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Journal articleNykyri K, Di Matteo S, Archer MO, et al., 2024,
Could a low‐frequency perturbation in the Earth's magnetotail be generated by the lunar wake?
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276Both ground based magnetometers and ionospheric radars at Earth have frequently detected Ultra Low Frequency (ULF) fluctuations at discrete frequencies extending below one mHz-range. Many dayside solar wind drivers have been convincingly demonstrated as driver mechanisms. In this paper we investigate and propose an additional, nightside generation mechanism of a low frequency magnetic field fluctuation. We propose that the Moon may excite a magnetic field perturbation of the order of 1 nT at discrete frequencies when it travels through the Earth's magnetotail 4–5 days every month. Our theoretical prediction is supported by a case study of ARTEMIS magnetic field measurements at the lunar orbit in the Earth's magnetotail. ARTEMIS detects statistically significant peaks in magnetic field fluctuation power at frequencies of 0.37–0.47 mHz that are not present in the solar wind.
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Journal articleZeng Z, Yao Z, Liu J, et al., 2024,
Ultralow-frequency waves in Jupiter’s magnetopause boundary layer
, The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 976, ISSN: 0004-637XUltralow-frequency (ULF) waves (∼tens of minutes period) are widely identified in the Jovian system and are believed to be associated with energy dissipation in the magnetosphere and ionosphere. Due to the magnetodisk oscillation related to planetary rotation, it is challenging to identify the periodicities inside the magnetosphere, although remote sensing observations of the polar emissions provide clear evidence of the tens of minutes pulsations. In this study, we take advantage of Juno's in situ measurements in the magnetopause boundary layer for a long duration, i.e., >4 hr, to directly assess the tens of minutes periodicities of the boundary dynamics caused by the interactions between the internal plasma and external solar wind. Through periodogram analysis on the magnetic field and particle data, we find ULF waves with periodicities of ∼18 minutes, ∼40 minutes, and ∼70–80 minutes, which is generally consistent with pulsations in multiple remote sensing observations. A multiple-harmonic ULF phenomenon was also identified in the observations. The periodicities from in situ measurements provide crucial clues in understanding the origin of pulsating wave/auroral emissions in the Jovian system. The results could also further our understanding of energy transfer and release between the internal plasma of Jupiter and external solar wind.
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Journal articleOpie S, Verscharen D, Chen CHK, et al., 2024,
Temperature anisotropy instabilities driven by intermittent velocity shears in the solar wind
, JOURNAL OF PLASMA PHYSICS, Vol: 90, ISSN: 0022-3778 -
Journal articleEllmeier M, Betzler A, Amtmann C, et al., 2024,
Lower magnetic field measurement limit of the coupled dark state magnetometer
, MEASUREMENT SCIENCE AND TECHNOLOGY, Vol: 35, ISSN: 0957-0233 -
Journal articleLario D, Balmaceda LA, Gomez-Herrero R, et al., 2024,
A Rapid Sequence of Solar Energetic Particle Events Associated with a Series of Extreme-ultraviolet Jets: Solar Orbiter, STEREO-A, and Near-Earth Spacecraft Observations
, ASTROPHYSICAL JOURNAL, Vol: 975, ISSN: 0004-637X -
Journal articleJebaraj IC, Agapitov OV, Gedalin M, et al., 2024,
Direct Measurements of Synchrotron-emitting Electrons at Near-Sun Shocks
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 976, ISSN: 2041-8205 -
Journal articleChen L, Ma B, Wu D, et al., 2024,
Spectral Characteristics of Fundamental-Harmonic Pairs of Interplanetary Type III Radio Bursts Observed by PSP
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 975, ISSN: 2041-8205 -
Journal articleErvin T, Jaffarove K, Badman ST, et al., 2024,
Characteristics and Source Regions of Slow Alfvénic Solar Wind Observed by Parker Solar Probe
, ASTROPHYSICAL JOURNAL, Vol: 975, ISSN: 0004-637X -
Journal articleBlyth L, Graven H, Manning AJ, et al., 2024,
Radiocarbon as a tracer of the fossil fraction of regional carbon monoxide emissions
, ENVIRONMENTAL RESEARCH LETTERS, Vol: 19, ISSN: 1748-9326 -
Journal articleMasters A, 2024,
Solar wind power likely governs Uranus’ thermosphere temperature
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276Observations of Uranus in the near-infrared by ground-based telescopes from 1992 to 2018 have shown that the planet's upper atmosphere (thermosphere) steadily cooled from ∼700 to ∼450 K. We explain this cooling as due to the concurrent decline in the power of the solar wind incident on Uranus' magnetic field, which has dropped by ∼50% over the same period due to solar activity trends longer than the 11-year solar cycle. Uranus' thermosphere appears to be more strongly governed by the solar wind than any other planet where we have assessed this coupling so far. Uranus' total auroral power may also have declined, in contrast with the power of the radio aurora that we expect has been predominantly modulated by the solar cycle. In the absence of strong local driving, planets with sufficiently large magnetospheres may also have thermospheres predominantly governed by the stellar wind, rather than stellar radiation.
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ReportOtto F, Clarke B, Barnes C, et al., 2024,
10 years of rapidly disentangling drivers of extreme weather disasters
, Publisher: Centre for Environmental Policy -
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: 0094-8276How low clouds respond to warming constitutes a key uncertainty for climate projections. Herewe observationally constrain low‐cloud feedback through a controlling factor analysis based on ridgeregression. We find a moderately positive global low‐cloud feedback (0.45 W m− 2 K− 1, 90% range 0.18–0.72 Wm− 2 K− 1), about twice the mean value (0.22 W m− 2 K− 1) of 16 models from the Coupled ModelIntercomparison Project. We link this discrepancy to a pervasive model mean‐state bias: models underestimatethe low‐cloud response to warming because (a) they systematically underestimate present‐day tropical marinelow‐cloud amount, and (b) the low‐cloud sensitivity to warming is proportional to this present‐day low‐cloudamount. Our results hence highlight the importance of reducing model biases in both the mean state of cloudsand their sensitivity to environmental factors for accurate climate change projections
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Journal articleChakravorty S, Czaja A, Parfitt R, et al., 2024,
Tropospheric response to gulf stream intrinsic variability: a model ensemble approach
, Geophysical Research Letters, Vol: 51, ISSN: 0094-8276The Gulf Stream's (GS) impact on the marine boundary layer (MBL) is well established, yet the mechanisms and timescales through which it affects the upper-troposphere and contributes to precipitation are debatable. Using a high-resolution regional atmospheric model, we shed light on the impact of ocean intrinsic variability (OIV) along GS on midlatitude-atmosphere. Taking advantage of a 24-member ensemble of ocean model integrations, we devised a novel experimental setup where the same weather system feels different realizations of GS sea surface temperature (SST). We introduce the “Eddy Recharge-Frontal Lift” (ERFL) mechanism, highlighting the joint importance of synoptic variability and boundary layer processes. ERFL mechanism proposes that OIV recharges/discharges MBL with moisture and heat, while convergence associated with passing atmospheric-fronts uplifts these MBL-trapped anomalies to upper-troposphere and imprints on precipitation in surprisingly short periods (a month). The impact of OIV on precipitation depends on the background mean SST.
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Journal articleTannous SM, Bonnell JW, Pulupa M, et al., 2024,
Electron Temperatures in the Venusian Ionosphere From Parker Solar Probe Using Quasi-Thermal Noise Spectroscopy
, 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, ISSN: 2698-4016Latent heating modifies the jet stream by modifying the vertical geostrophic wind shear, thereby altering the potential for baroclinic development. Hence, correctly representing diabatic effects is important for modelling the mid-latitude atmospheric circulation and variability. However, the direct effects of diabatic heating remain poorly understood. For example, there is no consensus on the effect of latent heating on the cross-jet temperature contrast. We show that this disagreement is attributable to the choice of spatio-temporal averaging. Jet representations relying on averaged wind tend to have the strongest latent heating on the cold flank of the jet, thus weakening the cross-jet temperature contrast. In contrast, jet representations reflecting the two-dimensional instantaneous wind field have the strongest latent heating on the warm flank of the jet. Furthermore, we show that latent heating primarily occurs on the warm flank of poleward directed instantaneous jets, which is the case for all storm tracks and seasons.
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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 -
ReportClarke B, Barnes C, Sparks N, et al., 2024,
Climate change key driver of catastrophic impacts of Hurricane Helene that devastated both coastal and inland communities
, Publisher: Centre for Environmental Policy -
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 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 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 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 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 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: 0894-8755- Cite
- Citations: 1
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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 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
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