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Journal articleCorti C, Whitman K, Desai R, et al., 2022, , White Paper submitted to Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033
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Journal articleKaweeyanun N, Masters A, 2022,
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Journal articleEggington J, Coxon J, Shore R, et al., 2022, , Frontiers in Astronomy and Space Sciences, Vol: 9, Pages: 1-17, ISSN: 2296-987X
The response of the Earth’s magnetotail current sheet to the external solar wind driver is highly time-dependent and asymmetric. For example, the current sheet twists in response to variations in the By component of the interplanetary magnetic field (IMF), and is hinged by the dipole tilt. Understanding the timescales over which these asymmetries manifest is of particular importance during geomagnetic storms when the dynamics of the tail control substorm activity. To investigate this, we use the Gorgon MHD model to simulate a geomagnetic storm which commenced on 3 May 2014, and was host to multiple By and Bz reversals and a prolonged period of southward IMF driving. We find that the twisting of the current sheet is well-correlated to IMF By throughout the event, with the angle of rotation increasing linearly with downtail distance and being morepronounced when the tail contains less open flux. During periods of southward IMF the twisting of the central current sheet responds most strongly at a timelag of ∼ 100 min for distances beyond 20 RE, consistent with the 1-2 hr convection timescale identified in the open flux content. Under predominantly northward IMF the response of the twisting is bimodal, with the strongest correlations between 15-40 RE downtail being at a shorter timescale of ∼ 30 min consistent with that estimated for induced By due to wave propagation, compared to a longer timescale of ∼ 3 hr further downtail again attributed to convection. This indicates that asymmetries in the magnetotail communicated by IMF By are influenced mostly by global convection during strong solar wind driving, but that more prompt induced By effects can dominate in the near-Earth tail and during periods of weaker driving. These results provide new insight into the characteristic timescales of solar wind-magnetosphere-ionosphere coupling.
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Journal articleNair R, Halekas JS, Whittlesey PL, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X
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- Citations: 3
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Conference paperStephenson P, Altwegg K, Beth A, et al., 2022, , Publisher: Copernicus GmbH
<jats:p>&lt;p&gt;The Rosetta spacecraft escorted comet 67P/Churyumov-Gerasimenko for two years along its orbit, from Aug 2014 to Sep 2016, observing the evolution of the comet from a close perspective. The Rosetta Plasma Consortium (RPC) monitored the plasma environment at the spacecraft throughout the escort phase.&lt;/p&gt;&lt;p&gt;Cometary electrons are produced by ionization of the neutral gas coma. This occurs through photoionization by extreme ultraviolet photons, and through electron-impact ionization (EII) by collisions of energetic electrons with the coma. Far from perihelion, EII is, at times, more prevalent than photoionization (Galand et al., 2016; Heritier et al., 2018), but the EII frequency has not been assessed across the whole mission. The source of the cometary electrons, and the origin of the ionizing electrons is still unclear.&lt;/p&gt;&lt;p&gt;We have calculated the electron impact ionization (EII) frequency throughout the Rosetta mission and at its location from measurements of RPC&amp;#8217;s Ion and Electron Sensor (RPC/IES). EII ionization is confirmed as the dominant source of cometary electrons and ions when far from perihelion but is much more variable than photoionization. We compare the EII frequency with properties of the neutral coma and cometary plasma to identify key drivers of the energetic electron population. The EII frequency is structured by outgassing rate and magnetic field strength.&lt;/p&gt;&lt;p&gt;The first 3D collision model of electrons at a comet (Stephenson et al. 2022) is also utilised to assess the origin of electrons within the coma. The model uses self-consistently calculated electric and magnetic fields from a fully-kinetic and collisionless Particle-in-Cell model (Deca et al. 2017, 2019)as an input. The modelling approach confirms cometary electrons are produced by impacts of energetic e
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Conference paperLewis Z, Beth A, Altwegg K, et al., 2022, , Publisher: Copernicus GmbH
<jats:p>&lt;p&gt;The European Space Agency Rosetta mission escorted comet 67P/Churyumov-Gerasimenko for two years, during which it acquired an extensive dataset, revealing unprecedented detail about the neutral and plasma environment of the coma. The measurements were made over a large range of heliocentric distances, and therefore of outgassing activities, as Rosetta witnessed 67P evolve from a low-activity icy body at 3.8 AU to a dynamic object with large-scale plasma structures and rich ion and neutral chemistry near perihelion at 1.2 AU. One such plasma structure is the diamagnetic cavity, a region of negligible magnetic field surrounding the comet nucleus. It is formed through the interaction of the unmagnetized outwardly expanding cometary plasma with the incoming solar wind. This region was encountered many times by Rosetta between April 2015 and February 2016, as the comet moved towards and away from perihelion.&lt;/p&gt;&lt;p&gt;In this study, we focus on the changing role of chemistry during the escort phase, particularly on trends in the detection of high proton affinity species near perihelion and within the diamagnetic cavity. NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt; is produced through the protonation of NH&lt;sub&gt;3&lt;/sub&gt; which has the highest proton affinity of the neutral species and is therefore the terminal ion. The ratio of this species to the major ion species H&lt;sub&gt;3&lt;/sub&gt;O&lt;sup&gt;+&lt;/sup&gt; can then be an indicator of the importance of ion-neutral chemistry as an ion loss process compared to transport. We use data from the high resolution mode of the ROSINA (Rosetta Orbital Spectrometer for Ion-Neutral Analysis)/DFMS (Double Focussing Mass Spectrometer) instrument, which allows certain ions of the
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Journal articleHalekas JS, Whittlesey P, Larson DE, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X
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- Citations: 32
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Journal articleMalaspina DM, Chasapis A, Tatum P, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X
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- Citations: 11
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Journal articleTigik SF, Vaivads A, Malaspina DM, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X
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- Citations: 9
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Journal articleAizawa S, Persson M, Menez T, et al., 2022, , PLANETARY AND SPACE SCIENCE, Vol: 218, ISSN: 0032-0633
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- Citations: 3
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Journal articleDing M, Pickering JC, 2022, , JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER, Vol: 288, ISSN: 0022-4073
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- Citations: 3
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Journal articleFranci L, Papini E, Del Sarto D, et al., 2022, , UNIVERSE, Vol: 8
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- Citations: 3
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Journal articleTeoh R, Schumann U, Gryspeerdt E, et al., 2022, , Atmospheric Chemistry and Physics, Vol: 22, Pages: 10919-10935, ISSN: 1680-7316
Around 5 % of anthropogenic radiative forcing (RF) is attributed to aviation CO2 and non-CO2 impacts. This paper quantifies aviation emissions and contrail climate forcing in the North Atlantic, one of the world's busiest air traffic corridors, over 5 years. Between 2016 and 2019, growth in CO2 (+3.13 % yr−1) and nitrogen oxide emissions (+4.5 % yr−1) outpaced increases in flight distance (+3.05 % yr−1). Over the same period, the annual mean contrail cirrus net RF (204–280 mW m−2) showed significant inter-annual variability caused by variations in meteorology. Responses to COVID-19 caused significant reductions in flight distance travelled (−66 %), CO2 emissions (−71 %) and the contrail net RF (−66 %) compared with the prior 1-year period. Around 12 % of all flights in this region cause 80 % of the annual contrail energy forcing, and the factors associated with strongly warming/cooling contrails include seasonal changes in meteorology and radiation, time of day, background cloud fields, and engine-specific non-volatile particulate matter (nvPM) emissions. Strongly warming contrails in this region are generally formed in wintertime, close to the tropopause, between 15:00 and 04:00 UTC, and above low-level clouds. The most strongly cooling contrails occur in the spring, in the upper troposphere, between 06:00 and 15:00 UTC, and without lower-level clouds. Uncertainty in the contrail cirrus net RF (216–238 mW m−2) arising from meteorology in 2019 is smaller than the inter-annual variability. The contrail RF estimates are most sensitive to the humidity fields, followed by nvPM emissions and aircraft mass assumptions. This longitudinal evaluation of aviation contrail impacts contributes a quantified understanding of inter-annual variability and informs strategies for contrail mitigation.
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Journal articleSharan S, Langlais B, Amit H, et al., 2022, , GEOPHYSICAL RESEARCH LETTERS, Vol: 49, ISSN: 0094-8276
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- Citations: 13
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Journal articleWang S, Toumi R, 2022, , Sci Rep, Vol: 12
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Journal articleClear CP, Pickering JC, Nave G, et al., 2022, , The Astrophysical Journal Supplement Series, Vol: 261, Pages: 35-35, ISSN: 0067-0049
High-resolution spectra of singly ionized nickel (Ni ii) have been recorded using Fourier transform spectroscopy in the region 143–5555 nm (1800–70,000 cm−1) with continuous, nickel–helium hollow cathode discharge sources. An extensive analysis of identified Ni ii lines resulted in the confirmation and revision of 283 previously reported energy levels, from the ground state up to the 3d8(ML)6s subconfigurations. Typical energy-level uncertainties are a few thousandths of a cm−1, representing at least an order-of-magnitude reduction in uncertainty with respect to previous measurements. Twenty-five new energy levels have now been established and are reported here for the first time. Eigenvector compositions of the energy levels have been calculated using the orthogonal operator method. In total, 159 even and 149 odd energy levels and 1424 classified line wavelengths of Ni ii are reported and will enable more accurate and reliable analyses of Ni ii in astrophysical spectra.
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Journal articleSulaiman A, Mauk B, Szalay J, et al., 2022, , Journal of Geophysical Research: Space Physics, Vol: 127, ISSN: 2169-9380
The Juno spacecraft's polar orbits have enabled direct sampling of Jupiter's low-altitude auroral field lines. While various data sets have identified unique features over Jupiter's main aurora, they are yet to be analyzed altogether to determine how they can be reconciled and fit into the bigger picture of Jupiter's auroral generation mechanisms. Jupiter's main aurora has been classified into distinct “zones”, based on repeatable signatures found in energetic electron and proton spectra. We combine fields, particles, and plasma wave data sets to analyze Zone-I and Zone-II, which are suggested to carry upward and downward field-aligned currents, respectively. We find Zone-I to have well-defined boundaries across all data sets. H+ and/or H3+ cyclotron waves are commonly observed in Zone-I in the presence of energetic upward H+ beams and downward energetic electron beams. Zone-II, on the other hand, does not have a clear poleward boundary with the polar cap, and its signatures are more sporadic. Large-amplitude solitary waves, which are reminiscent of those ubiquitous in Earth's downward current region, are a key feature of Zone-II. Alfvénic fluctuations are most prominent in the diffuse aurora and are repeatedly found to diminish in Zone-I and Zone-II, likely due to dissipation, at higher altitudes, to energize auroral electrons. Finally, we identify significant electron density depletions, by up to 2 orders of magnitude, in Zone-I, and discuss their important implications for the development of parallel potentials, Alfvénic dissipation, and radio wave generation.
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Journal articleZhao L-L, Zank GP, Adhikari L, et al., 2022, , ASTROPHYSICAL JOURNAL LETTERS, Vol: 934, ISSN: 2041-8205
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- Citations: 25
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Journal articleShi C, Panasenco O, Velli M, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 934, ISSN: 0004-637X
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- Citations: 25
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Journal articleSioulas N, Huang Z, Velli M, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 934, ISSN: 0004-637X
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- Citations: 20
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Journal articleErgun RE, Pathak N, Usanova ME, et al., 2022, , ASTROPHYSICAL JOURNAL LETTERS, Vol: 935, ISSN: 2041-8205
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- Citations: 19
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Journal articleRasca AP, Farrell WM, Whittlesey PL, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 935, ISSN: 0004-637X
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- Citations: 4
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Journal articleTelloni D, Zank GP, Sorriso-Valvo L, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 935, ISSN: 0004-637X
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- Citations: 12
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Journal articlePark C, Shin S-W, Kim G, et al., 2022, , RENEWABLE ENERGY, Vol: 195, Pages: 1480-1480, ISSN: 0960-1481
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- Citations: 1
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Journal articleBrunmayr AS, Graven H, 2022,
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Journal articleSchwartz SJ, Goodrich KA, III LBW, et al., 2022,
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Journal articleGraven H, Keeling R, Xu X, 2022, , NATURE, Vol: 607, Pages: 449-449, ISSN: 0028-0836
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- Citations: 1
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Journal articleKilpua EKJ, Good SW, Ala-Lahti M, et al., 2022, , ASTRONOMY & ASTROPHYSICS, Vol: 663, ISSN: 0004-6361
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- Citations: 9
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Journal articleFargette N, Lavraud B, Rouillard AP, et al., 2022, , ASTRONOMY & ASTROPHYSICS, Vol: 663, ISSN: 0004-6361
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- Citations: 21
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Journal articleTrotta D, Pecora F, Settino A, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 933, ISSN: 0004-637X
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- Citations: 7
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