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  • Journal article
    Howes GG, Verniero JL, Larson DE, Bale SD, Kasper JC, Goetz K, Klein KG, Whittlesey PL, Livi R, Rahmati A, Chen CHK, Wilson LB, Alterman BL, Wicks RTet al., 2022,

    Revolutionizing Our Understanding of Particle Energization in Space Plasmas Using On-Board Wave-Particle Correlator Instrumentation

    , FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, Vol: 9, ISSN: 2296-987X
  • Conference paper
    Glassmeier F, Hoffmann F, Feingold G, Gryspeerdt E, van Hooft A, Yamaguchi T, Johnson JS, Carslaw KSet al., 2022,

    Gaussian-process emulation for integrating data-driven aerosol-cloud physics from simulation, satellite, and ground-based data

    <jats:p>&amp;lt;p&amp;gt;Data-driven quantification and parameterization of cloud physics in general, and of aerosol-cloud interactions in particular, rely on input data from observations or detailed simulations. These data sources have complementary limitations in terms of their spatial and temporal coverage and resolution; simulation data has the advantage of readily providing causality but cannot represent the full process complexity. In order to base data-driven approaches on comprehensive information, we therefore need ways to integrate different data sources.&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;We discuss how the classical statistical technique of Gaussian-process emulation can be combined with specifically initialized ensembles of detailed cloud simulations (large-eddy simulations, LES) to provide a framework for evaluating data-driven descriptions of cloud characteristics and processes across different data sources. We specifically illustrate this approach for integrating LES and satellite data of aerosol-cloud interactions in subtropical stratocumulus cloud decks. We furthermore explore the extension of our framework to ground-based observations of Arctic mixed-phase clouds.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;&amp;lt;strong&amp;gt;References:&amp;lt;/strong&amp;gt;&amp;lt;/p&amp;gt;&amp;lt;ul&amp;gt;&amp;lt;li&amp;gt;Glassmeier, F., F. Hoffmann, J. S. Johnson, T. Yamaguchi, K. S. Carslaw and G. Feingold (2019): &amp;amp;#8220;An emulator approach to stratocumulus susceptibility&amp;amp;#8221;, Atmos. Chem. Phys., 19, 10191- 10203, doi: 10.5194/acp-19-10191-2019&amp;lt;/li&amp;gt;&amp;lt;li&amp;gt;Hoffmann, F., F. Glassmeier, T. Yamaguchi and G. Feingold (2020)
  • Journal article
    Good SW, Hatakka LM, Ala-Lahti M, Soljento JE, Osmane A, Kilpua EKJet al., 2022,

    Cross helicity of interplanetary coronal mass ejections at 1 au

    , MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Vol: 514, Pages: 2425-2433, ISSN: 0035-8711
  • Journal article
    Vasko IY, Mozer FS, Bale SD, Artemyev Aet al., 2022,

    Ion-Acoustic Waves in a Quasi-Perpendicular Earth's Bow Shock

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 49, ISSN: 0094-8276
  • Journal article
    Ergun RE, Usanova ME, Turner DL, Stawarz Jet al., 2022,

    Bursty bulk flow turbulence as a source of energetic particles to the outer radiation belt

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

    We report observations of a Bursty Bulk Flow (BBF) penetrating close to the outer edge of the radiation belt. The turbulent BBF braking region is characterized by ion velocity fluctuations, magnetic field (B) variations, and intense electric fields (E). In this event, energetic (>100 keV) electron and ion fluxes are appreciably enhanced. Importantly, fluctuations in energetic electrons and ions suggest local energization. Using correlation distances and other observed characteristics of turbulent E, test-particle simulations support local energization by E that favors higher-energy electrons and leads to an enhanced energetic shoulder and tail in the electron distributions. The energetic shoulder and tail could be amplified to MeV energies by adiabatic transport into the radiation belt where |B| is higher. This analysis suggests that turbulence generated by BBFs can, in part, supply energetic particles to the outer radiation belt and that turbulence can be a significant contributor to particle acceleration.
  • Journal article
    Breul P, Ceppi P, Shepherd TG, 2022,

    Relationship between southern hemispheric jet variability and forced response: the role of the stratosphere

    , Weather and Climate Dynamics, Vol: 3, Pages: 645-658, ISSN: 2698-4016

    Climate models show a wide range of southern hemispheric jet responses to greenhouse gas forcing. One approach to constrain the future jet response is by utilising the fluctuation–dissipation theorem (FDT) which links the forced response to internal variability timescales, with the Southern Annular Mode (SAM) the most dominant mode of variability of the southern hemispheric jet. We show that interannual stratospheric variability approximately doubles the SAM timescale during austral summer in both re-analysis data and models from the Coupled Model Intercomparison Project, Phases 5 (CMIP5) and 6 (CMIP6). Using a simple barotropic model, we demonstrate how the enhanced SAM timescale subsequently leads to an overestimate of the forced jet response based on the FDT, and we introduce a method to correct for the stratospheric influence. This result helps to resolve a previously identified discrepancy between the seasonality of jet response and the internal variability timescale. However, even after accounting for this influence, the SAM timescale cannot explain inter-model differences in the forced jet shift across CMIP models during austral summer.
  • Journal article
    Wang S, Toumi R, 2022,

    An analytic model of the tropical cyclone outer size

    , npj Climate and Atmospheric Science, Vol: 5, ISSN: 2397-3722

    There are simple conceptual models of tropical cyclone intensification and potential intensity. However, such a framework has been lacking to describe the evolution of the outer circulation. An analytic growth model of the tropical cyclone outer size is derived from the angular momentum equation. The growth model fits a full-physics idealized tropical cyclone simulation. The lifecycle composite of the best-track outer size growth shows a strong super-linear nature, which supports an exponential growth as predicted by the growth model. The climatology of outer size growth measured by the radius of gale-force wind in the North Atlantic and Eastern Pacific during the period 2004–2017, can be understood in terms of four growth factors of the model: the initial size, the growth duration, the mean growth latitude, and the mean top-of-boundary-layer effective local inflow angle. All four variables are significantly different between the two basins. The observed lifetime maximum size follows a lognormal distribution, which is in line with the law of the proportionate effect of this exponential growth model. The growth model fits the observed outer size well in global basins. The time constant of the exponential size growth is approximately equal to the product of the Coriolis parameter and the mean effective inflow angle above the boundary layer. Further sensitivity experiments with the growth model suggest that the interannual variability of the global lifetime maximum size is largely driven by the variation of growth duration.
  • Journal article
    Jia H, Quaas J, Gryspeerdt E, Bohm C, Sourdeval Oet al., 2022,

    Addressing the difficulties in quantifying droplet number response to aerosol from satellite observations

    , Atmospheric Chemistry and Physics, Vol: 22, Pages: 7353-7372, ISSN: 1680-7316

    Aerosol–cloud interaction is the most uncertain component of the overall anthropogenic forcing of the climate, in which cloud droplet number concentration (Nd) sensitivity to aerosol (S) is a key term for the overall estimation. However, satellite-based estimates of S are especially challenging, mainly due to the difficulty in disentangling aerosol effects on Nd from possible confounders. By combining multiple satellite observations and reanalysis, this study investigates the impacts of (a) updraft, (b) precipitation, (c) retrieval errors, and (d) vertical co-location between aerosol and cloud on the assessment of S in the context of marine warm (liquid) clouds. Our analysis suggests that S increases remarkably with both cloud-base height and cloud geometric thickness (proxies for vertical velocity at cloud base), consistent with stronger aerosol–cloud interactions at larger updraft velocity for midlatitude and low-latitude clouds. In turn, introducing the confounding effect of aerosol–precipitation interaction can artificially amplify S by an estimated 21 %, highlighting the necessity of removing precipitating clouds from analyses of S. It is noted that the retrieval biases in aerosol and cloud appear to underestimate S, in which cloud fraction acts as a key modulator, making it practically difficult to balance the accuracies of aerosol–cloud retrievals at aggregate scales (e.g., 1 grid). Moreover, we show that using column-integrated sulfate mass concentration (SO4C) to approximate sulfate concentration at cloud base (SO4B) can result in a degradation of correlation with Nd, along with a nearly twofold enhancement of S, mostly attributed to the inability of SO4C to capture the full spatiotemporal variability of SO4B. These findings point to several potential ways forward to practically account for the major influential factors by means of satellite observations and reanalysis, aiming at optimal observational estimates of global radia
  • Journal article
    Archer M, Cottingham M, Hartinger M, Shi X, Coyle S, Hill E, Fox M, Masongsong Eet al., 2022,

    Listening to the magnetosphere: How best to make ULF waves audible

    , Frontiers in Astronomy and Space Sciences, Vol: 9, ISSN: 2296-987X

    Observations across the heliosphere typically rely on in situ spacecraft observations producing time-series data. While often this data is analysed visually, it lends itself more naturally to our sense of sound. The simplest method of converting oscillatory data into audible sound is audification—a one-to-one mapping of data samples to audio samples—which has the benefit that no information is lost, thus is a true representation of the original data. However, audification can make some magnetospheric ULF waves observations pass by too quickly for someone to realistically be able to listen to effectively. For this reason, we detail various existing audio time scale modification techniques developed for music, applying these to ULF wave observations by spacecraft and exploring how they affect the properties of the resulting audio. Through a public dialogue we arrive at recommendations for ULF wave researchers on rendering these waves audible and discuss the scientific and educational possibilities of these new methods.
  • Journal article
    Shaylor M, Brindley H, Sellar A, 2022,

    An evaluation of two decades of aerosol optical depth retrievals from MODIS over Australia

    , Remote Sensing, Vol: 14, Pages: 1-23, ISSN: 2072-4292

    We present an evaluation of Aerosol Optical Depth (AOD) retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) over Australia covering the period 2001–2020. We focus on retrievals from the Deep Blue (DB) and Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithms, showing how these compare to one another in time and space. We further employ speciated AOD estimates from Copernicus Atmospheric Monitoring Service (CAMS) reanalyses to help diagnose aerosol types and hence sources. Considering Australia as a whole, monthly mean AODs show similar temporal behaviour, with a well-defined seasonal peak in the Austral summer. However, excepting periods of intense biomass burning activity, MAIAC values are systematically higher than their DB counterparts by, on average, 50%. Decomposing into seasonal maps, the patterns of behaviour show distinct differences, with DB showing a larger dynamic range in AOD, with markedly higher AODs (ΔAOD∼0.1) in northern and southeastern regions during Austral winter and summer. This is counter-balanced by typically smaller DB values across the Australian interior. Site level comparisons with all available level 2 AOD data from Australian Aerosol Robotic Network (AERONET) sites operational during the study period show that MAIAC tends to marginally outperform DB in terms of correlation (RMAIAC = 0.71, RDB = 0.65) and root-mean-square error (RMSEMAIAC = 0.065, RMSEDB = 0.072). To probe this behaviour further, we classify the sites according to the predominant surface type within a 25 km radius. This analysis shows that MAIAC’s advantage is retained across all surface types for R and all but one for RMSE. For this surface type (Bare, comprising just 1.2% of Australia) the performance of both algorithms is relatively poor, (RMAIAC = 0.403, RDB = 0.332).
  • Journal article
    Badman ST, Brooks DH, Poirier N, Warren HP, Petrie G, Rouillard AP, Arge CN, Bale SD, Aguero DDP, Harra L, Jones S, Kouloumvakos A, Riley P, Panasenco O, Velli M, Wallace Set al., 2022,

    Constraining Global Coronal Models with Multiple Independent Observables

    , ASTROPHYSICAL JOURNAL, Vol: 932, ISSN: 0004-637X
  • Journal article
    Ma B, Chen L, Wu D, Pulupa M, Bale SDet al., 2022,

    Discrepancy between the Low-frequency Cutoffs of Type III Radio Bursts Based on Simultaneous Observations by WIND and PSP

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 932, ISSN: 2041-8205
  • Journal article
    Bourouaine S, Perez JC, Raouafi NE, Chandran BDG, Bale SD, Velli Met al., 2022,

    Features of Magnetic Field Switchbacks in Relation to the Local-field Geometry of Large-amplitude Alfvenic Oscillations: Wind and PSP Observations

    , ASTROPHYSICAL JOURNAL LETTERS, Vol: 932, ISSN: 2041-8205
  • Journal article
    Hunt GJ, Provan G, Bradley TJ, Cowley SWH, Dougherty MK, Roussos Eet al., 2022,

    The response of Saturn's dawn field-aligned currents to magnetospheric and ring current conditions during Cassini's proximal orbits: evidence for a Region 2 response at Saturn

    , Journal of Geophysical Research: Space Physics, Vol: 127, Pages: 1-15, ISSN: 2169-9380

    Cassini's 2017 proximal orbits provided the opportunity to examine the auroral field-aligned currents in the northern hemisphere dawn sector in relation to wider magnetospheric conditions. We combine three recent studies to examine the response of the dawn region auroral field-aligned currents and the azimuthal ring currents to compressions and expansions of the Saturnian magnetosphere. For compressions of Saturn's magnetosphere resulting in tail reconnection, the currents within the downward current sheet, located equatorward of the main auroral oval, increases in strength with increasing total ring current and location of the peak downwards current moves inwards toward Saturn. While the inverse relation occurs during intervals of quiet or expanded magnetospheric conditions. During compression events there is an increase in the energetic particle intensities, in particular in the protons (35–506 keV), within the downward current region. This current system is akin to an Earth-like “region 2” field aligned current within Saturn's magnetosphere, with tail reconnection occurring when the magnetosphere is compressed resulting in a partial nightside ring current closed by a downward current near to dawn. Within the upward current sheet, mapping to Saturn's main auroral oval, both non-rotating subcorotating current and the rotating Planetary Period Oscillations (PPOs) currents flow. The upward current is strongly modulated by the PPOs but also increases in strength, with enhanced high-energy protons, during intervals of magnetospheric compressions and tail reconnection. We conclude that the enhanced plasma injected into the midnight-dawn sector during tail reconnection events results in an enhanced subcorotation current system.
  • Journal article
    Agiwal O, Masters A, Hunt G, Dougherty Met al., 2022,

    The contribution of planetary period oscillations towards circulation and mass loss in Saturn’s magnetosphere

    , Journal of Geophysical Research: Space Physics, Vol: 127, Pages: 1-17, ISSN: 2169-9380

    Magnetic reconnection is a process during which magnetic energy is released as kinetic energy. It is considered a crucial driver of energy transport and mass loss within Saturn's magnetosphere. On long-term timescales, is thought to be predominantly driven by the rapid rotation of equatorially mass-loaded flux tubes (i.e., the Vasyliunas cycle), but there is some non-negligible driving from the solar wind as well (i.e., the Dungey cycle). In this study, we investigate an atmospheric driven phenomenon that modulates Saturn's magnetosphere every ∼10.6–10.8 hr, known as planetary period oscillations (PPOs), as an additional driver of magnetic reconnection at Saturn. Using an empirical model of PPO dynamics and Cassini magnetic field and plasma measurements, we find that PPO-driven magnetic reconnection is likely to occur in Saturn's magnetosphere, however, the occurrence of the phenomenon depends on temporally variable characteristics of the PPO systems and spatial asymmetries within Saturn's equatorial magnetosphere. Thus, it is not expected to be an on-going process. On year-long timescales, we find that PPOs are expected to be on par with the Dungey Cycle in driving circulation within Saturn's magnetosphere. However, on ∼1–2 weeks-long timescales, under specific conditions where PPO-driven reconnection is expected to be active, this phenomenon can become more significant than the Vasyliunas cycle, and thus dominate circulation within Saturn's magnetosphere. On year-long timescales, this process is estimated to remove upwards of ∼20% of the mass loaded into the magnetosphere by Enceladus.
  • Journal article
    Pal S, Lynch BJ, Good SW, Palmerio E, Asvestari E, Pomoell J, Stevens ML, Kilpua EKJet al., 2022,

    Eruption and Interplanetary Evolution of a Stealthy Streamer-Blowout CME Observed by PSP at ∼0.5 AU

    , FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, Vol: 9, ISSN: 2296-987X
  • Journal article
    Gangopadhyay A, Seshadri AK, Sparks NJ, Toumi Ret al., 2022,

    The role of wind-solar hybrid plants in mitigating renewable energy-droughts

    , Renewable Energy, ISSN: 0960-1481
  • 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
    Sishtla CP, Pomoell J, Kilpua E, Good S, Daei F, Palmroth Met al., 2022,

    Flux-tube-dependent propagation of Alfven waves in the solar corona

    , ASTRONOMY & ASTROPHYSICS, Vol: 661, ISSN: 0004-6361
  • 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
  • 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
    Sishtla CP, Pomoell J, Kilpua E, Good S, Daei F, Palmroth Met al., 2022,

    Flux-tube-dependent propagation of Alfvén waves in the solar corona

    , Astronomy &amp; Astrophysics, Vol: 661, Pages: A58-A58, ISSN: 0004-6361

    <jats:p><jats:italic>Context.</jats:italic> Alfvén-wave turbulence has emerged as an important heating mechanism to accelerate the solar wind. The generation of this turbulent heating is dependent on the presence and subsequent interaction of counter-propagating Alfvén waves. This requires us to understand the propagation and evolution of Alfvén waves in the solar wind in order to develop an understanding of the relationship between turbulent heating and solar-wind parameters.</jats:p><jats:p><jats:italic>Aims.</jats:italic> We aim to study the response of the solar wind upon injecting monochromatic single-frequency Alfvén waves at the base of the corona for various magnetic flux-tube geometries.</jats:p><jats:p><jats:italic>Methods.</jats:italic> We used an ideal magnetohydrodynamic model using an adiabatic equation of state. An Alfvén pump wave was injected into the quiet solar wind by perturbing the transverse magnetic field and velocity components.</jats:p><jats:p><jats:italic>Results.</jats:italic> Alfvén waves were found to be reflected due to the development of the parametric decay instability (PDI). Further investigation revealed that the PDI was suppressed both by efficient reflections at low frequencies as well as magnetic flux-tube geometries.</jats:p>
  • 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
  • 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
    Bale SD, 2022,

    Eugene N. Parker (1927-2022)

    , SCIENCE, Vol: 376, Pages: 461-461, ISSN: 0036-8075

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