The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical application.Assessing the credibility of G...The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical application.Assessing the credibility of GIM products in data-sparse regions is of paramount importance.In this study,measurements from the Crustal Movement Observation Network of China(CMONOC)are leveraged to evaluate the suitability of IGS-GIM products over China region in 2013-2014.The indices of mean error(ME),root mean square error(RMSE),and normalized RMSE(NRMSE)are then utilized to quantify the accuracy of IGS-GIM products.Results revealed distinct local time and latitudinal dependencies in IGS-GIM errors,with substantially high errors at nighttime(NRMSE:39%)and above 40°latitude(NRMSE:49%).Seasonal differences also emerged,with larger equinoctial deviations(NRMSE:33.5%)compared with summer(20%).A preliminary analysis implied that the irregular assimilation of sparse IGS observations,compounded by China’s distinct geomagnetic topology,may manifest as error variations.These results suggest that modeling based solely on IGS-GIM observations engenders inadequate representations across China and that a thorough examination would proffer the necessary foundation for advancing regional total electron content(TEC)constructions.展开更多
There are many long-term and short-term prediction methods of Total Electron Content(TEC) that need to be tested for each specific region. Recently, much attention has been paid to testing TEC models in high-, low-lat...There are many long-term and short-term prediction methods of Total Electron Content(TEC) that need to be tested for each specific region. Recently, much attention has been paid to testing TEC models in high-, low-latitude and equatorial regions. This paper compares the TEC prediction methods in the midlatitude zone according to the data of the Juliusruh, Rostov, Manzhouli stations in 2008 and 2015. For a long-term prediction, the IRI-Plas and Ne Quick models are compared with the Global Ionospheric Maps(GIM) presented by the Jet Propulsion Laboratory(JPL) and the Technical University of Catalonia(UPC).For a short-term prediction, the Standard Persistence Model(SPM) method, a 27 day median model, and the proposed short-term prediction method are compared for one day ahead. It is shown that for all stations the IRI-Plas model provides better compliance with GIM maps than the Ne Quick model irrespective of a solar activity level. An average absolute error lays in the range of 3 e3.5 TECU, relative root square mean(RMS) error in the range of 22 e27% in 2015 and 1.7 e2 TECU, 20 e25% in 2008. For the Ne Quick model, these estimates were 6.7 e8.2 TECU and 42 e45% in 2015 and 2.2 e3.6 TECU, 30 e37% in2008. For the short-term forecast, the best results were obtained by the SPM method with an average absolute error in the range of 1.95 e2.15 TECU in 2015 and 0.59 e0.98 TECU in 2008, a relative RMS error in the range of 17 e21% in 2015, 11.5 e15% in 2008. For the proposed short-term prediction method, these errors were 2.04 e2.2 TECU and 12 e14% in 2015 and 0.7 e1.0 TECU, 7 e11% in 2008. Using medians, the errors were 3.1 e3.4 TECU and 17 e21% in 2015 and 1.0 e1.3 TECU, 10 e15% in 2008. The dependence of results on the Dst-index was obtained.展开更多
The responses of Equatorial Ionosphere Anomaly(EIA) to the storm occurred on 17 March 2015 were studied using Global Ionosphere Map(GIM). The variations of Total Electron Content(TEC), latitudinal TEC gradients ...The responses of Equatorial Ionosphere Anomaly(EIA) to the storm occurred on 17 March 2015 were studied using Global Ionosphere Map(GIM). The variations of Total Electron Content(TEC), latitudinal TEC gradients and the rate of latitudinal TEC gradients in EIA regions were investigated in 75?E, 110?E and-60?E longitudinal sectors. The results from the GIM data showed that the distributions of the latitudinal gradient of TEC became monotonous in three longitudes on 18 March(the first day of the recovery phase), but the variations were different. On 18 March, the magnitudes of latitudinal gradients decreased in spatial and temporal in 75?E and 110?E, which means the EIA was suppressed during the recovery phase of the storm, especially in 110?E. The magnitudes of latitudinal TEC gradients showed an obvious increase in spatial and temporal in-60?E. The SAMI2 reproduced the suppression of EIA with a disturbance dynamo electric field, which indicated that the physical process controlled the behaviors of the plasma during the recovery phase of the storm.展开更多
在日固坐标系(地磁纬度和地方时)下,累积地方时过去24 h的COSMIC(Constellation Observing System for Meteorology Ionosphere and Climate)观测资料,通过对110~750 km高度范围内的电子密度进行数值积分得到各掩星点的垂直TEC值,进而...在日固坐标系(地磁纬度和地方时)下,累积地方时过去24 h的COSMIC(Constellation Observing System for Meteorology Ionosphere and Climate)观测资料,通过对110~750 km高度范围内的电子密度进行数值积分得到各掩星点的垂直TEC值,进而利用Kriging方法插值产生近实时的全球地方时MAGLat 2.5°×2 h的COSMIC TEC图.利用2008年1月1日至2010年6月30日共30个月的COSMIC数据,逐日构建COSMIC TEC图,将其与全球导航卫星系统服务组织(International GNSS Service,IGS)发布的全球电离层TEC图(Global Ionospheric Maps,GIMs)以及OSTM/JASON-2卫星高度计观测值分别进行比对,证明利用COSMIC掩星资料构建全球电离层垂直TEC图是可行的.展开更多
基金the National Key R&D Program of China(Grant No.2022YFF0503702)the National Natural Science Foundation of China(Grant Nos.42074186,41831071,42004136,and 42274195)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20211036)the Specialized Research Fund for State Key Laboratories,and the University of Science and Technology of China Research Funds of the Double First-Class Initiative(Grant No.YD2080002013).
文摘The global ionosphere maps(GIM)provided by the International GNSS Service(IGS)are extensively utilized for ionospheric morphology monitoring,scientific research,and practical application.Assessing the credibility of GIM products in data-sparse regions is of paramount importance.In this study,measurements from the Crustal Movement Observation Network of China(CMONOC)are leveraged to evaluate the suitability of IGS-GIM products over China region in 2013-2014.The indices of mean error(ME),root mean square error(RMSE),and normalized RMSE(NRMSE)are then utilized to quantify the accuracy of IGS-GIM products.Results revealed distinct local time and latitudinal dependencies in IGS-GIM errors,with substantially high errors at nighttime(NRMSE:39%)and above 40°latitude(NRMSE:49%).Seasonal differences also emerged,with larger equinoctial deviations(NRMSE:33.5%)compared with summer(20%).A preliminary analysis implied that the irregular assimilation of sparse IGS observations,compounded by China’s distinct geomagnetic topology,may manifest as error variations.These results suggest that modeling based solely on IGS-GIM observations engenders inadequate representations across China and that a thorough examination would proffer the necessary foundation for advancing regional total electron content(TEC)constructions.
文摘There are many long-term and short-term prediction methods of Total Electron Content(TEC) that need to be tested for each specific region. Recently, much attention has been paid to testing TEC models in high-, low-latitude and equatorial regions. This paper compares the TEC prediction methods in the midlatitude zone according to the data of the Juliusruh, Rostov, Manzhouli stations in 2008 and 2015. For a long-term prediction, the IRI-Plas and Ne Quick models are compared with the Global Ionospheric Maps(GIM) presented by the Jet Propulsion Laboratory(JPL) and the Technical University of Catalonia(UPC).For a short-term prediction, the Standard Persistence Model(SPM) method, a 27 day median model, and the proposed short-term prediction method are compared for one day ahead. It is shown that for all stations the IRI-Plas model provides better compliance with GIM maps than the Ne Quick model irrespective of a solar activity level. An average absolute error lays in the range of 3 e3.5 TECU, relative root square mean(RMS) error in the range of 22 e27% in 2015 and 1.7 e2 TECU, 20 e25% in 2008. For the Ne Quick model, these estimates were 6.7 e8.2 TECU and 42 e45% in 2015 and 2.2 e3.6 TECU, 30 e37% in2008. For the short-term forecast, the best results were obtained by the SPM method with an average absolute error in the range of 1.95 e2.15 TECU in 2015 and 0.59 e0.98 TECU in 2008, a relative RMS error in the range of 17 e21% in 2015, 11.5 e15% in 2008. For the proposed short-term prediction method, these errors were 2.04 e2.2 TECU and 12 e14% in 2015 and 0.7 e1.0 TECU, 7 e11% in 2008. Using medians, the errors were 3.1 e3.4 TECU and 17 e21% in 2015 and 1.0 e1.3 TECU, 10 e15% in 2008. The dependence of results on the Dst-index was obtained.
基金Supported by the National Natural Science Foundation of China(41474134,41474135)
文摘The responses of Equatorial Ionosphere Anomaly(EIA) to the storm occurred on 17 March 2015 were studied using Global Ionosphere Map(GIM). The variations of Total Electron Content(TEC), latitudinal TEC gradients and the rate of latitudinal TEC gradients in EIA regions were investigated in 75?E, 110?E and-60?E longitudinal sectors. The results from the GIM data showed that the distributions of the latitudinal gradient of TEC became monotonous in three longitudes on 18 March(the first day of the recovery phase), but the variations were different. On 18 March, the magnitudes of latitudinal gradients decreased in spatial and temporal in 75?E and 110?E, which means the EIA was suppressed during the recovery phase of the storm, especially in 110?E. The magnitudes of latitudinal TEC gradients showed an obvious increase in spatial and temporal in-60?E. The SAMI2 reproduced the suppression of EIA with a disturbance dynamo electric field, which indicated that the physical process controlled the behaviors of the plasma during the recovery phase of the storm.