Multi-channel and multi-polarization radar measurements around the NEEM site
Multi-channel and multi-polarization radar measurements around the NEEM site
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NEEM 站点周围的多通道和多极化雷达测量
DOI：
10.5194/tc-12-2689-2018
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
J. Paden
中科院分区：
文献类型：
--
作者：
Jilu Li;Jose A. Vélez González;C. Leuschen;A. Harish;P. Gogineni;M. Montagnat;I. Weikusat;F. Rodríguez‐Morales;J. Paden
抽象的。从多极化测量推断的冰特性，如双折射和晶体取向组构(COF)，可以提供对冰应变、粘度和冰流的洞察。2008年，冰盖遥感中心(CReSIS)使用地基甚高频(甚高频)雷达在北格陵兰岛Eemian冰钻(NEEM)地点周围进行了多通道和多极化测量。该系统的工作带宽为30 MHz，中心频率为150 MHz。本文描述了雷达系统、天线配置、数据采集以及对该数据集的处理和分析。在单轴冰晶模型的框架内，我们发现在冰核周围100 km2范围内，冰的双折射主导了共极化和交叉极化测量的功率变化模式。普通波和非常波之间的相移随深度的增加呈非线性增加。冰视轴位于接近垂直平面的平面上，并根据深度与冰的分界线垂直或平行。冰光轴垂直方向的平均倾角约为11.6°，其平面可在100km2的 范围内顺时针或逆时针旋转约10°，并在特定位置随深度增加而略有逆时针旋转。雷达观测、模拟和冰芯组构数据之间的比较是非常一致的。我们利用冰晶c轴的方位和纬度测量，计算了不同深度的有效纬度。我们得到了与垂直轴成9.6°的平均有效c轴倾角，与根据雷达偏振测量估算的平均光轴倾角非常接近。这些比较使我们有信心应用这种偏振无线电回波探测技术来推断没有冰芯测量的地点的冰结构轮廓。
Abstract. Ice properties inferred from multi-polarization measurements, such as birefringence and crystal orientation fabric (COF), can provide insight into ice strain, viscosity, and ice flow. In 2008, the Center for Remote Sensing of Ice Sheets (CReSIS) used a ground-based VHF (very high frequency) radar to take multi-channel and multi-polarization measurements around the NEEM (North Greenland Eemian Ice Drilling) site. The system operated with 30 MHz bandwidth at a center frequency of 150 MHz. This paper describes the radar system, antenna configurations, data collection, and processing and analysis of this data set. Within the framework derived from uniaxial ice crystal model, we found that ice birefringence dominates the power variation patterns of co-polarization and cross-polarization measurements in the area of 100 km2 around the ice core site. The phase shift between ordinary and extraordinary waves increases nonlinearly with depth. The ice optic axis lies in planes that are close to the vertical plane and perpendicular or parallel to the ice divide depending on depth. The ice optic axis has an average tilt angle of about 11.6° vertically, and its plane may rotate either clockwise or counterclockwise by about 10° across the 100 km2 area, and at a specific location the plane may rotate slightly counterclockwise as depth increases. Comparisons between the radar observations, simulations, and ice core fabric data are in very good agreement. We calculated the effective colatitude at different depths by using azimuth and colatitude measurements of the c axis of ice crystals. We obtained an average effective c axis tilt angle of 9.6° from the vertical axis, very comparable to the average optic axis tilt angle estimated from radar polarization measurements. The comparisons give us confidence in applying this polarimetric radio echo sounding technique to infer profiles of ice fabric in locations where there are no ice core measurements.
影响因子：
3.4
作者：
R. Drews;O. Eisen;D. Steinhage;I. Weikusat;S. Kipfstuhl;F. Wilhelms
通讯作者：
R. Drews;O. Eisen;D. Steinhage;I. Weikusat;S. Kipfstuhl;F. Wilhelms
影响因子：
5.2
作者：
Bamber, J. L.;Griggs, J. A.;Steinhage, D.
通讯作者：
Steinhage, D.