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  • Journal article
    Lai T-K, Hendricks EA, Menelaou K, Yau MKet al., 2021,

    Roles of Barotropic Instability across the Moat in Inner Eyewall Decay and Outer Eyewall Intensification: Three-Dimensional Numerical Experiments

    , JOURNAL OF THE ATMOSPHERIC SCIENCES, Vol: 78, Pages: 473-496, ISSN: 0022-4928
  • Journal article
    Jannet G, de Wit TD, Krasnoselskikh V, Kretzschmar M, Fergeau P, Bergerard-Timofeeva M, Agrapart C, Brochot J-Y, Chalumeau G, Martin P, Revillet C, Bale SD, Maksimovic M, Bowen TA, Brysbaert C, Goetz K, Guilhem E, Harvey PR, Leray V, Lorfevre Eet al., 2021,

    Measurement of Magnetic Field Fluctuations in the Parker Solar Probe and Solar Orbiter Missions

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
  • Journal article
    Agiwal O, Cao H, Cowley SWH, Dougherty MK, Hunt GJ, Muller-Wodarg I, Achilleos Net al., 2021,

    Constraining the Temporal Variability of Neutral Winds in Saturn's Low-Latitude Ionosphere Using Magnetic Field Measurements

    , JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, Vol: 126, ISSN: 2169-9097
  • Journal article
    Madanian H, Desai M, Schwartz SJ, Wilson LB, Fuselier SA, Burch JL, Le Contel O, Turner DL, Ogasawara K, Brosius AL, Russell CT, Ergun RE, Ahmadi N, Gershman DJ, Lindqvist P-Aet al., 2021,

    The Dynamics of a High Mach Number Quasi-perpendicular Shock: MMS Observations

    , ASTROPHYSICAL JOURNAL, Vol: 908, ISSN: 0004-637X
  • Journal article
    Liggins FS, Pickering JC, Nave G, Kramida A, Gamrath S, Quinet Pet al., 2021,

    New Ritz Wavelengths and Transition Probabilities of Parity-forbidden [Mn II] Lines of Astrophysical Interest

    , ASTROPHYSICAL JOURNAL, Vol: 907, ISSN: 0004-637X
  • Journal article
    Shi C, Zhao J, Huang J, Wang T, Wu D, Chen Y, Hu Q, Kasper JC, Bale SDet al., 2021,

    Parker Solar Probe Observations of Alfvenic Waves and Ion-cyclotron Waves in a Small-scale Flux Rope

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 908, ISSN: 2041-8205
  • Journal article
    Chandler MO, Schwartz SJ, Avanov LA, Coffey VN, Giles BL, Moore TE, Pollock CJ, Burch JL, Russell CT, Torbert RBet al., 2021,

    Observations of Mirror Mode Structures in the Dawn-Side Magnetosphere

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 126, ISSN: 2169-9380
  • Journal article
    Choi KTH, Brindley H, 2021,

    COVID-19 lockdown air quality change implications for solar energy generation over China

    , Environmental Research Letters, Vol: 16, Pages: 1-10, ISSN: 1748-9326

    We exploit changes in air quality seen during the COVID-19 lockdown over China to show how a cleaner atmosphere has notable co-benefits for solar concentrator photovoltaic energy generation. We use satellite observations and analyses of the atmospheric state to simulate surface broadband and spectrally resolved direct normal irradiance (DNI). Over Wuhan, the first city placed under lockdown, we show how the atmospheric changes not only lead to a 19.8% increase in broadband DNI but also induce a significant blue-shift in the DNI spectrum. Feeding these changes into a solar cell simulator results in a 29.7% increase in the power output for a typical triple-junction photovoltaic cell, with around one-third of the increase arising from enhanced cell efficiency due to improved spectral matching. Our estimates imply that these increases in power and cell efficiency would have been realised over many parts of China during the lockdown period. This study thus demonstrates how a cleaner atmosphere may enable more efficient large scale solar energy generation. We conclude by setting our results in the context of future climate change mitigation and air pollution policies.
  • Journal article
    Toumi R, Wang S, 2021,

    Recent migration of tropical cyclones toward coasts

    , Science, Vol: 371, Pages: 514-517, ISSN: 0036-8075

    Poleward migrations of tropical cyclones have been observed globally, but their impact on coastal areas remains unclear. We investigated the change in global tropical cyclone activity in coastal regions over the period 1982–2018. We found that the distance of tropical cyclone maximum intensity to land has decreased by about 30 kilometers per decade, and that the annual frequency of global tropical cyclones increases with proximity to land by about two additional cyclones per decade. Trend analysis reveals a robust migration of tropical cyclone activity toward coasts, concurrent with poleward migration of cyclone locations as well as a statistically significant westward shift. This zonal shift of tropical cyclone tracks may be mainly driven by global zonal changes in environmental steering flow.
  • Journal article
    Bowen TA, Bale SD, Bandyopadhyay R, Bonnell JW, Case A, Chasapis A, Chen CHK, Curry S, de Wit TD, Goetz K, Goodrich K, Gruesbeck J, Halekas J, Harvey PR, Howes GG, Kasper JC, Korreck K, Larson D, Livi R, MacDowall RJ, Malaspina DM, Mallet A, McManus MD, Page B, Pulupa M, Raouafi N, Stevens ML, Whittlesey Pet al., 2021,

    Kinetic-Scale Turbulence in the Venusian Magnetosheath

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 48, ISSN: 0094-8276
  • Journal article
    Heiter U, Lind K, Bergemann M, Asplund M, Mikolaitis S, Barklem PS, Masseron T, de Laverny P, Magrini L, Edvardsson B, Jonsson H, Pickering JC, Ryde N, Aran AB, Bensby T, Casey AR, Feltzing S, Jofre P, Korn AJ, Pancino E, Damiani F, Lanzafame A, Lardo C, Monaco L, Morbidelli L, Smiljanic R, Worley C, Zaggia S, Randich S, Gilmore GFet al., 2021,

    Atomic data for the Gaia-ESO Survey

    , ASTRONOMY & ASTROPHYSICS, Vol: 645, ISSN: 0004-6361
  • Journal article
    Gunell H, Goetz C, Odelstad E, Beth A, Hamrin M, Henri P, Johansson FL, Nilsson H, Wieser GSet al., 2021,

    Ion acoustic waves near a comet nucleus: Rosetta observations at comet 67P/Churyumov-Gerasimenko

    , ANNALES GEOPHYSICAE, Vol: 39, Pages: 53-68, ISSN: 0992-7689
  • Conference paper
    Saboya E, Zazzeri G, Graven H, Manning AJ, Michel SEet al., 2021,

    Continuous CH₄ and δ¹³CH₄ Measurements in London Demonstrate Under-Reported Natural Gas Leakage
  • Book chapter
    Dunlop MW, Wang TY, Dong XC, Haarland S, Shi QQ, Fu HS, De Keyser J, Shen C, Rong ZJ, Escoubet CP, Pu ZY, Eastwood Jet al., 2021,

    Multispacecraft Measurements in the Magnetosphere

    , Magnetospheres in the Solar System, Pages: 637-656

    This chapter covers a selection of the range of multispacecraft techniques that have been initially developed to analyze Cluster data. We begin the chapter with a short introduction, following this with an account of the methods and their application. The topics are separated into those dealing with magnetic field gradients and topology (which include the curlometer, magnetic rotation analysis, and least squares approach); magnetic field reconstruction and the analysis of magnetic field nulls (which are significant for magnetic reconnection and other geometries); time series analysis, adapted for multispacecraft data (including boundary identification, dimensional, and motion analysis); and wave vector analysis methods in the Fourier domain.
  • Journal article
    Liggins FS, Pickering JC, Nave G, Ward JW, Tchang-Brillet W-ULet al., 2021,

    The Spectrum and Term Analysis of Singly Ionized Manganese

    , ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, Vol: 252, ISSN: 0067-0049
  • Journal article
    Ballinger TJ, Hanna E, Hall RJ, Carr JR, Brasher S, Osterberg EC, Cappelen J, Tedesco M, Ding Q, Mernild SHet 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
  • Journal article
    Stawarz JE, Matteini L, Parashar TN, Franci L, Eastwood JP, Gonzalez CA, Gingell IL, Burch JL, Ergun RE, Ahmadi N, Giles BL, Gershman DJ, Le Contel O, Lindqvist P, Russell CT, Strangeway RJ, Torbert RBet al., 2021,

    Comparative analysis of the various generalized Ohm's law terms in magnetosheath turbulence as observed by magnetospheric multiscale

    , Journal of Geophysical Research: Space Physics, Vol: 126, Pages: 1-14, ISSN: 2169-9380

    Decomposing the electric field (E) into the contributions from generalized Ohm's law provides key insight into both nonlinear and dissipative dynamics across the full range of scales within a plasma. Using high‐resolution, multi‐spacecraft measurements of three intervals in Earth's magnetosheath from the Magnetospheric Multiscale mission, the influence of the magnetohydrodynamic, Hall, electron pressure, and electron inertia terms from Ohm's law, as well as the impact of a finite electron mass, on the turbulent E spectrum are examined observationally for the first time. The magnetohydrodynamic, Hall, and electron pressure terms are the dominant contributions to E over the accessible length scales, which extend to scales smaller than the electron inertial length at the greatest extent, with the Hall and electron pressure terms dominating at sub‐ion scales. The strength of the non‐ideal electron pressure contribution is stronger than expected from linear kinetic Alfvén waves and a partial anti‐alignment with the Hall electric field is present, linked to the relative importance of electron diamagnetic currents in the turbulence. The relative contribution of linear and nonlinear electric fields scale with the turbulent fluctuation amplitude, with nonlinear contributions playing the dominant role in shaping E for the intervals examined in this study. Overall, the sum of the Ohm's law terms and measured E agree to within ∼ 20% across the observable scales. These results both confirm general expectations about the behavior of E in turbulent plasmas and highlight features that should be explored further theoretically.
  • Journal article
    Hall 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
  • Journal article
    Hanna E, Cappelen J, Fettweis X, Mernild SH, Mote TL, Mottram R, Steffen K, Ballinger TJ, Hall Ret al., 2021,

    Greenland surface air temperature changes from 1981 to 2019 and implications for ice-sheet melt and mass-balance change

    , INTERNATIONAL JOURNAL OF CLIMATOLOGY, Vol: 41, Pages: E1336-E1352, ISSN: 0899-8418
  • Book chapter
    Keeling 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
  • Book chapter
    Southwood 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 chapter
    Nilsson H, Behar E, Burch JL, Carr CM, Eriksson AI, Glassmeier K-H, Henri P, Galand M, Goetz C, Gunell H, Karlsson Tet 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
  • Conference paper
    Kromyda L, Malaspina DM, Ergun RE, Halekas J, Stevens ML, Verniero J, Chasapis A, Vech D, Bale SD, Bonnell JW, de Wit TD, Goetz K, Goodrich K, Harvey PR, MacDowall RJ, Pulupa M, Case AW, Kasper JC, Korreck KE, Larson D, Livi R, Whittlesey Pet 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
  • Journal article
    Eastwood JP, Goldman M, Phan TD, Stawarz JE, Cassak PA, Drake JF, Newman D, Lavraud B, Shay MA, Ergun RE, Burch JL, Gershman DJ, Giles BL, Lindqvist PA, Torbert RB, Strangeway RJ, Russell CTet al., 2020,

    Energy flux densities near the electron dissipation region in asymmetric magnetopause reconnection

    , Physical Review Letters, Vol: 125, Pages: 1-6, ISSN: 0031-9007

    Magnetic 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.
  • Journal article
    Fletcher LN, Simon AA, Hofstadter MD, Arridge CS, Cohen IJ, Masters A, Mandt K, Coustenis Aet 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: 1364-503X

    The 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.
  • Journal article
    Malik A, Nowack PJ, Haigh JD, Cao L, Atique L, Plancherel Yet 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 article
    Matteini L, Franci L, Alexandrova O, Lacombe C, Landi S, Hellinger P, Papini E, Verdini Aet 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: 2296-987X

    We 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.
  • Journal article
    Quaas J, Arola A, Cairns B, Christensen M, Deneke H, Ekman AML, Feingold G, Fridlind A, Gryspeerdt E, Hasekamp O, Li Z, Lipponen A, Ma P-L, Mülmenstädt J, Nenes A, Penner J, Rosenfeld D, Schrödner R, Sinclair K, Sourdeval O, Stier P, Tesche M, van Diedenhoven B, Wendisch Met al., 2020,

    Constraining the Twomey effect from satellite observations: Issues and perspectives

    , Atmospheric Chemistry and Physics, Vol: 20, Pages: 15079-15099, ISSN: 1680-7316

    The 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
  • Journal article
    Schwartz SJ, Kucharek H, Farrugia CJ, Trattner K, Gingell I, Ergun RE, Strangeway RJ, Gershman DJet al., 2020,

    Energy Conversion within Current Sheets in the Earth's Quasi-parallel Magnetosheath
  • Journal article
    Goldman MV, Newman DL, Eastwood JP, Lapenta Get al., 2020,

    Multibeam energy moments of multibeam particle velocity distributions

    , Journal of Geophysical Research: Space Physics, Vol: 125, Pages: 1-19, ISSN: 2169-9380

    High‐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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