Remote GPS measurements to improve SAR ice monitoring

星载合成孔径雷达（SAR）观测可用于测量南极冰盖内部的结构和速度。迄今为止，大多数SAR任务都使用l波段频率（1-2 GHz），但现在人们的兴趣转向了低频p波段信号（约430 MHz），因为它们对冰的穿透能力更强。巴斯大学和欧洲航天局目前都在参与有关欧空局未来卫星p波段SAR设计的可行性研究。极地轨道上的p波段sar，如定于2014年发射的欧空局生物质卫星，有可能绘制出冰盖的三维结构。然而，它们的信号将受到显著的电离层影响，包括法拉第旋转、距离离焦、距离延迟和干涉相位偏差。在系统设计中必须考虑电离层，但目前还没有必要的电离层测量。该项目将提供南极地区的测量数据，并为p波段SAR任务的成功奠定基础。这个项目包括设备开发、实地考察和分析。实地考察的目的是部署改进的GPS接收设备，该设备将首次测量南极偏远地区的总电子含量（TEC）、等离子体速度和电离层闪烁。为了实现这一目标，将部署8个新的GPS接收器，在两年的时间里在极光和极帽区域进行长期测量。来自南极低纬度地区的额外数据将由国际合作伙伴提供。这些测量结果将用于开发南极电离层的多尺度模型。该模型将是SAR设计的关键输入，将最大限度地减少电离层对未来卫星任务冰测量的影响。

Space-borne synthetic aperture radar (SAR) observations can be used to measure structure and velocity within the Antarctic ice sheet. Most SAR missions to date have used L-band frequencies (1-2 GHz) but interest is now turning to lower-frequency P-band signals (around 430 MHz) because they have greater penetration of the ice. Both the University of Bath and BAS are currently involved in feasibility studies relating to P-band SAR design for future ESA satellites. P-band SARs in polar orbits such as the ESA BIOMASS satellite due to launch in 2014, have the potential to map out the three-dimensional structure of ice sheets. However, their signals will suffer from significant ionospheric effects including Faraday rotation, range defocusing, range delay and interferometric phase bias. The ionosphere must be taken into account in the system design but the necessary ionospheric measurements to do this do not currently exist. This project will deliver the measurements for the Antarctic region and lay the foundation for successful P-band SAR missions. This project involves equipment development, fieldwork and analysis. The objective of the fieldwork is to deploy modified GPS receiving equipment that will for the first time take measurements of total electron content (TEC), plasma velocity and ionospheric scintillation at remote locations across the Antarctic. To achieve this, eight new GPS receivers will be deployed to undertake long-term measurements in the auroral and polar-cap regions over a two year period. Additional data from lower Antarctic latitudes will be provided by international partners. The measurements will be used to develop a multi-scale model of the Antarctic ionosphere. This model will be a critical input to SAR design that will minimize the impact of the ionosphere on ice measurements for future satellite missions.