Characterization of the Effects of Temperature and Instrument Drift in Long-Term Comparative Geomagnetic Vector Observations

Zhaobo He,Xingxing Hu,Xiaoyu Shen,Yuntian Teng,Gaochuan Liu,Xiuxia Zhang

doi:10.3390/atmos13030449

Abstract

In order to minimize interruptions to recording, geomagnetic observatories usually use a back-up instrument operating simultaneously with the primary instrument in order to obtain comparative observations. Based on the correction parameter calculation method established in the previous work, we focused on the effects of temperature and instrument drift on the comparative geomagnetic vector observations. The linear influence of temperature on the comparative data was shown to be variable. The relative temperature coefficient changed around the temperature inflection point and showed a V-type distribution in a scatter plot. This conclusion was verified in laboratory experiments. The long-term time drift between the comparative instruments exhibits a linear pattern, and the fitness of the correction model can be evaluated by the degree to which the residual distribution of the fitted straight line conforms to the normal distribution. However, the absolute value of the long-term time drift between variometers with the same type of probe is very small. Therefore, long-term time drift correction should be carried out with care. The associated analysis and conclusions have the potential to benefit data agreement correction of long-term comparative geomagnetic vector observations and comparative testing of the performance of vector instruments.

Highlights

Comparative geomagnetic vector observations are a mutually corroborating operational recording process and are a fundamental means of ensuring operational continuity and stability for land-based geomagnetic repeat stations [1–3]
As the sampling rate and resolution of magnetic variometers continue to increase, non-negligible measurement differences arise between comparative instruments [4,5]
Theiscalculated mean, which means that the length of the error bar covers even its histoAfter daily correction, a linear regression of considered the geomagnetic vector to theand a gram, no significant relative attitude angle is to exist in difference that direction temperature or scale factor to the time series gives the relative temperature coefficient value of zero is taken

Summary

Introduction

Comparative geomagnetic vector observations are a mutually corroborating operational recording process and are a fundamental means of ensuring operational continuity and stability for land-based geomagnetic repeat stations [1–3]. The characteristics of two long-term correction parameters, the relative temperature coefficient and the long-term time drift, are analyzed and discussed using observatory data from a broader source and a longer time span than in previous work. In terms of temperature effects, we have already identified some special cases where the relative temperature coefficient varies relatively significantly during different processes of warming and cooling, which means that this parameter has temperature asymmetry This feature was further analyzed and, more importantly, proved to be somewhat generalized by four sets of two-year-long comparative data. It was eventually found that the absolute value of the long-term time drift was very small or even negligible for comparative measurements performed using the variometers with the same type of probe. It is recommended that long-term time drift correction be carried out with caution

Data and Methodology

Characteristics of the Relative Temperature Coefficient

Characteristics of Long-Term Time Drift

Conclusions