Changyong He

Changyong He
Hunan University of Science and Technology · Laboratory of Geo-spatial Information Technology

PhD

About

27
Publications
6,548
Reads
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211
Citations
Additional affiliations
September 2019 - present
Institut national de l’information géographique et forestière
Position
  • PostDoc Position
Education
July 2015 - August 2019
RMIT University
Field of study
  • Aerodynamics and Thermosphere
September 2011 - June 2013
Wuhan University
Field of study
  • GNSS navigation and positioning
September 2007 - June 2011
Wuhan University
Field of study
  • GNSS meteorology

Publications

Publications (27)
Article
The three-dimensional reconstruction of a tilt series for ionospheric tomography is commonly carried out using one of iterative algorithms such as the simultaneous iteration reconstruction technique (SIRT). This reconstruction algorithm cannot do the high computation efficiency and reconstruction accuracy is low. Here, we develop an adaptive simult...
Article
Full-text available
Troposphere delay is one of the main error sources in global navigation satellite systems (GNSS). Its obvious randomness is mainly attributed to meteorological parameters (total pressure, temperature and water vapor pressure, etc.). In this paper, the temporal and spatial variations of global Zenith Troposphere Delay (ZTD) is analyzed using the tim...
Article
Tropospheric delay acts as a systematic error source in the Global Navigation Satellite Systems (GNSS) positioning. Empirical models UNB3, UNB3m, UNB4 and EGNOS have been developed for use in Satellite-Based Augmentation Systems (SBAS). Model performance, however, is limited due to the low spatial resolution of the look-up tables for meteorological...
Conference Paper
Full-text available
The atmospheric weighted mean temperature Tm plays a pivotal role in remote sensing water vapor with GNSS technique. However, real-time Tm cannot be obtained at given place due to limitation of modern technology. In order to remove this barrier, a global and season-specific T m model (GWMT-I) based on spherical harmonics analysis was built using la...
Article
Full-text available
Surface pressure is a vital meteorological variable for the accurate determination of precipitable water vapor (PWV) using Global Navigation Satellite Systems (GNSS). The lack of pressure observations is a big issue for the study of climate using historical GNSS observations, which is a relatively new area of GNSS applications in climatology. Hence...
Article
Full-text available
Geomagnetic storms on 7–8 September 2017 triggered severe ionospheric disturbances that had a serious effect on satellite navigation and radio communication. Multiple observations derived from Global Navigation Satellite System receivers, Earth's Magnetic Field and Environment Explorers (SWARM) and the Thermosphere‐Ionosphere ‐Electrodynamics Gener...
Article
Full-text available
This paper presents a tool for the numerical propagation of high-fidelity astrodynamics, called PHiFA. The coupled orbit—attitude dynamics for space objects are modeled by considering various types of perturbative forces and torques. Two methods have been implemented to calculate the surface forces: the area matrix method and the beam method. The b...
Article
Full-text available
Atmospheric mass density (AMD) plays a vital role in the drag calculation for space objects in low Earth orbit. Many empirical AMD models have been developed and used for orbit prediction and efforts continue to improve their accuracy in forecasting high-altitude atmospheric conditions. Previous studies have assessed these models at the height of 2...
Article
Full-text available
The ionosphere plays an important role in satellite navigation, radio communication, and space weather prediction. However, it is still a challenging mission to develop a model with high predictability that captures the horizontal‐vertical features of ionospheric electrodynamics. In this study, multiple observations during 2005–2019 from space‐born...
Article
Full-text available
There are remarkable ionospheric discrepancies between space-borne (COSMIC) measurements and ground-based (ionosonde) observations, the discrepancies could decrease the accuracies of the ionospheric model developed by multi-source data seriously. To reduce the discrepancies between two observational systems, the peak frequency (foF2) and peak heigh...
Article
Full-text available
The space object catalog provides orbital state and characteristic information of space objects for critical applications in space situational awareness. Maintaining accurate states for all objects in the catalog is essential, but it leads to large loads on sensors and limits the time available to search for new objects. This study proposes a novel...
Preprint
Full-text available
The ionospheric delay is of paramount importance to radio communication, satellite navigation and positioning. It is necessary to predict high-accuracy ionospheric peak parameters for single frequency receivers. In this study, the state-of-the-art artificial neural network (ANN) technique optimized by the genetic algorithm is used to develop global...
Preprint
Key Points: A new empirical atmospheric mass density model has been developed with a focus on the ion contribution. A new data source of COSMIC ephemerides has been used to assess the atmospheric mass density performance in orbit prediction, reducing bias. The new atmospheric mass density model outperforms all other state-of-the-art models during t...
Article
Full-text available
Many thermospheric mass density (TMD) variations have been recognized in observations and physical simulations, however, their impact on the low‐Earth‐orbit (LEO) satellites has not been fully evaluated. The present study investigates the quantitative impact of periodic spatiotemporal TMD variations modulated by the empirical DTM2013 model. Also co...
Article
Full-text available
Two solar flares X2.2 and X9.3 erupted over the active region 2673 on 6 September 2017, and the second flare is the strongest since 2005. In order to investigate the ionospheric and thermospheric responses to the two solar flares, the global total electron content and the critical frequency of F2 layer obtained from GPS stations and ionosondes are...
Article
Full-text available
Precipitable water vapour (PWV) over a ground station can be estimated from the global navigation satellite systems (GNSS) signal's zenith wet delays (ZWD) multiplying by a conversion factor that is a function of weighted-mean temperature (Tm). The commonly used Bevis Tm model (BTM) may not perform well in some regions due to its use of data from N...
Article
Full-text available
Global Navigation Satellite System (GNSS) radio occultation (RO) has been widely used in the prediction of weather, climate, and space weather, particularly in the area of tropospheric analyses. However, one of the issues with GNSS RO measurements is that they are interfered with by the signals reflected from the earth's surface. Many RO events are...
Article
Full-text available
The Global Positioning System (GPS) is a powerful atmospheric observing system for determining precipitable water vapour (PWV). In the detection of PWV using GPS, the atmospheric weighted mean temperature (Tm) is a crucial parameter for the conversion of zenith tropospheric delay (ZTD) to PWV since the quality of PWV is affected by the accuracy of...
Conference Paper
Full-text available
Without consideration of stochastic forces, orbital dynamical systems are expressed by ordinary differential equations (ODE) andits orbital uncertainty propagation (OUP) can be solved by one of the following methods: Monte Carlo simulations (MCS), statetransition tensors, polynomial chaos expansion, etc. While the stochastic forces or diffusion (e....
Article
Full-text available
In this study, radiosonde observations during the period of 2012-2013 from three stations in the Hunan region, China, were used to establish regional Tm models (RTMs) that are a fitting function of multiple meteorological factors ( Ts , Es , and Ps ). One-factor, two-factor, and three-factor RTMs were assessed by comparing their Tm against the radi...
Article
Full-text available
The Global Positioning System (GPS) has been regarded as a powerful atmospheric observing system for determining precipitable water vapour (PWV) nowadays. One of the most critical variables in PWV remote sensing using GPS technique is the zenith tropospheric delay (ZTD). The conversion from ZTD to PWV requires a good knowledge of the atmospheric-we...
Article
The initial orbital state of a space object cannot be determined using atracklet as the tracklet only contains angular and angular rate observations without any ranging information. One approach to determine confident initial orbits is to constructan admissible region, which restricts the range/range-rate to a compact subset by considering physical...
Article
The 2012 Haida Gwaii earthquake was a massive Mw 7.8 earthquake that struck the Queen Carlotte Islands Region on 28 October 2012 (UTC). This study analyzed the variations in zenith tropospheric delay (ZTD) following the Mw 7.8 Haida Gwaii earthquake using near real-time ZTD data collected from eleven stations in the seismic region and the forecast...
Article
The troposphere delay is one of the major error resources for the accuracy of GPS positioning. Empirical models were unable to provide sufficient accuracy for the precise positioning with increasing demand of precision, the continuously operating reference stations (CORS) built around the world shed lights on constructing more precise tropospheric...

Questions

Question (1)
Question
The tidal displacements of ground-based stations are widely considered in the processing of space geodetic techniques (e.g., SLR and GNSS) for a higher accuracy. One of these tidal displacements is the atmospheric tidal loading (ATL). This loading is usually calculated from the sine and cosine terms of both diurnal S1 and semidiurnal S2 tides. More information can be found in IERS2010 convention and the following reference:
  • Ray, R. D. and R. M. Ponte, 2003, Barometric tides from ECMWF operational analyses, Ann. Geophys., 21(8): 1897–1910, doi:10.5194/angeo-21-1897-2003.
An on-line ATL calculator service is kindly provided by T. M. van Dam at the University of Luxembourg and R. Ray at Space Geodesy Branch, NASA Goddard Space Flight Center (GSFC, https://geophy.uni.lu/atmosphere/tide-loading-calculator/).
A similar tidal displacement product is kindly provided by TU Wien
(https://vmf.geo.tuwien.ac.at/). This atmospheric tidal displacement is called the atmospheric pressure loading (APL), which includes two types: tidal and non-tidal displacement. The detailed reference is given as follows.
  • D.D. Wijaya, J. Böhm, M. Karbon, H. Krasna, and H. Schuh (2013), Atmospheric pressure loading, Chapter 4 in Atmospheric effects in space geodesy, J. Böhm and H. Schuh (eds), Springer-Verlag Berlin Heidelberg.
My question is what is the difference between ATL and APL. I guess the ATL is the tidal displacement in APL. Thanks in advance for your answers.

Projects

Projects (2)
Archived project
Project
Currently, I'm working in the field of Space Situational Awareness(SSA), such as angles-only initial orbit determination (IOD), multi-target tracking (MTT), uncertainty quantification (UQ), etc.