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Journal articleHalekas JS, Whittlesey P, Larson DE, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X
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- Citations: 32
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Conference paperStephenson P, Altwegg K, Beth A, et al., 2022, , Publisher: Copernicus GmbH
<jats:p>&lt;p&gt;The Rosetta spacecraft escorted comet 67P/Churyumov-Gerasimenko for two years along its orbit, from Aug 2014 to Sep 2016, observing the evolution of the comet from a close perspective. The Rosetta Plasma Consortium (RPC) monitored the plasma environment at the spacecraft throughout the escort phase.&lt;/p&gt;&lt;p&gt;Cometary electrons are produced by ionization of the neutral gas coma. This occurs through photoionization by extreme ultraviolet photons, and through electron-impact ionization (EII) by collisions of energetic electrons with the coma. Far from perihelion, EII is, at times, more prevalent than photoionization (Galand et al., 2016; Heritier et al., 2018), but the EII frequency has not been assessed across the whole mission. The source of the cometary electrons, and the origin of the ionizing electrons is still unclear.&lt;/p&gt;&lt;p&gt;We have calculated the electron impact ionization (EII) frequency throughout the Rosetta mission and at its location from measurements of RPC&amp;#8217;s Ion and Electron Sensor (RPC/IES). EII ionization is confirmed as the dominant source of cometary electrons and ions when far from perihelion but is much more variable than photoionization. We compare the EII frequency with properties of the neutral coma and cometary plasma to identify key drivers of the energetic electron population. The EII frequency is structured by outgassing rate and magnetic field strength.&lt;/p&gt;&lt;p&gt;The first 3D collision model of electrons at a comet (Stephenson et al. 2022) is also utilised to assess the origin of electrons within the coma. The model uses self-consistently calculated electric and magnetic fields from a fully-kinetic and collisionless Particle-in-Cell model (Deca et al. 2017, 2019)as an input. The modelling approach confirms cometary electrons are produced by impacts of energetic e
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Journal articleTigik SF, Vaivads A, Malaspina DM, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 936, ISSN: 0004-637X
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- Citations: 9
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Journal articleGraham J, Hannides A, Mamnun N, et al., 2022, , Earth and Space Science, Vol: 9
This article is composed of three independent commentaries of how “Integrated, Coordinated, Open, and Networked” (ICON), as well as “Findable, Accessible, Interoperable, and Reusable” (FAIR; under the umbrella of “Open” from ICON), principles are currently embedded in ocean sciences, and what are the opportunities and challenges by adopting them. Each commentary focuses on a different perspective as follows: (a) field sampling and experimentation to remote-sensing and autonomous observations; (b) global collaboration, technology transfer and application, reproducibility, and data sharing and infrastructure; (c) increasing diversity and broadening participation in ocean sciences. Overall, there is a consensus that ocean sciences is well-advanced in adopting many of the Integrated, Coordinated, Open, and Networked-Findable, Accessible, Interoperable, and Reusable (ICON-FAIR) principles regarding (a and b), although there are still plenty of opportunities to develop further by, for instance, making broader use of data-of-opportunity and citizen science, improving efforts toward standardized data organization and avoiding data fragmentation, and increasing training activities to implement good practices. On the other hand, fostering diversity, and broadening participation in ocean sciences is still in its infancy. Actions are needed to overcome under-representation of women and other marginalized groups, create opportunities for early-career scientists, and build bridges to support scientists from low-income countries. We recognize that adopting ICON-FAIR principles comes with high costs and efforts, but it has strong potential to develop ocean sciences in many aspects.
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Journal articleAizawa S, Persson M, Menez T, et al., 2022, , PLANETARY AND SPACE SCIENCE, Vol: 218, ISSN: 0032-0633
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- Citations: 3
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Journal articleDing M, Pickering JC, 2022, , JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER, Vol: 288, ISSN: 0022-4073
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- Citations: 3
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Journal articleFranci L, Papini E, Del Sarto D, et al., 2022, , UNIVERSE, Vol: 8
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- Citations: 3
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Journal articleTeoh R, Schumann U, Gryspeerdt E, et al., 2022, , Atmospheric Chemistry and Physics, Vol: 22, Pages: 10919-10935, ISSN: 1680-7316
Around 5 % of anthropogenic radiative forcing (RF) is attributed to aviation CO2 and non-CO2 impacts. This paper quantifies aviation emissions and contrail climate forcing in the North Atlantic, one of the world's busiest air traffic corridors, over 5 years. Between 2016 and 2019, growth in CO2 (+3.13 % yr−1) and nitrogen oxide emissions (+4.5 % yr−1) outpaced increases in flight distance (+3.05 % yr−1). Over the same period, the annual mean contrail cirrus net RF (204–280 mW m−2) showed significant inter-annual variability caused by variations in meteorology. Responses to COVID-19 caused significant reductions in flight distance travelled (−66 %), CO2 emissions (−71 %) and the contrail net RF (−66 %) compared with the prior 1-year period. Around 12 % of all flights in this region cause 80 % of the annual contrail energy forcing, and the factors associated with strongly warming/cooling contrails include seasonal changes in meteorology and radiation, time of day, background cloud fields, and engine-specific non-volatile particulate matter (nvPM) emissions. Strongly warming contrails in this region are generally formed in wintertime, close to the tropopause, between 15:00 and 04:00 UTC, and above low-level clouds. The most strongly cooling contrails occur in the spring, in the upper troposphere, between 06:00 and 15:00 UTC, and without lower-level clouds. Uncertainty in the contrail cirrus net RF (216–238 mW m−2) arising from meteorology in 2019 is smaller than the inter-annual variability. The contrail RF estimates are most sensitive to the humidity fields, followed by nvPM emissions and aircraft mass assumptions. This longitudinal evaluation of aviation contrail impacts contributes a quantified understanding of inter-annual variability and informs strategies for contrail mitigation.
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Journal articleSharan S, Langlais B, Amit H, et al., 2022, , GEOPHYSICAL RESEARCH LETTERS, Vol: 49, ISSN: 0094-8276
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- Citations: 13
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Journal articleWang S, Toumi R, 2022, , Sci Rep, Vol: 12
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Journal articleRasca AP, Farrell WM, Whittlesey PL, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 935, ISSN: 0004-637X
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- Citations: 4
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Journal articleTelloni D, Zank GP, Sorriso-Valvo L, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 935, ISSN: 0004-637X
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- Citations: 12
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Journal articleSioulas N, Huang Z, Velli M, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 934, ISSN: 0004-637X
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- Citations: 20
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Journal articleShi C, Panasenco O, Velli M, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 934, ISSN: 0004-637X
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- Citations: 25
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Journal articleZhao L-L, Zank GP, Adhikari L, et al., 2022, , ASTROPHYSICAL JOURNAL LETTERS, Vol: 934, ISSN: 2041-8205
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- Citations: 25
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Journal articleErgun RE, Pathak N, Usanova ME, et al., 2022, , ASTROPHYSICAL JOURNAL LETTERS, Vol: 935, ISSN: 2041-8205
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- Citations: 19
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Journal articleSulaiman A, Mauk B, Szalay J, et al., 2022, , Journal of Geophysical Research: Space Physics, Vol: 127, ISSN: 2169-9380
The Juno spacecraft's polar orbits have enabled direct sampling of Jupiter's low-altitude auroral field lines. While various data sets have identified unique features over Jupiter's main aurora, they are yet to be analyzed altogether to determine how they can be reconciled and fit into the bigger picture of Jupiter's auroral generation mechanisms. Jupiter's main aurora has been classified into distinct “zones”, based on repeatable signatures found in energetic electron and proton spectra. We combine fields, particles, and plasma wave data sets to analyze Zone-I and Zone-II, which are suggested to carry upward and downward field-aligned currents, respectively. We find Zone-I to have well-defined boundaries across all data sets. H+ and/or H3+ cyclotron waves are commonly observed in Zone-I in the presence of energetic upward H+ beams and downward energetic electron beams. Zone-II, on the other hand, does not have a clear poleward boundary with the polar cap, and its signatures are more sporadic. Large-amplitude solitary waves, which are reminiscent of those ubiquitous in Earth's downward current region, are a key feature of Zone-II. Alfvénic fluctuations are most prominent in the diffuse aurora and are repeatedly found to diminish in Zone-I and Zone-II, likely due to dissipation, at higher altitudes, to energize auroral electrons. Finally, we identify significant electron density depletions, by up to 2 orders of magnitude, in Zone-I, and discuss their important implications for the development of parallel potentials, Alfvénic dissipation, and radio wave generation.
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Journal articleClear CP, Pickering JC, Nave G, et al., 2022, , The Astrophysical Journal Supplement Series, Vol: 261, Pages: 35-35, ISSN: 0067-0049
High-resolution spectra of singly ionized nickel (Ni ii) have been recorded using Fourier transform spectroscopy in the region 143–5555 nm (1800–70,000 cm−1) with continuous, nickel–helium hollow cathode discharge sources. An extensive analysis of identified Ni ii lines resulted in the confirmation and revision of 283 previously reported energy levels, from the ground state up to the 3d8(ML)6s subconfigurations. Typical energy-level uncertainties are a few thousandths of a cm−1, representing at least an order-of-magnitude reduction in uncertainty with respect to previous measurements. Twenty-five new energy levels have now been established and are reported here for the first time. Eigenvector compositions of the energy levels have been calculated using the orthogonal operator method. In total, 159 even and 149 odd energy levels and 1424 classified line wavelengths of Ni ii are reported and will enable more accurate and reliable analyses of Ni ii in astrophysical spectra.
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Journal articlePark C, Shin S-W, Kim G, et al., 2022, , RENEWABLE ENERGY, Vol: 195, Pages: 1480-1480, ISSN: 0960-1481
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- Citations: 1
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Journal articleBrunmayr AS, Graven H, 2022,
<jats:p>Chanca et al. (2022) construct radiocarbon (14C) distributions forcompartmental ecosystem models and compare them to the variability ofmeasured 14C data for soil respiration. However, their 14C distributionsdo not represent a measurable quantity and may not be used to draw anyconclusions on the variability of 14C measurements.</jats:p>
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Journal articleSchwartz SJ, Goodrich KA, III LBW, et al., 2022,
<jats:p>Collisionless shocks in astrophysical plasmas are importantthermalizers, converting some of the incident flow energy into thermalenergy, and non-thermalizers, partitioning that energy in unequal waysto different particle species, sub-populations thereof, and fieldcomponents. This partition problem, or equivalently the shock equationof state, lies at the heart of shock physics. Here we employsystematically a framework to capture all the incident and downstreamenergy fluxes at two example traversals of the Earth's bow shock by theMagnetospheric Multiscale Mission. Here and traditionally such data hasto be augmented by information from other spacecraft, e.g., to providemore accurate measurements of the cold solar wind beam. With some careand fortuitous choices, the energy fluxes are constant, includinginstantaneous measurements through the shock layer. The dominantincident proton ram energy is converted primarily into downstream protonenthalpy flux, the majority of which is actually carried by a smallfraction of suprathermal protons. Fluctuations include both real andinstrumental effects. Separating these, resolving the solar wind beam,and other considerations point the way to a dedicated mission to solvethis energy partition problem across a full range of plasma and shockconditions.</jats:p>
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Journal articleGraven H, Keeling R, Xu X, 2022, , NATURE, Vol: 607, Pages: 449-449, ISSN: 0028-0836
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- Citations: 1
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Journal articleFargette N, Lavraud B, Rouillard AP, et al., 2022, , ASTRONOMY & ASTROPHYSICS, Vol: 663, ISSN: 0004-6361
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- Citations: 21
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Journal articleKilpua EKJ, Good SW, Ala-Lahti M, et al., 2022, , ASTRONOMY & ASTROPHYSICS, Vol: 663, ISSN: 0004-6361
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- Citations: 9
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Journal articleDavies EE, Winslow RM, Scolini C, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 933, ISSN: 0004-637X
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- Citations: 4
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Journal articleTrotta D, Pecora F, Settino A, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 933, ISSN: 0004-637X
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- Citations: 7
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Journal articleTsui EYL, Toumi R, 2022, , Quarterly Journal of the Royal Meteorological Society, Vol: 148, Pages: 2102-2117, ISSN: 0035-9009
The SubNiño4 index based on the subsurface potential temperature around the thermocline beneath the west Pacific warm pool, the Niño 4 region, is examined as a long-range indicator of the surface El Niño–Southern Oscillation (ENSO) and ENSO-driven atmospheric response. The SubNiño4 index captures the evolution of subsurface ocean heat content between the El Niño and La Niña phases of the ENSO cycle, allowing it to serve as a long-range indicator of surface ENSO and hence also many ENSO-driven atmospheric anomalies. The SubNiño4 index has more temporally stable correlations with Niño 3.4 than the widely used western equatorial Pacific warm-water volume indicator. For a lead time of the order of 12 months, Niño 3.4 correlations afforded by the lead observed SubNiño4 index become similar to and can exceed those produced by typical dynamical ENSO predictions. The value and viability of the SubNiño4 index as a simple statistical long-range indicator of ENSO-driven atmospheric response is shown for regional precipitation anomalies throughout the Tropics and fires in Continental and Maritime Southeast Asia.
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Journal articleGangopadhyay A, Seshadri AK, Sparks NJ, et al., 2022, , Renewable Energy, Vol: 194, Pages: 926-937, ISSN: 0960-1481
Increasing the share of weather-dependent renewables in the electricity grid is essential to deeply decarbonize the electricity system. Wind and solar “droughts” or low generation days can severely impact grid stability in a renewable-rich grid. This paper analyzes for the first time wind, solar, and hybrid energy-droughts in India using a stochastic weather generator. Available literature analyze the observational data that is of limited duration (30–40 years). Therefore, discussion of low-probability high-impact renewable energy-droughts that have long return periods (in the range of 30 years) is limited in the literature. The present study seeks to address this research gap by exploring the risk of wind, solar, and wind-solar powered energy-droughts based on simulated long time series (5000 years). It is found that the weather generator captures mean, seasonality, and correlation between wind speed and solar irradiance and is therefore used to estimate return periods of extreme wind and solar-droughts. Our analysis shows that wind-droughts are more intense than solar-droughts in India. We examine the role that wind-solar hybridization can play in offsetting low wind energy episodes. The benefits of hybridization are regionally dependent. In South India, hybrid plants have advantages over either wind or solar plants alone. In comparison, for Rajasthan, the benefits of hybridization are limited. When one of the regions (South India or Rajasthan) has a renewable drought, the other region has only a 10% probability of having a similar drought. Our findings highlight the need for having robust inter-regional grid connections to mitigate regional level renewable droughts.
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Journal articleGryspeerdt E, McCoy DT, Crosbie E, et al., 2022, , Atmospheric Measurement Techniques, Vol: 15, Pages: 3875-3892, ISSN: 1867-1381
Cloud droplet number concentration (Nd) is of central importance to observation-based estimates of aerosol indirect effects, being used to quantify both the cloud sensitivity to aerosol and the base state of the cloud. However, the derivation of Nd from satellite data depends on a number of assumptions about the cloud and the accuracy of the retrievals of the cloud properties from which it is derived, making it prone to systematic biases.A number of sampling strategies have been proposed to address these biases by selecting the most accurate Nd retrievals in the satellite data. This work compares the impact of these strategies on the accuracy of the satellite retrieved Nd, using a selection of in situ measurements. In stratocumulus regions, the MODIS Nd retrieval is able to achieve a high precision (r2 of 0.5–0.8). This is lower in other cloud regimes but can be increased by appropriate sampling choices. Although the Nd sampling can have significant effects on the Nd climatology, it produces only a 20 % variation in the implied radiative forcing from aerosol–cloud interactions, with the choice of aerosol proxy driving the overall uncertainty. The results are summarised into recommendations for using MODIS Nd products and appropriate sampling.
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Journal articleMcManus MD, Verniero J, Bale SD, et al., 2022, , ASTROPHYSICAL JOURNAL, Vol: 933, ISSN: 0004-637X
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- Citations: 15
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