Stability analysis of geomagnetic baseline data obtained at Cheongyang observatory in Korea

Abstract. The stability of baselines produced by Cheongyang (CYG) observatory from the period of 2014 to 2016 is analysed. Step heights of higher than 5 nT were found in H and Z components in 2014 and 2015 due to magnetic noise in the absolute-measurement hut. In addition, a periodic modulation behaviour observed in the H and Z baseline curves was related to annual temperature variation of about 20 °C in the fluxgate magnetometer hut. Improvement in data quality was evidenced by a small dispersion between successive measurements from June 2015 to the end of 2016. Moreover, the baseline was also improved by correcting the discontinuity in the H and Z baselines.