Abstract Pulsating auroras (PsAs) are low‐intensity diffuse aurora, which switch on and off with a quasiperiodic oscillation period from few seconds to ∼10 s. They predominantly observed after magnetic midnight, during the recovery phase of substorms at equatorward boundary auroral oval. PsAs caused by precipitating energetic electrons, span wide range energies between tens hundreds keV. Such PsA electrons will deposit their energy mesospheric altitudes induce atmospheric chemical changes....

[1] Magnetic reconnection in the Earth's magnetotail converts open magnetic flux to closed, producing fast flows plasma sheet. Earthward can thus be used as a proxy for energy and momentum transfer into closed magnetosphere during course of substorm. Characteristics observed before substorm onset provide information on role triggering well sequence substorm-related processes. We use 15 years data obtained by Geotail, Cluster, THEMIS study statistically distribution earthward sheet substorms....

Abstract Motivated by recent event studies and modeling efforts on pulsating aurora, which conclude that the precipitation energy during these events is high enough to cause significant chemical changes in mesosphere, this study looks for bulk behavior of auroral pulsations. Based about 400 aurora events, we outline typical duration, geomagnetic conditions, change peak emission height events. We show both green blue decreases 8 km at start interval. This brings hardest 10% electrons down 90...

Quiet, discrete auroral arcs are an important and fundamental consequence of solar wind-magnetosphere interaction. We summarize the current standing observations such arcs. review basic characteristics arcs, including occurrence in time space, lifetimes, width length, as well brightness, energy magnetospheric electrons responsible for optical emission. briefly discuss connection between single multiple The acceleration by high-altitude electric potential structure is reviewed, together with...

Abstract Results from a study of automatic aurora classification using machine learning techniques are presented. The is the manifestation physical phenomena in ionosphere‐magnetosphere environment. Automatic millions auroral images Arctic and Antarctic therefore an attractive tool for developing statistics supporting scientists to objective, organized, repeatable manner. Although previous studies have presented tools detecting aurora, there has been lack classifying into subclasses with...

Abstract. Pulsating aurora (PsA) is a diffuse type of with different structures switching on and off period few seconds. It often associated energetic electron precipitation (>10 keV) resulting in the interaction between magnetospheric electrons electromagnetic waves magnetosphere. Recent studies categorize pulsating into three types – amorphous (APA), patchy (PPA), (PA) based spatial extent pulsations structural stability. Differences energies these have been suggested. In this study, we...

We demonstrate that the Super Dual Auroral Radar Network (SuperDARN) radar at Syowa station, Antarctica, can be used to detect high frequency radio wave attenuation in D region ionosphere during energetic electron precipitation (EEP) events. EEP-related is identified data as a sudden reduction backscatter power and background noise parameters.We focus initially on EEP associated with pulsating aurora use images from colocated all-sky camera validation set for radar-based event detection...

The chemical imprint of the energetic electron precipitation on atmosphere is now acknowledged as a part natural forcing climate system. It has, however, been questioned to which degree current proxies are able quantify medium energy (MEE) (≳30 keV) and associated daily decadal variability. particularly challenging model high tail (≳300 MEE, both in terms intensity well timing. This study explores predictive capabilities AE index for MEE precipitation. measurements from NOAA/POES over full...

Abstract We investigate the role of auroral particle precipitation in small‐scale (below hundreds meters) plasma structuring ionosphere over Arctic. In this scope, we analyze together data recorded by an Ionospheric Scintillation Monitor Receiver (ISMR) Global Navigation Satellite System (GNSS) signals and All‐Sky Imager located Longyearbyen, Svalbard (Norway). leverage on raw GNSS samples provided at 50 Hz ISMR to evaluate amplitude phase scintillation indices 1 s time resolution...

Compositional NOx changes caused by energetic electron precipitation (EEP) at a specific altitude and those co-dependent on vertical transport are referred to as the EEP direct indirect effect, respectively. The effect of lower mesospheric upper stratospheric altitudes is linked high-energy tail (≳ 300 keV). relative importance this NOx, ozone, atmospheric dynamics remains unresolved due inadequate particle measurements scarcity polar observations. An accurate parameterization is, therefore,...

Auroral spirals have different morphologies and origins. In this study, we propose a possible mechanism for the formation of an eastward-moving auroral spiral, which was observed in Tromsø, Norway, during expansion phase substorm on 18 September 2013. During time, Cluster THEMIS-A spacecraft were located ∼7 RE duskward spiral generator region magnetotail. Prior to observation, concurrent magnetic field dipolarizations, bursty bulk flows electron injections measured by...

Twenty‐eight geomagnetic storms driven by magnetic clouds or sheath regions ahead of interplanetary coronal mass ejections are examined to address the dependence driver properties on storm evolution and storm‐substorm relationship. A superposed epoch analysis shows that sheath‐driven have stronger auroral activity, magnetotail field stretching, larger asymmetry in inner magnetosphere configuration. We suggest strong stretching during leaves ions drifting Earthward from plasma sheet open...

The Magnetometers Ionospheric Radars All-sky Cameras Large Experiment (MIRACLE) network monitors auroral activity in the Fennoscandian sector. Network stations cover range of 55° to 57° magnetic latitude north and span two hours local time. Seven MIRACLE include digital all-sky cameras (ASCs). Up recent years, type ASC used consisted an optical system, a charged coupled device (CCD) image intensifier enabling short exposure times. This system is referred as intensified CCD (ICCD) camera. As...

[1] Magnetic activity in the Northern Hemisphere auroral region was examined during solar cycles 22 and 23 (1993–2008). Substorms were identified from ground-based magnetic field measurements by an automated search engine. On average, 550 substorms observed per year, which gives total about 9000 substorms. The interannual, seasonal cycle-to-cycle variations of substorm number (Rss), duration (Tss), peak amplitude (Ass) examined. declining phases both more active than other cycle due to...

Abstract. Substorm properties during different storm phases have been studied using an automated recognition of substorm and in the auroral electrojet (AL) ring current (Dst) index data from 1995–2009. The large number events (about 500 storms 15 000 substorms) provides statistically reliable distributions, average behaviour long time series simple parameters, such as durations intensities. substorms examined independently. further combined to single multi-cycle events. former consist one...

Abstract. We have performed a large statistical study of the peak emission altitude green O(1D2–1S0) (557.7 nm) and blue N2+ 1 N (427.8 aurora using observations from network all-sky cameras stationed across northern Finland Sweden recorded during seven winter seasons 2000 to 2007. Both emissions were found typically at about 114 km. The distribution altitudes is more skewed than that for green, mean 114.84 ± 0.06 116.55 0.07 km emissions, respectively. compare simultaneous measurements two...

Abstract Geomagnetically induced currents (GIC) are a space weather phenomenon that can interfere with power transmission and even cause blackouts. The primary drivers of GIC be represented as ionospheric equivalent currents. We used International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer data from 1994–2013 to analyze the extreme behavior time derivative current density (|Δ J eq |/Δ t ) together occurrence modeled in European high‐voltage grids (1996–2008). Typically,...

Abstract It is well known that auroral patterns at the substorm recovery phase are characterized by diffuse or patch structures with intensity pulsation. According to satellite measurements and simulation studies, precipitating electrons associated these aurorae can reach exceed energies of a few hundreds keV through resonant wave‐particle interactions in magnetosphere. However, because difficulty simultaneous measurements, dependency energetic electron precipitation (EEP) on morphological...

Abstract. A total of 10 radars from the Super Dual Auroral Radar Network (SuperDARN) in Antarctica were used to estimate spatial area over which energetic electron precipitation (EEP) impacts D-region ionosphere during pulsating aurora (PsA) events. We use an all-sky camera (ASC) located at Syowa Station confirm presence optical PsAs, and then we SuperDARN detect high frequency (HF) radio attenuation caused by enhanced ionisation ionosphere. The HF was identified visually examining...

Abstract. The 10 May 2024 geomagnetic storm was one of the most extreme to have occurred in over 20 years. In era smartphones and social media, millions people from all around world were alerted possibility exceptional auroral displays. Hence, many not only witnessed but also photographed aurora during this event. These observations, although traditional scientific instruments, can prove invaluable obtaining data characterise extraordinary particular, observers saw at mid-latitudes, where...

Statistical properties of storm time magnetospheric activity are examined using superposed epoch analysis. We show that about half auroral electrojet activations have signatures typical nonstorm substorms, including geostationary orbit injections and magnetic field dipolarizations. Analysis a separate data set sawtooth events shows they inner magnetosphere characteristics quite similar to those found generally during activity. Hence it is concluded the do not represent specific class...

Every winter, the all-sky cameras (ASCs) in MIRACLE network take images of night sky at regular intervals 10-20 s. This amounts to millions that not only need be pruned, but there is also a for efficient auroral activity detection techniques. In this paper, we describe method performing automated classification ASC into three mutually exclusive classes: aurora, no and cloudy. reduces amount data processed, facilitates building statistical models linking magnetic fluctuations helping us get...

Abstract This study investigates the contribution of energetic ( E > 30 keV) particle precipitation during a pulsating aurora event over Kilpisjärvi L = 6.2) on 26 February 2014. It is based comparison auroral blue‐line emission (427.8 nm) data from an all‐sky camera and cosmic noise absorption (CNA) obtained multibeam experiment Atmospheric Imaging Receiver Array (KAIRA) riometer. The sets are compared for three KAIRA beams close to magnetic zenith. Results show clear correlation between...