The correlation of flare’s location on solar disc with the value of sudden increase of total electron content is analyzed with flare’s parameters observed by GOES satellite from 1997 to 1999 and total electron conte...The correlation of flare’s location on solar disc with the value of sudden increase of total electron content is analyzed with flare’s parameters observed by GOES satellite from 1997 to 1999 and total electron content derived from GPS data observed by international GPS Service for Geo-dynamics. It is found that, besides the flare’s maximum X-ray flux, flare’s location on solar disc has some relation with the value of SITEC during the flare. The ionospheric response to a flare with a smaller maximum X-ray flux and nearer angular distance to the Sun’s central meridian line may be stronger than that of the flare with a larger maxi-mum X-ray flux and far angular distance. To the flares with the same class of maximum X-ray flux, the nearer the angu-lar distance to the Sun’s meridian, the stronger the ionospheric response.展开更多
The present paper studies the sudden increase in total electron content (SITEC) on the ionosphere caused by the very intense solar flare on July 14, 2000. According to the well-known Chapman theory of ionization, we d...The present paper studies the sudden increase in total electron content (SITEC) on the ionosphere caused by the very intense solar flare on July 14, 2000. According to the well-known Chapman theory of ionization, we derive the relationship between the temporal variation rate, TEC/t, of the total electron content (TEC) and the flare parameters. It is shown that ?TEC/t is proportional to the effective flare radiation flux, I_f, and inversely proportional to the Chapman function, ch(x), of the zenith angle x. TEC data observed by the GPS networks located in China, Southeast Asia and Australia during the very intense solar flare on July 14, 2000 are used to statis- tically investigate the relation between the observed TEC/t and ch(x). The analyses show that the two quantities are inversely proportional to each other, as the theory predicted. The pre- sent work shows that GPS observation is a powerful tool for studying solar flare effects on the ionosphere, i.e. the sudden ionospheric disturbances (SIDs). Because of its advantages of high precision, large geographical distribution and good temporal resolution, GPS TEC observation may reveal quantitatively the process of ionospheric disturbances caused by solar flares. Therefore, our results are of significance in the space weather research.展开更多
Using GPS data obtained from GPS sites located on the sunlit hemisphere during the flare on July 14, 2000, the ionospheric response to the flare was analyzed. A kind of tiny correlative ionospheric fluctuations were r...Using GPS data obtained from GPS sites located on the sunlit hemisphere during the flare on July 14, 2000, the ionospheric response to the flare was analyzed. A kind of tiny correlative ionospheric fluctuations were revealed from the temporal total electron content (TEC) curves derived from GPS measurements, and the values of this kind of disturbances are about 1015 m-2. A comparative analysis of these disturbances and soft X-ray flux detected at GOES satellite during the flare is done. It is found that this kind of disturbances revealed in the temporal TEC curves did occur in a very large area of sunlit ionosphere and its behavior is mainly controlled by the characteristics of the flare’s extra radiation. Because the similar fluctuations are not found in the curve of soft X-ray flux, it is concluded that the flare extra radiation in EUV band should have corresponding fluctuations and it is the fluctuations that cause the TEC disturbances. The height, where the disturbances occur, should be in the F展开更多
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
基金This work was supported by the National Natural Science Foundation of C'hina (Grant Nos. 49874041 and 49990455).
文摘The correlation of flare’s location on solar disc with the value of sudden increase of total electron content is analyzed with flare’s parameters observed by GOES satellite from 1997 to 1999 and total electron content derived from GPS data observed by international GPS Service for Geo-dynamics. It is found that, besides the flare’s maximum X-ray flux, flare’s location on solar disc has some relation with the value of SITEC during the flare. The ionospheric response to a flare with a smaller maximum X-ray flux and nearer angular distance to the Sun’s central meridian line may be stronger than that of the flare with a larger maxi-mum X-ray flux and far angular distance. To the flares with the same class of maximum X-ray flux, the nearer the angu-lar distance to the Sun’s meridian, the stronger the ionospheric response.
基金the National Important Basic Research Project (G2000078407) the National Natural Science Foundation of China (Grant No. 49974039).
文摘The present paper studies the sudden increase in total electron content (SITEC) on the ionosphere caused by the very intense solar flare on July 14, 2000. According to the well-known Chapman theory of ionization, we derive the relationship between the temporal variation rate, TEC/t, of the total electron content (TEC) and the flare parameters. It is shown that ?TEC/t is proportional to the effective flare radiation flux, I_f, and inversely proportional to the Chapman function, ch(x), of the zenith angle x. TEC data observed by the GPS networks located in China, Southeast Asia and Australia during the very intense solar flare on July 14, 2000 are used to statis- tically investigate the relation between the observed TEC/t and ch(x). The analyses show that the two quantities are inversely proportional to each other, as the theory predicted. The pre- sent work shows that GPS observation is a powerful tool for studying solar flare effects on the ionosphere, i.e. the sudden ionospheric disturbances (SIDs). Because of its advantages of high precision, large geographical distribution and good temporal resolution, GPS TEC observation may reveal quantitatively the process of ionospheric disturbances caused by solar flares. Therefore, our results are of significance in the space weather research.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 49874041 and 49990455).
文摘Using GPS data obtained from GPS sites located on the sunlit hemisphere during the flare on July 14, 2000, the ionospheric response to the flare was analyzed. A kind of tiny correlative ionospheric fluctuations were revealed from the temporal total electron content (TEC) curves derived from GPS measurements, and the values of this kind of disturbances are about 1015 m-2. A comparative analysis of these disturbances and soft X-ray flux detected at GOES satellite during the flare is done. It is found that this kind of disturbances revealed in the temporal TEC curves did occur in a very large area of sunlit ionosphere and its behavior is mainly controlled by the characteristics of the flare’s extra radiation. Because the similar fluctuations are not found in the curve of soft X-ray flux, it is concluded that the flare extra radiation in EUV band should have corresponding fluctuations and it is the fluctuations that cause the TEC disturbances. The height, where the disturbances occur, should be in the F
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.
