Curtain precipitation is a recently discovered stationary, persistent, and latitudinally narrow electron precipitation phenomenon in low Earth orbit. Curtains are observed over consecutive passes of ...the dual AeroCube‐6 CubeSats while their in‐track lag varied from a fraction of a second to 65 s, with dosimeters that are sensitive to >35‐keV electrons. This study uses the AeroCube‐6 mission to quantify the statistical properties of 1,634 curtains observed over 3 years. We found that many curtains are narrower than 10 km in the latitudinal direction with 90% narrower than 20 km. We examined the geographic, magnetic local time, and geomagnetic dependence of curtains. We found that curtains are observed in the late‐morning and premidnight magnetic local times, with a higher occurrence rate at premidnight, and curtains are observed more often during times of enhanced Auroral Electrojet. We found a few curtains in the bounce loss cone region above the North Atlantic, whose electrons were continuously scattered for at least 6 s. Such observations suggest that continuous curtain precipitation may be a significant loss of >35‐keV electrons from the magnetosphere into the atmosphere. We hypothesize that the curtains observed in the bounce loss cone were accelerated by parallel electric fields, and we show that this mechanism is consistent with the observations.
Plain Language Summary
Electron curtain precipitation from space into Earth's atmosphere is a recently discovered phenomenon observed by dual‐spacecraft missions such as the AeroCube‐6 CubeSats that are nearly in the same orbit, ≈700 km above Earth's surface. Curtains appear stationary between consecutive passes of the AeroCube‐6 CubeSats, while the leader CubeSat was ahead of the follower CubeSat by up to a minute in orbital time. Curtains are also very narrow along the satellite orbit that is mostly in the latitudinal direction. Besides these two properties, curtains and their impact on the magnetosphere and atmosphere are not well understood. Therefore, we used the AeroCube‐6 mission that took data together for 3 years to statistically quantify curtain properties and to better understand their origin. We found 1,634 curtains and found that 90% of curtains are narrower than 20 km in the latitudinal direction, curtains are observed on the outer radiation belt field lines predominately in the antisunward region, and curtains are observed when the magnetosphere is disturbed. Curtains observed in a special region above the North Atlantic shed light on their origin. A surprising result is that a few dozen curtains observed in this North Atlantic region were continuously precipitating into the atmosphere for multiple seconds. Therefore, curtains may be a significant source of atmospheric ionization responsible for the natural depletion of ozone.
Key Points
The dual AeroCube‐6 CubeSats are used to identify stationary, narrow in latitude, and persistent >35‐keV electron curtain precipitation
Ninety percent of the observed curtains in low Earth orbit are narrower than 20 km in the latitudinal direction
Some curtains continuously precipitated into the atmosphere for multiple seconds
We present the first evidence of electron microbursts observed near the equatorial plane in Earth's outer radiation belt. We observed the microbursts on 31 March 2017 with the Magnetic Electron Ion ...Spectrometer and Radiation Belt Storm Probes Ion Composition Experiment on the Van Allen Probes. Microburst electrons with kinetic energies of 29–92 keV were scattered over a substantial range of pitch angles, and over time intervals of 150–500 ms. Furthermore, the microbursts arrived without dispersion in energy, indicating that they were recently scattered near the spacecraft. We have applied the relativistic theory of wave‐particle resonant diffusion to the calculated phase space density, revealing that the observed transport of microburst electrons is not consistent with the hypothesized quasi‐linear approximation.
Plain Language Summary
Microbursts are a subsecond impulsive increase of electron precipitation from the outer Van Allen radiation belt into the atmosphere, believed to be an important loss process of radiation belt electrons. One possible source of microbursts is scattering of trapped radiation belt electrons by a plasma wave called chorus. Diffusion models show that chorus can both accelerate and scatter electrons into the atmosphere. Since microbursts have been previously observed by high‐altitude balloons and low Earth orbiting spacecraft, there has been little evidence that directly link the chorus wave and the microburst that it generated. We show evidence of microbursts and their progenitor waves observed deep inside the outer radiation belt by the Van Allen Probes spacecraft. The Van Allen Probes are configured to extensively study the wave and particle environment in the magnetosphere, which allows us to understand the microbursts' energy dependence, angular extent, and the scattering mechanism. This unique perspective enables us to understand how these electrons were transported by the chorus wave, and compare it to a hypothesized quasi‐linear diffusion model. Our results indicate that the observed transport of microburst electrons was not consistent with the hypothesized diffusion model.
Key Points
The first report of direct observation of microbursts at high altitude, near the equatorial plane
Microbursts' duration, flux enhancement, and energy spectra are similar to prior observations in LEO
Microburst generation is not consistent with a single quasi‐linear gyroresonant interaction with chorus waves
Age-associated disorders of the function of maintaining balance lead to an increase in the frequency of falls and related complications (injuries, limited mobility, decreased independence and ...autonomy, etc.). In addition, motor disorders of various genesis in most cases are accompanied by changes in postural function. An analytical review of the literature over the last decade devoted to methods of assessing postural balance in older age groups has been conducted. Computer stabilometry is recognized as the best method for an objective assessment of postural function and dynamic monitoring of the effectiveness of therapy. At the same time, the stabilometric characteristics of postural disorders in older age groups and the relationship between the indicators of stabilography and age remain insufficiently studied.
Within the context of the Heliophysics System Observatory, optical images of the aurora are emerging as an important resource for exploring multi-scale geospace processes. This capability has never ...been more critical as we are on the cusp of a new era of geospace research, by which we mean studying the overall system as a
system of systems
. Historically, the patchwork of ground-based instrumentation has required customized solutions for accessing data, assessing data relevance, and then ultimately using each individual network alongside other assets. Here we introduce a new and comprehensive approach for data discovery and utilization for one type of data, namely auroral images. The AuroraX project (
https://aurorax.space/
) is a cyberinfrastructure platform for the discovery of scientific opportunities with access to optical auroral data. The program has broad objectives, so we focus on one key thread. In particular, we focus on describing the AuroraX platform and its API and web-based tools for all-sky imager (ASI) data. As a practical example, we demonstrate how to identify conjunctions using the AuroraX conjunction finder or PyAuroraX, a Python library that interfaces with the AuroraX platform. We then demonstrate how aurora-asi-lib, a Python library for interacting with and analyzing high-resolution ASI data, can be used for detailed conjunction analysis on a personal computer. Together, these tools enable a rapid and streamlined end-to-end exploration of auroral data.
We made observations of magnetic field variations in association with pulsating auroras with the magneto‐impedance sensor magnetometer (MIM) carried by the Loss through Auroral Microburst Pulsations ...(LAMP) sounding rocket that was launched at 11:27:30 UT on 5 March 2022 from Poker Flat Research Range, Alaska. At an altitude of 200–250 km, MIM detected clear enhancements of the magnetic field by 15–25 nT in both the northward and westward components. From simultaneous observations with the ground all‐sky camera, we found that the footprint of LAMP at the 100 km altitude was located near the center of a pulsating auroral patch. The auroral patch had a dimension of ∼90 km in latitude and ∼25 km in longitude, and its major axis was inclined toward northwest. These observations were compared with results of a simple model calculation, in which local electron precipitation into the thin‐layer ionosphere causes an elliptical auroral patch. The conductivity within the patch is enhanced in the background electric field and as a result, the magnetic field variations are induced around the auroral patch. The model calculation results can explain the MIM observations if the electric field points toward southeast and one of the model parameters is adjusted. We conclude that the pulsating auroral patch in this event was associated with a one‐pair field‐aligned current that consists of downward (upward) currents at the poleward (equatorward) edge of the patch. This current structure is maintained even if the auroral patch is latitudinally elongated.
Key Points
Magneto‐impedance (MI) sensor was carried by a sounding rocket and first applied to magnetic field measurement in space
Magnetic field variations were observed when the footprint of the payload was located near the center of an auroral patch
The magnetic field variations are thought to be caused by field‐aligned currents flowing at the edges of the pulsating auroral patch
The post-irradiation recovery annealing of grade 14Kh17N2 steel used in the intermediate control bayonets of WWER reactors is optimized. It is shown that the proposed heat treatment conditions ...completely recover the mechanical properties of the bayonet metal embrittled under neutron irradiation. That said, the chosen conditions do not reduce the corrosion resistance of the intermediate rod pipe made of grade 08Kh18N10T austenitic steel.
Microbursts are impulsive (<1s) injections of very energetic to relativistic electrons (energies from a few keV to MeV) into Earth’s atmosphere. They are important because they may represent a major ...loss process for the outer radiation belt (Ripoll and Claudepierre and Ukhorskiy and Colpitts and Li and Fennell and Crabtree, J. Geophys. Res. Space Physics, 2020, 125–e2019JA026735). Understanding and quantifying the underlying causes and consequences plus relative importance of microburst precipitation represent outstanding questions in radiation belt physics and may have significant implications ranging from space weather to atmospheric chemistry. Chorus waves are the likely dominant cause of microburst precipitation, but important questions remain regarding the exact nature of the resonance generating the microbursts and the overall importance of the precipitation. These important questions are limited by lack of systematic coordination of simultaneous observations of causative waves in the magnetosphere and resulting precipitating particles at low altitudes. Multi-spacecraft missions dedicated to answering these questions, themselves required to make progress in radiation belt physics, are critical.
Charged particle precipitation from Earth’s magnetosphere results in stunning displays of the aurora and energy transfer into the atmosphere. Some of this precipitation is caused by wave-particle ...interactions. In this study, we present an example of a wave-particle interaction between Electromagnetic Ion Cyclotron waves, and magnetospheric protons and electrons. This interaction resulted in a co-located isolated proton aurora and relativistic electron microbursts. While isolated proton aurora is widely believed to be caused by Electromagnetic Ion Cyclotron waves, this unique observation suggests that these waves can also scatter relativistic electron microbursts. Theoretically, nonlinear interactions between Electromagnetic Ion Cyclotron waves and electrons are necessary to produce the intense sub-second microburst precipitation. Lastly, detailed analysis of the auroral emissions suggests that no chorus waves were present during the event. This is in contrast to the most commonly associated driver of microbursts, whistler mode chorus waves, and supports other less commonly considered driving mechanisms.
This study considers the impact of electron precipitation from Earth's radiation belts on atmospheric composition using observations from the NASA Van Allen Probes and NSF Focused Investigations of ...Relativistic Electron Burst Intensity, Range, and Dynamics (FIREBIRD II) CubeSats. Ratios of electron flux between the Van Allen Probes (in near‐equatorial orbit in the radiation belts) and FIREBIRD II (in polar low Earth orbit) during spacecraft conjunctions (2015–2017) allow an estimate of precipitation into the atmosphere. Total Radiation Belt Electron Content, calculated from Van Allen Probes RBSP‐ECT MagEIS data, identifies a sustained 10‐day electron loss event in March 2013 that serves as an initial case study. Atmospheric ionization profiles, calculated by integrating monoenergetic ionization rates across the precipitating electron flux spectrum, provide input to the NCAR Whole Atmosphere Community Climate Model in order to quantify enhancements of atmospheric HOx and NOx and subsequent destruction of O3 in the middle atmosphere. Results suggest that current APEEP parameterizations of radiation belt electrons used in Coupled Model Intercomparison Project may underestimate the duration of events as well as higher energy electron contributions to atmospheric ionization and modeled NOx concentrations in the mesosphere and upper stratosphere.
Plain Language Summary
High‐energy particles precipitating into the atmosphere from space affect the chemistry and composition of Earth's atmosphere. While there is significant understanding about the atmospheric impacts of auroral electrons, solar protons, and galactic cosmic rays, the effects of electrons from the near‐Earth Van Allen radiation belts remain uncertain. This study helps quantify electrons precipitating into the atmosphere by comparing measurements within the radiation belts from the NASA Van Allen Probes spacecraft to observations from the low‐altitude NSF Focused Investigations of Relativistic Electron Burst Intensity, Range, and Dynamics (FIREBIRD II) CubeSats. Global atmospheric model simulations quantify the impact of estimated electron precipitation on the ionization and chemical composition of Earth's atmosphere. Results from an initial case study using this new method suggest that electrons from the radiation belts may produce more atmospheric ionization at lower altitudes and for longer duration than currently recommended estimates, potentially affecting the chemistry of ozone in the middle atmosphere and as a consequence influencing atmospheric heating and dynamics.
Key Points
Conjunctions between Van Allen Probes and FIREBIRD II enable novel estimates of atmospheric electron precipitation
Estimates of electron precipitation from Van Allen Probes suggest CMIP6 may underestimate atmospheric ionization from 60 to 70 km
Direct production of NOx by precipitating electrons during March 2013 using this new method suggest 40% enhancements from 60 to 70 km
PDF
