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  • 1. Barabash, Victoria
    et al.
    Chilson, P.
    Kirkwood, S.
    Réchou, A.
    Stebel, K.
    Investigations of the possible relationship between PMSE and tides using a VHF MST radar1998In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 25, no 17, p. 3297-3300Article in journal (Refereed)
  • 2.
    Behar, Etienne
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Nilsson, Hans
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Wieser, Gabriella Stenberg
    Swedish Institute of Space Physics.
    Nemeth, Zoltan
    Wigner Research Centre for Physics, 1121 Konkoly Thege Street 29-33, Budapest.
    Brolles, T.W.
    Space Science and Engineering Division, Southwest Research Institute, San Antonio.
    Richter, Ingo
    Technische Universität–Braunschweig, Institute for Geophysics and Extraterrestrial Physics.
    Mass loading at 67P/Churyumov-Gerasimenko: A case study2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 4, p. 1411-1418Article in journal (Refereed)
    Abstract [en]

    We study the dynamics of the interaction between the solar wind ions and a partially ionized atmosphere around a comet, at a distance of 2.88 AU from the Sun during a period of low nucleus activity. Comparing particle data and magnetic field data for a case study, we highlight the prime role of the solar wind electric field in the cometary ion dynamics. Cometary ion and solar wind proton flow directions evolve in a correlated manner, as expected from the theory of mass loading. We find that the main component of the accelerated cometary ion flow direction is along the antisunward direction and not along the convective electric field direction. This is interpreted as the effect of an antisunward polarization electric field adding up to the solar wind convective electric field.

  • 3. Buehler, Stefan
    et al.
    Courcoux, N.
    Universität Bremen, Institute of Environmental Physics.
    The impact of temperature errors on perceived humidity supersaturation2003In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 30, no 14, p. 1759-Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo method is used to study the propagation of temperature uncertainties into relative humidity with respect to ice (RH i ) calculated from specific humidity. For a flat specific humidity distribution and Gaussian temperature uncertainties the resulting RH i distribution drops exponentially at high RH i values—much slower than a Gaussian. This agrees well with the RH i distribution measured by the Microwave Limb Sounder (MLS), which means that such remotely measured RH i distributions can be explained, at least partly, by temperature uncertainties.

  • 4. Buehler, Stefan
    et al.
    Kuvatov, M.
    Universität Bremen, Institute of Environmental Physics.
    John, V. O.
    Universität Bremen, Institute of Environmental Physics.
    Scan asymmetries in AMSU-B data2005In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 32, no 24, p. L2481-Article in journal (Refereed)
    Abstract [en]

    A simple method of averaging measurements for different scan positions was used to quantify scan asymmetries in AMSU-B brightness temperatures for the sensors on the satellites NOAA 15, 16, and 17. The method works particularly well for the sounding channels 18 to 20. The asymmetries are small in most cases. In particular, asymmetries for Channel 18 are below 1.90, −0.53, and 0.49 K for NOAA 15, 16, and 17, respectively. On the other hand, it was found that the instrument on NOAA 15 has significant asymmetries for Channels 19 and 20, which seem to be related to the known radio frequency interference problem for this instrument. The use of the appropriate set of interference correction coefficients significantly reduces the asymmetry.

  • 5.
    Dhanaya, M.B.
    et al.
    Space Physics Laboratory, Vikram Sarabhai Space Center, Trivandrum.
    Bhardwaj, A.
    Space Physics Laboratory, Vikram Sarabhai Space Center, Trivandrum.
    Futaana, Y.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Fatemi, Shahab
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Holmström, M.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Barabash, Stas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Wieser, M.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Wurz, P.
    Physikalisches Institut, University of Bern.
    Thampi, R.S.
    Space Physics Laboratory, Vikram Sarabhai Space Center, Trivandrum.
    Proton entry into the near-lunar plasma wake for magnetic field aligned flow2013In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 2, p. 2913-2917Article in journal (Refereed)
    Abstract [en]

    We report the first observation of protons in the near-lunar (100–200 km from the surface) and deeper (near anti-subsolar point) plasma wake when the interplanetary magnetic field (IMF) and solar wind velocity (vsw) are parallel (aligned flow; angle between IMF and vsw≤10°). More than 98% of the observations during aligned flow condition showed the presence of protons in the wake. These observations are obtained by the Solar Wind Monitor sensor of the Sub-keV Atom Reflecting Analyser experiment on Chandrayaan-1. The observation cannot be explained by the conventional fluid models for aligned flow. Back tracing of the observed protons suggests that their source is the solar wind. The larger gyroradii of the wake protons compared to that of solar wind suggest that they were part of the tail of the solar wind velocity distribution function. Such protons could enter the wake due to their large gyroradii even when the flow is aligned to IMF. However, the wake boundary electric field may also play a role in the entry of the protons into the wake.

  • 6.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Recording marine airgun shots at offsets between 300 and 700 km1991In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 18, no 4, p. 645-648Article in journal (Refereed)
    Abstract [en]

    This paper demonstrates that - under favorable conditions - by using multichannel recording and subsequent stacking of adjacent records marine airgun shots have been detected at offset distances up to 700 km, the maximum offset at which the authors attempted to record data.^Besides a powerful airgun array, a low noise environment at the recording site and the elimination of static shifts are the prerequisites to obtain refracted and reflected arrivals from the crust and upper mantle at such large offsets.^Primary arrivals detected at offsets between 400 and 700 km image the upper mantle from 70 to about 120 km depth.^Stacking of neighboring shots and/or receivers successfully increases the signal-to-noise ratio, if the traces have been corrected for offset differences, which requires knowledge of the apparent phase velocities.^The data presented here were collected in autumn 1989 during the BABEL Project on the Baltic Shield.

  • 7.
    Engeln, Axel von
    et al.
    Universität Bremen, Institute of Environmental Physics.
    Buehler, Stefan
    Kirchengast, Gottfried
    University of Graz, Institute for Geophysics, Astrophysics and Meteorology.
    Kuenzi, Klaus
    Universität Bremen, Institute of Environmental Physics.
    Temperature profile retrieval from surface to mesopause by combining GNSS radio occultation and passive microwave limb sounder data2001In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 28, no 5, p. 775-778Article in journal (Refereed)
    Abstract [en]

    A theoretical study on the combination of a passive microwave and a GNSS radio occultation instrument, mounted on the International Space Station (ISS), was performed. Both instruments allow to deduce the atmospheric temperature profile. We combined realistically simulated data of the two highly synergistic sensors with the optimal estimation method (OEM) and retrieved single joint temperature profiles from 0 to 90 km altitude for which we found accuracies < 1 K below 35 km and < 4 K in the mesosphere, respectively. In addition, we performed simultaneous tropospheric water vapor and temperature retrievals leading to a water vapor accuracy < 10 to 20 % at altitudes below 5 to 8 km. The OEM allows to optimally exploit the synergy in the data and maximizes retrieval accuracy over the full range from surface to mesopause. It seems worthwhile to install this type of instrument combination on the ISS or other low-Earth-orbit (LEO) platforms.

  • 8.
    Engeln, Axel von
    et al.
    Meteorological Division, European Organization for the Exploitation of Meteorological Satellites, Darmstadt.
    Teixeira, Joao
    NATO Undersea Research Centre, La Spezia.
    Wickert, Jens
    GeoForschungsZentrum Potsdam.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Comment on "Monitoring the atmospheric boundary layer by GPS radio occultation signals recorded in the open-loop mode" by S. Sokolovskiy et al.2007In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 34, no 2, p. L02806-Article in journal (Other academic)
  • 9.
    Engeln, Axel von
    et al.
    UK Met Office, Exeter.
    Teixeira, Joao
    Marine Meteorology Division, Naval Research Laboratory, Monterey, California.
    Wickert, Jens
    GeoForschungsZentrum Potsdam, Department of Geodesy and Remote Sensing, Potsdam.
    Buehler, Stefan
    Using CHAMP radio occultation data to determine the top altitude of the planetary boundary layer2005In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 32, no 6, p. L06815-Article in journal (Refereed)
    Abstract [en]

    A simple approach to derive the Planetary Boundary Layer (PBL) top altitude from CHAMP (CHAllenging Minisatellite Payload) radio occultation (RO) data is presented. Our RO processing cuts off at an altitude, typically ≤4 km, below which the GPS signals are affected by tracking errors. This lowest processed altitude (LPA) is assumed to coincide with the PBL top. We average LPAs for the years 2001 to 2004 over 5 Degree latitude longitude boxes and compare them to ECMWF analysis data. The ECMWF PBL top was calculated from the relative humidity gradient with respect to altitude. Agreement between the data sets is good in terms of mean PBL height, especially over sea. The CHAMP data shows the major features of PBL height with a realistic transition from stratocumulus regions to shallow and deep cumulus areas. CHAMP also shows a substantial amount of PBL height variability that may prove useful to study PBL dynamics.

  • 10.
    Fatemi, Shahab
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Holmström, Mats
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Futaana, Yoshifumi
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Barabash, Stas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Lue, Charles
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    The lunar wake current systems2013In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 1, p. 17-21Article in journal (Refereed)
    Abstract [en]

    We present the lunar wake current systems when the Moon is assumed to be a non-conductive body, absorbing the solar wind plasma. We show that in the transition regions between the plasma void, the expanding rarefaction region, and the interplanetary plasma, there are three main currents flowing around these regions in the lunar wake. The generated currents induce magnetic fields within these regions and perturb the field lines there. We use a three-dimensional, self-consistent hybrid model of plasma (particle ions and fluid electrons) to show the flow of these three currents. First, we identify the different plasma regions, separated by the currents, and then we show how the currents depend on the interplanetary magnetic field direction. Finally, we discuss the current closures in the lunar wake.

  • 11.
    Guzewich, Scott D.
    et al.
    NASA Goddard Spaceflight Center,Greenbelt, MD, USA.
    Lemmon, M.
    Space Science Institute, College Station, TX, USA.
    Smith, C.L
    Department of Earth and Space Science and Engineering, York University, Toronto, Ontario, Canada.
    Martínez, G.
    College of Engineering, University of Michigan, Ann Arbor, MI, USA.
    de Vicente‐Retortillo, Á.
    College of Engineering, University of Michigan, Ann Arbor, MI, USA.
    Newman, C. E.
    Aeolis Research, Pasadena, CA, USA.
    Baker, M.
    Department of Earth and Planetary Science, The Johns Hopkins University, Baltimore, MD, USA.
    Campbell, C.
    Department of Earth and Space Science and Engineering, York University, Toronto, Ontario, Canada.
    Cooper, B.
    Department of Earth and Space Science and Engineering, York University, Toronto, Ontario, Canada.
    Gómez‐Elvira, J.
    Centro de Astrobiología (INTA-CSIC), Madrid, Spain.
    Harri, A.‐M.
    Finnish Meteorological Institute, Helsinki, Finland.
    Hassler, D.
    Southwest Research Institute, Boulder, CO, USA.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Instituto Andaluz de Ciencias de la Tierra (CSIC‐UGR), Armilla, Granada, Spain.
    McConnochie, T.
    Department of Astronomy, University of Maryland, College Park, MD, USA.
    Moores, J. E.
    Department of Earth and Space Science and Engineering, York University, Toronto, Ontario, Canada.
    Kahanpää, H.
    Finnish Meteorological Institute, , Helsinki, Finland; School of Electrical Engineering, Aalto University, , Espoo, Finland.
    Khayat, A.
    NASA Goddard Spaceflight Center, Greenbelt, MD, USA;CRESST II and Department of Astronomy, University of Maryland, College Park, MD, USA.
    Richardson, M. I.
    Aeolis Research, Pasadena, CA, USA.
    Smith, M.D
    NASA Goddard Spaceflight Center, Greenbelt, MD, USA.
    Sullivan, R.
    Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY, USA.
    de la Torre Juarez, M.
    Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY, USA.
    Vasavada, A.R
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.
    Viúdez‐Moreiras, D.
    Centro de Astrobiología (INTA-CSIC), Madrid, Spain.
    Zeitlin, C.
    Leidos, Houston, TX, USA.
    Zorzano Mier, María-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Mars Science Laboratory Observations of the 2018/Mars Year 34 Global Dust Storm2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 1, p. 71-79Article in journal (Refereed)
    Abstract [en]

    Mars Science Laboratory Curiosity rover observations of the 2018/Mars year 34 global/planet‐encircling dust storm represent the first in situ measurements of a global dust storm with dedicated meteorological sensors since the Viking Landers. The Mars Science Laboratory team planned and executed a science campaign lasting approximately 100 Martian sols to study the storm involving an enhanced cadence of environmental monitoring using the rover's meteorological sensors, cameras, and spectrometers. Mast Camera 880‐nm optical depth reached 8.5, and Rover Environmental Monitoring Station measurements indicated a 97% reduction in incident total ultraviolet solar radiation at the surface, 30K reduction in diurnal range of air temperature, and an increase in the semidiurnal pressure tide amplitude to 40 Pa. No active dust‐lifting sites were detected within Gale Crater, and global and local atmospheric dynamics were drastically altered during the storm. This work presents an overview of the mission's storm observations and initial results.

  • 12.
    Höpfner, M.
    et al.
    Karlsruhe Institute of Technology.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Orphal, J.
    Karlsruhe Institute of Technology.
    Stiller, G.
    Karlsruhe Institute of Technology.
    The natural greenhouse effect of atmospheric oxygen (O2) and nitrogen (N2)2012In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 39, p. L10706-Article in journal (Refereed)
    Abstract [en]

    The effect of collision-induced absorption by molecular oxygen (O 2) and nitrogen (N 2) on the outgoing longwave radiation (OLR) of the Earth's atmosphere has been quantified. We have found that on global average under clear-sky conditions the OLR is reduced due to O 2 by 0.11 Wm -2 and due to N 2 by 0.17 Wm -2. Together this amounts to 15% of the OLR-reduction caused by CH 4 at present atmospheric concentrations. Over Antarctica the combined effect of O 2 and N 2 increases on average to about 38% of CH 4 with single values reaching up to 80%. This is explained by less interference of H 2O spectral bands on the absorption features of O 2 and N 2 for dry atmospheric conditions

  • 13.
    John, V. O.
    et al.
    Universität Bremen, Institute of Environmental Physics.
    Buehler, Stefan
    The impact of ozone lines on AMSU-B radiances2004In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 31, no 21, p. L21108-Article in journal (Refereed)
    Abstract [en]

    The impact of ozone lines on Advanced Microwave Sounding Unit-B (AMSU-B) radiances was investigated using a line-by-line radiative transfer model. The impact is found to be the largest for channel 18 (183.31 ± 1.00 GHz), with a maximum up to about 0.5 K. The channels 17 (150 GHz) and 20 (183.31 ± 7.00 GHz) are also marginally affected by the ozone lines. The magnitude of the impact shows an interesting dependence on the channel 18 brightness temperature which implies that the effect is not just an offset to the brightness temperature.

  • 14. Kirkwood, S.
    et al.
    Barabash, Victoria
    Brändström, B.U.E.
    Moström, A.
    Stebel, K.
    Mitchell, N.
    Hocking, W.
    Noctilucent clouds, PMSE and 5-day planetary waves: a case study2002In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 29, no 10, p. 1-4Article in journal (Refereed)
  • 15. Kirkwood, S.
    et al.
    Barabash, Victoria
    Chilson, P.
    Réchou, A.
    Stebel, K.
    Espy, P.
    Witt, G.
    Stegman, J.
    The 1997 PMSE season - its relation to wind, temperature and water vapor1998In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 25, no 11, p. 1867-1870Article in journal (Refereed)
  • 16.
    Lanza, Nina L.
    et al.
    Los Alamos National Laboratory.
    Wiens, Roger C.
    Los Alamos National Laboratory, Space Remote Sensing, Los Alamos National Laboratory, Los Alamos, International Space and Response Division, Los Alamos National Laboratory.
    Arvidson, Ray E.
    Washington University, St. Louis.
    Clark, Benton C.
    Space Science Institute, Boulder, Colorado, Space Science Institute.
    Fischer, W.W.
    California Institute of Technology, Pasadena.
    Gellert, Ralf
    University of Guelph, Ontario, University of Guelph, Department of Physics, University of Guelph, Ontario.
    Grotzinger, John P.
    California Institute of Technology, Pasadena, Division of Geological and Planetary Sciences, California Institute of Technology, Caltech, Pasadena, Jet Propulsion Laboratory, California Institute of Technology, Pasadena.
    Hurowitz, J.A.
    Department of Geosciences, Stony Brook University, Stony Brook University, NY, Department of Geosciences, State University of New York, Stony Brook.
    McLennan, S.M.
    Department of Geosciences, Stony Brook University, Stony Brook University, NY, Department of Geosciences, State University of New York, Stony Brook, The State University of New York, Stony Brook.
    Morris, R.V.
    NASA Johnson Space Center, NASA Johnson Space Center, Houston, Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, Houston.
    Rice, M.S.
    California Institute of Technology, Pasadena, Division of Geological and Planetary Sciences, California Institute of Technology.
    III, J.F. Bell
    Arizona State University, School of Earth and Space Exploration, Arizona State University, School of Earth and Space Exploration, Arizona State University, Tempe.
    Berger, Jeff A.
    University of Western Ontario, London.
    Blaney, Diana L.
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, Jet Propulsion Laboratory, Pasadena, Kalifornien.
    Bridges, Nathan T.
    Johns Hopkins University Applied Physics Laboratory, Laurel, Applied Physics Laboratory, Laurel, Maryland.
    Calef, Fred
    Jet Propulsion Laboratory, California Institute of Technology, Pasadena, Jet Propulsion Laboratory.
    Campbell, J.L.
    Department of Physics, University of Guelph, Ontario, University of Guelph, Ontario.
    Clegg, S.M.
    Los Alamos National Laboratory, Chemistry Division, Los Alamos National Laboratory.
    Cousin, A.
    Los Alamos National Laboratory, Chemistry Division, Los Alamos National Laboratory.
    Edgett, Kenneth S.
    Malin Space Science Systems, San Diego, Malin Space Science Systems.
    Fabre, Cécile
    Université de Lorraine, Nancy.
    Fisk, M.R.
    Oregon State University, Corvallis.
    Forni, Olivier
    IRAP/CNRS, Institut de Recherche en Astrophysique et Planetologie, Toulouse, Université de Toulouse, UPS-OMP, IRAP, Institut de Recherche en Astophysique et Planetologie (IRAP), Universite' Paul Sabatier, Toulouse, IRAP, CNRS/UPS, Toulouse.
    Frydenvang, J.
    Niels Bohr Institute, University of Copenhagen.
    Hardy, K.R.
    U.S. Naval Academy, Annapolis.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Zorzano Mier, Maria-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Oxidation of manganese in an ancient aquifer, Kimberley formation, Gale crater, Mars2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 14, p. 7398-7407Article in journal (Refereed)
    Abstract [en]

    The Curiosity rover observed high Mn abundances (>25wt % MnO) in fracture-filling materials that crosscut sandstones in the Kimberley region of Gale crater, Mars. The correlation between Mn and trace metal abundances plus the lack of correlation between Mn and elements such as S, Cl, and C, reveals that these deposits are Mn oxides rather than evaporites or other salts. On Earth, environments that concentrate Mn and deposit Mn minerals require water and highly oxidizing conditions; hence, these findings suggest that similar processes occurred on Mars. Based on the strong association between Mn-oxide deposition and evolving atmospheric dioxygen levels on Earth, the presence of these Mn phases on Mars suggests that there was more abundant molecular oxygen within the atmosphere and some groundwaters of ancient Mars than in the present day

  • 17.
    Larsson, Richard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Ramstad, Robin
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Mendrok, Jana
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Kasai, Yasuko
    National Institute of Information and Communications Technology, 4-2-1 Nukui-kitamachi, Koganei.
    A method for remote sensing of weak planetary magnetic fields: Simulated application to Mars2013In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 19, p. 5014-5018Article in journal (Refereed)
    Abstract [en]

    We present a method for characterizing the magnetic anomalies from the crustal fields in the lower atmosphere of Mars that requires two perpendicular linear polarization measurements of the Zeeman effect. The maximum effect of the magnetic field on the signal is found at the Doppler broadening width at low pressures rather than at the magnetically induced line frequency shift, and the effect strongly increases with increasing magnetic field strength. Based on simulations of the Zeeman-affected spectral cross section of the 119 GHz O2 line in a model Martian atmosphere at various magnetic field strengths, we conclude that it should be possible to probe the strength of the magnetic anomalies remotely with presently available technology. We discuss limitations of the method, how these results could be relevant to the interpretation of residuals in Herschel/HIFI observations of Mars, as well as the application to detection of exoplanetary magnetic fields.

  • 18.
    Lasue, J.
    et al.
    Université de Toulouse, Toulouse, France.
    Cousin, A.
    Université de Toulouse, Toulouse, France.
    Meslin, P.Y
    Université de Toulouse,Toulouse, France.
    Mangold, N.
    Université de Nantes, Nantes, France.
    Wiens, R.C
    Los Alamos National Laboratory, Los Alamos, NM, USA.
    Berger, G.
    Université de Toulouse,Toulouse, France.
    Dehouck, E.
    Université de Lyon, Villeurbanne, France.
    Forni, O.
    Université de Toulouse,Toulouse, France.
    Goetz, W.
    Max‐Planck‐Institut für Sonnensystemforschung, Göttingen, Germany.
    Gasnault, O.
    Université de Toulouse,Toulouse, France.
    Rapin, W.
    California Institute of Technology, Pasadena, CA, USA.
    Schroeder, S.
    German Aerospace Center (DLR), Institut für Optische Sensorsysteme, Berlin‐Adlershof, Germany.
    Ollila, A.
    Los Alamos National Laboratory, Los Alamos, NM, USA.
    Johnson, J.
    Johns Hopkins University APL, Laurel, MD, USA.
    Le Mouélic, S.
    Université de Nantes, Nantes, France.
    Maurice, S.
    Université de Toulouse, Toulouse, France.
    Anderson, R.
    USGS, Flagstaff, AZ, USA.
    Blaney, D.
    NASA JPL, Pasadena, CA, USA.
    Clark, B.
    Space Science Institute, Boulder, CO, USA.
    Clegg, S.M
    Los Alamos National Laboratory, Los Alamos, NM, USA.
    D'Uston, C.
    Université de Toulouse,Toulouse, France.
    Fabre, C.
    Lorraine University, Vandoeuvre, France.
    Lanza, N.
    Los Alamos National Laboratory, Los Alamos, NM, USA.
    Madsen, M.B
    Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
    Martin-Torres, Javier
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Melikechi, N.
    University of Massachusetts Lowell, Lowell, MA, USA.
    Newsom, H.
    University of New Mexico, Albuquerque, NM, USA.
    Sautter, V.
    Muséum d'Histoire Naturelle, Paris, France.
    Zorzano Mier, María-Paz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Centro de Astrobiología (INTA-CSIC), Torrejón de Ardoz, Spain.
    Martian Eolian Dust Probed by ChemCam2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 20, p. 10968-10977Article in journal (Refereed)
    Abstract [en]

    The ubiquitous eolian dust on Mars plays important roles in the current sedimentary and atmospheric processes of the planet. The ChemCam instrument retrieves a consistent eolian dust composition at the submillimeter scale from every first laser shot on Mars targets. Its composition presents significant differences with the Aeolis Palus soils and the Bagnold dunes as it contains lower CaO and higher SiO2. The dust FeO and TiO2contents are also higher, probably associated with nanophase oxide components. The dust spectra show the presence of volatile elements (S and Cl), and the hydrogen content is similar to Bagnold sands but lower than Aeolis Palus soils. Consequently, the dust may be a contributor to the amorphous component of soils, but differences in composition indicate that the two materials are not equivalent.

  • 19.
    Lue, Charles
    et al.
    Luleå tekniska universitet.
    Futaana, Yoshifumi
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Barabash, Stas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Wieser, Martin
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Holmström, Mats
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Bhardwaj, Anil
    Space Physics Laboratory, Vikram Sarabhai Space Center, Trivandrum.
    Dhanya, M.B.
    Space Physics Laboratory, Vikram Sarabhai Space Center, Trivandrum.
    Wurz, Peter
    Physikalisches Institut, University of Bern.
    Strong influence of lunar crustal fields on the solar wind flow2011In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 38, no 3Article in journal (Refereed)
    Abstract [en]

    We discuss the influence of lunar magnetic anomalies on the solar wind and on the lunar surface, based on maps of solar wind proton fluxes deflected by the magnetic anomalies. The maps are produced using data from the Solar WInd Monitor (SWIM) onboard the Chandrayaan-1 spacecraft. We find a high deflection efficiency (average ∼10%, locally ∼50%) over the large-scale (>1000 km) regions of magnetic anomalies. Deflections are also detected over weak (<3 nT at 30 km altitude) and small-scale (<100 km) magnetic anomalies, which might be explained by charge separation and the resulting electric potential. Strong deflection from a wide area implies that the magnetic anomalies act as a magnetosphere-like obstacle, affecting the upstream solar wind. It also reduces the implantation rate of the solar wind protons to the lunar surface, which may affect space weathering near the magnetic anomalies.

  • 20.
    Meissner, R.
    et al.
    Institut für Geophysik, Universität Kiel.
    Elming, Sten-åke
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Deep seismic survey images crustal structure of Tornquist Zone beneath southern Baltic Sea1991In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 18, no 6, p. 1091-1094Article in journal (Refereed)
    Abstract [en]

    The Tornquist Zone is Europe's longest tectonic lineament and bisects the continent in a NW-SE direction from the North Sea (off NW Denmark) to the Black Sea. New deep seismic reflection and coincident refraction data have been collected across its 50 km wide, intensely faulted and inverted NW part. The marine reflection profile in the area north of Bornholm Island shows a tilted block structure in the rigid upper crust, whereas the lower crust seems to be more gently uplifted. A complex transition from the highly reflective lower crust to the mantle is indicated by mantle reflections and a curious wide-angle event recorded by a landstation on Bornholm Island. We suggest that deep-reaching inversion tectonics, induced by Alpine and Carpathian orogeny, were responsible for the development of the gross crust-mantle structure of the Tornquist Zone in our study area, which seems to be similar to that in Poland.

  • 21. Milz, Mathias
    et al.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    John, V.O.
    Met Office Hadley Centre, Exeter.
    Comparison of AIRS and AMSU-B monthly mean estimates of upper tropospheric humidity2009In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 36, no L10804Article in journal (Refereed)
    Abstract [en]

    Satellite-borne measurements provide valuable information on the global distribution of upper tropospheric humidity (UTH), which represents the mean relative humidity in a layer approximately enclosed by the atmospheric pressure levels 500 and 200 hPa. Monthly mean distributions of microwave observations of UTH obtained from the Advanced Microwave Sounding Unit-B (AMSU-B) and the Humidity Sounder for Brazil (HSB) are compared to infrared observations of UTH from the Atmospheric Infrared Sounder (AIRS). All data sets for January 2003 show distributions as expected from climatologies. Data of AIRS and AMSU-B averaged on 1.5° × 1.5° lat-lon bins for January 2003 show good overall agreement. However, with 2.7%RH AIRS shows an unexpected wet mean bias, especially for regions where the influence of clouds is small or cloud affected measurements are excluded for both sensors. In regions where AIRS is sensitive to cloud affected measurements but not AMSU-B, the bias is reduced and partly negative.

  • 22.
    Mlynczak, Martin G.
    et al.
    NASA Langley Research Center.
    Martin-Torres, Javier
    Analytical Services and Materials Inc., Hampton.
    Mertens, Christopher J.
    NASA Langley Research Center.
    Marshall, B. Thomas
    G & A Technical Software.
    Thomspn, R. Earl
    G & A Technical Software.
    Kozyra, Janet U.
    Michigan University.
    Remsberg, Ellis E.
    NASA Langley Research Center.
    Gordley, Larry L.
    G & A Technical Software.
    Russell, James M.
    Hampton University.
    Woods, Thomas
    Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado.
    Solar-terrestrial coupling evidenced by periodic behavior in geomagnetic indexes and the infrared energy budget of the thermosphere2008In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 35, no 5, article id L05808Article in journal (Refereed)
    Abstract [en]

    We examine time series of the daily global power (W) radiated by carbon dioxide (at 15 μm) and by nitric oxide (at 5.3 μm) from the Earth's thermosphere between 100 km and 200 km altitude. Also examined is a time series of the daily absorbed solar ultraviolet power in the same altitude region in the wavelength span 0 to 175 run. The infrared data are derived from the SABER instrument and the solar data are derived from the SEE instrument, both on the NASA TIMED satellite. The time series cover nearly 5 years from 2002 through 2006. The infrared and solar time series exhibit a decrease in radiated and absorbed power consistent with the declining phase of the current 11-year solar cycle. The infrared time series also exhibits high frequency variations that are not evident in the solar power time series. Spectral analysis shows a statistically significant 9-day periodicity in the infrared data but not in the solar data. A very strong 9-day periodicity is also found to exist in the time series of daily Ap and Kp geomagnetic indexes. These 9-day periodicities are linked to the recurrence of coronal holes on the Sun. These results demonstrate a direct coupling between the upper atmosphere of the Sun and the infrared energy budget of the thermosphere. Copyright 2008 by the American Geophysical Union.

  • 23.
    Mlynczak, Marty
    et al.
    NASA Langley Research Center.
    Martin-Torres, Javier
    Analytical Services and Materials Inc., Hampton.
    Rusell, James
    Hampton University.
    Beaumont, Ken
    G & A Technical Software.
    Jacobson, Steven
    G & A Technical Software.
    Kozyra, Janet
    Michigan University.
    Lopez-Puertas, Manuel
    Instituto de Astrofísica de Andalucía CSIC, Granada.
    Funke, Bernd
    Instituto de Astrofísica de Andalucía CSIC, Granada.
    Mertens, Christopher
    NASA Langley Research Center.
    Gordley, Larry
    G & A Technical Software.
    Picard, Richard
    Air Force Research Laboratory, Hanscom Air Force Base, Massachusetts.
    Winick, Jeremy
    Air Force Research Laboratory, Hanscom Air Force Base, Massachusetts.
    Wintersteiner, Peter
    ARCON Corporation.
    Paxton, Larry
    Johns Hopkins University Applied Physics Laboratory, Laurel.
    The natural thermostat of nitric oxide emission at 5.3 μm in the thermosphere observed during the solar storms of April 20022003In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 30, no 21Article in journal (Refereed)
    Abstract [en]

    The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment on the Thermosphere-Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite observed the infrared radiative response of the thermosphere to the solar storm events of April 2002. Large radiance enhancements were observed at 5.3 μm, which are due to emission from the vibration-rotation bands of nitric oxide (NO). The emission by NO is indicative of the conversion of solar energy to infrared radiation within the atmosphere and represents a "natural thermostat" by which heat and energy are efficiently lost from the thermosphere to space and to the lower atmosphere. We describe the SABER observations at 5.3 μm and their interpretation in terms of energy loss. The infrared enhancements remain only for a few days, indicating that such perturbations to the thermospheric state, while dramatic, are short-lived. Copyright 2003 by the American Geophysical Union.

  • 24.
    Poppe, A.R.
    et al.
    Space Science Laboratory, University of California, Berkeley.
    Fatemi, Shahab
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Halekas, J.S.
    Space Science Laboratory, University of California, Berkeley.
    Holmström, Mats
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Delory, G.T.
    Space Science Laboratory, University of California, Berkeley.
    ARTEMIS observations of extreme diamagnetic fields in the lunar wake2014In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 41, no 11, p. 3766-3773Article in journal (Refereed)
    Abstract [en]

    We present two Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun ( ARTEMIS) observations of diamagnetic fields in the lunar wake at strengths exceeding twice the ambient magnetic field during high plasma beta conditions. The first observation was 350 km from the lunar surface while the Moon was located in the terrestrial magnetosheath with elevated particle temperatures. The second observation was in the solar wind ranging from 500 to 2000 km downstream, with a relatively low magnetic field strength of approximately 1.6 nT. In both cases, the plasma beta exceeded 10. We discuss the observations and compare the data to hybrid plasma simulations in order to validate the model under such extreme conditions and to elucidate the global structure of the lunar wake during these observations. The extreme nature of the diamagnetic field in the lunar wake provides an important end-member test case for theoretical and modeling studies of the various plasma processes operating in the lunar wake.

  • 25.
    Ramstad, Robin
    et al.
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Futaana, Yoshifumi
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Barabash, Stas
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Nilsson, Hans
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Martin del Campo B, Sergio
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Lundin, Rickard
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Schwingenschuh, Konrad
    Space Research Institute, Austrian Academy of Sciences.
    Phobos 2/ASPERA data revisited: Planetary ion escape rate from Mars near the 1989 solar maximum2013In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 3, p. 477-481Article in journal (Refereed)
    Abstract [en]

    1] Insights about the near-Mars space environment from Mars Express observations have motivated a revisit of the Phobos 2/ASPERA ion data from 1989. We have expanded the analysis to now include all usable heavy ion (O+, O, CO) measurements from the circular orbits of Phobos 2. Phobos 2/ASPERA ion fluxes in the Martian tail are compared with previous results obtained by the instruments on Phobos 2. Further validation of the measurement results is obtained by comparing IMP-8 and Phobos 2/ASPERA solar wind ion fluxes, taking into account the time lag between Earth and Mars. Heavy ion flux measurements from 18 circular equatorial orbits around Mars are bin-averaged to a grid, using the MSE (electric field) frame of reference. The binned data are subsequently integrated to determine the total escape rate of planetary ions. From this we derive a total planetary heavy ion escape rate of (2–3) × 1025 s−1 from Mars for the 1989 solar maximum

  • 26.
    Salvado, Joan A.
    et al.
    Department of Environmental Science and Analytical Chemistry, ACES, Stockholm University.
    Tesi, Tommaso
    Department of Environmental Science and Analytical Chemistry, ACES, Stockholm University.
    Andersson, August
    Department of Environmental Science and Analytical Chemistry, ACES, Stockholm University.
    Ingri, Johan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Dudarev, Oleg
    Pacific Oceanological Institute, Russian Academy of Science, Vladivostok, The National Research Tomsk Polytechnic University.
    Semiletov, Igor
    International Arctic Research Center, University of Alaska Fairbanks, University of Alaska, The National Research Tomsk Polytechnic University.
    Gustafsson, Örjan
    Swedish Museum of Natural History, Institute of Applied Environmental Research (ITM), Stockholm University, Department of Environmental Science and Analytical Chemistry, ACES, Stockholm University.
    Organic carbon remobilized from thawing permafrost is resequestered by reactive iron on the Eurasian Arctic Shelf2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 19, p. 8122-8130Article in journal (Refereed)
    Abstract [en]

    Given the potential for permafrost carbon (PF/C)-climate feedbacks in the Siberian-Arctic land-ocean system, there is a need for understanding the fate of thawed-out PF/C. Here we show that the sequestration of OC by reactive iron (OC-Fe) ranges between 0.5 and 22% on the Eurasian Arctic Shelf, with higher values in the Kara Sea (KS) (186%) and the Laptev Sea (LS) (144%). The C-14/C-13 signatures of the OC-Fe are substantially older and more terrestrial than the bulk sediment OC in the LS but younger and more dominated by marine plankton sources in the East Siberian Sea (ESS). Statistical source apportionment modeling reveal that reactive iron phases resequestered 155% of thawing PF/C in the LS and 6.45% in the ESS, derived from both coastal erosion of ice complex deposit and thawing topsoil. This Fe-associated trap of PF/C constitutes a reduction of the degradation/outgassing and thus also an attenuation of the PF/C-climate feedback

  • 27.
    Siskind, David E.
    et al.
    Space Science Division, Naval Research Laboratory, Washington, DC.
    Marsh, Daniel R.
    National Center for Atmospheric Research, Boulder, Colorado.
    Mlynczak, Martin G.
    NASA Langley Research Center, Hampton.
    Martin-Torres, Javier
    AS&M Inc., Hampton.
    Russell, James M.
    Center for Atmospheric Sciences, Hampton University.
    Decreases in atomic hydrogen over the summer pole: Evidence for dehydration from polar mesospheric clouds?2008In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 35, no 13, article id L13809Article in journal (Refereed)
    Abstract [en]

    Observations from the Sounding of the Atmosphere with Broadband Emission Radiometry (SABER) instrument on the NASA/Thermospheric Ionosphere Mesosphere Energetics and Dynamics satellite show a surprising decrease in the inferred atomic hydrogen (H) over the polar regions in the lowermost thermosphere during the summer. This contrasts with predictions by global models that H should peak in this region at this time. We suggest the decrease is a consequence of the sequestering of the water vapor by the formation of polar mesospheric clouds (PMCs) that redistributes the H2O thus reducing the chemical source of H. This decrease is more pronounced in the Northern rather than the Southern summer which is roughly consistent with the known morphology of PMCs. A model calculation which includes a PMC parameterization gives good qualitative agreement with the data suggesting that this process should be considered in global models of the coupling between the middle and upper atmosphere. Copyright 2008 by the American Geophysical Union.

  • 28.
    Slapak, Rikard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Gunell, H.
    Belgian Institute for Space Aeronomy, Avenue Circulaire, Brussels.
    Hamrin, Maria
    Department of Physics, Umeå University.
    Observations of multiharmonic ion-cyclotron waves due to inverse ion-cyclotron damping in the northern magnetospheric cusp2017In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, no 1, p. 22-29Article in journal (Refereed)
    Abstract [en]

    We present a case study of inverse ion-cyclotron damping taking place in the northern terrestrial magnetospheric cusp, exciting waves at the ion-cyclotron frequency and its harmonics. The ion-cyclotron waves are primarily seen as peaks in the magnetic-field spectral densities. The corresponding peaks in the electric-field spectral densities are not as profound, suggesting a background electric field noise or other processes of wave generation causing the electric spectral densities to smoothen out more compared to the magnetic counterpart. The required condition for inverse ion-cyclotron damping is a velocity shear in the magnetic field-aligned ion-bulk flow, and this condition is often naturally met for magnetosheath influx in the northern magnetospheric cusp, just as in the presented case. We note that some ion-cyclotron wave activity is present in a few similar shear events in the southern cusp, which indicates that other mechanisms generating ion-cyclotron waves may also be present during such conditions.

  • 29. Stebel, K.
    et al.
    Barabash, Victoria
    Kirkwood, S.
    Siebert, J.
    Polar mesosphere summer echoes and noctilucent clouds: Simultaneous and common‐volume observations by radar, lidar and CCD camera2000In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 27, no 5, p. 661-664Article in journal (Refereed)
  • 30.
    Xavier, Prince K.
    et al.
    Met Office Hadley Centre, Exeter.
    John, Viju O.
    Met Office Hadley Centre, Exeter.
    Buehler, Stefan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Ajayamohan, R.S.
    Canadian Centre for Climate Modelling and Analysis, University of Victoria.
    Sijikumar, S.
    Space Physics Laboratory, Trivandrum.
    Variability of Indian summer monsoon in a new upper tropospheric humidity data set2010In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 37, no 5, p. L05705-Article in journal (Refereed)
    Abstract [en]

    Using a new data set we demonstrate the variability of upper troposphere humidity (UTH) associated with the Indian Summer Monsoon (ISM). The main advantage of the new data set is its all-sky representation which is essential to capture the full variability of humidity even in cloudy areas. We show that UTH undergoes significant variations during the active/break phases of the monsoon and discuss the mechanisms. The interannual variations of monsoon are also well reflected in the UTH. A preliminary investigation into the cause of the 2009 monsoon failure reveals anomalous subsidence and suppressed convection over the monsoon region due to anomalous warm conditions in the equatorial Pacific throughout the summer. The large scale drying of the upper troposphere may also have contributed to a negative feedback in suppressing convection. Citation: Xavier, P. K., V. O. John, S. A. Buehler, R. S. Ajayamohan, and S. Sijikumar (2010), Variability of Indian summer monsoon in a new upper tropospheric humidity data set

  • 31.
    Zorzano, María Paz
    et al.
    Centro de Astrobiología Torrejón de Ardoz .
    Mateo-Marti, Eva
    Centro de Astrobiología Torrejón de Ardoz .
    Prieto‐Ballesteros, Olga
    Centro de Astrobiología Torrejón de Ardoz .
    Osuna, S.
    Centro de Astrobiología Torrejón de Ardoz .
    Rennó, Nilton O.
    University of Michigan, Ann Arbor, MI.
    Stability of liquid saline water on present day Mars2009In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 36, no 20, article id L20201Article in journal (Refereed)
    Abstract [en]

    Perchlorate salts (mostly magnesium and sodium perchlorate) have been detected on Mars' arctic soil by the Phoenix lander, furthermore chloride salts have been found on the Meridiani and Gusev sites and on widespread deposits on the southern Martian hemisphere. The presence of these salts on the surface is not only relevant because of their ability to lower the freezing point of water, but also because they can absorb water vapor and form a liquid solution (deliquesce). We show experimentally that small amounts of sodium perchlorate (∼ 1 mg), at Mars atmospheric conditions, spontaneously absorb moisture and melt into a liquid solution growing into ∼ 1 mm liquid spheroids at temperatures as low as 225 K. Also mixtures of water ice and sodium perchlorate melt into a liquid at this temperature. Our results indicate that salty environments make liquid water to be locally and sporadically stable on present day Mars.

1 - 31 of 31
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