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Journal articleCeppi P, Myers TA, Nowack P, et al., 2024,
Implications of a Pervasive Climate Model Bias for Low-Cloud Feedback
, GEOPHYSICAL RESEARCH LETTERS, Vol: 51, ISSN: 0094-8276 -
Journal articleAuestad H, Spensberger C, Marcheggiani A, et al., 2024,
Spatio-temporal averaging of jets obscures the reinforcement of baroclinicity by latent heating
, WEATHER AND CLIMATE DYNAMICS, Vol: 5, Pages: 1269-1286 -
Journal articleMozer FS, Agapitov O, Bale SD, et al., 2024,
Origin of the type III radiation observed near the Sun
, ASTRONOMY & ASTROPHYSICS, Vol: 690, ISSN: 0004-6361 -
Journal articleRivera YJ, Badman ST, Stevens ML, et al., 2024,
Mixed Source Region Signatures inside Magnetic Switchback Patches Inferred by Heavy Ion Diagnostics
, ASTROPHYSICAL JOURNAL, Vol: 974, ISSN: 0004-637X -
Journal articleCastrillejo M, Hansman RL, Graven HD, et al., 2024,
Comparability of radiocarbon measurements in dissolved inorganic carbon of seawater produced at ETH-Zurich
, Radiocarbon: an international journal of cosmogenic isotope research, Vol: 66, Pages: 1054-1063, ISSN: 0033-8222Radiocarbon observations (Δ14C) in dissolved inorganic carbon (DIC) of seawater provide useful information about ocean carbon cycling and ocean circulation. To deliver high-quality observations, the Laboratory of Ion Beam Physics (LIP) at ETH-Zurich developed a new simplified method allowing the rapid analysis of radiocarbon in DIC of small seawater samples, which is continually assessed by following internal quality controls. However, a comparison with externally produced 14C measurements to better establish an equivalency between methods was still missing. Here, we make the first intercomparison with the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility based on 14 duplicate seawater samples collected in 2020. We also compare with prior deep-water observations from the 1970s to 1990s. The results show a very good agreement in both comparisons. The mean Δ14C of 12 duplicate samples measured by LIP and NOSAMS were statistically identical within one sigma uncertainty while two other duplicate samples agreed within two sigma. Based on this small number of duplicate samples, LIP values appear to be slightly lower than the NOSAMS values, but more measurements will be needed for confirmation. We also comment on storage and preservation techniques used in this study, including the freezing of samples collected in foil bags.
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Journal articleLee D, Sparrow S, Leach N, et al., 2024,
The Attribution of February Extremes over North America: A Forecast-Based Storyline Study
, Journal of Climate, Vol: 37, Pages: 5073-5089, ISSN: 0894-8755The importance of extreme event attribution rises as climate change causes severe damage to populations resulting from unprecedented events. In February 2019, a planetary wave shifted along the U.S.–Canadian border, simultaneously leading to troughing with anomalous cold events and ridging over Alaska and northern Canada with abnormal warm events. Also, a dry-stabilized anticyclonic circulation over low latitudes induced warm extreme events over Mexico and Florida. Most attribution studies compare the climate model simulations under natural or actual forcing conditions and assess probabilistically from a climatological point of view. However, in this study, we use multiple ensembles from an operational forecast model, promising statistical as well as dynamically constrained attribution assessment, often referred to as the storyline approach to extreme event attribution. In the globally averaged results, increasing CO2 concentrations lead to distinct warming signals at the surface, resulting mainly from diabatic heating. Our study finds that CO2-induced warming eventually affects the possibility of extreme events in North America, quantifying the impact of anthropogenic forcing over less than a week’s forecast simulation. Our study assesses the validity of the storyline approach conditional on the forecast lead times, which is hindered by rising noise in CO2 signals and the declining performance of the forecast model. The forecast-based storyline approach is valid for at least half of the land area within a 6-day lead time before the target extreme occurrence. Our attribution results highlight the importance of achieving net-zero emissions ahead of schedule to reduce the occurrence of severe heatwaves.
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Journal articleCuesta ME, Cummings AT, Livadiotis G, et al., 2024,
Observations of Kappa Distributions in Solar Energetic Protons and Derived Thermodynamic Properties
, ASTROPHYSICAL JOURNAL, Vol: 973, ISSN: 0004-637X -
Journal articleMurray-Watson R, Gryspeerdt E, 2024,
Air mass history linked to the development of Arctic mixed-phase clouds
, Atmospheric Chemistry and Physics, Vol: 24, Pages: 11115-11132, ISSN: 1680-7316Clouds formed during marine cold-air outbreaks (MCAOs) exhibit a distinct transition from stratocumulus decks near the ice edge to broken cumuliform fields further downwind. The mechanisms associated with ice formation are believed to be crucial in driving this transition, yet the factors influencing such formation remain unclear. Through Lagrangian trajectories collocated with satellite data, this study investigates the development of mixed-phase clouds using these outbreaks. Cloud formed in MCAOs are characterized by a swift shift from liquid to ice-containing states, contrasting with non-MCAO clouds also moving off the ice edge. These mixed-phase clouds are predominantly observed at temperatures below −20 °C near the ice edge. However, further into the outbreak, they become dominant at temperatures as high as −13 °C. This shift is consistent with the influence of biological ice-nucleating particles (INPs), which become more prevalent as the air mass ages over the ocean. The evolution of these clouds is closely linked to the history of the air mass, especially the length of time it spends over snow- and ice-covered surfaces – terrains may that be deficient in INPs. This connection also accounts for the observed seasonal variations in the development of Arctic clouds, both within and outside of MCAO events. The findings highlight the importance of understanding both local marine aerosol sources near the ice edge and the overarching INP distribution in the Arctic for modelling of cloud phase in the region.
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Journal articleQuaas J, Andrews T, Bellouin N, et al., 2024,
Adjustments to climate perturbations—mechanisms, implications, observational constraints
, AGU Advances, Vol: 5, ISSN: 2576-604XSince the 5th Assessment Report of the Intergovernmental Panel on Climate Change (AR5) an extended concept of the energetic analysis of climate change including forcings, feedbacks and adjustment processes has become widely adopted. Adjustments are defined as processes that occur in response to the introduction of a climate forcing agent, but that are independent of global-mean surface temperature changes. Most considered are the adjustments that impact the Earth energy budget and strengthen or weaken the instantaneous radiative forcing due to the forcing agent. Some adjustment mechanisms also impact other aspects of climate not related to the Earth radiation budget. Since AR5 and a following description by Sherwood et al. (2015, https://doi.org/10.1175/bams-d-13-00167.1), much research on adjustments has been performed and is reviewed here. We classify the adjustment mechanisms into six main categories, and discuss methods of quantifying these adjustments in terms of their potentials, shortcomings and practicality. We furthermore describe aspects of adjustments that act beyond the energetic framework, and we propose new ideas to observe adjustments or to make use of observations to constrain their representation in models. Altogether, the problem of adjustments is now on a robust scientific footing, and better quantification and observational constraint is possible. This allows for improvements in understanding and quantifying climate change.
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Journal articleWaters C, Eastwood J, Fargette N, et al., 2024,
Classifying magnetic reconnection regions using k-means clustering: applications to energy partition
, JGR: Space Physics, Vol: 129, ISSN: 2169-9402Magnetic reconnection is a fundamental plasma process which facilitates the conversion of magnetic energy to particle energies. This local process both contributes to and is affected by a larger system, being dependent on plasma conditions and transporting energy around the system, such as Earth's magnetosphere. When studying the reconnection process with in situ spacecraft data, it can be difficult to determine where spacecraft are in relation to the reconnection structure. In this work, we use k-means clustering, an unsupervised machine learning technique, to identify regions in a 2.5-D PIC simulation of symmetric magnetic reconnection with conditions comparable to those observed in Earth’s magnetotail. This allows energy flux densities to be attributed to these regions. The ion enthalpy flux density is the most dominant form of energy flux density in the outflows, agreeing with previous studies. Poynting flux density may be dominant at some points in the outflows and is only half that of the Poynting flux density in the separatrices. The proportion of outflowing particle energy flux decreases as guide field increases. We find that k-means is beneficial for analysing data and comparing between simulations and in situ data. This demonstrates an approach which may be applied to large volumes of data to determine statistically different regions within phenomena in simulations and could be extended to in situ observations, applicable to future multi-point missions.
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Journal articleFargette N, Eastwood JP, Waters CL, et al., 2024,
Statistical study of energy transport and conversion in electron diffusion regions at earth's dayside magnetopause
, Journal of Geophysical Research: Space Physics, Vol: 129, ISSN: 2169-9380The electron diffusion region (EDR) is a key region for magnetic reconnection, but the typical energy transport and conversion in EDRs is still not well understood. In this work, we perform a statistical study of 80 previously published near X-line events identified at the dayside magnetopause in Magnetospheric Multiscale data. We find 44 events that clearly present all commonly accepted EDR signatures and use this database to investigate energy flux partition and energy conversion. We find that energy partition is changed inside EDRs, with a 71%–29% allocation of particle energy flux density between electrons and ions respectively. The electron enthalpy flux density is found to dominate locally at all EDRs and is predominantly oriented in the out-of-plane direction, perpendicular to the reconnecting magnetic field. We also examine the transition from electron- to ion-dominated energy flux partition further from the EDR, finding this typically occurs at scales of the order of the ion inertial length, larger than the typical EDR size. We then investigate energy conversion and transport and highlight complex processes, with potential non-steady-state energy accumulation and release near the EDR. We discuss the implications of our results for reconnection energy conversion, and for magnetopause dynamics in general.
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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 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 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 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 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 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 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 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 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 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 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
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