Long term ionospheric electron content variations over Delhi
Long term ionospheric electron content variations over Delhi
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DOI：
10.1007/s00585-001-1635-8
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发表时间：
2000-12
影响因子：
1.9
通讯作者：
J. K. Gupta;L. Singh
中科院分区：
文献类型：
--
作者：
J. K. Gupta;L. Singh
1975-80 年和 1986-89 年在印度德里（地理坐标：北纬 28.63°，东经 77.22°；地磁坐标：北纬 19.08°，东经 148.91°；倾角北纬 24.8°）观测到的电离层电子含量（IEC），属于太阳周期上半期太阳活动的上升阶段21和22分别用于研究昼夜、季节、太阳和磁活动的变化。平静天气下 IEC 季节平均值的日变化显示出与太阳活动旺盛时的春分和冬季白天峰值相当的次峰值。 IECmax（IEC 白天最大值，每天一次）仅在德里太阳活动频繁期间显示冬季异常。此外，IECmax 与 F10.7 呈正相关，春分时约为 200 通量单位，冬季和夏季均为 240 单位；对于更大的 F10.7 值，IECmax 在所有季节基本恒定。研究发现，在太阳活动旺盛的夏季，IECmax 与磁活动 (Ap) 呈正相关。冬季IECmax在两个太阳周期中都与Apin低太阳活动呈正相关，与高太阳活动呈负相关。在春分点IECmax 独立于Apin 两个太阳周期都处于低太阳活动状态。对IECmax逐日变化的研究显示了单日和隔日异常、赤道电喷流强度控制的半年和年变化以及太阳自转引起的27天周期性。 关键词：电离层（赤道电离层）·磁层物理（磁层·电离层相互作用）·无线电科学（电离层物理）
Ionospheric electron content (IEC) observed at Delhi (geographic co-ordinates: 28.63°N, 77.22°E; geomagnetic co-ordinates: 19.08°N, 148.91°E; dip Latitude 24.8°N), India, for the period 1975–80 and 1986–89 belonging to an ascending phase of solar activity during first halves of solar cycles 21 and 22 respectively have been used to study the diurnal, seasonal, solar and magnetic activity variations. The diurnal variation of seasonal mean of IEC on quiet days shows a secondary peak comparable to the daytime peak in equinox and winter in high solar activity. IECmax(daytime maximum value of IEC, one per day) shows winter anomaly only during high solar activity at Delhi. Further, IECmaxshows positive correlation with F10.7up to about 200 flux units at equinox and 240 units both in winter and summer; for greater F10.7values, IECmaxis substantially constant in all the seasons. IECmaxand magnetic activity (Ap) are found to be positively correlated in summer in high solar activity. Winter IECmaxshows positive correlation withApin low solar activity and negative correlation in high solar activity in both the solar cycles. In equinox IECmaxis independent ofApin both solar cycles in low solar activity. A study of day-to-day variations in IECmaxshows single day and alternate day abnormalities, semi-annual and annual variations controlled by the equatorial electrojet strength, and 27-day periodicity attributable to the solar rotation.Key words:Ionosphere (equatorial ionosphere) · Magnetospheric physics (magnetosphere · ionosphere interactions) · Radio science (ionospheric physics)