磁层源赤道电集流效应的地方时变化和地区影响

THE LOCAL TIME VARIATION AND REGIONAL DISTRIBUTION OF THE EQUATORIAL ELECTROJET CAUSED BY THE MAGNETOSPHERE

本文用亚洲、非洲7个低纬地磁台资料研究磁层大尺度扰动引起的赤道电集流效应,并与模式计算结果进行比较。在分析的1982年21个事件中,D_st持续下降均在5h以上,其间至少有一个小时的环电流能量增长指数及R<-25nT/h。分析中只用了各事件的-1h,0h和1h之ΔZ。ΔZ=Z-(?)_q,(?)_q是相应月份5个国际磁静日内该小时Z_q之均值。取R指数负值最大时为0h。对分布于不同经度的3个台站的21个事件ΔZ按地方时平均,与模式计算的赤道电集流随地方时的变化进行了对比;又比较了7个台站3小时序列的变化类型和模式所得之电集流演化形态,结果均有较好吻合。仅非洲一站出现了某种特殊性。这表明除磁层扰动效应外,地理和地质因素也起一定作用,其具体影响及有关机制尚待进一步考察。

Ground geomagenetic data of seven low-latitude observatories from Asia and Africa have been used to study the local time variation of the equatorial electrojet effect in response to the large scale magnetospheric disturbance.The results are compared with that of model calculation.The 21 events analysed are all from 1982.Each case includes 5 hours- In all these cases there is at least one hour when the ring current inflation index,R,was less than -25 nT/h and the Dst rematined decreasing thoughout the 5 hrs.The hour at which R index reaches its extreme negative value is taken as the key hour.△Z(=Z -Zq) of -1 h,0h and 1 h in these events are used to deduce the local time variation of △Z and compared with the model results.The type of the variation of the 5-hour series from all 7 stations are also compared with calculated evolution of the electrojet.The main feature of observations and that deduced from the model calculation are quite similar except the observations from a station of Africa.It shows some pecularity.This indicates that the geographic and geological factors may also play a role in this effect.The feature and mechanism concerned need further research.