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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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Journal articleOpie S, Verscharen D, Chen CHK, et al., 2024, , Journal of Plasma Physics, Vol: 90, ISSN: 0022-3778
Where and under what conditions the transfer of energy between electromagnetic fields and particles takes place in the solar wind remains an open question. We investigate the conditions that promote the growth of kinetic instabilities predicted by linear theory to infer how turbulence and temperature-anisotropy-driven instabilities are interrelated. Using a large dataset from Solar Orbiter, we introduce the radial rate of strain, a novel measure computed from single-spacecraft data, which we interpret as a proxy for the double-adiabatic strain rate. The solar wind exhibits high absolute values of the radial rate of strain at locations with large temperature anisotropy. We measure the kurtosis and skewness of the radial rate of strain from the statistical moments to show that it is non-Gaussian for unstable intervals and increasingly intermittent at smaller scales with a power-law scaling. We conclude that the velocity field fluctuations in the solar wind contribute to the presence of temperature anisotropy sufficient to create potentially unstable conditions.
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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 articleZhang K, Artemyev AV, Li X, et al., 2024, , Journal of Geophysical Research Space Physics, Vol: 129, ISSN: 2169-9380
The rapidly expanding fleet of low-altitude CubeSats equipped with energetic particle detectors brings new opportunities for monitoring the dynamics of the radiation belt and near-Earth plasma sheet. Despite their small sizes, CubeSats can carry state-of-the-art instruments that provide electron flux measurements with finer energy resolution and broader energy coverage, compared to conventional missions such as POES satellites. The recently launched CIRBE CubeSat measures 250–6,000 keV electrons with extremely high energy resolution, however, CIRBE typically only measures locally-trapped electrons and cannot directly measure the precipitating electrons. This work aims to develop a technique for identifying indications of nightside precipitation using the locally-trapped electron measurements by the CIRBE CubeSat. This study focuses on two main types of drivers for nightside precipitation: electron scattering by the curvature of magnetic field lines in the magnetotail current sheet and electron scattering by resonance with electromagnetic ion cyclotron (EMIC) waves. Using energy and pitch-angle resolved electron fluxes from the low-altitude ELFIN CubeSat, we reveal the features that distinguish between these two precipitation mechanisms based solely on locally-trapped flux measurements. Then we present measurements from four CIRBE orbits and demonstrate the applicability of the proposed technique to the investigation of nightside precipitation using CIRBE observations, enabling separation between precipitation induced by curvature scattering and EMIC waves in nearby regions. Our study underscores the feasibility of employing high-energy-resolution CIRBE measurements for detecting nightside precipitation of relativistic electrons. Additionally, we briefly discuss outstanding scientific questions about these precipitation patterns that could be addressed with CIRBE measurements.
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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 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 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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Journal articleAuestad H, Spensberger C, Marcheggiani A, et al., 2024, , Weather and Climate Dynamics, Vol: 5, Pages: 1269-1286, ISSN: 2698-4016
Latent 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, , ASTRONOMY & ASTROPHYSICS, Vol: 690, ISSN: 0004-6361
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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, , Radiocarbon: an international journal of cosmogenic isotope research, Vol: 66, Pages: 1054-1063, ISSN: 0033-8222
Radiocarbon 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 articleCuesta ME, Cummings AT, Livadiotis G, et al., 2024, , ASTROPHYSICAL JOURNAL, Vol: 973, ISSN: 0004-637X
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Journal articleRivera YJ, Badman ST, Stevens ML, et al., 2024, , ASTROPHYSICAL JOURNAL, Vol: 974, ISSN: 0004-637X
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