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  • Journal article
    Dumont V, Bowen TA, Roglans R, Dobler G, Sharma MS, Karpf A, Bale SD, Wickenbrock A, Zhivun E, Kornack T, Wurtele JS, Budker Det al., 2022,

    Do cities have a unique magnetic pulse?

    , JOURNAL OF APPLIED PHYSICS, Vol: 131, ISSN: 0021-8979
  • Journal article
    Gangopadhyay A, Sparks NJ, Toumi R, Seshadri AKet al., 2022,

    Risk assessment of wind droughts over India

    , Current Science, Vol: 122, Pages: 1145-1153, ISSN: 0011-3891

    Wind power growth makes it essential to simulateweather variability and its impacts on the electricitygrid. Low-probability, high-impact weather events suchas a wind drought are important but difficult to identify based on limited historical datasets. A stochasticweather generator, Imperial College Weather Generator (IMAGE), is employed to identify extreme eventsthrough long-period simulations. IMAGE capturesmean, spatial correlation and seasonality in wind speedand estimates return periods of extreme wind eventsover India. Simulations show that when Rajasthan experiences wind drought, southern India continues tohave wind, and vice versa. Regional grid-scale winddroughts could be avoided if grids are strongly interconnected across the country.
  • Journal article
    Phan TD, Verniero JL, Larson D, Lavraud B, Drake JF, Øieroset M, Eastwood JP, Bale SD, Livi R, Halekas JS, Whittlesey PL, Rahmati A, Stansby D, Pulupa M, MacDowall RJ, Szabo PA, Koval A, Desai M, Fuselier SA, Velli M, Hesse M, Pyakurel PS, Maheshwari K, Kasper JC, Stevens JM, Case AW, Raouafi NEet al., 2022,

    Parker solar probe observations of solar wind energetic proton beams produced by magnetic reconnection in the near‐sun heliospheric current sheet

    , Geophysical Research Letters, Vol: 49, ISSN: 0094-8276

    We report observations of reconnection exhausts in the Heliospheric Current Sheet (HCS) during Parker Solar Probe Encounters 08 and 07, at 16 Rs and 20 Rs, respectively. Heliospheric current sheet (HCS) reconnection accelerated protons to almost twice the solar wind speed and increased the proton core energy by a factor of ∼3, due to the Alfvén speed being comparable to the solar wind flow speed at these near-Sun distances. Furthermore, protons were energized to super-thermal energies. During E08, energized protons were found to have leaked out of the exhaust along separatrix field lines, appearing as field-aligned energetic proton beams in a broad region outside the HCS. Concurrent dropouts of strahl electrons, indicating disconnection from the Sun, provide further evidence for the HCS being the source of the beams. Around the HCS in E07, there were also proton beams but without electron strahl dropouts, indicating that their origin was not the local HCS reconnection exhaust.
  • Journal article
    Schwartz SJ, Goodrich KA, Wilson III LB, Turner DL, Trattner K, Kucharek H, Gingell I, Fuselier SA, Cohen IJ, Madanian H, Ergun RE, Gershman DJ, Strangeway RJet al., 2022,

    Energy partition at collisionless supercritical quasiperpendicular shocks
  • Journal article
    Murray-Watson RJ, Gryspeerdt E, 2022,

    Stability-dependent increases in liquid water with droplet number in the Arctic

    , Atmospheric Chemistry and Physics, Vol: 22, Pages: 5743-5756, ISSN: 1680-7316

    The effects of aerosols on cloud microphysical properties are a large source of uncertainty when assessing anthropogenic climate change. The aerosol–cloud relationship is particularly unclear in high-latitude polar regions due to a limited number of observations. Cloud liquid water path (LWP) is an important control on cloud radiative properties, particularly in the Arctic, where clouds play a central role in the surface energy budget. Therefore, understanding how aerosols may alter cloud LWP is important, especially as aerosol sources such as industry and shipping move further north in a warming Arctic.Using satellite data, this work investigates the effects of aerosols on liquid Arctic clouds over open ocean by considering the relationship between cloud droplet number concentration (Nd) and LWP, an important component of the aerosol–LWP relationship. The LWP response to Nd varies significantly across the region, with increases in LWP with Nd observed at very high latitudes in multiple satellite datasets, with this positive signal observed most strongly during the summer months. This result is in contrast to the negative response typically seen in global satellite studies and previous work on Arctic clouds showing little LWP response to aerosols.The lower tropospheric stability (LTS) was found to be an important control on the spatial variations in LWP response, strongly influencing the sign and magnitude of the Nd–LWP relationship, with increases in LWP in high-stability environments. The influence of humidity varied depending on the stability, with little impact at low LTS but a strong influence at high LTS. The mean Nd state does not dominate the LWP response, despite the non-linearities in the relationship. As the Nd–LWP sensitivity changed from positive to negative when moving from high- to low-LTS environments, this work shows evidence of a temperature-dependent aerosol indirect effect. Additionally, the LWP–LTS relationship chan
  • Conference paper
    Deca J, Stephenson P, Divin A, Henri P, Galand Met al., 2022,

    A Fully Kinetic Perspective on Weakly Active Comets: Symmetric versus Asymmetric Outgassing

    , Publisher: Copernicus GmbH

    <jats:p>&amp;lt;p&amp;gt;For more than two years, ESA&amp;amp;#8217;s Rosetta mission measured the complex and ever-evolving plasma environment surrounding comet 67P/Churyumov-Gerasimenko. In this work, we explore the structure and dynamics of the near-comet plasma environment at steady state, comparing directly the results of a spherically symmetric Haser model and an asymmetric outgassing profile based on the measurements from the ROSINA instrument onboard Rosetta during 67P&amp;amp;#8217;s weakly outgassing stages. Using a fully kinetic semi-implicit particle-in-cell code, we are able to characterise (1) the various ion and electron populations and their interactions, and (2) the implications to the mass-loading process caused by taking into account asymmetric outgassing. Our model complements observations by providing a full 3D picture that is directly relevant to help interpret the measurements made by the Rosetta Plasma Consortium instruments. In addition, understanding such details better is key to help disentangle the physical drivers active in the plasma environment of comets visited by future exploration missions.&amp;lt;/p&amp;gt;</jats:p>
  • Journal article
    Hellinger P, Montagud-Camps V, Franci L, Matteini L, Papini E, Verdini A, Landi Set al., 2022,

    Ion-scale Transition of Plasma Turbulence: Pressure-Strain Effect

    , ASTROPHYSICAL JOURNAL, Vol: 930, ISSN: 0004-637X
  • Journal article
    Nieves-Chinchilla T, Alzate N, Cremades H, Rodriguez-Garcia L, Dos Santos LFG, Narock A, Xie H, Szabo A, Palmerio E, Krupar V, Pulupa M, Lario D, Stevens ML, Wilson LB, Kwon R-Y, Mays ML, St Cyr OC, Hess P, Reeves KK, Seaton DB, Niembro T, Bale SD, Kasper JCet al., 2022,

    Direct First Parker Solar Probe Observation of the Interaction of Two Successive Interplanetary Coronal Mass Ejections in 2020 November

    , ASTROPHYSICAL JOURNAL, Vol: 930, ISSN: 0004-637X
    • Cite
    • Citations: 17
  • Journal article
    Akbari H, Newman D, Fowler C, Pfaff R, Andersson L, Malaspina D, Schwartz S, Ergun R, McFadden J, Mitchell D, Halekas J, Rowland Det al., 2022,

    Micro-Scale Plasma Instabilities in the Interaction Region of the Solar Wind and the Martian Upper Atmosphere

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380
  • Journal article
    Palmerio E, Lee CO, Mays ML, Luhmann JG, Lario D, Sanchez-Cano B, Richardson IG, Vainio R, Stevens ML, Cohen CMS, Steinvall K, Mostl C, Weiss AJ, Nieves-Chinchilla T, Li Y, Larson DE, Heyner D, Bale SD, Galvin AB, Holmstrom M, Khotyaintsev Y, Maksimovic M, Mitrofanov IGet al., 2022,

    CMEs and SEPs During November-December 2020: A Challenge for Real-Time Space Weather Forecasting

    , SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS, Vol: 20
    • Cite
    • Citations: 22
  • Journal article
    Archer M, Waters C, Dewan S, Foster S, Portas Aet al., 2022,

    GC Insights: Space sector careers resources in the UK need a greater diversity of roles

    , Geoscience Communication, Vol: 5, Pages: 119-123, ISSN: 2569-7110

    Educational research highlights that improved careers education is needed to increase participation in science, technology, engineering, and mathematics (STEM). Current UK careers resources concerning the space sector, however, are found to perhaps not best reflect the diversity of roles present and may in fact perpetuate misconceptions about the usefulness of science. We, therefore, compile a more diverse set of space-related jobs, which will be used in the development of a new space careers resource.
  • Journal article
    Bale SD, 2022,

    Eugene N. Parker (1927-2022)

    , SCIENCE, Vol: 376, Pages: 461-461, ISSN: 0036-8075
  • Journal article
    Salvi P, Ceppi P, Gregory JM, 2022,

    Interpreting differences in radiative feedbacks from aerosols versus greenhouse gases

    , Geophysical Research Letters, Vol: 49, Pages: 1-9, ISSN: 0094-8276

    Experiments with seven Coupled Model Intercomparison Project phase 6 models were used to assess the climate feedback parameter for net historical, historical greenhouse gas (GHG) and anthropogenic aerosol forcings. The net radiative feedback is found to be more amplifying (higher effective climate sensitivity) for aerosol than GHG forcing, and hence also less amplifying for net historical (GHG + aerosol) than GHG only. We demonstrate that this difference is consistent with their different latitudinal distributions. Historical aerosol forcing is most pronounced in northern extratropics, where the boundary layer is decoupled from the free troposphere, so the consequent temperature change is confined to low altitude and causes low-level cloud changes. This is caused by change in stability, which also affects upper-tropospheric clear-sky emission, affecting both shortwave and longwave radiative feedbacks. This response is a feature of extratropical forcing generally, regardless of its sign or hemisphere.
  • Journal article
    Brown ZL, Medvedev AS, Starichenko ED, Koskinen TT, Mueller-Wodarg ICFet al., 2022,

    Evidence for Gravity Waves in the Thermosphere of Saturn and Implications for Global Circulation

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 49, ISSN: 0094-8276
  • Journal article
    Warwick L, Brindley H, Di Roma A, Fox S, Havemann S, Murray J, Oetjen H, Price H, Schüttemeyer D, Sgheri L, Tiddeman Det al., 2022,

    Retrieval of tropospheric water vapour from airborne far-infrared measurements: a case study

    , Journal of Geophysical Research: Atmospheres, Vol: 127, ISSN: 2169-897X

    We describe studies undertaken in support of the Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission, ESA’s ninth Earth Explorer, designed to investigate whether airborne observations of far-infrared radiances can provide beneficial information on mid and upper tropospheric water vapour concentrations.Initially we perform a joint temperature and water vapour retrieval and show that the water vapour retrieval exploiting far-infrared measurements from the Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) shows improvement over the a-priori Unified Model global forecast when compared to in situ dropsonde measurements. For this case the improvement is particularly noticeable in the mid-upper troposphere. Equivalent retrievals using mid-infrared radiances measured by the Airborne Research Interferometer Evaluation System (ARIES) show much reduced performance, with the degrees of freedom for signal (DFS), reduced by a factor of almost 2. Further sensitivity studies show that this advantage is decreased, but still present when the spectral resolution of the TAFTS measurements is reduced to match that of ARIES.The beneficial role of the far infrared for this case is further confirmed by performing water vapour only retrievals using ARIES and TAFTS individually, and then in combination. We find that the combined retrieval has a DFS value of 6.7 for water vapour, marginally larger than that obtained for the TAFTS retrieval and almost twice as large as that obtained for ARIES.These results provide observational support of theoretical studies highlighting the potential improvement that far-infrared observations could bring for the retrieval of tropospheric water vapour.
  • Journal article
    Dimmock AP, Khotyaintsev YV, Lalti A, Yordanova E, Edberg NJT, Steinvall K, Graham DB, Hadid LZ, Allen RC, Vaivads A, Maksimovic M, Bale SD, Chust T, Krasnoselskikh V, Kretzschmar M, Lorfevre E, Plettemeier D, Soucek J, Steller M, Stverak S, Travnicek P, Vecchio A, Horbury TS, O'Brien H, Evans V, Angelini Vet al., 2022,

    Analysis of multiscale structures at the quasi-perpendicular Venus bow shock Results from Solar Orbiter's first Venus flyby

    , ASTRONOMY & ASTROPHYSICS, Vol: 660, ISSN: 0004-6361
  • Journal article
    Eggington J, Desai R, Mejnertsen L, Chittenden J, Eastwood Jet al., 2022,

    Time-varying magnetopause reconnection during sudden commencement: global MHD simulations

    , Journal of Geophysical Research: Space Physics, Vol: 127, ISSN: 2169-9380

    In response to a solar wind dynamic pressure enhancement, the compression of the magnetosphere generates strong ionospheric signatures and a sharp variation in the ground magnetic field, termed sudden commencement (SC). Whilst such compressions have also been associated with a contraction of the ionospheric polar cap due to the triggering of reconnection in the magnetotail, the effect of any changes in dayside reconnection is less clear and is a key component in fully understanding the system response. In this study we explore the time-dependent nature of dayside coupling during SC by performing global simulations using the Gorgon MHD code, and impact the magnetosphere with a series of interplanetary shocks with different parameters. We identify the location and evolu tion of the reconnection region in each case as the shock propagates through the magnetosphere, finding strong enhancement in the dayside reconnection rate and prompt expansion of the dayside polar cap prior to the eventual triggering of tail reconnection. This effect pervades for a variety of IMF orientations, and the reconnection rate is most enhanced for events with higher dynamic pressure. We explain this by repeating the simulations with a large explicit resistivity, showing that compression of the magnetosheath plasma near the propagating shock front allows for reconnection of much greater intensity and at different locations on the dayside magnetopause than during typical solar wind conditions. The results indicate that the dynamic behaviour of dayside coupling may render steady models of reconnection inaccurate during the onset of a severe space weather event.
  • Journal article
    Zhao L-L, Zank GP, Telloni D, Stevens M, Kasper JC, Bale SDet al., 2022,

    The Turbulent Properties of the Sub-Alfvenic Solar Wind Measured by the Parker Solar Probe

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 928, ISSN: 2041-8205
    • Cite
    • Citations: 34
  • Journal article
    Rovithakis A, Grillakis MG, Seiradakis KD, Giannakopoulos C, Karali A, Field R, Lazaridis M, Voulgarakis Aet al., 2022,

    Future climate change impact on wildfire danger over the Mediterranean: the case of Greece

    , Environmental Research Letters, Vol: 17, ISSN: 1748-9326

    Recent studies have shown that temperature and precipitation in the Mediterranean are expected to change, contributing to longer and more intense summer droughts that even extend out of season. In connection to this, the frequency of forest fire occurrence and intensity will likely increase. In the present study, the changes in future fire danger conditions are assessed for the different regions of Greece using the Canadian fire weather index (FWI). Gridded future climate output as estimated from three regional climate models from the Coordinated Regional Downscaling Experiment are utilized. We use three representative concentration pathways (RCPs) consisting of an optimistic emissions scenario where emissions peak and decline beyond 2020 (RCP2.6), a middle-of-the-road scenario (RCP4.5) and a pessimistic scenario, in terms of mitigation where emissions continue to rise throughout the century (RCP8.5). Based on established critical fire FWI threshold values for Greece, the future change in days with critical fire danger were calculated for different areas of Greece domains. The results show that fire danger is expected to progressively increase in the future especially in the high-end climate change scenario with southern and eastern regions of Greece expected to have up to 40 additional days of high fire danger relative to the late 20th century, on average. Crete, the Aegean Islands, the Attica region, as well as parts of Peloponnese are predicted to experience a stronger increase in fire danger.
  • Journal article
    Grillakis M, Voulgarakis A, Rovithakis A, Seiradakis KD, Koutroulis A, Field RD, Kasoar M, Papadopoulos A, Lazaridis Met al., 2022,

    Climate drivers of global wildfire burned area

    , Environmental Research Letters, Vol: 17, Pages: 1-10, ISSN: 1748-9326

    Wildfire is an integral part of the Earth system, but at the same time it can pose serious threats to human society and to certain types of terrestrial ecosystems. Meteorological conditions are a key driver of wildfire activity and extent, which led to the emergence of the use of fire danger indices that depend solely on weather conditions. The Canadian Fire Weather Index (FWI) is a widely used fire danger index of this kind. Here, we evaluate how well the FWI, its components, and the climate variables from which it is derived, correlate with observation-based burned area (BA) for a variety of world regions. We use a novel technique, according to which monthly BA are grouped by size for each Global Fire Emissions Database (GFED) pyrographic region. We find strong correlations of BA anomalies with the FWI anomalies, as well as with the underlying deviations from their climatologies for the four climate variables from which FWI is estimated, namely, temperature, relative humidity, precipitation, and wind. We quantify the relative sensitivity of the observed BA to each of the four climate variables, finding that this relationship strongly depends on the pyrographic region and land type. Our results indicate that the BA anomalies strongly correlate with FWI anomalies at a GFED region scale, compared to the strength of the correlation with individual climate variables. Additionally, among the individual climate variables that comprise the FWI, relative humidity and temperature are the most influential factors that affect the observed BA. Our results support the use of the composite fire danger index FWI, as well as its sub-indices, the Build-Up Index (BUI) and the Initial Spread Index (ISI), comparing to single climate variables, since they are found to correlate better with the observed forest or non-forest BA, for the most regions across the globe.
  • Journal article
    Lotekar AB, Vasko IY, Phan T, Bale SD, Bowen TA, Halekas J, Artemyev A, Khotyaintsev Y, Mozer FSet al., 2022,

    Kinetic-scale Current Sheets in Near-Sun Solar Wind: Properties, Scale-dependent Features and Reconnection Onset

    , ASTROPHYSICAL JOURNAL, Vol: 929, ISSN: 0004-637X
    • Cite
    • Citations: 30
  • Journal article
    Stephenson P, Galand M, Deca J, Henri P, Carnielli Get al., 2022,

    A collisional test particle model of electrons at a comet

    , Monthly Notices of the Royal Astronomical Society, Vol: 511, Pages: 4090-4108, ISSN: 0035-8711

    We have developed the first 3D collisional model of electrons at a comet, which we use to examine the impact of electron-neutral collisions in the weakly outgassing regime. The test-particle Monte Carlo model uses electric and magnetic fields from a fully kinetic Particle-in-Cell (PiC) model as an input. In our model, electrons originate from the solar wind or from ionization of the neutral coma, either by electron impact or absorption of an extreme ultraviolet photon. All relevant electron-neutral collision processes are included in the model including elastic scattering, excitation, and ionization. Trajectories of electrons are validated against analytically known drifts and the stochastic energy degradation used in the model is compared to the continuous slowing down approximation. Macroscopic properties of the solar wind and cometary electron populations, such as density and temperature, are validated with simple known cases and via comparison with the collisionless PiC model. We demonstrate that electrons are trapped close to the nucleus by the ambipolar electric field, causing an increase in the efficiency of electron-neutral collisions. Even at a low-outgassing rate (Q = 1026 s−1), electron-neutral collisions are shown to cause significant cooling in the coma. The model also provides a multistep numerical framework that is used to assess the influence of the electron-to-ion mass ratio, enabling access to electron dynamics with a physical electron mass.
  • Journal article
    Koller F, Temmer M, Preisser L, Plaschke F, Geyer P, Jian LK, Roberts OW, Hietala H, LaMoury ATet al., 2022,

    Magnetosheath jet occurrence rate in relation to CMEs and SIRs

    , Journal of Geophysical Research: Space Physics, Vol: 127, ISSN: 2169-9380

    Magnetosheath jets constitute a significant coupling effect between the solar wind (SW) and the magnetosphere of the Earth. In order to investigate the effects and forecasting of these jets, we present the first-ever statistical study of the jet production during large-scale SW structures like coronal mass ejections (CMEs), stream interaction regions (SIRs) and high speed streams (HSSs). Magnetosheath data from Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft between January 2008 and December 2020 serve as measurement source for jet detection. Two different jet definitions were used to rule out statistical biases induced by our jet detection method. For the CME and SIR + HSS lists, we used lists provided by literature and expanded on incomplete lists using OMNI data to cover the time range of May 1996 to December 2020. We find that the number and total time of observed jets decrease when CME-sheaths hit the Earth. The number of jets is lower throughout the passing of the CME-magnetic ejecta (ME) and recovers quickly afterward. On the other hand, the number of jets increases during SIR and HSS phases. We discuss a few possibilities to explain these statistical results.
  • Journal article
    de Wit TD, Krasnoselskikh VV, Agapitov O, Froment C, Larosa A, Bale SD, Bowen T, Goetz K, Harvey P, Jannet G, Kretzschmar M, MacDowall RJ, Malaspina D, Martin P, Page B, Pulupa M, Revillet Cet al., 2022,

    First Results From the SCM Search-Coil Magnetometer on Parker Solar Probe

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380
    • Cite
    • Citations: 17
  • Journal article
    Martinovic MM, Dordevic AR, Klein KG, Maksimovic M, Issautier K, Liu M, Pulupa M, Bale SD, Halekas JS, McManus MDet al., 2022,

    Plasma Parameters From Quasi-Thermal Noise Observed by Parker Solar Probe: A New Model for the Antenna Response

    , JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 127, ISSN: 2169-9380
  • Journal article
    Lewis ZM, Wild JA, Allcock M, Walach M-Tet al., 2022,

    Assessing the Impact of Weak and Moderate Geomagnetic Storms on UK Power Station Transformers

    , SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS, Vol: 20
  • Journal article
    Myhre G, Samset B, Forster PM, Hodnebrog Ø, Sandstad M, Mohr CW, Sillmann J, Stjern CW, Andrews T, Boucher O, Faluvegi G, Iversen T, Lamarque J-F, Kasoar M, Kirkevåg A, Kramer R, Liu L, Mülmenstädt J, Olivié D, Quaas J, Richardson TB, Shawki D, Shindell D, Smith C, Stier P, Tang T, Takemura T, Voulgarakis A, Watson-Parris Det al., 2022,

    Scientific data from precipitation driver response model intercomparison project

    , Scientific Data, Vol: 9, Pages: 123-123, ISSN: 2052-4463

    This data descriptor reports the main scientific values from General Circulation Models (GCMs) in the Precipitation Driver and Response Model Intercomparison Project (PDRMIP). The purpose of the GCM simulations has been to enhance the scientific understanding of how changes in greenhouse gases, aerosols, and incoming solar radiation perturb the Earth's radiation balance and its climate response in terms of changes in temperature and precipitation. Here we provide global and annual mean results for a large set of coupled atmospheric-ocean GCM simulations and a description of how to easily extract files from the dataset. The simulations consist of single idealized perturbations to the climate system and have been shown to achieve important insight in complex climate simulations. We therefore expect this data set to be valuable and highly used to understand simulations from complex GCMs and Earth System Models for various phases of the Coupled Model Intercomparison Project.
  • Conference paper
    Gryspeerdt E, Louro Coelho M, Smith T, Suarez De La Fuente S, Quilelli Correa Rocha Ribeiro R, van Reeuwijk Met al., 2022,

    Measuring cloud sensitivity to aerosols at a global scale using isolated aerosol sources

    <jats:p>&amp;lt;p&amp;gt;The sensitivity of clouds to anthropogenic aerosol perturbations remains one of the largest uncertainties in the human forcing of the climate system. A key difficulty is in isolating the impact of aerosols from large-scale covariability of aerosol and cloud properties. Natural experiments, where aerosol is produced independently of the cloud and meteorological properties, provide a pathway to address this issue. These aerosol sources often modify cloud properties, leaving linear cloud features known as shiptracks (when formed by a ship) or pollution tracks (more generally).&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;In this work, we use a database of point sources of aerosol over both land and ocean to identify clouds that are sensitive to aerosol and to measure their response. Using a neural network to identify when a point source is modifying the cloud, we are able to measure the sensitivity of individual clouds to aerosol at a global scale, looking at over 400 million cases.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;We find the probability of track formation is strongly dependent on the background cloud and meteorological state, similar to previous regional studies. With our global database, we identify regions that are strongly susceptible to aerosol perturbations, even where aerosol sources are rare. We find that there are several regions that are highly susceptible to aerosol, but that have been previously overlooked due to a low frequency of pollution tracks. &amp;amp;#160; &amp;amp;#160;&amp;lt;/p&amp;gt;</jats:p>
  • Journal article
    Wang S, Toumi R, 2022,

    More tropical cyclones are striking coasts with major intensities at landfall

    , Scientific Reports, Vol: 12, ISSN: 2045-2322

    In this study we show that the number of annual global tropical cyclone (TC) landfalls with major landfall intensity (LI≥50 m s-1) has nearly doubled from 1982 to 2020. The lifetime maximum intensity (LMI) of global major landfalling TCs has been increasing by 0.8 m s-1 per decade (p<0.05), but this significance of intensity change disappears at landfall (0.3 m s-1 per decade, p=0.69). The lack of a significant LI trend is caused by the much larger variance of LI than that of LMI in all basins and explains why a significant count change of TCs with major intensity at landfall has only now emerged. Basin-wide TC trends of intensity and spatial distribution have been reported, but this long-term major TC landfall count change may be the most socio-economic significant.
  • Journal article
    Matteini L, Hellinger P, Landi S, Franci L, Tenerani A, Velli Met al., 2022,

    Kinetic Instabilities from Ion Beams and Differential Streaming in the Close-Sun Solar Wind: Hybrid Expanding Simulations

    <jats:p>&amp;lt;p&amp;gt;Parker Solar Probe observations in the inner heliosphere have demonstrated that non-thermal features in solar wind ion distributions are particularly enhanced and dominant in the close-Sun environment. Proton beams and large differential flows of alpha particles are ubiquitously observed, also in slow, though Alfv&amp;amp;#233;nic, streams, qualitatively at odds with typical observations at 1AU, where non-Maxwellian features are usually less apparent in the slow solar wind. All this reinforces the idea, also supported by past Helios and Ulysses explorations, that preferential ion heating and acceleration take place already in the Corona and signatures of the kinetic processes involved are gradually washed out during expansion. To explore further properties of ion differential streaming during expansion, as well as associated kinetic instabilities and their possible role in plasma heating, we perform expanding box hybrid simulations of a multi-species solar wind composed by proton core, beam and alpha particles, focussing on the role of wave-particle interactions in shaping distribution functions and controlling relative drifts. Radial trends and typical distributions found in simulations are then compared with PSP and Solar Orbiter observations in the inner Heliosphere.&amp;lt;/p&amp;gt;</jats:p>

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