Observations Of Aurora Research Articles

Multi-wavelength and multi-scale aurora observations at the Chinese Zhongshan Station in Antarctica

The Chinese Antarctic Zhongshan Station (ZHS) is located in a unique geographical and geomagnetic site that is suitable for observations on the cusp and of the post-noon dayside aurora and the poleward boundary of the nightside auroral oval. Since 2010, a unique, advanced synthetically auroral observation system has been deployed at ZHS, composed of a multi-wavelength all-sky imager, a multi-scale imager, a spectrum imager, and a radio imager. This system can record auroral forms from large (∼100 km) to small scales (∼10 m), auroral spectral lines from 400 to 730 nm, and auroral characteristics in the radio spectrum. Using this system, we have investigated the visible characteristics of UV ‘bright spots,’ the variation characteristics of the dayside shock auroras and convection, and the methodology for the quiet-day curve (QDC), among others. These investigations have enhanced our understanding of the solar wind–magnetosphere–ionosphere coupling process.

Observations of substorm auroras by MAIN cameras system in Apatity during two winter seasons: 2014/2015 and 2015/2016

Data of the MAIN cameras (Multiscale Aurora Imaging Network) obtained at Apatity (Kola Peninsula, Russia) during two winter seasons (2014/2015 and 2015/2016) have been used to study the substorms during different solar wind conditions. Solar wind parameters were taken from the 1-min sampled OMNI data base (http://cdaweb.gsfc.nasa.gov/cdaweb/istp_public/). Auroral disturbances were verified by the data of IMAGE magnetometers and by data of the all-sky camera at Apatity. All substorms were divided into different groups depending on the geomagnetic activity. First, the substorms were separated into two groups: substorms observed during storms and substorms under non-storm conditions. The substorms during storms were divided in sub-groups according to observations during different phases of the storm: initial, main and recovery phases, and the recovery phase was divided in near and late recovery phase. We considered also substorms during “structured recovery phase”, when the SYM/H index behavior was highly irregular. The substorms during non-storm conditions were classified as substorms under quiet conditions, when no structures in the solar wind were observed, and as substorms occurred when structures in the solar wind near the Earth were detected, but these structures did not provoke geomagnetic storms. It was shown that the latitude of the substorm onset was controlled by the value of the SYM/H index. Substorms at higher values of SYM/H index occurred to the North from the station zenith, and at smaller SYM/H values – to the South from it. The boundary between both types of substorms in terms of SYM/H index is in the range from ∼ −30 to ∼ −55 nT. It was found out also that the maximal relative intensity of auroras was greater for substorms with onset to the South from Apatity and smaller - for substorms with onset in zenith or to the North from Apatity.

Juno-UVS approach observations of Jupiter's auroras.

Juno ultraviolet spectrograph (UVS) observations of Jupiter's aurora obtained during approach are presented. Prior to the bow shock crossing on 24 June 2016, the Juno approach provided a rare opportunity to correlate local solar wind conditions with Jovian auroral emissions. Some of Jupiter's auroral emissions are expected to be controlled or modified by local solar wind conditions. Here we compare synoptic Juno‐UVS observations of Jupiter's auroral emissions, acquired during 3–29 June 2016, with in situ solar wind observations, and related Jupiter observations from Earth. Four large auroral brightening events are evident in the synoptic data, in which the total emitted auroral power increases by a factor of 3–4 for a few hours. Only one of these brightening events correlates well with large transient increases in solar wind ram pressure. The brightening events which are not associated with the solar wind generally have a risetime of ~2 h and a decay time of ~5 h.

Records of sunspots and aurora candidates in the Chinese official histories of the Yuán and Míng dynasties during 1261–1644

Abstract Records of observations of sunspots and auroras in pre-telescopic historical documents provide useful information about past solar activity both in long-term trends and short-term space weather events. In this study, we present the results of a comprehensive survey of the records of sunspots and aurora candidates in the Yuánshĭ and Míngshĭ, Chinese Official Histories spanning 1261–1368 and 1368–1644, based on continuous observations with well-formatted reportds conducted by contemporary professional astronomers. We then provide a brief comparison of these data with Total Solar Irradiance (TSI) as an indicator of the solar activity during the corresponding periods to show significant active phases between the 1350s–80s and 1610s–30s. We then compared the former with contemporary Russian reports concerning naked-eye sunspots and the latter with contemporary sunspot drawings based on Western telescopic observations. Especially some of the latter are consistent with nitrate signals preserved in ice cores. These results show us some insights on and beyond minima and maxima of solar activity during the 13th–17th centuries.

Infrared observations of Jovian aurora from Juno's first orbits: Main oval and satellite footprints

AbstractThe Jovian Infrared Auroral Mapper (JIRAM) is an imager/spectrometer on board NASA/Juno mission for the study of the Jovian aurorae. The first results of JIRAM's imager channel observations of the H3+ infrared emission, collected around the first Juno perijove, provide excellent spatial and temporal distribution of the Jovian aurorae, and show the morphology of the main ovals, the polar regions, and the footprints of Io, Europa and Ganymede. The extended Io “tail” persists for ~3 h after the passage of the satellite flux tube. Multi‐arc structures of varied spatial extent appear in both main auroral ovals. Inside the main ovals, intense, localized emissions are observed. In the southern aurora, an evident circular region of strong depletion of H3+ emissions is partially surrounded by an intense emission arc. The southern aurora is brighter than the north one in these observations. Similar, probably conjugate emission patterns are distinguishable in both polar regions.

Transient brightening of Jupiter's aurora observed by the Hisaki satellite and Hubble Space Telescope during approach phase of the Juno spacecraft

AbstractIn early 2014, continuous monitoring with the Hisaki satellite discovered transient auroral emission at Jupiter during a period when the solar wind was relatively quiet for a few days. Simultaneous imaging made by the Hubble Space Telescope (HST) suggested that the transient aurora is associated with a global magnetospheric disturbance that spans from the inner to outer magnetosphere. However, the temporal and spatial evolutions of the magnetospheric disturbance were not resolved because of the lack of continuous monitoring of the transient aurora simultaneously with the imaging. Here we report the coordinated observation of the aurora and plasma torus made by Hisaki and HST during the approach phase of the Juno spacecraft in mid‐2016. On day 142, Hisaki detected a transient aurora with a maximum total H2 emission power of ~8.5 TW. The simultaneous HST imaging was indicative of a large “dawn storm,” which is associated with tail reconnection, at the onset of the transient aurora. The outer emission, which is associated with hot plasma injection in the inner magnetosphere, followed the dawn storm within less than two Jupiter rotations. The monitoring of the torus with Hisaki indicated that the hot plasma population increased in the torus during the transient aurora. These results imply that the magnetospheric disturbance is initiated via the tail reconnection and rapidly expands toward the inner magnetosphere, followed by the hot plasma injection reaching the plasma torus. This corresponds to the radially inward transport of the plasma and/or energy from the outer to the inner magnetosphere.

Records of sunspot and aurora activity during 581–959 CE in Chinese official histories concerning the periods of Suí, Táng, and the Five Dynasties and Ten Kingdoms

Abstract Recent studies concerning radioisotopes in tree rings or ice cores suggest that extreme space weather events occurred during the pre-telescope age. Observational records of naked-eye sunspots and low-latitude auroras in historical documents during this age can provide useful information about past solar activity. In this paper, we present the results of a comprehensive survey of records of sunspots and auroras in Chinese official histories from the 6th century to the 10th century, in the period of Suí, Táng, the Five Dynasties and Ten Kingdoms. These official histories contain records of continuous observations with well-formatted reports conducted under the policy of the governments. A brief comparison of the frequency of observations of sunspots and auroras based on observations of radioisotopes as an indicator of solar activity during the corresponding periods is provided. Using our data, we surveyed and compiled the records of sunspots and auroras in historical documents from various locations and in several languages, and ultimately provide these as open data to the scientific community.

Observational properties of dayside throat aurora and implications on the possible generation mechanisms

AbstractObservational properties of throat aurora are investigated in detail by using 7 year continuous auroral observations obtained at Yellow River Station (magnetic latitude 76.24°N). From our inspection, throat aurora is often observed under the condition of stripy diffuse aurora contacting with the persistent discrete auroral oval, and the long‐period throat aurora observations generally consist of intermittent subsequences of throat aurora brightening followed by poleward moving auroral form and throat aurora dimming. We also noticed that the orientation of throat aurora is aligned along the ionospheric convection flow, and its local time distribution shows clear dependence on the interplanetary magnetic field (IMF) By component. These observational results indicate that factors inside the magnetosphere may play important role on occurrence of throat aurora. We thus suggest that throat aurora may present the ionospheric signature of redistribution of reconnection rate on the magnetopause by cold magnetospheric plasma flowing into the reconnection site. In addition, we also found that the occurrence rate of throat aurora clearly decreases with increase of the IMF cone angle (arccos(|Bx|/B)), which is very similar with the occurrence rate of high‐speed jet (HSJ) observed in magnetosheath depending on the IMF cone angle. This is suggested as that the HSJs occurred outside the magnetosphere may also play important role for generation of throat aurora by triggering magnetopause reconnection or by direct impacting. Although further studies are needed to clarify how the throat auroras are generated in detail, the relevant observations about throat aurora have presented important implications on a variety open questions, such as distribution and generation of cold plasma structures in the outer magnetosphere, magnetopause deformation, and possible relation between HSJ and reconnection.

The earliest drawings of datable auroras and a two-tail comet from the Syriac Chronicle of Zūqnīn

Abstract People have probably been watching the sky since the beginning of human history. Observers in pre-telescopic ages recorded anomalous events, which now provide uniquely valuable information for modern scientists. Records that include drawings are particularly useful, since the verbal expressions recorded by pre-telescopic observers, who did not know the physical nature of the phenomena, are often ambiguous. However, drawings concerning specific datable events in the historical documents are far fewer than the verbal records. Therefore, in this paper we show the possible earliest drawings of datable auroras and a two-tail comet included in a manuscript of the Chronicle of Zūqnīn, a Syriac chronicle up to 775/776 CE, to interpret their nature. Careful perusing the original Syriac autograph manuscript, MS Vat.Sir.162, provide not only historical facts in the realm around Amida, but also information concerning low-latitude aurora observations due to extreme space weather events and the existence of sun-grazing comets.

Earliest datable records of aurora-like phenomena in the astronomical diaries from Babylonia.

The astronomical diaries from Babylonia (ADB) are excellent sources of information of natural phenomena, including astronomical ones, in pre-Christ era because it contains the record of highly continuous and systematic observations. In this article, we present results of a survey of aurora-like phenomena in ADB, spanning from BCE 652 to BCE 61. We have found nine records of aurora-like phenomena. Philological and scientific examinations suggest that five of them can be considered as likely candidate for aurora observations. They provide unique information about the solar and aurora activities in the first millennium BCE. Graphical abstract.

Simultaneous optical and satellite observations of auroras in the mantle: Case study

The all-sky camera data obtained in Barentsburg (Spitsbergen Archipelago) are compared with specific features of electron and ion precipitations on the DMSP F18 satellite during its flight within the camera field of view on December 15, 2012. Before arriving at the cusp from the mantle side, the satellite detects two outbursts of precipitating particles. The burst of mantle precipitations far from the cusp is observed simultaneously in both ionic and electronic components. In the ionosphere related to the satellite, no auroras are detected, which is likely due to the low intensity of the flux of precipitating electrons and their low energy (80 eV). Near the cusp, a more intensive burst of precipitations of higher-energy electrons (140 eV) is accompanied by an almost complete “locking” of ions. This burst of mantle precipitations is related to the faint luminous structure in the ionosphere. The ion locking is indicative of the accelerating potential difference in the force tube, which is based on the glowing region. The luminous structure is an element of the so-called “polewar moving auroral forms,” which is related in the literature to the reconnection in the daytime magnetopause. The possible relation of the observed phenomena to the reconnected magnetic force tubes, which drift from the cusp in the antisolar direction, is also confirmed by the dispersion of ionic precipitations, i.e., an increase in ion energy as the satellite approaches to the cusp.

East Asian observations of low-latitude aurora during the Carrington magnetic storm

Abstract A magnetic storm around 1859 September 2, caused by a so-called Carrington flare, was the most intense in the history of modern scientific observations, and hence is considered to be a benchmark event concerning space weather. The magnetic storm caused worldwide observations of auroras, even at very low latitudes, such as Hawaii, Panama, or Santiago. Available magnetic-field measurements at Bombay, India, showed two peaks: the main was the Carrington event, which occurred in day time in East Asia; a second storm after the Carrington event occurred at night in East Asia. In this paper, we present results from surveys of aurora records in East Asia, which provide new information concerning the aurora activity of this important event. We found some new East Asian records of low-latitude aurora observations caused by a storm which occurred after the Carrington event. The size of the aurora belt of the second peak of the Carrington magnetic storm was even wider than that of usual low-latitude aurora events.

Magnetotail magnetic flux monitoring based on simultaneous solar wind and magnetotail observations

AbstractThe magnetotail magnetic flux (MTF) is an important global variable to describe the magnetospheric state and dynamics. Existing methods of MTF estimation on the basis of the polar cap area, inferred from observations of global auroras and field‐aligned currents, do not allow benchmarking due to the absence of a gauge for comparison; besides, they rarely allow a systematic nearly real time MTF monitoring. We describe three modifications (F0, F1, and F2) of the method to calculate the MTF, based on simultaneous spacecraft observations in the magnetotail and in the solar wind, suitable for real‐time MTF monitoring. The MTF dependence on the solar wind parameters and the observed tail lobe magnetic field is derived from the pressure balance conditions. An essential part of this study is the calibration of our approximate method against global 3‐D MHD simulations and the empirical T14 magnetospheric field model. The calibration procedure provides all variables required to evaluate F0, F1, and F2 quantities and, at the same time, computes the reference MTF value through any tail cross section. It allowed us to extend the method to be used in the near tail, investigate its errors, and define the applicability domain. The method was applied to Cluster and THEMIS measurements and compared with methods of polar cap area calculation based on IMAGE and AMPERE observations. We also discuss possible applications and some recent results based on the proposed method.

A small molecule identified through an in silico screen inhibits Aurora B-INCENP interaction.

Aurora B is a serine/threonine kinase that has a central role in the regulation of mitosis. The observation of Aurora B overexpression in cancer makes it a promising target to develop antitumoral inhibitors. We describe a new potential inhibitor that exclusively targets the interaction site of Aurora B and its activator INCENP. We performed a structure-based virtual screening and determined five potential candidates of 200000 compounds, which selectively bind to the Aurora B::INCENP interaction site, but not to the ATP-binding site (kinase pocket) of Aurora B or other related kinases. Further characterization in vivo validated the inhibitory role of one of these five compounds in Aurora B::INCENP complex formation and exhibited hallmarks of Aurora inhibition such as chromosome congression and segregation defects that interfere with the progression into cytokinesis and result in multinuclear cells. Our results provide an alternative approach on the way of exploring specific kinase inhibitors.

Extraterrestrial light shows

If you want to see an aurora, you could go to the Arctic. Or you could go to Saturn. Sarah Badman explains how observations of auroras on other planets are revealing new facts about these fascinating and beautiful phenomena

Structure of black aurora associated with pulsating aurora

AbstractMorphological behavior of black aurora as it relates to pulsating aurora is investigated by examining a collection of ground‐based observations from January 2007 in support of the Rocket Observations of Pulsating Aurora rocket campaign. Images were sampled from video recorded by a Xybion intensified camera (30 fps) at Poker Flat Research Range, AK. The primary observations of black aurora recorded during the substorm recovery phase were between separate patches of pulsating aurora as well as pulsating aurora separated from diffuse aurora. In these observations the black aurora forms an apparent firm boundary between the auroral forms in a new behavior that is in contrast with previously reported observations. Also presented for the first time are black curls in conjunction with pulsating aurora. Curl structures that indicate shear plasma flows in the ionosphere may be used as a proxy for converging/diverging electric fields in and above the ionosphere. This new subset of black auroral behavior may provide visual evidence of black aurora as an ionospheric feedback mechanism as related to pulsating aurora.

Saturn’s northern auroras as observed using the Hubble Space Telescope

We discuss the features of Saturn’s northern FUV auroras as observed during a program of Hubble Space Telescope observations which executed over 2011–2013 and culminated, along with Cassini observations, in a comprehensive multi-spectral observing campaign. Our 2011–2013 observations of the northern aurora are also compared with those from our 2007–2008 observation of the southern aurora. We show that the variety of morphologies of the northern auroras is broadly consistent with the southern, and determine the statistical equatorward and poleward boundary locations. We find that our boundaries are overall consistent with previous observations, although a modest poleward displacement of the poleward boundaries is due to the increased prevalence of poleward auroral patches in the noon and afternoon sectors during this program, likely due to the solar wind interaction. We also show that the northern auroral oval oscillates with the northern planetary period oscillation (PPO) phase in an elongated ellipse with semi-major axis ∼1.6° oriented along the post-dawn/post-dusk direction. We further show that the northern auroras exhibit dawn-side brightenings at zero northern magnetic PPO phase, although there is mixed evidence of auroral emissions fixed in the rotating frame of the northern PPO current system, such that overall the dependence of the auroras on northern magnetic phase is somewhat weak.

Aurorasaurus: A citizen science platform for viewing and reporting the aurora

AbstractA new, citizen science‐based, aurora observing and reporting platform has been developed with the primary aim of collecting auroral observations made by the general public to further improve the modeling of the aurora. In addition, the real‐time ability of this platform facilitates the combination of citizen science observations with auroral oval models to improve auroral visibility nowcasting. Aurorasaurus provides easily understandable aurora information, basic gamification, and real‐time location‐based notification of verified aurora activity to engage citizen scientists. The Aurorasaurus project is one of only a handful of space weather citizen science projects and can provide useful results for the space weather and citizen science communities. Early results are promising with over 2000 registered users submitting over 1000 aurora observations and verifying over 1700 aurora sightings posted on Twitter.

Variations in the occurrence frequency of Aurora in 1837–1900 from data of the Russian network of meteorological observatories

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 difference was revealed between the behavior of midlatitude (Φ < 56°) and high-latitude auroras during a solar cycle. A peak in the occurrence frequency of aurora dominates at the cycle maximum in midlatitudes; there is an additional maximum during the declining phase. In contrast, the dominant occurrence frequency peak is observed during the declining phase of a solar cycle or at its minimum for high-latitude auroras. In addition, the occurrence frequency of high-latitude aurora increases in 1837–1900. An upward trend in the occurrence frequency of aurora is also observed at the St. Petersburg observatory (Pavlovsk, Φ = 56°). This trend apparently is evidence of an increase in the open regions of solar magnetic fields in 1837–1900. Some parameters of auroral activity also show a 22-year variation.

Concurrent observations of ultraviolet aurora and energetic electron precipitation with Mars Express

AbstractThe database of the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument between late January 2004 and Mars 2014 has been searched to identify signatures of CO Cameron and CO2+ doublet ultraviolet auroral emissions. This study has almost doubled the number of auroral detections based on SPICAM spectra. Auroral emissions are located in the vicinity of the statistical boundary between open and closed field lines. From a total of 113 nightside orbits with SPICAM pointing to the nadir in the region of residual magnetic field, only nine nightside orbits show confirmed auroral signatures, some with multiple detections along the orbital track, leading to a total of 16 detections. The mean energy of the electron energy spectra measured during concurrent Analyzer of Space Plasma and Energetic Atoms/Electron Spectrometer observations ranges from 150 to 280 eV. The ultraviolet aurora may be displaced poleward or equatorward of the region of enhanced downward electron energy flux by several tens of seconds and shows no proportionality with the electron flux at the spacecraft altitude. The absence of further UV auroral detection in regions located along crustal magnetic field structures where occasional aurora has been observed indicates that the Mars aurora is a time‐dependent feature. These results are consistent with the scenario of acceleration of electrons by transient parallel electric field along semiopen magnetic field lines.