Influence of temperature changes on nonlinear vertical movement of GNSS stations
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.
global navigation satellite system(GNSS)thermal expansion effectnonlinear movementvertical displacement
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