2009年7月22日日全食引起的电离层扰动及其对定位的影响

2009年7月22日发生在亚太地区的日全食,从北半球中纬地区一直延伸到南半球中纬地区.这次日食期间发生的磁暴和日食时间同步,使得电离层变化较为复杂.为了分析日食期间电离层扰动及其对定位的影响,所采用的GPS数据来源于日全食带内的重庆CORS网(4个站)、武汉CORS网(8个站)数据、IGS站WUHN、SHAO的数据,以及日偏食区域内不同纬度处的若干IGS站.通过比较日食前后连续三天的各个地方TEC变化,以及利用高采样率的CORS网数据研究日食期间TEC的瞬时变化,根据位置和时间的不同,各地日食期间TEC下降约(1~4)TECU.但是,磁暴期间TEC的响应整体表现为正相暴,偏离值达50%以上,且和日食食甚后的TEC变化相重合.同时,求解了日食期间伪距单点定位的实时精度和CORS网内中短基线的实时精度,伪距单点定位的平面精度变化不显著,高程精度下降达数十米,日食初期CORS网中基线的平面精度仍在厘米级内,高程精度仍在分米级内,但是,日食后期发生的磁暴导致基线的平面精度下降到分米级,高程精度下降到米级.

Ionospheric behavior and its effect on positioning during the solar eclipse of 22 July 2009

On 22 July 2009, an exceptionally long total eclipse of the Sun was visible within a narrow corridor that traverses the Eastern Hemisphere. A geomagnetic storm synchronized with solar eclipse and led to the complexity of the ionosphere variations. GPS observations derived from Chongqing CORS, Wuhan CORS, IGS stations such as WUHN and SHAO in Moon's umbra, and other IGS stations in Moon's penumbra. Comparing the TEC variations on three consecutive days, and based on location and time, the depression of TEC amounted to (1~4)TECU. Meanwhile, in real time point positioning, horizontal accuracy didn't have remarkable changes, but vertical accuracy declined up to several meters. And in real time baseline positioning, horizontal accuracy still reached to centimeter level, and vertical accuracy to decimeter level in the beginning of solar eclipse. But the geomagnetic storm occurred in the last of solar eclipse lead to the decline of horizontal accuracy to decimeter, and vertical accuracy to meter.