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
    Stephenson P, Galand M, Deca J, Henri Pet al., 2024,

    Cold electrons at a weakly outgassing comet

    , Monthly Notices of the Royal Astronomical Society, ISSN: 0035-8711

    <jats:title>Abstract</jats:title> <jats:p>Throughout the Rosetta mission, cold electrons (&amp;lt;1eV) were measured in the coma of comet 67P/Churyumov-Gerasimenko. Cometary electrons are produced at ∼10eV through photoionization or through electron-impact ionization collisions. The cold electron population is formed by cooling the warm population through inelastic electron-neutral collisions. Assuming radial electron outflow, electrons are collisional with the neutral gas coma below the electron exobase, which only formed above the comet surface in near-perihelion, high outgassing conditions (Q &amp;gt; 3 × 1027s−1). However, the cold population was identified at low outgassing (Q &amp;lt; 1026s−1), when the inner coma was not expected to be collisional. We examine cooling of electrons at a weakly outgassing comet, using a 3D collisional model of electrons at a comet. Electron paths are extended by trapping in an ambipolar electric field and by gyration around magnetic field lines. This increases the probability of electrons undergoing inelastic collisions with the coma and becoming cold. We demonstrate that a cold electron population can be formed and sustained, under weak outgassing conditions (Q = 1026s−1), once 3D electron dynamics are accounted for. Cold electrons are produced in the inner coma through electron-neutral collisions and transported tailwards by an E × B drift We quantify the efficiency of trapping in driving electron cooling, with trajectories typically 100 times longer than expected from ballistic radial outflow. Based on collisional simulations, we define an estimate for a region where a cold electron population can form, bounded by an electron cooling exobase. This estimate agrees well with cold electron measurements from the Rosetta Plasma Consortium.</jats:p>

  • Journal article
    Heinemann SG, Sishtla C, Good S, Grandin M, Pomoell Jet al., 2024,

    Classification of Enhanced Geoeffectiveness Resulting from High-speed Solar Wind Streams Compressing Slower Interplanetary Coronal Mass Ejections

    , The Astrophysical Journal Letters, Vol: 963, Pages: L25-L25, ISSN: 2041-8205

    <jats:title>Abstract</jats:title> <jats:p>High-speed solar wind streams (HSSs) interact with the preceding ambient solar wind to form stream interaction regions (SIRs), which are a primary source of recurrent geomagnetic storms. However, HSSs may also encounter and subsequently interact with interplanetary coronal mass ejections (ICMEs). In particular, the impact of the interaction between slower ICMEs and faster HSSs represents an unexplored area that requires further in-depth investigation. This specific interaction can give rise to unexpected geomagnetic storm signatures, diverging from the conventional expectations of individual SIR events sharing similar HSS properties. Our study presents a comprehensive analysis of solar wind data spanning from 1996 to 2020, capturing 23 instances where such encounters led to geomagnetic storms (<jats:italic>SymH</jats:italic> &lt; −30 nT). We determined that interaction events between preceding slower ICMEs and faster HSSs possess the potential to induce substantial storm activity, statistically nearly doubling the geoeffective impact in comparison to SIR storm events. The increase in the amplitude of the <jats:italic>SymH</jats:italic> index appears to result from heightened dynamic pressure, often coupled with the concurrent amplification of the CMEs rearward ∣<jats:italic>B</jats:italic>∣ and/or <jats:italic>B</jats:italic> <jats:sub> <jats:italic>z</jats:italic> </jats:sub> components.</jats:p>

  • Journal article
    Matteini L, Tenerani A, Landi S, Verdini A, Velli M, Hellinger P, Franci L, Horbury TS, Papini E, Stawarz JEet al., 2024,

    Alfvénic fluctuations in the expanding solar wind: Formation and radial evolution of spherical polarization

    , Physics of Plasmas, Vol: 31, ISSN: 1070-664X

    We investigate properties of large-scale solar wind Alfvénic fluctuations and their evolution during radial expansion. We assume a strictly radial background magnetic field B ∥ R , and we use two-dimensional hybrid (fluid electrons, kinetic ions) simulations of balanced Alfvénic turbulence in the plane orthogonal to B ; the simulated plasma evolves in a system comoving with the solar wind (i.e., in the expanding box approximation). Despite some model limitations, simulations exhibit important properties observed in the solar wind plasma: Magnetic field fluctuations evolve toward a state with low-amplitude variations in the amplitude B = | B | and tend to a spherical polarization. This is achieved in the plasma by spontaneously generating field aligned, radial fluctuations that suppress local variations of B, maintaining B ∼ const. spatially in the plasma. We show that within the constraint of spherical polarization, variations in the radial component of the magnetic field, BR lead to a simple relation between δ B R and δ B = | δ B | as δ B R ∼ δ B 2 / ( 2 B ) , which correctly describes the observed evolution of the rms of radial fluctuations in the solar wind. During expansion, the background magnetic field amplitude decreases faster than that of fluctuations so that their the relative amplitude increases. In the regime of strong fluctuations, δ B ∼ B , this causes local magnetic field reversals, consistent with solar wind switchbacks.

  • Journal article
    Trotta D, Larosa A, Nicolaou G, Horbury TS, Matteini L, Hietala H, Blanco-Cano X, Franci L, Chen CHK, Zhao L, Zank GP, Cohen CMS, Bale SD, Laker R, Fargette N, Valentini F, Khotyaintsev Y, Kieokaew R, Raouafi N, Davies E, Vainio R, Dresing N, Kilpua E, Karlsson T, Owen CJ, Wimmer-Schweingruber RFet al., 2024,

    Properties of an Interplanetary Shock Observed at 0.07 and 0.7 au by Parker Solar Probe and Solar Orbiter

    , The Astrophysical Journal, Vol: 962, Pages: 147-147, ISSN: 0004-637X

    <jats:title>Abstract</jats:title> <jats:p>The Parker Solar Probe (PSP) and Solar Orbiter (SolO) missions opened a new observational window in the inner heliosphere, which is finally accessible to direct measurements. On 2022 September 5, a coronal mass ejection (CME)-driven interplanetary (IP) shock was observed as close as 0.07 au by PSP. The CME then reached SolO, which was radially well-aligned at 0.7 au, thus providing us with the opportunity to study the shock properties at different heliocentric distances. We characterize the shock, investigate its typical parameters, and compare its small-scale features at both locations. Using the PSP observations, we investigate how magnetic switchbacks and ion cyclotron waves are processed upon shock crossing. We find that switchbacks preserve their V–B correlation while compressed upon the shock passage, and that the signature of ion cyclotron waves disappears downstream of the shock. By contrast, the SolO observations reveal a very structured shock transition, with a population of shock-accelerated protons of up to about 2 MeV, showing irregularities in the shock downstream, which we correlate with solar wind structures propagating across the shock. At SolO, we also report the presence of low-energy (∼100 eV) electrons scattering due to upstream shocklets. This study elucidates how the local features of IP shocks and their environments can be very different as they propagate through the heliosphere.</jats:p>

  • Journal article
    Louarn P, Fedorov A, Prech L, Owen CJ, D'Amicis R, Bruno R, Livi S, Lavraud B, Rouillard AP, Génot V, André N, Fruit G, Réville V, Kieokaew R, Plotnikov I, Penou E, Barthe A, Lewis G, Berthomier M, Allegrini F, Alterman BL, Lepri ST, Raines JM, Verscharen D, Mele G, Fargette N, Horbury TS, Maksimovic M, Kasper JC, Bale SDet al., 2024,

    Skewness and kurtosis of solar wind proton distribution functions: The normal inverse-Gaussian model and its implications

    , Astronomy and Astrophysics, Vol: 682, ISSN: 0004-6361

    Context. In the solar wind (SW), the particle distribution functions are generally not Gaussian. They present nonthermal features that are related to underlying acceleration and heating processes. These processes are critical in the overall dynamics of this expanding astrophysical fluid. Aims. The Proton Alpha Sensor (PAS) on board Solar Orbiter commonly observes skewed proton distributions, with a more populated high-energy side in the magnetic field direction than the Gaussian distribution. Our objectives are: (1) to identify a theoretical statistical function that adequately models the observed distributions and (2) to use its statistical interpretation to constrain the acceleration and heating processes. Methods. We analyzed the 3D velocity distribution functions (VDFs) measured by PAS and compared them to model statistical functions. Results. We show that the normal inverse Gaussian (NIG), a type of hyperbolic statistical distribution, provides excellent fits of skewed and leptokurtic proton distributions. NIG can model both the core distribution and the beam, if present. We propose an interpretation that is inspired by the mathematical formulation of the NIG. It assumes that the acceleration or heating mechanism can be modeled as a drifting diffusion process in velocity space, controlled (or subordinated) by the time of interaction of the particles with "accelerating structures". The probability function of the interaction time is an inverse Gaussian (IG), obtained by considering a random drift across structures of a given size. The control of the diffusion by interaction times that follow an IG probability function formally defines the NIG distribution. Following this model, we show that skewness and kurtosis can be used to estimate the kinetic and thermal energy gains provided by the interaction with structures. For example, in the case studies presented here, the analyzed populations would have gained kinetic energy representing approximately two

  • Journal article
    Laker R, Horbury TS, OBrien H, Fauchon-Jones EJ, Angelini V, Fargette N, Amerstorfer T, Bauer M, Möstl C, Davies EE, Davies JA, Harrison R, Barnes D, Dumbović Met al., 2024,

    Using Solar Orbiter as an Upstream Solar Wind Monitor for Real Time Space Weather Predictions

    , Space Weather, Vol: 22

    Coronal mass ejections (CMEs) can create significant disruption to human activities and systems on Earth, much of which can be mitigated with prior warning of the upstream solar wind conditions. However, it is currently extremely challenging to accurately predict the arrival time and internal structure of a CME from coronagraph images alone. In this study, we take advantage of a rare opportunity to use Solar Orbiter, at 0.5 au upstream of Earth, as an upstream solar wind monitor. In combination with low-latency images from STEREO-A, we successfully predicted the arrival time of two CME events before they reached Earth. Measurements at Solar Orbiter were used to constrain an ensemble of simulation runs from the ELEvoHI model, reducing the uncertainty in arrival time from 10.4 to 2.5 hr in the first case study. There was also an excellent agreement in the Bz profile between Solar Orbiter and Wind spacecraft for the second case study, despite being separated by 0.5 au and 10° longitude. The opportunity to use Solar Orbiter as an upstream solar wind monitor will repeat once a year, which should further help assess the efficacy upstream in-situ measurements in real time space weather forecasting.

  • Journal article
    Laker R, Horbury TS, Woodham LD, Bale SD, Matteini Let al., 2024,

    Coherent deflection patternãndãssociated temperature enhancements in the near-Sun solar wind

    , Monthly Notices of the Royal Astronomical Society, Vol: 527, Pages: 10440-10447, ISSN: 0035-8711

    Measurements of transverse magnetic fieldãnd velocity components from Parker Solar Probe hav e rev ealedã coherent quasi- periodic pattern in the near-Sun solar wind. As wellãs being Alfvénicãndãrc-polarized, these deflections were characterized byã consistent orientationãndãn increased proton core temperature, which was greater parallel to the magnetic field. We show that switchbacks represent the largest deflections within this underlying structure, which is itself consistent with the expected outflow from interchange reconnection simulations. Additionally, the spatial scale of the deflections was estimated to beãround 1 Mm on the Sun, comparable to the jettingãctivity observedãt coronal bright points within the base of coronal plumes. Therefore, our results could represent the in situ signature of interchange reconnection from coronal bright points within plumes, complementing recent numericalãnd observational studies. Weãlso foundã consistent relationship between the proton core temperatureãnd magnetic fieldãngleãcross the Parker Solar Probe encountersãnd discussed how suchã persistent signature could be more indicative ofãn in situ mechanism creatingã local increase in temperature. In future, observations of minor ions, radio bursts,ãnd remote sensing images could help further establish the connection between reconnection events on the Sunãnd signatures in the solar wind.

  • Journal article
    Mostafavi P, Allen RC, Jagarlamudi VK, Bourouaine S, Badman ST, Ho GC, Raouafi NE, Hill ME, Verniero JL, Larson DE, Kasper JC, Bale SDet al., 2024,

    Parker Solar Probe observations of collisional effects on thermalizing the young solar wind

    , Astronomy and Astrophysics, Vol: 682, ISSN: 0004-6361

    Solar wind ions exhibit distinct kinetic non-thermal features such as preferential heating and acceleration of alpha particles compared to protons. On the other hand, Coulomb collisions in the solar wind act to eliminate these non-thermal features and gradually lead to thermal equilibrium. Previous observations at 1 au have revealed that even though the local Coulomb collisions in the solar wind plasma are rare, the cumulative effect of the collisions during a transit time of a particle can be important in terms of thermalizing the solar wind plasma populations and reducing the ion non-thermal features. Here, we analyze Parker Solar Probe observations to study the effects of Coulomb collisions on the non-thermal features (alpha-to-proton temperature ratio and differential flow) of young solar wind closer to the Sun than previously possible. Our results show that even close to the Sun (~15Rs), these non-thermal features are organized by collisionality. Moreover, observations at these unprecedented distances allow us to investigate the preferential heating of the alpha particles close to the source for both fast and slow wind streams. We show that the alpha-to-proton temperature ratio is positively correlated with the solar wind speed, which is consistent with Wind observations. Solar wind close to the Sun is less collisionally old than when it reaches 1 au. As such, observed differences in the temperature ratio between slow and fast streams near their solar source suggest causes that go beyond different Coulomb numbers. Our results suggest that slow and fast wind streams, originating from different solar regions, may have different mechanisms for the preferential heating of alpha particles compared to protons.

  • Journal article
    Wells CD, Kasoar M, Ezzati M, Voulgarakis Aet al., 2024,

    Significant human health co-benefits of mitigating African emissions

    , Atmospheric Chemistry and Physics, Vol: 24, Pages: 1025-1039, ISSN: 1680-7316

    Future African aerosol emissions, and therefore air pollution levels and health outcomes, are uncertain and understudied. Understanding the future health impacts of pollutant emissions from this region is crucial. Here, this research gap is addressed by studying the range in the future health impacts of aerosol emissions from Africa in the Shared Socioeconomic Pathway (SSP) scenarios, using the UK Earth System Model version 1 (UKESM1), along with human health concentration-response functions. The effects of Africa following a high-pollution aerosol pathway are studied relative to a low-pollution control, with experiments varying aerosol emissions from industry and biomass burning. Using present-day demographics, annual deaths within Africa attributable to ambient particulate matter are estimated to be lower by 150 000 (5th-95th confidence interval of 67 000-234 000) under stronger African aerosol mitigation by 2090, while those attributable to O3 are lower by 15 000 (5th-95th confidence interval of 9000-21 000). The particulate matter health benefits are realised predominantly within Africa, with the O3-driven benefits being more widespread - though still concentrated in Africa - due to the longer atmospheric lifetime of O3. These results demonstrate the important health co-benefits from future emission mitigation in Africa.

  • Journal article
    Krupar V, Kruparova O, Szabo A, Nemec F, Maksimovic M, Martinez Oliveros JC, Lario D, Bonnin X, Vecchio A, Pulupa M, Bale SDet al., 2024,

    Comparative Analysis of Type III Radio Bursts and Solar Flares: Spatial Localization and Correlation with Solar Flare Intensity

    , Astrophysical Journal, Vol: 961, ISSN: 0004-637X

    We present a comprehensive study of type III radio bursts and their association with solar flares of magnitude M1.0 and larger, as observed by four widely separated spacecraft (Parker Solar Probe, Solar Orbiter, STEREO-A, and Wind). Our main focus is the introduction and validation of two methods for localizing radio bursts using the available multispacecraft data. The first method utilizes intensity fitting with a circular Gaussian distribution, while the second method is based on the time arrival of radio bursts. We demonstrate the effectiveness of these methods through the analysis of a single type III burst event and compare their results with the traditional radio triangulation technique. Furthermore, we conduct a statistical study of 17 type III bursts associated with M- and X-class solar flares in years 2020-2022. Our findings suggest a possible correlation between solar flare intensities and longitudes, with east limb flares tending to be weaker than west limb flares. We also observe a systematic drift of radio burst longitudes toward the east, potentially explained by a poleward component of the local density gradient. Our results suggest a strong correlation between solar flare intensities and radio burst properties, enhancing our understanding of the relationship between solar flares and type III radio bursts.

  • Journal article
    Bowen TA, Bale SD, Chandran BDG, Chasapis A, Chen CHK, Dudok de Wit T, Mallet A, Meyrand R, Squire Jet al., 2024,

    Mediation of collisionless turbulent dissipation through cyclotron resonance

    , Nature Astronomy

    The dissipation of turbulence in astrophysical systems is fundamental to energy transfer and heating in environments ranging from the solar wind and corona to accretion disks and the intracluster medium. Although turbulent dissipation is relatively well understood in fluid dynamics, astrophysical plasmas often exhibit exotic behaviour, arising from the lack of interparticle collisions, which complicates turbulent dissipation and heating in these systems. Recent observations by NASA’s Parker Solar Probe mission in the inner heliosphere have shed new light on the role of ion cyclotron resonance as a potential candidate for turbulent dissipation and plasma heating. Here, using in situ observations of turbulence and wave populations, we show that ion cyclotron waves provide a major pathway for dissipation and plasma heating in the solar wind. Our results support recent theoretical predictions of turbulence in the inner heliosphere, known as the helicity barrier, that suggest a role of cyclotron resonance in ion-scale dissipation. Taken together, these results provide important constraints for turbulent dissipation and acceleration efficiency in astrophysical plasmas.

  • Journal article
    Chen L, Ma B, Wu DJ, Zhou X, Pulupa M, Zhang PJ, Zucca P, Bale SD, Kasper JC, Duan SPet al., 2024,

    Weak Solar Radio Bursts from the Solar Wind Acceleration Region Observed by the Parker Solar Probe and Its Probable Emission Mechanism

    , Astrophysical Journal, Vol: 961, ISSN: 0004-637X

    The Parker Solar Probe (PSP) provides us with an unprecedentedly close approach to the observation of the Sun and hence the possibility of directly understanding the elementary process that occurs on the kinetic scale of particles' collective interaction in solar coronal plasmas. We report a type of weak solar radio burst (SRB) that was detected by PSP when it passed a low-density magnetic channel during its second encounter phase. These weak SRBs have a low starting frequency of ∼20 MHz and a narrow frequency range from a few tens of MHz to a few hundred kHz. Their dynamic spectra display a strongly evolving feature of the intermediate relative drift rate decreasing rapidly from above 0.01 s−1 to below 0.01 s−1. Analyses based on common empirical models of solar coronal plasmas indicate that these weak SRBs originate from a heliocentric distance of ∼1.1-6.1 R S (the solar radius), a typical solar wind acceleration region with a low-β plasma, and that their sources have a typical motion velocity of ∼v A (Alfvén velocity) obviously lower than that of the fast electrons required to effectively excite SRBs. We propose that solitary kinetic Alfvén waves with kinetic scales could be responsible for the generation of these small-scale weak SRBs, called solitary wave radiation.

  • Journal article
    McManus MD, Klein KG, Bale SD, Bowen TA, Huang J, Larson D, Livi R, Rahmati A, Romeo O, Verniero J, Whittlesey Pet al., 2024,

    Proton- and Alpha-driven Instabilities in an Ion Cyclotron Wave Event

    , Astrophysical Journal, Vol: 961, ISSN: 0004-637X

    Ion-scale wave events or wave storms in the solar wind are characterized by enhancements in magnetic field fluctuations as well as coherent magnetic field polarization signatures at or around the local ion cyclotron frequencies. In this paper, we study in detail one such wave event from Parker Solar Probe's (PSP) fourth encounter, consisting of an initial period of left-handed (LH) polarization abruptly transitioning to a strong period of right-handed (RH) polarization, accompanied by a clear core beam structure in both the alpha and proton velocity distribution functions. A linear stability analysis shows that the LH-polarized waves are anti-sunward propagating Alfvén/ion cyclotron waves primarily driven by a proton cyclotron instability in the proton core population, and the RH polarized waves are anti-sunward propagating fast magnetosonic/whistler waves driven by a firehose-like instability in the secondary alpha beam population. The abrupt transition from LH to RH is caused by a drop in the proton core temperature anisotropy. We find very good agreement between the frequencies and polarizations of the unstable wave modes as predicted by linear theory and those observed in the magnetic field spectra. Given the ubiquity of ion-scale wave signatures observed by PSP, this work gives insight into which exact instabilities may be active and mediating energy transfer in wave-particle interactions in the inner heliosphere, as well as highlighting the role a secondary alpha population may play as a rarely considered source of free energy available for producing wave activity.

  • Journal article
    Smith AW, Rae IJ, Stawarz JE, Sun WJ, Bentley S, Koul Aet al., 2024,

    Automatic Encoding of Unlabeled Two Dimensional Data Enabling Similarity Searches: Electron Diffusion Regions and Auroral Arcs

    , Journal of Geophysical Research: Space Physics, Vol: 129, ISSN: 2169-9380

    Critically important phenomena in Earth’s magnetosphere often occur briefly, or in small spatial regions. These processes are sampled with orbiting spacecraft or by fixed ground observatories and so rarely appear in data. Identifying such intervals can be an incredibly time consuming task. We apply a novel, powerful method by which two dimensional data can be automatically processed and embeddings created that contain key features of the data. The distance between embedding vectors serves as a measure of similarity. We apply the state-of-the-art method to two example datasets: MMS electron velocity distributions and auroral all sky images. We show that the technique creates embeddings that group together visually similar observations. When provided with novel example images the method correctly identifies similar intervals: when provided with an electron distribution sampled during an encounter with an electron diffusion region the method recovers similar distributions obtained during two other known diffusion region encounters. Similarly, when provided with an interesting auroral structure the method highlights the same structure observed from an adjacent location and at other close time intervals. The method promises to be a useful tool to expand interesting case studies to multiple events, without requiring manual data labeling. Further, the models could be fine-tuned with relatively small set of labeled example data to perform tasks such as classification. The embeddings can also be used as input to deep learning models, providing a key intermediary step—capturing the key features within the data.

  • Journal article
    Hosner M, Nakamura R, Schmid D, Nakamura TKM, Panov EV, Volwerk M, Vörös Z, Roberts OW, Blasl KA, Settino A, Korovinskiy D, Marshall AT, Denton RE, Burch JL, Giles BL, Torbert RB, Le Contel O, Escoubet CP, Dandouras IS, Carr C, Fazakerley ANet al., 2024,

    Reconnection inside a Dipolarization Front of a diverging Earthward fast flow

    , JGR: Space Physics, Vol: 129, ISSN: 2169-9402

    We examine a Dipolarization Front (DF) event with an embedded electron diffusion region (EDR), observed by the Magnetospheric Multiscale (MMS) spacecraft on 08 September 2018 at 14:51:30 UT in the Earth's magnetotail by applying multi-scale multipoint analysis methods. In order to study the large-scale context of this DF, we use conjunction observations of the Cluster spacecraft together with MMS. A polynomial magnetic field reconstruction technique is applied to MMS data to characterize the embedded electron current sheet including its velocity and the X-line exhaust opening angle. Our results show that the MMS and Cluster spacecraft were located in two counter-rotating vortex flows, and such flows may distort a flux tube in a way that the local magnetic shear angle is increased and localized magnetic reconnection may be triggered. Using multi-point data from MMS we further show that the local normalized reconnection rate is in the range of R ∼ 0.16 to 0.18. We find a highly asymmetric electron in- and outflow structure, consistent with previous simulations on strong guide-field reconnection events. This study shows that magnetic reconnection may not only take place at large-scale stable magnetopause or magnetotail current sheets but also in transient localized current sheets, produced as a consequence of the interaction between the fast Earthward flows and the Earth's dipole field.

  • Journal article
    Jones GH, Snodgrass C, Tubiana C, Küppers M, Kawakita H, Lara LM, Agarwal J, André N, Attree N, Auster U, Bagnulo S, Bannister M, Beth A, Bowles N, Coates A, Colangeli L, Corral van Damme C, Da Deppo V, De Keyser J, Della Corte V, Edberg N, El-Maarry MR, Faggi S, Fulle M, Funase R, Galand M, Goetz C, Groussin O, Guilbert-Lepoutre A, Henri P, Kasahara S, Kereszturi A, Kidger M, Knight M, Kokotanekova R, Kolmasova I, Kossacki K, Kührt E, Kwon Y, La Forgia F, Levasseur-Regourd A-C, Lippi M, Longobardo A, Marschall R, Morawski M, Muñoz O, Näsilä A, Nilsson H, Opitom C, Pajusalu M, Pommerol A, Prech L, Rando N, Ratti F, Rothkaehl H, Rotundi A, Rubin M, Sakatani N, Sánchez JP, Simon Wedlund C, Stankov A, Thomas N, Toth I, Villanueva G, Vincent J-B, Volwerk M, Wurz P, Wielders A, Yoshioka K, Aleksiejuk K, Alvarez F, Amoros C, Aslam S, Atamaniuk B, Baran J, Barciński T, Beck T, Behnke T, Berglund M, Bertini I, Bieda M, Binczyk P, Busch M-D, Cacovean A, Capria MT, Carr C, Castro Marín JM, Ceriotti M, Chioetto P, Chuchra-Konrad A, Cocola L, Colin F, Crews C, Cripps V, Cupido E, Dassatti A, Davidsson BJR, De Roche T, Deca J, Del Togno S, Dhooghe F, Donaldson Hanna K, Eriksson A, Fedorov A, Fernández-Valenzuela E, Ferretti S, Floriot J, Frassetto F, Fredriksson J, Garnier P, Gaweł D, Génot V, Gerber T, Glassmeier K-H, Granvik M, Grison B, Gunell H, Hachemi T, Hagen C, Hajra R, Harada Y, Hasiba J, Haslebacher N, Herranz De La Revilla ML, Hestroffer D, Hewagama T, Holt C, Hviid S, Iakubivskyi I, Inno L, Irwin P, Ivanovski S, Jansky J, Jernej I, Jeszenszky H, Jimenéz J, Jorda L, Kama M, Kameda S, Kelley MSP, Klepacki K, Kohout T, Kojima H, Kowalski T, Kuwabara M, Ladno M, Laky G, Lammer H, Lan R, Lavraud B, Lazzarin M, Le Duff O, Lee Q-M, Lesniak C, Lewis Z, Lin Z-Y, Lister T, Lowry S, Magnes W, Markkanen J, Martinez Navajas I, Martins Z, Matsuoka A, Matyjasiak B, Mazelle C, Mazzotta Epifani E, Meier M, Michaelis H, Micheli M, Migliorini A, Millet A-L, Moreno F, Mottola S, Moutounet al., 2024,

    The Comet Interceptor Mission.

    , Space Sci Rev, Vol: 220, ISSN: 0038-6308

    Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA's F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms-1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes - B1, provided by the Japanese space agency, JAXA, and B2 - that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission's science background leading to these objectives, a

  • Journal article
    Quilelli Correa Rocha Ribeiro R, Gryspeerdt E, van Reeuwijk M, 2023,

    Retrieving cloud sensitivity to aerosol using ship emissions in overcast conditions

    , Geophysical Research Letters, Vol: 50, ISSN: 0094-8276

    The interaction between aerosols and clouds is one of the major uncertainties in past climate change, affecting the accuracy of future climate projections. Ship tracks, trails left in clouds through the addition of aerosol in the ship exhaust plume, have become a key observational tool for constraining aerosol-cloud interactions. However, manyexpected tracks remain undetected, presenting a significant gap in current knowledge of aerosol forcing. Here we leverage a plume-parcel model to simulate the impact of aerosol dispersion for 2957 cases off California’s coast on cloud droplet number concentration (CDNC) enhancements. Plume-parcel models show a large sensitivity to updraft uncertainties, which are found to be a primary control on track formation. Using these plume-parcel models, updraft values consistent with observed CDNC enhancements are recovered, suggesting that relying solely on cloud-top radiative cooling may overestimate in-cloud updrafts by around 50%, hence overstating the cloud sensitivity to aerosols.

  • Journal article
    Kuzichev IV, Vasko IY, Artemyev AV, Bale SD, Mozer FSet al., 2023,

    Particle-in-Cell Simulations of Sunward and Anti-sunward Whistler Waves in the Solar Wind

    , Astrophysical Journal, Vol: 959, ISSN: 0004-637X

    We present particle-in-cell simulations of a combined whistler heat flux and temperature anisotropy instability that is potentially operating in the solar wind. The simulations are performed in a uniform plasma and initialized with core and halo electron populations typical of the solar wind beyond about 0.3 au. We demonstrate that the instability produces whistler-mode waves propagating both along (anti-sunward) and opposite (sunward) to the electron heat flux. The saturated amplitudes of both sunward and anti-sunward whistler waves are strongly correlated with their initial linear growth rates, B w / B 0 ∼ ( γ / ω ce ) ν , where for typical electron betas we have 0.6 ≲ ν ≲ 0.9. We show that because of the relatively large spectral width of the whistler waves, the instability saturates through the formation of quasi-linear plateaus around the resonant velocities. The revealed correlations of whistler wave amplitudes and spectral widths with electron beta and temperature anisotropy are consistent with solar wind observations. We show that anti-sunward whistler waves result in an electron heat flux decrease, while sunward whistler waves actually lead to an electron heat flux increase. The net effect is the electron heat flux suppression, whose efficiency is larger for larger electron betas and temperature anisotropies. The electron heat flux suppression can be up to 10%-60% provided that the saturated whistler wave amplitudes exceed about 1% of the background magnetic field. The experimental applications of the presented results are discussed.

  • Journal article
    Sishtla CP, Jebaraj IC, Pomoell J, Magyar N, Pulupa M, Kilpua E, Bale SDet al., 2023,

    The Effect of the Parametric Decay Instability on the Morphology of Coronal Type III Radio Bursts

    , Astrophysical Journal Letters, Vol: 959, ISSN: 2041-8205

    The nonlinear evolution of Alfvén waves in the solar corona leads to the generation of Alfvénic turbulence. This description of the Alfvén waves involves parametric instabilities where the parent wave decays into slow mode waves giving rise to density fluctuations. These density fluctuations, in turn, play a crucial role in the modulation of the dynamic spectrum of type III radio bursts, which are observed at the fundamental of local plasma frequency and are sensitive to the local density. During observations of such radio bursts, fine structures are detected across different temporal ranges. In this study, we examine density fluctuations generated through the parametric decay instability (PDI) of Alfvén waves as a mechanism to generate striations in the dynamic spectrum of type III radio bursts using magnetohydrodynamic simulations of the solar corona. An Alfvén wave is injected into the quiet solar wind by perturbing the transverse magnetic field and velocity components, which subsequently undergo the PDI instability. The type III burst is modeled as a fast-moving radiation source that samples the background solar wind as it propagates to emit radio waves. We find the simulated dynamic spectrum to contain striations directly affected by the multiscale density fluctuations in the wind.

  • Journal article
    Jebaraj IC, Dresing N, Krasnoselskikh V, Agapitov OV, Gieseler J, Trotta D, Wijsen N, Larosa A, Kouloumvakos A, Palmroos C, Dimmock A, Kolhoff A, Kühl P, Fleth S, Fedeli A, Valkila S, Lario D, Khotyaintsev YV, Vainio Ret al., 2023,

    Relativistic electron beams accelerated by an interplanetary shock

    , Astronomy and Astrophysics, Vol: 680, ISSN: 0004-6361

    Context. Collisionless shock waves have long been considered to be among the most prolific particle accelerators in the universe. Shocks alter the plasma they propagate through, and often exhibit complex evolution across multiple scales. Interplanetary (IP) traveling shocks have been recorded in situ for over half a century and act as a natural laboratory for experimentally verifying various aspects of large-scale collisionless shocks. A fundamentally interesting problem in both heliophysics and astrophysics is the acceleration of electrons to relativistic energies (>300 keV) by traveling shocks. Aims. The reason for an incomplete understanding of electron acceleration at IP shocks is due to scale-related challenges and a lack of instrumental capabilities. This Letter presents the first observations of field-aligned beams of relativistic electrons upstream of an IP shock, observed thanks to the instrumental capabilities of Solar Orbiter. This study presents the characteristics of the electron beams close to the source and contributes to the understanding of their acceleration mechanism. Methods. On 25 July 2022, Solar Orbiter encountered an IP shock at 0.98 AU. The shock was associated with an energetic storm particle event, which also featured upstream field-aligned relativistic electron beams observed 14 min prior to the actual shock crossing. The distance of the beam’s origin was investigated using a velocity dispersion analysis (VDA). Peak-intensity energy spectra were anaylzed and compared with those obtained from a semi-analytical fast-Fermi acceleration model. Results. By leveraging Solar Orbiter’s high temporal resolution Energetic Particle Detector (EPD), we successfully showcase an IP shock’s ability to accelerate relativistic electron beams. Our proposed acceleration mechanism offers an explanation for the observed electron beam and its characteristics, while we also explore the potential contributions of more complex mechanisms.

  • Journal article
    Krasnoselskikh V, Zaslavsky A, Artemyev A, Froment C, Dudok de Wit T, Raouafi NE, Agapitov OV, Bale SD, Verniero JLet al., 2023,

    Ion Kinetics of Plasma Interchange Reconnection in the Lower Solar Corona

    , Astrophysical Journal, Vol: 959, ISSN: 0004-637X

    The exploration of the inner heliosphere by the Parker Solar Probe has revealed a highly structured solar wind with ubiquitous deflections from the Parker spiral, known as switchbacks. Interchange reconnection (IR) may play an important role in generating these switchbacks, by forming unstable particle distributions that generate wave activity that in turn may evolve to such structures. IR occurs in very low-beta plasmas and in the presence of strong guiding fields. Although IR is unlikely to release enough energy to provide an important contribution to the heating and acceleration of the solar wind, it affects the way the solar wind is connected to its sources, connecting open field lines to regions of closed fields. This “switching on” provides a mechanism by which the plasma near coronal hole boundaries can mix with that trapped inside the closed loops. This mixing can lead to a new energy balance. It may significantly change the characteristics of the solar wind because this plasma is already preheated and can potentially have quite different density and particle distributions. It not only replenishes the solar wind, but also affects the electric field, which in turn affects the energy balance. This interpenetration is manifested by the formation of a bimodal ion distribution, with a core and a beam-like population. Such distributions are indeed frequently observed by the Parker Solar Probe. Here we provide a first step toward assessing the role of such processes in accelerating and heating the solar wind.

  • Journal article
    Clear CP, Pickering JC, Nave G, Uylings P, Raassen Tet al., 2023,

    Wavelengths and Energy Levels of the Upper Levels of Singly Ionized Nickel (Ni ii) from 3d<sup>8</sup>(<sup>3</sup>F)5f to 3d<sup>8</sup>(<sup>3</sup>F)9s

    , Astrophysical Journal, Supplement Series, Vol: 269, ISSN: 0067-0049

    Using high-resolution spectra of Ni ii recorded using Fourier transform (FT) spectroscopy of continuous, nickel-helium hollow cathode discharge sources in the region 143-5555 nm (1800-70,000 cm−1, the analysis of 1016 Ni ii lines confirmed and optimized 206 previously reported energy levels of the (3 F) parent term, from 3d 8(3 F)5f to 3d 8(3 F)9s, lying between 122,060 and 138,563 cm−1. The uncertainties of these levels have been improved by at least an order of magnitude compared with their previously reported values. With the increased resolution and spectral range of the FT measurements, compared to previously published grating spectra, we were able to extend our analysis to identify and establish 33 new energy levels of Ni ii, which are reported here for the first time. Eigenvector compositions of all revised and newly established energy levels were calculated using the orthogonal operator method. In addition, an improved ionization energy of 146,541.35 ± 0.15 cm−1 for Ni ii, using highly excited levels of the 3d 8(3 F)5g, 3d 8(3 F)6g, and 3d 8(3 F)6h configurations, has been derived.

  • Journal article
    Giacalone J, Cohen CMS, McComas DJ, Chen X, Dayeh MA, Matthaeus WH, Klein KG, Bale SD, Christian ER, Desai MI, Hill ME, Khoo LY, Lario D, Leske RA, McNutt RL, Mitchell DG, Mitchell JG, Malandraki O, Schwadron NAet al., 2023,

    Analyses of ∼0.05-2 MeV Ions Associated with the 2022 February 16 Energetic Storm Particle Event Observed by Parker Solar Probe

    , Astrophysical Journal, Vol: 958, ISSN: 0004-637X

    We present analyses of 0.05-2 MeV ions from the 2022 February 16 energetic storm particle event observed by Parker Solar Probe's (PSP) IS⊙IS/EPI-Lo instrument at 0.35 au from the Sun. This event was characterized by an enhancement in ion fluxes from a quiet background, increasing gradually with time with a nearly flat spectrum, rising sharply near the arrival of the coronal mass ejection (CME)-driven shock, becoming nearly a power-law spectrum, then decaying exponentially afterward, with a rate that was independent of energy. From the observed fluxes, we determine diffusion coefficients, finding that far upstream of the shock the diffusion coefficients are nearly independent of energy, with a value of 1020 cm2 s−1. Near the shock, the diffusion coefficients are more than 1 order of magnitude smaller and increase nearly linearly with energy. We also determine the source of energetic particles, by comparing ratios of the intensities at the shock to estimates of the quiet-time intensity to predictions from diffusive shock acceleration theory. We conclude that the source of energetic ions is mostly the solar wind for this event. We also present potential interpretations of the near-exponential decay of the intensity behind the shock. One possibility we suggest is that the shock was overexpanding when it crossed PSP and the energetic particle intensity decreased behind the shock to fill the expanding volume. Overexpanding CMEs could well be more common closer to the Sun, and this is an example of such a case.

  • Journal article
    Lorfing CY, Reid HAS, Gómez-Herrero R, Maksimovic M, Nicolaou G, Owen CJ, Rodriguez-Pacheco J, Ryan DF, Trotta D, Verscharen Det al., 2023,

    Solar Electron Beam—Langmuir Wave Interactions and How They Modify Solar Electron Beam Spectra: Solar Orbiter Observations of a Match Made in the Heliosphere

    , Astrophysical Journal, Vol: 959, ISSN: 0004-637X

    Solar Orbiter's four in situ instruments have recorded numerous energetic electron events at heliocentric distances between 0.5 and 1 au. We analyze energetic electron fluxes, spectra, pitch-angle distributions, associated Langmuir waves, and type III solar radio bursts for three events to understand what causes modifications in the electron flux and identify the origin and characteristics of features observed in the electron spectrum. We investigate what electron beam properties and solar wind conditions are associated with Langmuir wave growth and spectral breaks in the electron peak flux as a function of energy. We observe velocity dispersion and quasilinear relaxation in the electron flux caused by the resonant wave-particle interactions in the deca-keV range, at the energies at which we observe breaks in the electron spectrum, cotemporal with the local generation of Langmuir waves. We show, via the evolution of the electron flux at the time of the event, that these interactions are responsible for the spectral signatures observed around 10 and 50 keV, confirming the results of simulations by Kontar and Reid. These signatures are independent of pitch-angle scattering. Our findings highlight the importance of using overlapping FOVs when working with data from different sensors. In this work, we exploit observations from all in situ instruments to address, for the first time, how the energetic electron flux is modified by the beam-plasma interactions and results in specific feature appearing in the local spectrum. Our results, corroborated with numerical simulations, can be extended to a wider range of heliocentric distances.

  • Journal article
    Rasca AP, Farrell WM, Gruesbeck JR, MacDowall RJ, Bale SD, Kasper JCet al., 2023,

    Switchbacks and Associated Magnetic Holes Observed near the Alfvén Critical Surface

    , Astrophysical Journal, Vol: 959, ISSN: 0004-637X

    During recent solar encounters, the Parker Solar Probe (PSP) began its initial dips below the Alfvén critical surface to measure in situ the sub-Alfvénic coronal wind. While the near-Sun super-Alfvénic solar wind is shown to be dominated by impulsive magnetic switchbacks (short magnetic field reversals), these brief encounters with the sub-Alfvénic coronal wind show switchbacks and associated magnetic holes (MHs) to still be present but different in character. In this work, we compare and contrast specific features of the switchbacks, including the change in B r and V r and associated boundary B-field dropouts (MHs) at locations when PSP was both above and below the Alfvén critical surface. We use observations from the PSP perihelion Encounters 8 (E8) and 12 (E12) in the analysis. We first perform a superposed epoch analysis to identify common features in the switchback boundaries, including the formation of the associated ∣B∣ dropouts/MHs in slow and fast flows. We then examine the presence of B-field dropouts/MHs as a function of Alfvén Mach number, M A. From E12, we find that the switchbacks have a systematic reduction in rotation (and reduction in B r deflection) with decreasing M A. Further, the ∣B∣ dropouts/MHs associated with the boundaries were also found to decrease in strength and occurrence with M A (with no or few ∣B∣ dropouts at M A < 0.7). The results suggest that the switchback rotation and boundary-associated MHs are connected, possibly consistent with diamagnetic effects at the boundary that require large rotations to be initiated.

  • Journal article
    Rosenfeld D, Kokhanovsky A, Goren T, Gryspeerdt E, Hasekamp O, Jia H, Lopatin A, Quaas J, Pan Z, Sourdeval Oet al., 2023,

    Frontiers in satellite‐based estimates of cloud‐mediated aerosol forcing

    , Reviews of Geophysics, Vol: 61, ISSN: 8755-1209

    Atmospheric aerosols affect the Earth's climate in many ways, including acting as the seeds on which cloud droplets form. Since a large fraction of these particles is anthropogenic, the clouds' microphysical and radiative characteristics are influenced by human activity on a global scale leading to important climatic effects. The respective change in the energy budget at the top of the atmosphere is defined as the effective radiative forcing due to aerosol-cloud interaction (ERFaci). It is estimated that the ERFaci offsets presently nearly 1/4 of the greenhouse-induced warming, but the uncertainty is within a factor of two. A common method to calculate the ERFaci is by the multiplication of the susceptibility of the cloud radiative effect to changes in aerosols by the anthropogenic change of the aerosol concentration. This has to be done by integrating it over all cloud regimes. Here we review the various methods of the ERFaci estimation. Global measurements require satellites' global coverage. The challenge of quantifying aerosol amounts in cloudy atmospheres are met with the rapid development of novel methodologies reviewed here. The aerosol characteristics can be retrieved from space based on their optical properties, including polarization. The concentrations of the aerosols that serve as cloud drop condensation nuclei can be also estimated from their impact on the satellite-retrieved cloud drop number concentrations. These observations are critical for reducing the uncertainty in the ERFaci calculated from global climate models (GCMs), but further development is required to allow GCMs to properly simulate and benefit these novel observables.

  • Journal article
    Hwang K-J, Nakamura R, Eastwood JP, Fuselier SA, Hasegawa H, Nakamura T, Lavraud B, Dokgo K, Turner DL, Ergun RE, Reiff PHet al., 2023,

    Cross-scale processes of magnetic reconnection

    , Space Science Reviews, Vol: 219, ISSN: 0038-6308

    Various physical processes in association with magnetic reconnection occur over multiple scales from the microscopic to macroscopic scale lengths. This paper reviews multi-scale and cross-scale aspects of magnetic reconnection revealed in the near-Earth space beyond the general global-scale features and magnetospheric circulation organized by the Dungey Cycle. Significant and novel advancements recently reported, in particular, since the launch of the Magnetospheric Multi-scale mission (MMS), are highlighted being categorized into different locations with different magnetic topologies. These potentially paradigm-shifting findings include shock and foreshock transient driven reconnection, magnetosheath turbulent reconnection, flow shear driven reconnection, multiple X-line structures generated in the dayside/flankside/nightside magnetospheric current sheets, development and evolution of reconnection-driven structures such as flux transfer events, flux ropes, and dipolarization fronts, and their interactions with ambient plasmas. The paper emphasizes key aspects of kinetic processes leading to multi-scale structures and bringing large-scale impacts of magnetic reconnection as discovered in the geospace environment. These key features can be relevant and applicable to understanding other heliospheric and astrophysical systems.

  • Journal article
    Hartinger MD, Elsden T, Archer MO, Takahashi K, Wright AN, Artemyev A, Zhang X, Angelopoulos Vet al., 2023,

    Properties of Magnetohydrodynamic normal modes in the Earth's magnetosphere

    , JGR: Space Physics, Vol: 128, ISSN: 2169-9402

    The Earth's magnetosphere supports a variety of Magnetohydrodynamic (MHD) normal modes with Ultra Low Frequencies (ULF) including standing Alfvén waves and cavity/waveguide modes. Their amplitudes and frequencies depend in part on the properties of the magnetosphere (size of cavity, wave speed distribution). In this work, we use ∼13 years of Time History of Events and Macroscale Interactions during Substorms satellite magnetic field observations, combined with linearized MHD numerical simulations, to examine the properties of MHD normal modes in the region L > 5 and for frequencies <80 mHz. We identify persistent normal mode structure in observed dawn sector power spectra with frequency-dependent wave power peaks like those obtained from simulation ensemble averages, where the simulations assume different radial Alfvén speed profiles and magnetopause locations. We further show with both observations and simulations how frequency-dependent wave power peaks at L > 5 depend on both the magnetopause location and the location of peaks in the radial Alfvén speed profile. Finally, we discuss how these results might be used to better model radiation belt electron dynamics related to ULF waves.

  • Journal article
    Klein KG, Spence H, Alexandrova O, Argall M, Arzamasskiy L, Bookbinder J, Broeren T, Caprioli D, Case A, Chandran B, Chen L-J, Dors I, Eastwood J, Forsyth C, Galvin A, Genot V, Halekas J, Hesse M, Hine B, Horbury T, Jian L, Kasper J, Kretzschmar M, Kunz M, Lavraud B, Le Contel O, Mallet A, Maruca B, Matthaeus W, Niehof J, OBrien H, Owen C, Retinò A, Reynolds C, Roberts O, Schekochihin A, Skoug R, Smith C, Smith S, Steinberg J, Stevens M, Szabo A, TenBarge J, Torbert R, Vasquez B, Verscharen D, Whittlesey P, Wickizer B, Zank G, Zweibel Eet al., 2023,

    HelioSwarm: a multipoint, multiscale mission to characterize turbulence

    , Space Science Reviews, Vol: 219, ISSN: 0038-6308

    HelioSwarm (HS) is a NASA Medium-Class Explorer mission of the Heliophysics Division designed to explore the dynamic three-dimensional mechanisms controlling the physics of plasma turbulence, a ubiquitous process occurring in the heliosphere and in plasmas throughout the universe. This will be accomplished by making simultaneous measurements at nine spacecraft with separations spanning magnetohydrodynamic and sub-ion spatial scales in a variety of near-Earth plasmas. In this paper, we describe the scientific background for the HS investigation, the mission goals and objectives, the observatory reference trajectory and instrumentation implementation before the start of Phase B. Through multipoint, multiscale measurements, HS promises to reveal how energy is transferred across scales and boundaries in plasmas throughout the universe.

  • Journal article
    Eglinton TI, Graven HD, Raymond PA, Trumbore SE, Aluwihare L, Bard E, Basu S, Friedlingstein P, Hammer S, Lester J, Sanderman J, Schuur EAG, Sierra CA, Synal H-A, Turnbull JC, Wacker Let al., 2023,

    Making the case for an International Decade of Radiocarbon

    , Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol: 381, ISSN: 1364-503X

    Radiocarbon (14C) is a critical tool for understanding the global carbon cycle. During the Anthropocene, two new processes influenced 14C in atmospheric, land and ocean carbon reservoirs. First, 14C-free carbon derived from fossil fuel burning has diluted 14C, at rates that have accelerated with time. Second, 'bomb' 14C produced by atmospheric nuclear weapon tests in the mid-twentieth century provided a global isotope tracer that is used to constrain rates of air-sea gas exchange, carbon turnover, large-scale atmospheric and ocean transport, and other key C cycle processes. As we write, the 14C/12C ratio of atmospheric CO2 is dropping below pre-industrial levels, and the rate of decline in the future will depend on global fossil fuel use and net exchange of bomb 14C between the atmosphere, ocean and land. This milestone coincides with a rapid increase in 14C measurement capacity worldwide. Leveraging future 14C measurements to understand processes and test models requires coordinated international effort-a 'decade of radiocarbon' with multiple goals: (i) filling observational gaps using archives, (ii) building and sustaining observation networks to increase measurement density across carbon reservoirs, (iii) developing databases, synthesis and modelling tools and (iv) establishing metrics for identifying and verifying changes in carbon sources and sinks. This article is part of the Theo Murphy meeting issue 'Radiocarbon in the Anthropocene'.

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&respub-action=search.html Current Millis: 1710832958125 Current Time: Tue Mar 19 07:22:38 GMT 2024