关键词: GNSS观测墩; 温度变化; 短基线时间序列; 时变特性;

Abstract: There are over 4 000 continuous GNSS reference stations in China nowadays.To ensure the stability,most of the aerials of the reference stations are settled on the top of a monument or a building roof.The concrete or metal monument may generate thermoelastic displacement due to the seasonal and daily ambient temperature variations,which exhibits large periodical oscillation in GNSS position time series.This may bias the result of surface deformation,especially in the vertical direction.In this paper,we processed two baselines data coming from 3 IGS stations with intervals less than 20 meters,and analyzed the time-varying characteristics of the thermoelastic displacement of the monument based on the baseline position time series on seasonal and daily scales.The results showed that the monuments would generate thermoelastic displacement with the seasonal ambient temperature variations,and the displacements were related to annual temperature amplitude and monument height.The temperature variation of the monument surface could also induce daily thermal displacement,and the horizontal high-frequency thermal displacement may propagate into spurious long-term signal into the time series due to the inadequate sampling rate.

Key words: GNSS monument; temperature variation; short-baseline time series; time-varying characteristics;