China's COMPASS satellite navigation system relies on a regional tracking network to provide navigation services.Limited by its geographic border,the regional network is able to cover only 30%of the medium-earth-o...China's COMPASS satellite navigation system relies on a regional tracking network to provide navigation services.Limited by its geographic border,the regional network is able to cover only 30%of the medium-earth-orbits(MEO).Accuracy of determined and predicted orbits is not able to satisfy system requirements if the tracking data processing strategy for global tracking network processing is used for the regional network.Two major error sources for orbital prediction are accuracy of initial orbital elements and dynamical modeling.To achieve better prediction accuracy,we propose a two-step orbit determination and prediction strategy.For step 1,only solar radiation pressure(SRP)parameters are estimated along with the orbital elements and other parameters;for step 2,all parameters are estimated but the SRP parameters are tightly constrained to their step 1 estimates.Experimenting with data from a regional GPS network,we conclude for orbital prediction using the proposed two-step strategy,the average user range error(URE)for 24-h prediction arcs is better than 0.6 m.展开更多
The paper shows the statistical analysis of cyclone tracks that have influence on the western Antarctic region.Based on the conditions of cyclone movement and its impact upon the weather,cyclone tracks are classified ...The paper shows the statistical analysis of cyclone tracks that have influence on the western Antarctic region.Based on the conditions of cyclone movement and its impact upon the weather,cyclone tracks are classified into three categories,i.e.,the track moving towards the northern tip of the Antarctic Peninsula, southern track,and northern track. Moreover,in this paper,the frequency distributions of cyclone tracks,the major tracks with higher frequencies,the original region of Antarctic cyclones and the seasonal features of Antarctic cyclones have been analyzed.The results show that there are higher cyclogeneses in summer,whereas relatively fewer cycloge- neses in winter,and cyclone numbers in transitional seasons are close to the climatological average.The analysis also shows that the moving velocity of Antarctic cyclone is about the same in winter and summer. It obviously speed up during the transitional season.展开更多
Experiments and analyses are carried out for GEO and joint GEO/IGSO precise orbit determination using data recorded by China's regional tracking network.Results show that joint GEO/IGSO orbit determination effecti...Experiments and analyses are carried out for GEO and joint GEO/IGSO precise orbit determination using data recorded by China's regional tracking network.Results show that joint GEO/IGSO orbit determination effectively solves the problem of poor observation geometry for GEO satellites.The laser radial evaluation thus confirms that precision is as good as less than 0.1 m.In the case of joint orbit determination,solving the empirical acceleration can reduce errors introduced by the imprecise solar radiation pressure model used for Chinese satellites.This method also improves the accuracy of orbit prediction in the radial direction.The ephemeris accuracy is thus improved and the ephemeris can provide a better service to users with navigation and positioning requirements.展开更多
基金was supported by the National High Technology Research and Development Program of China(Grant No.2007AA12Z345)the Science and Technology Commission of Shanghai Municipality of China(Grant No.06DZ22101)
文摘China's COMPASS satellite navigation system relies on a regional tracking network to provide navigation services.Limited by its geographic border,the regional network is able to cover only 30%of the medium-earth-orbits(MEO).Accuracy of determined and predicted orbits is not able to satisfy system requirements if the tracking data processing strategy for global tracking network processing is used for the regional network.Two major error sources for orbital prediction are accuracy of initial orbital elements and dynamical modeling.To achieve better prediction accuracy,we propose a two-step orbit determination and prediction strategy.For step 1,only solar radiation pressure(SRP)parameters are estimated along with the orbital elements and other parameters;for step 2,all parameters are estimated but the SRP parameters are tightly constrained to their step 1 estimates.Experimenting with data from a regional GPS network,we conclude for orbital prediction using the proposed two-step strategy,the average user range error(URE)for 24-h prediction arcs is better than 0.6 m.
文摘The paper shows the statistical analysis of cyclone tracks that have influence on the western Antarctic region.Based on the conditions of cyclone movement and its impact upon the weather,cyclone tracks are classified into three categories,i.e.,the track moving towards the northern tip of the Antarctic Peninsula, southern track,and northern track. Moreover,in this paper,the frequency distributions of cyclone tracks,the major tracks with higher frequencies,the original region of Antarctic cyclones and the seasonal features of Antarctic cyclones have been analyzed.The results show that there are higher cyclogeneses in summer,whereas relatively fewer cycloge- neses in winter,and cyclone numbers in transitional seasons are close to the climatological average.The analysis also shows that the moving velocity of Antarctic cyclone is about the same in winter and summer. It obviously speed up during the transitional season.
基金supported by the National Natural Science Foundation of China (Grant No.41074020)
文摘Experiments and analyses are carried out for GEO and joint GEO/IGSO precise orbit determination using data recorded by China's regional tracking network.Results show that joint GEO/IGSO orbit determination effectively solves the problem of poor observation geometry for GEO satellites.The laser radial evaluation thus confirms that precision is as good as less than 0.1 m.In the case of joint orbit determination,solving the empirical acceleration can reduce errors introduced by the imprecise solar radiation pressure model used for Chinese satellites.This method also improves the accuracy of orbit prediction in the radial direction.The ephemeris accuracy is thus improved and the ephemeris can provide a better service to users with navigation and positioning requirements.
