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Journal articleHall RJ, Hanna E, Chen L, 2021,
Winter Arctic Amplification at the synoptic timescale, 1979-2018, its regional variation and response to tropical and extratropical variability
, CLIMATE DYNAMICS, Vol: 56, Pages: 457-473, ISSN: 0930-7575- Author Web Link
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- Citations: 10
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Journal articleBallinger TJ, Hanna E, Hall RJ, et al., 2021,
The role of blocking circulation and emerging open water feedbacks on Greenland cold-season air temperature variability over the last century
, INTERNATIONAL JOURNAL OF CLIMATOLOGY, Vol: 41, Pages: E2778-E2800, ISSN: 0899-8418- Author Web Link
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- Citations: 6
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Journal articleLiggins FS, Pickering JC, Nave G, et al., 2021,
The Spectrum and Term Analysis of Singly Ionized Manganese
, ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, Vol: 252, ISSN: 0067-0049- Cite
- Citations: 5
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Conference paperKromyda L, Malaspina DM, Ergun RE, et al., 2021,
Electrostatic Waves with Rapid Frequency Shifts in the Solar Wind from PSP observations
, United-States-National-Committee-of-URSI National Radio Science Meeting (USNC-URSI NRSM), Publisher: IEEE, Pages: 220-221 -
Book chapterNilsson H, Behar E, Burch JL, et al., 2021,
Birth of a Magnetosphere
, MAGNETOSPHERES IN THE SOLAR SYSTEM, Editors: Maggiolo, Andre, Hasegawa, Welling, Zhang, Paxton, Publisher: AMER GEOPHYSICAL UNION, Pages: 427-439, ISBN: 978-1-119-50752-9- Author Web Link
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- Citations: 2
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Book chapterSouthwood DJ, 2021,
A Brief History of the Magnetosphere
, MAGNETOSPHERES IN THE SOLAR SYSTEM, Editors: Maggiolo, Andre, Hasegawa, Welling, Zhang, Paxton, Publisher: AMER GEOPHYSICAL UNION, Pages: 3-13, ISBN: 978-1-119-50752-9 -
Book chapterKeeling RF, Graven HD, 2021,
Insights from Time Series of Atmospheric Carbon Dioxide and Related Tracers
, ANNUAL REVIEW OF ENVIRONMENT AND RESOURCES, VOL 46, 2021, Editors: Gadgil, Tomich, Publisher: ANNUAL REVIEWS, Pages: 85-110- Author Web Link
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- Citations: 12
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Journal articleEastwood JP, Goldman M, Phan TD, et al., 2020,
Energy flux densities near the electron dissipation region in asymmetric magnetopause reconnection
, Physical Review Letters, Vol: 125, Pages: 1-6, ISSN: 0031-9007Magnetic reconnection is of fundamental importance to plasmas because of its role in releasing and repartitioning stored magnetic energy. Previous results suggest that this energy is predominantly released as ion enthalpy flux along the reconnection outflow. Using Magnetospheric Multiscale data we find the existence of very significant electron energy flux densities in the vicinity of the magnetopause electron dissipation region, orthogonal to the ion energy outflow. These may significantly impact models of electron transport, wave generation, and particle acceleration.
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Journal articleFletcher LN, Simon AA, Hofstadter MD, et al., 2020,
Ice giant system exploration in the 2020s: an introduction
, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol: 378, Pages: 1-11, ISSN: 1364-503XThe international planetary science community met in London in January 2020, united in the goal of realizing the first dedicated robotic mission to the distant ice giants, Uranus and Neptune, as the only major class of solar system planet yet to be comprehensively explored. Ice-giant-sized worlds appear to be a common outcome of the planet formation process, and pose unique and extreme tests to our understanding of exotic water-rich planetary interiors, dynamic and frigid atmospheres, complex magnetospheric configurations, geologically-rich icy satellites (both natural and captured), and delicate planetary rings. This article introduces a special issue on ice giant system exploration at the start of the 2020s. We review the scientific potential and existing mission design concepts for an ambitious international partnership for exploring Uranus and/or Neptune in the coming decades.
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Journal articleMalik A, Nowack PJ, Haigh JD, et al., 2020,
Tropical Pacific climate variability under solar geoengineering: impacts on ENSO extremes
, ATMOSPHERIC CHEMISTRY AND PHYSICS, Vol: 20, Pages: 15461-15485, ISSN: 1680-7316 -
Journal articleMatteini L, Franci L, Alexandrova O, et al., 2020,
Magnetic field turbulence in the solar wind at sub-ion scales: in situ observations and numerical simulations
, Frontiers in Astronomy and Space Sciences, ISSN: 2296-987XWe investigate the transition of the solar wind turbulent cascade from MHD tosub-ion range by means of a detail comparison between in situ observations andhybrid numerical simulations. In particular we focus on the properties of themagnetic field and its component anisotropy in Cluster measurements and hybrid2D simulations. First, we address the angular distribution of wave-vectors inthe kinetic range between ion and electron scales by studying the varianceanisotropy of the magnetic field components. When taking into account thesingle-direction sampling performed by spacecraft in the solar wind, the mainproperties of the fluctuations observed in situ are also recovered in ournumerical description. This result confirms that solar wind turbulence in thesub-ion range is characterized by a quasi-2D gyrotropic distribution ofk-vectors around the mean field. We then consider the magnetic compressibilityassociated with the turbulent cascade and its evolution from large-MHD tosub-ion scales. The ratio of field-aligned to perpendicular fluctuations,typically low in the MHD inertial range, increases significantly when crossingion scales and its value in the sub-ion range is a function of the total plasmabeta only, as expected from theoretical predictions, with higher magneticcompressibility for higher beta. Moreover, we observe that this increase has agradual trend from low to high beta values in the in situ data; this behaviouris well captured by the numerical simulations. The level of magnetic fieldcompressibility that is observed in situ and in the simulations is in fairlygood agreement with theoretical predictions, especially at high beta,suggesting that in the kinetic range explored the turbulence is supported bylow-frequency and highly-oblique fluctuations in pressure balance, like kineticAlfv\'en waves or other slowly evolving coherent structures.
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Journal articleQuaas J, Arola A, Cairns B, et al., 2020,
Constraining the Twomey effect from satellite observations: Issues and perspectives
, Atmospheric Chemistry and Physics, Vol: 20, Pages: 15079-15099, ISSN: 1680-7316The Twomey effect describes the radiative forcing associated with a change in cloud albedo due to an increase in anthropogenic aerosol emissions. It is driven by the perturbation in cloud droplet number concentration (ΔNd, ant) in liquid-water clouds and is currently understood to exert a cooling effect on climate. The Twomey effect is the key driver in the effective radiative forcing due to aerosol–cloud interactions, but rapid adjustments also contribute. These adjustments are essentially the responses of cloud fraction and liquid water path to ΔNd, ant and thus scale approximately with it. While the fundamental physics of the influence of added aerosol particles on the droplet concentration (Nd) is well described by established theory at the particle scale (micrometres), how this relationship is expressed at the large-scale (hundreds of kilometres) perturbation, ΔNd, ant, remains uncertain. The discrepancy between process understanding at particle scale and insufficient quantification at the climate-relevant large scale is caused by co-variability of aerosol particles and updraught velocity and by droplet sink processes. These operate at scales on the order of tens of metres at which only localised observations are available and at which no approach yet exists to quantify the anthropogenic perturbation. Different atmospheric models suggest diverse magnitudes of the Twomey effect even when applying the same anthropogenic aerosol emission perturbation. Thus, observational data are needed to quantify and constrain the Twomey effect. At the global scale, this means satellite data. There are four key uncertainties in determining ΔNd, ant, namely the quantification of (i) the cloud-active aerosol – the cloud condensation nuclei (CCN) concentrations at or above cloud base, (ii) Nd, (iii) the statistical approach for inferring the sensitivity of Nd to aerosol particles from the satellite data and (iv) uncert
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Journal articleSchwartz SJ, Kucharek H, Farrugia CJ, et al., 2020,
Energy Conversion within Current Sheets in the Earth's Quasi-parallel Magnetosheath
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Journal articleSouthwood D, Kivelson M, 2020,
An improbable collaboration
, Journal of Geophysical Research: Space Physics, Vol: 125, ISSN: 2169-9380Fifty years of collaboration between the authors are reviewed. Common themes cover magnetospheric magnetohydrodynamic phenomena: MHD waves, wave‐particle interactions, circulation, global modes and field line resonances in the terrestrial context, and magnetosphere‐moon interactions, transport processes, instabilities and global structure in the magnetospheres of giant planets. Over the period reviewed, instrumentation has improved, particularly in particle detectors, and interpretations that seemed radical when first suggested are now supported by measurements and seem commonplace.
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Journal articlePalchetti L, Brindley H, Bantges R, et al., 2020,
FORUM: unique far-infrared satellite observations to better understand how Earth radiates energy to space
, Bulletin of the American Meteorological Society, Vol: 101, Pages: E2030-E2046, ISSN: 0003-0007The Outgoing Longwave Radiation (OLR) emitted to space is a fundamental component of the Earth’s energy budget. There are numerous, entangled physical processes that contribute to OLR and that are responsible for driving, and responding to, climate change. Spectrally-resolved observations can disentangle these processes, but technical limitations have precluded accurate space-based spectral measurements covering the far-infrared (FIR) from 100 to 667 cm−1 (wavelengths between 15 and 100 μm). The Earth’s FIR spectrum is thus essentially unmeasured even though at least half of the OLR arises from this spectral range. The region is strongly influenced by upper tropospheric/lower stratospheric water vapor, temperature lapse rate, ice cloud distribution and microphysics, all critical parameters in the climate system that are highly variable and still poorly observed and understood. To cover this uncharted territory in Earth observations, the Far-infrared Outgoing RadiationUnderstanding and Monitoring (FORUM) mission has recently been selected as ESA’s 9th Earth Explorer mission for launch in 2026. The primary goal of FORUM is to measure, with high absolute accuracy, the FIR component of the spectrally-resolved OLR for the first time with high spectral resolution and radiometric accuracy. The mission will provide a benchmark dataset of global observations which will significantly enhance our understanding of key forcing and feedback processes of the Earth’s atmosphere to enable more stringent evaluation of climate models. This paper describes the motivation for the mission, highlighting the scientific advances that are expected from the new measurements.
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Journal articleGoldman MV, Newman DL, Eastwood JP, et al., 2020,
Multibeam energy moments of multibeam particle velocity distributions
, Journal of Geophysical Research: Space Physics, Vol: 125, Pages: 1-19, ISSN: 2169-9380High‐resolution electron and ion velocity distributions, f(v), which consist of N effectively disjoint beams, have been measured by NASA's Magnetospheric Multiscale Mission and in reconnection simulations. Commonly used standard velocity moments assume a single mean‐flow velocity for the entire distribution. This can lead to counterintuitive results for a multibeam f(v). An example is the standard thermal energy density moment (at a given space‐time point) of a pair of equal and opposite cold particle beams. This standard moment is nonzero even though each beam has zero thermal energy density. By contrast, a multibeam moment of two or more cold beams at a given position and time has no thermal energy. A multibeam moment is obtained by taking a standard moment of each beam and then summing over beams. In this paper we will generalize these notions, explore their consequences, and apply them to an f(v) which is a sum of tri‐Maxwellians. Both standard and multibeam energy moments have coherent and incoherent pieces. Examples of incoherent moments are the thermal energy density, the pressure, and the thermal energy flux (enthalpy flux plus heat flux). Corresponding coherent moments are the bulk kinetic energy density, the ram pressure, and the bulk kinetic energy flux. The difference between a standard incoherent moment and its multibeam counterpart will be defined as the “pseudothermal part” of the standard moment. The sum of a pair of corresponding coherent and incoherent moments is the undecomposed moment. Undecomposed standard moments are always equal to the corresponding undecomposed multibeam moments.
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Journal articleDing M, Pickering JC, 2020,
Measurements of the hyperfine structure of atomic energy levels in Co ii
, Astrophysical Journal Supplement Series, Vol: 251, Pages: 1-7, ISSN: 0067-0049Analysis of hyperfine structure constants of singly ionized cobalt (Co II) were performed on cobalt spectra measured by Fourier transform spectrometers in the region 3000–63,000 cm−1 (33333 – 1587 Å). Fits to over 700 spectral lines led to measurements of 292 magnetic dipole hyperfine interaction A constants, with values between −32.5 mK and 59.5 mK (1 mK = 0.001 cm−1). Uncertainties of 255 A constants were between ±0.4 mK and ±3.0 mK, the remaining 37 ranged up to ±7 mK. The electric quadrupole hyperfine interaction B constant could be estimated for only one energy level. The number of Co II levels with known A values has now increased tenfold, improving and enabling the wider, more reliable, and accurate application of Co II in astronomical chemical abundance analyses.
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Journal articleBourouaine S, Perez JC, Klein KG, et al., 2020,
Turbulence Characteristics of Switchback and Nonswitchback Intervals Observed by Parker Solar Probe
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 904, ISSN: 2041-8205- Author Web Link
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- Citations: 24
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Journal articleEckardt FD, Bekiswa S, Von Holdt JR, et al., 2020,
South Africa's agricultural dust sources and events from MSG SEVIRI
, AEOLIAN RESEARCH, Vol: 47, ISSN: 1875-9637- Author Web Link
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- Citations: 7
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Journal articlePouquet A, Rosenberg D, Stawarz JE, 2020,
Interplay between turbulence and waves: large-scale helical transfer, and small-scale dissipation and mixing in fluid and Hall-MHD turbulence
, ATTI Della Accademia Nazionale Dei Lincei Rendiconti Lincei Scienze Fisiche e Naturali, Vol: 31, Pages: 949-961, ISSN: 2037-4631Novel features of turbulent flows have been analyzed recently, for example: (1) the possibility of an ideal invariant, such as the energy, to be transferred both to the small scales and to the large scales, in each case with a constant flux; (2) the existence of non-Gaussian wings in Probability Distribution Functions of kinetic, magnetic, and temperature fluctuations, together with their gradients, thus displaying large-scale as well as small-scale intermittency; and (3) the linear dependence on the control parameter of the effective dissipation in turbulence when non-linear eddies and waves interact. We shall briefly review these results with examples stemming from Solar Wind data, the atmosphere and the ocean with either magnetic fields, stratification, and/or rotation. In a second part, we shall examine numerically the inverse cascades of magnetic and of generalized helicity for Hall-MHD in the presence of forcing. These helical invariants in the ideal non-dissipative case involve various cross-correlations between the velocity and vorticity, the magnetic field, and the magnetic potential. For an ion inertial length larger than the forcing scale, the effect of the waves is significant. It leads to an exponential attenuation of the inverse cascade to large scales, since, through the velocity and vorticity, small scales play an increasing dynamical role for a strong Hall current.
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Journal articlePerrone D, Bruno R, D'Amicis R, et al., 2020,
Coherent Events at Ion Scales in the Inner Heliosphere: Parker Solar Probe Observations during the First Encounter
, ASTROPHYSICAL JOURNAL, Vol: 905, ISSN: 0004-637X- Author Web Link
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- Citations: 20
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Journal articleMagnes W, Hillenmaier O, Auster H-U, et al., 2020,
Space weather magnetometer aboard GEO-KOMPSAT-2A
, Space Science Reviews, Vol: 216, Pages: 1-36, ISSN: 0038-6308The South Korean meteorological and environmental satellite GEO-KOMPSAT-2A (GK-2A) was launched into geostationary orbit at 128.2∘ East on 4 December 2018. The space weather observation aboard GK-2A is performed by the Korea Space Environment Monitor. It consists of three particle detectors, a charging monitor and a four-sensor Service Oriented Spacecraft Magnetometer (SOSMAG).The magnetometer design aims for avoiding strict magnetic cleanliness requirements for the hosting spacecraft and an automated on-board correction of the dynamic stray fields which are generated by the spacecraft. This is achieved through the use of two science grade fluxgate sensors on an approximately one meter long boom and two additional magnetoresistance sensors mounted within the spacecraft body.This paper describes the instrument design, discusses the ground calibration methods and results, presents the post-launch correction and calibration achievements based on the data which were acquired during the first year in orbit and demonstrates the in-flight performance of SOSMAG with two science cases.The dynamic stray fields from the GK-2A spacecraft, which was built without specific magnetic cleanliness considerations, are reduced up to a maximum factor of 35. The magnitude of the largest remnant field from an active spacecraft disturber is 2.0 nT. Due to a daily shadowing of the SOSMAG boom, sensor intrinsic offset oscillations with a periodicity up to 60 minutes and peak-to-peak values up to 5 nT remain in the corrected data product.The comparison of the cleaned SOSMAG data with the Tsyganenko 2004 magnetic field model and the magnetic field data from the Magnetospheric Multiscale mission demonstrates that the offset error is less than the required 5 nT for all three components and that the drift of the offsets over 10 months is less than 7 nT.Future work will include a further reduction of the remaining artefacts in the final data product with the focus on lessening the temperature driv
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Journal articleHodnebrog Ø, Myhre G, Kramer RJ, et al., 2020,
The effect of rapid adjustments to halocarbons and N2O on radiative forcing
, npj Climate and Atmospheric Science, Vol: 3, Pages: 1-7, ISSN: 2397-3722Rapid adjustments occur after initial perturbation of an external climate driver (e.g., CO2) and involve changes in, e.g. atmospheric temperature, water vapour and clouds, independent of sea surface temperature changes. Knowledge of such adjustments is necessary to estimate effective radiative forcing (ERF), a useful indicator of surface temperature change, and to understand global precipitation changes due to different drivers. Yet, rapid adjustments have not previously been analysed in any detail for certain compounds, including halocarbons and N2O. Here we use several global climate models combined with radiative kernel calculations to show that individual rapid adjustment terms due to CFC-11, CFC-12 and N2O are substantial, but that the resulting flux changes approximately cancel at the top-of-atmosphere due to compensating effects. Our results further indicate that radiative forcing (which includes stratospheric temperature adjustment) is a reasonable approximation for ERF. These CFCs lead to a larger increase in precipitation per kelvin surface temperature change (2.2 ± 0.3% K−1) compared to other well-mixed greenhouse gases (1.4 ± 0.3% K−1 for CO2). This is largely due to rapid upper tropospheric warming and cloud adjustments, which lead to enhanced atmospheric radiative cooling (and hence a precipitation increase) and partly compensate increased atmospheric radiative heating (i.e. which is associated with a precipitation decrease) from the instantaneous perturbation.
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Journal articleMurray JE, Brindley HE, Fox S, et al., 2020,
Retrievals of high latitude surface emissivity across the infrared from high altitude aircraft flights
, Journal of Geophysical Research: Atmospheres, Vol: 125, Pages: 1-16, ISSN: 2169-897XWe present retrievals of infrared spectral surface emissivities spanning the far and mid infrared from aircraft observations over Greenland, taken at an altitude of 9.2 km above sea level. We describe the flight campaign, available measurements and the retrieval method. The principal barriers to reducing uncertainty in the emissivity retrievals are found to be instrumental noise and our ability to simultaneously retrieve the underlying surface temperature. However, our results indicate that using the instrumentation available to us it is possible to retrieve emissivities from altitude with an uncertainty of ~ 0.02 or better across much of the infrared. They confirm that the far‐infrared emissivity of snow and ice surfaces can depart substantially from unity, reaching values as low as 0.9 between 400‐450 cm‐1. They also show good consistency with retrievals from the same flight made from near‐surface observations giving confidence in the methodology used and the results obtained for this more challenging viewing configuration. To the best of our knowledge, this is the first time that far‐infrared surface emissivity has been retrieved from altitude and demonstrates that the methodology has the potential to be extended to planned satellite far‐infrared missions.
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Journal articleMansfield L, Nowack P, Kasoar M, et al., 2020,
Predicting global patterns of long-term climate change from short-term simulations using machine learning
, npj Climate and Atmospheric Science, Vol: 3, ISSN: 2397-3722Understanding and estimating regional climate change under different anthropogenic emission scenarios is pivotal for informing societal adaptation and mitigation measures. However, the high computational complexity of state-of-the-art climate models remains a central bottleneck in this endeavour. Here we introduce a machine learning approach, which utilises a unique dataset of existing climate model simulations to learn relationships between short-te¬rm and long-term temperature responses to different climate forcing scenarios. This approach not only has the potential to accelerate climate change projections by reducing the costs of scenario computations, but also helps uncover early indicators of modelled long-term climate responses, which is of relevance to climate change detection, predictability and attribution. Our results highlight challenges and opportunities for data-driven climate modelling, especially concerning the incorporation of even larger model datasets in the future. We therefore encourage extensive data sharing among research institutes to build ever more powerful climate response emulators, and thus to enable faster climate change projections.
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Journal articleCarnielli G, Galand M, Leblanc F, et al., 2020,
Simulations of ion sputtering at Ganymede
, Icarus, Vol: 351, Pages: 1-11, ISSN: 0019-1035Ganymede's surface is subject to constant bombardment by Jovian magnetospheric and Ganymede's ionospheric ions. These populations sputter the surface and contribute to the replenishment of the moon's exosphere.Thus far, estimates for sputtering on the moon's surface have included only the contribution from Jovian ions. In this work, we have used our recent model of Ganymede's ionosphere Carnielli et al., 2019 to evaluate the contribution of ionospheric ions for the first time. In addition, we have made new estimates for the contribution from Jovian ions, including both thermal and energetic components.For Jovian ions, we find a total sputtering rate of 2.2 × 1027 s−1, typically an order of magnitude higher compared to previous estimates. For ionospheric ions, produced through photo- and electron-impact ionization, we find values in the range 2.7 × 1026–5.2 × 1027 s−1 when the moon is located above the Jovian plasma sheet. Hence, Ganymede's ionospheric ions provide a contribution of at least 10% to the sputtering rate, and under certain conditions they dominate the process. This finding indicates that the ionospheric population is an important source to consider in the context of exospheric models.
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Journal articleDavies E, Forsyth R, Good S, et al., 2020,
On the radial and longitudinal variation of a magnetic cloud: ACE, wind, ARTEMIS and Juno observations
, Solar Physics: a journal for solar and solar-stellar research and the study of solar terrestrial physics, Vol: 295, ISSN: 0038-0938We present observations of the same magnetic cloud made near Earth by the Advance Composition Explorer (ACE), Wind, and the Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun (ARTEMIS) mission comprising the Time History of Events and Macroscale Interactions during Substorms (THEMIS) B and THEMIS C spacecraft, and later by Juno at a distance of 1.2 AU. The spacecraft were close to radial alignment throughout the event, with a longitudinal separation of 3.6∘ between Juno and the spacecraft near Earth. The magnetic cloud likely originated from a filament eruption on 22 October 2011 at 00:05 UT, and caused a strong geomagnetic storm at Earth commencing on 24 October. Observations of the magnetic cloud at each spacecraft have been analysed using minimum variance analysis and two flux rope fitting models, Lundquist and Gold–Hoyle, to give the orientation of the flux rope axis. We explore the effect different trailing edge boundaries have on the results of each analysis method, and find a clear difference between the orientations of the flux rope axis at the near-Earth spacecraft and Juno, independent of the analysis method. The axial magnetic field strength and the radial width of the flux rope are calculated using both observations and fitting parameters and their relationship with heliocentric distance is investigated. Differences in results between the near-Earth spacecraft and Juno are attributed not only to the radial separation, but to the small longitudinal separation which resulted in a surprisingly large difference in the in situ observations between the spacecraft. This case study demonstrates the utility of Juno cruise data as a new opportunity to study magnetic clouds beyond 1 AU, and the need for caution in future radial alignment studies.
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Journal articleBantges RJ, Brindley HE, Murray JE, et al., 2020,
A test of the ability of current bulk optical models to represent the radiative properties of cirrus cloud across the mid- and far-infrared
, Atmospheric Chemistry and Physics, Vol: 20, Pages: 12889-12903, ISSN: 1680-7316Measurements of mid- to far-infrared nadir radiances obtained from the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe 146 aircraft during the Cirrus Coupled Cloud-Radiation Experiment (CIRCCREX) are used to assess the performance of various ice cloud bulk optical property models. Through use of a minimization approach, we find that the simulations can reproduce the observed spectra in the mid-infrared to within measurement uncertainty, but they are unable to simultaneously match the observations over the far-infrared frequency range. When both mid- and far-infrared observations are used to minimize residuals, first-order estimates of the spectral flux differences between the best-performing simulations and observations indicate a compensation effect between the mid- and far-infrared such that the absolute broadband difference is < 0.7 W m−2. However, simply matching the spectra using the mid-infrared (far-infrared) observations in isolation leads to substantially larger discrepancies, with absolute differences reaching ∼ 1.8 (3.1) W m−2. These results show that simulations using these microphysical models may give a broadly correct integrated longwave radiative impact but that this masks spectral errors, with implicit consequences for the vertical distribution of atmospheric heating. They also imply that retrievals using these models applied to mid-infrared radiances in isolation will select cirrus optical properties that are inconsistent with far-infrared radiances. As such, the results highlight the potential benefit of more extensive far-infrared observations for the assessment and, where necessary, the improvement of current ice bulk optical models.
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Journal articleBunce EJ, Martindale A, Lindsay S, et al., 2020,
The BepiColombo Mercury Imaging X-Ray Spectrometer: Science Goals, Instrument Performance and Operations
, SPACE SCIENCE REVIEWS, Vol: 216, ISSN: 0038-6308- Author Web Link
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- Citations: 22
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Journal articleWoolley T, Matteini L, Horbury TS, et al., 2020,
Proton core behaviour inside magnetic field switchbacks
, Monthly Notices of the Royal Astronomical Society, Vol: 498, Pages: 5524-5531, ISSN: 0035-8711During Parker Solar Probe’s first two orbits there are widespread observations of rapid magnetic field reversals known as switchbacks. These switchbacks are extensively found in the near-Sun solar wind, appear to occur in patches, and have possible links to various phenomena such as magnetic reconnection near the solar surface. As switchbacks are associated with faster plasma flows, we questioned whether they are hotter than the background plasma and whether the microphysics inside a switchback is different to its surroundings. We have studied the reduced distribution functions from the Solar Probe Cup instrument and considered time periods with markedly large angular deflections, to compare parallel temperatures inside and outside switchbacks. We have shown that the reduced distribution functions inside switchbacks are consistent with a rigid velocity space rotation of the background plasma. As such, we conclude that the proton core parallel temperature is very similar inside and outside of switchbacks, implying that a T-V relationship does not hold for the proton core parallel temperature inside magnetic field switchbacks. We further conclude that switchbacks are consistent with Alfvénic pulses travelling along open magnetic field lines. The origin of these pulses, however, remains unknown. We also found that there is no obvious link between radial Poynting flux and kinetic energy enhancements suggesting that the radial Poynting flux is not important for the dynamics of switchbacks.
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