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Development of an impulse ice-radar for the use of thickness measurements of mountain glaciers

开发用于山地冰川厚度测量的脉冲冰雷达

基本信息

批准号：
12554015
负责人：
NARUSE Renji
金额：
$ 6.53万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

We have developed a novel ice-penetrating radar system that can be carried on a backpack. Including batteries for a three-hour continuous measurement, the total weight is 13 kg. In addition, it operates reliably down to -25°C, has a low power consumption of 24 W, and is semi-waterproof. The system has a built-in-one controller with a high-brightness display for reading data quickly, a receiver with 12-bit digitizing, and a 1-kV pulse transmitter with time variance of the pulse amplitude of less than 0.2%. The optical communications between components provides low-noise data acquisition and allows synchronizing of the pulse transmission with sampling. Measurements with this system successfully illustrate 300-m deep bed topography of Athabasca Glacier, Canada, in summers 2001 and 2002.To complement a technique to detect internal structures of seasonal snow-covers and glacier firn with ground-penetrating radar (GPR), we carried out calibration experiments and an observation of winter snow-cover (5.7 m thick dry snow with numerous ice layers) with an 800-MHz GPR. In particular, we aimed to discriminate periodic noise from radar echoes, which is inherent in GPR, and to obtain a relationship between the observed reflection strength and the magnitude of density contrasts. Experiments were made in the open space to evaluate noise levels and receiver characteristics of this system. Based on these, we removed noise from radar echoes in the snow-cover observation. We recognized numerous marked echoes in a noise-free radargram. Depths of these echoes coincided roughly with those of large density contrasts observed in the snow-pit. Thus, we argue that the echoes correspond to thin ice layers. Furthermore, the minimum density contrasts to be detected by this GPR are found to vary from about 100 to 250 kg m"3 with the depth from 1 to 6 m in the seasonal snow-cover.

我们已经开发出一种新型的可在背包上携带的冰穿透雷达系统。包括连续测量三小时的电池，总重量为13公斤。此外，它在-25 ° C以下也能可靠工作，功耗低至24 W，并且具有半防水性。该系统具有一个内置于一个控制器，具有高亮度显示器，用于快速阅读数据，一个接收器，具有12位数字化，和一个1-kV脉冲发射器的脉冲幅度的时间变化小于0.2%。组件之间的光通信提供低噪声数据采集，并允许脉冲传输与采样同步。2001年和2002年夏季，该系统成功地测量了加拿大阿萨巴斯卡冰川300 m深的河床地形。我们进行了校准实验和观测冬季积雪（5.7米厚的干雪与许多冰层）与800兆赫的探地雷达。特别是，我们的目的是从雷达回波，这是固有的探地雷达的周期性噪声的歧视，并获得所观察到的反射强度和密度对比度的大小之间的关系。在开放空间中进行了实验，以评估该系统的噪声水平和接收器特性。在此基础上，对积雪观测中的雷达回波进行了去噪处理。我们在无噪声的雷达图中识别出许多明显的回波。这些回声的深度与在雪坑中观察到的大密度对比大致一致。因此，我们认为回声对应于薄冰层。此外，该探地雷达探测到的最小密度对比度在季节性积雪的1 ~ 6 m深度范围内变化，约为100 ~ 250 kg m ~（-3）。