Comparison of K-index Calculations between Several Geomagnetic Stations during IQDs and IDDs

• Main Authors: Junga Hwang, Hang-Pyo Kim, Young-Deuk Park
• Format: Article
• Language: English
• Published: Korean Space Science Society (KSSS) 2013-09-01
• Series: Journal of Astronomy and Space Sciences
• Subjects: K-index; BOH magnetometer; IQDs and IDDs
• Online Access: http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2013/v30n3/OJOOBS_2013_v30n3_169.pdf

BOH magnetometer was installed at Mt. Bohyun in 2007 and has provided continuous dataset for 3-axis geomagnetic field over the South Korea. We have calculated real-time K-index based on BOH magnetic field data using well-known FMI method. Local K-index is calculated eight times a day, per every three hours. To calculate K-index, it is critical to get the Quiet Day Curve (QDC). For QDC calculation, we take the previous one month’s average of H-component. In this paper, we compared four geomagnetic stations’ magnetic field data over South Korea and Japan and K-indices of each stations; Bohyun, Gangneung, Jeju, and Kakioka for two years data, 2011-2012. To investigate the difference depending on the latitude, longitude and local time in more detail, we compare K-index on International Quiet Days (IQDs) and International Disturbed Days (IDDs). As a result, we report the correlation between local K-indices are higher than those between Kp and local K-indices, and the correlation is much better after sunset than after sunrise. As the geomagnetic activity becomes stronger, the correlation between the local K-indices and global Kp-index become higher.