The ionospheric TEC in the sunlit boundary region during outburst of the great flare on Oct. 28, 2003 is analyzed using GPS data from IGS network. It is found that the ionosphere over the region of solar zenith angle ...The ionospheric TEC in the sunlit boundary region during outburst of the great flare on Oct. 28, 2003 is analyzed using GPS data from IGS network. It is found that the ionosphere over the region of solar zenith angle <105°was affected by this flare radiation, and the TEC enhancement decreased with the solar zenith angle. The results show that the value of TEC enhancement over the region of zenith angle ≈80° was about I0 TECU, at the terminate region (zenith angle≈90°) the TEC enhancement was about 7 TECU, and the TEC enhancement over the region of zenith angle≈110° was 1-2 TECU.展开更多
The hourly values of the ionospheric F2 layer critical frequency, foF2, recorded at Wakkanai ionosonde station （45.4°N, 141.7°E） have been collected to construct a middle-latitude single-station model for ...The hourly values of the ionospheric F2 layer critical frequency, foF2, recorded at Wakkanai ionosonde station （45.4°N, 141.7°E） have been collected to construct a middle-latitude single-station model for forecasting foF2 under geomagnetic quiet and disturbed conditions. The module for the geomagnetic quiet conditions incorporates local time, seasonal, and solar vari- ability of climatological foF2 and its upper and lower quartiles. It is the first attempt to predict the upper and lower quartiles of foF2 to account for the notable day-to-day variability in ionospheric foF2. The validation statistically verifies that the model captures the climatological variations of foF2 with higher accuracy than IRI does. The storm-time module is built to capture the geomagnetic storm induced relative deviations of foF2 from the quiet time references. In the geomagnetically disturbed module, the storm-induced deviations are described by diumal and semidiumal waves, which are modulated by a modified magnetic activity index, the Kf index, reflecting the delayed responses of foF2 to geomagnetic activity forcing. The coeffi- cients of the model in each month are determined by fitting the model formula to the observation in a least-squares way. We provide two options for the geomagnetic disturbed module, including or not including Kalman filter algorithm. The Kalman filter algorithm is introduced to optimize these coefficients in real time. Our results demonstrate that the introduction of the Kalman filter algorithm in the storm time module is promising for improving the accuracy of predication. In addition, comparisons indicate that the IRI model prediction of the F2 layer can be improved to provide better performances over this region.展开更多
文摘The ionospheric TEC in the sunlit boundary region during outburst of the great flare on Oct. 28, 2003 is analyzed using GPS data from IGS network. It is found that the ionosphere over the region of solar zenith angle <105°was affected by this flare radiation, and the TEC enhancement decreased with the solar zenith angle. The results show that the value of TEC enhancement over the region of zenith angle ≈80° was about I0 TECU, at the terminate region (zenith angle≈90°) the TEC enhancement was about 7 TECU, and the TEC enhancement over the region of zenith angle≈110° was 1-2 TECU.
基金supported by the CMA (Grant No. GYHY201106011)the National Basic Research Program of China ("973" Project) (Grant No. 2012CB- 825604)+1 种基金the National Natural Science Foundation of China (Grant Nos. 41074112, 41174137, 41174138)the Specialized Research Fund for State Key Laboratories
文摘The hourly values of the ionospheric F2 layer critical frequency, foF2, recorded at Wakkanai ionosonde station （45.4°N, 141.7°E） have been collected to construct a middle-latitude single-station model for forecasting foF2 under geomagnetic quiet and disturbed conditions. The module for the geomagnetic quiet conditions incorporates local time, seasonal, and solar vari- ability of climatological foF2 and its upper and lower quartiles. It is the first attempt to predict the upper and lower quartiles of foF2 to account for the notable day-to-day variability in ionospheric foF2. The validation statistically verifies that the model captures the climatological variations of foF2 with higher accuracy than IRI does. The storm-time module is built to capture the geomagnetic storm induced relative deviations of foF2 from the quiet time references. In the geomagnetically disturbed module, the storm-induced deviations are described by diumal and semidiumal waves, which are modulated by a modified magnetic activity index, the Kf index, reflecting the delayed responses of foF2 to geomagnetic activity forcing. The coeffi- cients of the model in each month are determined by fitting the model formula to the observation in a least-squares way. We provide two options for the geomagnetic disturbed module, including or not including Kalman filter algorithm. The Kalman filter algorithm is introduced to optimize these coefficients in real time. Our results demonstrate that the introduction of the Kalman filter algorithm in the storm time module is promising for improving the accuracy of predication. In addition, comparisons indicate that the IRI model prediction of the F2 layer can be improved to provide better performances over this region.
