温度变化对GNSS测站非线性垂直运动的影响研究

Influence of temperature changes on nonlinear vertical movement of GNSS stations

温度变化引起的热膨胀效应会造成全球导航卫星系统(GNSS)天线观测墩和基岩的周期变化,从而引起GNSS测站的非线性运动。基于2014—2020年美国西海岸地区9个GNSS测站数据和相应的温度数据,本研究引入热传导方程和全局优化的最小二乘拟合方法,探究了热膨胀效应对测站垂直位移的影响,并分析了测站高程对热膨胀效应位移的影响。研究发现,实验区域测站基岩热膨胀引起的垂向位移占总热膨胀位移的平均比例约为53.6%。热膨胀效应引起的垂直位移周年周期振幅显著大于半年周期振幅,尤其在高海拔测站更为明显。热膨胀效应引起的周年周期非线性运动对测站季节性位移变化周年项的平均贡献为9.39%,热膨胀位移的半年周期信号对GNSS季节性变化半年项的贡献为4.68%。以上发现说明了热膨胀效应是造成GNSS测站高程方向非线性运动的重要因素,测站海拔是影响该效应的关键因素。

The thermal expansion effect caused by the temperature change can cause periodic changes in the global navigation satellite system(GNSS)antenna observation pillars and bedrock,which leads to the nonlinear movement of GNSS stations.Based on the data of nine GNSS stations along the West Coast of the United States from 2014 to 2020 and the corresponding temperature data,this study introduced the heat transfer equation and the globally optimized least squares fitting method to explore the influence of thermal expansion effect on the vertical displacement of the stations and analyzed the influence of station elevation on the thermal expansion effect displacement.The results find that the vertical displacement caused by thermal expansion of the bedrock of the stations in the test area accounts for an average of 53.6%of the total displacement.The annual periodic amplitude of the vertical displacement caused by thermal expansion is significantly larger than that of the half-year periodic amplitude,particularly at higher elevations.The study also reveals that the annual periodic nonlinear movement due to the thermal expansion effect contributes 9.39%on average to the seasonal variation in the annual term of the GNSS stations.The half-year periodic signal of thermal expansion displacement contributes 4.68%to the seasonal variation in the half-year term of the GNSS stations.These results highlight the importance of thermal expansion effects in causing nonlinear movement along the elevation direction of GNSS stations,with station elevation identified as a key influencing factor.