Abstract: Using 3-dimension coordinate time series from China Mainland Tectonic Environment Monitoring Network from 2010 to 2015, and based on the calculation of optimal noise models of 3 components of each station in Yunnan Area by MLE method, we analyzed correlation between the precision of GPS velocity field and the length of time series under colored noise models and white noise models through quantitative comparison. The results suggest that velocity uncertainties obtained by only 1 year time series of GPS continuous stations are overestimated in most areas of mainland China under colored noise models. With the year-to-year accumulation, the differences of velocity uncertainty of the same period between colored noise model and white-noise model declined, and the differences between these two models obtained by 3~4 year timeseries are less than 0.2mm. This study shows that we need at least 3~4 year’s data to obtain a high precision velocity field under colored noise model, and it also suggests that the velocity precision is credible and believable under the white noise model only if it was computed with at least more than 3~4 year period data.

Key words: Noise analysis of time-series, GPS reference station, China Mainland Tectonic Environment Monitoring Network