Analysis of Geomagnetic ULF wave phenomena with data from IMS Magnetometer Network and Geosynchronous satellites data from IMS Magnetometer Network and Geosynchronous satellites

(1)购买了1978年2月至1980年4月的IMS磁力计网资料和1974年至1983年SMS/GOES地球同步卫星资料。开发了计算机软件，以便我们实验室的超小型计算机可以进行大部分数据分析。(3)研究了磁层突然膨胀时的磁场变化。研究发现，膨胀效应在低纬度地区以快模膨胀波传播，在高纬度地区以横模膨胀波传播。这与磁层突然压缩（sc）的情况类似，但在意义上相反。(4)对动力探测2号卫星在低纬度（地磁纬度：32^o）和低空（750km）探测到的Psc（与sc相关的地磁脉动）进行了分析。地磁图显示，每条力线都有自己的本征周期，低纬度为1秒，高纬度为400秒。(5)如果太阳风动压存在振荡变化，且周期大于该效应在磁层的传播时间，则该效应将以与sc相同的机制传递到地面。考虑到这一想法，对地面磁图和太阳风数据进行了检查，发现了一个符合预期的事件。在经度相距较远的低纬度台站，振荡周期为6 ~ 16 min，且波形一致。在高纬度地区，不同站点的周期和相位不同。根据我们目前所做的分析，建立了一个sc模型。

(1) The IMS Magnetometer Network data for the period, February, 1978 - April, 1980 and SMS/GOES geosynchronous Satellites Data for 1974 - 1983 were purchased.(2) The computer software was developed so that the most of the data analysis could be made by the super-mini-computer in our laboratory.(3) Magnetic variations during sudden expansions of the magnetoshere were studied. It was found that the effect of the expansion was transmitted by the fast mode expansion wave to low latitudes and by the transverse mode to high latitudes. This is similar but opposite in sense to the case of the sudden compression of the magnetosphere, (sc).(4) An analysis was made for a Psc (geomagnetic pulsation associated with sc) detected by the Dynamic Explorer-2 satellite at low latitude (geomagnetic latitude: 32^o) and at low altitude (750km). The period ws about 13 sec. The inspection of ground magnetograms showed each line of force was resonated with its own eigen period ranging 1 sec in low latitudes to 400 sec in high latitudes.(5) If there is an oscillatory variation in the solar wind dynamic pressure and if the period is longer than propagation time of the effect in the magnetosphere, the effect will be transmitted to the ground by the same mechanism as sc. Keeping this idea in mind, gound magnetograms and solar wind data were checked and an event was found which fulfils expectation. The oscillation (the period: 6-16 min) appeared coherently with similar waveform at low latitude stations widely separated in longitude. The period and phase varied from station to station in high latitudes.(6) A model for sc was developed based upon our analyses made so far.