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Journal articleTrencham NE, Czaja A, Haigh JD, 2024,
The Impact of Oceanic Feedbacks on Stratosphere-Troposphere Coupling in an Idealized Model
, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, Vol: 129, ISSN: 2169-897X -
Journal articleGrimmich N, Plaschke F, Grison B, et al., 2024,
The Cluster spacecrafts' view of the motion of the high-latitude magnetopause
, Annales Geophysicae: atmospheres, hydrospheres and space sciences, Vol: 42, Pages: 371-394, ISSN: 0992-7689The magnetopause is the boundary between the interplanetary magnetic field and the terrestrial magnetic field. It is influenced by different solar-wind conditions, which lead to a change in the shape and location of the magnetopause. The interaction between the solar wind and the magnetosphere can be studied from in situ spacecraft observations. Many studies focus on the equatorial plane as this is where recent spacecraft constellations such as THEMIS or MMS operate. However, to fully capture the interaction, it is important to study the high-latitude regions as well. Since the Cluster spacecraft operate in a highly elliptical polar orbit, the spacecraft often pass through the magnetopause at high latitudes. This allows us to collect a dataset of high-latitude magnetopause crossings and to study magnetopause motion in this region, as well as deviations from established magnetopause models. We use multi-spacecraft analysis tools to investigate the direction of the magnetopause motion in the high latitudes and to compare the occurrence of crossings at different locations with the result in the equatorial plane. We find that the high-latitude magnetopause motion is generally consistent with previously reported values and seems to be more often associated with a closed magnetopause boundary. We show that, on average, the magnetopause moves faster inwards than outwards. Furthermore, the occurrence of magnetopause positions beyond those predicted by the Shue et al. (1998) model at high latitudes is found to be caused by the solar-wind parameters that are similar to those in the equatorial plane. Finally, we highlight the importance of the dipole tilt angle at high latitudes. Our results may be useful for the interpretation of plasma measurements from the upcoming SMILE mission (Branduardi-Raymont et al., 2018) as this spacecraft will also fly frequently through the high-latitude magnetopause.
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Journal articlePal S, dos Santos LFG, Weiss AJ, et al., 2024,
Automatic Detection of Large-scale Flux Ropes and Their Geoeffectiveness with a Machine-learning Approach
, ASTROPHYSICAL JOURNAL, Vol: 972, ISSN: 0004-637X -
Journal articleBowen TA, Vasko IY, Bale SD, et al., 2024,
Extended Cyclotron Resonant Heating of the Turbulent Solar Wind
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 972, ISSN: 2041-8205 -
Journal articleDavies EE, Ruedisser HT, Amerstorfer UV, et al., 2024,
Flux Rope Modeling of the 2022 September 5 Coronal Mass Ejection Observed by Parker Solar Probe and Solar Orbiter from 0.07 to 0.69 au
, ASTROPHYSICAL JOURNAL, Vol: 973, ISSN: 0004-637X -
Journal articleErvin T, Bale SD, Badman ST, et al., 2024,
Near Subsonic Solar Wind Outflow from an Active Region
, ASTROPHYSICAL JOURNAL, Vol: 972, ISSN: 0004-637X -
Journal articleHuang Z, Shi C, Velli M, et al., 2024,
Solar Wind Structures from the Gaussianity of Magnetic Magnitude
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 973, ISSN: 2041-8205 -
Journal articleRussell J, Bantges R, Brindley H, et al., 2024,
The GERB Obs4MIPs: a dataset for evaluating diurnal and monthly variation in top of atmosphere radiative fluxes in climate models
, Earth System Science Data, Vol: 16, Pages: 4243-4266, ISSN: 1866-3508A newly available radiative flux dataset specifically designed to enable the evaluation of the diurnal cycle in top-of-atmosphere (TOA) fluxes as captured by climate and Earth system models is presented. Observations over the period 2007–2012 made by the Geostationary Earth Radiation Budget (GERB) instrument are used to derive monthly hourly mean outgoing longwave radiation (OLR) and reflected shortwave (RSW) fluxes on a regular 1° latitude–longitude grid covering approximately 60° N–60° S and 60° E–60° W. The impact of missing data is evaluated in detail, and a data-filling solution is implemented using estimates of broadband fluxes from the Spinning Enhanced Visible and Infrared Imager flying on the same Meteosat platform, scaled to the GERB observations. This relatively simple approach is shown to deliver an approximate improvement by a factor of 10 in both the bias caused by missing data and the associated variability in the error. To demonstrate the utility of this V1.1 filled GERB Observations for Climate Model Intercomparison Projects (Obs4MIPs) dataset, comparisons are made to radiative fluxes from two climate configurations of the Hadley Centre's Global Environmental Model: HadGEM3-GC3.1 and HadGEM3-GC5.0. Focusing on marine stratocumulus and deep convective cloud regimes, diurnally resolved comparisons between the models and observations highlight discrepancies between the model configurations in terms of their ability to capture the diurnal amplitude and the phase in TOA fluxes, details that cannot be diagnosed by comparisons at lower temporal resolutions. For these cloud regimes the GC5.0 configuration shows improved fidelity to the observations relative to GC3.1, although notable differences remain. The V1.1 filled GERB Obs4MIPs monthly hourly TOA fluxes are available from the Centre for Environmental Data Analysis, with the OLR fluxes accessible at https://doi.org/10.5285/90148d9b1
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Journal articleRivera YJ, Badman ST, Stevens ML, et al., 2024,
In situ observations of large-amplitude Alfvén waves heating and accelerating the solar wind
, SCIENCE, Vol: 385, Pages: 962-966, ISSN: 0036-8075 -
Journal articleKelly H, Archer M, Ma X, et al., 2024,
Identification of Kelvin-Helmholtz generated vortices in magnetised fluids
, Frontiers in Astronomy and Space Sciences, Vol: 11, ISSN: 2296-987XThe Kelvin-Helmholtz Instability (KHI), arising from velocity shear across the magnetopause, plays a significant role in the viscous-like transfer of mass, momentum, and energy from the shocked solar wind into the magnetosphere. While the KHI leads to growth of surface waves and vortices, suitable detection methods for these applicable to magnetohydrodynamics (MHD) are currently lacking. A novel method is derived based on the well-established λ-family of hydrodynamic vortex identification techniques, which define a vortex as a local minimum in an adapted pressure field. The J × B Lorentz force is incorporated into this method by using an effective total pressure in MHD, including both magnetic pressure and a pressure-like part of the magnetic tension derived from a Helmholtz decomposition. The λMHD method is shown to comprise of four physical effects: vortical momentum, density gradients, fluid compressibility, and the rotational part of the magnetic tension. A local three-dimensional MHD simulation representative of near-flank magnetopause conditions (plasma β’s 0.5–5 and convective Mach numbers Mf ∼ 0.4) under northward interplanetary magnetic field (IMF) is used to validate λMHD. Analysis shows it correlates well with hydrodynamic vortex definitions, though the level of correlation decreases with vortex evolution. Overall, vortical momentum dominates λMHD at all times. During the linear growth phase, density gradients act to oppose vortex formation. By the highly nonlinear stage, the formation of small-scale structures leads to a rising importance of the magnetic tension. Compressibility was found to be insignificant throughout. Finally, a demonstration of this method adapted to tetrahedral spacecraft observations is performed.
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Journal articleCheng S, Chassagnon H, Kasoar M, et al., 2025,
Deep Learning Surrogate Models of JULES-INFERNO for Wildfire Prediction on a Global Scale
, IEEE TRANSACTIONS ON EMERGING TOPICS IN COMPUTATIONAL INTELLIGENCE, ISSN: 2471-285X -
Journal articleWarwick L, Murray JE, Brindley H, 2024,
The Far-INfrarEd Spectrometer for Surface Emissivity (FINESSE) – Part 2: First measurements of the emissivity of water in the far-infrared
, Atmospheric Measurement Techniques, Vol: 17, Pages: 4777-4787<jats:p>Abstract. In this paper, we describe a method for retrieving the surface emissivity of specular surfaces across the wavenumber range of 400–1600 cm−1 using novel radiance measurements of the Far-INfrarEd Spectrometer for Surface Emissivity (FINESSE) instrument. FINESSE is described in detail in Part 1 (Murray et al., 2024) of this paper. We apply the method to two sets of measurements of distilled water. The first set of emissivity retrievals is of distilled water heated above ambient temperature to enhance the signal-to-noise ratio. The second set of emissivity retrievals is of ambient temperate water at a range of viewing angles. In both cases, the observations agree well with calculations based on compiled refractive indices across the mid- and far-infrared. It is found that the reduced contrast between the up- and downwelling radiation in the ambient temperature case degrades the performance of the retrieval. Therefore, a filter is developed to target regions of high contrast, which improves the agreement between the ambient temperature emissivity retrieval and the predicted emissivity. These retrievals are, to the best of our knowledge, the first published simultaneous retrievals of the surface temperature and emissivity of water that extend into the far-infrared and demonstrate a method that can be used and further developed for the in situ retrieval of the emissivity of other surfaces in the field. </jats:p>
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Journal articleGettelman A, Christensen MW, Diamond MS, et al., 2024,
Has reducing ship emissions brought forward global warming?
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276Ships brighten low marine clouds from emissions of sulfur and aerosols, resulting in visible “ship tracks”. In 2020, new shipping regulations mandated an ∼80% reduction in the allowed fuel sulfur content. Recent observations indicate that visible ship tracks have decreased. Model simulations indicate that since 2020 shipping regulations have induced a net radiative forcing of +0.12 Wm−2. Analysis of recent temperature anomalies indicates Northern Hemisphere surface temperature anomalies in 2022–2023 are correlated with observed cloud radiative forcing and the cloud radiative forcing is spatially correlated with the simulated radiative forcing from the 2020 shipping emission changes. Shipping emissions changes could be accelerating global warming. To better constrain these estimates, better access to ship position data and understanding of ship aerosol emissions are needed. Understanding the risks and benefits of emissions reductions and the difficultly in robust attribution highlights the large uncertainty in attributing proposed deliberate climate intervention.
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Journal articleBrunmayr AS, Hagedorn F, Moreno Duborgel M, et al., 2024,
Radiocarbon analysis reveals underestimation of soil organic carbon persistence in new-generation soil models
, GEOSCIENTIFIC MODEL DEVELOPMENT, Vol: 17, Pages: 5961-5985, ISSN: 1991-959X -
Journal articleArcher M, Shi X, Walach M-T, et al., 2024,
Crucial future observations and directions for unveiling magnetopause dynamics and their geospace impacts
, Frontiers in Astronomy and Space Sciences, Vol: 11, ISSN: 2296-987XThe dynamics of Earth's magnetopause, driven by several different external/internal physical processes, plays a major role in the geospace energy budget. Given magnetopause motion couples across many space plasma regions, numerous forms of observations may provide valuable information in understanding these dynamics and their impacts. \textit{In-situ} multi-point spacecraft measurements measure the local plasma environment, dynamics and processes; with upcoming swarms providing the possibility of improved spatiotemporal reconstruction of dynamical phenomena, and multi-mission conjunctions advancing understanding of the mesoscale'' coupling across the geospace system of systems''. Soft X-ray imaging of the magnetopause should enable boundary motion to be directly remote sensed for the first time. Indirect remote sensing capabilities might be enabled through the field-aligned currents associated with disturbances to the magnetopause; by harnessing data from satellite mega-constellations in low-Earth orbit, and taking advantage of upgraded auroral imaging and ionospheric radar technology. Finally, increased numbers of closely-spaced ground magnetometers in both hemispheres may help discriminate between high-latitude processes in what has previously been a zone of confusion''. Bringing together these multiple modes of observations for studying magnetopause dynamics is crucial. These may also be aided by advanced data processing techniques, such as physics-based inversions and machine learning methods, along with comparisons to increasingly sophisticated geospace assimilative models and simulations.
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Journal articleTrotta D, Dimmock AP, Blanco-Cano X, et al., 2024,
Observation of a Fully-formed Forward–Reverse Shock Pair due to the Interaction between Two Coronal Mass Ejections at 0.5 au
, The Astrophysical Journal Letters, Vol: 971, Pages: L35-L35, ISSN: 2041-8205<jats:title>Abstract</jats:title> <jats:p>We report direct observations of a fast magnetosonic forward–reverse shock pair observed by Solar Orbiter on 2022 March 8 at the short heliocentric distance of 0.5 au. The structure, sharing some features with fully-formed stream interaction regions, is due to the interaction between two successive coronal mass ejections (CMEs), never previously observed to give rise to a forward–reverse shock pair. The scenario is supported by remote observations from extreme ultraviolet cameras and coronagraphs, where two candidate eruptions compatible with the in situ signatures have been found. In the interaction region, we find enhanced energetic particle activity, strong nonradial flow deflections, and evidence of magnetic reconnection. At 1 au, well radially aligned Wind observations reveal a complex event, with characteristic observational signatures of both stream interaction region and CME–CME interaction, thus demonstrating the importance of investigating the complex dynamics governing solar eruptive phenomena.</jats:p>
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Journal articlePhan TD, Drake JF, Larson D, et al., 2024,
Multiple Subscale Magnetic Reconnection Embedded inside a Heliospheric Current Sheet Reconnection Exhaust: Evidence for Flux Rope Merging
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 971, ISSN: 2041-8205 -
Journal articleVinogradov A, Alexandrova O, Demoulin P, et al., 2024,
Embedded Coherent Structures from Magnetohydrodynamics to Sub-ion Scales in Turbulent Solar Wind at 0.17 au
, ASTROPHYSICAL JOURNAL, Vol: 971, ISSN: 0004-637X -
Journal articleShi C, Zhao J, Liu S, et al., 2024,
Coexistence of Antisunward and Sunward Ion Cyclotron Waves in the Near-Sun Solar Wind: Excitation by the Proton Cyclotron Instability
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 971, ISSN: 2041-8205 -
Journal articleTosi F, Roatsch T, Galli A, et al., 2024,
Characterization of the Surfaces and Near-Surface Atmospheres of Ganymede, Europa and Callisto by JUICE
, SPACE SCIENCE REVIEWS, Vol: 220, ISSN: 0038-6308 -
Journal articleMurray JE, Warwick L, Brindley H, et al., 2024,
The Far-INfrarEd Spectrometer for Surface Emissivity (FINESSE) – Part 1: instrument description and level 1 radiances
, Atmospheric Measurement Techniques, Vol: 17, Pages: 4757-4775, ISSN: 1867-1381The Far-INfrarEd Spectrometer for Surface Emissivity (FINESSE) instrument combines a commercial Bruker EM27 spectrometer with a front-end viewing and calibration rig developed at Imperial College London. FINESSE is specifically designed to enable accurate measurements of surface emissivity, covering the range 400–1600 cm−1, and, as part of this remit, can obtain views over the full 360° angular range.In this part, Part 1, we describe the system configuration, outlining the instrument spectral characteristics, our data acquisition methodology, and the calibration strategy. As part of the process, we evaluate the stability of the system, including the impact of knowledge of blackbody (BB) target emissivity and temperature. We also establish a numerical description of the instrument line shape (ILS), which shows strong frequency-dependent asymmetry. We demonstrate why it is important to account for these effects by assessing their impact on the overall uncertainty budget on the level 1 radiance products from FINESSE. Initial comparisons of observed spectra with simulations show encouraging performance given the uncertainty budget.
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Journal articleWilliams RG, Meijers AJS, Roussenov VM, et al., 2024,
Asymmetries in the Southern Ocean contribution to global heat and carbon uptake
, Nature Climate Change, Vol: 14, Pages: 823-831, ISSN: 1758-678XThe Southern Ocean provides dominant contributions to global ocean heat and carbon uptake, which is widely interpreted as resulting from its unique upwelling and circulation. Here we show a large asymmetry in these contributions, with the Southern Ocean accounting for 83 ± 33% of global heat uptake versus 43 ± 3% of global ocean carbon uptake over the historical period in state-of-the-art climate models. Using single radiative forcing experiments, we demonstrate that this historical asymmetry is due to suppressed heat uptake by northern oceans from enhanced aerosol forcing. In future projections, such as SSP2-4.5 where greenhouse gases increasingly dominate radiative forcing, the Southern Ocean contributions to global heat and carbon uptake become more comparable, 52 ± 5% and 47 ± 4%, respectively. Hence, the past is not a reliable indicator of the future, with the northern oceans becoming important for heat uptake while the Southern Ocean remains important for both heat and carbon uptake.
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Journal articleWarwick L, Murray J, Brindley H, 2024,
The Far-INfrarEd Spectrometer for Surface Emissivity (FINESSE) Part II: first measurements of the emissivity of water in the far-infrared
, Atmospheric Measurement Techniques, Vol: 17, Pages: 4777-4787, ISSN: 1867-1381In this paper we describe a method for retrieving surface emissivity across the wavenumber range 400–1600 cm-1 using novel radiance measurements from the Far INfrarEd Spectrometer for Surface Emissivity (FINESSE) instrument. FINESSE is described in detail in part I of this paper. We apply the method to two sets of measurements of distilled water. The first set of emissivity retrievals is of distilled water heated above ambient temperature to enhance the signal to noise ratio. The second set of emissivity retrievals is of ambient temperate water at a range of viewing angles. In both cases the observations agree well with calculations based on compiled refractive indices across the mid and far-infrared. It is found that the reduced contrast between the up and downwelling radiation in the ambient temperature case degrades the performance of the retrieval. Therefore a filter is developed to target regions of high contrast which improves the agreement between the ambient temperature emissivity retrieval and the predicted emissivity. These retrievals are, to the best of our knowledge, the first published 10 retrievals of the emissivity of water that extend into the far-infrared and demonstrate a method that can be used for the in-situ retrieval of the emissivity of other surfaces in the field.
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Journal articleJohnson D, Hood AW, Cargill PJ, et al., 2024,
The thermodynamic response of heating at coronal null points
, Monthly Notices of the Royal Astronomical Society, Vol: 532, Pages: 4261-4271, ISSN: 0035-8711Magnetic null points are an important aspect of the magnetic field structure of the solar corona and can be sites of enhanced dissipation. This paper uses analytical and numerical models to investigate the plasma structure around a heated null. It is shown that the temperature profile not only differs significantly from that in a uniform field, but also that the profile depends significantly on the spatial structure of the heating. Field lines close to the separatrices and the null point have higher temperatures than a uniform field for the same heating input. The dependence of the results near the null on both the ratio of perpendicular to parallel conduction, and numerical resolution is also explored. The comparison between analytic and numerical solutions also provides a useful benchmark to compare MHD codes with anisotropic thermal conduction.
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Journal articleGryspeerdt E, Stettler M, Teoh R, et al., 2024,
Operational differences lead to longer lifetimes of satellite detectable contrails from more fuel efficient aircraft
, Environmental Research Letters, Vol: 19, ISSN: 1748-9326Clouds produced by aircraft (known as contrails) contribute over half of the positive radiative forcing from aviation, but the size of this warming effect is highly uncertain. Their radiative effect is highly dependent on the microphysical properties and meteorological background state, varying strongly over the contrail lifecycle. In-situ observations have demonstrated an impact of aircraft and fuel type on contrail properties close to the aircraft, but there are few observational constraints at these longer timescales, despite these having a strong impact in high-resolution and global models. This work provides an observational quantification of these contrail controlling factors, matching air traffic data to satellite observations of contrails to isolate the role of the aircraft type in contrail properties and evolution. Investigating over 64 000 cases, a relationship between aircraft type and contrail formation is observed, with more efficient aircraft forming longer-lived satellite-detectable contrails more frequently, which could lead to a larger climate impact. This increase in contrail formation and lifetime is primarily driven by an increase in flight altitude. Business jets are also found to produce longer-lived satellite-detectable contrails despite their lower fuel flow, as they fly at higher altitudes. The increase in satellite-detected contrails behind more efficient aircraft suggests a trade-off between aircraft greenhouse gas emissions and the aviation climate impact through contrail production, due to differences in aircraft operation.
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Journal articleStier P, van den Heever SC, Christensen MW, et al., 2024,
Multifaceted aerosol effects on precipitation
, Nature Geoscience, Vol: 17, Pages: 719-732, ISSN: 1752-0894Aerosols have been proposed to influence precipitation rates and spatial patterns from scales of individual clouds to the globe. However, large uncertainty remains regarding the underlying mechanisms and importance of multiple effects across spatial and temporal scales. Here we review the evidence and scientific consensus behind these effects, categorized into radiative effects via modification of radiative fluxes and the energy balance, and microphysical effects via modification of cloud droplets and ice crystals. Broad consensus and strong theoretical evidence exist that aerosol radiative effects (aerosol–radiation interactions and aerosol–cloud interactions) act as drivers of precipitation changes because global mean precipitation is constrained by energetics and surface evaporation. Likewise, aerosol radiative effects cause well-documented shifts of large-scale precipitation patterns, such as the intertropical convergence zone. The extent of aerosol effects on precipitation at smaller scales is less clear. Although there is broad consensus and strong evidence that aerosol perturbations microphysically increase cloud droplet numbers and decrease droplet sizes, thereby slowing precipitation droplet formation, the overall aerosol effect on precipitation across scales remains highly uncertain. Global cloud-resolving models provide opportunities to investigate mechanisms that are currently not well represented in global climate models and to robustly connect local effects with larger scales. This will increase our confidence in predicted impacts of climate change.
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Journal articleWang S, Ren T, Yang P, et al., 2024,
Improved temperature-dependent ice refractive index compilation in the far-infrared spectrum
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276A new ice refractive index compilation is reported for a broad spectrum ranging from 0.0443 to 106 𝜇m, focusing on the pronounced temperature-dependence of ice optical properties in the far-infrared (far-IR) segment (15-100 µm). A sensitivity study assuming spherical particles shows that selecting ice refractive indices at 12 temperatures and 215 wavelengths in the far-IR region gives sufficient accuracy in interpolated refractive indices for developing a new ice crystal optical property database. Furthermore, we demonstrate the differences between the bulk single-scattering properties computed for hexagonal ice particles with this new compilation compared to a previous iteration at three far-IR wavelengths where substantial differences are noticed between the two ice refractive index compilations. We suggest that our new ice refractive index dataset will improve downstream light-scattering applications for upcoming far-IR satellite missions and allow robust modeling of outgoing longwave radiation (OLR) under ice cloud conditions.
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Journal articleChen L-J, Gershman D, Burkholder B, et al., 2024,
Earth's Alfvén Wings Driven by the April 2023 Coronal Mass Ejection
, GEOPHYSICAL RESEARCH LETTERS, Vol: 51, ISSN: 0094-8276 -
Journal articleSouthwood D, 2024,
Go/no-go for a Mars samples return
, SCIENCE, Vol: 385, Pages: 233-233, ISSN: 0036-8075 -
Journal articleGreene SM, Schachat SR, Arita-Merino N, et al., 2024,
Accessible interview practices for disabled scientists and engineers
, ISCIENCE, Vol: 27
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