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direct imaging spectroscopy with future space-based telescopes will constrain terrestrial planet atmospheric composition and potentially detect biosignature gases. one promising indication of life is abundant atmospheric o2. however, various non-biological processes could also lead to o2 accumulation in the atmospheres... | constraining background n2 inventories on directly imaged terrestrial exoplanets to rule out o2 false positives |
the flare xuv (x rays + extreme uv) emission from m dwarf stars (0.08 ‑ 0.6 mȯ) occasionally increases the stellar xuv flux by more than two orders of magnitude above quiescent levels and can impact the habitability of planets around these stars. this wavelength range can warm and ionize the terrestrial planets' upper ... | atmospheric loss of planets around m dwarf stars due xuv radiation by flares |
coronal mass ejections (cmes) on cool stars are an interesting growing field of research especially with the growing number of detected exoplanets around this type of stars. exoplanet habitability depends on many factors including space weather due to stellar cmes that may affect exoplanetary atmospheres. it is therefo... | detection of coronal mass ejections on m stars: mystery vs reality |
the evaporation and disintegration of rocky exomoons are expected to leave significant ultraviolet, optical, infrared and/or radio signatures in the exospheres and magnetospheres of their host exoplanet. we present ongoing observations and analyses of a population of candidate exomoon systems whose sodium and potassium... | evaporative transmission spectra of rocky exomoons: dishoom and prometheus |
context. the hearts survey aims to probe the upper layers of the atmosphere by detecting resolved sodium doublet lines, a tracer of the temperature gradient, and atmospheric winds. kelt-10b, one of the targets of hearts, is a hot-inflated jupiter with 1.4 rjup and 0.7 mjup. recently, there was a report of sodium absorp... | hot exoplanet atmospheres resolved with transit spectroscopy (hearts). viii. nondetection of sodium in the atmosphere of the aligned planet kelt-10b |
lyman-alpha transits provide a window into atmospheric escape, a process that has observably shaped the exoplanet population. however, mass loss estimates from these observations are highly model dependent. a recently predicted feature of hot jupiter transits could begin dismantling this model dependence: the delayed t... | observing the overlooked double lyman-alpha transit of hd 189733 b to break mass loss rate degeneracies |
extremely low density exoplanets are tantalizing targets for atmospheric characterization, not only because of their promisingly large signals in transmission spectroscopy, but also because their atmospheres may help us understand their large radii. we present the first analysis of the atmosphere of the lowest-density ... | metals and a potential extended outflow in the atmosphere of hat-p-67b, the puffiest gas giant |
in this work, the kinetic model of aeronomy of the upper atmosphere of an exoplanet is extended by including the effect of stellar wind plasma on the extended hydrogen corona of a hot sub-neptune. for this purpose, the precipitation of high-energy protons and hydrogen atoms into planetary atmospheres was studied using ... | kinetic model of the effect of the stellar wind on the extended hydrogen atmosphere of the exoplanet π men c |
two planets have been detected around the 23 myr pre-main sequence m dwarf au mic; their known age makes them good probes for early stages of exoplanet evolution. au mic c is the 2.56 earth radius outer planet orbiting with a period of 18.9 days. it has a mass of about 20 earth masses. the planet's relatively low densi... | the evaporating atmosphere of a planet in the young bright multiplanet system au mic |
jeans escape or hydrodynamic escape is believed to dominate atmospheric loss for hot jupiters. however, nonthermal mechanisms likely contribute substantially on hydrogen-rich "super-earths" with relatively cold and extended atmospheres. this study is devoted to investigating the role of stellar wind sputtering on keple... | nonthermal atmospheric escape on the kepler-11 "super-earths" driven by stellar wind sputtering |
one of the most intriguing outcomes of the young field of exoplanet research is the emergence of highly-irradiated planets, located much closer to their host star than any of the solar system planets. these planets, which give us a glimpse into the future of our solar system once the sun reaches its final life stages, ... | hotter than hell: understanding highly-irradiated worlds through transmission spectroscopy |
water-rich planets should be ubiquitous in the universe, and could represent a notable fraction of the sub-neptune population. among the detected exoplanets that have been characterized as sub-neptunes, many are subject to important irradiation from their host star. as a consequence, hydrospheres of such planets are no... | interior structure and possible existence of irradiated ocean planets |
one of the top recommendations of the astro2020 decadal was a future large flagship mission spanning the far uv to near ir. although primarily designed to enable direct imaging of potentially habitable exoplanets and general astrophysics, such a flagship will also have revolutionary capabilities to build on the legacy ... | exoplanet transit spectroscopy with a future large uv to ir flagship observatory |
hot jupiters represent a class of exoplanet orbiting very close to their parent star and are expected to exhibit large mass escape rates (up to ~1010 - 1011 g/s) due to the intense stellar euv/uv heating. we examine the differences between mass escape rates predicted by both a one-dimensional (1-d) and a three-dimensio... | exodus from osiris: quantifying the mass escape from hd 209458 b. |
observed high multiplicity planetary systems are often tightly packed. numerical studies indicate that such systems are susceptible to dynamical instabilities. dynamical instabilities in close-in tightly packed systems, similar to those found in abundance by kepler, often lead to planet-planet collisions. for sub-neptu... | outcomes of sub-neptune collisions |
planet formation models suggest that the small exoplanets that migrate from beyond the snowline of the protoplanetary disk likely contain water-ice-rich cores ($\sim 50\%$ by mass), also known as the water worlds. while the observed radius valley of the kepler planets is well explained with the atmospheric dichotomy of... | where are the water worlds? identifying the exo-water-worlds using models of planet formation and atmospheric evolution |
the intense stellar energy input into exoplanets on short orbits can lead to a dramatic expansion of their upper atmosphere, and its escape into space. recently, spectrally-resolved uv transits of the warm neptune gj436b with the hubble space telescope revealed a giant tail of hydrogen surrounding the planet. this disc... | warm neptunes : a sweet spot for atmospheric characterization |
the escape of the atmosphere plays a crucial role in planetary evolution. recent advancements in high spectral resolution transmission spectrum observation have provided an exceptional opportunity to investigate the structure of exoplanet upper atmospheres and their escape processes. in this talk, i will introduce a so... | a hydrodynamic study of the atmospheric escape of the hot jupiter wasp-121b |
machine learning, and eventually true artificial intelligence techniques, are extremely important advancements in astrophysics and astronomy. we explore the application of deep learning using neural networks in order to automate the detection of astronomical bodies for future exploration missions, such as missions to s... | model optimization for deep space exploration via simulators and deep learning |
solar radiation management (or geoengineering) can be used to deliberately alter the earth's radiation budget, by reflecting sunlight to space. this has been suggested as a response to anthropogenic global warming, to partly or fully balance radiative forcing [1]. approximately 22% of sun-like stars have earth-like exo... | technical note: geoengineering on exoplanets |
jwst is poised to detect and characterize terrestrial exoplanet atmospheres in the search for biosignatures (morley et al., 2017, lustig-yaeger et al., 2019), but the correct interpretation of those observations is predicated on understanding the system's long-term evolution. a well-known example, trappist-1, harbors 7... | constraining the water loss histories of the trappist-1 exoplanets |
thanks for the wide-field exoplanet surveys on the ground and in the space, thousands of exoplanet samples have been found in the last two decades. from dome a, the highest point of the antarctic plateau, we have also contributed over 100 candidates using the ast3 telescopes in 2018. now, besides searching, we are prog... | exoplanets in the antarctic sky: from searching to characterizing |
there is currently a gap in our understanding of wide-orbit planets, which must be filled if we are to understand planet formation and exoplanet habitability. we summarize current and planned exoplanet detection programs using a variety of methods: microlensing (including wfirst), radial velocities, gaia astrometry, an... | wide-orbit exoplanet demographics |
solar radiation management (srm) geoengineering can be used to deliberately alter the earth's radiation budget, by reflecting sunlight to space. srm has been suggested as a response to anthropogenic global warming (agw), to partly or fully balance radiative forcing from agw [1]. approximately 22% of sun-like stars have... | geoengineering on exoplanets |
i will discuss how stellar variability affects the detection of exoplanets via the transit and radial velocity methods, and the characterisation of their atmospheres. i will review the increasingly sophisticated methods developed in the last few years to minimise this impact, and outline how stellar variability is like... | the impact of stellar variability on the detectability of exoplanets |
the existence of worlds beyond our own has been a subject of fascination and inspiration since the times of the ancient greeks. the first exoplanet discovery in wolszczan and frail 1992 led to a revolution that sparked the scientific community to develop new space missions (e.g. kepler, tess and ariel) and instruments ... | elementary students as transpersonal researchers: guided cognitive imagery on science test scores using a mixed-methods approach |
exoplanet detection opens the door to the discovery of new habitable worlds and helps us understand how planets were formed. with the objective of finding earth-like habitable planets, nasa launched kepler space telescope and its follow up mission k2. the advancement of observation capabilities has increased the range ... | exosgan and exoacgan: exoplanet detection using adversarial training algorithms |
the next generation of giant ground and space telescopes will have the light-collecting power to detect and characterize potentially habitable terrestrial exoplanets using high-contrast imaging for the first time. this will only be achievable if the performance of giant segmented mirror telescopes (gsmts) extreme adapt... | three-sided pyramid wavefront sensor. ii. preliminary demonstration on the new cacti testbed |
the astro2020 report outlines numerous recommendations that could significantly advance technosignature science. technosignatures refer to any observable manifestations of extraterrestrial technology, and the search for technosignatures is part of the continuum of the astrobiological search for biosignatures. the searc... | opportunities for technosignature science in the astro2020 report |
the development of spaceborne coronagraphic technology is of paramount importance to the detection of habitable exoplanets in visible light. in space, coronagraphs are able to bypass the limitations imposed by the atmosphere to reach deeper contrasts and detect faint companions close to their host star. to effectively ... | the space coronagraph optical bench (scoob): 1. design and assembly of a vacuum-compatible coronagraph testbed for spaceborne high-contrast imaging technology |
we are at a unique timeline in the history of human evolution where we may be able to discover earth-like planets around stars outside our solar system where conditions can support life or even find evidence of life on those planets. with the launch of several satellites in recent years by nasa, esa, and other major sp... | automation of transiting exoplanet detection, identification and habitability assessment using machine learning approaches |
the detection of exoplanets in the past three decades has revealed the fact that planets are ubiquitous in the universe. in order to deeply study the ubiquity of habitable planets, on one hand, we need to understand the characteristics of habitable planets; on the other hand, we can analyze the the distribution charact... | estimations of planetary occurrence rates for solar-type stars with data release 25 from kepler q1-q17 observations |
the detection and characterization of earth-like exoplanets around sun-like stars is a primary science motivation for the habitable worlds observatory. however, the current best technology is not yet advanced enough to reach the 10−10 contrasts at close angular separations and at the same time remain insensitive to low... | integrated photonic-based coronagraphic systems for future space telescopes |
the 2020 decadal survey on astronomy and astrophysics endorsed space-based high contrast imaging for the detection and characterization of habitable exoplanets as a key priority for the upcoming decade. to advance the maturity of starlight suppression techniques in a space-like environment, we are developing the space ... | the space coronagraph optical bench (scoob): 2. wavefront sensing and control in a vacuum-compatible coronagraph testbed for spaceborne high-contrast imaging technology |
coronal mass ejections (cmes) normally refer to large-scale plasma clouds ejected from the sun. on other stars, similar phenomena are called stellar coronal mass ejections or stellar cmes. based on our current understanding of solar cmes, it is believed that stellar cmes are likely the main drivers of space weather in ... | observations and simulations of stellar coronal mass ejections |
in a few years, space telescopes will investigate our galaxy to detect evidence of life, mainly by observing rocky planets. in the last decade, the observation of exoplanet atmospheres and the theoretical works on biosignature gasses have experienced a considerable acceleration. the~most attractive feature of the realm... | super-earths, m dwarfs, and photosynthetic organisms: habitability in the lab |
we use gps networks to measure the vertical total electron content (vtec) variations at low latitude, in three longitude sectors: america, europe-africa and asia, collected during the period 2013-2017. this period corresponds to the increasing phase of the solar cycle 24 (sc#24) observed around 2013-2014 as well as the... | transient variations of vertical total electron content at low latitude during the period 2013-2017 |
keywords: equatorial and low-latitude ionosphere, global navigation satellite systems (gnss), nequick 2 model, total electron content. satellite communication systems such as global navigation satellite systems (gnss) and other related radio systems in the brazilian sector are strongly affected by the effects of solar ... | latitudinal variation of the vertical total electron content (vtec) over the brazilian longitudinal sector during distinct phases of the solar cycle 24: observations and nequick 2 model assessment. |
using high-resolution (5 min) solar wind data and westward auroral electrojet index (al) index since 1981, temporal variation of the sun-earth coupling efficiency (al response to the solar wind electromagnetic energy/flux input) was examined. to separate the seasonal variation, 3-month averaged statistics is used. (1) ... | singular year of high geomagnetic responses to the same solar wind input |
we present analysis of the complete spectral dataset from the extreme-ultraviolet (euv) variability experiment (eve) megs-a instrument. using these data, we construct daily differential emission measures (dems) and use them to analyze the long-term variability of the global corona and the irradiance it produces. we ide... | the slowly varying corona: findings from dems with the eve megs-a dataset |
the problem of the transport and transformation of magnetic fields from the generation zone to the photosphere is studied in this paper. for this purpose, the temporal variations of parameters of bipolar magnetic regions are analyzed based on the magnetic synoptic maps of the wilcox solar observatory (wso) for the decl... | temporal variations of the magnetic flux in the solar photosphere |
we present principal components analysis (pca) of temporal magnetic field variations over the solar cycles 21-24 and their classification with symbolic regression analysis using hamiltonian method. pca reveals 4 pairs of magnetic waves with a significant variance and the two principal components with the highest eigen ... | two principal components of solar magnetic field variations and prediction of solar activity on multi-millennium timescale |
the helioseismic and magnetic imager (hmi) on nasa’s solar dynamics observatory (sdo) has continuously measured the vector magnetic field, intensity, and doppler velocity in solar flares and over the entire solar disk since may 2010. the regular cadence of 45 seconds for line-of-sight and 12 minutes for vector measurem... | hmi observations of solar flares in cycle 24 |
the long-lasting minimum of solar cycle 23 as well as the overall weak maximum of cycle 24 reveal the possibility for a return to grand solar minimum conditions within the next decades. the past 1,000 years featured at least 5 excursions (lasting 60-100 years) of exceptionally low solar activity, induced by a weak magn... | effect of the chosen solar irradiance dataset on simulations of a future grand minimum: results from a state-of-the-art chemistry-climate model |
an actual problem today is the search for observed evidence of the existence of deep small-scale magnetic fields of the sun. in this regard, the authors analyzed the theoretical criterion for separating the contributions to the solar surface magnetism of two qualitatively different mechanisms of a small-scale dynamo, t... | theoretical and observed signs of excitation of small-scale magnetic fluctuations in the depth of the sun |
the methods of ionospheric radio tomography (rt) are actively developing at present. these methods are suitable for reconstructing the spatial distributions of electron density from radio signals transmitted from the navigational satellite systems and recorded by the networks of ground-based receivers. the rt systems b... | application of high- and low-orbiting radio tomography for exploring the ionospheric structures on different scales |
analysis of helioseismology data obtained in 1996-2019 for two solar cycles from two space missions, solar and heliospheric observatory (soho) and solar dynamics observatory (sdo), reveals that latitudinal variations of solar rotation ('torsional oscillations') are associated with hydromagnetic dynamo waves initiated i... | detection of dynamo waves in the solar convection zone by helioseismology |
recently discovered long-term oscillations of the solar background magnetic field associated with double dynamo waves generated in inner and outer layers of the sun indicate that the solar activity is heading in the next three decades (2019-2055) to a modern grand minimum similar to maunder one. on the other hand, a re... | retracted article: oscillations of the baseline of solar magnetic field and solar irradiance on a millennial timescale |
we have concluded that in the powerful magnetosphere of jupiter, the sunflower point, changing over the orbital period by an angle of >26°, causes variations in physical characteristics of the atmosphere, manifesting seasonal changes. a significant eccentricity of the planetary orbit leads to the fact that the influ... | seasonal changes of activity factor for jupiter's hemispheres restored its periodicity |
different boundaries could be defined in a planetary ionosphere where the dominant process in function switches from one to the other. identifying these boundaries and understanding their variations are hence crucial for disentangling the complexity of the ionosphere. focusing on mars, we perform a data-driven analysis... | characteristic timescales for the dayside martian ionosphere: chemistry, diffusion, and magnetization |
recent observations and analyses strongly indicate that the strength of the sun's polar fields at the end of a cycle predicts the strength of the next solar cycle. the surface magnetic flux transport that builds up these polar fields is now well observed and is realistically modeled with the advective flux transport (a... | solar cycle prediction with the advective flux transport (aft) code |
climate is the statistical distribution of observed weather and we thus expect the climate of space weather to vary with the solar cycle of activity. the 11-year solar cycle is irregular, with each cycle exhibiting a unique duration and peak activity. the distinct activity of each cycle is then coupled from the sun to ... | solar cycle dependence of the distribution of solar wind in-situ plasma parameters, and how this drives solar wind-magnetosphere coupling parameters. |
the long-term millennial oscillations of the baseline solar background magnetic field (sbmf) and the ephemeris of the sun-earth distances are compared with the oscillations of solar irradiance at the terrestrial biomass (hallstatt's cycle). based the sun-earth distances derived from the current jpl ephemeris based on s... | solar total radiation input and terrestrial temperature in the two millennia of 600-2600 |
quasi-biennial oscillations (qbo) are the most pronounced midterm periodicity lower than schwabe cycle and greater than the solar rotation rate. it has been noticed in sunspot number and area, the number of hα flares, solar radio flux, coronal green line intensity, photospheric magnetic field, solar wind speed, heliosp... | how sun produces quasi-biennial oscillations of cosmic rays? |
cyclical variations of the solar magnetic fields, and hence the level of solar activity, is among the top interests of space weather research and relates to climate change on earth. surface flows in global-scale, in particular differential rotation and meridional flows, play important roles in the solar dynamo that des... | study of global photospheric and chromospheric flows over multiple solar cycles |
this study presents robust and quantitative analyses of 4 supersubstorms from the solar cycle 24 identified by the super magnetic lower (sml) index <-2500 nt. these events have been associated with moderate geomagnetic storms. the energy input and total energy dissipation in all these cases have been found to be a f... | a synthetic analysis of the supersubstorms of solar cycle 24: the sources, s-m-i coupling and impacts |
potential deleterious health effects to astronauts induced by space radiation is one of the most important long-term risks for human space missions, especially future planetary missions to mars which require a return-trip duration of about 3 years with current propulsion technology. in preparation for future human expl... | the state-of-the-art evaluation of the mars radiation environment |
this paper analyzes geomagnetic disturbances associated with seismic events in the northern transcurrent margin of the south sandwich microplate and south american plate, with their epicenter at distances within 350 km from king edward point geomagnetic observatory on the archipelago of the georgias del sur islands. ge... | wavelet-based characterization of seismicity and geomagnetic disturbances in the south sandwich microplate area |
at high magnetic latitudes, ions move up and down through the topside ionosphere and significantly affect the structure and dynamics of the thermosphere-ionosphere-magnetosphere system. the vertical ion drift velocities (vz) of dmsp f11, f12, f14, f15, and f16 are rescaled by taking f13 data as the reference. through r... | hemispheric asymmetry of the vertical ion drifts observed by dmsp |
in this paper, we present the results of a study of cyclic variations in magnetic fields of various scales in cycles 21-25: large-scale magnetic fields reflecting the dynamics of the global magnetic field of the sun, the number of spots, which characterizes the dynamics of local magnetic fields of spots, and the intens... | the relationships between cyclic variations of solar magnetic fields of various scales in cycles 21-25 |
a. m. benedito nunes (co-first author), j. gamper (co-first author), m. friel, j. w. gjerloev, s.c. chapman the newcomb-benford law (nbl) prescribes the probability distribution of the first digit of variables under conditions including aggregation. it will not apply where there is strong truncation or a cut-off. we ap... | newcomb-benford law characterization of solar wind magnetic field and geomagnetic indices |
geomagnetically induced currents (gic) constitute an integral part of space weather research and are a subject of ever-growing attention for countries located in the low and middle latitudes. a series of recent studies highlights the importance of considering gic risks for the mediterranean region. here, we exploit dat... | investigation of the geomagnetically induced current index levels in the mediterranean region during the strongest magnetic storms of solar cycle 24 |
electromagnetic radial diffusion is one of the main mechanisms for radiation belt acceleration. yet, quantifying radial diffusion remains a major challenge. the goal of this work is to compare and contrast different ways to quantify electromagnetic radial diffusion, to improve its specification and to contribute to cur... | investigating differences in electromagnetic radial diffusion estimates |
energetic neutral atoms (enas) are an important tool for investigating the structure of the heliosphere. observations within an energy band from ~1 to ~90 kev show a structured, energy-dependent globally distributed flux and two arc-like strips of enhanced emission, with the location and width depending on the energy. ... | a unified interpretation of ena observations from cassini, ibex, and soho |
departures from spherical symmetry split the frequencies of the sun's normal oscillation modes. in addition to the well-studied, dominant splitting of the mode frequencies, due to the first-order advection of internal wave motion, a number of second-order effects of rotation on the frequency splittings, predominantly t... | possible signature of solar oblateness in the sun's oscillation frequency splittings |
based on ionospheric total electron content (tec) data for zhongshan station (zhs) and scott base station (sba) in antarctica, acquired during 2010-2020, high-latitude ionospheric tec diurnal variations of two near cusp latitude stations were studied. the magnetic latitude and longitude differences between the two stat... | a comparative study of ionospheric tec diurnal variations at two stations near cusp latitudes in the southern hemisphere |
various measures of solar activity show that the minima preceding cycles 24 and 25 were deeper and wider than several earlier minima. these provide a unique opportunity for studying the sun's properties that are otherwise altered in the presence of strong fields. the solar magnetic field is generated in the interior an... | what deep and extended minima tell us about magnetism below the surface? |
spatio-temporal variations of ionospheric currents cause rapid magnetic field variations at ground level and geomagnetically induced currents (gics) that can be harmful for human infrastructure. the risk for large excursions in the magnetic field time derivative, "db/dt spikes", is known to be high during geomagnetic s... | space weather disturbances in non-stormy times: occurrence of db/dt spikes during three solar cycles |
the solar wind is an uninterrupted flow of highly ionised plasma that streams from compact sources at or near the sun, accelerates across the low solar corona, and expands into the whole interplanetary space. the physical properties of any wind streams thus reflect the characteristics of their source regions and those ... | steady and transient solar wind sources, acceleration profiles and rotation across the solar activity cycle |
we review here the occurrence of magnetic storms during the space age (1957 - 2021), as observed by two storm indices, the dst index and the dxt index. we study the solar sources of storms, describe the dramatic changes in the different types of storms during the space age, and explain these changes in terms of the lon... | magnetic storms during the space age: occurrence and relation to varying solar activity |
observations of auroras in russia from 1837 to 1900 have been catalogued on the basis of data of the russian network of meteorological observatories. these observation data from 129 stations in the european and asian parts of russia cover a wide geographical zone (ϕ = 39°57'-72°30' n and λ = 21°1'-224°35' e). a differe... | variations in the occurrence frequency of aurora in 1837-1900 from data of the russian network of meteorological observatories |
a magnetosphere is an isolated sphere dropped inside the solar wind where it is in equilibrium. when a solar wind structure impacts the magnetosphere, then, the equilibrium is broken and the whole magnetospheric reacts to prevent a magnetospheric collapse. the cirs are one of the main solar wind structures. they are no... | a cir impact study on the radiation belts fluxes |
geomagnetically induced currents (gic) constitute an integral part of space weather research and are a subject of ever-growing attention for countries located in the low and middle latitudes. a series of recent studies highlights the importance of considering gic risks for the mediterranean region. here, we exploit dat... | investigating the levels of geomagnetically induced currents in the mediterranean region during the most intense geomagnetic storms of solar cycle 24 |
the paper summarizes the issues related to relationships between the pc index and magnetic disturbances: threshold level of the pc index required for the disturbances beginning, delay time in response of magnetic substorms and storms to the pc index growth, relation of pc index to magnetospheric field-aligned currents ... | pc index as a ground-based indicator of the solar wind energy incoming into the magnetosphere: (2) relation of pc index to magnetic disturbances |
seps are correlated with the 11-year solar cycle due to their production by flares and interaction with the inner heliosphere, while gcrs are anti-correlated with it due to the modulation of the heliospheric magnetic field. the solar magnetic field along the cycle varies in amplitude but also in geometry, causing diffu... | energetic particles and the solar cycle: impact of solar magnetic field amplitude and geometry on seps and gcrs diffusion coefficients |
this paper analyzes the latitudinal and temporal variations of magnetic fields in the photosphere and variations of solar structures, such as active regions, coronal holes, and flocculi, in the sun's upper chromosphere. the investigation is based on two types of solar observations obtained in the kitt peak observatory ... | features of the evolution of active and quiet structures in two levels of the sun's atmosphere |
interplanetary magnetic field (imf) carried by solar wind and rooted at solar corona. variations of imf depend on solar surface activities, e.g. sunspots. moreover, solar magnetic storms are connected by the imf. imf parameters, sunspot number, and geomagnetic index for more than 55 years were downloaded from omniweb, ... | variations of imf cone angle and imf clock angle to solar cycles and geomagnetic storms |
because the solar magnetic activity cycle modulates the sun's radiative output and solar wind properties, as well as the frequency of all geoeffective solar eruptive phenomena, predicting its characteristics --amplitude, duration, timing of maxima and polarity reversals-- remains a cornerstone of space weather research... | can the solar cycle be predicted ? |
total solar irradiance (tsi) is the earth's primary energy input and is a fundamental ingredient for the understanding and characterization of a large variety of phenomena which include the modeling of terrestrial global or regional climate. reliable measurements of the tsi have only existed from the late 70s, as they ... | total solar irradiance during the last five centuries and the maunder minimum |
coronal holes often sit in sun's polar regions, and they are believed to be responsible for the fast solar wind. the magnetic field therein is open to the heliosphere. it is possible that such field may emanate from small patches with enhanced field strength, which were first revealed in data from the spectropolarimete... | polar magnetic field in solar cycle 24 |
in this study, we have used international reference ionosphere (iri) maximum plasma density of f2 layer (nmf2) to gain a qualitative insight into the physical processes that accounts for the equatorial ionization anomaly (eia) intensity parameters vary with season, phase of the solar activity cycle and magnetic activit... | seasonal/solar activity dependence of equatorial ionization anomaly parameters |
we discuss the evolution of the solar corona as seen at eclipses through the solar-activity cycle. in particular, we discuss the variations of the overall shape of the corona through the relative proportions of coronal streamers at equatorial and other latitudes vs. polar plumes. we analyze the two coronal mass ejectio... | the solar corona through the sunspot cycle: preparing for the august 21, 2017, total solar eclipse |
as the sun converts hydrogen into helium by nuclear fusion there is a decrease in the sun's mass, m and the release of energy through electromagnetic and particle radiation. the continued, steady loss of mass from the sun results in a reduced gravitational attraction and an expansion of the orbits of the planets. these... | the change in the mass of the sun and the expansion of the solar system |
coronal mass ejections (cmes) and high-speed solar wind streams (hsss) are the most important large-scale solar wind structures driving geomagnetic activity. it is well known that cmes cause the strongest geomagnetic storms, while hsss drive mainly moderate or small storms. here we study the spatial-temporal distributi... | relative contributions of coronal mass ejections and high-speed streams to the long-term variation of annual geomagnetic activity: solar cycle variation and latitudinal differences |
one may use the longitudinal coverage of different spacecraft assets, or the same asset over sequential carrington rotations, to study the solar wind behavior from long-lived structures (coronal holes, active regions), or occasionally observe the extent of transient structures (farrugia et al., 2011). this is of intere... | comparing temporally-separated solar wind structures at 1 au (stereo a and omni) |
we report our 3rd year 2019lws-fst team activity, namely on (a) active regions' flows and their influence in modifying global flows, (b) long-term observations, and simulation of global flows, and (c) their influence in governing polar fields and active regions' distributions at the surface. several milestones are achi... | observations and simulations of solar flows and their roles in magnetic activity patterns at the surface |
both geosynchronous and ground-based measurements may depend on magnetic local time. such simultaneous diurnal variations can result in high, spurious correlations even when there is no physical relationship between factors. this has implications for accurate modelling using regression and for feature selection. a diff... | the use of differencing to remove spurious correlations in models of geostationary 2 mev electron flux |
the angular width of a coronal mass ejection (cme) is an important factor to determine whether the corresponding interplanetary cme (icme) and its preceding shock will reach our earth. however, very few studies are involved to study the decisive factors of the cme's angular width. in this study, we use the three-dimens... | the three-dimensional angular widths of cmes and their relations to the source regions |
the solar oscillation frequencies have shown variation over the solar activity cycle, which is believed to be the indicator of the structural and magnetic changes taking place in the sun. the ground-based network of six identical solar telescopes in the global oscillation network group (gong) program has been nearly-co... | solar-cycle variation in the photospheric mean velocity flows: gong observations |
we present a new model of thermosphere winds in the f region ionosphere obtained from variations in the altitude of the peak electron density (hmf2). the new magnetic meridional neutral thermospheric (mentat) wind model produces magnetic-meridional neutral winds as a function of year, day of year, solar local time, sol... | mentat: a new magnetic meridional neutral wind model for earth's thermosphere |
besides the well-known 11-year cycle, longer and shorter characteristic periods can be isolated in variations of the parameters of helio-geophysical activity. in geomagnetic variations, one can also isolate oscillations with characteristic periods of 5-6 years (qso) and 2-3 years (qbo). periods of ~36 and ~60 years wer... | medium-term oscillations of the solar activity |
reliable sunspot records are available for 24 solar cycles. these records show that almost no behavior of the sunspot cycle precisely repeats. rise times, declining times, peak activities all vary, nor do the two hemispheres closely follow each other. by comparing the sunspot number time series against a fixed clock wi... | what we can learn about future solar activity from existing solar records: long-term forecasts may be possible |
we study the geo-effectiveness of high-speed streams (hss) detected during the consecutive eight years (2009 - 2016) period of solar cycle 24. these hss are of different speeds and durations. during their passage, solar wind plasma and magnetic field parameters are also not similar. we utilize solar wind plasma and mag... | study of the evolution of the geomagnetic disturbances during the passage of high-speed streams from coronal holes in solar cycle 2009-2016 |
the field of space weather has made great strides in understanding and simulating large-scale, global responses of the earth's upper atmosphere to various inputs from the sun; however, the meso-scale phenomena (~30-500 km wide) that are much more dynamic and powerful in the coupled system have thus far remained unchara... | statistical properties of meso-scale plasma flows in the nightside high-latitude ionosphere |
the long-term behaviour of the solar wind and its impact on the earth are of paramount importance to understand the framework of the strong transient perturbations (cmes, sirs). solar variability related to its magnetic activity can be quantified by using synthetic indices (e.g. sunspots number) or physical ones (e.g. ... | long-term correlations in solar proxies and solar wind parameters |
in this study we investigate the variations of the hourly observations at the ionospheric observatory of rome (41.82° n, 12.51° e) during the last minimum of solar activity. the values of the critical frequency of the f2 layer (fof2) manually scaled from the ionograms recorded by the ais-ingv ionosonde, and the vertica... | study of the fof2 and vtec variations at the ionospheric observatory of rome during the last solar minimum, in relation to the geomagnetic activity |
its critical to have an accurate solar wind background in the inner heliosphere for space weather prediction, from the arrival of corotating interaction regions (cirs), to the coronal mass ejections (cmes), and solar energetic particles (seps). in the space weather community, there are two major approaches to predict t... | predicting the optimal poynting flux for different solar activity conditions for realtime solar wind prediction |
based on 9 years of quasi-continuous data observed at extremely low-frequency electromagnetic stations, the long-term variations of schumann resonances (srs) are compared and analyzed. we obtained two major parameters, namely the peak intensity and peak frequencies by lorentz fitting and focus on their seasonal and int... | seasonal and interannual variations in the schumann resonance observed in the elf electromagnetic networks in china |
we study the influence of interplanetary (ip) shock impact angles in the shock geoeffectiveness focusing on simulations and observations. in our simulations, we use openggcm simulations to study the magnetospheric and ionospheric responses to shock impacts. three cases are presented here: two inclined shocks, with 3.7 ... | geomagnetic avtivity triggered by interplanetary shocks: the shock impact angle as a controlling factor |
principal component analysis (pca) was performed on the full disk synoptic maps of solar background magnetic field (sbmf) captured from the wilcox solar observatory for 30 latitudinal bands for cycles 21-24 allowing to obtain principal components (pcs), or eigen vectors of solar magnetic field. the addition of extra-cy... | grand minimum of solar magnetic field and its links with the solar and terrestrial activity features |
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