Space Environment Monitor Research Articles

Do Solar Energetic Particle (SEP) Events Influence the Formation of the V0 Layer in the Venusian Ionosphere?

AbstractThis study investigates the potential impact of Solar Energetic Particles (SEPs) on the V0 layer of the Venus ionosphere. Electron density profiles obtained from radio occultation experiments conducted by the Venus Express (VEX) and Akatsuki missions were utilized for this purpose. Background data from the Analyzer of Space Plasma and EneRgetic Atoms (ASPERA‐4) aboard VEX were used to detect SEP events. Additionally, observations from the Space Environment Monitor (SEM) suite onboard the Geostationary Operational Environmental Satellite (GOES) during alignments of Venus, Earth, and the Sun were also considered. Our findings indicate that while SEPs may contribute to the formation of the V0 layer, they are not the main driving force in the Venusian ionosphere.

The Relationship Between Electron Precipitation and the Population of Trapped Electrons in LEO: New Evidence Supporting a Natural Limit to the Flux of Energetic Electrons

AbstractEnergetic particle precipitation into the atmosphere has been identified as a key loss process for electrons in the Earth's outer radiation belt region. However, direct measurements of the electron flux precipitating into the atmosphere are challenging from high altitude low inclination spacecraft, such as the Van Allen Probes, due to the small angular size of the loss cone along the orbital path of these high‐altitude spacecraft. Here we use data from the Polar Orbiting Environmental Satellites (POES)/Space Environment Monitor in low‐Earth orbit to assess the relationship between the trapped and precipitating electron flux in integral energy channels >30, >100, and >300 keV. Our results highlight that there is a strong non‐linear relationship between the flux of trapped and precipitating electrons, with the ratio of precipitating to trapped flux only becoming significantly enhanced once the trapped flux reaches a critical level. This transition from low to high levels of precipitation is consistent with the theory proposed by Kennel and Petschek (K‐P) (1966) https://doi.org/10.1029/JZ071i001p00001, whereby intense chorus waves are excited and trigger pitch angle diffusion, resulting in energetic particle precipitation and limiting the trapped flux. Using electron flux data from POES and chorus wave data from the Van Allen Probes, we further test the observations against predictions from the K‐P theory. A particle tracing model is also utilized to illustrate a direct link between the drift paths of injected electrons, the occurrence of chorus waves and the spatial distribution of strong electron precipitation into the atmosphere at different energies.

Van Allen Belt Punctures and Their Correlation With Solar Wind, Geomagnetic Activity, and ULF Waves

AbstractWe investigate the rare events of sudden appearances of relativistic electrons (>700 keV), which are normally confined to the Van Allen belts, in the slot region. The frequency of occurrence of these events is on average 1–2 per year. To cope with the scarcity of events, in this study, we examine 21 years of trapped relativistic electron fluxes available from the POES and MetOp Space Environment Monitor (SEM‐2). Our statistical analysis shows that these events can occur even during moderate geomagnetic activity. Occurrence of these events correlates with high‐speed solar winds or interplanetary coronal mass ejections depending on the phase of the solar cycle. A strong correlation of these events is found with ultra‐low frequency (ULF) wave activity, which can be used to predict these events with more than 75% accuracy.

Spatial Distributions of Nitric Oxide in the Antarctic Wintertime Middle Atmosphere During Geomagnetic Storms

AbstractEnergetic electron precipitation leads to increased nitric oxide (NO) production in the mesosphere and lower thermosphere. NO distributions in the wintertime, high‐latitude Southern Hemisphere atmosphere during geomagnetic storms are investigated. NO partial columns in the upper mesosphere at altitudes 70–90 km and in the lower thermosphere at 90–110 km have been derived from observations made by the Solar Occultation For Ice Experiment (SOFIE) on board the Aeronomy of Ice in the Mesosphere (AIM) satellite. The SOFIE NO measurements during 17 geomagnetic storms in 2008–2014 have been binned into selected geomagnetic latitude and geographic latitude/longitude ranges. The regions above Antarctica showing the largest instantaneous NO increases coincide with high fluxes of 30–300 keV precipitating electrons from measurements by the second‐generation Space Environment Monitor (SEM‐2) Medium Energy Proton and Electron Detector (MEPED) instrument on the Polar‐orbiting Operational Environmental Satellites (POES). Significant NO increases over the Antarctic Peninsula are likely due to precipitation of >30 keV electrons from the radiation belt slot region. NO transport is estimated using Horizontal Wind Model (HWM14) calculations. In the upper mesosphere strong eastward winds (daily mean zonal wind speed ~20–30 m s−1 at 80 km) during winter transport NO‐enriched air away from source regions 1–3 days following the storms. Mesospheric winds also introduce NO‐poor air into the source regions, quenching initial NO increases. Higher up, in the lower thermosphere, weaker eastward winds (~5–10 m s−1 at 100 km) are less effective at redistributing NO zonally.

The Possible Responses of Polar Ozone to Solar Proton Events in March 2012 by FengYun‐3 Satellite Observations

AbstractIn this work, we use observations by the Solar Backscatter Ultraviolet Sounder and Space Environment Monitor on FengYun‐3 to analyze the polar ozone depletion during the solar proton events (SPEs), which occurred in early March 2012. The ozone distributions changed evidently with the increasing energetic proton flux (the particle energy is over 100 MeV) at the approximate altitude of 30 km. From the ozone profile relative changes, the short‐term impacts of SPEs can be distinguished from the long‐term effects of ozone season variations after the SPEs take place and cause about 4–17% of the short‐term polar ozone decreases at the different levels in the upper stratosphere of both hemispheres. In the upper stratosphere, the SPE‐related polar ozone depletion is more significant and continuous in the Northern Hemisphere but shows the short‐term effects in the Southern Hemisphere during the March SPEs. The ozone depletion responses to the first SPE on 7 March are more pronounced in this altitude region than the second one on 13 March in both hemispheres due to the “harder” particle energy spectrum.

Space Environment Monitor and Preliminary Results of HXMT Satellite

硬X射线调制望远镜（HXMT）卫星是中国首个专门进行天文探测的空间科学实验卫星，运行于高度约550km、倾角约43°的低地球轨道.星载空间环境监测器为星上科学任务开展提供背景辐射实测资料.该监测器采用固体探测器望远镜系统和扇形阵列全新组合设计，可获取轨道空间高能质子和高能电子能谱、方向综合动态结果，给出更为全面的粒子辐射分布图像.初步探测结果显示，卫星运行轨道遭遇的带电粒子辐射集中分布在经度80°W-20°E，纬度0°-40°S的南大西洋异常区，粒子辐射在该区域表现出不同程度的方向差异分布，高能电子方向差异分布显著强于高能质子.2017年9月空间环境扰动期间，爆发的太阳质子事件并未对该轨道粒子辐射产生影响，而地磁活动导致该轨道穿越经度120°W-60°E，纬度40°-43°N的北美上空和经度60°-120°E，纬度43°-40°S的澳大利亚西南区域时遭遇增强粒子辐射影响，增强的粒子辐射表现出极强的方向分布.

First Ionospheric Radio-Occultation Measurements From GNSS Occultation Sounder on the Chinese Feng-Yun 3C Satellite

The Global Navigation Satellite System Occultation Sounder (GNOS) has been planned for the five Feng-Yun 3 series (FY3) weather satellites since 2013, the first of which, the FY3C satellite, was launched successfully at 03:07 UTC on September 23, 2013 from the Taiyuan Satellite Base, Shanxi province, China, into the orbit of 836-km altitude and 98.75° inclination. In addition to the Global Positioning System (GPS), the FY3C/GNOS is capable of tracking the occultation signal of the BeiDou Navigation Satellite System (BDS) (also called COMPASS) from space for the first time. The quality of BDS radio occultation (RO) has been verified in terms of signal-to-noise ratio. In this paper, the electron density profiles (EDPs) observed by FY3C/GNOS from both GPS RO and BDS RO, which were processed and archived in the National Satellite Meteorological Center of China Meteorological Administration, are compared with 32 globally distributed ionosonde observations, and then, we compare GPS RO EDPs with ionosonde observations at Mohe (52.0° N, 122.5° E), Beijing (40.3° N, 116.2° E), Wuhan (31.0° N, 114.5° E), and Sanya (18.3° N, 109.6° E). FY3C/GNOS EDPs show good agreement with ionosonde measurements, with larger discrepancies near the equatorial ionization anomaly region at Wuhan and Sanya. The ionospheric peak density (NmF2) and peak height (hmF2) derived from FY3C/GNOS EDPs are also compared with those obtained from the globally distributed ionosondes for the day of year 274–365 in 2013. In general, NmF2 and hmF2 have a higher correlation coefficient in the middle–high latitude than in the lower latitude region, due to the difference of ionospheric horizontal inhomogeneity. We also compared the NmF2 and hmF2 maps between FY3C/GNOS and the International Reference Ionosphere 2012 (IRI-2012) model. However, the wavenumber-4 structure, which can be indicated clearly from FY3C/GNOS observations, could not be reproduced well by IRI-2012. Further investigations show that the nighttime EDPs have obvious ionization enhancement around the ionospheric E layer over the Aurora and the South Atlantic Anomaly regions due to the energetic particle precipitation indicated by the Space Environment Monitor observations onboard FY3C.

The Capabilities and Applications of FY-3A/B SEM on Monitoring Space Weather Events

The space environment monitor (SEM), onboard the Chinese meteorological satellites FengYun-3A/B, has the abilities to measure proton flux in 3-300-MeV energy range and electron flux in 0.15-5.7-MeV energy range. SEM can also detect the heavy ion compositions, satellite surface potential, the radiation dose in sensors, and the single events. The space environment information derived from SEM can be utilized for satellite security designs, scientific studies, development of radiation belt models, and space weather monitoring and disaster warning. In this paper, the SEM's instrument characteristics are introduced, and the postlaunch calibration algorithm is presented. The applications in monitoring space weather events and the service for manned spaceflights are also demonstrated.

Interannual variation of NOxfrom the lower thermosphere to the upper stratosphere in the years 1991-2005

[1] The interannual variation of NOx throughout the year is investigated for the period 1991–2005 at middle to high latitudes using Halogen Occultation Experiment (HALOE) on UARS measurements. We find a clear correlation of NOx between 80 and 130 km with the auroral electrojet index in both hemispheres, which is fairly independent of season, indicating a relatively frequent NOx source from precipitating auroral electrons of energies ranging from about 1 keV to several tens of keV. Between 80 and 100 km, NOx is also highly correlated to fluxes of higher-energy electrons as measured by the Space Environment Monitor (SEM) and its successor, the SEM-2, instruments on POES mostly during autumn and spring, indicating a strong impact of 10–100 keV electrons, which, however, precipitate less frequently than the auroral electrons. Electrons with energies of several MeV were investigated also, and a significant correlation was found with NOx during some periods. The correlation is smaller and less stable than for the lower-energetic auroral and POES electrons, indicating that the contribution of MeV electrons to the overall NOy budget is small, at least in the latitude range considered. Also, the altitude range affected, above 60 km, indicates that this impact is probably due to electrons of lower energies (several hundreds of keV instead of several MeV) than the GOES electrons used for the investigation, to which they must be closely related, however. Downward propagation of NOx is observed in both hemispheres during winter but continues to lower altitudes and lasts longer in the Southern Hemisphere, where the signal can be followed to altitudes around 40 km.

Use of POES SEM‐2 observations to examine radiation belt dynamics and energetic electron precipitation into the atmosphere

The coupling of the Van Allen radiation belts to the Earth's atmosphere through precipitating particles is an area of intense scientific interest. Currently, there are significant uncertainties surrounding the precipitating characteristics of medium energy electrons (>20 keV), and even more uncertainties for relativistic electrons. In this paper we examine roughly 10 years of measurements of trapped and precipitating electrons available from the Polar Orbiting Environmental Satellites (POES)/Space Environment Monitor (SEM‐2), which has provided long‐term global data in this energy range. We show that the POES SEM‐2 detectors suffer from some contamination issues that complicate the understanding of the measurements, but that the observations provide insight into the precipitation of energetic electrons from the radiation belts, and may be developed into a useful climatology for medium energy electrons. Electron contamination also allows POES/SEM‐2 to provide unintended observations of >700 keV relativistic electrons. Finally, there is an energy‐dependent time delay observed in the POES/SEM‐2 observations, with the relativistic electron enhancement (electrons >800 keV) delayed by approximately one week relative to the >30 keV electron enhancement, probably due to the timescales of the acceleration processes. Observations of trapped relativistic electron fluxes near the geomagnetic equator by GOES show similar delays, indicating a “coherency” to the radiation belts at high and low orbits, and also a strong link between trapped and precipitating particle fluxes. Such large delays should have consequences for the timing of the atmospheric impact of geomagnetic storms.

Long-term observations of the trapped high-energy proton population ( L < 4) by the NOAA Polar Orbiting Environmental Satellites (POES)

The Space Environment Monitor (SEM) onboard the NOAA POES satellites has been measuring the near-Earth charged particle environment since 1978, providing an extensive database that can be used for studying the long-term behavior of this population of trapped particles. POES stands for Polar Orbiting Environmental Satellite. These satellites orbit at ∼840 km altitude and at an inclination of 98°. The SEM-1 instrument was flown on the POES satellites beginning in 1978 with TIROS-N and NOAA-6 in 1979 and continuing to NOAA-14 launched in 1995 with the exception of NOAA-9 and NOAA-11 (NOAA-13 failed shortly after launch). Its replacement, SEM-2, has flown on the POES NOAA-15, -16, and -17 satellites (from 1998). Here we present the results of a study on the statistical variations of the high-energy trapped proton environment. Among the detectors in SEM, the four SEM-2 omni-directional proton detectors for energies >16 MeV, >36 MeV, >70 MeV, and >140 MeV provide the data most relevant to this study. For this study, the SEM-2 omni-directional detector data from each satellite (NOAA-15, -16, and -17) were accumulated over 8-s intervals and arranged/collected on a 1° latitude by 2° longitude grid. The data set covers the period between June 1, 1998 and June 30, 2005. This amounts to about 15 satellite-years of data encompassing much of a solar cycle. The spatial grid covers sub-satellite locations at latitude center values from 65.5° north to 72.5° south and longitude center values from 1° east to 359° east. Typically there are 1700–2100 individual data entries per detector within each longitude–latitude bin. For each spatial bin, we also computed for detailed analysis various geomagnetic field parameters (e.g., McIlwain’s L value, local field strength, field strength at the equator along the field line, etc.) for the field line threading the center of the bin. For this purpose, we used the International Geomagnetic Reference Field (IGRF) Model, Epoch 2003.5. Each data sample within the spatial bin also contains the information on geomagnetic activity and an index indicating whether a Solar Energetic Particle (SEP) event was in progress at the time the data were taken and the magnitude of that event. The final data set thus obtained forms an extensive source of information useful for studying the long-term near-Earth trapped proton environment as a function of solar cycle, magnetic activity and the role of SEP events.

Response of Medium Energy Electrons Fluxes to Geomagnetic Disturbance at Low Orbit

低轨道高度上能量电子通量变化与地磁扰动程度密切相关.利用我国资源2号(ZY-2)03星空间环境监测分系统在轨工作期间所获得的能量电子探测数据,以及美国NOAA-15,NOAA-16,NOAA-17三颗卫星中等能量电子探测器自1998年以来积累的太阳同步轨道中等能量电子探测数据,结合地磁活动观测数据,对低轨道高度上中等能量电子对地磁扰动的响应特性进行了统计分析.结果表明,该区域的中等能量电子通量在磁暴、磁层亚暴期间有显著增强,增幅大小与地磁活动程度呈正相关关系,强磁暴期间增幅可达一个数量级左右,在响应时间上存在电子通量变化滞后于磁扰的时间特性.

Mission objectives and payloads for the first lunar exploration of China

China plans to implement its first lunar exploration by 2007. The mission objectives are: obtaining the lunar surface three-dimensional stereo image; analyzing the distribution of the useful elements and estimating their abundance, surveying the thickness of lunar soil and evaluating resource of He-3, exploring the environment between the Moon and Earth. To achieve the above mission goals, five kinds of scientific instruments are chosen as the payloads of the lunar satellite. These include stereo camera and Sagnac-based interferometer spectrometer imager, laser altimeter, microwave radiometer, gamma and X-ray spectrometer system and space environment monitor system. In order to collect, process, store and transmit the scientific data of the payloads a special payload data management system (PDMS) is also included. In this paper, the goals of Chinese first lunar exploration and the payloads of the lunar satellite are described in detail.

The space environment monitor aboard FY-2 satellite

The space environment monitor aboard FY-2 satellite

The space environment monitor aboard FY-2 satellite

The space environment monitor (SEM) aboard FY-2 satellite consists of the high energy particle detector (HEPD) and the solar X-ray flux detector (SXFD). The SEM can provide real-time monitoring of flare and solar proton event for its operation at geostationary orbit and is also the first Chinese space system for monitoring and alerting solar proton event. During the 23rd solar maximum cycle, almost all the solar proton events that took place in this period are monitored and some of them are predicted successfully by analyzing the characteristics of X-ray flare monitored by the SEM. Some basic variation characteristics of particle at geostationary orbit are found such as day-night periodic variation of particle flux, the electron flux with energy > 1.4 MeV in the scope from 10 to 200/cm(2)circle s circle sr and the proton flux with energy > 1.1 MeV in the scope from 600 to 8000/cm(2)circle s circle sr during the time with no magnetic storm and solar eruption.

Forecasting electron precipitation based on predicted geomagnetic activity

We have developed a statistical model of precipitating electrons based on 10 years worth of NOAA-12 Space Environment Monitor (SEM) data. For each hour of UT, the electron spectral shape is defined for solar activity (using F 10.7), geomagnetic activity (using Dst, Kp, and PC), invariant latitude (40 to 90°N and −40° to −90°S), and every hour of magnetic local time to form a climatology. The current version of our climatology includes a description of the precipitating differential number flux, unfolded from the integral high-energy telescopes of SEM and its lower-energy differential measurements. In total, the energy range covered by SEM is from 300 eV to 1 MeV. We use real-time Dst predictions from several sites on the Internet which forecast Dst up to 1 h ahead of time to predict the corresponding precipitating electron flux. Our electron precipitation forecast contributes to space weather applications by predicting a spectral description of atmospheric electron energy input. These electron energy spectra can be used to generate atmospheric energy input, ionization rates and height-integrated Hall and Pedersen conductivities, which are important parameters to models such as AMIE and TIME-GCM. Our data could also improve the space environment description used in spacecraft charging models.

Comparison of common climatology data

Over the past few years, climatologies of precipitating electrons have been developed for several instruments on different satellite programs. Each climatology is uniquely formulated to cater to instrument particulars and satellite orbits. The climatologies have general characteristics in common. Dependence on solar activity (determined by F10.7), magnetic activity (determined by Dst), universal time of measurement and magnetic position (invariant latitude and magnetic local time) are common to each climatology. Climatologies for DMSP SSJ/4 instruments, the NOAA-12 Space Environment Monitor Total Energy Detector and Medium Energy Proton and Electron Detector and the LIARS Particle Environment Monitor Medium Energy Particle Spectrometer and High Energy Particle Spectrometer exist separately. Each climatology has strengths and weaknesses in space and time. In order to combine these climatologies and produce representative particle spectra over a larger parameter space, they must be cross-calibrated. We have examined selected spectra from different locations of common climatology parameter space to compare and contrast the differences against LIARS climatology since it covers all magnetic local times in the auroral zone. Overall, climatologies agree for DMSP to within statistical error at dawn and dusk where count statistics are the largest. DMSP climatologies deviate from the LIARS climatology above 2 keV on the night side and below 1 keV on the dayside. The climatology from NOAA agrees with LIARS below 4 keV. Between 30 keV and 100 keV in the southern hemisphere and greater than 30 keV in the northern hemisphere, NOAA and LIARS climatologies differ.

Neural network prediction of relativistic electrons at geosynchronous orbit during the storm recovery phase: effects of recurring substorms

Abstract. During the recovery phase of geomagnetic storms, the flux of relativistic (&gt;2 MeV) electrons at geosynchronous orbits is enhanced. This enhancement reaches a level that can cause devastating damage to instruments on satellites. To predict these temporal variations, we have developed neural network models that predict the flux for the period 1–12 h ahead. The electron-flux data obtained during storms, from the Space Environment Monitor on board a Geostationary Meteorological Satellite, were used to construct the model. Various combinations of the input parameters AL, SAL, Dst and SDst were tested (where S denotes the summation from the time of the minimum Dst). It was found that the model, including SAL as one of the input parameters, can provide some measure of relativistic electron-flux prediction at geosynchronous orbit during the recovery phase. We suggest from this result that the relativistic electron-flux enhancement during the recovery phase is associated with recurring substorms after Dst minimum and their accumulation effect.Key words. Magnetospheric physics (energetic particles, trapped; magnetospheric configuration and dynamics; storms and substorms)

A case history of solar and galactic space weather effects on the geosynchronous communications satellite TDRS-1

Energetic particles of both galactic and solar origin have the potential to cause state changes in memory devices used on-board spacecraft. The particular memory device used in the attitude control system of the Tracking and Data Relay System (TDRS-1) lends itself to the study of this phenomena due to its high susceptibility to such upsets. An eight-year record of TDRS-1 on-orbit upsets reflect the solar cycle variation in galactic radiation as well as radiation enhancements due to solar events. The proton and alpha particle data from the GOES space environment monitor are used to illustrate the radiation environment responsible for these upsets.

SPIDR on the Web: Space Physics Interactive Data Resource on‐line analysis tool

The National Geophysical Data Center's innovative Space Physics Interactive Data Resource (SPIDR) is a multidisciplinary on‐line system to search, browse, and access space weather and environmental data sets over the Internet. SPIDR is a tool for the online user to select data or imagery by date and geographical location and deliver an image to the user over the World Wide Web. Currently, Defense Meteorological Satellite Program (DMSP) satellite imagery, geomagnetic variations, ionospheric vertical incidence databases, and NOAA Goestationary Operational Environmental Satellites (GOES) space environment monitor data can be accessed by SPIDR. DMSP visible, infrared, and microwave imagery displays aurora, city lights, fires, lightning strikes, and cloud coverage. Ionospheric and geomagnetic data, as well as GOES X ray, energetic particle, and the magnetic field at the spacecraft, can be plotted from interactive menus. Solar and geomagnetic indices can be generated as plots for comparison. The Web user selects the month and year from pull‐down menus and clicks the worldwide map in the region of interest. Worldwide contour maps of maximum electron density can also be generated from a global model of the ionosphere.