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Book chapterCargill P, 2023,
Sydney Chapman
, Oxford's Sedleian Professors of Natural Philosophy, Editors: Hollings, McCartney, Publisher: Oxford University Press, Pages: 157-176, ISBN: 9780192843210Sydney Chapman FRS was the Sedleian professor between 1946 and 1953. He was also one of the outstanding geophysicists of the twentieth century. His achievements cover a wide range of topics and include pioneering theory of transport in non-uniform gases, the first proposal of the nature of the ozone layer, and a comprehensive early theory of the nature of geomagnetic storms. The last of these forms the foundation of present-day studies of the Earth’s magnetosphere, and the impact of solar activity on society, referred to as space weather.
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Journal articleHorner G, Gryspeerdt E, 2023,
The evolution of deep convective systems and their associated cirrus outflows
, Atmospheric Chemistry and Physics, Vol: 23, Pages: 14239-14253, ISSN: 1680-7316Tropical deep convective clouds, particularly their large cirrus outflows, play an important role in modulating the energy balance of the Earth’s atmosphere. Whilst the cores of these deep convective clouds have a significant shortwave (SW) cooling effect, they dissipate quickly. Conversely, the thin cirrus that flow from these cores can persist for days after the core has dissipated, reaching hundreds of kilometers in extent. These thin cirrus have a potential for large warming in the tropics. Understanding the evolution of these clouds and how they change in response to anthropogenic emissions is therefore important to understand past and future climate change.This work uses a novel approach to investigate the evolution of tropical convective clouds by introducing the concept of ‘Time Since Convection’ (TSC). This is used to build a composite picture of the lifecycle of deep convection, from anvil cirrus to thin detrained cirrus. Cloud properties are a strong function of time since convection, showing decreases in the optical thickness, cloud top height, and cloud fraction over time. After an initial dissipation of the convective core, changes in thin cirrus cloud amount were seen beyond 200 hours from convection.Finally, in the initial stages of convection there was a large net negative cloud radiative effect (CRE). However, once the convective core had dissipated after 6–12 hours, the sign of the CRE flipped, and there was a sustained net warming CRE beyond 120 hours from the convective event. Changes are present in the cloud properties long after the main convective activities have dissipated, signalling the need to continue further analysis at longer time scales than previously studied.
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Journal articleSalvi P, Gregory JM, Ceppi P, 2023,
Time‐evolving radiative feedbacks in the historical period
, Journal of Geophysical Research: Atmospheres, Vol: 128, ISSN: 2169-8996We investigate the time-dependence of radiative feedback in the historical period (since the late 19th century), by analyzing experiments using coupled atmosphere–ocean climate models with historical greenhouse gas, anthropogenic aerosol, and natural forcings, each separately. We find that radiative feedback depends on forcing agent, primarily through the effect of cloud on shortwave radiation, because the various forcings cause different changes in global-mean tropospheric stability per degree of global-mean temperature change. The large time-variation of historical feedback driven by observed sea surface temperature change alone, with no forcing agents, is also consistent with tropospheric stability change, and differs from the similarly large and significant historical time-variation of feedback that is simulated in response to all forcing agents together. We show that the latter results from the varying relative sizes of individual forcings. We highlight that volcanic forcing is especially important for understanding the time-variation, because it stimulates particularly strong feedbacks that tend to reduce effective climate sensitivity. We relate this to stability changes due to enhanced surface temperature response in the Indo-Pacific warm pool.
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Journal articleRosu I-A, Grillakis M, Papadopoulos A, et al., 2024,
Fractal and Spectral Analysis of Recent Wildfire Scars in Greece
, FIRE TECHNOLOGY, ISSN: 0015-2684 -
Journal articleGeorge H, Malaspina DM, Goodrich K, et al., 2023,
Non-Lightning-Generated Whistler Waves in Near-Venus Space
, GEOPHYSICAL RESEARCH LETTERS, Vol: 50, ISSN: 0094-8276 -
Journal articleBlasl KA, Nakamura TKM, Nakamura R, et al., 2023,
Electron-Scale Reconnecting Current Sheet Formed Within the Lower-Hybrid Wave-Active Region of Kelvin-Helmholtz Waves
, GEOPHYSICAL RESEARCH LETTERS, Vol: 50, ISSN: 0094-8276 -
Journal articleShi P, Scime EE, Barbhuiya MH, et al., 2023,
Using Direct Laboratory Measurements of Electron Temperature Anisotropy to Identify the Heating Mechanism in Electron-Only Guide Field Magnetic Reconnection
, PHYSICAL REVIEW LETTERS, Vol: 131, ISSN: 0031-9007 -
Conference paperZhang Z, Desai R, Shebanits O, et al., 2023,
Cassini's floating potential in Titan's ionosphere: 3-D particle-in-cell simulations
, URSI GASS 2023, Publisher: IEEE, Pages: 1-4Accurate determination of Cassini’s spacecraft potential in Titan’s ionosphere is important for interpreting measurements by its low energy plasma instruments. Estimates of the floating potential varied significantly, however, between the various different plasma instruments. In this study we utilize 3-D particle-in-cell simulations to understand the key features of Cassini’s plasma interaction in Titan’s ionosphere. The spacecraft is observed to charge to negative potentials for all scenarios considered, and close agreement is found between the current onto the simulated Langmuir Probe and that observed in Titan’s ionosphere. These simulations are therefore shown to provide a viable technique for modeling spacecraft interacting with Titan’s dusty ionosphere.
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Journal articleGoodrich K, Cohen IJ, Schwartz S, et al., 2023,
The multi-point assessment of the kinematics of shocks (MAKOS)
, FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, Vol: 10, ISSN: 2296-987X -
Journal articleBandyopadhyay R, Meyer CM, Matthaeus WH, et al., 2023,
Estimates of Proton and Electron Heating Rates Extended to the Near-Sun Environment
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 955, ISSN: 2041-8205 -
Journal articlePaouris E, Vourlidas A, Kouloumvakos A, et al., 2023,
The Space Weather Context of the First Extreme Event of Solar Cycle 25, on 2022 September 5
, ASTROPHYSICAL JOURNAL, Vol: 956, ISSN: 0004-637X -
Journal articleAla-Lahti M, Pulkkinen TI, Ruohotie J, et al., 2023,
Multipoint Observations of the Dynamics at an ICME Sheath-Ejecta Boundary
, ASTROPHYSICAL JOURNAL, Vol: 956, ISSN: 0004-637X -
Journal articleGood SW, Rantala OK, Jylha A-SM, et al., 2023,
Turbulence Properties of Interplanetary Coronal Mass Ejections in the Inner Heliosphere: Dependence on Proton Beta and Flux Rope Structure
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 956, ISSN: 2041-8205 -
Journal articlePookkandy B, Graven H, Martin A, 2023,
Contemporary oceanic radiocarbon response to ocean circulation changes
, Climate Dynamics, Vol: 61, Pages: 3223-3235, ISSN: 0930-7575Radiocarbon (14C) is a valuable tracer of ocean circulation, owing to its natural decay over thousands of years and to its perturbation by nuclear weapons testing in the 1950s and 1960s. Previous studies have used 14C to evaluate models or to investigate past climate change. However, the relationship between ocean 14C and ocean circulation changes over the past few decades has not been explored. Here we use an Ocean-Sea-ice model (NEMO) forced with transient or fixed atmospheric reanalysis (JRA-55-do) and atmospheric 14C and CO2 boundary conditions to investigate the effect of ocean circulation trends and variability on 14C. We find that 14C/C (∆14C) variability is generally anti-correlated with potential density variability. The areas where the largest variability occurs varies by depth: in upwelling regions at the surface, at the edges of the subtropical gyres at 300 m depth, and in Antarctic Intermediate Water and North Atlantic Deep Water at 1000 m depth. We find that trends in the Atlantic Meridional Overturning Circulation may influence trends in ∆14C in the North Atlantic. In the high-variability regions the simulated variations are larger than typical ocean ∆14C measurement uncertainty of 2–5‰ suggesting that ∆14C data could provide a useful tracer of circulation changes.
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Journal articleFletcher LN, Cavalié T, Grassi D, et al., 2023,
Jupiter science Enabled by ESA's Jupiter Icy Moons Explorer
, Space Science Reviews, Vol: 219, ISSN: 0038-6308ESA's Jupiter Icy Moons Explorer (JUICE) will provide a detailed investigation of the Jovian system in the 2030s, combining a suite of state-of-the-art instruments with an orbital tour tailored to maximise observing opportunities. We review the Jupiter science enabled by the JUICE mission, building on the legacy of discoveries from the Galileo, Cassini, and Juno missions, alongside ground- and space-based observatories. We focus on remote sensing of the climate, meteorology, and chemistry of the atmosphere and auroras from the cloud-forming weather layer, through the upper troposphere, into the stratosphere and ionosphere. The Jupiter orbital tour provides a wealth of opportunities for atmospheric and auroral science: global perspectives with its near-equatorial and inclined phases, sampling all phase angles from dayside to nightside, and investigating phenomena evolving on timescales from minutes to months. The remote sensing payload spans far-UV spectroscopy (50-210 nm), visible imaging (340-1080 nm), visible/near-infrared spectroscopy (0.49-5.56 μm), and sub-millimetre sounding (near 530-625 GHz and 1067-1275 GHz). This is coupled to radio, stellar, and solar occultation opportunities to explore the atmosphere at high vertical resolution; and radio and plasma wave measurements of electric discharges in the Jovian atmosphere and auroras. Cross-disciplinary scientific investigations enable JUICE to explore coupling processes in giant planet atmospheres, to show how the atmosphere is connected to (i) the deep circulation and composition of the hydrogen-dominated interior; and (ii) to the currents and charged particle environments of the external magnetosphere. JUICE will provide a comprehensive characterisation of the atmosphere and auroras of this archetypal giant planet.
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Journal articleVuorinen L, Hietala H, Lamoury AT, et al., 2023,
Solar Wind Parameters Influencing Magnetosheath Jet Formation: Low and High IMF Cone Angle Regimes
, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 128, ISSN: 2169-9380 -
Journal articleColomban L, Agapitov OV, Krasnoselskikh V, et al., 2023,
Reconstruction of Polarization Properties of Whistler Waves From Two Magnetic and Two Electric Field Components: Application to Parker Solar Probe Measurements
, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 128, ISSN: 2169-9380 -
Journal articleZhou Y-J, He F, Zhang X-X, et al., 2023,
A radial standing Pc5-6 wave and its energy coupling with field line resonance within the dusk-sector magnetosphere
, JGR: Space Physics, Vol: 128, ISSN: 2169-9402Global ultra-low frequency (ULF) oscillations are believed to play a significant role in the mass, energy, and momentum transport within the Earth's magnetosphere. In this letter, we observe a ∼1.2 mHz radial standing wave in the dusk-sector magnetosphere accompanied by the field line resonance (FLR) on 16 July 2017. The frequency estimation from the simple box model also confirms the radial standing wave. The essential characteristics of FLR are concurrently identified at the dusk-sector magnetosphere and the conjugated ground location. Further, the radial standing wave dissipates energy into upper atmosphere to enhance the local aurora by coupling itself to the FLR. The magnetospheric dominant 1.2/1.1 mHz ULF waves plausibly correspond well with the discrete ∼1 mHz magnetosheath ion dynamic pressure/velocity oscillation, suggesting this radial standing wave and FLR in the flank magnetosphere may be triggered by the solar-wind and/or magnetosheath dynamic pressure/velocity fluctuations.
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Journal articleCollinson GA, Hietala H, Plaschke F, et al., 2023,
Shocklets and short large amplitude magnetic structures (SLAMS) in the high mach foreshock of Venus
, Geophysical Research Letters, Vol: 50, ISSN: 0094-8276Shocklets and short large-amplitude magnetic structures (SLAMS) are steepened magnetic fluctuations commonly found in Earth's upstream foreshock. Here we present Venus Express observations from the 26th of February 2009 establishing their existence in the steady-state foreshock of Venus, building on a past study which found SLAMS during a substantial disturbance of the induced magnetosphere. The Venusian structures were comparable to those reported near Earth. The 2 Shocklets had magnetic compression ratios of 1.23 and 1.34 with linear polarization in the spacecraft frame. The 3 SLAMS had ratios between 3.22 and 4.03, two of which with elliptical polarization in the spacecraft frame. Statistical analysis suggests SLAMS coincide with unusually high solar wind Alfvén mach-number at Venus (12.5, this event). Thus, while we establish Shocklets and SLAMS can form in the stable Venusian foreshock, they may be rarer than at Earth. We estimate a lower limit of their occurrence rate of ≳14%.
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Journal articleChatoutsidou SE, Saridaki A, Raisi L, et al., 2023,
Variations, seasonal shifts and ambient conditions affecting airborne microorganisms and particles at a southeastern Mediterranean site
, SCIENCE OF THE TOTAL ENVIRONMENT, Vol: 892, ISSN: 0048-9697- Author Web Link
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- Citations: 1
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Journal articleTelloni D, Romoli M, Velli M, et al., 2023,
Coronal Heating Rate in the Slow Solar Wind
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 955, ISSN: 2041-8205 -
Journal articleJebaraj IC, Krasnoselskikh V, Pulupa M, et al., 2023,
Fundamental-Harmonic Pairs of Interplanetary Type III Radio Bursts
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 955, ISSN: 2041-8205 -
Journal articleAlnussirat ST, Livi R, Larson DE, et al., 2023,
Dispersive Suprathermal Ion Events Observed by the Parker Solar Probe Mission
, ASTROPHYSICAL JOURNAL LETTERS, Vol: 954, ISSN: 2041-8205 -
Journal articleBessho N, Chen L-J, Hesse M, et al., 2023,
Electron Acceleration and Heating during Magnetic Reconnection in the Earth's Quasi-parallel Bow Shock
, ASTROPHYSICAL JOURNAL, Vol: 954, ISSN: 0004-637X -
Journal articleRomeo OM, Braga CR, Badman ST, et al., 2023,
Near-Sun In Situ and Remote-sensing Observations of a Coronal Mass Ejection and its Effect on the Heliospheric Current Sheet
, ASTROPHYSICAL JOURNAL, Vol: 954, ISSN: 0004-637X- Author Web Link
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- Citations: 1
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Journal articleTelloni D, Romoli M, Velli M, et al., 2023,
Energy Budget in the Solar Corona
, ASTROPHYSICAL JOURNAL, Vol: 954, ISSN: 0004-637X -
Journal articleHuang J, Kasper JC, Larson DE, et al., 2023,
The Temperature, Electron, and Pressure Characteristics of Switchbacks: Parker Solar Probe Observations
, ASTROPHYSICAL JOURNAL, Vol: 954, ISSN: 0004-637X -
Journal articleBoucher O, Bellouin N, Clark H, et al., 2023,
Comparison of actual and time-optimized flight trajectories in the context of the in-service aircraft for a global observing system (IAGOS) programme
, Aerospace, Vol: 10, ISSN: 2226-4310Airlines optimize flight trajectories in order to minimize their operational costs, of which fuel consumption is a large contributor. It is known that flight trajectories are not fuel-optimal because of airspace congestion and restrictions, safety regulations, bad weather and other operational constraints. However, the extent to which trajectories are not fuel-optimal (and therefore CO2-optimal) is not well known. In this study, we present two methods for optimizing the flight cruising time by taking best advantage of the wind pattern at a given flight level and for constant airspeed. We test these methods against actual flight trajectories recorded under the In-service Aircraft for a Global Observing System (IAGOS) programme. One method is more robust than the other (computationally faster) method, but when successful, the two methods agree very well with each other, with optima generally within the order of 0.1%. The IAGOS actual cruising trajectories are on average 1% longer than the computed optimal for the transatlantic route, which leaves little room for improvement given that by construction the actual trajectory cannot be better than our optimum. The average degree of non-optimality is larger for some other routes and can be up to 10%. On some routes, there are also outlier flights that are not well optimized; however, the reason for this is not known.
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Journal articleKang SM, Ceppi P, Yu Y, et al., 2023,
Recent global climate feedback controlled by Southern Ocean cooling
, Nature Geoscience, Vol: 16, Pages: 775-780, ISSN: 1752-0894The magnitude of global warming is controlled by climate feedbacks associated with various aspects of the climate system, such as clouds. The global climate feedback is the net effect of these feedbacks, and its temporal evolution is thought to depend on the tropical Pacific sea surface temperature pattern. However, current coupled climate models fail to simulate the pattern observed in the Pacific between 1979 and 2013 and its associated anomalously negative feedback. Here we demonstrate a mechanism whereby the Southern Ocean controls the global climate feedback. Using climate model experiments in which Southern Ocean sea surface temperatures are restored to observations, we show that accounting for recent Southern Ocean cooling—which is absent in coupled climate models—halves the bias in the global climate feedback by removing the cloud component bias. This global impact is mediated by a teleconnection to the Southeast Pacific, where remote sea surface temperature anomalies cause a strong stratocumulus cloud feedback. We propose that this Southern Ocean-driven pattern effect is underestimated in most climate models, owing to an overly weak stratocumulus cloud feedback. Addressing this bias may shift climate sensitivities to higher values than currently simulated as the Southern Ocean undergoes accelerated warming in future projections.
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Journal articleBasar G, Ozturk IK, Erdogan H, et al., 2023,
New even parity fine structure energy levels of atomic vanadium
, SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY, Vol: 207, ISSN: 0584-8547
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