Dense Gps Array as a New Sensor of Seasonal Changes of Surface Loads
Dense Gps Array as a New Sensor of Seasonal Changes of Surface Loads
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DOI：
10.1029/150gm15
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发表时间：
2013-04
期刊：
影响因子：
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通讯作者：
K. Heki
中科院分区：
文献类型：
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作者：
K. Heki
全球定位系统（GPS）接收器已在世界各地部署，用于研究与地震和火山活动相关的板间和板内地壳运动以及局部变形。密集的 GPS 阵列对于通过地壳运动的周期性分量研究季节性变化的载荷也很有用。本文回顾了日本列岛季节性地壳运动的观测和预测，日本列岛拥有全国密集的 GPS 阵列和气象传感器网络。综合评估季节信号的各种来源，发现日本最大的因素是降雪，一些地区每平方米的重量超过1000公斤。其次是陆地上的各种载荷，例如大气、土壤湿度和水库蓄水，非潮汐海洋载荷也引起一定的季节性特征。季节性地壳变形是通过综合所有这些季节性负荷变化来计算的，其中一些是直接气象测量的，另一些是通过模型推断的。将它们与日本密集 GPS 阵列观测到的真实数据进行比较，并检验其一致性。 GPS 观测到的季节性信号还包括伪影，例如由大气延迟梯度和大气折射引起的尺度变化引起的伪影。我们经常讨论微妙的地壳变形信号，例如那些与无声地震有关的地震，通过消除长期和周期性成分来隔离它们。了解季节性信号及其年际变化对于消除这些不需要的信号至关重要。本文讨论了日本的案例，但本文提出的方法将在全球范围内用于研究季节性大规模重新分布。密集的 GPS 阵列可以在研究地球区域尺度的季节性质量再分布方面对卫星重力任务起到补充作用。
Global Positioning System (GPS) receivers have been deployed worldwide to study inter- and intraplate crustal motions and local deformations associated with earthquakes and volcanic activities. A dense array of GPS is also useful for studying seasonally changing load through periodic components in crustal movements. This article reviews observed and predicted seasonal crustal movements in the Japanese Islands, where both nationwide dense GPS array and meteorological sensor network are available. From comprehensive evaluation of various sources contributing to seasonal signals, the largest factor in Japan is found to be snow, weighing over 1000 kg per square meter in some regions. This is followed by various kinds of loads on the land area, such as atmosphere, soil moisture and water impoundment in reservoirs, and non-tidal ocean loads also cause certain seasonal signatures. Seasonal crustal deformations are calculated by synthesizing all these seasonal load changes, some of which are directly measured meteorologically and others are inferred through models. They are compared with real data observed by the dense GPS array in Japan, and their agreement was examined. The seasonal signals observed by GPS also include artifacts, such as those caused by atmospheric delay gradients and scale changes due to atmospheric refraction. We often discuss subtle crustal deformation signals, e.g. those associated with silent earthquakes, isolating them by removing secular and periodic components. Understanding seasonal signals and their interannual variability is crucial in removing these unwanted signals. The article discusses the Japanese case, but the methods proposed here will be useful worldwide to study seasonal mass redistributions. Dense GPS arrays may play a complementary role to satellite gravity missions in studying seasonal mass redistribution on the Earth in a regional scale.