Isolated disturbances such as earthquakes, tsunamis, and solar eclipses, as well as explosions from volcanoes, nuclear detonations, and meteor air bursts can offer discrete tests for models of atmosphere-ionosphere coupling and variability (

We simulate the primary and secondary atmospheric gravity waves (GWs) excited by the upward movement of air generated by the Hunga Tonga‐Hunga Ha'apai (hereafter “Tonga”) volcanic eruption on 15 January 2022. The Model for gravity wavE SOurce, Ray trAcing and reConstruction (MESORAC) is used to calculate the primary GWs and the local body forces/heatings generated where they dissipate. We add these forces/heatings to the HIgh Altitude Mechanistic general Circulation Model (HIAMCM) to determine the secondary GWs and large‐scale wind changes that result. We find that a wide range of medium to large‐scale secondary GWs with concentric ring structure are created having horizontal wind amplitudes of u′, v′ ∼ 100–200 m/s, ground‐based periods of τr ∼ 20 min to 7 hr, horizontal phase speeds of cH ∼ 100–600 m/s, and horizontal wavelengths of λH ∼ 400–7,500 km. The fastest secondary GWs with cH ∼ 500–600 m/s are large‐scale GWs with λH ∼ 3,000–7,500 km and τr ∼ 1.5–7 hr. They reach the antipode over Africa ∼9 hr after creation. Large‐scale temporally and spatially varying wind changes of ∼80–120 m/s are created where the secondary GWs dissipate. We analyze the Tonga waves measured by the Michelson Interferometer for Global High‐resolution Thermospheric Imaging (MIGHTI) on the National Aeronautics and Space Administration Ionospheric Connection Explorer (ICON), and find that the observed GWs were medium to large‐scale with cH ∼ 100–600 m/s and λH ∼ 800–7,500 km, in good agreement with the simulated secondary GWs. We also find good agreement between ICON‐MIGHTI and HIAMCM for the timing, amplitudes, locations, and wavelengths of the Tonga waves, provided we increase the GW amplitudes by ∼2 and sample them ∼30 min later than ICON.

The zodiacal cloud is one of the largest structures in the solar system and strongly governed by meteoroid collisions near the Sun. Collisional erosion occurs throughout the zodiacal cloud, yet it is historically difficult to directly measure and has never been observed for discrete meteoroid streams. After six orbits with Parker Solar Probe (PSP), its dust impact rates are consistent with at least three distinct populations: bound zodiacal dust grains on elliptic orbits (α-meteoroids), unbound β-meteoroids on hyperbolic orbits, and a third population of impactors that may be either direct observations of discrete meteoroid streams or their collisional by-products (“β-streams”). The β-stream from the Geminids meteoroid stream is a favorable candidate for the third impactor population. β-streams of varying intensities are expected to be produced by all meteoroid streams, particularly in the inner solar system, and are a universal phenomenon in all exozodiacal disks. We find the majority of collisional erosion of the zodiacal cloud occurs in the range of 10–20 solar radii and expect this region to also produce the majority of pickup ions due to dust in the inner solar system. A zodiacal erosion rate of at least ∼100 kg s−1 and flux of β-meteoroids at 1 au of (0.4–0.8) × 10−4 m−2 s−1 are found to be consistent with the observed impact rates. The β-meteoroids investigated here are not found to be primarily responsible for the inner source of pickup ions, suggesting nanograins susceptible to electromagnetic forces with radii below ∼50 nm are the inner source of pickup ions. We expect the peak deposited energy flux to PSP due to dust to increase in subsequent orbits, up to 7 times that experienced during its sixth orbit.

Institional Repository GFZpublic: https://gfzpublic.gfz-potsdam.de/ IntroductionIsolated disturbances such as earthquakes, tsunamis, and solar eclipses, as well as explosions from volcanoes, nuclear detonations, and meteor air bursts can offer discrete tests for models of atmosphere-ionosphere coupling and variability (Aryal et al.

Nonlinear ion-acoustic waves, ion holes, and electron holes have been observed on the Parker Solar Probe at a heliocentric distance of 35 solar radii. These time domain structures contain millisecond duration electric field spikes of several mV m−1. They are observed inside or at boundaries of switchbacks in the background magnetic field. Their presence in switchbacks indicates that both electron- and ion-streaming electrostatic instabilities occur there to thermalize electron and ion beams.

As the solar terminator (ST) sweeps through the Earth's atmosphere, sharp gradients in solar illumination across ST and their movement (with both supersonic and subsonic components) can induce disturbances in the atmosphere and ionosphere (Somsikov, 2011). Theoretical calculations and observational studies have focused on ST induced waves, with an emphasis on atmospheric gravity waves (GWs) associated with ST occurring in different layers of the atmosphere (

Within Earth's magnetosphere lie the Van Allen radiation belts, surrounding the Earth with energetic, charged particles. Under typical geomagnetic conditions, there are two such belts-a relatively stable inner belt, and a dynamic outer belt composed of electrons and low-energy protons, typically confined within 3 ≤ L ≤ 8 (e.g., Millan & Baker, 2012;Millan & Thorne, 2007). Outer belt electrons with relativistic energies often remain trapped by Earth's magnetic field for less than a day before either escaping across the magnetopause or precipitating into Earth's atmosphere (Thorne et al., 2005). Precipitating electrons can degrade shortwave radio signals (Evans & Greer, 2000), damage satellite instrumentation (Horne et al., 2013), and produce compounds capable of destroying mesospheric and stratospheric ozone (e.g., Brasseur & Solomon, 2005;Randall et al., 2005). Quantifying the size of the region over which relativistic electron precipitation (REP) occurs will improve understanding of the dynamics in the outer radiation belt, informing future radiation belt and climate models.If a particle's equatorial pitch angle is small enough that its mirror point lies within Earth's atmosphere (<∼100 km above the surface), the particle will likely collide with atmospheric particles and precipitate (Millan & Baker, 2012). Particles are defined to be in the bounce loss cone (BLC) if they will enter the atmosphere within a single bounce period (Selesnick, 2006). Mechanisms such as wave-particle interactions can cause pitch angle scattering, changing affected particle pitch angles, and causing particles that were previously trapped to instead enter the BLC (Millan & Thorne, 2007). Waves capable of pitch angle scattering relativistic electrons include whistler-mode plasmaspheric hiss and chorus, and electromagnetic ion-cyclotron (EMIC) waves (

We report spectroscopy and photometry of the cataclysmic variable stars ASASSN-14ho and V1062 Cyg. Both are dwarf novae with spectra dominated by their secondary stars, which we classify approximately as K4 and M0.5, respectively. Their orbital periods, determined mostly from the secondary stars' radial velocities, proved to be nearly identical, respectively 350.14 ± 0.15 and 348.25 ± 0.60 min. The Hα emission line in V1062 Cyg displays a relatively sharp emission component that tracks the secondary's motion, which may arise on the irradiated face of the secondary; this is not often seen and may indicate an unusually strong flux of ionizing radiation. Both systems exhibit double-peaked orbital modulation consistent with ellipsoidal variation from the changing aspect of the secondary. We model these variations to constrain the orbital inclination i, and estimate approximate component masses based on i and the secondary velocity amplitude K 2 .