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Journal articleCastrillejo M, Hansman RL, Graven HD, et al., 2023,
Comparability of radiocarbon measurements in dissolved inorganic carbon of seawater produced at ETH-Zurich
, Radiocarbon: an international journal of cosmogenic isotope research, ISSN: 0033-8222Radiocarbon observations (Δ14C) in dissolved inorganic carbon (DIC) of seawater provide useful information about ocean carbon cycling and ocean circulation. To deliver high-quality observations, the Laboratory of Ion Beam Physics (LIP) at ETH-Zurich developed a new simplified method allowing the rapid analysis of radiocarbon in DIC of small seawater samples, which is continually assessed by following internal quality controls. However, a comparison with externally produced 14C measurements to better establish an equivalency between methods was still missing. Here, we make the first intercomparison with the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility based on 14 duplicate seawater samples collected in 2020. We also compare with prior deep-water observations from the 1970s to 1990s. The results show a very good agreement in both comparisons. The mean Δ14C of 12 duplicate samples measured by LIP and NOSAMS were statistically identical within one sigma uncertainty while two other duplicate samples agreed within two sigma. Based on this small number of duplicate samples, LIP values appear to be slightly lower than the NOSAMS values, but more measurements will be needed for confirmation. We also comment on storage and preservation techniques used in this study, including the freezing of samples collected in foil bags.
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Journal articleSoljento JE, Good SW, Osmane A, et al., 2023,
Imbalanced Turbulence Modified by Large-scale Velocity Shears in the Solar Wind
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 946, ISSN: 2041-8205 -
Journal articleBassett N, Rapetti D, Nhan BD, et al., 2023,
Constraining a Model of the Radio Sky below 6 MHz Using the Parker Solar Probe/FIELDS Instrument in Preparation for Upcoming Lunar-based Experiments
, ASTROPHYSICAL JOURNAL, Vol: 945, ISSN: 0004-637X -
Journal articleRaouafi NE, Stenborg G, Seaton DB, et al., 2023,
Magnetic Reconnection as the Driver of the Solar Wind
, ASTROPHYSICAL JOURNAL, Vol: 945, ISSN: 0004-637X- Author Web Link
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- Citations: 17
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Journal articleElsden T, Southwood DJ, 2023,
Modeling features of field line resonance observable by a single spacecraft at Saturn
, JGR: Space Physics, Vol: 128, Pages: 1-21, ISSN: 2169-9402The observations of Southwood et al. (2021, https://doi.org/10.1029/2020JA028473), using data from the Cassini magnetometer from the final (proximal) orbits of the mission at Saturn, show large scale azimuthally polarized magnetic signals are always present near periapsis. The signals were attributed to standing Alfvén waves excited on the magnetic shells planetward of the Saturn D-ring. The apparent absence of any systematic variation in frequency as the spacecraft crossed magnetic shells, implied that the signals were not simply locally excited standing Alfvén modes, but were pumped by coupling to global compressional eigenmodes excited in a cavity formed in the dayside magnetosphere. In this study, we use a numerical magnetohydrodynamic (MHD) model to test such theoretical explanations for the observations, by examining in detail the MHD wave coupling and large scale spatial structure of the signals. The modeling not only shows good agreement with the data but further provides new insight into features previously overlooked in the data. In particular, we show how the apparent frequency of a single spacecraft observation is affected by the phase variation present in a local field line resonance.
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Journal articleArcher M, Hartinger MD, Rastatter L, et al., 2023,
Auroral, ionospheric and ground magnetic signatures of magnetopause surface modes
, Journal of Geophysical Research: Space Physics, Vol: 128, Pages: 1-25, ISSN: 2169-9380Surface waves on Earth's magnetopause have a controlling effect upon global magnetospheric dynamics. Since spacecraft provide sparse in situ observation points, remote sensing these modes using ground-based instruments in the polar regions is desirable. However, many open conceptual questions on the expected signatures remain. Therefore, we provide predictions of key qualitative features expected in auroral, ionospheric, and ground magnetic observations through both magnetohydrodynamic theory and a global coupled magnetosphere-ionosphere simulation of a magnetopause surface eigenmode. These show monochromatic oscillatory field-aligned currents (FACs), due to both the surface mode and its non-resonant Alfvén coupling, are present throughout the magnetosphere. The currents peak in amplitude at the equatorward edge of the magnetopause boundary layer, not the open-closed boundary as previously thought. They also exhibit slow poleward phase motion rather than being purely evanescent. We suggest the upward FAC perturbations may result in periodic auroral brightenings. In the ionosphere, convection vortices circulate the poleward moving FAC structures. Finally, surface mode signals are predicted in the ground magnetic field, with ionospheric Hall currents rotating perturbations by approximately (but not exactly) 90° compared to the magnetosphere. Thus typical dayside magnetopause surface modes should be strongest in the East-West ground magnetic field component. Overall, all ground-based signatures of the magnetopause surface mode are predicted to have the same frequency across L-shells, amplitudes that maximize near the magnetopause's equatorward edge, and larger latitudinal scales than for field line resonance. Implications in terms of ionospheric Joule heating and geomagnetically induced currents are discussed.
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Journal articleBrandt PC, Provornikova E, Bale SD, et al., 2023,
Future Exploration of the Outer Heliosphere and Very Local Interstellar Medium by Interstellar Probe
, SPACE SCIENCE REVIEWS, Vol: 219, ISSN: 0038-6308- Author Web Link
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- Citations: 4
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Journal articleGieseler J, Dresing N, Palmroos C, et al., 2023,
Solar-MACH: An open-source tool to analyze solar magnetic connection configurations
, FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, Vol: 9, ISSN: 2296-987X- Author Web Link
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- Citations: 6
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Journal articleSibeck DGG, Murphy KRR, Porter FS, et al., 2023,
Quantifying the global solar wind-magnetosphere interaction with the Solar-Terrestrial Observer for the Response of the Magnetosphere (STORM) mission concept
, FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, Vol: 10, ISSN: 2296-987X -
Journal articleKrasnoselskikh V, Tsurutani BT, Dudok de Wit T, et al., 2023,
ICARUS: in-situ studies of the solar corona beyond Parker Solar Probe and Solar Orbiter
, Experimental Astronomy, Vol: 54, Pages: 277-315, ISSN: 0922-6435The primary scientific goal of ICARUS (Investigation of Coronal AcceleRation and heating of solar wind Up to the Sun), a mother-daughter satellite mission, proposed in response to the ESA “Voyage 2050” Call, will be to determine how the magnetic field and plasma dynamics in the outer solar atmosphere give rise to the corona, the solar wind, and the entire heliosphere. Reaching this goal will be a Rosetta Stone step, with results that are broadly applicable within the fields of space plasma physics and astrophysics. Within ESA’s Cosmic Vision roadmap, these science goals address Theme 2: “How does the Solar System work?” by investigating basic processes occurring “From the Sun to the edge of the Solar System”. ICARUS will not only advance our understanding of the plasma environment around our Sun, but also of the numerous magnetically active stars with hot plasma coronae. ICARUS I will perform the first direct in situ measurements of electromagnetic fields, particle acceleration, wave activity, energy distribution, and flows directly in the regions in which the solar wind emerges from the coronal plasma. ICARUS I will have a perihelion altitude of 1 solar radius and will cross the region where the major energy deposition occurs. The polar orbit of ICARUS I will enable crossing the regions where both the fast and slow winds are generated. It will probe the local characteristics of the plasma and provide unique information about the physical processes involved in the creation of the solar wind. ICARUS II will observe this region using remote-sensing instruments, providing simultaneous, contextual information about regions crossed by ICARUS I and the solar atmosphere below as observed by solar telescopes. It will thus provide bridges for understanding the magnetic links between the heliosphere and the solar atmosphere. Such information is crucial to our understanding of the plasma physics and electrodynamics of the solar atmosph
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Journal articleShi C, Velli M, Lionello R, et al., 2023,
Proton and Electron Temperatures in the Solar Wind and Their Correlations with the Solar Wind Speed
, ASTROPHYSICAL JOURNAL, Vol: 944, ISSN: 0004-637X- Author Web Link
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- Citations: 1
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Journal articleMcComas DJ, Sharma T, Christian ER, et al., 2023,
Parker Solar Probe Encounters the Leg of a Coronal Mass Ejection at 14 Solar Radii
, ASTROPHYSICAL JOURNAL, Vol: 943, ISSN: 0004-637X- Author Web Link
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- Citations: 3
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Journal articleRaouafi NE, Matteini L, Squire J, et al., 2023,
Parker solar probe: four years of discoveries at solar cycle minimum
, Space Science Reviews, Vol: 219, Pages: 1-140, ISSN: 0038-6308Launched on 12 Aug. 2018, NASA’s Parker Solar Probe had completed 13 of its scheduled 24 orbits around the Sun by Nov. 2022. The mission’s primary science goal is to determine the structure and dynamics of the Sun’s coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what processes accelerate energetic particles. Parker Solar Probe returned a treasure trove of science data that far exceeded quality, significance, and quantity expectations, leading to a significant number of discoveries reported in nearly 700 peer-reviewed publications. The first four years of the 7-year primary mission duration have been mostly during solar minimum conditions with few major solar events. Starting with orbit 8 (i.e., 28 Apr. 2021), Parker flew through the magnetically dominated corona, i.e., sub-Alfvénic solar wind, which is one of the mission’s primary objectives. In this paper, we present an overview of the scientific advances made mainly during the first four years of the Parker Solar Probe mission, which go well beyond the three science objectives that are: (1) Trace the flow of energy that heats and accelerates the solar corona and solar wind; (2) Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind; and (3) Explore mechanisms that accelerate and transport energetic particles.
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Journal articleLiu YD, Ran H, Hu H, et al., 2023,
On the Generation and Evolution of Switchbacks and the Morphology of the Alfvenic Transition: Low Mach-number Boundary Layers
, ASTROPHYSICAL JOURNAL, Vol: 944, ISSN: 0004-637X -
Journal articleTrattner KJ, Fuselier SA, Schwartz SJ, et al., 2023,
Ion Acceleration at the Quasi-Parallel Shock: The Source Distributions of the Diffuse Ions
, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 128, ISSN: 2169-9380- Author Web Link
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- Citations: 1
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Journal articleMoses JI, Brown ZL, Koskinen TT, et al., 2023,
Saturn’s atmospheric response to the large influx of ring material inferred from Cassini INMS measurements
, Icarus, Vol: 391, Pages: 1-40, ISSN: 0019-1035During the Grand Finale stage of the Cassini mission, organic-rich ring material was discovered to be flowing into Saturn’s equatorial upper atmosphere at a surprisingly large rate. Through a series of photochemical models, we have examined the consequences of this ring material on the chemistry of Saturn’s neutral and ionized atmosphere. We find that if a substantial fraction of this material enters the atmosphere as vapor or becomes vaporized as the solid ring particles ablate upon atmospheric entry, then the ring-derived vapor would strongly affect the composition of Saturn’s ionosphere and neutral stratosphere. Our surveys of Cassini infrared and ultraviolet remote-sensing data from the final few years of the mission, however, reveal none of these predicted chemical consequences. We therefore conclude that either (1) the inferred ring influx represents an anomalous, transient situation that was triggered by some recent dynamical event in the ring system that occurred a few months to a few tens of years before the 2017 end of the Cassini mission, or (2) a large fraction of the incoming material must have been entering the atmosphere as small dust particles less than 100 nm in radius, rather than as vapor or as large particles that are likely to ablate. Future observations or upper limits for stratospheric neutral species such as HCN, HCN, and CO at infrared wavelengths could shed light on the origin, timing, magnitude, and nature of a possible vapor-rich ring-inflow event.
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Journal articlePhillips C, Bandyopadhyay R, McComas DJ, et al., 2023,
Association of intermittency with electron heating in the near-Sun solar wind
, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 519, Pages: L1-L4, ISSN: 0035-8711 -
Journal articleTrotta D, Hietala H, Horbury T, et al., 2023,
Multi-spacecraft observations of shocklets at an interplanetary shock
, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 520, Pages: 437-445, ISSN: 0035-8711- Author Web Link
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- Citations: 2
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Journal articleZomerdijk-Russell S, Masters A, Korth H, et al., 2023,
Modelling the time-dependent magnetic fields that BepiColombo will use to probe down into Mercury’s mantle
, Geophysical Research Letters, Vol: 50, ISSN: 0094-8276External solar wind variability causes motion of the magnetopause and changes of this boundary's current structure, and the resulting inductive processes, may be exploited to determine the interior structure of magnetized planets. In preparation for the arrival of the BepiColombo spacecraft at Mercury, we here assess solar wind ram pressure forcing in this planet's environment, through analysis of data acquired by the Helios spacecraft, and the impact on the magnetopause's inducing field. These measurements suggest that BepiColombo will see highly unpredictable solar wind conditions and that the inducing field generated in response to variable solar wind ram pressure is non-uniform across the planet's surface. The inducing magnetic field spectrum, with frequencies in the range of ∼5.5 x10¯⁵ -1.5 x 10¯²Hz, suggests that the transfer functions derived from the two BepiColombo spacecraft could allow us to obtain a profile of conductivity through Mercury's crust and mantle.
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Journal articleDe Marco R, Bruno R, Jagarlamudi VK, et al., 2023,
Innovative technique for separating proton core, proton beam, and alpha particles in solar wind 3D velocity distribution functions
, ASTRONOMY & ASTROPHYSICS, Vol: 669, ISSN: 0004-6361- Author Web Link
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- Citations: 1
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Journal articleMaffei S, Eggington JWB, Livermore PW, et al., 2023,
Climatological predictions of the auroral zone locations driven by moderate and severe space weather events
, Scientific Reports, Vol: 13, Pages: 1-11, ISSN: 2045-2322Auroral zones are regions where, in an average sense, aurorae due to solar activity are most likely spotted. Their shape and, similarly, the geographical locations most vulnerable to extreme space weather events (which we term ‘danger zones’) are modulated by Earth’s time-dependent internal magnetic field whose structure changes on yearly to decadal timescales. Strategies for mitigating ground-based space weather impacts over the next few decades can benefit from accurate forecasts of this evolution. Existing auroral zone forecasts use simplified assumptions of geomagnetic field variations. By harnessing the capability of modern geomagnetic field forecasts based on the dynamics of Earth’s core we estimate the evolution of the auroral zones and of the danger zones over the next 50 years. Our results predict that space-weather related risk will not change significantly in Europe, Australia and New Zealand. Mid-to-high latitude cities such as Edinburgh, Copenhagen and Dunedin will remain in high-risk regions. However, northward change of the auroral and danger zones over North America will likely cause urban centres such as Edmonton and Labrador City to be exposed by 2070 to the potential impact of severe solar activity.
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Journal articleClear CP, Uylings P, Raassen T, et al., 2023,
New Ritz wavelengths and transition probabilities for parity-forbidden, singly ionized nickel [Ni II] lines of astrophysical interest
, Monthly Notices of the Royal Astronomical Society, Vol: 519, Pages: 4040-4046, ISSN: 0035-8711We report accurate Ritz wavelengths for parity-forbidden [Ni II] transitions, derived from energy levels determined using high-resolution Fourier transform spectroscopy. Transitions between the 18 lowest Ni II energy levels of even-parity produced Ritz wavelengths for 126 parity-forbidden lines. Uncertainties for the Ritz wavelengths derived in this work are up to two orders of magnitude lower than previously published values. Transition probabilities were calculated using the semi-empirical orthogonal operator method, with uncertainties ranging from approximately 1 per cent for strong M1 lines and up to 10 per cent for weak E2 lines. Accurate forbidden line wavelengths and transition probabilities, particularly for lines in the infrared, are important in the analyses of low-density astrophysical plasmas, such as supernova remnants, planetary nebulae, and active galactic nuclei.
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Journal articleBreul P, Ceppi P, Shepherd TG, 2023,
Revisiting the wintertime emergent constraint of the southern hemispheric midlatitude jet response to global warming
, Weather and Climate Dynamics, Vol: 4, Pages: 39-47, ISSN: 2698-4016Most climate models show a poleward shift of the southern hemispheric zonal-mean jet in response to climate change, but the inter-model spread is large. In an attempt to constrain future jet responses, past studies have identified an emergent constraint between the climatological jet latitude and the future jet shift in austral winter. However, we show that the emergent constraint only arises in the zonal mean and not in separate halves of the hemisphere, which questions the physicality of the emergent constraint. We further find that the zonal-mean jet latitude does not represent the latitude of a zonally coherent structure, due to the presence of a double-jet structure in the Pacific region during this season. The zonal asymmetry causes the previously noted large spread in the zonal-mean climatology but not in the response, which underlies the emergent constraint. We therefore argue that the emergent constraint on the zonal-mean jet cannot narrow down the spread in future wind responses, and we propose that emergent constraints on the jet response in austral winter should be based on regional rather than zonal-mean circulation features.
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Journal articleVuorinen L, Lamoury A, Masongsong E, et al., 2023,
SPACE RAINDROPS SPLASHING ON EARTH’S MAGNETIC UMBRELLA
, Eos (United States), Vol: 104, Pages: 35-39, ISSN: 0096-3941Every few minutes, enormous “droplets” of plasma rain down from space toward Earth. Instead of crashing catastrophically to the ground, these droplets, called magnetosheath jets, are deflected by the outer reaches of Earth’s magnetic field. Despite the frequent occurrence of magnetosheath jets near Earth and their likely ubiquity across the solar system, their study is young and there is much we do not know about their origins and behavior. Specifi-cally, their potential effects on space weather—the phenomena we experience on Earth due to the ever changing stream of plasma that flows through our solar system—are unclear and still being investigated. Therefore, these jets are currently not factored into space weather models or predictions. Here we dis-cuss recent findings in this field and important questions that remain to be answered.
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Journal articleLotz S, Nel AE, Wicks RT, et al., 2023,
The Radial Variation of the Solar Wind Turbulence Spectra near the Kinetic Break Scale from Parker Solar Probe Measurements
, ASTROPHYSICAL JOURNAL, Vol: 942, ISSN: 0004-637X- Author Web Link
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- Citations: 2
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Conference paperEckersley S, Rowe S, Hill W, et al., 2023,
An ESA Nanosatellite Constellation to Monitor Space Weather Effects
, ISSN: 0074-1795Major space weather events have the potential to cause significant damage and disruption to critical terrestrial and space-based infrastructure, including radio communication networks, Global Navigation Satellite Systems (GNSS) and the electricity grid. The continuous monitoring of space weather is therefore crucial for providing advanced warning of potentially destructive events. The European Space Agency (ESA) is in the process of developing the Enhanced Space Weather Monitoring System, which will utilise spacecraft to monitor space weather on and away from the Sun-Earth line (e.g., the ESA Vigil mission). The Distributed Space Weather Sensor System (D3S) will form part of this Enhanced Space Weather Monitoring System and focus on making measurements in the vicinity of the Earth. In early 2021, SSTL was selected to lead an ESA-funded Phase 0/A study titled “SSA P3-SWE-LIII Nanosatellites for D3S”. The aim of the study was to establish the role that nanosatellites can play as part of the D3S space weather monitoring system. Nanosatellite technologies have seen significant performance and capability improvements in recent years, and this was one of the reasons that nanosatellites were of particular interest for this study, along with the benefit of their small size and lower costs. The objective of the Phase 0 study was to analyse the space weather measurement requirements for the mission and identify potential space weather instruments that could be accommodated on a nanosatellite mission. A trade-off of a range of different mission architecture concepts was conducted, and the two most promising concepts were selected for more detailed analysis in the latter half of the Phase 0 study. At the end of Phase 0, ESA selected a concept comprising 6x 16U SSTL CubeSats in a 500-600km Sun-Synchronous Orbit to take forward into Phase A for further definition. The Phase A study focussed on the more detailed design of a precursor demonstration mission comprised of
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Journal articleSioulas N, Huang Z, Shi C, et al., 2023,
Magnetic field spectral evolution in the inner heliosphere
, Letters of the Astrophysical Journal, Vol: 943, Pages: 1-7, ISSN: 2041-8205Parker Solar Probe and Solar Orbiter data are used to investigate the radial evolution of magnetic turbulence between 0.06 ≲ R ≲ 1 au. The spectrum is studied as a function of scale, normalized to the ion inertial scale di. In the vicinity of the Sun, the inertial range is limited to a narrow range of scales and exhibits a power-law exponent of, αB = −3/2, independent of plasma parameters. The inertial range grows with distance, progressively extending to larger spatial scales, while steepening toward a αB = −5/3 scaling. It is observed that spectra for intervals with large magnetic energy excesses and low Alfvénic content steepen significantly with distance, in contrast to highly Alfvénic intervals that retain their near-Sun scaling. The occurrence of steeper spectra in slower wind streams may be attributed to the observed positive correlation between solar wind speed and Alfvénicity.
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Journal articleGingell I, Schwartz SJ, Kucharek H, et al., 2023,
Hybrid simulations of the decay of reconnected structures downstream of the bow shock
, PHYSICS OF PLASMAS, Vol: 30, ISSN: 1070-664X- Author Web Link
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- Citations: 3
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Journal articleSun J, Vasko IY, Bale SD, et al., 2022,
Double Layers in the Earth's Bow Shock
, GEOPHYSICAL RESEARCH LETTERS, Vol: 49, ISSN: 0094-8276- Author Web Link
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- Citations: 1
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Journal articleXie X, Myhre G, Shindell D, et al., 2022,
Anthropogenic sulfate aerosol pollution in South and East Asia induces increased summer precipitation over arid Central Asia
, COMMUNICATIONS EARTH & ENVIRONMENT, Vol: 3
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