论文标题
探索地球的电离层及其对使用UGMRT和SKA的低射频观察的影响
Exploring Earth's Ionosphere and its effect on low radio frequency observation with the uGMRT and the SKA
论文作者
论文摘要
地球的电离层引入了系统效应，以限制低频（$ \ lyssim 1 $ \，GHz）的无线电干涉仪的性能。对于严重的地磁活动或涉及干涉仪的较长基线的观察，这些效果变得更加明显。 UGMRT是平方公里阵列（SKA）的探路者，位于赤道电离异常（EIA）和磁性赤道之间的北部波峰之间。因此，该望远镜更容易容易出现严重的电离层条件，并且是研究电离层的独特无线电干涉仪。在这里，我们对GMRT提出了235 \，MHz观察结果，显示出在太阳最小值上的电离层活性。在这项工作中，我们表征了GMRT观察到的电离层障碍，并将其与电离层研究和观察结果进行了比较，并与其他望远镜（如VLA，MWA和LOFAR）进行了观察。我们估计了整个GMRT阵列的电离层总电子含量（TEC）梯度，该阵列显示出与全球导航卫星系统（GNSS）相比，灵敏度更高的数量级。此外，本文使用了根据UGMRT，VLA，Lofar和MWA的观测值估计的电离层特性，以预测未来对SKA1-MID和SKA1-LOW的低频观察的影响。
The Earth's ionosphere introduces systematic effects that limit the performance of a radio interferometer at low frequencies ($\lesssim 1$\,GHz). These effects become more pronounced for severe geomagnetic activities or observations involving longer baselines of the interferometer. The uGMRT, a pathfinder for the Square Kilometre Array (SKA), is located in between the northern crest of the Equatorial Ionisation Anomaly (EIA) and the magnetic equator. Hence, this telescope is more prone to severe ionospheric conditions and is a unique radio interferometer for studying the ionosphere. Here, we present 235\,MHz observations with the GMRT, showing significant ionospheric activities over a solar minimum. In this work, we have characterised the ionospheric disturbances observed with the GMRT and compared them with ionospheric studies and observations with other telescopes like the VLA, MWA and LOFAR situated at different magnetic latitudes. We have estimated the ionospheric total electron content (TEC) gradient over the full GMRT array which shows an order of magnitude higher sensitivity compared to the Global Navigation Satellite System (GNSS). Furthermore, this article uses the ionospheric characteristics estimated from the observations with uGMRT, VLA, LOFAR and MWA to forecast the effects on the low-frequency observations with the SKA1-MID and SKA1-LOW in future.
