In this work,the daily height variations of SZ-5(Shenzhou-5) cabin from 22 October to 28 November in 2003 are analyzed,which includes the period of the Halloween Storm and the Great November Storm.The significant orbi...In this work,the daily height variations of SZ-5(Shenzhou-5) cabin from 22 October to 28 November in 2003 are analyzed,which includes the period of the Halloween Storm and the Great November Storm.The significant orbital decays have been observed at the end of October and in late November due to the great solar flares and the severe geomagnetic storms.According to the equation of the air-drag-force on a spacecraft and the SZ-5 orbital decay information,the relative daily average thermospheric density changes during the three 2003 super-storms are derived and the results are compared with the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended Model(NRLMSISE-00).The results show that the daily average thermospheric density(at the altitude of SZ-5,about 350 km) in storm time enhances to approximately 200% as much as that in the quiet time but the empirical model may somewhat underestimate the average thermospheric density changes and the daily contributions of geomagnetic storms to the density enhancements during these severe space weather events.展开更多
Low Earth Orbit satellite on-board accelerometers play an important role in improving our understanding of thermosphere density;however,the accelerometer-derived densities are subject to accelerometer calibration erro...Low Earth Orbit satellite on-board accelerometers play an important role in improving our understanding of thermosphere density;however,the accelerometer-derived densities are subject to accelerometer calibration errors.In this study,two different dynamic calibration schemes,the accelerometer parameter-incorporated orbit fitting and precise orbit determination(POD),are investigated with the Gravity Recovery And Climate Experiment(GRACE)satellite accelerometers for thermosphere density derivation during years 2004–2007(inclusive).We show that the GRACE accelerometer parametrization can be optimized by fixing scale coefficients and estimating biases every 60 min so that the orbit fitting and POD precision can be improved from 10 cm to 2 cm in the absence of empirical acceleration compensations and as a result the integrity of calibration parameters may be reserved.The orbit-fitting scheme demonstrates similar calibration precision with respect to POD.Their bias estimates in the along-track and cross-track components exhibit an offset within 0.1%and a standard deviation(STD)less than 0.3%.Correspondingly,a bias of 2.20%and a STD of 5.75%exists between their thermosphere density estimates.The orbit-fitting and POD-derived thermosphere densities are validated through the comparison against the results published by other institution.The comparison shows that either of them can achieve a precision level at 6%.To derive thermosphere density from the rapid-increasing amount of on-board accelerometer data sets,it is suggested to take full advantage of the orbit-fitting scheme due to its high efficiency as well as high precision.展开更多
基金Supported by the Natural Science Foundation of China(41574178,41874187,41774152,41774195)Grant from CAS Key Laboratory of Geospace Environment,University of Science and Technology of China
文摘In this work,the daily height variations of SZ-5(Shenzhou-5) cabin from 22 October to 28 November in 2003 are analyzed,which includes the period of the Halloween Storm and the Great November Storm.The significant orbital decays have been observed at the end of October and in late November due to the great solar flares and the severe geomagnetic storms.According to the equation of the air-drag-force on a spacecraft and the SZ-5 orbital decay information,the relative daily average thermospheric density changes during the three 2003 super-storms are derived and the results are compared with the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended Model(NRLMSISE-00).The results show that the daily average thermospheric density(at the altitude of SZ-5,about 350 km) in storm time enhances to approximately 200% as much as that in the quiet time but the empirical model may somewhat underestimate the average thermospheric density changes and the daily contributions of geomagnetic storms to the density enhancements during these severe space weather events.
基金the National Natural Science Foundation[grant numbers 42004020,42074032,41931075 and 42030109]National Defense Key Laboratory of Aerospace Flight Dynamics technology(grant number 6142210190101)+2 种基金China Postdoctoral Science Foundation[grant number 2021M692460]the Fundamental Research Funds for the Central Universities[grant number 2042021kf0060]Wuhan Science and Technology Bureau[grant number 2019010701011391].
文摘Low Earth Orbit satellite on-board accelerometers play an important role in improving our understanding of thermosphere density;however,the accelerometer-derived densities are subject to accelerometer calibration errors.In this study,two different dynamic calibration schemes,the accelerometer parameter-incorporated orbit fitting and precise orbit determination(POD),are investigated with the Gravity Recovery And Climate Experiment(GRACE)satellite accelerometers for thermosphere density derivation during years 2004–2007(inclusive).We show that the GRACE accelerometer parametrization can be optimized by fixing scale coefficients and estimating biases every 60 min so that the orbit fitting and POD precision can be improved from 10 cm to 2 cm in the absence of empirical acceleration compensations and as a result the integrity of calibration parameters may be reserved.The orbit-fitting scheme demonstrates similar calibration precision with respect to POD.Their bias estimates in the along-track and cross-track components exhibit an offset within 0.1%and a standard deviation(STD)less than 0.3%.Correspondingly,a bias of 2.20%and a STD of 5.75%exists between their thermosphere density estimates.The orbit-fitting and POD-derived thermosphere densities are validated through the comparison against the results published by other institution.The comparison shows that either of them can achieve a precision level at 6%.To derive thermosphere density from the rapid-increasing amount of on-board accelerometer data sets,it is suggested to take full advantage of the orbit-fitting scheme due to its high efficiency as well as high precision.