. [2016]. We study the impact of this mechanism on the OH(v) populations and emissions in the two SABER channels at 1.6 and 2.0 μm. We also discuss the implications this mechanism will have on the retrieval of OH and O densities, as well as its effects on the nighttime CO2 density retrievals from the SABER 4.3 μm channel.

  3. Study of atomic oxygen greenline dayglow emission in thermosphere during geomagnetic storm conditions

    Science.gov (United States)

    Bag, T.; Singh, Vir; Sunil Krishna, M. V.

    2017-01-01

    The influence of geomagnetic storms on the atomic oxygen greenline (557.7 nm) dayglow emission in thermosphere is studied during solar active and solar quiet conditions. This study is primarily based on the photochemical model with inputs obtained from experimental observations and empirical models. The updated rate coefficients, quantum yields and related cross-sections have been used from experimental results and theoretical studies. This study is presented for a low latitude station Tirunelveli (8.7°N, 77.8°E), India. The volume emission rate (VER) has been calculated using densities and temperatures from the empirical models. The modeled VER shows a positive correlation with the Dst index. The VER also shows a negative correlation with the number densities of O, O2, and N2. The VER, calculated at peak emission altitude, exhibits depletion during the main phase of the storm. The altitude of peak emission rate is unaffected by the geomagnetic storm activity. The study also reveals that the peak emission altitude depends on the F10.7 solar index. The peak emission altitude moves upward as the value of F10.7 solar index increases.

  4. THz limb sounder (TLS) for lower thermospheric wind, oxygen density, and temperature

    Science.gov (United States)

    Wu, Dong L.; Yee, Jeng-Hwa; Schlecht, Erich; Mehdi, Imran; Siles, Jose; Drouin, Brian J.

    2016-07-01

    Neutral winds are one of the most critical measurements in the lower thermosphere and E region ionosphere (LTEI) for understanding complex electrodynamic processes and ion-neutral interactions. We are developing a high-sensitivity, low-power, noncryogenic 2.06 THz Schottky receiver to measure wind profiles at 100-140 km. The new technique, THz limb sounder (TLS), aims to measure LTEI winds by resolving the wind-induced Doppler shift of 2.06 THz atomic oxygen (OI) emissions. As a transition between fine structure levels in the ground electronic state, the OI emission is in local thermodynamic equilibrium (LTE) at altitudes up to 350 km. This LTE property, together with day-and-night capability and small line-of-sight gradient, makes the OI limb sounding a very attractive technique for neutral wind observations. In addition to the wind measurement, TLS can also retrieve [OI] density and neutral temperature in the LTEI region. TLS leverages rapid advances in THz receiver technologies including subharmonically pumped (SHP) mixers and Schottky-diode-based power multipliers. Current SHP Schottky receivers have produced good sensitivity for THz frequencies at ambient environment temperatures (120-150 K), which are achievable through passively cooling in spaceflight. As an emerging technique, TLS can fill the critical data gaps in the LTEI neutral wind observations to enable detailed studies on the coupling and dynamo processes between charged and neutral molecules.

  5. Seasonal variations in the equatorial thermospheric wind measured at Arequipa, Peru

    Energy Technology Data Exchange (ETDEWEB)

    Biondi, M.A.; Merriwether, J.W.; Fejer, B.G.; Gonzalez, S.A.

    1990-08-01

    Studies have been carried out Arequipa, Peru, of the seasonal variations in the thermospheric winds at moderate solar flux levels and geomagnetic activity. Fabry-Perot interferometer measurements of the doppler shifts in the 630.0 nm nightglow emission line from March to August 1983 and from April to October 1988 have yielded monthly-average meridional winds that are nearly zero (<50 m/s) and possible fluctuating in direction through much of the night but develop a southward flow at 50 - 100 m/s in the early and the late night from May onward. The average zonal winds are eastward throughout the night, reaching peak velocities before local midnight and then decreasing. The peak velocities increase to a maximum around the June solstice. The winds are generally stronger in 1988 than in 1983, even thought the solar EUV fluxes are comparable fro both years. Comparison of the present results with earlier satellite measurements, as embodied in the Horizontal Wind Model of Hedin et al., reveals generally satisfactory agreement at the equinox and June solstice, except for the June 1988 period. NCAR Therospheric General Circulation Model, calculated for similar solar flux levels, yields meridional and zonal wind variations which exhibit the same temporal behaviors but generally smaller values than the present measurements.

  6. Overturning instability in the mesosphere and lower thermosphere: analysis of instability conditions in lidar data

    Directory of Open Access Journals (Sweden)

    L. Hurd

    2009-07-01

    Full Text Available Resonant sodium lidar measurements from the transition region between the mesosphere and lower thermosphere have revealed frequently-occurring overturning events characterized by vertical scales of ~3–6 km and timescales of several hours. Larsen et al. (2004 proposed that a convective roll instability, similar to that found in the planetary boundary layer, is the likely mechanism responsible for the events. This type of instability requires an inflection point in the background winds near the center of the vortex roll with a low static stability region capped by an inversion. The earlier paper argued that the conditions required to support the instability are common in the altitude range where the features are found. In this paper, we use data from the University of Illinois sodium lidar that was located at the Starfire Optical Range near Albuquerque, New Mexico, and from the Maui/MALT Lidar Facility in Hawaii and present several cases that are used to examine the behavior of the inflection point in detail as a function of time during the evolution of the overturning event. In addition, we examine the background static stability conditions using the temperature data from the lidar.

  7. In situ observations of waves in Venus’s polar lower thermosphere with Venus Express aerobraking

    Science.gov (United States)

    Müller-Wodarg, Ingo C. F.; Bruinsma, Sean; Marty, Jean-Charles; Svedhem, Håkan

    2016-08-01

    Waves are ubiquitous phenomena found in oceans and atmospheres alike. From the earliest formal studies of waves in the Earth’s atmosphere to more recent studies on other planets, waves have been shown to play a key role in shaping atmospheric bulk structure, dynamics and variability. Yet, waves are difficult to characterize as they ideally require in situ measurements of atmospheric properties that are difficult to obtain away from Earth. Thus, we have incomplete knowledge of atmospheric waves on planets other than our own, and we are thereby limited in our ability to understand and predict planetary atmospheres. Here we report the first ever in situ observations of atmospheric waves in Venus’s thermosphere (130-140 km) at high latitudes (71.5°-79.0°). These measurements were made by the Venus Express Atmospheric Drag Experiment (VExADE) during aerobraking from 24 June to 11 July 2014. As the spacecraft flew through Venus’s atmosphere, deceleration by atmospheric drag was sufficient to obtain from accelerometer readings a total of 18 vertical density profiles. We infer an average temperature of T = 114 +/- 23 K and find horizontal wave-like density perturbations and mean temperatures being modulated at a quasi-5-day period.

  8. THz Limb Sounder (TLS) for Lower Thermospheric Wind, Oxygen Density, and Temperature

    Science.gov (United States)

    Wu, Dong L.; Yee, Jeng-Hwa; Schlecht, Erich; Mehdi, Imran; Siles, Jose; Drouin, Brian J.

    2016-01-01

    Neutral winds are one of the most critical measurements in the lower thermosphere and E region ionosphere (LTEI) for understanding complex electrodynamic processes and ion-neutral interactions. We are developing a high-sensitivity, low-power, noncryogenic 2.06 THz Schottky receiver to measure wind profiles at 100-140 km. The new technique, THz limb sounder (TLS), aims to measure LTEI winds by resolving the wind-induced Doppler shift of 2.06 THz atomic oxygen (OI) emissions. As a transition between fine structure levels in the ground electronic state, the OI emission is in local thermodynamic equilibrium(LTE) at altitudes up to 350km. This LTE property, together with day-and-night capability and small line-of-sight gradient, makes the OI limb sounding a very attractive technique for neutral wind observations. In addition to the wind measurement, TLS can also retrieve [OI] density and neutral temperature in the LTEI region. TLS leverages rapid advances in THz receiver technologies including subharmonically pumped (SHP)mixers and Schottky-diode-based power multipliers. Current SHP Schottky receivers have produced good sensitivity for THz frequencies at ambient environment temperatures (120-150 K), which are achievable through passively cooling in spaceflight. As an emerging technique, TLS can fill the critical data gaps in the LTEI neutral wind observations to enable detailed studies on the coupling and dynamo processes between charged and neutral molecules.

  9. Upper mesospheric lunar tides over middle and high latitudes during sudden stratospheric warming events

    Science.gov (United States)

    Chau, J. L.; Hoffmann, P.; Pedatella, N. M.; Matthias, V.; Stober, G.

    2015-04-01

    In recent years there have been a series of reported ground- and satellite-based observations of lunar tide signatures in the equatorial and low latitude ionosphere/thermosphere around sudden stratospheric warming (SSW) events. This lower atmosphere/ionosphere coupling has been suggested to be via the E region dynamo. In this work we present the results of analyzing 6 years of hourly upper mesospheric winds from specular meteor radars over a midlatitude (54°N) station and a high latitude (69°N) station. Instead of correlating our results with typical definitions of SSWs, we use the definition of polar vortex weaking (PVW) used by Zhang and Forbes. This definition provides a better representation of the strength in middle atmospheric dynamics that should be responsible for the waves propagating to the E region. We have performed a wave decomposition on hourly wind data in 21 day segments, shifted by 1 day. In addition to the radar wind data, the analysis has been applied to simulations from Whole Atmosphere Community Climate Model Extended version and the thermosphere-ionosphere-mesosphere electrodynamics general circulation model. Our results indicate that the semidiurnal lunar tide (M2) enhances in northern hemispheric winter months, over both middle and high latitudes. The time and magnitude of M2 are highly correlated with the time and associated zonal wind of PVW. At middle/high latitudes, M2 in the upper mesosphere occurs after/before the PVW. At both latitudes, the maximum amplitude of M2 is directly proportional to the strength of PVW westward wind. We have found that M2 amplitudes could be comparable to semidiurnal solar tide amplitudes, particularly around PVW and equinoxes. Besides these general results, we have also found peculiarities in some events, particularly at high latitudes. These peculiarities point to the need of considering the longitudinal features of the polar stratosphere and the upper mesosphere and lower thermosphere regions. For

  10. Mars Before the Space Age

    CERN Document Server

    Jones, Barrie W

    2008-01-01

    Mars has surely been scrutinised since the dawn of humankind. In the 16th century Tycho Brahe made accurate observations of the position of Mars that enabled Johannes Kepler to obtain his first two laws of planetary motion. In the 17th century the first telescope observations were made, but very little surface detail could be discerned. Throughout the 18th and 19th centuries telescopes improved, revealing many dark areas on the red tinted surface. After the close opposition of 1877 Giovanni Schiaparelli announced about 40 canali on Mars. This led to the saga of the canals of Mars, laid to rest in 1971 when Mariner 9 made observations from Martian orbit showing that the canali/canals of Mars do not exist. Belief that there was life on Mars was widespread in the 19th century, including the view that the dark areas were some form of plant life. This view persisted until Mariner 4 flew past Mars in 1965 and discovered a far thinner atmosphere than previously thought, with impact craters dominating the images. It ...

  11. Mars: a small terrestrial planet

    Science.gov (United States)

    Mangold, N.; Baratoux, D.; Witasse, O.; Encrenaz, T.; Sotin, C.

    2016-11-01

    Mars is characterized by geological landforms familiar to terrestrial geologists. It has a tenuous atmosphere that evolved differently from that of Earth and Venus and a differentiated inner structure. Our knowledge of the structure and evolution of Mars has strongly improved thanks to a huge amount of data of various types (visible and infrared imagery, altimetry, radar, chemistry, etc) acquired by a dozen of missions over the last two decades. In situ data have provided ground truth for remote-sensing data and have opened a new era in the study of Mars geology. While large sections of Mars science have made progress and new topics have emerged, a major question in Mars exploration—the possibility of past or present life—is still unsolved. Without entering into the debate around the presence of life traces, our review develops various topics of Mars science to help the search of life on Mars, building on the most recent discoveries, going from the exosphere to the interior structure, from the magmatic evolution to the currently active processes, including the fate of volatiles and especially liquid water.

  12. Kepler's "War on Mars"

    Science.gov (United States)

    Dorsey, William; Orchiston, W.; Stephenson, F. R.

    2011-01-01

    This paper presents an interpretation of how Johannes Kepler changed the study of astronomy. We propose that in his metaphorical "War on Mars,” the Astronomia Nova, Kepler used a revolutionary rhetoric to bring about the usurpation of seventeenth-century astronomy. We discuss how Kepler approached the well-established conceptual framework within which the hypotheses of Ptolemy, Copernicus and Tycho Brahe functioned, and how he sought comprehensive physical principles that could determine the true cause and form of the known Universe. We examine Kepler's need to redefine reality and his use of rhetoric in shaping his astronomical argument for a new astronomy, and we show that his new `laws’ represent a fusion of physics and geometry based upon astronomical observations. We suggest that although Kepler may have believed in and defended some Copernican ideas, his innovative Astronomia Nova opened up a whole new vista for international astronomy.

  13. Mars - an escaping planet?

    CERN Document Server

    Dvorak, R

    2005-01-01

    The chaotic behaviour of the motion of the planets in our Solar System is well established. Numerical experiments with a modified Solar System consisting of a more massive Earth have shown, that for special values of an enlargement factor K around 5 the dynamical state of a truncated planetary system (excluding Mercury and the outer planets Uranus and Neptune) is highly chaotic. On the contrary for values of the mass of the Earth up to the mass of Saturn no irregular dynamical behaviour was observed. We extended our investigations to the complete planetary system and showed, that this chaotic window found before still exists. Tests in different 'Solar Systems' showed that only including Jupiter and Saturn with their actual masses together with a 'massive' Earth (between 4 and 6 times more massive) destabilize the orbit of Mars so that even escapes from the system are possible.

  14. Geologic map of Mars

    Science.gov (United States)

    Tanaka, Kenneth L.; Skinner, James A.; Dohm, James M.; Irwin, Rossman P.; Kolb, Eric J.; Fortezzo, Corey M.; Platz, Thomas; Michael, Gregory G.; Hare, Trent M.

    2014-01-01

    This global geologic map of Mars, which records the distribution of geologic units and landforms on the planet's surface through time, is based on unprecedented variety, quality, and quantity of remotely sensed data acquired since the Viking Orbiters. These data have provided morphologic, topographic, spectral, thermophysical, radar sounding, and other observations for integration, analysis, and interpretation in support of geologic mapping. In particular, the precise topographic mapping now available has enabled consistent morphologic portrayal of the surface for global mapping (whereas previously used visual-range image bases were less effective, because they combined morphologic and albedo information and, locally, atmospheric haze). Also, thermal infrared image bases used for this map tended to be less affected by atmospheric haze and thus are reliable for analysis of surface morphology and texture at even higher resolution than the topographic products.

  15. Illustration of Launching Samples Home from Mars

    Science.gov (United States)

    2005-01-01

    One crucial step in a Mars sample return mission would be to launch the collected sample away from the surface of Mars. This artist's concept depicts a Mars ascent vehicle for starting a sample of Mars rocks on their trip to Earth.

  16. Mars Express en route for the Red Planet

    Science.gov (United States)

    2003-06-01

    The probe, weighing in at 1 120 kg, was built on ESA’s behalf by a European team led by Astrium. It set out on its journey to Mars aboard a Soyuz-Fregat launcher, under Starsem operational management. The launcher lifted off from Baïkonur in Kazakhstan on 2 June at 23.45 local time (17:45 GMT). An interim orbit around the Earth was reached following a first firing of the Fregat upper stage. One hour and thirty-two minutes after lift off the probe was injected into its interplanetary orbit. "Europe is on its way to Mars to stake its claim in the most detailed and complete exploration ever done of the Red Planet. We can be very proud of this and of the speed with which have achieved this goal", said David Southwood, ESA's Director of Science witnessing the launch from Baikonur. Contact with Mars Express has been established by ESOC, ESA’s satellite control centre, located in Darmstadt, Germany. The probe is pointing correctly towards the Sun and has deployed its solar panels. All on-board systems are operating faultlessly. Two days from now, the probe will perform a corrective manœuvre that will place it in a Mars-bound trajectory, while the Fregat stage, trailing behind, will vanish into space - there will be no risk of it crashing into and contaminating the Red Planet. Mars Express will then travel away from Earth at a speed exceeding 30 km/s (3 km/s in relation to the Earth), on a six-month and 400 million kilometre journey through the solar system. Once all payload operations have been checked out, the probe will be largely deactivated. During this period, the spacecraft will contact Earth only once a day. Mid-journey correction of its trajectory is scheduled for September. There in time for Christmas Following reactivation of its systems at the end of November, Mars Express will get ready to release Beagle 2. The 60 kg capsule containing the tiny lander does not incorporate its own propulsion and steering system and will be released into a collision

  17. NASA Mars Science Laboratory Rover

    Science.gov (United States)

    Olson, Tim

    2017-01-01

    Since August 2012, the NASA Mars Science Laboratory (MSL) rover Curiosity has been operating on the Martian surface. The primary goal of the MSL mission is to assess whether Mars ever had an environment suitable for life. MSL Science Team member Dr. Tim Olson will provide an overview of the rover's capabilities and the major findings from the mission so far. He will also share some of his experiences of what it is like to operate Curiosity's science cameras and explore Mars as part of a large team of scientists and engineers.

  18. Approach to Mars Field Geology

    Science.gov (United States)

    Muehlberger, William; Rice, James W.; Parker, Timothy; Lipps, Jere H.; Hoffman, Paul; Burchfiel, Clark; Brasier, Martin

    1998-01-01

    The goals of field study on Mars are nothing less than to understand the processes and history of the planet at whatever level of detail is necessary. A manned mission gives us an unprecedented opportunity to use the immense power of the human mind to comprehend Mars in extraordinary detail. To take advantage of this opportunity, it is important to examine how we should approach the field study of Mars. In this effort, we are guided by over 200 years of field exploration experience on Earth as well as six manned missions exploring the Moon.

  19. Mars Science Laboratory Entry Guidance Improvements for Mars 2018 (DRAFT)

    Science.gov (United States)

    Garcia-Llama, Eduardo; Winski, Richard G.; Shidner, Jeremy D.; Ivanov, Mark C.; Grover, Myron R.; Prakash, Ravi

    2011-01-01

    In 2011, the Mars Science Laboratory (MSL) will be launched in a mission to deliver the largest and most capable rover to date to the surface of Mars. A follow on MSL-derived mission, referred to as Mars 2018, is planned for 2018. Mars 2018 goals include performance enhancements of the Entry, Descent and Landing over that of its predecessor MSL mission of 2011. This paper will discuss the main elements of the modified 2018 EDL preliminary design that will increase performance on the entry phase of the mission. In particular, these elements will increase the parachute deploy altitude to allow for more time margin during the subsequent descent and landing phases and reduce the delivery ellipse size at parachute deploy through modifications in the entry reference trajectory design, guidance trigger logic design, and the effect of additional navigation hardware.

  20. Transconjunctival upper blepharoplasty.

    Science.gov (United States)

    Januszkiewicz, J S; Nahai, F

    1999-03-01

    Transconjunctival lower lid blepharoplasty now has an established role as an option in rejuvenation of the lower eyelid. Transconjunctival upper lid blepharoplasty, or transconjunctival removal of medial upper eyelid fat, also has a role in rejuvenation of the upper eyelid. However, this is a rather limited role. We have found this approach safe and efficacious as a primary as well as a secondary procedure for removal of excess medial upper eyelid fat. We report on 20 patients who have undergone this operation: 5 as a primary procedure and 15 as secondary. There were no complications, no revisions, and the patients have been uniformly happy with their results.

  1. Solar Energetic Particle Precipitation Effects on the ionosphere of Mars

    Science.gov (United States)

    Lillis, Robert; Larson, Davin; Luhmann, Janet; Lee, Christina; Jakosky, Bruce

    2016-10-01

    Solar Energetic Particles (SEPs) are an important, if irregular, source of ionization and energy input to the Martian atmosphere. As is the case for much-studied Polar Cap precipitation events on the earth, when SEPs precipitate into the Mars atmosphere, they cause heating, ionization, excitation and dissociation, leading to altitude-dependent changes in chemistry. We present a study of the effects of SEP ionization in the Martian atmosphere using data from the Mars Atmosphere and Volatile Evolution (MAVEN) mission. Specifically, we will correlate altitude profiles of thermal planetary ions (O+, CO2+ and O2+) and electrons measured by the Neutral Gas and Ion Mass Spectrometer (NGIMS) and Langmuir Probe on the MAVEN spacecraft with fluxes of energetic protons and electrons measured by the Solar Energetic Particle (SEP) detector. First, we will present case studies of this correlation, before and during SEP events to examine short-term effects of SEP ionization. We will also examine SEP ionization under different heliospheric conditions, leading to different SEP shadowing geometries and ionization rates. Second, we will present a statistical study showing the degree to which ionospheric densities are affected by the presence of energetic particles, as a function of altitude, SEP spectrum flux and solar zenith angle. This work will provide a better understanding of this important source of ionization in the Martian upper atmosphere and hence, how more frequent and more intense SEP events in Mars' past may have affected the structure of the Martian upper atmosphere and hence atmospheric escape.

  2. Magnetic activity at Mars - Mars Surface Magnetic Observatory

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Menvielle, M.; Merayo, José M.G.

    2012-01-01

    We use the extensive database of magnetic observations from the Mars Global Surveyor to investigate magnetic disturbances in the Martian space environment statistically, both close to and far from crustal anomalies. We discuss the results in terms of possible ionospheric and magnetospheric currents...... a magnetic experiment at the martian surface, the Mars Surface Magnetic Observatory (MSMO) including the science objectives, science experiment requirements, instrument and basic operations. We find the experiment to be feasible within the constraints of proposed stationary landing platforms....

  3. Boots on Mars: Earth Independent Human Exploration of Mars

    Science.gov (United States)

    Burnett, Josephine; Gill, Tracy R.; Ellis, Kim Gina

    2017-01-01

    This package is for the conduct of a workshop during the International Space University Space Studies Program in the summer of 2017 being held in Cork, Ireland. It gives publicly available information on NASA and international plans to move beyond low Earth orbit to Mars and discusses challenges and capabilities. This information will provide the participants a basic level of insight to develop a response on their perceived obstacles to a future vision of humans on Mars.

  4. The ballistic Mars hopper: An alternative Mars mobility concept

    OpenAIRE

    1987-01-01

    The ballistic Mars hopper is proposed as an alternative mobility concept for unmanned exploration of the martian surface. In the ballistic Mars hopper concept, oxygen and carbon monoxide produced from the martian atmosphere are used as propellants in a rocket propulsion system for an unmanned vehicle on suborbital trajectories between landing sights separated by distances of up to 1000 km. This mobility concept is seen as uniquely capable of allowing both intensive and extensive exploration o...

  5. The Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution Mission

    Science.gov (United States)

    Mahaffy, Paul R.; Benna, Mehdi; King, Todd; Harpold, Daniel N.; Arvey, Robert; Barciniak, Michael; Bendt, Mirl; Carrigan, Daniel; Errigo, Therese; Holmes, Vincent; Kellogg, James; Jaeger, Ferzan; Raaen, Eric; Tan, Florence

    2014-01-01

    The Neutral Gas and Ion Mass Spectrometer (NGIMS) of the Mars Atmosphere and Volatile Evolution Mission (MAVEN) is designed to measure the composition, structure, and variability of the upper atmosphere of Mars. The NGIMS complements two other instrument packages on the MAVEN spacecraft designed to characterize the neutral upper atmosphere and ionosphere of Mars and the solar wind input to this region of the atmosphere. The combined measurement set is designed to quantify atmosphere escape rates and provide input to models of the evolution of the martian atmosphere. The NGIMS is designed to measure both surface reactive and inert neutral species and ambient ions along the spacecraft track over the 125-500 km altitude region utilizing a dual ion source and a quadrupole analyzer.

  6. HST Observations of Comet-Induced Aurora on Mars during the Siding Spring Encounter

    Science.gov (United States)

    Clarke, John

    2014-10-01

    The martian upper atmosphere is likely to be strongly perturbed by the near collision with Comet C/2013 A1 (Siding Spring) on 19 Oct. 2014. This is a unique event in the history of space science, it will be the first time that we have a chance to study the close encounter of an active comet with a terrestrial planet. Significant mass and energy will be deposited in the upper atmosphere of Mars if the comet coma is sufficiently dense. Present estimates have Comet Siding Spring at a moderate production rate when it passes by Mars, which is expected to result in the strong perturbations of the martian atmosphere. This proposal is to make HST observations of the atmosphere of Mars before and during the comet encounter to measure the energy input to the upper atmosphere through the auroral emissions that will be produced by the deposition of energy of incoming water-group molecules. The observation of auroral emissions will permit a direct estimate of the total energy input to the martian upper atmosphere, and it will provide us a unique chance to determine the response of the martian atmosphere to strong auroral processes. This will likely be the only opportunity to make this measurement in the lifetime of HST, and it will provide support for the NASA MAVEN mission, which will have recently arrived in orbit about Mars.

  7. The distribution of particulate material on Mars

    Science.gov (United States)

    Christensen, Philip R.

    1991-01-01

    The surface materials on Mars were extensively studied using a variety of spacecraft and Earth-based remote sensing observations. These measurements include: (1) diurnal thermal measurements, used to determine average particle size, rock abundance, and the presence of crusts; (2) radar observations, used to estimate the surface slope distributions, wavelength scale roughness, and density; (3) radio emission observations, used to estimate subsurface density; (4) broadband albedo measurements, used to study the time variation of surface brightness and dust deposition and removal; and (5) color observations, used to infer composition, mixing, and the presence of crusts. Remote sensing observations generally require some degree of modeling to interpret, making them more difficult to interpret than direct observations from the surface. They do, however, provide a means for examining the surface properties over the entire planet and a means of sampling varying depths within the regolith. Albedo and color observations only indicate the properties of the upper-most few microns, but are very sensitive to thin, sometimes emphemeral dust coatings. Thermal observations sample the upper skin depth, generally 2 to 10 cm. Rock abundance measurements give an indirect indication of surface mantling, where the absence of rocks suggests mantles of several meters. Finally, radar and radio emission data can penetrate several meters into the surface, providing an estimate of subsurface density and roughness.

  8. Hydraulic Inferences for Mars From Geologic Mapping in Margaritifer Terra, Mars and Measurements of Terrestrial Analogs.

    Science.gov (United States)

    Fortezzo, C. M.; Williams, K. K.; Springer, A. E.

    2006-12-01

    Past hydrogeologic models of Mars have focused primarily on exploring a link between large scale groundwater systems and the Martian outflow channels. These groundwater models have generally given only slight consideration to the occurrence of smaller-scale valley network that dissect much of the southern highlands. Ongoing geologic and geomorphic mapping in 6 Mars Transverse Mercator 1:500K quadrangles (17.5ºS - 27.5ºS and 345ºE - 360ºE) in southeast Margaritifer Terra, Mars, shows valley networks are often associated with the internal and external slopes of the impact basin but are absent on the basin floor. We propose a sequence of ponding in the basin followed by infiltration into the subsurface, transmission down the regional slope and sapping valleys forming on the crater flanks. The Martian valley morphologies are analogous with morphologies of terrestrial spring-fed sapping processes (i.e., amphitheater-shaped heads, stubby tributaries, steep walls, and U-shaped valleys that maintain consistent width-depth ratios along their length). Flow measurements from spring-fed channels in the Navajo Sandstone near Escalante, Utah supply data from areas actively forming sapping valleys and provide insight into the interaction between surface-water and groundwater. Measurements taken during pre-monsoon and post-snow melt run-off and planned post- monsoonal measurements will provide a range of discharge values furnishing data to model the interaction of subsurface- and surface-water flow on Mars. Published stratigraphic models of Mars postulate that the upper kilometer of material is ejecta related well-mixed unsorted debris ranging from meter sized blocks down to dust sized particles overlying fractured bedrock. Detailed mapping using high resolution datasets allows for accurate characterization of surficial material properties on a local scale which will help to better understand influences on hydrologic variables (i.e. permeability, hydraulic conductivity, etc

  9. 2031, an edaphological Mars odyssey

    Science.gov (United States)

    Barrón, Vidal

    2016-04-01

    NASA is projecting to send humans to Mars in the 2030s. In the PICO session we will make a 4D experience, a journey in space and time. Wéll connect with a meeting in the future mission "Edaphos one" travelling to Mars in 2031. In that meeting, an international scientific team with one geophysicist, one mineralogist and two agronomist will review the state of the art of the geo-edaphological knowledge of the martian surface, based on the main Mars missions using orbiters (Mariner), landers (Viking) and rovers (Pathfinder, Spirit-Opportunity, Curiosity). A special attention will be devoted to the mineralogy of the iron oxides, as important aquamarkers. Finally, they discuss about the biological, physical and chemical limitations for plants growth on Mars. You can see the trailer of the presentation in this link: https://www.youtube.com/watch?v=yRS0tPNpvFU

  10. BUILDING ON THE MARS PLANET

    National Research Council Canada - National Science Library

    Valeriy Pershakov; Tatyana Petrova

    2012-01-01

    The main task is the terraforming of the Mars planet. Nowadays it is a very important task, because there are a lot of problems on the planet Earth, which deals with the exhaustion of natural resources...

  11. Mars Regolith Water Extractor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Mars Regolith Water Extractor (MRWE) is a system for acquiring water from the Martian soil. In the MRWE, a stream of CO2 is heated by solar energy or waste heat...

  12. Mars Solar Balloon Lander Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Mars Solar Balloon Lander (MSBL) is a novel concept which utilizes the capability of solar-heated hot air balloons to perform soft landings of scientific...

  13. Mars Exploration Science in 2050

    Science.gov (United States)

    Ehlmann, B. L.; Johnson, S. S.; Horgan, B.; Niles, P. B.; Amador, E. S.; Archer, P. D.; Byrne, S.; Edwards, C. S.; Fraeman, A. A.; Glavin, D. P.; Glotch, T. D.; Hardgrove, C.; Hayne, P. O.; Kite, E. S.; Lanza, N. L.; Lapotre, M. G. A.; Michalski, J.; Rice, M.; Rogers, A. D.

    2017-02-01

    We describe an approach to Mars exploration in 2050 and the decades leading in that couples fundamental science on the workings of planets and the search for life with collection of information on resources and hazards essential for human exploration.

  14. MARVY: Mars Velocity Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The successful landing of the large Mars rover Curiosity on August 5, 2012 outlined the increasing complexity of safely landing large rovers on the planet. A precise...

  15. Outstanding problems in Mars aeronomy

    Science.gov (United States)

    Luhmann, J. G.

    1995-01-01

    Although the Phobos-2 spacecraft recently obtained important results relevant to some of the major remaining questions in Mars aeronomy, much remains to be done. In particular, not since the Viking Landers have we made in-situ measurements of aeronomical quantities such as atmospheric and ionospheric densities and temperatures below 400 km altitude. We have never made magnetic field measurements at these altitudes. Without such measurements we cannot unambiguously resolve arguments concerning issues such as the significance of the planetary magnetic field in the solar wind interaction, or understand the atmospheric cycle that leads to escape to space. With the trio of future orbiters including Mars Observer, Mars-94, and Planet-B we should see a veritable explosion of new knowledge, but some gaps in aeronomical science coverage will still remain. This paper briefly reviews some of the major unsolved problems in Mars aeronomy, and points out which are expected to remain outstanding after this flotilla of missions.

  16. Ice at Mars lander site

    National Research Council Canada - National Science Library

    Showstack, Randy

    2008-01-01

    Eight dice‐sized bits of ice vanished within 4 days from a trench dug on Mars by the robotic arm on NASA's Phoenix lander, confirming what scientists suspected the material was. “It must be ice...

  17. Mars Aqueous Processing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mars Aqueous Processing System (MAPS) is an innovative method to produce useful building materials from Martian regolith. Acids and bases produced from the regolith...

  18. Interactive 3D Mars Visualization

    Science.gov (United States)

    Powell, Mark W.

    2012-01-01

    The Interactive 3D Mars Visualization system provides high-performance, immersive visualization of satellite and surface vehicle imagery of Mars. The software can be used in mission operations to provide the most accurate position information for the Mars rovers to date. When integrated into the mission data pipeline, this system allows mission planners to view the location of the rover on Mars to 0.01-meter accuracy with respect to satellite imagery, with dynamic updates to incorporate the latest position information. Given this information so early in the planning process, rover drivers are able to plan more accurate drive activities for the rover than ever before, increasing the execution of science activities significantly. Scientifically, this 3D mapping information puts all of the science analyses to date into geologic context on a daily basis instead of weeks or months, as was the norm prior to this contribution. This allows the science planners to judge the efficacy of their previously executed science observations much more efficiently, and achieve greater science return as a result. The Interactive 3D Mars surface view is a Mars terrain browsing software interface that encompasses the entire region of exploration for a Mars surface exploration mission. The view is interactive, allowing the user to pan in any direction by clicking and dragging, or to zoom in or out by scrolling the mouse or touchpad. This set currently includes tools for selecting a point of interest, and a ruler tool for displaying the distance between and positions of two points of interest. The mapping information can be harvested and shared through ubiquitous online mapping tools like Google Mars, NASA WorldWind, and Worldwide Telescope.

  19. Mars Express releases Beagle 2

    Science.gov (United States)

    2003-12-01

    At 9:31 CET, the crucial sequence started to separate the Beagle 2 lander from Mars Express. As data from Mars Express confirm, the pyrotechnic device was fired to slowly release a loaded spring, which gently pushed Beagle 2 away from the mother spacecraft. An image from the onboard visual monitoring camera (VMC) showing the lander drifting away is expected to be available later today. Since the Beagle 2 lander has no propulsion system of its own, it had to be put on the correct course for its descent before it was released. For this reason, on 16 December the trajectory of the whole Mars Express spacecraft had to be adjusted to ensure that Beagle 2 would be on course to enter the atmosphere of Mars. This manoeuvre, called "retargeting'' was critical: if the entry angle is too steep, the lander could overheat and burn up in the atmosphere; if the angle is too shallow, the lander might skim like a pebble on the surface of a lake and miss its target. This fine targeting and today's release were crucial manoeuvres for which ESA's Ground Control Team at ESOC (European Space Operations Centre) had trained over the past several months. The next major milestone for Mars Express will be the manoeuvre to enter into orbit around Mars. This will happen at 3:52 CET on Christmas morning, when Beagle 2 is expected to land on the surface of Mars. "Good teamwork by everybody - ESA, industry and the Beagle 2 team - has got one more critical step accomplished. Mars, here comes Europe!" said David Southwood, ESA Director of Science.

  20. Joule Heating, Particle Precipitation and Dynamical Heating as Possible Tidal Sources in the Antarctic Winter Lower Thermosphere

    Science.gov (United States)

    Fong, W.; Chu, X.; Lu, X.; Chen, C.; Yu, Z.; Fuller-Rowell, T. J.; Richmond, A. D.; Codrescu, M.

    2014-12-01

    Winter temperature tides observed by lidar at McMurdo (77.8°S, 166.7°E), Antarctica, show less than 3 K diurnal and semidiurnal tidal amplitude below 100 km. However, above 100 km, the diurnal and semidiurnal tidal amplitudes grow super-exponentially and can reach at least 15 K near 110 km, which are exceeding that of the freely propagating tides originating from the lower atmosphere. Such fast growth exists for all Kp index cases and diurnal amplitude increases to 15-30 K at 110 km with larger Kp indices corresponding to larger tidal amplitudes and faster growth rates. Combining with the slopes of diurnal tidal phases being steeper above 100 km, and the tidal phases barely changing with altitude from 100 to 106 km, it indicates that in-situ tidal sources may exist near or above 100 km. In this paper, we utilize the coupled thermosphere ionosphere plasmasphere electrodynamics (CTIPe) model to investigate possible sources/mechanisms that lead to the fast amplitude growth of tides in the polar winter region. Joule heating, particle precipitation, and dynamical heating are likely to be the dominant thermospheric tidal sources, according to CTIPe model. Interestingly, the CTIPe tidal amplitudes induced by these sources form a concentric pattern with its center located at the geomagnetic pole, implying that the geomagnetic activity may play an important role. Furthermore, dynamical heating, which includes adiabatic heating/cooling and vertical advection, is likely to be the explanation of the fast growth of diurnal tidal amplitudes even under quiet condition of geomagnetic activity as observed by lidar. We also found that the tides propagating from the lower atmosphere is a minor factor for the fast increase of thermospheric diurnal tides in Antarctica.

  1. Retrieval algorithm for densities of mesospheric and lower thermospheric metal and ion species from satellite borne limb emission signals

    Science.gov (United States)

    Langowski, M.; Sinnhuber, M.; Aikin, A. C.; von Savigny, C.; Burrows, J. P.

    2013-05-01

    Meteoroids bombard the earth's atmosphere during its orbit around the sun, depositing a highly varying and significant amount of matter into the thermosphere and mesosphere. The strength of the material source needs to be characterized and its impact on atmospheric chemistry assessed. In this study an algorithm for the retrieval of metal and metal ion number densities for a two-dimensional (latitude, altitude) grid is described and explained. Dayglow emission spectra of the mesosphere and lower thermosphere are used, which are obtained by passive satellite remote sensing with the SCIAMACHY instrument on Envisat. The limb scans cover the tangent altitude range from 50 to 150 km. Metals and metal ions are strong emitters in this region and form sharply peaked layers with a FWHM of several 10 km in the mesosphere and lower thermosphere with peak altitudes between 90 to 110 km. The emission signal is first separated from the background signal, arising from Rayleigh and Raman scattering of solar radiation by air molecules. A forward radiative transfer model calculating the slant column density (SCD) from a given vertical distribution was developed. This non-linear model is inverted in an iterative procedure to yield the vertical profiles for the emitting species. Several constraints are applied to the solution, for numerical stability reasons and to get physically reasonable solutions. The algorithm is applied to SCIAMACHY limb-emission observations for the retrieval of Mg and Mg+ using emission signatures at 285.2 and 279.6/280.4 nm, respectively. Results are presented for these three lines as well as error estimations and sensitivity tests on different constraint strength and different separation approaches for the background signal.

  2. Europe's eye on Mars: first spectacular results from Mars Express

    Science.gov (United States)

    2004-01-01

    Although the seven scientific instruments on board Mars Express are still undergoing a thorough calibration phase, they have already started collecting amazing results. The first high-resolution images and spectra of Mars have already been acquired. This first spectacular stereoscopic colour picture was taken on 14 January 2004 by ESA’s Mars Express satellite from 275 km above the surface of Mars by the High Resolution Stereo Camera (HRSC). This image is available on the ESA portal at: http://mars.esa.int The picture shows a portion of a 1700 km long and 65 km wide swath which was taken in south-north direction across the Grand Canyon of Mars (Valles Marineris). It is the first image of this size that shows the surface of Mars in high resolution (12 metres per pixel), in colour, and in 3D. The total area of the image on the Martian surface (top left corner) corresponds to 120 000 km². The lower part of the picture shows the same region in perspective view as if seen from a low-flying aircraft. This perspective view was generated on a computer from the original image data. One looks at a landscape which has been predominantly shaped by the erosional action of water. Millions of cubic kilometres of rock have been removed, and the surface features seen now such as mountain ranges, valleys, and mesas, have been formed. The HRSC is just one of the instruments to have collected exciting data. To learn more about the very promising beginning to ESA's scientific exploration of Mars, media representatives are invited to attend a press conference on Friday, 23 January 2004, at 11:00 CET at ESA’s Space Operations Centre in Darmstadt, Germany, and in video-conference with the other ESA centres. There, under the auspices of ESA Council Chair at Ministerial level, Germany's Minister for Education and Research, Mrs Edelgard Bulmahn, ESA's Director of the Scientific Programme, Prof. David Southwood and the Principal Investigators of all instruments on board Mars Express will

  3. Interplanetary dust particles, not wind blown dust, control high altitude ice clouds on Mars

    Science.gov (United States)

    Hartwick, Victoria; Toon, Owen B.

    2016-10-01

    Water ice clouds on Mars are commonly observed at high altitudes. However, current generation Mars three-dimensional general circulation models (GCM) struggle to reproduce clouds above approximately 20-30 km. On Mars, as on Earth, ice cloud formation likely initiates by heterogeneous nucleation, which requires a population of suspended ice nuclei contiguous with supersaturated atmospheric water vapor. Although supersaturation is observed at high altitudes and has been reproduced in models, models predict very few ice nuclei. The small number of ice nuclei in the upper atmosphere is due to the assumption in Mars GCMs that the only source of ice nuclei is dust from the Martian surface. However, terrestrial mesospheric noctilucent clouds have been shown to form by ice nucleation on particles originating from ablated micrometeroids. Therefore, it is reasonable to assume that a population of micrometeoric ablation biproducts on Mars exists and can act as a site for cloud nucleation at high altitudes. We present simulations using the Community Atmosphere Model for Mars (MarsCAM) based on the National Center for Atmospheric Research (NCAR) Community Atmosphere Model for Earth,coupled with a physically based, state-of-the-art cloud and dust physics model, the Community Aerosol and Radiation Model for Atmospheres (CARMA) to show that ablating micrometeoroids can yield abundant ice nuclei throughout the upper atmosphere of Mars. We find that simulations including a constant annual micrometeoroid flux allows us to reproduce the observed properties of high altitude water ice clouds including vertical distribution and particle size. In general, effective radius decreases with increasing altitude. We have additionally explored the impact of variable ablation rates. Preliminary results suggest that relatively high ablation rates, near or greater than 50%, are required to reproduce observed cloud features.

  4. Nonvariceal upper gastrointestinal bleeding

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Stephen J.; Weldon, Derik; Sun, Shiliang [University of Iowa, Department of Radiology, Iowa, IA (United States); Golzarian, Jafar [University of Iowa, Department of Radiology, Iowa, IA (United States); University of Iowa, Department of Radiology, Carver College of Medicine, Iowa, IA (United States)

    2007-07-15

    Nonvariceal upper gastrointestinal bleeding (NUGB) remains a major medical problem even after advances in medical therapy with gastric acid suppression and cyclooxygenase (COX-2) inhibitors. Although the incidence of upper gastrointestinal bleeding presenting to the emergency room has slightly decreased, similar decreases in overall mortality and rebleeding rate have not been experienced over the last few decades. Many causes of upper gastrointestinal bleeding have been identified and will be reviewed. Endoscopic, radiographic and angiographic modalities continue to form the basis of the diagnosis of upper gastrointestinal bleeding with new research in the field of CT angiography to diagnose gastrointestinal bleeding. Endoscopic and angiographic treatment modalities will be highlighted, emphasizing a multi-modality treatment plan for upper gastrointestinal bleeding. (orig.)

  5. A theoretical comparison of internal gravity wave propagation and dissipation in high and low temperature thermospheres Implications for orbiting spacecraft

    Science.gov (United States)

    Hickey, M. P.

    1987-01-01

    In this paper the propagation and dissipation characteristics of a number of individual internal gravity waves are discussed and compared by using a multilayer, time-averaged model in which the waves lose energy due to viscous, thermal conduction and ion-drag dissipation. From this both the height and horizontal distance (from an assumed 'source') at which the waves achieve a maximum density amplitude may be determined. Such calculations are performed for both a very hot and a very cold thermosphere, and the subsequent differences in the wave characteristics and their relation to the control of orbiting spacecraft for each of these is discussed.

  6. Moon and Mars Analog Mission Activities for Mauna Kea 2012

    Science.gov (United States)

    Graham, Lee D.; Morris, Richard V.; Graff, Trevor G.; Yingst, R. Aileen; tenKate, I. L.; Glavin, Daniel P.; Hedlund, Magnus; Malespin, Charles A.; Mumm, Erik

    2012-01-01

    Rover-based 2012 Moon and Mars Analog Mission Activities (MMAMA) scientific investigations were recently completed at Mauna Kea, Hawaii. Scientific investigations, scientific input, and science operations constraints were tested in the context of an existing project and protocols for the field activities designed to help NASA achieve the Vision for Space Exploration. Initial science operations were planned based on a model similar to the operations control of the Mars Exploration Rovers (MER). However, evolution of the operations process occurred as the analog mission progressed. We report here on the preliminary sensor data results, an applicable methodology for developing an optimum science input based on productive engineering and science trades discussions and the science operations approach for an investigation into the valley on the upper slopes of Mauna Kea identified as "Apollo Valley".

  7. Oxygen dayglow emissions as proxies for atomic oxygen and ozone in the mesosphere and lower thermosphere

    Science.gov (United States)

    Yankovsky, Valentine A.; Martyshenko, Kseniia V.; Manuilova, Rada O.; Feofilov, Artem G.

    2016-09-01

    The main goal of this study is to propose and then to justify a set of methods for retrieving the [O] and [O3] altitude distributions from the observation of emissions of the excited oxygen molecules and O(1D) atom at daytime in the mesosphere and lower thermosphere (MLT) region. In other words, we propose retrieving the [O] and [O3] using the proxies. One of the main requirements for the proxy is that the measured value should be directly related to a variable of our interest while, at the same time, the influence of the proxies on [O3] and [O(3P)] should be minimal. For a comprehensive analysis of different O3 and O(3P) proxies, we use a full model of electronic vibrational kinetics of excited products of O3 and O2 photolysis in the MLT of the Earth. Based on this model, we have tested five excited components; namely, O2(b1Σg+, v = 0, 1, 2), O2(a1Δg , v = 0) and O(1D) as the [O3] and [O(3P)] proxies in the MLT region. Using an analytical approach to sensitivity studies and uncertainty analysis, we have therefore developed the following methods of [O(3P)] and [O3] retrieval, which utilise electronic-vibrational transitions from the oxygen molecule second singlet level (O2(b1 Σg+, v = 0, 1, 2). We conclude that O2(b1 Σg+, v = 2) and O2(b1 Σg+, v = 0) are preferable proxies for [O(3P)] retrieval in the altitude range of 90-140 km, while O2(b1 Σg+, v = 1) is the best proxy for [O3] retrieval in the altitude range of 50-98 km.

  8. New SMILES retrievals of ozone in the mesosphere and lower thermosphere region

    Science.gov (United States)

    Kuribayashi, Kouta; Kasai, Yasuko; Orsolini, Yvan; Limpasuvan, Varavut

    2016-07-01

    Ozone in mesosphere and lower thermosphere (MLT) region has been observed from space since three decades. We examine ozone in MLT region using observations from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the Japanese Experiment Module (JEM) of the International Space Station (ISS) between 12 October 2009 and 21 April 2010. We develop a new retrieval to improve upon previous ozone products, especially in the ozone secondary layer. One of the improvements in our new SMILES NICT level 2 product version 3.1.0 is that the profiles of the background atmosphere (altitude, pressure, and temperature) were calculated based on the global model GAIA (Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy) to ensure the internal consistency of these profiles. We assess the quality of the new SMILES NICT Level2 product version 3.1.0 in the MLT region, by comparing with various satellite observations (such as SABER, GOMOS) and model calculations performed using the same background atmosphere as calculated from GAIA at the each observation point. This is to avoid that differences of ozone amount in the same air mass being caused by the use of different atmospheric conditions for calculation of volume mixing ratio from ozone density. We examine the differences caused by the vertical resolution, as well as random errors and systematic errors. The new SMILES ozone product shows good agreement with observations from other satellites in the MLT region. It sheds some light on the seasonal evolution of ozone at low latitudes, as influenced by tides.

  9. The thermospheric auroral red line polarization: confirmation of detection and first quantitative analysis

    Directory of Open Access Journals (Sweden)

    Moen Joran

    2013-01-01

    Full Text Available The thermospheric atomic oxygen red line is among the brightest in the auroral spectrum. Previous observations in Longyearbyen, Svalbard, indicated that it may be intrinsically polarized, but a possible contamination by light pollution could not be ruled out. During the winter 2010/2011, the polarization of the red line was measured for the first time at the Polish Hornsund polar base without contamination. Two methods of data analysis are presented to compute the degree of linear polarization (DoLP and angle of linear polarization (AoLP: one is based on averaging and the other one on filtering. Results are compared and are in qualitative agreement. For solar zenith angles (SZA larger than 108° (with no contribution from Rayleigh scattering, the DoLP ranges between 2 and 7%. The AoLP is more or less aligned with the direction of the magnetic field line, in agreement with the theoretical predictions of Bommier et al. (2010. However, the AoLP values range between ±20° around this direction, depending on the auroral conditions. Correlations between the polarization parameters and the red line intensity I were considered. The DoLP decreases when I increases, confirming a trend observed during the observations in Longyearbyen. However, for small values of I, DoLP varies within a large range of values, while for large values of I, DoLP is always small. The AoLP also varies with the red line intensity, slightly rotating around the magnetic field line.

  10. Infrared response of the thermosphere-ionosphere system to geomagnetic storms

    Science.gov (United States)

    Thayer, J. P.; Mlynczak, M. G.; Hunt, L. A.; Russell, J. M., III

    2015-12-01

    For 14 years the SABER instrument on the NASA TIMED satellite has been observing the radiative cooling of the thermosphere-ionosphere system associated with infrared emission by nitric oxide (NO) and carbon dioxide (CO2). From these observations a very clear picture of fundamental processes that control the thermal structure above 100 km has emerged. The radiative cooling is modulated by variations in solar UV irradiance and geomagnetic effects. A pronounced solar cycle variation in both NO and CO2 cooling is observed, and CO2 cooling dominates during solar minimum. Radiative cooling in the current maximum peaked in December 2014, nine months after the sunspot peak. On average, solar ultraviolet irradiance provides about 70% of the energy that results in cooling by NO and the remaining 30% arises from geomagnetic processes. The relative roles of irradiance and geomagnetism vary strongly over a solar cycle. Of particular interest are the large, short-term increases in radiative cooling associated with intense geomagnetic storms. The large energy deposition heats the atmosphere and the infrared cooling increases non-linearly, helping the atmosphere to shed the storm energy and rapidly return to pre-storm conditions. This "natural thermostat" effect of infrared radiation will be shown in detail in this talk, as a function of latitude and altitude for a number of different geomagnetic storms. The relative roles of radiative cooling by NO and CO2 will also be investigated, to see if there is any storm-dependent preference. Finally, the sensitivity of the NO cooling to geomagnetic processes suggests that near real time observations of NO emission may serve as a forecasting tool for space weather. Increases in NO infrared emissions are associated with energy deposition and heating of the atmosphere. Observations of NO emission may then identify regions in which atmospheric drag is increasing, and thus may be a tool for now casting of drag for space operations.

  11. The wintertime two-day wave in the polar stratosphere, mesosphere and lower thermosphere

    Directory of Open Access Journals (Sweden)

    D. J. Sandford

    2008-02-01

    Full Text Available Recent observations of the polar mesosphere have revealed that waves with periods near two days reach significant amplitudes in both summer and winter. This is in striking contrast to mid-latitude observations where two-day waves maximise in summer only. Here, we use data from a meteor radar at Esrange (68° N, 21° E in the Arctic and data from the MLS instrument aboard the EOS Aura satellite to investigate the wintertime polar two-day wave in the stratosphere, mesosphere and lower thermosphere. The radar data reveal that mesospheric two-day wave activity measured by horizontal-wind variance has a semi-annual cycle with maxima in winter and summer and equinoctial minima. The MLS data reveal that the summertime wave in the mesosphere is dominated by a westward-travelling zonal wavenumber three wave with significant westward wavenumber four present. It reaches largest amplitudes at mid-latitudes in the southern hemisphere. In the winter polar mesosphere, however, the wave appears to be an eastward-travelling zonal wavenumber two, which is not seen during the summer. At the latitude of Esrange, the eastward-two wave reaches maximum amplitudes near the stratopause and appears related to similar waves previously observed in the polar stratosphere. We conclude that the wintertime polar two-day wave is the mesospheric manifestation of an eastward-propagating, zonal-wavenumber-two wave originating in the stratosphere, maximising at the stratopause and likely to be generated by instabilities in the polar night jet.

  12. Modeling Weather in the Ionosphere using the Navy's Highly Integrated Thermosphere and Ionosphere Demonstration System (HITIDES)

    Science.gov (United States)

    McDonald, S. E.; Sassi, F.; Zawdie, K.; McCormack, J. P.; Coker, C.; Huba, J.; Krall, J.

    2016-12-01

    The Naval Research Laboratory (NRL) has recently developed a ground-to-space atmosphere-ionosphere prediction capability, the Highly Integrated Thermosphere and Ionosphere Demonstration System (HITIDES). HITIDES is the U.S. Navy's first coupled, physics-based, atmosphere-ionosphere model, one in which the atmosphere extends from the ground to the exobase ( 500 km altitude) and the ionosphere reaches several 10,000 km in altitude. HITIDES has been developed by coupling the extended version of the Whole Atmosphere Community Climate Model (WACCM-X) with NRL's ionospheric model, Sami3 is Another Model of the Ionosphere (SAMI3). Integrated into this model are the effects of drivers from atmospheric weather (day-to-day meteorology), the Sun, and the changing high altitude composition. To simulate specific events, HITIDES can be constrained by data analysis products or observations. We have performed simulations of the ionosphere during January-February 2010 in which lower atmospheric weather patterns have been introduced using the Navy Operational Global Atmospheric Prediction System-Advanced Level Physics High Altitude (NOGAPS-ALPHA) data assimilation products. The same time period has also been simulated using the new atmospheric forecast model, the NAVy Global Environmental Model (NAVGEM), which has replaced NOGAPS-ALPHA. The two simulations are compared with each other and with observations of the low latitude ionosphere. We will discuss the importance of including lower atmospheric meteorology in ionospheric simulations to capture day-to-day variability as well as large-scale longitudinal structure in the low-latitude ionosphere. In addition, we examine the effect of the variability on HF radio wave propagation by comparing simulated ionograms calculated from the HITIDES ionospheric specifications to ionosonde measurements.

  13. Medium-scale gravity wave activity in the thermosphere inferred from GOCE data

    Science.gov (United States)

    Garcia, Raphael F.; Bruinsma, Sean; Massarweh, Lotfi; Doornbos, Eelco

    2016-08-01

    This study is focused on the effect of solar flux conditions on the dynamics of gravity waves (GWs) in the thermosphere. Air density and crosswind in situ estimates from the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) accelerometers are analyzed for the whole mission duration. The analysis is performed in the Fourier spectral domain averaging spectral results over periods of 2 months close to solstices. A new GW marker (called Cf3) is introduced here to characterize GWs activity under low, medium, and high solar flux conditions, showing a clear solar damping effect on GW activity. Most GW signal is found in a spectral range above 8 mHz in GOCE data, meaning a maximum horizontal wavelength of around 1000 km. The level of GW activity at GOCE altitude is strongly decreasing with increasing solar flux. Furthermore, a shift in the dominant frequency with solar flux conditions has been noted, leading to larger horizontal wavelengths (from 200 to 500 km) during high solar flux conditions. The correlation between air density variability and GW marker allows to identify most of the large-amplitude perturbations below 67° latitudes as due to GWs. The influence of correlated error sources, between air density and crosswinds, is discussed. Consistency of the spectral domain results is verified in the time domain with a global mapping of high-frequency air density perturbations along the GOCE orbit. This analysis shows a clear dependence with geomagnetic latitude with strong perturbations at magnetic poles and an extension to lower latitudes favored by low solar activity conditions. These results are consistent with previous Challenging Minisatellite Payload (CHAMP) data analysis and with general circulation models.

  14. Planet-B: A Japanese Mars aeronomy observer

    Science.gov (United States)

    Tsuruda, K.

    1992-01-01

    An introduction is given to a Japanese Mars mission (Planet-B) which is being planned at the Institute of Space and Aeronautical Science (ISAS), Japan. Planet-B aims to study the upper atmosphere of Mars and its interaction with the solar wind. The launch of Planet-B is planned for 1996 on a new launcher, M-L, which is being developed at ISAS. In addition to the interaction with the solar wind, the structure of the Martian upper atmosphere is thought to be controlled by the meteorological condition in the lower atmosphere. The orbit of Planet-B was chosen so that it will pass two important regions, the region where the solar wind interacts with the Martian upper atmosphere and the tail region where ion acceleration is taking place. Considering the drag due to the Martian atmosphere, the periapsis altitude of 150 km and apoapsis of 10 Martian radii are planned. The orbit plane will be nearly parallel to the ecliptic plane. The altitude of the spacecraft will be spin stabilized and its spin axis will be controlled to the point of the earth. The dry weight of the spacecraft will be about 250 kg, including the scientific payload which consists of a magnetometer, plasma instruments, HF sounder, UV imaging spectrometer, and lower atmosphere monitor.

  15. Mars at Ls 93o: Syrtis Major

    Science.gov (United States)

    2006-01-01

    15 August 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 93o during a previous Mars year. This month, Mars looks similar, as Ls 93o occurs in mid-August 2006. The picture shows the Syrtis Major face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Summer/Southern Winter

  16. Mars at Ls 249o: Tharsis

    Science.gov (United States)

    2005-01-01

    5 July 2005 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 249o during a previous Mars year. This month, Mars looks similar, as Ls 249o occurs in mid-July 2005. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Autumn/Southern Spring

  17. Mars at Ls 53o: Tharsis

    Science.gov (United States)

    2006-01-01

    2 May 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 53o during a previous Mars year. This month, Mars looks similar, as Ls 53o occurs in mid-May 2006. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring/Southern Autumn

  18. Mars at Ls 79o: Syrtis Major

    Science.gov (United States)

    2006-01-01

    18 July 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 79o during a previous Mars year. This month, Mars looks similar, as Ls 79o occurs in mid-July 2006. The picture shows the Syrtis Major face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring/Southern Autumn

  19. Mars at Ls 269o: Tharsis

    Science.gov (United States)

    2005-01-01

    2 August 2005 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 269o during a previous Mars year. This month, Mars looks similar, as Ls 269o occurs in mid-August 2005. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: last days of Northern Autumn/Southern Spring

  20. Mars at Ls 12o: Tharsis

    Science.gov (United States)

    2006-01-01

    7 February 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 12o during a previous Mars year. This month, Mars looks similar, as Ls 12o occurs in mid-February 2006. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Winter/Southern Summer

  1. Mars at Ls 25o: Syrtis Major

    Science.gov (United States)

    2006-01-01

    21 March 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 25o during a previous Mars year. This month, Mars looks similar, as Ls 25o occurs in mid-March 2006. The picture shows the Syrtis Major face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring

  2. Mars at Ls 79o: Tharsis

    Science.gov (United States)

    2006-01-01

    4 July 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 79o during a previous Mars year. This month, Mars looks similar, as Ls 79o occurs in mid-July 2006. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring/Southern Autumn

  3. Mars at Ls 306o: Tharsis

    Science.gov (United States)

    2005-01-01

    4 October 2005 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 306o during a previous Mars year. This month, Mars looks similar, as Ls 306o occurs in mid-October 2005. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Winter/Southern Summer

  4. Mars at Ls 357o: Tharsis

    Science.gov (United States)

    2006-01-01

    4 January 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 357o during a previous Mars year. This month, Mars looks similar, as Ls 357o occurs in mid-January 2006. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. NASA/JPL/Malin Space Science SystemsSeason: Northern Winter/Southern Summer

  5. Mars at Ls 66o: Tharsis

    Science.gov (United States)

    2006-01-01

    6 June 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 66o during a previous Mars year. This month, Mars looks similar, as Ls 66o occurs in mid-June 2006. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring/Southern Autumn

  6. Mars at Ls 53o: Syrtis Major

    Science.gov (United States)

    2006-01-01

    16 May 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 53o during a previous Mars year. This month, Mars looks similar, as Ls 53o occurs in mid-May 2006. The picture shows the Syrtis Major face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring/Southern Autumn

  7. Mars at Ls 341o: Tharsis

    Science.gov (United States)

    2005-01-01

    6 December 2005 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 341o during a previous Mars year. This month, Mars looks similar, as Ls 341o occurs in mid-December 2005. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Winter/Southern Summer

  8. Mars at Ls 25o: Tharsis

    Science.gov (United States)

    2006-01-01

    7 March 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 25o during a previous Mars year. This month, Mars looks similar, as Ls 25o occurs in mid-March 2006. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring/Southern Autumn

  9. Mars at Ls 93o: Tharsis

    Science.gov (United States)

    2006-01-01

    1 August 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 93o during a previous Mars year. This month, Mars looks similar, as Ls 93o occurs in mid-August 2006. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Summer/Southern Winter

  10. Mars at Ls 12o: Syrtis Major

    Science.gov (United States)

    2006-01-01

    21 February 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 12o during a previous Mars year. This month, Mars looks similar, as Ls 12o occurs in mid-February 2006. The picture shows the Syrtis Major face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Winter/Southern Summer

  11. Mars at Ls 39o: Syrtis Major

    Science.gov (United States)

    2006-01-01

    18 April 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 39o during a previous Mars year. This month, Mars looks similar, as Ls 39o occurs in mid-April 2006. The picture shows the Syrtis Major face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring/Southern Autumn

  12. Mars at Ls 39o: Tharsis

    Science.gov (United States)

    2006-01-01

    4 April 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 39o during a previous Mars year. This month, Mars looks similar, as Ls 39o occurs in mid-April 2006. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring/Southern Autumn

  13. Mars at Ls 324o: Tharsis

    Science.gov (United States)

    2005-01-01

    1 November 2005 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 324o during a previous Mars year. This month, Mars looks similar, as Ls 324o occurs in mid-November 2005. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Winter/Southern Summer

  14. Mars at Ls 288o: Tharsis

    Science.gov (United States)

    2005-01-01

    6 September 2005 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 288o during a previous Mars year. This month, Mars looks similar, as Ls 288o occurs in mid-September 2005. The picture shows the Tharsis face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Winter/Southern Summer

  15. Mars at Ls 66o: Syrtis Major

    Science.gov (United States)

    2006-01-01

    20 June 2006 This picture is a composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images acquired at Ls 66o during a previous Mars year This month, Mars looks similar, as Ls 66o occurs in mid-June 2006. The picture shows the Syrtis Major face of Mars. Over the course of the month, additional faces of Mars as it appears at this time of year are being posted for MOC Picture of the Day. Ls, solar longitude, is a measure of the time of year on Mars. Mars travels 360o around the Sun in 1 Mars year. The year begins at Ls 0o, the start of northern spring and southern autumn. Season: Northern Spring/Southern Autumn

  16. Site Selection for Mars Exopaleontology in 2001

    Science.gov (United States)

    Farmer, Jack

    1998-01-01

    hydrothermal deposits formed below the upper temperature limit for life (about 160 degrees C). There are many sites within the present latitudinal constraints for the 2001 mission (15 deg S to 30 deg N) that meet these requirements. But the practical problem with these kinds of deposits is that they tend to be disseminated, making up only a small percentage of a host rock. Even with mineralogical information provided by the Thermal Emission Spectrometer (TES) presently in orbit around Mars, predicting their occurrence ahead of time may be quite difficult. The deposits of surficial aqueous sedimentary systems are likely to provide the largest targets for site selection in 2001. Of these, the deposits of hydrothermal systems (subaerial and subaqueous thermal springs) have been discussed previously. It is likely that hydrothermal systems were widespread on Mars early in its history and a number of common geo-tectonic settings on Mars are likely to have hosted hydrothermal activity. Most of these are represented within the latitudinal constraints presently identified for 2001. However, the deposits of surface spring systems are likely to be difficult to find as well. On Earth, exposure areas for hydrothermal spring mounds are typically a few square kms, less than a single TES pixel. But such deposits may be quite abundant within some volcanic terrains, It is estimated, for example, that between 15-20% of the floor of Yellowstone caldera is covered by thermal spring deposits. In such abundances, subaerial sinters could well be detected by TES. Where exposed, the shallow subsurface portions of these systems may be quite a lot larger (perhaps tens of square kms), although (as noted above) mineralization may be finely disseminated in the basement rock, making remote detection more difficult. Paleolake Basins. There are a large number of potential paleolake basins on Mars (inclusive of impact craters and volcanic calderas) that have been previously identified using Viking images. Most

  17. Site Selection for Mars Exopaleontology in 2001

    Science.gov (United States)

    Farmer, Jack

    1998-01-01

    hydrothermal deposits formed below the upper temperature limit for life (about 160 degrees C). There are many sites within the present latitudinal constraints for the 2001 mission (15 deg S to 30 deg N) that meet these requirements. But the practical problem with these kinds of deposits is that they tend to be disseminated, making up only a small percentage of a host rock. Even with mineralogical information provided by the Thermal Emission Spectrometer (TES) presently in orbit around Mars, predicting their occurrence ahead of time may be quite difficult. The deposits of surficial aqueous sedimentary systems are likely to provide the largest targets for site selection in 2001. Of these, the deposits of hydrothermal systems (subaerial and subaqueous thermal springs) have been discussed previously. It is likely that hydrothermal systems were widespread on Mars early in its history and a number of common geo-tectonic settings on Mars are likely to have hosted hydrothermal activity. Most of these are represented within the latitudinal constraints presently identified for 2001. However, the deposits of surface spring systems are likely to be difficult to find as well. On Earth, exposure areas for hydrothermal spring mounds are typically a few square kms, less than a single TES pixel. But such deposits may be quite abundant within some volcanic terrains, It is estimated, for example, that between 15-20% of the floor of Yellowstone caldera is covered by thermal spring deposits. In such abundances, subaerial sinters could well be detected by TES. Where exposed, the shallow subsurface portions of these systems may be quite a lot larger (perhaps tens of square kms), although (as noted above) mineralization may be finely disseminated in the basement rock, making remote detection more difficult. Paleolake Basins. There are a large number of potential paleolake basins on Mars (inclusive of impact craters and volcanic calderas) that have been previously identified using Viking images. Most

  18. The ExoMars 2016 Mission arriving at Mars

    Science.gov (United States)

    Svedhem, H.; Vago, J. L.

    2016-12-01

    The ExoMars 2016 mission was launched on a Proton rocket from Baikonur, Kazakhstan, on 14 March 2016 and is scheduled to arrive at Mars on 19 October 2016. ExoMars is a joint programme of the European Space Agency (ESA) and Roscosmos, Russia. It consists of the ExoMars 2016 mission with the Trace Gas Orbiter, TGO, and the Entry Descent and Landing Demonstrator, EDM, named Schiaparelli, and the ExoMars 2020 mission, which carries a lander and a rover. The TGO scientific payload consists of four instruments. These are: ACS and NOMAD, both infrared spectrometers for atmospheric measurements in solar occultation mode and in nadir mode, CASSIS, a multichannel camera with stereo imaging capability, and FREND, an epithermal neutron detector to search for subsurface hydrogen (as proxy for water ice and hydrated minerals). The mass of the TGO is 3700 kg, including fuel. The EDM, with a mass of 600 kg, is mounted on top of the TGO as seen in its launch configuration. The EDM is carried to Mars by the TGO and is separated three days before arrival at Mars. In addition to demonstrating the landing capability two scientific investigations are included with the EDM. The AMELIA investigation aims at characterising the Martian atmosphere during the entry and descent using technical and engineering sensors of the EDM, and the DREAMS suite of sensors that will characterise the environment of the landing site for a few days after the landing. ESA provides the TGO spacecraft and the Schiaparelli Lander demonstrator, ESA member states provide two of the TGO instruments and Roscosmos provides the launcher and the other two TGO instruments. After the arrival of the ExoMars 2020 mission at the surface of Mars, the TGO will handle all communications between the Earth and the Rover. The communication between TGO and the rover/lander is done through a UHF communications system, a contribution from NASA. This presentation will cover a description of the 2016 mission, including the spacecraft

  19. [Upper extremity arterial diseases].

    Science.gov (United States)

    Becker, F

    2007-02-01

    Compared to lower limb arterial diseases, upper limb arterial diseases look rare, heterogeneous with various etiologies and a rather vague clinical picture, but with a negligible risk of amputation. Almost all types of arterial diseases can be present in the upper limb, but the anatomical and hemodynamic conditions particular to the upper limb often confuse the issue. Thus, atherosclerosis affects mainly the subclavian artery in its proximal segment where the potential of collateral pathway is high making the symptomatic forms not very frequent whereas the prevalence of subclavian artery stenosis or occlusion is relatively high. The clinical examination and the etiologies are discussed according to the clinical, anatomical and hemodynamic context.

  20. Nitrogen on Mars: Insights from Curiosity

    Science.gov (United States)

    Stern, J. C.; Sutter, B.; Jackson, W. A.; Navarro-Gonzalez, Rafael; McKay, Chrisopher P.; Ming, W.; Archer, P. Douglas; Glavin, D. P.; Fairen, A. G.; Mahaffy, Paul R.

    2017-01-01

    Recent detection of nitrate on Mars indicates that nitrogen fixation processes occurred in early martian history. Data collected by the Sample Analysis at Mars (SAM) instrument on the Curiosity Rover can be integrated with Mars analog work in order to better understand the fixation and mobility of nitrogen on Mars, and thus its availability to putative biology. In particular, the relationship between nitrate and other soluble salts may help reveal the timing of nitrogen fixation and post-depositional behavior of nitrate on Mars. In addition, in situ measurements of nitrogen abundance and isotopic composition may be used to model atmospheric conditions on early Mars.