Abstract: Minute value data of geoelectric field at Mengcheng Station in Anhui Province in 2002 have been analyzed and processed. The results indicate that clear normal daily variation and electromagnetic storm have been recorded; variations of data in long and short polar distances of same orientation are consistent; comparing NW component with vector sum of SN and WE in NW orientation, the errors are small. The linear polarization direction angles in magnetostatic and electromagnetic storm days are stable; the change is from N80°W to N100°W. They deflect obviously when there are interfere and thunderstorm. The orientation angles of telluric field change largely in all days. As results of rainfall, line breakdown and instrumental instability, a few data are anomalous. The observation quality will be higher if the condition is improved.

Key words: Telluric field, Electromagnetic storm, Linear polarization, Observation quality