Search or filter publications

Filter by type:

Filter by publication type

Filter by year:

to

Results

  • Showing results for:
  • Reset all filters

Search results

  • Journal article
    Sioulas N, Velli M, Chhiber R, Vlahos L, Matthaeus WH, Bandyopadhyay R, Cuesta ME, Shi C, Bowen TA, Qudsi RA, Stevens ML, Bale SDet al., 2022,

    Statistical Analysis of Intermittency and its Association with Proton Heating in the Near-Sun Environment

    , ASTROPHYSICAL JOURNAL, Vol: 927, ISSN: 0004-637X
  • Journal article
    Mozer FS, Bale SD, Cattell CA, Halekas J, Vasko IY, Verniero JL, Kellogg PJet al., 2022,

    Core Electron Heating by Triggered Ion Acoustic Waves in the Solar Wind

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 927, ISSN: 2041-8205
  • Journal article
    Reville V, Velli M, Panasenco O, Tenerani A, Shi C, Badman ST, Bale SD, Kasper JC, Stevens ML, Korreck KE, Bonnell JW, Case AW, Dudok de Wit T, Goetz K, Harvey PR, Larson DE, Livi R, Malaspina DM, MacDowall RJ, Pulupa M, Whittlesey PLet al., 2022,

    The Role of Alfven Wave Dynamics on the Large-scale Properties of the Solar Wind: Comparing an MHD Simulation with Parker Solar Probe E1 data (vol 246. 24, 2020)

    , ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, Vol: 259, ISSN: 0067-0049
  • Journal article
    Desai M, Mitchell DG, McComas DJ, Drake JF, Phan T, Szalay JR, Roelof EC, Giacalone J, Hill ME, Christian ER, Schwadron NA, McNutt RL, Wiedenbeck ME, Joyce C, Cohen CMS, Davis AJ, Krimigis SM, Leske RA, Matthaeus WH, Malandraki O, Mewaldt RA, Labrador A, Stone EC, Bale SD, Verniero J, Rahmati A, Whittlesey P, Livi R, Larson D, Pulupa M, MacDowall RJ, Niehof JT, Kasper JC, Horbury TSet al., 2022,

    Suprathermal ion energy spectra and anisotropies near the heliospheric current sheet crossing observed by the Parker Solar Probe during encounter 7

    , The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 927, Pages: 1-12, ISSN: 0004-637X

    We present observations of ≳10–100 keV nucleon−1 suprathermal (ST) H, He, O, and Fe ions associated with crossings of the heliospheric current sheet (HCS) at radial distances of <0.1 au from the Sun. Our key findings are as follows: (1) very few heavy ions are detected during the first full crossing, the heavy-ion intensities are reduced during the second partial crossing and peak just after the second crossing; (2) ion arrival times exhibit no velocity dispersion; (3) He pitch-angle distributions track the magnetic field polarity reversal and show up to ∼10:1 anti-sunward, field-aligned flows and beams closer to the HCS that become nearly isotropic farther from the HCS; (4) the He spectrum steepens either side of the HCS, and the He, O, and Fe spectra exhibit power laws of the form ∼E−4–E6; and (5) maximum energies EX increase with the ion's charge-to-mass (Q/M) ratio as ${E}_{X}/{E}_{H}\propto {({Q}_{X}/{M}_{X})}^{\delta }$, where δ ∼ 0.65–0.76, assuming that the average Q states are similar to those measured in gradual and impulsive solar energetic particle events at 1 au. The absence of velocity dispersion in combination with strong field-aligned anisotropies closer to the HCS appears to rule out solar flares and near-Sun coronal-mass-ejection-driven shocks. These new observations present challenges not only for mechanisms that employ direct parallel electric fields and organize maximum energies according to E/Q but also for local diffusive and magnetic-reconnection-driven acceleration models. Reevaluation of our current understanding of the production and transport of energetic ions is necessary to understand this near-solar, current-sheet-associated population of ST ions.

  • Journal article
    Larosa A, Dudok de Wit T, Krasnoselskikh V, Bale SD, Agapitov O, Bonnell J, Froment C, Goetz K, Harvey P, Halekas J, Kretzschmar M, MacDowall R, Malaspina DM, Moncuquet M, Niehof J, Pulupa M, Revillet Cet al., 2022,

    Langmuir-Slow Extraordinary Mode Magnetic Signature Observations with Parker Solar Probe

    , ASTROPHYSICAL JOURNAL, Vol: 927, ISSN: 0004-637X
  • Journal article
    Wang S, Toumi R, 2022,

    On the intensity decay of tropical cyclones before landfall

    , Scientific Reports, Vol: 12, ISSN: 2045-2322

    It remains unclear how tropical cyclones (TCs) decay from their ocean lifetime maximum intensity (LMI) to landfall intensity (LI), yet this stage is of fundamental importance governing the socio-economic impact of TCs. Here we show that TCs decay on average by 25% from LMI to LI. A logistic decay model of energy production by ocean enthalpy input and surface dissipation by frictional drag, can physically connect the LMI to LI. The logistic model fits the observed intensity decay as well as an empirically exponential decay does, but with a clear physical foundation. The distance between locations of LMI and TC landfall is found to dominate the variability of the decay from the LMI to LI, whereas environmental conditions are generally less important. A major TC at landfall typically has a very large LMI close to land. The LMI depends on the heating by ocean warming, but the LMI location is also important to future landfall TC intensity changes which are of socio-economic importance.

  • Journal article
    Trofimov H, Post P, Gryspeerdt E, Toll Vet al., 2022,

    Meteorological conditions favorable for strong anthropogenic aerosol impacts on clouds

    , Journal of Geophysical Research: Atmospheres, Vol: 127, ISSN: 2169-897X

    Ship-track-like polluted cloud tracks provide a direct way to study aerosol-cloud interactions. Here, we study environmental conditions favorable for pollution tracks' formation. We study polluted cloud tracks forming downwind of localized anthropogenic air pollution hot spots of Norilsk and Cherepovets in Russia and Thompson in Canada. Polluted cloud tracks form on 20%–37% of days with liquid-phase clouds. The large-scale atmospheric circulation largely determines the occurrence of track-favoring conditions. Tracks tend to form in clean and thin clouds under stable and dry conditions that are more often associated with anticyclonic large-scale flow in the studied locations.

  • Journal article
    Chen L-J, Halekas J, Wang S, DiBraccio GA, Romanelli N, Ng J, Russell CT, Schwartz SJ, Sibeck DG, Farrell W, Pollock C, Gershman D, Giles B, Collado-Vega YMet al., 2022,

    Solitary Magnetic Structures Developed From Gyro-Resonance With Solar Wind Ions at Mars and Earth

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 49, ISSN: 0094-8276
  • Journal article
    Tinoco-Arenas A, Kajdic P, Preisser L, Blanco-Cano X, Trotta D, Burgess Det al., 2022,

    Parametric Study of Magnetosheath Jets in 2D Local Hybrid Simulations

    , FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, Vol: 9, ISSN: 2296-987X
  • Journal article
    Getachew T, McComas DJ, Joyce CJ, Palmerio E, Christian ER, Cohen CMS, Desai M, Giacalone J, Hill ME, Matthaeus WH, McNutt RL, Mitchell DG, Mitchell JG, Rankin JS, Roelof EC, Schwadron NA, Szalay JR, Zank GP, Zhao L-L, Lynch BJ, Phan TD, Bale SD, Whittlesey PL, Kasper JCet al., 2022,

    PSP/IS circle dot IS Observation of a Solar Energetic Particle Event Associated with a Streamer Blowout Coronal Mass Ejection during Encounter 6

    , ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X
  • Journal article
    Bandyopadhyay R, Matthaeus WH, McComas DJ, Chhiber R, Usmanov A, Huang J, Livi R, Larson DE, Kasper JC, Case AW, Stevens M, Whittlesey P, Romeo OM, Bale SD, Bonnell JW, de Wit TD, Goetz K, Harvey PR, MacDowall RJ, Malaspina DM, Pulupa Met al., 2022,

    Sub-Alfvenic Solar Wind Observed by the Parker Solar Probe: Characterization of Turbulence, Anisotropy, Intermittency, and Switchback

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
  • Journal article
    van der Holst B, Huang J, Sachdeva N, Kasper JC, Manchester WB, Borovikov D, Chandran BDG, Case AW, Korreck KE, Larson D, Livi R, Stevens M, Whittlesey P, Bale SD, Pulupa M, Malaspina DM, Bonnell JW, Harvey PR, Goetz K, MacDowall RJet al., 2022,

    Improving the Alfven Wave Solar Atmosphere Model Based on Parker Solar Probe Data

    , ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X
  • Journal article
    Mostafavi P, Allen RC, McManus MD, Ho GC, Raouafi NE, Larson DE, Kasper JC, Bale SDet al., 2022,

    Alpha-Proton Differential Flow of the Young Solar Wind: Parker Solar Probe Observations

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
  • Journal article
    Zank GP, Zhao L-L, Adhikari L, Telloni D, Kasper JC, Stevens M, Rahmati A, Bale SDet al., 2022,

    Turbulence in the Sub-Alfvenic Solar Wind

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
  • Journal article
    Vasko IY, Alimov K, Phan T, Bale SD, Mozer FS, Artemyev Aet al., 2022,

    Kinetic-scale Current Sheets in the Solar Wind at 1 au: Scale-dependent Properties and Critical Current Density

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
  • Journal article
    Shi C, Zhao J, Malaspina DM, Bale SD, Dong X, Wang T, Wu Det al., 2022,

    Multiband Electrostatic Waves below and above the Electron Cyclotron Frequency in the Near-Sun Solar Wind

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
  • Journal article
    Rodriguez L, Barnes D, Hosteaux S, Davies JA, Willems S, Pant V, Harrison RA, Berghmans D, Bothmer V, Eastwood JP, Gallagher PT, Kilpua EKJ, Magdalenic J, Mierla M, Mostl C, Rouillard AP, Odstrcil D, Poedts Set al., 2022,

    Comparing the heliospheric cataloging, analysis, and techniques service (HELCATS) manual and automatic catalogues of coronal mass ejections using solar terrestrial relations observatory/heliospheric Imager (STEREO/HI) Data

    , Solar Physics: a journal for solar and solar-stellar research and the study of solar terrestrial physics, Vol: 297, ISSN: 0038-0938

    We present the results of a comparative study between automatic and manually compiled coronal mass ejection (CME) catalogues based on observations from the Heliospheric Imagers (HIs) onboard NASA’s Solar Terrestrial Relations Observatory (STEREO) spacecraft. Using the Computer Aided CME Tracking software (CACTus), CMEs are identified in HI data using an automatic feature-detection algorithm, while the Heliospheric Imagers Catalogue (HICAT) includes CMEs that are detected by visual inspection of HI images. Both catalogues were compiled as part of the EU FP7 Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project (www.helcats-fp7.eu). We compare observational parameters of the CMEs from CACTus to those listed in HICAT, such as CME frequency, position angle (PA), and PA-width. We also compare CACTus-derived speeds to speeds derived from applying geometric modelling to the majority of the HICAT CMEs, the results of which are listed in the HELCATS Heliospheric Imagers Geometric Catalogue (HIGeoCAT). We find that both CACTus and HICAT catalogues contain a similar number of events when we exclude events narrower than 20∘, which are not included in the HICAT catalogue but are found to be identified by CACTus. PA-distributions are strongly peaked around 90∘ and 270∘, with a slightly larger CME frequency northwards of the equatorial plane (particularly for the STEREO-A versions of both catalogues). The CME PA-widths in both HICAT and CACTus catalogues peak at approximately 60∘. Manually derived speeds from HIGeoCAT and automatically derived speeds by CACTus correlate well for values lower than 1000 km s−1, in particular when CMEs are propagating close to the plane of the sky.

  • Journal article
    Shebanits O, Wahlund J-E, Waite JH, Dougherty MKet al., 2022,

    Conductivities of Titan's Dusty Ionosphere

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380
  • Journal article
    Archer M, Southwood D, Hartinger M, Rastaetter L, Wright Aet al., 2022,

    How a realistic magnetosphere alters the polarizations of surface, fast magnetosonic, and Alfvén waves

    , Journal of Geophysical Research: Space Physics, Vol: 127, ISSN: 2169-9380

    System-scale magnetohydrodynamic (MHD) waves within Earth's magnetosphere are often understood theoretically using box models. While these have been highly instructive in understanding many fundamental features of the various wave modes present, they neglect the complexities of geospace such as the inhomogeneities and curvilinear geometries present. Here, we show global MHD simulations of resonant waves impulsively excited by a solar wind pressure pulse. Although many aspects of the surface, fast magnetosonic (cavity/waveguide), and Alfvén modes present agree with the box and axially symmetric dipole models, we find some predictions for large-scale waves are significantly altered in a realistic magnetosphere. The radial ordering of fast mode turning points and Alfvén resonant locations may be reversed even with monotonic wave speeds. Additional nodes along field lines that are not present in the displacement/velocity occur in both the perpendicular and compressional components of the magnetic field. Close to the magnetopause, the perpendicular oscillations of the magnetic field have the opposite handedness to the velocity. Finally, widely used detection techniques for standing waves, both across and along the field, can fail to identify their presence. We explain how all these features arise from the MHD equations when accounting for a non-uniform background field and propose modified methods that might be applied to spacecraft observations.

  • Journal article
    Mozer FS, Bale SD, Kellogg PJ, Larson D, Livi R, Romeo Oet al., 2022,

    An Improved Technique for Measuring Plasma Density to High Frequencies on the Parker Solar Probe

    , ASTROPHYSICAL JOURNAL, Vol: 926, ISSN: 0004-637X
  • Journal article
    Lario D, Richardson IG, Wilson III LB, Berger L, Jian LK, Trotta Det al., 2022,

    The Extended Field-aligned Suprathermal Proton Beam and Long-lasting Trapped Energetic Particle Population Observed Upstream of a Transient Interplanetary Shock

    , ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X
  • Journal article
    Agapitov V, Drake JF, Swisdak M, Bale SD, Horbury TS, Kasper JC, MacDowall RJ, Mozer FS, Phan TD, Pulupa M, Raouafi E, Velli Met al., 2022,

    Flux Rope Merging and the Structure of Switchbacks in the Solar Wind

    , ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X
  • Journal article
    Simon Wedlund CL, Volwerk M, Beth A, Mazelle C, Moestl C, Halekas JS, Gruesbeck JR, Rojas-Castillo Det al., 2022,

    A fast bow shock location predictor-estimator from 2D and 3D analytical models: Application to Mars and the MAVEN mission

    , Journal of Geophysical Research: Space Physics, ISSN: 2169-9380
  • Journal article
    Christensen MW, Gettelman A, Cermak J, Dagan G, Diamond M, Douglas A, Feingold G, Glassmeier F, Goren T, Grosvenor DP, Gryspeerdt E, Kahn R, Li Z, Ma P-L, Malavelle F, McCoy IL, McCoy DT, McFarquhar G, Mulmenstadt J, Pal S, Possner A, Povey A, Quaas J, Rosenfeld D, Schmidt A, Schroedner R, Sorooshian A, Stier P, Toll V, Watson-Parris D, Wood R, Yang M, Yuan Tet al., 2022,

    Opportunistic experiments to constrain aerosol effective radiative forcing

    , Atmospheric Chemistry and Physics, Vol: 22, Pages: 641-674, ISSN: 1680-7316

    Aerosol–cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be challenging when meteorological variability also drives both aerosol and cloud changes independently. Natural and anthropogenic aerosol perturbations from well-defined sources provide “opportunistic experiments” (also known as natural experiments) to investigate ACI in cases where causality may be more confidently inferred. These perturbations cover a wide range of locations and spatiotemporal scales, including point sources such as volcanic eruptions or industrial sources, plumes from biomass burning or forest fires, and tracks from individual ships or shipping corridors. We review the different experimental conditions and conduct a synthesis of the available satellite datasets and field campaigns to place these opportunistic experiments on a common footing, facilitating new insights and a clearer understanding of key uncertainties in aerosol radiative forcing. Cloud albedo perturbations are strongly sensitive to background meteorological conditions. Strong liquid water path increases due to aerosol perturbations are largely ruled out by averaging across experiments. Opportunistic experiments have significantly improved process-level understanding of ACI, but it remains unclear how reliably the relationships found can be scaled to the global level, thus demonstrating a need for deeper investigation in order to improve assessments of aerosol radiative forcing and climate change.

  • Journal article
    Chadney JM, Koskinen TT, Hu X, Galand M, Lavvas P, Unruh Y, Serigano J, Hörst SM, Yelle RVet al., 2022,

    Energy deposition in Saturn's equatorial upper atmosphere

    , Icarus, Vol: 372, Pages: 1-16, ISSN: 0019-1035

    We construct Saturn equatorial neutral temperature and density profiles of H, H2, He, and CH4, between 10−12 and 1 bar using measurements from Cassini’s Ion Neutral Mass Spectrometer (INMS) taken during the spacecraft’s final plunge into Saturn’s atmosphere on 15 September 2017, combined with previous deeper atmospheric measurements from the Cassini Composite InfraRed Spectrometer (CIRS) and from the UltraViolet Imaging Spectrograph (UVIS). These neutral profiles are fed into an energy deposition model employing soft X-ray and Extreme UltraViolet (EUV) solar fluxes at a range of spectral resolutions (∆λ = 4×10−3 nm to 1 nm) assembled from TIMED/SEE, from SOHO/SUMER, and from the Whole Heliosphere Interval (WHI) quiet Sun campaign. Our energy deposition model calculates ion production rate profiles through photo-ionisation and electron-impact ionisation processes, as well as rates of photo-dissociation of CH4. The ion reaction rate profiles we determine are important to obtain accurate ion density profiles, meanwhile methane photo-dissociation is key to initiate complex organic chemical processes. We assess the importance of spectral resolution in the energy deposition model by using a high-resolution H2 photo-absorption cross section, which has the effect of producing additional ionisation peaks near 800 km altitude. We find that these peaks are still formed when using low resolution (∆λ = 1 nm) or mid-resolution (∆λ = 0.1 nm) solar spectra, as long as high-resolution cross sections are included in the model.

  • Journal article
    Rodriguez S, Vinatier S, Cordier D, Tobie G, Achterberg RK, Anderson CM, Badman SV, Barnes JW, Barth EL, Bézard B, Carrasco N, Charnay B, Clark RN, Coll P, Cornet T, Coustenis A, Couturier-Tamburelli I, Dobrijevic M, Flasar FM, Kok RD, Freissinet C, Galand M, Gautier T, Geppert WD, Griffith CA, Gudipati MS, Hadid LZ, Hayes AG, Hendrix AR, Jauman R, Jennings DE, Jolly A, Kalousova K, Koskinen TT, Lavvas P, Lebonnois S, Lebreton J-P, Gall AL, Lellouch E, Mouélic SL, Lopes RMC, Lora JM, Lorenz RD, Lucas A, MacKenzie S, Malaska MJ, Mandt K, Mastrogiuseppe M, Newman CE, Nixon CA, Radebaugh J, Rafkin SC, Rannou P, Sciamma-O-Brien EM, Soderblom JM, Solomonidou A, Sotin C, Stephan K, Strobel D, Szopa C, Teanby NA, Turtle EP, Vuitton V, West RAet al., 2022,

    Science goals and new mission concepts for future exploration of Titan's atmosphere geology and habitability: Titan POlar Scout/orbitEr and In situ lake lander and DrONe explorer (POSEIDON)

    , Experimental Astronomy: an international journal on astronomical instrumentation and data analysis, ISSN: 0922-6435

    In response to ESA’s “Voyage 2050” announcement of opportunity, we propose an ambitious L-class mission to explore one of the most exciting bodies in the Solar System, Saturn’s largest moon Titan. Titan, a “world with two oceans”, is an organic-rich body with interior-surface-atmosphere interactions that are comparable in complexity to the Earth. Titan is also one of the few places in the Solar System with habitability potential. Titan’s remarkable nature was only partly revealed by the Cassini-Huygens mission and still holds mysteries requiring a complete exploration using a variety of vehicles and instruments. The proposed mission concept POSEIDON (Titan POlar Scout/orbitEr and In situ lake lander DrONe explorer) would perform joint orbital and in situ investigations of Titan. It is designed to build on and exceed the scope and scientific/technological accomplishments of Cassini-Huygens, exploring Titan in ways that were not previously possible, in particular through full close-up and in situ coverage over long periods of time. In the proposed mission architecture, POSEIDON consists of two major elements: a spacecraft with a large set of instruments that would orbit Titan, preferably in a low-eccentricity polar orbit, and a suite of in situ investigation components, i.e. a lake lander, a “heavy” drone (possibly amphibious) and/or a fleet of mini-drones, dedicated to the exploration of the polar regions. The ideal arrival time at Titan would be slightly before the next northern Spring equinox (2039), as equinoxes are the most active periods to monitor still largely unknown atmospheric and surface seasonal changes. The exploration of Titan’s northern latitudes with an orbiter and in situ element(s) would be highly complementary in terms of timing (with possible mission timing overlap), locations, and science goals with the upcoming NASA New Frontiers Dragonfly mission that will provide in situ exploration o

  • Journal article
    Stawarz J, Eastwood J, Phan T, Gingell I, Pyakurel P, Shay M, Robertson S, Russell C, Le Contel Oet al., 2022,

    Turbulence-driven magnetic reconnection and the magnetic correlation length: observations from magnetospheric multiscale in Earth's magnetosheath

    , Physics of Plasmas, Vol: 29, Pages: 1-20, ISSN: 1070-664X

    Turbulent plasmas generate a multitude of thin current structures that can be sites for magnetic reconnection. The Magnetospheric Multiscale (MMS) mission has recently enabled the detailed examination of such turbulent current structures in Earth's magnetosheath and revealed that a novel type of reconnection, known as electron-only reconnection, can occur. In electron-only reconnection, ions do not have enough space to couple to the newly reconnected magnetic fields, suppressing ion jet formation and resulting in thinner sub-proton-scale current structures with faster super-Alfvénic electron jets. In this study, MMS observations are used to examine how the magnetic correlation length (λC) of the turbulence, which characterizes the size of the large-scale magnetic structures and constrains the length of the current sheets formed, influences the nature of turbulence-driven reconnection. We systematically identify 256 reconnection events across 60 intervals of magnetosheath turbulence. Most events do not appear to have ion jets; however, 18 events are identified with ion jets that are at least partially coupled to the reconnected magnetic field. The current sheet thickness and electron jet speed have a weak anti-correlation, with faster electron jets at thinner current sheets. When 𝜆𝐶≲20 ion inertial lengths, as is typical near the sub-solar magnetosheath, a tendency for thinner current sheets and potentially faster electron jets is present. The results are consistent with electron-only reconnection being more prevalent for turbulent plasmas with relatively short λC and may be relevant to the nonlinear dynamics and energy dissipation in turbulent plasmas.

  • Journal article
    Heyns MJ, Lotz SI, Cilliers PJ, Gaunt CTet al., 2022,

    Adaptations to a geomagnetic field interpolation method in Southern Africa

    , Advances in Space Research, ISSN: 0273-1177

    Space weather and its impact on infrastructure presents a clear risk in the modern era, as evidenced by the adverse effects of geomagnetically induced currents (GICs) in power networks. To model GICs, ground-based geomagnetic field (B-field) measurements are critical and need to be available in the region of interest. A challenge globally lies in the sparse distribution of magnetometer arrays, which are seldom located near critical power network nodes. Interpolation of the geomagnetic field (B-field) is often needed, with the spherical elementary current system (SECS) approach developed for high-latitude regions favoured. We adapt this interpolation scheme to include low-cost variometers to interpolate dB/dt directly and increase interpolation accuracy. A further adaptation to the scheme is to physically represent the mid-latitude context where most power networks and pipelines lie. The driving current systems in these regions differ from their high-latitude counterparts. Using a physics-consistent mid-latitude version of SECS, we show why previous implementations in Southern Africa are incorrect but still result in useful interpolation. The scope of these adaptations not only has direct application to research in general, but also to utilities, where effective low-cost instrumentation can be used to improve GIC modelling accuracy.

  • Conference paper
    Angelini V, O'Brien H, Horbury T, Fauchon-Jones Eet al., 2022,

    Novel magnetic cleaning techniques for Solar Orbiter magnetometer

    Solar Orbiter is an ESA mission studying the heliosphere and the Sun. The magnetometer is designed to measure the magnetic field local to the spacecraft and is composed of two sensors located on a boom at different displacement from the spacecraft. This configuration reduces the electromagnetic interference caused by other on-board electrical systems and allows the exploitation of the 'gradiometer technique' to separate spacecraft generated signals from the solar magnetic field. This paper describes the analysis of the magnetometer data to develop a completely novel procedure for removing the magnetic field generated by the spacecraft-controlled heaters, the instruments, and the thrusters on the spacecraft. The difference between the data measured by the two sensors is used to identify this signal, which is then appropriately scaled and removed from the data. This approach produces cleaned magnetic field data which is routinely uploaded to the Solar Orbiter Archive for science exploitation.

  • Journal article
    Verniero JL, Chandran BDG, Larson DE, Paulson K, Alterman BL, Badman S, Bale SD, Bonnell JW, Bowen TA, de Wit TD, Kasper JC, Klein KG, Lichko E, Livi R, McManus MD, Rahmati A, Verscharen D, Walters J, Whittlesey PLet al., 2022,

    Strong Perpendicular Velocity-space Diffusion in Proton Beams Observed by Parker Solar Probe

    , ASTROPHYSICAL JOURNAL, Vol: 924, ISSN: 0004-637X

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://www.imperial.ac.uk:80/respub/WEB-INF/jsp/search-t4-html.jsp Request URI: /respub/WEB-INF/jsp/search-t4-html.jsp Query String: id=214&limit=30&page=5&respub-action=search.html Current Millis: 1675091226559 Current Time: Mon Jan 30 15:07:06 GMT 2023