磁纬20°以下地区哨声多台宽带定向观测及其初步结果

武汉大学哨声组与日本名古屋大学空电研究所合作于1988年1月在我国南方进行了哨声多台宽带定向测量。利用近两年研制的宽带数字化频率追踪定向分析系统,首次获得了磁纬20°以下地区哨声波出口区与偏振状态的实验结果。初步分析发现,在湛江附近（磁纬约10°N）存在一个比较稳定的哨声路径出口区,三台同时接收到的哨声大多从这同一出口区透射出来;有时存在两个出口区,一个仍位于湛江附近,另一个位于桂林和武昌之间;沿两条不同路径传播的同源哨声具有几乎相同的色散。本文所做的非导管射线追踪计算能比较满意地解释定向实验结果。另外,此次观测中还发现一些新的有意义的现象,如记录到近百例两跳、三跳及五跳回波等,这在低纬地区是非常少见的。

MULTI-STATIONED WIDEBAND DIRECTION FINDING MEASUREMENTS FOR WHISTLERS AT GEOMAGNETIC LATITUDES BELOW 20° IN CHINA AND SOME EARLY RESULTS

Simultaneous direction finding measurements of very low latitude whistlers were made in January 1988 cooperatively by Whistler Group of Wuhan Univ., China and Research Institute of Atmospherics, Nagoya Univ., Japan at three stations in South China. Making use of a recently developed wideband and digital frequency-tracking DF analysing system, some useful information on the arrival directions and polarizations etc. of whistlers at geomagnetic latitudes below 20° has been obtained. It was found that there is a stable exit region near Zhanjiang （geomag. lat. 10°N）, from which most of the coincident whistlers received at the 3 stations originate. In some cases, such coincident whistlers came from two different exit regions, one being still located near ZJ, while another one between GL and WC. The whistlers propagating along these two different discrete paths have nearly the smae dispersion values. These DF results are in good agreement with the results of non-ducted ray tracing computations. Besides, some interesting phenomena which were seldom seen before, such as two-hop, three-hop and five-hop echoes of low latitude whistlers, have been observed during the DF measurements.