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  • Journal article
    Voulgarakis A, Shindell DT, Faluvegi G, 2013,

    Linkages between ozone-depleting substances, tropospheric oxidation and aerosols

    , Atmospheric Chemistry and Physics, Vol: 13, Pages: 4907-4916

    <jats:p>Abstract. Coupling between the stratosphere and the troposphere allows changes in stratospheric ozone abundances to affect tropospheric chemistry. Large-scale effects from such changes on chemically produced tropospheric aerosols have not been systematically examined in past studies. We use a composition-climate model to investigate potential past and future impacts of changes in stratospheric ozone depleting substances (ODS) on tropospheric oxidants and sulfate aerosols. In most experiments, we find significant responses in tropospheric photolysis and oxidants, with small but significant effects on methane radiative forcing. The response of sulfate aerosols is sizeable when examining the effect of increasing future nitrous oxide (N2O) emissions. We also find that without the regulation of chlorofluorocarbons (CFCs) through the Montreal Protocol, sulfate aerosols could have increased by 2050 by a comparable amount to the decreases predicted due to relatively stringent sulfur emissions controls. The individual historical radiative forcings of CFCs and N2O through their indirect effects on methane (−22.6 mW m−2 for CFCs and −6.7 mW m−2 for N2O) and sulfate aerosols (−3.0 mW m−2 for CFCs and +6.5 mW m−2 for N2O when considering the direct aerosol effect) discussed here are non-negligible when compared to known historical ODS forcing. Our results stress the importance of accounting for stratosphere-troposphere, gas-aerosol and composition-climate interactions when investigating the effects of changing emissions on atmospheric composition and climate. </jats:p>
  • Journal article
    Dhomse SS, Chipperfield MP, Feng W, Ball WT, Unruh YC, Haigh JD, Krivova NA, Solanki SK, Smith AKet al., 2013,

    Stratospheric O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; changes during 2001–2010: the small role of solar flux variations in a CTM

    <jats:p>Abstract. Solar spectral fluxes (or irradiance) measured by the SOlar Radiation and Climate Experiment (SORCE) show different variability at ultraviolet (UV) wavelengths compared to other irradiance measurements and models (e.g. NRL-SSI, SATIRE-S). Some modelling studies have suggested that stratospheric/lower mesospheric O3 changes during solar cycle 23 (1996–2008) can only be reproduced if SORCE solar fluxes are used. We have used a 3-D chemical transport model (CTM), forced by meteorology from the European Centre for Medium-Range Weather Forecasts (ECMWF), to simulate middle atmospheric O3 using three different solar flux datasets (SORCE, NRL-SSI and SATIRE-S). Simulated O3 changes are compared with Microwave Limb Sounder (MLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) satellite data. Modelled O3 anomalies from all solar flux datasets show good agreement with the observations, despite the different flux variations. The off-line CTM reproduces these changes through dynamical information contained in the analyses. A notable feature during this period is a robust positive solar signal in the tropical middle stratosphere due to changes in stratospheric dynamics. Ozone changes in the lower mesosphere cannot be used to discriminate between solar flux datasets due to large uncertainties and the short time span of the observations. Overall this study suggests that, in a CTM, the UV variations detected by SORCE are not necessary to reproduce observed stratospheric O3 changes during 2001–2010. </jats:p>
  • Journal article
    Ceppi P, Hartmann DL, 2013,

    On the speed of the eddy-driven jet and the width of the hadley cell in the Southern Hemisphere

    , Journal of Climate, Vol: 26, Pages: 3450-3465, ISSN: 0894-8755

    A strong correlation between the speed of the eddy-driven jet and the width of the Hadley cell is found to exist in the Southern Hemisphere, both in reanalysis data and in twenty-first-century integrations from the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report multimodel archive. Analysis of the space–time spectra of eddy momentum flux reveals that variations in eddy-driven jet speed are related to changes in the mean phase speed of midlatitude eddies. An increase in eddy phase speeds induces a poleward shift of the critical latitudes and a poleward expansion of the region of subtropical wave breaking. The associated changes in eddy momentum flux convergence are balanced by anomalous meridional winds consistent with a wider Hadley cell. At the same time, faster eddies are also associated with a strengthened poleward eddy momentum flux, sustaining a stronger westerly jet in midlatitudes. The proposed mechanism is consistent with the seasonal dependence of the interannual variability of the Hadley cell width and appears to explain at least part of the projected twenty-first-century trends.
  • Journal article
    Branduardi-Raymont G, Ford PG, Hansen KC, Lamy L, Masters A, Cecconi B, Coates AJ, Dougherty MK, Gladstone GR, Zarka Pet al., 2013,

    Search for Saturn's X-ray aurorae at the arrival of a solar wind shock

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 2145-2156, ISSN: 2169-9380
  • Journal article
    Andres N, Gomez DO, Bertucci C, Mazelle C, Dougherty MKet al., 2013,

    Saturn's ULF wave foreshock boundary: Cassini observations

    , PLANETARY AND SPACE SCIENCE, Vol: 79-80, Pages: 64-75, ISSN: 0032-0633
  • Journal article
    Zhong J, Pu ZY, Dunlop MW, Bogdanova YV, Wang XG, Xiao CJ, Guo RL, Hasegawa H, Raeder J, Zhou XZ, Angelopoulos V, Zong QG, Fu SY, Xie L, Taylor MGGT, Shen C, Berchem J, Zhang QH, Volwerk M, Eastwood JPet al., 2013,

    Three-dimensional magnetic flux rope structure formed by multiple sequential X-line reconnection at the magnetopause

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 1904-1911, ISSN: 2169-9380
  • Journal article
    Bowman KW, Shindell DT, Worden HM, Lamarque JF, Young PJ, Stevenson DS, Qu Z, de la Torre M, Bergmann D, Cameron-Smith PJ, Collins WJ, Doherty R, Dalsøren SB, Faluvegi G, Folberth G, Horowitz LW, Josse BM, Lee YH, MacKenzie IA, Myhre G, Nagashima T, Naik V, Plummer DA, Rumbold ST, Skeie RB, Strode SA, Sudo K, Szopa S, Voulgarakis A, Zeng G, Kulawik SS, Aghedo AM, Worden JRet al., 2013,

    Evaluation of ACCMIP outgoing longwave radiation from tropospheric ozone using TES satellite observations

    , Atmospheric Chemistry and Physics, Vol: 13, Pages: 4057-4072
  • Journal article
    Zhong W, Haigh JD, 2013,

    The greenhouse effect and carbon dioxide

    , WEATHER, Vol: 68, Pages: 100-105, ISSN: 0043-1656
  • Journal article
    Grasset O, Dougherty MK, Coustenis A, Bunce EJ, Erd C, Titov D, Blanc M, Coates A, Drossart P, Fletcher LN, Hussmann H, Jaumann R, Krupp N, Lebreton J-P, Prieto-Ballesteros O, Tortora P, Tosi F, Van Hoolst Tet al., 2013,

    JUpiter ICy moons Explorer (JUICE): An ESA mission to orbit Ganymede and to characterise the Jupiter system

    , PLANETARY AND SPACE SCIENCE, Vol: 78, Pages: 1-21, ISSN: 0032-0633
  • Journal article
    Messori G, Czaja A, 2013,

    On the sporadic nature of meridional heat transport by transient eddies

    , QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Vol: 139, Pages: 999-1008, ISSN: 0035-9009
  • Journal article
    Simon S, van Treeck SC, Wennmacher A, Saur J, Neubauer FM, Bertucci CL, Dougherty MKet al., 2013,

    Structure of Titan's induced magnetosphere under varying background magnetic field conditions: Survey of Cassini magnetometer data from flybys TA-T85

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 1679-1699, ISSN: 2169-9380
  • Journal article
    Sergis N, Jackman CM, Masters A, Krimigis SM, Thomsen MF, Hamilton DC, Mitchell DG, Dougherty MK, Coates AJet al., 2013,

    Particle and magnetic field properties of the Saturnian magnetosheath: Presence and upstream escape of hot magnetospheric plasma

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 1620-1634, ISSN: 2169-9380
  • Journal article
    Hellinger P, Trávníček PM, Štverák Š, Matteini L, Velli Met al., 2013,

    Proton thermal energetics in the solar wind: Helios reloaded

    , Journal of Geophysical Research: Space Physics, Vol: 118, Pages: 1351-1365, ISSN: 2169-9380

    <jats:p>The proton thermal energetics in the slow solar wind between 0.3 and 1 AU is reinvestigated using the Helios 1 and 2 data, complementing a similar analysis for the fast solar wind [Hellinger et al., 2011]. The results for slow and fast solar winds are compared and discussed in the context of previous results. Protons need to be heated in the perpendicular direction with respect to the ambient magnetic field from 0.3 to 1 AU. In the parallel direction, protons need to be cooled at 0.3 AU, with a cooling rate comparable to the corresponding perpendicular heating rate; between 0.3 and 1 AU, the required cooling rate decreases until a transition to heating occurs: by 1 AU the protons require parallel heating, with a heating rate comparable to that required to sustain the perpendicular temperature. The heating/cooling rates (per unit volume) in the fast and slow solar winds are proportional to the ratio between the proton kinetic energy and the expansion time. On average, the protons need to be heated and the necessary heating rates are comparable to the energy cascade rate of the magnetohydrodynamic turbulence estimated from the stationary Kolmogorov‐Yaglom law at 1 AU; however, in the expanding solar wind, the stationarity assumption for this law is questionable. The turbulent energy cascade may explain the average proton energetics (although the stationarity assumption needs to be justified) but the parallel cooling is likely related to microinstabilities connected with the structure of the proton velocity distribution function. This is supported by linear analysis based on observed data and by results of numerical simulations.</jats:p>
  • Journal article
    Badman SV, Masters A, Hasegawa H, Fujimoto M, Radioti A, Grodent D, Sergis N, Dougherty MK, Coates AJet al., 2013,

    Bursty magnetic reconnection at Saturn's magnetopause

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 40, Pages: 1027-1031, ISSN: 0094-8276
  • Journal article
    Masters A, Stawarz L, Fujimoto M, Schwartz SJ, Sergis N, Thomsen MF, Retino A, Hasegawa H, Zieger B, Lewis GR, Coates AJ, Canu P, Dougherty MKet al., 2013,

    Electron acceleration to relativistic energies at a strong quasi-parallel shock wave

    , NATURE PHYSICS, Vol: 9, Pages: 164-167, ISSN: 1745-2473
  • Journal article
    Coustenis A, Atreya S, Castillo J, Coll P, Mueller-Wodarg I, Spilker Let al., 2013,

    Surfaces, atmospheres and magnetospheres of the outer planets and their satellites and ring systems: Part VIII Preface

    , PLANETARY AND SPACE SCIENCE, Vol: 77, Pages: 1-2, ISSN: 0032-0633
  • Journal article
    Chakravorty S, Chowdary JS, Gnanaseelan C, 2013,

    Spring asymmetric mode in the tropical Indian Ocean: role of El Niño and IOD

    , Climate Dynamics, Vol: 40, Pages: 1467-1481, ISSN: 0930-7575
  • Journal article
    Vigren E, Galand M, Yelle RV, Cui J, Wahlund J-E, Agren K, Lavvas PP, Mueller-Wodarg ICF, Strobel DF, Vuitton V, Bazin Aet al., 2013,

    On the thermal electron balance in Titan's sunlit upper atmosphere

    , ICARUS, Vol: 223, Pages: 234-251, ISSN: 0019-1035
  • Journal article
    Lavvas P, Yelle RV, Koskinen T, Bazin A, Vuitton V, Vigren E, Galand M, Wellbrock A, Coates AJ, Wahlund J-E, Crary FJ, Snowden Det al., 2013,

    Aerosol growth in Titan's ionosphere

    , PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 110, Pages: 2729-2734, ISSN: 0027-8424
  • Journal article
    Matteini L, Landi S, Velli M, Matthaeus WHet al., 2013,

    Proton temperature anisotropy and magnetic reconnection in the solar wind: effects of kinetic instabilities on current sheet stability

    , The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 763, ISSN: 0004-637X

    We investigate the role of kinetic instabilities driven by a proton anisotropy on the onset of magnetic reconnection by means of two-dimensional hybrid simulations. The collisionless tearing of a current sheet is studied in the presence of a proton temperature anisotropy in the surrounding plasma. Our results confirm that anisotropic protons within the current sheet region can significantly enhance/stabilize the tearing instability of the current. Moreover, fluctuations associated with linear instabilities excited by large proton temperature anisotropies can significantly influence the stability of the plasma and perturb the current sheets, triggering the tearing instability. We find that such a complex coupling leads to a faster tearing evolution in the $T_\perp >T_\Vert$ regime when an ion-cyclotron instability is generated by the anisotropic proton distribution functions. On the contrary, in the presence of the opposite anisotropy, fire-hose fluctuations excited by the unstable background protons with $T_\Vert <T_\perp$ are not able to efficiently destabilize current sheets, which remain stable for a long time after fire-hose saturation. We discuss possible influences of this novel coupling on the solar wind and heliospheric plasma dynamics.
  • Journal article
    Shi QQ, Zong Q-G, Fu SY, Dunlop MW, Pu ZY, Parks GK, Wei Y, Li WH, Zhang H, Nowada M, Wang YB, Sun WJ, Xiao T, Reme H, Carr C, Fazakerley AN, Lucek Eet al., 2013,

    Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times

    , NATURE COMMUNICATIONS, Vol: 4, ISSN: 2041-1723
  • Journal article
    Cargill P, 2013,

    SOLAR PHYSICS Towards ever smaller length scales

    , NATURE, Vol: 493, Pages: 485-486, ISSN: 0028-0836
  • Journal article
    Cui J, Lian Y, Mueller-Wodarg ICF, 2013,

    Compositional effects in Titan's thermospheric gravity waves

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 40, Pages: 43-47, ISSN: 0094-8276
  • Journal article
    Wicks RT, Mallet A, Horbury TS, Chen CHK, Schekochihin AA, Mitchell JJet al., 2013,

    Alignment and Scaling of Large-Scale Fluctuations in the Solar Wind

    , Physical Review Letters, Vol: 110, Pages: 025003-025003, ISSN: 0031-9007
  • Conference paper
    Masters A, Stawarz Ł, Fujimoto M, Schwartz SJ, Sergis N, Thomsen MF, Retinò A, Hasegawa H, Zieger B, Lewis GR, Coates AJ, Canu P, Dougherty MKet al., 2013,

    Electron acceleration to relativistic energies at a strong quasi-parallel shock wave

    Electrons can be accelerated to ultrarelativistic energies at strong (high-Mach number) collisionless shock waves that form when stellar debris rapidly expands after a supernova [4, 2, 19]. Collisionless shock waves also form in the flow of particles from the Sun (the solar wind), and extensive spacecraft observations have established that electron acceleration at these shocks is effectively absent whenever the upstream magnetic field is roughly parallel to the shock surface normal (quasi-parallel conditions) [16, 8, 10, 17, 14]. However, it is unclear whether this magnetic dependence of electron acceleration also applies to the far stronger shocks around young supernova remnants, where local magnetic conditions are poorly understood. Here we present Cassini spacecraft observations of an unusually strong solar system shock wave (Saturn’s bow shock) where significant local electron acceleration has been confirmed under quasi- parallel magnetic conditions for the first time, contradicting the established magnetic dependence of electron acceleration at solar system shocks [16, 8, 10, 17, 14]. Furthermore, the acceleration led to electrons at relativistic energies (∼ MeV), comparable to the highest energies ever attributed to shock-acceleration in the solar wind [16]. These observations suggest that at high-Mach numbers, like those of young supernova remnant shocks, quasi-parallel shocks become considerably more effective electron accelerators. For full details please see: Nature Physics, Volume 9, Issue 3, pp. 164-167.
  • Conference paper
    Seo Y, Chae KS, Mochizuki B, Clarino D, Yeung N, Yoon S, Seon J, Jin H, Lee DH, Lin RP, Sample J, Immel T, Brown P, Horbury TSet al., 2013,

    Instrument interface module between the on-board-computer and payloads in cinema CUBESAT as developed with FPGA

    , Pages: 4275-4281, ISSN: 0074-1795

    TRiplet Ionospheric Observatory-Cubesat for Ion, Neutral, Electron and MAgnetic fields (TRIO-CINEMA) is a space science mission consisting of three identical 3U CubeSats to provide stereo Energetic Neutral Atom (ENA) imaging of the ring current, multi-point in-situ measurement of supra thermal electrons and ions, and measurement of magnetic fields in Low Earth Orbit (LEO). Each spacecraft is equipped with a Supra Thermal Electrons, Ions, Neutrals (STEIN) instrument and a MAGnetometer from Imperial College (MAGIC) instrument in order to measure the plasma particles with diverse species and energies and magnetic fields. STEIN is able to distinguish electrons, ions, and neutrals by applying electric field in the entrance aperture. MAGIC is a dual 3-axis magnetoresistive sensor intended for attitude control and scientific measurement. The standard spacecraft CubeSat employed for the TRIO- CINEMA mission often utilizes Commercial-Off-The Shelf (COTS) electronics to build bus avionics that provides power and communications, whereas payloads are usually built in accordance with specific requirements that are often more demanding in terms of generation, transmission and storage of the data and power consumption. Therefore, designing and developing the interface to be compatible between mission payloads and the CubeSat avionics built with COTS will be required for many CubeSat missions. In this presentation, we describe the instrument interface module between the On-Board-Computer (OBC) and the mission payloads for TRIO-CINEMA spacecraft. The module is developed to provide required communication and power interfaces. In the instrument interface module, a Field Programmable Gate Array (FPGA) is employed to support computing power of the OBC and communication interfaces. It is exclusively operated as data buffer and framer for generated data from mission payloads and their subsequent transmission through S-band to the ground station. The interface module provides various elect
  • Journal article
    Nakamura R, Plaschke F, Teubenbacher R, Giner L, Baumjohann W, Magnes W, Steller M, Torbert RB, Vaith H, Chutter M, Fornacon K-H, Glassmeier K-H, Carr Cet al., 2013,

    Inter-instrument calibration using magnetic field data from Flux Gate Magnetometer (FGM) and Electron Drift Instrument (EDI) onboard Cluster

    , GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS, Vol: 3, Pages: 459-487, ISSN: 2193-0856
  • Journal article
    Pudney MA, Carr CM, Schwartz SJ, Howarth SIet al., 2013,

    Near equipment magnetic field verification and scaling

    , GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS, Vol: 3, Pages: 437-458, ISSN: 2193-0856
  • Journal article
    Kasahara S, Kronberg EA, Kimura T, Tao C, Badman SV, Masters A, Retino A, Krupp N, Fujimoto Met al., 2013,

    Asymmetric distribution of reconnection jet fronts in the Jovian nightside magnetosphere

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 118, Pages: 375-384, ISSN: 2169-9380
  • Journal article
    Orr A, Bracegirdle TJ, Hosking JS, Feng W, Roscoe HK, Haigh JDet al., 2013,

    Strong Dynamical Modulation of the Cooling of the Polar Stratosphere Associated with the Antarctic Ozone Hole

    , JOURNAL OF CLIMATE, Vol: 26, Pages: 662-668, ISSN: 0894-8755

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