Online computation of International Reference Ionosphere Extended to Plasmasphere(IRI-Plas) model for space weather

Ionosphere is the most challenging part of Space Weather with its spatio-temporal variability and dispersive nature. Ionospheric models are very important in reducing positioning error in GNSS system.International Reference Ionosphere(IRI) is an empirical, deterministic and climatic model of ionosphere up to 2000 km in height. Recently, IRI Extended to Plasmasphere(IRI-Plas) model has been developed to extend the interest region of IRI to the GPS orbital height of 20,000 km. Both IRI and IRI-Plas provide ionospheric parameters such as electron density, electron and ion temperatures according to their height profiles. In order to update the model to current ionospheric conditions, IRI-Plas can input F2 layer critical frequency(foF2), maximum ionization height(hmF2), and also Total Electron Content(TEC).Online IRI-Plas is developed for the ionospheric community to run multiple tasks at various locations,dates and times with optional foF2, hmF2 and TEC inputs in a user-friendly manner. In this paper, we are going to present the capabilities of the Online IRI-Plas service and provide some comparisons between IRI-Plas outputs and ionosonde measurements. The comparison between online IRI-Plas foF2 outputs and ionosonde foF2 measurements indicates that the model with TEC input can significantly improve the representation of the current ionospheric state, which is very successful especially in the geomagnetically disturbed days.

The effect of space weather on the ionosphere at the 110°meridian during CAWSES-Ⅱperiod

Space weather determines the state of the ionosphere,which is especially important to know during disturbances.To study this state,the period of March 7-17,2012,which was recommended by SCOSTEP for detailed studies and called CAWSES-II,was selected.In this period,the behavior of parameters of the solar wind(SW)and the interplanetary magnetic field(IMF)show a number of features.In this paper,we study their relationship with the total electron content(TEC)and the critical frequency(foF2)of the ionosphere at the 110°meridian,near which several ionosondes are located,in the range of 20°N-62.5°N.The correlation coefficients of TEC and foF2 with the SW and IMF parameters for the month and the selected period are calculated.The ionosphere showed the considered disturbances in different ways in different latitudinal zones:negative anomalies are observed at high latitudes,and positive ones at low latitudes.A distinctive feature is the presence of signs of a super-fountain effect.Deviations of TEC and foF2 from their medians can be significant.The IRI model reacted in the latitude range 40°N-62.5°N in the form of negative anomalies,although positive anomalies were observed in the TEC.At lower latitudes,no reaction was observed.For all factors(F10.7,Dst,Kp,IMF,Np),three zones(high-latitude,midlatitude,and low-latitude)are distinguished for different coefficients.The strongest influence of disturbances on the correlation coefficients is observed in the zone of 37.5°N 62.5°N.

基于ROTI和AATR的测地型GNSS接收机监测北半球高纬度区域电离层闪烁准确性分析

当前,第25个太阳周期已进入强活跃时期,能引发大量电离层不规则体,进而对使得穿行其中的GNSS信号产生电离层闪烁。这已成为影响GNSS全球稳定导航定位服务的重要干扰源。对全球电离层闪烁进行广泛且全面的监测是消除闪烁对GNSS干扰的重要前提,然而传统电离层闪烁监测接收机(ISMR)分布有限,无法满足闪烁全球监测需求;测地型接收机分布广泛,但从其低采样数据中提取的闪烁因子缺乏新太阳周期长时序监测数据验证,导致其闪烁监测可靠性存疑。为此,本文基于近3 a新太阳周期测地型接收机数据,以ISMR提供的闪烁因子为参考,从代表性空间天气事件闪烁响应、日闪烁发生率、闪烁持续时间概率分布、闪烁日发生规律及其随极昼、极夜、地磁指数的特征变化等方面,对比研究了两种测地型接收机电离层闪烁因子(即电离层总电子含量变化率指数ROTI和沿弧段电子含量变化率指数AATR)监测北极高纬度区域电离层闪烁的准确性,并给出了ROTI和AATR在高纬度区域判断闪烁发生的经验阈值。结果表明,ROTI和AATR均能较为准确探测到地磁扰动、太阳活动等因素驱动的区域电离层闪烁,并能有效表征电离层闪烁统计学上的日变化规律,但两种闪烁因子不能准确区分闪烁和电离层电子密度梯度变化,导致在电子密度梯度变化剧烈期间存在较高虚警。该研究成果可为准确选择区域电离层闪烁监测因子提供指导。

GNSS空间环境学研究进展和展望

对流层和电离层是地球近地空间环境中两个重要的组成部分,是靠近地球表面且与人类生活联系最密切的大气圈层。全球导航卫星系统技术的快速发展,为GNSS空间环境学的研究提供了良好的契机。本文介绍了现有GNSS空间环境学中在对流层和电离层方面的研究现状和进展。在GNSS对流层研究方面,主要集中于GNSS对流层关键参数建模和水汽反演两部分;在GNSS电离层研究方面,主要包括GNSS二维/三维电离层建模和区域/全球电离层监测。

空间站和GNSS共视的差别及精度对比分析

为了对比空间站和导航卫星共视的性能差异,深入分析影响共视性能的主要误差源特征,推进共视技术进一步发展,以对共视时间比对基本原理的分析为基础,从系统设计和关键误差源影响两个方面对比分析空间站和导航卫星共视的差异。理论研究结果表明,不同于导航卫星共视,轨道误差是影响空间站共视精度进一步提升的主要因素;此外,空间站共视还需考虑地球引力时延等精细误差的影响。最后,设计并实施了仿真实验和实测实验,通过实验数据进一步对比两者的性能差异。实验结果表明空间站和导航卫星共视各有利弊,虽然空间站共视的服务区域和连续性逊于导航卫星共视,但可以实现的共视精度至少比导航卫星高一个数量级。

Ionospheric Investigations Conducted by Chinese Mainland Scientists in 2020-2021

In this report,we outline works done by scientists from the Mainland of China on various ionospheric topics after the release of the National Report of China in 2020 on ionospheric researchto the Committee on Space Research(COSPAR).More than 170 papers were published in 2020-2021.The current report covers the following topics:ionospheric space weather,ionospheric structures and climatology,ionospheric dynamics and couplings,ionospheric irregularity and scintillation,modeling and data assimilation,and ionosphere and sounding techniques.Planetary ionospheres are included for the first time.

A measure of ionospheric irregularities:zonal velocity and its implications for L-band scintillation at low-latitudes

We estimate the zonal drift velocity of small-scale ionospheric irregularities at low latitude by leveraging the spaced-receivers technique applied to two GNSS receivers for scintillation monitoring installed along the magnetic parallel passing in Presidente Prudente(Brazil,magnetic latitude 12.8°S).The investigated ionospheric sector is ideal to study small-scale irregularities,being located close to the expected position of the southern crest of the equatorial ionospheric anomaly.The measurement campaign took place between September 2013 and February 2014,i.e.equinox and summer solstice seasons under solar maximum,during which the probability of formation of small-scale irregularities is expected to maximize.We found that the hourly average of the velocity increases up to 135 m/s right after the local sunset at ionospheric altitudes and then smoothly decreases in the next hours.Such measurements are in agreement with independent estimations of the velocity made by the Incoherent Scatter Radar located at the Jicamarca Radio Observatory(magnetic latitude 0.1°N),by the Boa Vista Ionosonde(magnetic latitude 12.0°N),and by applying a recently-developed empirical regional short-term forecasting model.Additionally,we investigated the relationship with the percentage occurrence of amplitude scintillation;we report that it is exponentially dependent on the zonal velocity of the irregularities that cause it.

Recent ionospheric investigations in China(2018–2019)

Since the release of the 2018 National Report of China on ionospheric research(Liu LB and Wan WX,2018)to the Committee on Space Research(COSPAR),scientists from China's Mainland have made many new fruitful investigations of various ionospheric-related issues.In this update report,we briefly introduce more than 130 recent reports(2018–2019).The current report covers the following topics:ionospheric space weather,ionospheric structures and climatology,ionospheric dynamics and couplings,ionospheric irregularity and scintillation,modeling and data assimilation,and radio wave propagation in the ionosphere and sounding techniques.

Chinese ionospheric investigations in 2016–2017

After the release of the previous report to the Committee on Space Research(COSPAR) on progress achieved by Chinese scientists in ionospheric researches(Liu LB and Wan WX, 2016), in the recent two years(2016–2017) many interesting new investigations into various ionospheric related issues have been completed. In this report, about 100 publications are summarized. The topics highlighted are as follows: Ionospheric space weather, ionospheric dynamics, ionospheric climatology and modelling, ionospheric irregularity and scintillation, Global Navigation Satellite System(GNSS) related ionospheric issues and other techniques, and radio wave propagation in the ionosphere. An outstanding feature is that more and more observations from the Meridional Project supported the ionospheric investigations.

A Review of the Ionospheric Investigations in China:Progress During 2008-2010

In the ionospheric research,various progresses have been made during the last two years.This paper reviews the recent works of Chinese scientists.For convenience,the contents include:ionospheric storms and space weather;ionospheric irregularities and scintillation;ionospheric variability;ionospheric disturbances;ionospheric response to solar eclipses;ionospheric coupling with atmosphere and lithosphere;ionospheric climatology;ionospheric modeling;and ionospheric prediction and application.

A Review on the Ionospheric Research:Chinese Works During 2006—2008

This paper reviews various progresses on the ionospheric studies by the scientists in China during the last two years.The main contents concern the 4 aspects of the ionospheric re-search:(1) ionospheric weather and coupling with magnetosphere(polar and auroral ionosphere,ionospheric response to substorms,ionospheric storms);(2) mid-and low-latitude ionospheric clima-tology(ionospheric properties,yearly variations and solar activity dependence,long term variation);(3) ionospheric coupling with neutral atmosphere(gravity waves,tides,planetary waves,background upper atmosphere,and ionospheric response);and(4) ionospheric diagnostics(observation,modeling,and prediction).

Cost-Efficient Medium Frequency Propagation Research with Software Defined Radio

Medium Frequency radio holds significance in modern society as it supports broadcasting and individual communications in the public, government, and military sectors. Enhancing the availability and quality of these communications is only possible by enhancing the understanding of medium frequency propagation. While traditional methods of radio wave propagation research can have a high material demand and cost, software defined radio presents itself as a versatile and low-cost platform for medium frequency signal reception and data acquisition. This paper details a research effort that utilizes software defined radio to help characterize medium frequency signal strength in relation to ionospheric and solar weather propagation determinants. Signal strength data from seven medium frequency stations of unique transmission locations and varying transmission powers were retrieved in 24-hour segments via a receiving loop antenna, Airspy HF+ Discovery software defined radio, and SDR Sharp software interface network. Retrieved data sets were visualized and analyzed in MATLAB for the identification of signal strength trends, which were subsequently compared to historical ionospheric and space weather indices in pursuit of a quantifiable correlation between such indices and medium frequency signal strengths. The results of the investigation prove that software defined radio, when used in conjunction with a receiving antenna and data analysis program, provides a versatile mechanism for cost-efficient propagation research.

Mapping of ionospheric parameters for space weather predictions: A concise review

Reviewing briefly the recent progress in a joint program of specifying the polar ionosphere primarily on the basis of ground magnetometer data, this paper em-phasizes the importance of processing data from around the world in real time for space weather predictions. The output parameters from the program include ionospheric electric fields and currents and field-aligned currents. These real-time records are essential for running computer simulations under realistic boundary conditions and thus for making numerical predictions of space weather efficient as reliable as possible. Data from individual ground magnetometers as well as from the solar wind are collected and are used as input for the KRM and AMIE mag-netogram-inversion algorithms, through which the two-dimensional distribution of the ionospheric parameters is calculated. One of the goals of the program is to specify the solar-terrestrial environment in terms of ionospheric processes and to provide the scientific community with more than what geomagnetic activity indices and statistical models indicate.

我国空间物理研究进展

经过多年的建设与努力,我国日地空间物理与空间天气领域的研究呈现蓬勃的发展态势.《地球物理学报》以空间物理为专辑,集中在2014年11期刊发38篇文章,涵盖了基于"子午工程"观测数据分析在内的空间物理和空间天气方面的一批最新研究成果.这些工作涉及电离层、中高层大气、地磁与磁层、太阳及太阳风等学科方向,还有两篇工作涉及行星空间环境.本文将从这五个学科方向简要地介绍收入专辑的这些工作.

空间天气研究进展

空间天气对人类活动具有深刻的影响,关系到社会的经济发展和国家安全,其研究和应用正面临着日益增长的需求。主要从业务和应用的角度,描述了空间天气所涉及的主要区域内的空间天气现象及空间天气要素近年来国内外的主要研究进展和态势,以期读者对空间天气有一个整体的认识。

Recent progress in Chinese polar upper-atmospheric physics research: review of research advances supported by the Chinese Arctic and Antarctic expeditions

It has been more than 30 years since the first Chinese Antarctic Expedition took place. Polar upper atmospheric observations started at this time. First began at Great Wall Station and then at Zhongshan Station in Antarctica, and later in the Arctic at Yellow River Station, Kjell Henriksen Observatory on Svalbard, and at the China-Iceland Joint Aurora Observatory in Iceland. In this paper, we reviewed the advances in polar upper atmosphere physics （UAP） based on the Chinese national Arctic and Antarctic research over the last five years. These included newly deployed observatories and research instruments in the Arctic and Antarctic; and new research findings, from grotmd-based observations, about polar ionosphere dynamics, aurora and particle precipitation, polar plasma convection, geomagnetic pulsations and space plasma waves, space weather in the polar regions, simulations of the polar ionosphere-magnetosphere. In conclusion, suggestions were made for future polar upper atmosphere physics research in China.

空间天气对导航卫星的影响

简要介绍了空间天气的基本概念,对灾害性空间天气可能对导航卫星所产生的主要影响进行了探索;进而着重分析了电离层电子密度、电离层暴、电离层突然骚扰等空间天气要素对卫星导航定位系统的影响。

基于陆态网络GPS数据的电离层空间天气监测与研究

中国大陆构造环境监测网络(简称陆态网络)是以全球卫星导航定位系统(GNSS)为主,辅以多种空间观测技术,实时动态监测大陆构造环境变化,探求其对资源、环境和灾害的影响的地球科学综合观测网络.基于陆态网络约200个基准站的GPS观测数据,本文探讨了其在电离层空间天气监测与研究方面的应用.包括磁暴期间电离层暴扰动形态,大尺度电离层行进式扰动,太阳耀斑引起的电离层骚扰和低纬电离层不规则体结构等.研究结果表明:陆态网络布局合理,观测数据质量良好,完全可用于中国及周边地区电离层空间天气监测与研究,为进一步开展我国电离层空间天气预警和预报奠定了观测基础.

空间天气对水面舰艇卫星导航定位的影响

简要介绍空间天气和电离层基本概念,对灾害性空间天气可能对导航卫星和电离层所产生的主要影响进行有意义的探索;进而着重对电离层电子密度、电离层暴、电离层突然骚扰等空间天气要素会对水面舰艇卫星导航定位系统的影响。

“风云三号”D星电离层光度计

“风云三号”D星电离层光度计(IPM)是我国首次利用天基方式对电离层进行全天候定量化光学遥感观测的载荷。该载荷通过观测电离层夜/日间OI 135.6 nm气辉辐射强度、日间N2LBH带气辉辐射强度,可以反演获取夜间电子总含量(TEC)、F2层峰值电子密度(NmF2)及日间O/N2比等关键电离层环境信息。该载荷具备夜间高灵敏度观测的突出优势,非常适合电离层精细结构和微小变化观测,配置了夜间和日间两种工作模式,可以实现对电离层关键环境信息的全天候监测。文章主要对该电离层光度计的观测目标、观测原理、系统组成和在轨观测结果进行介绍。