基于VLBI和GPS测量2009年7月22日日全食期间电离层TEC变化

Ionospheric TEC Measurement with VLBI and GPS During the Total Solar Eclipse of 22 July 2009

2009年7月22日上午发生的日全食是21世纪全食持续时间最长的日全食,跨越了中国北纬约30°的广大地区,为研究太阳对地球电离层的影响提供了一次难得的机会。上海位于此次日全食带中心线附近,为此,上海佘山站、乌鲁木齐南山站和日本鹿岛站开展了VLBI联合观测实验。与此同时,TEC测量还配合使用了GPS观测站。本文介绍了此次日全食观测实验的背景、测量方案、观测实验详情和数据处理流程。根据相关处理结果,利用二维条纹搜索方法在上海-乌鲁木齐基线获得了优质干涉条纹,预示着VLBI测量取得成功。对单站GPS数据的初步分析表明,日全食食甚时刻TEC值存在快速下降。此次观测实验预期将首次获得电离层TEC变化的VLBI实测结果,并开展VLBI与GPS测量结果的比较研究。

The longest total solar eclipse during the 21st century, occurred over China at latitudes of about 30°N in the morning of 22 July 2009, provides a unique opportunity to investigate the influence of the sun on the earth upper ionosphere. For Shanghai is located near the central line of the total eclipse belt, a VLBI experiment for ionospheric Total Electron Content （TEC） measurement has been carried out with participation of Shanghai, Urumqi and Kashima stations. Meanwhile, a number of GPS receiving system are also used in the experiment. The background and methodology for the experiment are briefly described, followed by the introduction of observation details and data processing procedure. Based on the cross correlation results, good fringes have been detected on the Shanghai-Urnmqi baseline with the 2 dimensional fringe search technique, which indicate that the VLBI measurement of TEC was performed successfully. The data analysis of a single GPS station led to a preliminary result which shows the sudden decrease in TEC at the time of maximum eclipse. We expect to acquire the first VLBI results for TEC measurement, and compared with the results from GPS observations.