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  • Journal article
    Alconcel LNS, Fox P, Brown P, Oddy TM, Lucek EL, Carr CMet al., 2014,

    , GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS, Vol: 3, Pages: 95-109, ISSN: 2193-0856
  • Journal article
    Ruffoni MP, Den Hartog EA, Lawler JE, Brewer NR, Lind K, Nave G, Pickering JCet al., 2014,

    , Monthly Notices of the Royal Astronomical Society, Vol: 441, Pages: 3127-3136, ISSN: 0035-8711

    The Gaia-ESO Public Spectroscopic Survey (GES) is conducting a large-scale study of multi-element chemical abundances of some 100 000 stars in the Milky Way with the ultimate aim of quantifying the formation history and evolution of young, mature and ancient Galactic populations. However, in preparing for the analysis of GES spectra, it has been noted that atomic oscillator strengths of important Fe I lines required to correctly model stellar line intensities are missing from the atomic data base. Here, we present new experimental oscillator strengths derived from branching fractions and level lifetimes, for 142 transitions of Fe I between 3526 and 10 864 Å, of which at least 38 are urgently needed by GES. We also assess the impact of these new data on solar spectral synthesis and demonstrate that for 36 lines that appear unblended in the Sun, Fe abundance measurements yield a small line-by-line scatter (0.08 dex) with a mean abundance of 7.44 dex in good agreement with recent publications.
  • Journal article
    Masters A, 2014,

    , Journal of Geophysical Research: Space Physics, Vol: 119, Pages: 5520-5538, ISSN: 2169-9380

    The magnetosphere of Uranus has barely been explored by spacecraft but is distinct from other solar system magnetospheres in many respects. Determining how this magnetosphere is coupled to the solar wind is central to understanding energy flow through the system. Here we assess how the solar wind interacts with the Uranian magnetosphere via magnetic reconnection. Analytical models of conditions at the magnetopause are combined with current understanding of reconnection onset to predict where reconnection may occur on the boundary. The results suggest that conditions at Uranus' magnetopause are generally less favorable for reconnection than those at the magnetopause of any planet closer to the Sun, as a result of how typical solar wind parameters vary with heliocentric distance. The location of reconnection sites on the Uranian magnetopause is likely to be highly dependent on not only the interplanetary magnetic field orientation but also planetary longitude and season. Solar wind–magnetosphere coupling via magnetic reconnection may be stronger under near鈥恠olstice conditions than under near鈥恊quinox conditions. We discuss the typical reconnection electric field strength at Uranus' magnetopause and suggest that the typical reconnection voltage is considerably less than 40 kV. Complimentary assessments of other means of coupling to the solar wind (e.g., via a “viscous鈥恖ike” interaction) are needed to establish the overall nature of solar wind–magnetosphere coupling at Uranus.
  • Journal article
    Sulaiman AH, Masters A, Dougherty MK, Jia Xet al., 2014,

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 5651-5661, ISSN: 2169-9380
    • Cite
    • Citations: 21
  • Journal article
    McAndrews HJ, Thomsen MF, Arridge CS, Jackman CM, Wilson RJ, Henderson MG, Tokar RL, Khurana KK, Sittler EC, Coates AJ, Dougherty MKet al., 2014,

    , PLANETARY AND SPACE SCIENCE, Vol: 97, Pages: 86-87, ISSN: 0032-0633
  • Journal article
    Jackman CM, Slavin JA, Kivelson MG, Southwood DJ, Achilleos N, Thomsen MF, DiBraccio GA, Eastwood JP, Freeman MP, Dougherty MK, Vogt MFet al., 2014,

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 5465-5494, ISSN: 2169-9380
    • Cite
    • Citations: 67
  • Journal article
    Selzer LA, Hnat B, Osman KT, Nakariakov VM, Eastwood JP, Burgess Det al., 2014,

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 788, ISSN: 2041-8205
  • Journal article
    Owens MJ, Horbury TS, Wicks RT, McGregor SL, Savani NP, Xiong Met al., 2014,

    , Space Weather, Vol: 12, Pages: 395-405, ISSN: 1539-4956

    Advanced forecasting of space weather requires simulation of the whole Sun-to-Earth system, which necessitates driving magnetospheric models with the outputs from solar wind models. This presents a fundamental difficulty, as the magnetosphere is sensitive to both large-scale solar wind structures, which can be captured by solar wind models, and small-scale solar wind “noise,” which is far below typical solar wind model resolution and results primarily from stochastic processes. Following similar approaches in terrestrial climate modeling, we propose statistical “downscaling” of solar wind model results prior to their use as input to a magnetospheric model. As magnetospheric response can be highly nonlinear, this is preferable to downscaling the results of magnetospheric modeling. To demonstrate the benefit of this approach, we first approximate solar wind model output by smoothing solar wind observations with an 8 h filter, then add small-scale structure back in through the addition of random noise with the observed spectral characteristics. Here we use a very simple parameterization of noise based upon the observed probability distribution functions of solar wind parameters, but more sophisticated methods will be developed in the future. An ensemble of results from the simple downscaling scheme are tested using a model-independent method and shown to add value to the magnetospheric forecast, both improving the best estimate and quantifying the uncertainty. We suggest a number of features desirable in an operational solar wind downscaling scheme.
  • Journal article
    Hietala H, Eastwood JP, Isavnin A, 2014,

    , PLASMA PHYSICS AND CONTROLLED FUSION, Vol: 56, ISSN: 0741-3335
    • Cite
    • Citations: 17
  • Journal article
    Miller RL, Schmidt GA, Nazarenko LS, Tausnev N, Bauer SE, DelGenio AD, Kelley M, Lo KK, Ruedy R, Shindell DT, Aleinov I, Bauer M, Bleck R, Canuto V, Chen Y, Cheng Y, Clune TL, Faluvegi G, Hansen JE, Healy RJ, Kiang NY, Koch D, Lacis AA, LeGrande AN, Lerner J, Menon S, Oinas V, Garcia-Pando CP, Perlwitz JP, Puma MJ, Rind D, Romanou A, Russell GL, Sato M, Sun S, Tsigaridis K, Unger N, Voulgarakis A, Yao M-S, Zhang Jet al., 2014,

    , JOURNAL OF ADVANCES IN MODELING EARTH SYSTEMS, Vol: 6, Pages: 441-477
    • Cite
    • Citations: 136
  • Journal article
    Marlier ME, Voulgarakis A, Shindell DT, Faluvegi G, Henry CL, Randerson JTet al., 2014,

    , ATMOSPHERIC ENVIRONMENT, Vol: 89, Pages: 158-168, ISSN: 1352-2310
    • Cite
    • Citations: 12
  • Journal article
    Gryspeerdt E, Stier P, Grandey BS, 2014,

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 41, Pages: 3622-3627, ISSN: 0094-8276
    • Cite
    • Citations: 44
  • Journal article
    Nichols JD, Badman SV, Baines KH, Brown RH, Bunce EJ, Clarke JT, Cowley SWH, Crary FJ, Dougherty MK, Gerard J-C, Grocott A, Grodent D, Kurth WS, Melin H, Mitchell DG, Pryor WR, Stallard TSet al., 2014,

    , Geophysical Research Letters, Vol: 41, Pages: 3323-3330, ISSN: 1944-8007

    We present observations of significant dynamics within two UV auroral storms observedon Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroralemission observed at the poleward boundary of a solar wind-induced auroral storm, propagating at ∼330%rigid corotation from near ∼01 h LT toward ∼08 h LT. We suggest that these are indicative of ongoing, burstyreconnection of lobe flux in the magnetotail, providing strong evidence that Saturn’s auroral storms arecaused by large-scale flux closure. We also discuss the later evolution of a similar storm and show that theemission maps to the trailing region of an energetic neutral atom enhancement. We thus identify the auroralform with the upward field-aligned continuity currents flowing into the associated partial ring current.
  • Journal article
    Simon S, Saur J, van Treeck SC, Kriegel H, Dougherty MKet al., 2014,

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 41, Pages: 3359-3366, ISSN: 0094-8276
    • Cite
    • Citations: 14
  • Journal article
    Ceppi P, Zelinka MD, Hartmann DL, 2014,

    , Geophysical Research Letters, Vol: 41, Pages: 3244-3250, ISSN: 0094-8276

    A strong relationship is found between changes in the meridional gradient of absorbed shortwave radiation (ASR) and Southern Hemispheric jet shifts in 21st century climate simulations of CMIP5 (Coupled Model Intercomparison Project phase 5) coupled models. The relationship is such that models with increases in the meridional ASR gradient around the southern midlatitudes, and therefore increases in midlatitude baroclinicity, tend to produce a larger poleward jet shift. The ASR changes are shown to be dominated by changes in cloud properties, with sea ice declines playing a secondary role. We demonstrate that the ASR changes are the cause, and not the result, of the intermodel differences in jet response by comparing coupled simulations with experiments in which sea surface temperature increases are prescribed. Our results highlight the importance of reducing the uncertainty in cloud feedbacks in order to constrain future circulation changes.
  • Book chapter
    Galand MIF, Coates A, Cravens T, Wahlund J-Eet al., 2014,

    Titan's Ionosphere

    , Titan: Interior, Surface, Atmosphere, and Space Environment, Editors: Mueller-Wodarg, Griffith, Lellouch, Cravens, Publisher: Cambridge University Press, Pages: 376-418, ISBN: 9780521199926
  • Journal article
    Vigren E, Galand M, Shebanits O, Wahlund J-E, Geppert WD, Lavvas P, Vuitton V, Yelle RVet al., 2014,

    , ASTROPHYSICAL JOURNAL, Vol: 786, ISSN: 0004-637X
    • Cite
    • Citations: 10
  • Journal article
    Southwood D, 2014,

    , NATURE, Vol: 509, Pages: 32-32, ISSN: 0028-0836
  • Journal article
    Bunce EJ, Grodent DC, Jinks SL, Andrews DJ, Badman SV, Coates AJ, Cowley SWH, Dougherty MK, Kurth WS, Mitchell DG, Provan Get al., 2014,

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 3528-3543, ISSN: 2169-9380
    • Cite
    • Citations: 17
  • Journal article
    Ansell C, Brindley HE, Pradhan Y, Saunders Ret al., 2014,

    , JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, Vol: 119, Pages: 4070-4086, ISSN: 2169-897X
    • Cite
    • Citations: 15
  • Journal article
    Goldman MV, Newman DL, Lapenta G, Andersson L, Gosling JT, Eriksson S, Markidis S, Eastwood JP, Ergun Ret al., 2014,

    , PHYSICAL REVIEW LETTERS, Vol: 112, ISSN: 0031-9007
    • Cite
    • Citations: 56
  • Journal article
    Badman SV, Branduardi-Raymont G, Galand M, Hess SLG, Krupp N, Lamy L, Melin H, Tao Cet al., 2014,

    , Space Science Reviews, Vol: 187, Pages: 99-179, ISSN: 1572-9672

    The ionospheric response to auroral precipitation at the giant planets is reviewed,using models and observations. The emission processes for aurorae at radio, infrared, visible,ultraviolet, and X-ray wavelengths are described, and exemplified using ground- andspace-based observations. Comparisons between the emissions at different wavelengths are made, where possible, and interpreted in terms of precipitating particle characteristics oratmospheric conditions. Finally, the spatial distributions and dynamics of the various componentsof the aurorae (moon footprints, low-latitude, main oval, polar) are related to magnetosphericprocesses and boundaries, using theory, in situ, and remote observations, withthe aim of distinguishing between those related to internally-driven dynamics, and thoserelated to the solar wind interaction.
  • Journal article
    Messori G, Czaja A, 2014,

    , QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Vol: 140, Pages: 1377-1386, ISSN: 0035-9009
  • Journal article
    Shen C, Yang YY, Rong ZJ, Li X, Dunlop M, Carr CM, Liu ZX, Baker DN, Chen ZQ, Ji Y, Zeng Get al., 2014,

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2458-2465, ISSN: 2169-9380
    • Cite
    • Citations: 36
  • Journal article
    Fuselier SA, Frahm R, Lewis WS, Masters A, Mukherjee J, Petrinec SM, Sillanpaa IJet al., 2014,

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2563-2578, ISSN: 2169-9380
    • Cite
    • Citations: 55
  • Journal article
    Pilkington NM, Achilleos N, Arridge CS, Masters A, Sergis N, Coates AJ, Dougherty MKet al., 2014,

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2858-2875, ISSN: 2169-9380
    • Cite
    • Citations: 20
  • Journal article
    Kriegel H, Simon S, Meier P, Motschmann U, Saur J, Wennmacher A, Strobel DF, Dougherty MKet al., 2014,

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2740-2774, ISSN: 2169-9380
    • Cite
    • Citations: 39
  • Journal article
    Meredith CJ, Alexeev II, Badman SV, Belenkaya ES, Cowley SWH, Dougherty MK, Kalegaev VV, Lewis GR, Nichols JDet al., 2014,

    , 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
    Masters A, Fujimoto M, Hasegawa H, Russell CT, Coates AJ, Dougherty MKet al., 2014,

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 41, Pages: 1862-1868, ISSN: 0094-8276
    • Cite
    • Citations: 23
  • Journal article
    Cargill PJ, 2014,

    , ASTROPHYSICAL JOURNAL, Vol: 784, ISSN: 0004-637X
    • Cite
    • Citations: 73

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