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Journal articleLai T, Toumi R, 2025, , Quarterly Journal of the Royal Meteorological Society, Vol: 151, ISSN: 0035-9009
It is projected that the sea surface temperature (SST) increases under climate change and enhances tropical cyclone (TC) intensification directly. An opposing expected feature of climate change is the strengthening atmospheric static stability, which may suppress intensification. The intensity and diabatic heating are closely related through the secondary circulation, but it has been unclear whether both will change at the same rate. Here we show that they respond differently to stability changes. The efficiency of converting diabatic heating to kinetic energy (KE) of TCs to SST and static stability during the intensification stage is examined. In a set of idealised simulations, the efficiency does not have a significant relation with the SST. However the efficiency is found to decrease with increasing static stability at a rate of about -5 % ⋅K‾¹. It is shown that the KE increment declines, while the diabatic heating in the eyewall remains unchanged with larger static stability. The decrease in KE gain at the eyewall is associated with an enhanced outward advection of absolute angular momentum. The combined effect of enhanced water鈥恦apour supply and the slightly reduced updraft at the eyewall keeps the diabatic heating steady with varying static stability. This study demonstrates the complex effects of enhanced static stability, which is expected to accompany surface warming, on tropical cyclones.
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Journal articleMauel M, Bale SD, Fox NJ, et al., 2025, , PHYSICS OF PLASMAS, Vol: 32, ISSN: 1070-664X
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- Citations: 1
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Book chapterGalli A, Vorburger A, Wurz P, et al., 2025, , Ganymede, Editors: Volwerk, McGrath, Jia, Spohn, Publisher: Cambridge University Press, Pages: 237-251, ISBN: 9781108966474
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Book chapterGaland M, Carnielli G, Jia X, 2025, , Ganymede, Editors: Volwerk, McGrath, Jia, Spohn, Publisher: Cambridge University Press, Pages: 269-289, ISBN: 9781108966474
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Journal articleAcevski M, Masters A, 2024, , Geophysical Research Letters, Vol: 51, ISSN: 0094-8276
Uranus remains one of the most unexplored planets in our solar system, featuring a distinctive magnetic field structure first observed by NASA's Voyager 2 mission almost 40 years ago. Uranus is particularly notable for its pronounced magnetic field asymmetry, a characteristic unique to the icy giants. Here we show that, in the region where Voyager 2 did not pass (< 4 Ru), the asymmetric magnetic field can distort the trajectories of high energy protons within Uranus' radiation belts such that the particles hit the planet when they otherwise would not have (in a traditional dipole field). This implies that radiation belt protons which start with pitch angles well outside their respective loss cones can drift into a region where the loss cone is much bigger and then precipitate. This occurs preferentially in the magnetic north pole due to its significantly weaker surface field strength.
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Journal articleLewis HC, Stawarz JE, Matteini L, et al., 2024, , Geophysical Research Letters, Vol: 51, ISSN: 0094-8276
Plasma in Earth's magnetosheath rarely experiences interparticle collisions, so kinetic microinstabilities are thought to contribute to regulating the plasma thermodynamics. Instabilities excite waves and redistribute free energy in velocity space, reducing free energy in the velocity distribution function (VDF). Using 24 hr of data spread over 163 intervals of in situ magnetosheath observations by Magnetospheric Multiscale (MMS), we investigate signatures of energy conversion where the turbulent dynamics have locally distorted the VDFs into non-Maxwellian shapes, in the context of electron and ion temperature anisotropy driven instabilities. We find enhanced average energy conversion into the particles along instability boundaries, suggesting turbulence plays a role in redistributing free energy. In so doing, we quantify the energetics associated with unstable conditions for both species. This work provides insight into the open question of how specific plasma processes couple into the turbulent dynamics, ultimately leading to energy dissipation and particle energization in collisionless plasmas.
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Journal articleHarrison JA, Pearce PM, Yang F, et al., 2024, , iScience, Vol: 27, ISSN: 2589-0042
A thermoradiative diode is a device that can generate power through thermal emission from the warm Earth to the cold night sky. Accurate assessment of the potential power output requires knowledge of the downwelling radiation from the atmosphere. Here, accurate modelling of this radiation is used alongside a detailed balance model of a diode at the Earth’s surface temperature to evaluate its performance under nine different atmospheric conditions. In the radiative limit, these conditions yield power densities between 0.34 and 6.5 W.m-2, with optimal bandgaps near 0.094 eV. Restricting the angles of emission and absorption to less than a full hemisphere can marginally increase the power output. Accounting for non-radiative processes, we suggest that if a 0.094 eV device would have radiative efficiencies more than two orders of magnitude lower than a diode with a bandgap near 0.25 eV, the higher bandgap material is preferred.
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Journal articleSilvy Y, Fr枚licher TL, Terhaar J, et al., 2024, , Earth System Dynamics, Vol: 15, Pages: 1591-1628, ISSN: 2190-4979
While international climate policies now focus on limiting global warming to well below 2 °C or pursuing a 1.5 °C level of global warming, the climate modelling community has not provided an experimental design in which all Earth system models (ESMs) converge and stabilize at the same prescribed global warming levels. This gap hampers accurate estimations based on comprehensive ESMs of the carbon emission pathways and budgets needed to meet such agreed warming levels and of the associated climate impacts under temperature stabilization. Here, we apply the Adaptive Emission Reduction Approach (AERA) with ESMs to provide such simulations in which all models converge at 1.5 and 2.0 °C warming levels by adjusting their emissions over time. These emission-driven simulations provide a wide range of emission pathways and resulting atmospheric CO2 projections for a given warming level, uncovering uncertainty ranges that were previously missing in the traditional Coupled Model Intercomparison Project (CMIP) scenarios with prescribed greenhouse gas concentration pathways. Meeting the 1.5 °C warming level requires a 40 % (full model range: 7 % to 76 %) reduction in multi-model mean CO2-forcing-equivalent (CO2-fe) emissions from 2025 to 2030, a 98 % (57 % to 127 %) reduction from 2025 to 2050, and a stabilization at 1.0 (-1.7 to 2.9) PgC yr-1 from 2100 onward after the 1.5 °C global warming level is reached. Meeting the 2.0 °C warming level requires a 47 % (8 % to 92 %) reduction in multi-model mean CO2-fe emissions until 2050 and a stabilization at 1.7 (-1.5 to 2.7) PgC yr-1 from 2100 onward. The on-average positive emissions under stabilized global temperatures are the result of a decreasing transient climate response to cumulative CO2-fe emissions over time under stabilized global warming. This evolution is consistent with a slightly negative zero emissions commitment - initially assumed to be zero - and leads to an increase in the post-2025 CO2-fe em
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ReportMerz N, Clarke B, Basconcillo J, et al., 2024, , Publisher: Centre for Environmental Policy
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Journal articleHuang Z, Velli M, Shi C, et al., 2024, , ASTROPHYSICAL JOURNAL LETTERS, Vol: 977, ISSN: 2041-8205
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Journal articleDing M, Kozuki H, Concepcion F, et al., 2024, , MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 536, Pages: 274-279, ISSN: 0035-8711
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Journal articleTippett A, Gryspeerdt E, Manshausen P, et al., 2024, , Atmospheric Chemistry and Physics, Vol: 24, Pages: 13269-13283, ISSN: 1680-7316
The assessment of aerosol–cloud interactions remains a major source of uncertainty in understanding climate change, partly due to the difficulty in making accurate observations of aerosol impacts on clouds. Ships can release large numbers of aerosols that serve as cloud condensation nuclei, which can create artificially brightened clouds known as ship tracks. These aerosol emissions offer a “natural”, or “opportunistic”, experiment to explore aerosol effects on clouds, while also disentangling meteorological influences. Utilizing ship positions and reanalysis wind fields, we predict ship track locations, colocating them with satellite data to depict the temporal evolution of cloud properties after an aerosol perturbation. Repeating our analysis for a null experiment does not necessarily recover zero signal as expected; instead, it reveals subtleties between different null-experiment methodologies. This study uncovers a systematic bias in prior ship track research, due to the assumption that background gradients will, on average, be linear. We correct for this bias, which is linked to the correlation between wind fields and cloud properties, to reveal the true ship track response.We find that, once this bias is corrected for, the liquid water path (LWP) response after an aerosol perturbation is weak on average. This has important implications for estimates of radiative forcings due to LWP adjustments, as previous responses in unstable cases were overestimated. A noticeable LWP response is only recovered in specific cases, such as marine stratocumulus clouds, where a positive LWP response is found in precipitating or clean clouds. This work highlights subtleties in the analysis of isolated opportunistic experiments, reconciling differences in the LWP response to aerosols reported in previous studies.
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Book chapterBeth A, Galand M, Simon Wedlund C, et al., 2022, , Comets III, Editors: Meech, Combi, Bockelée-Morvan, Raymond, Zolensky, Publisher: University of Arizona Press, ISBN: 9780816553648
This chapter aims at providing the tools and knowledge to understand and model the plasma environment surrounding comets in the innermost part near the nucleus. In particular, our goal is to give an updated post-Rosetta view of this ionised environment: what we knew, what we confirmed, what we overturned, and what we still do not understand.
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Journal articleRovithakis A, Voulgarakis A, 2024, , Atmospheric Science Letters, Vol: 25, ISSN: 1530-261X
Wildfires are significant contributors to atmospheric gases and aerosols, impacting air quality and composition. This pollution from fires also affects radiative forcing, influencing short-term weather patterns and climate dynamics. Our research employs the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to investigate the repercussions of wildfires on aerosol abundances and associated immediate weather responses. We examine the summer season of 2021, a period marked by severe wildfire events in the country during a heatwave period. We conducted sensitivity experiments including and excluding wildfire emissions to measure their effects on aerosol optical depth (AOD), radiative forcing, and weather features such as temperature, humidity, clouds, and atmospheric circulation. Our findings demonstrate that the radiative impacts of wildfires negatively influence the local temperature over the fire smoke plume-affected areas. Conversely, neighbouring areas of continental Greece experience increases in temperature due to remote effects of wildfire emissions, caused by meteorological feedbacks that reduce atmospheric humidity. Crucially, including fire emissions significantly improves the simulated surface temperatures predicted by the model over the Greek domain. Our work demonstrates that wildfire-generated aerosols can significantly impact weather conditions and highlights the importance of including both local radiative effects and remote feedback for achieving more accurate weather prediction.
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Journal articleDing M, Ryabtsev AN, Kononov EY, et al., 2024, , ASTRONOMY & ASTROPHYSICS, Vol: 692, ISSN: 0004-6361
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Journal articleNykyri K, Di Matteo S, Archer MO, et al., 2024, , Geophysical Research Letters, Vol: 51, ISSN: 0094-8276
Both 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, , The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 976, ISSN: 0004-637X
Ultralow-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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Conference paperHarrison J, Pearce P, Yang F, et al., 2024, , 52nd Photovoltaic Specialist Conference, Publisher: IEEE, Pages: 1366-1369, ISSN: 0160-8371
A thermoradiative diode is a device capable of generating power through the emission of infrared light; this allows a diode on Earth to generate power at night through the passive radiative cooling of the Earth. Accurate assessment of the potential power output of such terrestrial thermoradiative diodes requires knowledge of the downwelling radiation incident on the device from the atmosphere. Here, atmospheric modelling of this radiation is used alongside a detailed balance model of the diode to evaluate its performance under nine different atmospheric conditions. In the radiative limit, the sampled conditions yield peak power densities between 0.34 and 6.5 W.m−2, with optimal bandgaps at or near 0.094 eV(13.2 μm). Non-radiative processes are also accounted for, which provides more realistic power density estimates and highlights the threshold past which higher bandgap materials with reduced non-radiative processes should be prioritized over the theoretically ideal low bandgap.
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Journal articleOpie S, Verscharen D, Chen CHK, et al., 2024, , JOURNAL OF PLASMA PHYSICS, Vol: 90, ISSN: 0022-3778
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Journal articleBlyth L, Graven H, Manning AJ, et al., 2024, , ENVIRONMENTAL RESEARCH LETTERS, Vol: 19, ISSN: 1748-9326
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Journal articleLario D, Balmaceda LA, Gomez-Herrero R, et al., 2024, , ASTROPHYSICAL JOURNAL, Vol: 975, ISSN: 0004-637X
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Journal articleJebaraj IC, Agapitov OV, Gedalin M, et al., 2024, , ASTROPHYSICAL JOURNAL LETTERS, Vol: 976, ISSN: 2041-8205
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Journal articleEllmeier M, Betzler A, Amtmann C, et al., 2024, , MEASUREMENT SCIENCE AND TECHNOLOGY, Vol: 35, ISSN: 0957-0233
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Journal articleChen L, Ma B, Wu D, et al., 2024, , ASTROPHYSICAL JOURNAL LETTERS, Vol: 975, ISSN: 2041-8205
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Journal articleErvin T, Jaffarove K, Badman ST, et al., 2024, , ASTROPHYSICAL JOURNAL, Vol: 975, ISSN: 0004-637X
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Journal articleMasters A, 2024, , Geophysical Research Letters, Vol: 51, ISSN: 0094-8276
Observations 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 articleChakravorty S, Czaja A, Parfitt R, et al., 2024, , Geophysical Research Letters, Vol: 51, ISSN: 0094-8276
The 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, , GEOPHYSICAL RESEARCH LETTERS, Vol: 51, ISSN: 0094-8276
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Journal articleCeppi P, Myers TA, Nowack P, et al., 2024, , Geophysical Research Letters, Vol: 51, ISSN: 0094-8276
How low clouds respond to warming constitutes a key uncertainty for climate projections. Herewe observationally constrain low鈥恈loud feedback through a controlling factor analysis based on ridgeregression. We find a moderately positive global low鈥恈loud 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鈥恠tate bias: models underestimatethe low鈥恈loud response to warming because (a) they systematically underestimate present鈥恉ay tropical marinelow鈥恈loud amount, and (b) the low鈥恈loud sensitivity to warming is proportional to this present鈥恉ay low鈥恈loudamount. 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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