Search Results (11)

The establishment of a new green space system based on the green belt has become a new trend in the world. Shanghai’s Outer Ring Ecological Park Belt (formerly the Outer Green Belt) faces challenges of spatial imbalance in recreational service distribution and mismatched supply and demand in functional allocation during its transition from an ecological barrier to a recreational service provider. An approach based on spatial spillover effects serves as a critical solution to address these issues. We integrate RPS and ROS models to build an evaluation framework, map recreational service supply for 2013, 2018, and 2023, delimit core areas via MSPA, and quantify spatial spillovers with models SLM and SEM. The results show that high-value areas of recreational service levels along the ecological park belt have driven the development of neighboring areas through spatial spillovers, with this promoting effect radiating outward from the core zones. As the distance from the core areas increases, the effect weakens, with 400 m as the maximum effect boundary, 1 km as the critical spillover boundary, and unstable effects with decreased significance beyond 2 km. We further conduct localized spatial spillover analysis using representative parks as case studies. The research provides theoretical support and implementation suggestions for the planning and construction of an ecological park belt. Full article

We performed a statistical study on the correlation between electromagnetic Ultra Low Frequency (ULF) waves and the evolution of relativistic electron fluxes in the outer radiation belt for $3.1<L^{\ast }<6.0$ during 101 geomagnetic storms that occurred between January 2013 and November 2018. We used the Van Allen Probes MagEIS and REPT instruments to study electron fluxes from 0.47 MeV to 5.2 MeV, and we utilized magnetic field data from EMFISIS to calculate magnetic field fluctuations parallel and perpendicular to the background magnetic field direction and obtain the ULF integrated power between 1 mHz and 10 mHz. We analyzed the data during the following three different time intervals: the main phase, the recovery phase, and the entire storm. We computed the Pearson’s correlation coefficient and mutual information score between the ratio of fluxes before and after each given phase and the total integrated ULF power during the same time interval. Our results show a significant correlation between ULF wave power and changes in fluxes of hundreds of keV electrons during the main phase of the storms and for MeV electrons during the recovery phase of the storms. By studying fluxes at independent $L^{\ast }$, the largest correlations correspond to changes in fluxes before and after the entire storm and ULF fluctuations parallel to the field, especially for $L^{\ast }<4.6$. We evaluated the drift resonance frequency for azimuthal wavenumber $1\le m\le 10$ and found that for all considered energies and frequencies, the drift resonance with Pc5 ULF waves may occur in our region of study, which is consistent with the statistical results. Full article

Motivated by the need for more accurate radiation environment modeling, this study focuses on identifying and analyzing the drivers behind the sub-relativistic electron flux variations in the inner magnetosphere. We utilize electron flux data between 1 and 500 keV from the Hope and MagEIS instruments on board the RBSP satellites, as well as from the FEEPS instruments on board the MMS spacecrafts, along with solar wind parameters and geomagnetic indices obtained from the OmniWeb2 and SuperMag data services. We calculate the correlation coefficients between these parameters and electron flux. Our analysis shows that substorm activity is a crucial driver of the source electron population (10–100 keV), while also showing that seed electrons (100–400 keV) are not purely driven by substorm events but also from enhanced convection/inward diffusion. By introducing time lags, we observed a delayed response of electron flux to changes in geospace conditions, and we identified specific time lag periods where the correlation is maximum. This work contributes to our broader understanding of the outer belt sub-relativistic electron dynamics and forms the basis for future research. Full article

In solar–terrestrial physics, there is an open question: does a geomagnetic storm affect earthquakes? We expand research in this direction, analyzing the seismic situation after geomagnetic storms (GMs) accompanied by the precipitation of relativistic electrons from the outer radiation belt to form an additional radiation belt (RB) around lower geomagnetic lines. We consider four widely discussed cases in the literature for long-lived (weeks, months) RBs due to GMs and revealed that the 1/GMs 24 March 1991 with a new RB at L~2.6 was followed by an M7.0 earthquake in Alaska, 30 May 1991, near footprint L = 2.69; the 2/GMs 29 October 2003 (Ap = 204) with new RB first in the slot region at L = 2–2.5 cases followed by an M7.8 earthquake on 17 November 2003 at the Aleutian Islands near footprint L = 2.1, and after forming an RB at L~1.5 which lasted for ~26 months, two mega quakes, M9.1 in 2004 and M8.6 in 2005, occurred at the globe; the 3/GMs 3 September 2012 with a new RB at L= 3.0–3.5 was followed by an M7.8 earthquake in Canada near footprint L = 3.2; and the 4/GMs 21 June 2015 with a new RB at L = 1.5–1.8 was followed by an M6.3 earthquake on 7 September 2015 in New Zealand, near footprint L = 1.58. The obtained results suggest that (1) major earthquakes occur near the footprints of geomagnetic lines filled with relativistic electrons precipitating from the outer radiation belt due to geomagnetic storms, and (2) the time delay between geomagnetic storm onset and earthquake occurrence may vary from several weeks to several months. The results may expand the framework for developing mathematical magnetosphere–ionosphere coupling models. Full article

Earth’s radiation belt and ring current are donut-shaped regions of energetic and relativistic particles, trapped by the geomagnetic field. The strengthened solar wind dynamic pressure (P_dyn) can alter the structure of the geomagnetic field, which can bring about the dynamic variation of radiation belt and ring current. In the study, we firstly utilize group test particle simulations to investigate the phase space density (PSD) under the varying geomagnetic field modeled by the International Geomagnetic Reference Field (IGRF) and T96 magnetic field models from 19 December 2015 to 20 December 2015. Combining the observation of the Van Allen Probe, we find that the PSD of outer radiation belt electrons evolves towards different states under different levels of P_dyn. In the first stage, the P_dyn (~7.94 nPa) results in the obvious rise of electron anisotropy. In the second stage, there is a significant reduction in PSD for energetic electrons at all energy levels and pitch angles under the action of intense P_dyn (~22 nPa), which suggests that the magnetopause shadowing and outward radial diffusion play important roles in the second process. The result of the study can help us further understand the dynamic evolution of the radiation belt and ring current during a period of geomagnetic disturbance. Full article

Tracking Ultraviolet Set-up (TUS) on board the Lomonosov satellite measured the UV intensity pulsations in the auroral region. Sixty-four events with pulsations were registered during two measurement periods from 26 December 2016–10 January 2017 and 8–15 November 2017. During both periods, a high-intensity, long-duration, continuous auroral activity (HILDCAA) was detected. Simultaneous measurements in LEO by Lomonosov (DEPRON detector) and Meteor-M2 satellites show the enhanced fluxes of the trapped and precipitated energetic electrons in the region of the Earth’s outer radiation belt during these periods. We found that most of the UV-events correspond to energetic electron (E > 100 keV) precipitation. One can suggest that particles of these and higher energies cause a pulsating emission relatively deep in the atmosphere. Full article

In space, geostationary electronics located within the outer van Allen radiation belt are vulnerable to gamma radiation exposure. In terms of application, implementing an electronic system in a high radiation environment is impossible via conventional engineering materials such as metal alloys as they are prone to radiation damage. Exposure to such radiation causes degradation and structural defects within the semiconductor component, significantly changing their overall density. The changes in the density will then cause electronic failure, known as the single event phenomena. Thus, the radiation response of material must be thoroughly investigated before the material is applied in a harsh radiation environment, specifically for flexible space borne electronic application. In this work, potential candidates for space-borne application devices: zinc oxide (ZnO) and Mg-doped ZnO thin film with a film thickness of 300 nm, were deposited onto an indium tin oxide (ITO) substrate via radio frequency (RF) sputtering method. The fabricated films were then irradiated by Co-60 gamma ray at a dose rate of 2 kGy/hr. The total ionizing dose (TID) effect of ZnO and Mg-doped ZnO thin films were then studied. From the results obtained, degradation towards the surface morphology, optical properties, and lattice parameters caused by increasing TID, ranging from 10 kGy–300 kGy, were evaluated. The alteration can be observed on the morphological changes due to the change in the roughness root mean square (RMS) with TID, while structural changes show increased strain and decreased crystallite size. For the optical properties, band gap tends to decrease with increased dose in response to colour centre (Farbe centre) effects resulting in a decrease in transmittance spectra of the fabricated films. Full article

Moscow State University is developing a project for a multi-satellite constellation intended for the monitoring of space radiation. A number of small satellites of CubeSat format were launched into selected orbits crossing the wide range of magnetic drift shells. The primary scope for the project is the operational monitoring of near-Earth’s radiation environment, i.e., fluxes of electrons and protons of Earth’s radiation belts and energetic particles of solar and galactic origin. To date, there are four CubeSat satellites operating in near-Earth orbits, which deliver scientific and telemetric data. Thus, for the first time, a unique multi-satellite constellation has been implemented, which makes it possible to simultaneously measure the particle and quantum fluxes at different areas in the near-Earth space using the same type of instruments. A special compact detector of gamma quanta and energetic charged particles (electrons and protons) DeCoR has been developed to carry out radiation monitoring by CubeSats. With their help, observations of various effects of space weather have been made. These effects include a variety of electron fluxes in the outer belt during geomagnetic activity in late November–early December 2021, filling of polar caps by solar energetic particles accelerated in flares occurring in late October–early November, and the existence of stable electron fluxes near the geomagnetic equator. Full article

Future commercial, scientific, and other satellite missions require low-Earth-orbit (LEO) altitudes of $300$–$400$ km for long-term successful space operations. The Earth’s radiation belt (ERB) is an inevitable obstacle for manned and other space missions. Precipitation of >$30$ keV energetic electrons from the ERB is one of the sources of ionization in LEO, space vehicles, in the ionosphere, and in the upper atmosphere. We show, in this work, that the area of electron precipitation from the outer ERB shifts equator-wards to Siberia. We further show a substantive decrease in the intensity of energetic electrons in the area of the South Atlantic Anomaly (SAA) from the 23rd to the 24th solar cycles. These results can be attributed to, and explained by, variations in geomagnetic activity, with a noticeable change in the configuration of the Earth’s magnetic field during the 24th solar cycle. The diminishing SAA area and electron fluxes should allow elevation of the International Space Station to higher altitudes, thereby making these altitudes accessible to relevant space missions. Full article

This study reports the temporal and spatial distributions of the extremely/very low frequency (ELF/VLF) wave activities and the energetic electron fluxes in the ionosphere during an intense storm (geomagnetic activity index Dst of approximately −174 nT) that occurred on 26 August 2018, based on the observations by a set of detectors onboard the China Seismo-Electromagnetic Satellite (CSES). A good correlation of the ionospheric ELF/VLF wave activities with energetic electron precipitations during the various storm evolution phases was revealed. The strongest ELF/VLF emissions at a broad frequency band extending up to 20 kHz occurred from the near-end main phase to the early recovery phase of the storm, while the wave activities mainly appeared at the frequency range below 6 kHz during other phases. Variations in the precipitating fluxes were also spotted in correspondence with changing geomagnetic activity, with the max values primarily appearing outside of the plasmapause during active conditions. The energetic electrons at energies below 1.5 MeV got strong enhancements during the whole storm time on both the day and night side. Examinations of the half-orbit data showed that under the quiet condition, the CSES was able to depict the outer/inner radiation belt as well as the slot region well, whereas under disturbed conditions, such regions became less sharply defined. The regions poleward from geomagnetic latitudes over 50° were found to host the most robust electron precipitation regardless of the quiet or active conditions, and in the equatorward regions below 30°, flux enhancements were mainly observed during storm time and only occasionally in quiet time. The nightside ionosphere also showed remarkable temporal variability along with the storm evolution process but with relatively weaker wave activities and similar level of fluxes enhancement compared to the ones in the dayside ionosphere. The ELF/VLF whistler-mode waves recorded by the CSES mainly included structure-less VLF waves, structured VLF quasi-periodic emissions, and structure-less ELF hiss waves. A wave vector analysis showed that during storm time, these ELF/VLF whistler-mode waves obliquely propagated, mostly likely from the radiation belt toward the Earth direction. We suggest that energetic electrons in the high latitude ionosphere are most likely transported from the outer radiation belt as a consequence of their interactions with ELF/VLF waves. Full article

Whistler mode waves play a major role in regulating the lifetime of trapped electrons in the Earth’s radiation belts. Specifically, interaction with whistler mode hiss waves is one of the mechanisms that maintains the slot region between the inner and outer radiation belts. The generation mechanism of hiss is a topic still under debate with at least three prominent theories present in the literature. Lightning generated whistlers in their ducted or non-ducted modes are considered to be one of the possible sources of hiss. We present a study of new observations from the Radio Receiver Instrument (RRI) on the Enhanced Polar Outflow Probe (ePOP: also known as SWARM-E). RRI consists of two orthogonal dipole antennas, which enables polarization measurements, when the satellite boresight is parallel to the geomagnetic field. Here we present 105 ePOP - RRI events from 2014–2018, in which lightning whistlers(75) and hiss waves(39) were observed. In more than 50% of those whistler observations, hiss found to co-exist. Moreover, the whistler observations are correlated with observations of wave power at the lower-hybrid resonance. The observations and a whistler mode ray-tracing study suggest that multiple-hop lightning induced whistlers can be a source of hiss and plasma instabilities in the magnetosphere. Full article