利用GPS计算的TEC变化率监测太阳耀斑

MONITORING SOLAR FLARE BY CALCULATING CHANGE RATE OF TEC WITH GPS DATA

给出了利用双频GPS载波相位观测值计算各个卫星沿观测方向的电子总量 (TEC)变化率的方法 ,用该方法计算了 2 0 0 0年 7月 12日和 7月 14日两次级别分别为X1.9级和X5 .7级太阳耀斑前后一周各个卫星的TEC变化率。分析表明 ,在太阳耀斑爆发当天 ,如果卫星交叉点是在中纬度地区运动 ,沿观测方向TEC变化率除耀斑爆发的一段时间外 ,其它时间变化相对平稳 ,并且在耀斑爆发一天后 ,TEC变化率趋于正常 ;如果卫星交叉点纬度低于 30° ,那么在耀斑爆发前一天 ,各个卫星沿观测方向的TEC变化率发生“异常” ,即变化率增加很快 ,而且交叉点运行的纬度越低 ,TEC变化率的增量越大。比较了分析太阳耀斑的两种数据处理方法 :求解沿天顶方向上电子总量 (VTEC)和求解TEC变化率的方法 ,指出求解TEC变化率的方法不必考虑仪器偏差的影响 ,能更好地监测较小级别的太阳耀斑。

Firstly, the method of calculating the change rate of TEC of each satellite with the dual frequency GPS data is introduced. By this method, the change rate of TEC of each satellite in a week before and after the two solar flares of class X1.9 and class X5.7 on July 12 and July 14,2000 is calculated. Analysis shows that if the IPP moves in the middle latitude on the day the flare bursts, the change rate of TEC is relative steady except in the moment when the flare bursts and it trends towards normal after the day of flare. If the IPP moves in the low latitude, the change rate of TEC along the observation of each satellite before the day the flare burst increases fast, and the lower latitule of the IPP is,the bigger increment of the change rate of TEC well be. In this paper two methods are compared with each other: one of them is the method for calculating the VTEC, the other is for calculating the change rate of TEC. The later needs not to consider the instrumental bias, it can monitor the flare of smaller class.