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Journal articleMurray JE, Brindley HE, Fox S, et al., 2020,
Retrievals of high latitude surface emissivity across the infrared from high altitude aircraft flights
, Journal of Geophysical Research: Atmospheres, Vol: 125, Pages: 1-16, ISSN: 2169-897XWe present retrievals of infrared spectral surface emissivities spanning the far and mid infrared from aircraft observations over Greenland, taken at an altitude of 9.2 km above sea level. We describe the flight campaign, available measurements and the retrieval method. The principal barriers to reducing uncertainty in the emissivity retrievals are found to be instrumental noise and our ability to simultaneously retrieve the underlying surface temperature. However, our results indicate that using the instrumentation available to us it is possible to retrieve emissivities from altitude with an uncertainty of ~ 0.02 or better across much of the infrared. They confirm that the far‐infrared emissivity of snow and ice surfaces can depart substantially from unity, reaching values as low as 0.9 between 400‐450 cm‐1. They also show good consistency with retrievals from the same flight made from near‐surface observations giving confidence in the methodology used and the results obtained for this more challenging viewing configuration. To the best of our knowledge, this is the first time that far‐infrared surface emissivity has been retrieved from altitude and demonstrates that the methodology has the potential to be extended to planned satellite far‐infrared missions.
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Journal articleMansfield L, Nowack P, Kasoar M, et al., 2020,
Predicting global patterns of long-term climate change from short-term simulations using machine learning
, npj Climate and Atmospheric Science, Vol: 3, ISSN: 2397-3722Understanding and estimating regional climate change under different anthropogenic emission scenarios is pivotal for informing societal adaptation and mitigation measures. However, the high computational complexity of state-of-the-art climate models remains a central bottleneck in this endeavour. Here we introduce a machine learning approach, which utilises a unique dataset of existing climate model simulations to learn relationships between short-te¬rm and long-term temperature responses to different climate forcing scenarios. This approach not only has the potential to accelerate climate change projections by reducing the costs of scenario computations, but also helps uncover early indicators of modelled long-term climate responses, which is of relevance to climate change detection, predictability and attribution. Our results highlight challenges and opportunities for data-driven climate modelling, especially concerning the incorporation of even larger model datasets in the future. We therefore encourage extensive data sharing among research institutes to build ever more powerful climate response emulators, and thus to enable faster climate change projections.
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Journal articleCarnielli G, Galand M, Leblanc F, et al., 2020,
Simulations of ion sputtering at Ganymede
, Icarus, Vol: 351, Pages: 1-11, ISSN: 0019-1035Ganymede's surface is subject to constant bombardment by Jovian magnetospheric and Ganymede's ionospheric ions. These populations sputter the surface and contribute to the replenishment of the moon's exosphere.Thus far, estimates for sputtering on the moon's surface have included only the contribution from Jovian ions. In this work, we have used our recent model of Ganymede's ionosphere Carnielli et al., 2019 to evaluate the contribution of ionospheric ions for the first time. In addition, we have made new estimates for the contribution from Jovian ions, including both thermal and energetic components.For Jovian ions, we find a total sputtering rate of 2.2 × 1027 s−1, typically an order of magnitude higher compared to previous estimates. For ionospheric ions, produced through photo- and electron-impact ionization, we find values in the range 2.7 × 1026–5.2 × 1027 s−1 when the moon is located above the Jovian plasma sheet. Hence, Ganymede's ionospheric ions provide a contribution of at least 10% to the sputtering rate, and under certain conditions they dominate the process. This finding indicates that the ionospheric population is an important source to consider in the context of exospheric models.
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Journal articleDavies E, Forsyth R, Good S, et al., 2020,
On the radial and longitudinal variation of a magnetic cloud: ACE, wind, ARTEMIS and Juno observations
, Solar Physics: a journal for solar and solar-stellar research and the study of solar terrestrial physics, Vol: 295, ISSN: 0038-0938We present observations of the same magnetic cloud made near Earth by the Advance Composition Explorer (ACE), Wind, and the Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun (ARTEMIS) mission comprising the Time History of Events and Macroscale Interactions during Substorms (THEMIS) B and THEMIS C spacecraft, and later by Juno at a distance of 1.2 AU. The spacecraft were close to radial alignment throughout the event, with a longitudinal separation of 3.6∘ between Juno and the spacecraft near Earth. The magnetic cloud likely originated from a filament eruption on 22 October 2011 at 00:05 UT, and caused a strong geomagnetic storm at Earth commencing on 24 October. Observations of the magnetic cloud at each spacecraft have been analysed using minimum variance analysis and two flux rope fitting models, Lundquist and Gold–Hoyle, to give the orientation of the flux rope axis. We explore the effect different trailing edge boundaries have on the results of each analysis method, and find a clear difference between the orientations of the flux rope axis at the near-Earth spacecraft and Juno, independent of the analysis method. The axial magnetic field strength and the radial width of the flux rope are calculated using both observations and fitting parameters and their relationship with heliocentric distance is investigated. Differences in results between the near-Earth spacecraft and Juno are attributed not only to the radial separation, but to the small longitudinal separation which resulted in a surprisingly large difference in the in situ observations between the spacecraft. This case study demonstrates the utility of Juno cruise data as a new opportunity to study magnetic clouds beyond 1 AU, and the need for caution in future radial alignment studies.
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Journal articleBantges RJ, Brindley HE, Murray JE, et al., 2020,
A test of the ability of current bulk optical models to represent the radiative properties of cirrus cloud across the mid- and far-infrared
, Atmospheric Chemistry and Physics, Vol: 20, Pages: 12889-12903, ISSN: 1680-7316Measurements of mid- to far-infrared nadir radiances obtained from the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe 146 aircraft during the Cirrus Coupled Cloud-Radiation Experiment (CIRCCREX) are used to assess the performance of various ice cloud bulk optical property models. Through use of a minimization approach, we find that the simulations can reproduce the observed spectra in the mid-infrared to within measurement uncertainty, but they are unable to simultaneously match the observations over the far-infrared frequency range. When both mid- and far-infrared observations are used to minimize residuals, first-order estimates of the spectral flux differences between the best-performing simulations and observations indicate a compensation effect between the mid- and far-infrared such that the absolute broadband difference is < 0.7 W m−2. However, simply matching the spectra using the mid-infrared (far-infrared) observations in isolation leads to substantially larger discrepancies, with absolute differences reaching ∼ 1.8 (3.1) W m−2. These results show that simulations using these microphysical models may give a broadly correct integrated longwave radiative impact but that this masks spectral errors, with implicit consequences for the vertical distribution of atmospheric heating. They also imply that retrievals using these models applied to mid-infrared radiances in isolation will select cirrus optical properties that are inconsistent with far-infrared radiances. As such, the results highlight the potential benefit of more extensive far-infrared observations for the assessment and, where necessary, the improvement of current ice bulk optical models.
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Journal articleBunce EJ, Martindale A, Lindsay S, et al., 2020,
The BepiColombo Mercury Imaging X-Ray Spectrometer: Science Goals, Instrument Performance and Operations
, SPACE SCIENCE REVIEWS, Vol: 216, ISSN: 0038-6308- Author Web Link
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- Citations: 22
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Journal articleWoolley T, Matteini L, Horbury TS, et al., 2020,
Proton core behaviour inside magnetic field switchbacks
, Monthly Notices of the Royal Astronomical Society, Vol: 498, Pages: 5524-5531, ISSN: 0035-8711During Parker Solar Probe’s first two orbits there are widespread observations of rapid magnetic field reversals known as switchbacks. These switchbacks are extensively found in the near-Sun solar wind, appear to occur in patches, and have possible links to various phenomena such as magnetic reconnection near the solar surface. As switchbacks are associated with faster plasma flows, we questioned whether they are hotter than the background plasma and whether the microphysics inside a switchback is different to its surroundings. We have studied the reduced distribution functions from the Solar Probe Cup instrument and considered time periods with markedly large angular deflections, to compare parallel temperatures inside and outside switchbacks. We have shown that the reduced distribution functions inside switchbacks are consistent with a rigid velocity space rotation of the background plasma. As such, we conclude that the proton core parallel temperature is very similar inside and outside of switchbacks, implying that a T-V relationship does not hold for the proton core parallel temperature inside magnetic field switchbacks. We further conclude that switchbacks are consistent with Alfvénic pulses travelling along open magnetic field lines. The origin of these pulses, however, remains unknown. We also found that there is no obvious link between radial Poynting flux and kinetic energy enhancements suggesting that the radial Poynting flux is not important for the dynamics of switchbacks.
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Journal articleBlanc M, Prieto-Ballesteros O, Andre N, et al., 2020,
Joint Europa Mission (JEM) a multi-scale study of Europa to characterize its habitability and search for extant life
, Planetary and Space Science, Vol: 193, ISSN: 0032-0633Europa is the closest and probably the most promising target to search for extant life in the Solar System, based oncomplementary evidence that it may fulfil the key criteria for habitability: the Galileo discovery of a sub-surface ocean;the many indications that the ice shell is active and may be partly permeable to transfer of chemical species,biomolecules and elementary forms of life; the identification of candidate thermal and chemical energy sourcesnecessary to drive a metabolic activity near the ocean floor. In this article we are proposing that ESA collaborates withNASA to design and fly jointly an ambitious and exciting planetary mission, which we call the Joint Europa Mission(JEM), to reach two objectives: perform a full characterization of Europa’s habitability with the capabilities of a Europaorbiter, and search for bio-signatures in the environment of Europa (surface, subsurface and exosphere) by thecombination of an orbiter and a lander. JEM can build on the advanced understanding of this system which themissions preceding JEM will provide: Juno, JUICE and Europa Clipper, and on the Europa lander concept currentlydesigned by NASA (Maize, report to OPAG, 2019). We propose the following overarching goals for our proposed JointEuropa Mission (JEM): Understand Europa as a complex system responding to Jupiter system forcing, characterisethe habitability of its potential biosphere, and search for life at its surface and in its sub-surface and exosphere. Weaddress these goals by a combination of five Priority Scientific Objectives, each with focused measurement objectivesproviding detailed constraints on the science payloads and on the platforms used by the mission. The JEM observationstrategy will combine three types of scientific measurement sequences: measurements on a high-latitude, low-altitudeEuropan orbit; in-situ measurements to be performed at the surface, using a soft lander; and measurements during thefinal descent to Europa’s surface. T
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Journal articleGraven H, Keeling RF, Rogelj J, 2020,
Changes to carbon isotopes in atmospheric CO2 over the industrial era and into the future
, Global Biogeochemical Cycles: an international journal of global change, Vol: 34, Pages: 1-21, ISSN: 0886-6236In this “Grand Challenges” paper, we review how the carbon isotopic composition of atmospheric CO2 has changed since the Industrial Revolution due to human activities and their influence on the natural carbon cycle, and we provide new estimates of possible future changes for a range of scenarios. Emissions of CO2 from fossil fuel combustion and land use change reduce the ratio of 13C/12C in atmospheric CO2 (δ13CO2). This is because 12C is preferentially assimilated during photosynthesis and δ13C in plant-derived carbon in terrestrial ecosystems and fossil fuels is lower than atmospheric δ13CO2. Emissions of CO2 from fossil fuel combustion also reduce the ratio of 14C/C in atmospheric CO2 (Δ14CO2) because 14C is absent in million-year-old fossil fuels, which have been stored for much longer than the radioactive decay time of 14C. Atmospheric Δ14CO2 rapidly increased in the 1950s to 1960s because of 14C produced during nuclear bomb testing. The resulting trends in δ13C and Δ14C in atmospheric CO2 are influenced not only by these human emissions but also by natural carbon exchanges that mix carbon between the atmosphere and ocean and terrestrial ecosystems. This mixing caused Δ14CO2 to return toward preindustrial levels in the first few decades after the spike from nuclear testing. More recently, as the bomb 14C excess is now mostly well mixed with the decadally overturning carbon reservoirs, fossil fuel emissions have become the main factor driving further decreases in atmospheric Δ14CO2. For δ13CO2, in addition to exchanges between reservoirs, the extent to which 12C is preferentially assimilated during photosynthesis appears to have increased, slowing down the recent δ13CO2 trend slightly. A new compilation of ice core and flask δ13CO2 observations indicates that the decline in δ13CO2 since the preindustrial period is less than some prior estimates, which may have incorporated
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Journal articleHeyns MJ, Gaunt CT, Lotz S, et al., 2020,
Data driven transfer functions and transmission network parameters for GIC modelling
, ELECTRIC POWER SYSTEMS RESEARCH, Vol: 188, ISSN: 0378-7796- Author Web Link
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- Citations: 6
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Journal articleChen Y, Hu Q, Zhao L, et al., 2020,
Small-scale Magnetic Flux Ropes in the First Two Parker Solar Probe Encounters
, ASTROPHYSICAL JOURNAL, Vol: 903, ISSN: 0004-637X- Author Web Link
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- Citations: 19
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Journal articleChen Y, Toth G, Hietala H, et al., 2020,
Magnetohydrodynamic with embedded particle‐in‐cell simulation of the Geospace Environment Modeling dayside kinetic processes challenge event
, Earth and Space Science, Vol: 7, Pages: 1-15, ISSN: 2333-5084We use the MHD with embedded particle‐in‐cell model (MHD‐EPIC) to study the Geospace Environment Modeling (GEM) dayside kinetic processes challenge event at 01:50‐03:00 UT on 2015‐11‐18, when the magnetosphere was driven by a steady southward IMF. In the MHD‐EPIC simulation, the dayside magnetopause is covered by a PIC code so that the dayside reconnection is properly handled. We compare the magnetic fields and the plasma profiles of the magnetopause crossing with the MMS3 spacecraft observations. Most variables match the observations well in the magnetosphere, in the magnetosheath, and also during the current sheet crossing. The MHD‐EPIC simulation produces flux ropes, and we demonstrate that some magnetic field and plasma features observed by the MMS3 spacecraft can be reproduced by a flux rope crossing event. We use an algorithm to automatically identify the reconnection sites from the simulation results. It turns out that there are usually multiple X‐lines at the magnetopause. By tracing the locations of the X‐lines, we find the typical moving speed of the X‐line endpoints is about 70~km/s, which is higher than but still comparable with the ground‐based observations.
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Journal articleBarnes D, Davies JA, Harrison RA, et al., 2020,
CMEs in the heliosphere: III. a statistical analysis of the kinematic properties derived from stereoscopic geometrical modelling techniques applied to CMEs detected in the heliosphere from 2008 to 2014 by STEREO/HI-1
, Solar Physics: a journal for solar and solar-stellar research and the study of solar terrestrial physics, Vol: 295, Pages: 1-25, ISSN: 0038-0938We present an analysis of coronal mass ejections (CMEs) observed by the Heliospheric Imagers (HIs) onboard NASA’s Solar Terrestrial Relations Observatory (STEREO) spacecraft. Between August 2008 and April 2014 we identify 273 CMEs that are observed simultaneously, by the HIs on both spacecraft. For each CME, we track the observed leading edge, as a function of time, from both vantage points, and apply the Stereoscopic Self-Similar Expansion (SSSE) technique to infer their propagation throughout the inner heliosphere. The technique is unable to accurately locate CMEs when their observed leading edge passes between the spacecraft; however, we are able to successfully apply the technique to 151, most of which occur once the spacecraft-separation angle exceeds 180∘, during solar maximum. We find that using a small half-width to fit the CME can result in inferred acceleration to unphysically high velocities and that using a larger half-width can fail to accurately locate the CMEs close to the Sun because the method does not account for CME over-expansion in this region. Observed velocities from SSSE are found to agree well with single-spacecraft (SSEF) analysis techniques applied to the same events. CME propagation directions derived from SSSE and SSEF analysis agree poorly because of known limitations present in the latter.
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Journal articleMalaspina DM, Goodrich K, Livi R, et al., 2020,
Plasma Double Layers at the Boundary Between Venus and the Solar Wind
, GEOPHYSICAL RESEARCH LETTERS, Vol: 47, ISSN: 0094-8276- Author Web Link
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- Citations: 14
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Journal articleBaumjohann W, Matsuoka A, Narita Y, et al., 2020,
The BepiColombo-Mio magnetometer en route to Mercury
, Space Science Reviews, Vol: 216, Pages: 1-33, ISSN: 0038-6308The fluxgate magnetometer MGF on board the Mio spacecraft of the BepiColombo mission is introduced with its science targets, instrument design, calibration report, and scientific expectations. The MGF instrument consists of two tri-axial fluxgate magnetometers. Both sensors are mounted on a 4.8-m long mast to measure the magnetic field around Mercury at distances from near surface (initial peri-center altitude is 590 km) to 6 planetary radii (11640 km). The two sensors of MGF are operated in a fully redundant way, each with its own electronics, data processing and power supply units. The MGF instrument samples the magnetic field at a rate of up to 128 Hz to reveal rapidly-evolving magnetospheric dynamics, among them magnetic reconnection causing substorm-like disturbances, field-aligned currents, and ultra-low-frequency waves. The high time resolution of MGF is also helpful to study solar wind processes (through measurements of the interplanetary magnetic field) in the inner heliosphere. The MGF instrument firmly corroborates measurements of its companion, the MPO magnetometer, by performing multi-point observations to determine the planetary internal field at higher multi-pole orders and to separate temporal fluctuations from spatial variations.
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Journal articleQu Y, Voulgarakis A, Wang T, et al., 2020,
A study of the effect of aerosols on surface ozone through meteorologyfeedbacks over China
<jats:p>Abstract. Interactions between aerosols and gases in the atmosphere have been the focus of an increasing number of studies in recent years. Here, we focus on aerosol effects on tropospheric ozone that involve meteorological feedbacks induced by aerosol-radiation interactions. Specifically, we study the effects that involve aerosol influences on the transport of gaseous pollutants and on atmospheric moisture, both of which can impact ozone chemistry. For this purpose, we use the UK Earth System Model (UKESM1) with which we performed sensitivity simulations including and excluding the aerosol direct radiative effect (ADE) on atmospheric chemistry, and focused our analysis on an area with high aerosol presence, namely China. By comparing the simulations, we found that ADE reduced the shortwave radiation by 11 % in China, and consequently led to lower turbulent kinetic energy, weaker horizontal winds and a shallower boundary layer (with a maximum of 102.28 m reduction in north China). On the one hand, the suppressed boundary layer limited the export and diffusion of pollutants, and increased the concentration of CO, SO2, NO, NO2, PM2.5 and PM10 in the aerosol rich regions. The NO / NO2 ratio generally increased and led to more ozone depletion. On the other hand, the boundary layer top acted as a barrier that trapped moisture at lower altitudes and reduced the moisture at higher altitudes (the specific humidity was reduced by 1.69 % at 1493 m averaged in China). Due to reduced water vapor, fewer clouds were formed, and more sunlight reached the surface, so the photolytical production of ozone increased. Under the combined effect of the two meteorology feedback methods, the annual average ozone concentration in China declined by 2.01 ppb (6.2 %), which was found to bring the model in closer agreement with surface ozone measurements from different parts of China. </jats:p>
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Journal articleQu Y, Voulgarakis A, Wang T, et al., 2020,
Supplementary material to &quot;A study of the effect of aerosols on surface ozone through meteorologyfeedbacks over China&quot;
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Journal articleSparks N, Toumi R, 2020,
Pacific subsurface ocean temperature as a long-rangepredictor of South China tropical cyclone landfall
, Communications Earth & Environment, Vol: 1, ISSN: 2662-4435Seasonal forecasts of the tropical cyclones which frequently make landfall along the densely populated South China coast are highly desirable. Here, we analyse observations of landfalling tropical cyclones in South China and of subsurface ocean temperatures in the Pacific warm pool region, and identify the possibility of forecasts of South China tropical cyclone landfall a year ahead. Specifically, we define a subsurface temperature index, subNiño4, and build a predictive model based on subNiño4 anomalies with a robust double cross-validated forecast skill against climatology of 23%, similar in skill to existing forecasts issued much later in the spring. We suggest that subNiño4 ocean temperatures precede the surface El Niño/Southern Oscillation state by about 12 months, and that the zonal shifts in atmospheric heating then change mid-level winds to steer tropical cyclones towards landfall in South China. We note that regional subsurface ocean temperature anomalies may permit atmospheric predictions in other locations at a longer range than is currently thought possible.
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Journal articleFletcher, Helled, Roussos, et al., 2020,
Ice giant systems: the scientific potential of orbital missions to Uranus and Neptune
, Planetary and Space Science, Vol: 191, ISSN: 0032-0633Uranus and Neptune, and their diverse satellite and ring systems, represent the least explored environments of our Solar System, and yet may provide the archetype for the most common outcome of planetary formation throughout our galaxy. Ice Giants will be the last remaining class of Solar System planet to have a dedicated orbital explorer, and international efforts are under way to realise such an ambitious mission in the coming decades. In 2019, the European Space Agency released a call for scientific themes for its strategic science planning process for the 2030s and 2040s, known as Voyage 2050. We used this opportunity to review our present-day knowledge of the Uranus and Neptune systems, producing a revised and updated set of scientific questions and motivations for their exploration. This review article describes how such a mission could explore their origins, ice-rich interiors, dynamic atmospheres, unique magnetospheres, and myriad icy satellites, to address questions at the heart of modern planetary science. These two worlds are superb examples of how planets with shared origins can exhibit remarkably different evolutionary paths: Neptune as the archetype for Ice Giants, whereas Uranus may be atypical. Exploring Uranus' natural satellites and Neptune's captured moon Triton could reveal how Ocean Worlds form and remain active, redefining the extent of the habitable zone in our Solar System. For these reasons and more, we advocate that an Ice Giant System explorer should become a strategic cornerstone mission within ESA's Voyage 2050 programme, in partnership with international collaborators, and targeting launch opportunities in the early 2030s.
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Journal articlePickering JC, Teresa Belmonte M, Clear CP, et al., 2020,
Recent advances in experimental laboratory astrophysics for stellar astrophysics applications and future data needs
, Proceedings of the International Astronomical Union, Vol: 15, Pages: 220-228, ISSN: 1743-9213Accurate atomic data for line wavelengths, energy levels, line broadening such as hyperfine structure and isotope structure, and f-values, particularly for the line rich iron group elements, are needed for stellar astrophysics applications, and examples of recent measurements are given. These atomic data are essential for determination of elemental abundances in astronomical objects. With modern facilities, telescopes and spectrographs, access to underexplored regions (IR, UV, VUV), and improved stellar atmosphere models (3D, NLTE), and extremely large datasets, astronomers are tackling problems ranging from studying Galactic chemical evolution, to low mass stars and exoplanets. Such advances require improved accuracy and completeness of the atomic database for analyses of astrophysical spectra.
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Journal articleTeixeira JC, Folberth G, O'Connor FM, et al., 2020,
Coupling interactive fire with atmospheric composition and climatein the UK Earth System Model
<jats:p>Abstract. Fire constitutes a key process in the Earth system (ES) being driven by climate as well as affecting the climate by changing atmospheric composition and impacting the terrestrial carbon cycle. However, studies on the effects of fires on atmospheric composition, radiative forcing and climate have been limited to date, as the current generation of ES models (ESMs) do not include fully coupled fires. The aim of this work is the development and evaluation of a fully coupled fire-composition-climate ES model. For this, the INteractive Fires and Emissions algoRithm for Natural envirOnments (INFERNO) fire model is coupled to the atmosphere-only configuration of the UK’s Earth System Model (UKESM1). This fire-atmosphere interaction through atmospheric chemistry and aerosols allows for fire emissions to influence radiation, clouds, and generally weather, which can consequently influence the meteorological drivers of fire. Additionally, INFERNO is updated based on recent developments in the literature to improve the representation of human/economic factors in the anthropogenic ignition and suppression of fire. This work presents an assessment of the effects of interactive fire coupling on atmospheric composition and climate compared to the standard UKESM1 configuration that uses prescribed fire emissions. Results show a similar performance when using the fire-atmosphere coupling (the online version of the model) when compared to the offline UKESM1 that uses prescribed fire. The model can reproduce observed present day global fire emissions of carbon monoxide (CO) and aerosols, despite underestimating the global average burnt area. However, at a regional scale there is an overestimation of fire emissions over Africa due to the misrepresentation of the underlying vegetation types and an underestimation over Equatorial Asia due to a lack of representation of peat fires. Despite this, comparing model results with observations of CO column mixing rati
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Journal articleManners HA, Masters A, 2020,
The global distribution of ultra-low-frequency waves in Jupiter's magnetosphere
, Journal of Geophysical Research, Vol: 125, ISSN: 0148-0227Jupiter's giant magnetosphere is a complex system seldom in a configuration approximating steady state, and a clear picture of its governing dynamics remains elusive. Crucial to understanding how the magnetosphere behaves on a large scale are disturbances to the system on length‐scales comparable to the cavity, which are communicated by magnetohydrodynamic waves in the ultra‐low‐frequency band (<1 mHz). In this study we used magnetometer data from multiple spacecraft to perform the first global heritage survey of these waves in the magnetosphere. To map the equatorial region, we relied on the large local‐time coverage provided by the Galileo spacecraft. Flyby encounters performed by Voyager 1 & 2, Pioneer 10 & 11 and Ulysses provided local‐time coverage of the dawn sector. We found several hundred events where significant wave power was present, with periods spanning ~5‐60 min. The majority of events consisted of multiple superposed discrete periods. Periods at ~15, ~30 and ~40 min dominated the event‐averaged spectrum, consistent with the spectra of quasi‐periodic pulsations often reported in the literature. Most events were clustered in the outer magnetosphere close to the magnetopause at noon and dusk, suggesting that an external driving mechanism may dominate. The most energetic events occurred close to the planet, though more sporadically, indicating an accumulation of wave energy in the inner magnetosphere or infrequent impulsive drivers in the region. Our findings suggest that dynamics of the system at large scales is modulated by this diverse population of waves, which permeate the magnetosphere through several cavities and waveguides.
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Journal articleMüller D, Cyr OCS, Zouganelis I, et al., 2020,
The solar orbiter mission. science overview
, Astronomy & Astrophysics, Vol: 642, Pages: 1-31, ISSN: 0004-6361Aims. Solar Orbiter, the first mission of ESA’s Cosmic Vision 2015–2025 programme and a mission of international collaboration between ESA and NASA, will explore the Sun and heliosphere from close up and out of the ecliptic plane. It was launched on 10 February 2020 04:03 UTC from Cape Canaveral and aims to address key questions of solar and heliospheric physics pertaining to how the Sun creates and controls the Heliosphere, and why solar activity changes with time. To answer these, the mission carries six remote-sensing instruments to observe the Sun and the solar corona, and four in-situ instruments to measure the solar wind, energetic particles, and electromagnetic fields. In this paper, we describe the science objectives of the mission, and how these will be addressed by the joint observations of the instruments onboard.Methods. The paper first summarises the mission-level science objectives, followed by an overview of the spacecraft and payload. We report the observables and performance figures of each instrument, as well as the trajectory design. This is followed by a summary of the science operations concept. The paper concludes with a more detailed description of the science objectives.Results. Solar Orbiter will combine in-situ measurements in the heliosphere with high-resolution remote-sensing observations of the Sun to address fundamental questions of solar and heliospheric physics. The performance of the Solar Orbiter payload meets the requirements derived from the mission’s science objectives. Its science return will be augmented further by coordinated observations with other space missions and ground-based observatories.
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Journal articlePapini E, Cicone A, Piersanti M, et al., 2020,
Multidimensional Iterative Filtering: a new approach for investigating plasma turbulence in numerical simulations
, JOURNAL OF PLASMA PHYSICS, Vol: 86, ISSN: 0022-3778 -
Journal articleAlberti T, Laurenza M, Consolini G, et al., 2020,
On the Scaling Properties of Magnetic-field Fluctuations through the Inner Heliosphere
, ASTROPHYSICAL JOURNAL, Vol: 902, ISSN: 0004-637X- Author Web Link
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- Citations: 25
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Journal articleBeth A, Altwegg K, Balsiger H, et al., 2020,
ROSINA ion zoo at Comet 67P
, Astronomy and Astrophysics: a European journal, Vol: 642, Pages: 1-23, ISSN: 0004-6361Context. The Rosetta spacecraft escorted Comet 67P/Churyumov-Gerasimenko for 2 yr along its journey through the Solar System between 3.8 and 1.24 au. Thanks to the high resolution mass spectrometer on board Rosetta, the detailed ion composition within a coma has been accurately assessed in situ for the very first time.Aims. Previous cometary missions, such as Giotto, did not have the instrumental capabilities to identify the exact nature of the plasma in a coma because the mass resolution of the spectrometers onboard was too low to separate ion species with similar masses. In contrast, the Double Focusing Mass Spectrometer (DFMS), part of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis on board Rosetta (ROSINA), with its high mass resolution mode, outperformed all of them, revealing the diversity of cometary ions.Methods. We calibrated and analysed the set of spectra acquired by DFMS in ion mode from October 2014 to April 2016. In particular, we focused on the range from 13–39 u q−1. The high mass resolution of DFMS allows for accurate identifications of ions with quasi-similar masses, separating 13C+ from CH+, for instance.Results. We confirm the presence in situ of predicted cations at comets, such as CHm+ (m = 1−4), HnO+ (n = 1−3), O+, Na+, and several ionised and protonated molecules. Prior to Rosetta, only a fraction of them had been confirmed from Earth-based observations. In addition, we report for the first time the unambiguous presence of a molecular dication in the gas envelope of a Solar System body, namely CO2++.
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Journal articleHorbury TS, OBrien H, Carrasco Blazquez I, et al., 2020,
The Solar Orbiter magnetometer
, Astronomy & Astrophysics, Vol: 642, Pages: A9-A9, ISSN: 0004-6361The magnetometer instrument on the Solar Orbiter mission is designed to measure the magnetic field local to the spacecraft continuously for the entire mission duration. The need to characterise not only the background magnetic field but also its variations on scales from far above to well below the proton gyroscale result in challenging requirements on stability, precision, and noise, as well as magnetic and operational limitations on both the spacecraft and other instruments. The challenging vibration and thermal environment has led to significant development of the mechanical sensor design. The overall instrument design, performance, data products, and operational strategy are described.
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Journal articleZouganelis I, 2020,
The Solar Orbiter Science Activity Plan: translating solar and heliospheric physics questions into action
, Astronomy & Astrophysics, Vol: 642, Pages: 1-19, ISSN: 0004-6361Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand how the Sun produces and controls the heliosphere, filling the Solar System and driving the planetary environments. With six remote-sensing and four in-situ instrument suites, the coordination and planning of the operations are essential to address the following four top-level science questions: (1) What drives the solar wind and where does the coronal magnetic field originate?; (2) How do solar transients drive heliospheric variability?; (3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?; (4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? Maximising the mission’s science return requires considering the characteristics of each orbit, including the relative position of the spacecraft to Earth (affecting downlink rates), trajectory events (such as gravitational assist manoeuvres), and the phase of the solar activity cycle. Furthermore, since each orbit’s science telemetry will be downloaded over the course of the following orbit, science operations must be planned at mission level, rather than at the level of individual orbits. It is important to explore the way in which those science questions are translated into an actual plan of observations that fits into the mission, thus ensuring that no opportunities are missed. First, the overarching goals are broken down into specific, answerable questions along with the required observations and the so-called Science Activity Plan (SAP) is developed to achieve this. The SAP groups objectives that require similar observations into Solar Orbiter Observing Plans, resulting in a strategic, top-level view of the optimal opportunities for science observations during the mission lifetime. This allows for all four mission goals to be addressed. In this paper, w
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Journal articleMitchell JG, de Nolfo GA, Hill ME, et al., 2020,
Small Electron Events Observed by Parker Solar Probe/ISIS during Encounter 2
, ASTROPHYSICAL JOURNAL, Vol: 902, ISSN: 0004-637X- Author Web Link
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- Citations: 8
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Journal articleOwen CJ, Bruno R, Livi S, et al., 2020,
The Solar Orbiter Solar Wind Analyser (SWA) suite
, ASTRONOMY & ASTROPHYSICS, Vol: 642, ISSN: 0004-6361- Author Web Link
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- Citations: 113
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