Climatological Characteristics of the Polar Ionosphere Based on the Sondrestrom

• Main Authors: Young-Sil Kwak, Byung-Ho Ahn
• Format: Article
• Language: English
• Published: Korean Space Science Society (KSSS) 2002-03-01
• Series: Journal of Astronomy and Space Sciences
• Subjects: ionospheric conductance; electric field; current density; ground magnetic disturbance
• Online Access: http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2002/v19n1/OJOOBS_2002_v19n1_75.pdf
• ISSN: 2093-5587; 2093-1409

The climatological characteristics of the polar ionosphere is examined in terms of the ionospheric conductance and electric field. For this purpose, 109 days of measurements from the Sondrestrom incoherent scatter radar are utilized. By combining these two quantities, it is possible to deduce the overhead ionospheric current distributions. The ionospheric current density thus obtained is compared with the corresponding ground magnetic disturbance. Also examined is the effect of the field-aligned current on the ground magnetic disturbance, particularly on the D component. Several interesting climatological characteristics about the ionosphere over the Sondrestrom are apparent from this study: (1) The conductance distribution is mainly due to solar EUV radiation during day-time. On the other hand, the conductance distribution during the night-time is very low. (2) The conductance distribution over the polar cap region during the day-time is controlled mostly by the solar EUV radiation, while it is extremely low during night-time with the Hall and Pedersen conductances being 1.6 and 1.2 siemen, respectively. (3) The region of the maximum N-S electric field tend to locate in the dayside sector. The E-W component of the electric field is stronger than that over Chatanika. (4) The E-W auroral ionospheric current(JE) is more important in the sunlit hemisphere than the night hemisphere. And a strong southward current is noted in the prenoon sector. (5) There is a significant correlation between the overhead ionospheric current and the simultaneously observed ground magnetic disturbance. However, the assumption for the infinite sheet current approximation is far from realistic, underestimating the current density. And the correlation between Δ H and JE is higher than the one between Δ D and JN, indicating that field-aligned current affects significantly Δ D.