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  • Journal article
    Messori G, Czaja A, 2014,

    Some considerations on the spectral features of meridional heat transport by transient eddies

    , QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Vol: 140, Pages: 1377-1386, ISSN: 0035-9009
  • Journal article
    Masters A, Fujimoto M, Hasegawa H, Russell CT, Coates AJ, Dougherty MKet al., 2014,

    Can magnetopause reconnection drive Saturn's magnetosphere?

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 41, Pages: 1862-1868, ISSN: 0094-8276
  • Journal article
    Meredith CJ, Alexeev II, Badman SV, Belenkaya ES, Cowley SWH, Dougherty MK, Kalegaev VV, Lewis GR, Nichols JDet al., 2014,

    Saturn's dayside ultraviolet auroras: Evidence for morphological dependence on the direction of the upstream interplanetary magnetic field

    , Journal of Geophysical Research: Space Physics, Vol: 119, Pages: 1994-2008, ISSN: 2169-9402

    We examine a unique data set from seven Hubble Space Telescope (HST) “visits” that imagedSaturn’s northern dayside ultraviolet emissions exhibiting usual circumpolar “auroral oval” morphologies,during which Cassini measured the interplanetary magnetic field (IMF) upstream of Saturn’s bow shock overintervals of several hours. The auroras generally consist of a dawn arc extending toward noon centered near~15° colatitude, together with intermittent patchy forms at ~10° colatitude and poleward thereof, locatedbetween noon and dusk. The dawn arc is a persistent feature, but exhibits variations in position, width, andintensity, which have no clear relationship with the concurrent IMF. However, the patchy postnoon aurorasare found to relate to the (suitably lagged and averaged) IMF Bz, being present during all four visits withpositive Bz and absent during all three visits with negative Bz. The most continuous such forms occur in thecase of strongest positive Bz. These results suggest that the postnoon forms are associated with reconnectionand open flux production at Saturn’s magnetopause, related to the similarly interpreted bifurcated auroral arcstructures previously observed in this local time sector in Cassini Ultraviolet Imaging Spectrograph data,whose details remain unresolved in these HST images. One of the intervals with negative IMF Bz howeverexhibits a prenoon patch of very high latitude emission extending poleward of the dawn arc to the magnetic/spin pole, suggestive of the occurrence of lobe reconnection. Overall, these data provide evidence ofsignificant IMF dependence in the morphology of Saturn’s dayside auroras.
  • Journal article
    Cargill PJ, 2014,

    ACTIVE REGION EMISSION MEASURE DISTRIBUTIONS AND IMPLICATIONS FOR NANOFLARE HEATING

    , ASTROPHYSICAL JOURNAL, Vol: 784, ISSN: 0004-637X
  • Journal article
    Jasinski JM, Arridge CS, Lamy L, Leisner JS, Thomsen MF, Mitchell DG, Coates AJ, Radioti A, Jones GH, Roussos E, Krupp N, Grodent D, Dougherty MK, Waite JHet al., 2014,

    Cusp observation at Saturn's high-latitude magnetosphere by the Cassini spacecraft

    , Geophysical Research Letters, Vol: 41, Pages: 1382-1388, ISSN: 1944-8007

    We report on the first analysis of magnetospheric cusp observations at Saturn by multiple insitu instruments onboard the Cassini spacecraft. Using this we infer the process of reconnection wasoccurring at Saturn’s magnetopause. This agrees with remote observations that showed the associatedauroral signatures of reconnection. Cassini crossed the northern cusp around noon local time along apoleward trajectory. The spacecraft observed ion energy-latitude dispersions—a characteristic signature ofthe terrestrial cusp. This ion dispersion is “stepped,” which shows that the reconnection is pulsed. The ionenergy-pitch angle dispersions suggest that the field-aligned distance from the cusp to the reconnectionsite varies between ∼27 and 51 RS. An intensification of lower frequencies of the Saturn kilometricradiation emissions suggests the prior arrival of a solar wind shock front, compressing the magnetosphereand providing more favorable conditions for magnetopause reconnection.
  • Journal article
    Hartmann DL, Ceppi P, 2014,

    Trends in the CERES dataset, 2000-13: the effects of sea ice and jet shifts and comparison to climate models

    , Journal of Climate, Vol: 27, Pages: 2444-2456, ISSN: 0894-8755

    The Clouds and the Earth’s Radiant Energy System (CERES) observations of global top-of-atmosphere radiative energy fluxes for the period March 2000–February 2013 are examined for robust trends and variability. The trend in Arctic ice is clearly evident in the time series of reflected shortwave radiation, which closely follows the record of ice extent. The data indicate that, for every 106 km2 decrease in September sea ice extent, annual-mean absorbed solar radiation averaged over 75°–90°N increases by 2.5 W m−2, or about 6 W m−2 between 2000 and 2012. CMIP5 models generally show a much smaller change in sea ice extent over the 1970–2012 period, but the relationship of sea ice extent to reflected shortwave is in good agreement with recent observations. Another robust trend during this period is an increase in reflected shortwave radiation in the zonal belt from 45° to 65°S. This trend is mostly related to increases in sea ice concentrations in the Southern Ocean and less directly related to cloudiness trends associated with the annular variability of the Southern Hemisphere. Models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) produce a scaling of cloud reflection to zonal wind increase that is similar to trend observations in regions separated from the direct effects of sea ice. Atmospheric Model Intercomparison Project (AMIP) model responses over the Southern Ocean are not consistent with each other or with the observed shortwave trends in regions removed from the direct effect of sea ice.
  • Journal article
    Southwood DJ, Cowley SWH, 2014,

    The origin of Saturn's magnetic periodicities: Northern and southern current systems

    , Journal of Geophysical Research: Space Physics, Vol: 119, Pages: 1563-1571, ISSN: 2169-9380

    The recent survey by Andrews et al. (2012) of the separate northern and southern ~10.7 h periodic magnetic signals in Saturn's magnetosphere limits very much their governing current systems. The existence of signals with pure or close to pure northern or southern periods in respective polar caps taken with the relatively narrow bandwidth of the signals indicates that the actual periodicities are imposed independently from northern and southern polar regions, i.e., the open field line regions. Field‐aligned currents must flow on the boundaries of these regions to exclude signals from the other hemisphere. Equatorward of the polar cap, on closed magnetic shells, there are distinct north and south “cam” source currents, the distinction being made clear by a difference in polarization. We outline the consequences for the governing current systems and the implications for sustaining the energy and power dissipation in the system.
  • Journal article
    Simon S, Neubauer FM, Wennmacher A, Dougherty MKet al., 2014,

    Variability of Titan's induced magnetotail: Cassini magnetometer observations

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2024-2037, ISSN: 2169-9380
  • Journal article
    Mistry R, Dougherty MK, Masters A, Sulaiman AH, Allen EJet al., 2014,

    Separating drivers of Saturnian magnetopause motion

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 1514-1522, ISSN: 2169-9380
  • Journal article
    Schmidt GA, Kelley M, Nazarenko L, Ruedy R, Russell GL, Aleinov I, Bauer M, Bauer SE, Bhat MK, Bleck R, Canuto V, Chen Y-H, Cheng Y, Clune TL, Del Genio A, de Fainchtein R, Faluvegi G, Hansen JE, Healy RJ, Kiang NY, Koch D, Lacis AA, LeGrande AN, Lerner J, Lo KK, Matthews EE, Menon S, Miller RL, Oinas V, Oloso AO, Perlwitz JP, Puma MJ, Putman WM, Rind D, Romanou A, Sato M, Shindell DT, Sun S, Syed RA, Tausnev N, Tsigaridis K, Unger N, Voulgarakis A, Yao M-S, Zhang Jet al., 2014,

    Configuration and assessment of the GISS ModelE2 contributions to the CMIP5 archive

    , JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS, Vol: 6, Pages: 141-184
  • Journal article
    Schwartz SJ, 2014,

    Comment on "Electron demagnetization and heating in quasi-perpendicular shocks" by Mozer and Sundkvist

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 1507-1512, ISSN: 2169-9380
  • Journal article
    Liu YD, Luhmann JG, Kajdic P, Kilpua EKJ, Lugaz N, Nitta NV, Moestl C, Lavraud B, Bale SD, Farrugia CJ, Galvin ABet al., 2014,

    Observations of an extreme storm in interplanetary space caused by successive coronal mass ejections

    , NATURE COMMUNICATIONS, Vol: 5, ISSN: 2041-1723
  • Journal article
    Cui J, Yelle RV, Li T, Snowden DS, Mueller-Wodarg ICFet al., 2014,

    Density waves in Titan's upper atmosphere

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 490-518, ISSN: 2169-9380
  • Book chapter
    Mueller-Wodarg ICF, 2014,

    Titan's upper atmosphere: thermal structure, dynamics, and energetics

    , Titan: Interior, Surface, Atmosphere, and Space Environment, Editors: Müller-Wodarg, Griffith, Lellouch, Cravens, Publisher: Cambridge University Press, ISBN: 9780521199926

    Titan, the largest of Saturn's moons, shares remarkable similarities with Earth. Its thick atmosphere is composed primarily of nitrogen; it features the most complex organic chemistry known outside of Earth and, uniquely, hosts an analog to Earth's hydrological cycle, with methane forming clouds, rain and seas. Using the latest data from the ongoing Cassini–Huygens missions, laboratory measurements and numerical simulations, this comprehensive reference examines the physical processes that shape Titan's fascinating atmospheric structure and chemistry, weather, climate, circulation and surface geology. The text also surveys leading theories about Titan's origin and evolution, and assesses their implications for understanding the formation of other complex planetary bodies. Written by an international team of specialists, chapters offer detailed, comparative treatments of Titan's known properties and discuss the latest frontiers in the Cassini–Huygens mission, offering students and researchers of planetary science, geology, astronomy and space physics an insightful reference and guide.
  • Journal article
    Wicks RT, Roberts DA, Mallet A, Schekochihin AA, Horbury TS, Chen CHKet al., 2014,

    CORRELATIONS AT LARGE SCALES AND THE ONSET OF TURBULENCE IN THE FAST SOLAR WIND (vol 778, pg 177, 2013)

    , ASTROPHYSICAL JOURNAL, Vol: 782, ISSN: 0004-637X
  • Journal article
    Gryspeerdt E, Stier P, Partridge DG, 2014,

    Satellite observations of cloud regime development: the role of aerosol processes

    , Atmospheric Chemistry and Physics, Vol: 14, Pages: 1141-1158, ISSN: 1680-7324
  • Journal article
    Weiss Z, Steers EBM, Pickering JC, Mushtaq Set al., 2014,

    Transition rate diagrams - A new approach to the study of selective excitation processes: The spectrum of manganese in a Grimm-type glow discharge

    , SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY, Vol: 92, Pages: 70-83, ISSN: 0584-8547
  • Journal article
    Southwood D, 2014,

    Saturn's mysterious magnetism

    , ASTRONOMY & GEOPHYSICS, Vol: 55, Pages: 13-18, ISSN: 1366-8781
  • Journal article
    Pulupa MP, Bale SD, Salem C, Horaites Ket al., 2014,

    Journal of Geophysical Research: Space Physics

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 647-657, ISSN: 2169-9380
  • Journal article
    Andriopoulou M, Roussos E, Krupp N, Paranicas C, Thomsen M, Krimigis S, Dougherty MK, Glassmeier K-Het al., 2014,

    Spatial and temporal dependence of the convective electric field in Saturn's inner magnetosphere

    , ICARUS, Vol: 229, Pages: 57-70, ISSN: 0019-1035
  • Journal article
    Mitchell JJ, Schwartz SJ, 2014,

    Isothermalmagnetosheath electrons due to nonlocal electron cross talk

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 1080-1093, ISSN: 2169-9380
  • Journal article
    Chakravorty S, Chowdary JS, Gnanaseelan C, 2014,

    Epochal changes in the seasonal evolution of tropical Indian Ocean warming associated with El Niño

    , Climate Dynamics, Vol: 42, Pages: 805-822, ISSN: 0930-7575
  • Journal article
    Collinson GA, Sibeck DG, Masters A, Shane N, Zhang TL, Fedorov A, Barabash S, Coates AJ, Moore TE, Slavin JA, Uritsky VM, Boardsen S, Sarantos Met al., 2014,

    A survey of hot flow anomalies at Venus

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 978-991, ISSN: 2169-9380
  • Journal article
    Chaston CC, Bonnell JW, Wygant JR, Mozer F, Bale SD, Kersten K, Breneman AW, Kletzing CA, Kurth WS, Hospodarsky GB, Smith CW, MacDonald EAet al., 2014,

    Observations of kinetic scale field line resonances

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 41, Pages: 209-215, ISSN: 0094-8276
  • Journal article
    Matteini L, Horbury TS, Neugebauer M, Goldstein BEet al., 2014,

    Dependence of solar wind speed on the local magnetic field orientation: Role of Alfvenic fluctuations

    , Geophysical Research Letters, Vol: 41, Pages: 259-265, ISSN: 0094-8276

    We report an analysis of correlations between magnetic field and velocity fluctuations in the fast solar wind beyond 1 AU at high latitudes. We have found that on scales shorter than the microstream structures, there exists a well‐defined dependence of the flow speed on the angle between the magnetic field vector and the radial direction. Solar wind is found to be slightly faster when the measured magnetic field vector is transverse to the velocity, while it is always slower when the magnetic field is parallel, or antiparallel, to the radial direction. We show that this correlation is a direct consequence of the high Alfvénicity of fast wind fluctuations and that it can be reasonably described by a simple model taking into account the main properties of the low‐frequency antisunward Alfvén fluctuations as observed in the solar wind plasma. We also discuss how switchbacks, short periods of magnetic field reversals, naturally fit in this new observed correlation.
  • Journal article
    Erdos G, Balogh A, 2014,

    MAGNETIC FLUX DENSITY IN THE HELIOSPHERE THROUGH SEVERAL SOLAR CYCLES

    , ASTROPHYSICAL JOURNAL, Vol: 781, ISSN: 0004-637X
  • Journal article
    Matta M, Galand M, Moore L, Mendillo M, Withers Pet al., 2014,

    Numerical simulations of ion and electron temperatures in the ionosphere of Mars: Multiple ions and diurnal variations

    , ICARUS, Vol: 227, Pages: 78-88, ISSN: 0019-1035
  • Conference paper
    Daykin-Iliopoulos A, Desai R, 2014,

    Performance evaluation of micropropulsion systems with the application of Active Debris Removal

    Recent micropropulsion developments have increased the operational capabilities of microsatellites (< 100 kg), to the point where they are being considered for demanding missions such as Active Debris Removal (ADR). This study examines the state-of-the-art micropropulsion options that can be applied to a microsatellite performing a range of orbital manoeuvres such as ADR. To this end a generic system architecture is used for this example scenario with ranging delta-v requirements. A variety of propulsion systems are sized accordingly, and the trade-offs between the differing propulsion technologies evaluated with respect to the power requirements, System-Specific Impulse , and technology readiness level (TRL), as well as a ‘newly defined’ volume driven System-Specific Impulse . It was shown that the high specific impulse (> 2000s) and consequent mass and volume savings of miniaturised Electric Propulsion (EP) systems, such as the miniature ion and colloid thrusters, results in optimal ISSP’s and ISSP’s for the ADR scenario examined. Moreover an in-depth combined quantitative and qualitative analysis identifies delta-v regions most suited to both EP and Chemical Propulsion (CP) systems, as well as highlighting the inherent differences in the varying technologies with respect to volume as well as mass.
  • Journal article
    Alconcel LNS, Fox P, Brown P, Oddy TM, Lucek EL, Carr CMet al., 2014,

    An initial investigation of the long-term trends in the fluxgate magnetometer (FGM) calibration parameters on the four Cluster spacecraft

    , GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS, Vol: 4, Pages: 43-84, ISSN: 2193-0856
  • Journal article
    Sheldon L, Czaja A, 2014,

    Seasonal and interannual variability of an index of deep atmospheric convection over western boundary currents

    , QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Vol: 140, Pages: 22-30, ISSN: 0035-9009

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