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  • Journal article
    Ben-Yami M, Oetjen H, Brindley H, Cossich W, Lajas D, Maestri T, Magurno D, Raspollini P, Sgheri L, Warwick Let al., 2022,

    Emissivity retrievals with FORUM's end-to-end simulator: challenges and recommendations

    , Atmospheric Measurement Techniques, Vol: 15, Pages: 1755-1777, ISSN: 1867-1381

    Spectral emissivity is a key property of the Earth's surface, of which only very few measurements exist so far in the far-infrared (FIR) spectral region, even though recent work has shown that the FIR is important for accurate modelling of the global climate. The European Space Agency's 9th Earth Explorer, FORUM (Far-infrared Outgoing Radiation Understanding and Monitoring) will provide the first global spectrally resolved measurements of the Earth's top-of-the-atmosphere (TOA) spectrum in the FIR. In clear-sky conditions with low water vapour content, these measurements will provide a unique opportunity to retrieve spectrally resolved FIR surface emissivity. In preparation for the FORUM mission with an expected launch in 2027, this study takes the first steps towards the development of an operational emissivity retrieval for FORUM by investigating the sensitivity of the emissivity product of a full spectrum optimal estimation retrieval method to different physical and operational parameters. The tool used for the sensitivity tests is the FORUM mission's end-to-end simulator. These tests show that the spectral emissivity of most surface types can be retrieved for dry scenes in the 350–600 cm−1 region, with an absolute uncertainty ranging from 0.005 to 0.01. In addition, the quality of the retrieval is quantified with respect to the precipitable water vapour content of the scene, and the uncertainty caused by the correlation of emissivity with surface temperature is investigated. Based on these investigations, a road map is recommended for the development of the operational emissivity product.
  • Journal article
    Saboya E, Zazzeri G, Graven H, Manning AJ, Michel SEet al., 2022,

    Continuous CH4 and delta(CH4)-C-13 measurements in London demonstrate under-reported natural gas leakage

    , Atmospheric Chemistry and Physics, Vol: 22, Pages: 3595-3613, ISSN: 1680-7316

    Top-down greenhouse gas measurements can be used to independently assess the accuracy of bottom-up emission estimates. We report atmospheric methane (CH4) mole fractions and δ13CH4 measurements from Imperial College London from early 2018 onwards using a Picarro G2201-i analyser. Measurements from March 2018 to October 2020 were compared to simulations of CH4 mole fractions and δ13CH4 produced using the NAME (Numerical Atmospheric-dispersion Modelling Environment) dispersion model coupled with the UK National Atmospheric Emissions Inventory, UK NAEI, and a global inventory, the Emissions Database for Global Atmospheric Research (EDGAR), with model spatial resolutions of ∼ 2, ∼ 10, and ∼ 25 km. Simulation–measurement comparisons are used to evaluate London emissions and the source apportionment in the global (EDGAR) and UK national (NAEI) emission inventories. Observed mole fractions were underestimated by 30 %–35 % in the NAEI simulations. In contrast, a good correspondence between observations and EDGAR simulations was seen. There was no correlation between the measured and simulated δ13CH4 values for either NAEI or EDGAR, however, suggesting the inventories' sectoral attributions are incorrect. On average, natural gas sources accounted for 20 %–28 % of the above background CH4 in the NAEI simulations and only 6 %–9 % in the EDGAR simulations. In contrast, nearly 84 % of isotopic source values calculated by Keeling plot analysis (using measurement data from the afternoon) of individual pollution events were higher than −45 ‰, suggesting the primary CH4 sources in London are actually natural gas leaks. The simulation–observation comparison of CH4 mole fractions suggests that total emissions in London are much higher than the NAEI estimate (0.04 Tg CH4 yr−1) but close to, or slightly lo
  • Journal article
    Reville V, Fargette N, Rouillard AP, Lavraud B, Velli M, Strugarek A, Parenti S, Brun AS, Shi C, Kouloumvakos A, Poirier N, Pinto RF, Louarn P, Fedorov A, Owen CJ, Genot V, Horbury TS, Laker R, O'Brien H, Angelini V, Fauchon-Jones E, Kasper JCet al., 2022,

    Flux rope and dynamics of the heliospheric current sheet Study of the Parker Solar Probe and Solar Orbiter conjunction of June 2020

    , Astronomy and Astrophysics: a European journal, Vol: 659, Pages: 1-14, ISSN: 0004-6361

    Context. Solar Orbiter and Parker Solar Probe jointly observed the solar wind for the first time in June 2020, capturing data from very different solar wind streams: calm, Alfvénic wind and also highly dynamic large-scale structures.Context. Our aim is to understand the origin and characteristics of the highly dynamic solar wind observed by the two probes, particularly in the vicinity of the heliospheric current sheet (HCS).Methods. We analyzed the plasma data obtained by Parker Solar Probe and Solar Orbiter in situ during the month of June 2020. We used the Alfvén-wave turbulence magnetohydrodynamic solar wind model WindPredict-AW and we performed two 3D simulations based on ADAPT solar magnetograms for this period.Results. We show that the dynamic regions measured by both spacecraft are pervaded by flux ropes close to the HCS. These flux ropes are also present in the simulations, forming at the tip of helmet streamers, that is, at the base of the heliospheric current sheet. The formation mechanism involves a pressure-driven instability followed by a fast tearing reconnection process. We further characterize the 3D spatial structure of helmet streamer born flux ropes, which appears in the simulations to be related to the network of quasi-separatrices.
  • Journal article
    Ukhorskiy AY, Sorathia KA, Merkin VG, Crabtree C, Fletcher AC, Malaspina DM, Schwartz SJet al., 2022,

    Cross-scale energy cascade powered by magnetospheric convection

    , SCIENTIFIC REPORTS, Vol: 12, ISSN: 2045-2322
  • Journal article
    Larosa A, Dudok de Wit T, Krasnoselskikh V, Bale SD, Agapitov O, Bonnell J, Froment C, Goetz K, Harvey P, Halekas J, Kretzschmar M, MacDowall R, Malaspina DM, Moncuquet M, Niehof J, Pulupa M, Revillet Cet al., 2022,

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

    , ASTROPHYSICAL JOURNAL, Vol: 927, ISSN: 0004-637X
  • Journal article
    Sioulas N, Velli M, Chhiber R, Vlahos L, Matthaeus WH, Bandyopadhyay R, Cuesta ME, Shi C, Bowen TA, Qudsi RA, Stevens ML, Bale SDet al., 2022,

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

    , ASTROPHYSICAL JOURNAL, Vol: 927, ISSN: 0004-637X
    • Cite
    • Citations: 16
  • Journal article
    Reville V, Velli M, Panasenco O, Tenerani A, Shi C, Badman ST, Bale SD, Kasper JC, Stevens ML, Korreck KE, Bonnell JW, Case AW, Dudok de Wit T, Goetz K, Harvey PR, Larson DE, Livi R, Malaspina DM, MacDowall RJ, Pulupa M, Whittlesey PLet al., 2022,

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

    , ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, Vol: 259, ISSN: 0067-0049
  • Journal article
    Mozer FS, Bale SD, Cattell CA, Halekas J, Vasko IY, Verniero JL, Kellogg PJet al., 2022,

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

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 927, ISSN: 2041-8205
    • Cite
    • Citations: 13
  • Journal article
    Desai M, Mitchell DG, McComas DJ, Drake JF, Phan T, Szalay JR, Roelof EC, Giacalone J, Hill ME, Christian ER, Schwadron NA, McNutt RL, Wiedenbeck ME, Joyce C, Cohen CMS, Davis AJ, Krimigis SM, Leske RA, Matthaeus WH, Malandraki O, Mewaldt RA, Labrador A, Stone EC, Bale SD, Verniero J, Rahmati A, Whittlesey P, Livi R, Larson D, Pulupa M, MacDowall RJ, Niehof JT, Kasper JC, Horbury TSet al., 2022,

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

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

    We present observations of ≳10–100 keV nucleon−1 suprathermal (ST) H, He, O, and Fe ions associated with crossings of the heliospheric current sheet (HCS) at radial distances of <0.1 au from the Sun. Our key findings are as follows: (1) very few heavy ions are detected during the first full crossing, the heavy-ion intensities are reduced during the second partial crossing and peak just after the second crossing; (2) ion arrival times exhibit no velocity dispersion; (3) He pitch-angle distributions track the magnetic field polarity reversal and show up to ∼10:1 anti-sunward, field-aligned flows and beams closer to the HCS that become nearly isotropic farther from the HCS; (4) the He spectrum steepens either side of the HCS, and the He, O, and Fe spectra exhibit power laws of the form ∼E−4–E6; and (5) maximum energies EX increase with the ion's charge-to-mass (Q/M) ratio as ${E}_{X}/{E}_{H}\propto {({Q}_{X}/{M}_{X})}^{\delta }$, where δ ∼ 0.65–0.76, assuming that the average Q states are similar to those measured in gradual and impulsive solar energetic particle events at 1 au. The absence of velocity dispersion in combination with strong field-aligned anisotropies closer to the HCS appears to rule out solar flares and near-Sun coronal-mass-ejection-driven shocks. These new observations present challenges not only for mechanisms that employ direct parallel electric fields and organize maximum energies according to E/Q but also for local diffusive and magnetic-reconnection-driven acceleration models. Reevaluation of our current understanding of the production and transport of energetic ions is necessary to understand this near-solar, current-sheet-associated population of ST ions.
  • Journal article
    Wang S, Toumi R, 2022,

    On the intensity decay of tropical cyclones before landfall

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

    It remains unclear how tropical cyclones (TCs) decay from their ocean lifetime maximum intensity (LMI) to landfall intensity (LI), yet this stage is of fundamental importance governing the socio-economic impact of TCs. Here we show that TCs decay on average by 25% from LMI to LI. A logistic decay model of energy production by ocean enthalpy input and surface dissipation by frictional drag, can physically connect the LMI to LI. The logistic model fits the observed intensity decay as well as an empirically exponential decay does, but with a clear physical foundation. The distance between locations of LMI and TC landfall is found to dominate the variability of the decay from the LMI to LI, whereas environmental conditions are generally less important. A major TC at landfall typically has a very large LMI close to land. The LMI depends on the heating by ocean warming, but the LMI location is also important to future landfall TC intensity changes which are of socio-economic importance.
  • Journal article
    Trofimov H, Post P, Gryspeerdt E, Toll Vet al., 2022,

    Meteorological conditions favorable for strong anthropogenic aerosol impacts on clouds

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

    Ship-track-like polluted cloud tracks provide a direct way to study aerosol-cloud interactions. Here, we study environmental conditions favorable for pollution tracks' formation. We study polluted cloud tracks forming downwind of localized anthropogenic air pollution hot spots of Norilsk and Cherepovets in Russia and Thompson in Canada. Polluted cloud tracks form on 20%–37% of days with liquid-phase clouds. The large-scale atmospheric circulation largely determines the occurrence of track-favoring conditions. Tracks tend to form in clean and thin clouds under stable and dry conditions that are more often associated with anticyclonic large-scale flow in the studied locations.
  • Journal article
    Li D, Feng J, Zhu Y, Staneva J, Qi J, Behrens A, Lee D, Min S-K, Yin Bet al., 2022,

    Dynamical Projections of the Mean and Extreme Wave Climate in the Bohai Sea, Yellow Sea and East China Sea

    , FRONTIERS IN MARINE SCIENCE, Vol: 9
  • Journal article
    Chen L-J, Halekas J, Wang S, DiBraccio GA, Romanelli N, Ng J, Russell CT, Schwartz SJ, Sibeck DG, Farrell W, Pollock C, Gershman D, Giles B, Collado-Vega YMet al., 2022,

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

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 49, ISSN: 0094-8276
  • Journal article
    Mozer FS, Bale SD, Kellogg PJ, Larson D, Livi R, Romeo Oet al., 2022,

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

    , ASTROPHYSICAL JOURNAL, Vol: 926, ISSN: 0004-637X
  • Journal article
    Agapitov V, Drake JF, Swisdak M, Bale SD, Horbury TS, Kasper JC, MacDowall RJ, Mozer FS, Phan TD, Pulupa M, Raouafi E, Velli Met al., 2022,

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

    , ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X
    • Cite
    • Citations: 19
  • Journal article
    Bandyopadhyay R, Matthaeus WH, McComas DJ, Chhiber R, Usmanov A, Huang J, Livi R, Larson DE, Kasper JC, Case AW, Stevens M, Whittlesey P, Romeo OM, Bale SD, Bonnell JW, de Wit TD, Goetz K, Harvey PR, MacDowall RJ, Malaspina DM, Pulupa Met al., 2022,

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

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
    • Cite
    • Citations: 46
  • Journal article
    Rodriguez L, Barnes D, Hosteaux S, Davies JA, Willems S, Pant V, Harrison RA, Berghmans D, Bothmer V, Eastwood JP, Gallagher PT, Kilpua EKJ, Magdalenic J, Mierla M, Mostl C, Rouillard AP, Odstrcil D, Poedts Set al., 2022,

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

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

    We present the results of a comparative study between automatic and manually compiled coronal mass ejection (CME) catalogues based on observations from the Heliospheric Imagers (HIs) onboard NASA’s Solar Terrestrial Relations Observatory (STEREO) spacecraft. Using the Computer Aided CME Tracking software (CACTus), CMEs are identified in HI data using an automatic feature-detection algorithm, while the Heliospheric Imagers Catalogue (HICAT) includes CMEs that are detected by visual inspection of HI images. Both catalogues were compiled as part of the EU FP7 Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project (www.helcats-fp7.eu). We compare observational parameters of the CMEs from CACTus to those listed in HICAT, such as CME frequency, position angle (PA), and PA-width. We also compare CACTus-derived speeds to speeds derived from applying geometric modelling to the majority of the HICAT CMEs, the results of which are listed in the HELCATS Heliospheric Imagers Geometric Catalogue (HIGeoCAT). We find that both CACTus and HICAT catalogues contain a similar number of events when we exclude events narrower than 20∘, which are not included in the HICAT catalogue but are found to be identified by CACTus. PA-distributions are strongly peaked around 90∘ and 270∘, with a slightly larger CME frequency northwards of the equatorial plane (particularly for the STEREO-A versions of both catalogues). The CME PA-widths in both HICAT and CACTus catalogues peak at approximately 60∘. Manually derived speeds from HIGeoCAT and automatically derived speeds by CACTus correlate well for values lower than 1000 km s−1, in particular when CMEs are propagating close to the plane of the sky.
  • Journal article
    Getachew T, McComas DJ, Joyce CJ, Palmerio E, Christian ER, Cohen CMS, Desai M, Giacalone J, Hill ME, Matthaeus WH, McNutt RL, Mitchell DG, Mitchell JG, Rankin JS, Roelof EC, Schwadron NA, Szalay JR, Zank GP, Zhao L-L, Lynch BJ, Phan TD, Bale SD, Whittlesey PL, Kasper JCet al., 2022,

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

    , ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X
  • Journal article
    Archer M, Southwood D, Hartinger M, Rastaetter L, Wright Aet al., 2022,

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

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

    System-scale magnetohydrodynamic (MHD) waves within Earth's magnetosphere are often understood theoretically using box models. While these have been highly instructive in understanding many fundamental features of the various wave modes present, they neglect the complexities of geospace such as the inhomogeneities and curvilinear geometries present. Here, we show global MHD simulations of resonant waves impulsively excited by a solar wind pressure pulse. Although many aspects of the surface, fast magnetosonic (cavity/waveguide), and Alfvén modes present agree with the box and axially symmetric dipole models, we find some predictions for large-scale waves are significantly altered in a realistic magnetosphere. The radial ordering of fast mode turning points and Alfvén resonant locations may be reversed even with monotonic wave speeds. Additional nodes along field lines that are not present in the displacement/velocity occur in both the perpendicular and compressional components of the magnetic field. Close to the magnetopause, the perpendicular oscillations of the magnetic field have the opposite handedness to the velocity. Finally, widely used detection techniques for standing waves, both across and along the field, can fail to identify their presence. We explain how all these features arise from the MHD equations when accounting for a non-uniform background field and propose modified methods that might be applied to spacecraft observations.
  • Journal article
    van der Holst B, Huang J, Sachdeva N, Kasper JC, Manchester WB, Borovikov D, Chandran BDG, Case AW, Korreck KE, Larson D, Livi R, Stevens M, Whittlesey P, Bale SD, Pulupa M, Malaspina DM, Bonnell JW, Harvey PR, Goetz K, MacDowall RJet al., 2022,

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

    , ASTROPHYSICAL JOURNAL, Vol: 925, ISSN: 0004-637X
    • Cite
    • Citations: 28
  • Journal article
    Mostafavi P, Allen RC, McManus MD, Ho GC, Raouafi NE, Larson DE, Kasper JC, Bale SDet al., 2022,

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

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
    • Cite
    • Citations: 35
  • Journal article
    Zank GP, Zhao L-L, Adhikari L, Telloni D, Kasper JC, Stevens M, Rahmati A, Bale SDet al., 2022,

    Turbulence in the Sub-Alfvenic Solar Wind

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
    • Cite
    • Citations: 52
  • Journal article
    Vasko IY, Alimov K, Phan T, Bale SD, Mozer FS, Artemyev Aet al., 2022,

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

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
    • Cite
    • Citations: 38
  • Journal article
    Shi C, Zhao J, Malaspina DM, Bale SD, Dong X, Wang T, Wu Det al., 2022,

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

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 926, ISSN: 2041-8205
  • Journal article
    Park C, Shin S-W, Kim G, Cha D-H, Min S-K, Lee D, Byun Y-H, Kim J-Uet al., 2022,

    What determines future changes in photovoltaic potential over East Asia?

    , RENEWABLE ENERGY, Vol: 185, Pages: 338-347, ISSN: 0960-1481
  • Journal article
    Shebanits O, Wahlund J-E, Waite JH, Dougherty MKet al., 2022,

    Conductivities of Titan's Dusty Ionosphere

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380
  • Journal article
    Simon Wedlund CL, Volwerk M, Beth A, Mazelle C, Moestl C, Halekas JS, Gruesbeck JR, Rojas-Castillo Det al., 2021,

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

    , Journal of Geophysical Research: Space Physics, ISSN: 2169-9380
  • Journal article
    Archer M, Waters C, Dewan S, Foster S, Portas Aet al., 2022,

    GC Insights: Space sector careers resources need a greater diversity of roles

    <jats:p>Abstract. Educational research highlights that improved careers education is needed to increase participation in STEM. Current careers resources concerning the space sector, however, are found to perhaps not best reflect the diversity of roles present and may in fact perpetuate misconceptions about the usefulness of science. We, therefore, compile a more diverse set of space-related jobs, which will be used in the development of a new space careers resource.</jats:p>
  • Journal article
    Christensen MW, Gettelman A, Cermak J, Dagan G, Diamond M, Douglas A, Feingold G, Glassmeier F, Goren T, Grosvenor DP, Gryspeerdt E, Kahn R, Li Z, Ma P-L, Malavelle F, McCoy IL, McCoy DT, McFarquhar G, Mulmenstadt J, Pal S, Possner A, Povey A, Quaas J, Rosenfeld D, Schmidt A, Schroedner R, Sorooshian A, Stier P, Toll V, Watson-Parris D, Wood R, Yang M, Yuan Tet al., 2022,

    Opportunistic experiments to constrain aerosol effective radiative forcing

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

    Aerosol–cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be challenging when meteorological variability also drives both aerosol and cloud changes independently. Natural and anthropogenic aerosol perturbations from well-defined sources provide “opportunistic experiments” (also known as natural experiments) to investigate ACI in cases where causality may be more confidently inferred. These perturbations cover a wide range of locations and spatiotemporal scales, including point sources such as volcanic eruptions or industrial sources, plumes from biomass burning or forest fires, and tracks from individual ships or shipping corridors. We review the different experimental conditions and conduct a synthesis of the available satellite datasets and field campaigns to place these opportunistic experiments on a common footing, facilitating new insights and a clearer understanding of key uncertainties in aerosol radiative forcing. Cloud albedo perturbations are strongly sensitive to background meteorological conditions. Strong liquid water path increases due to aerosol perturbations are largely ruled out by averaging across experiments. Opportunistic experiments have significantly improved process-level understanding of ACI, but it remains unclear how reliably the relationships found can be scaled to the global level, thus demonstrating a need for deeper investigation in order to improve assessments of aerosol radiative forcing and climate change.
  • Journal article
    Chadney JM, Koskinen TT, Hu X, Galand M, Lavvas P, Unruh Y, Serigano J, Hörst SM, Yelle RVet al., 2022,

    Energy deposition in Saturn's equatorial upper atmosphere

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

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

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