Indexed on: 14 Jun '11Published on: 14 Jun '11Published in: Earth, Planets and Space
We analyzed peak electron densities (NmF2) and peak heights (hmF2)of F2 layer, measured by a digisonde at Anyang (37.4°N, 127.0°E, Geomag = 27.7°N, 196.9°E) during the period of April 1998 through April 2008. The Anyang NmF2 and hmF2 values averaged over each month show generally good linear relationship with increasing solar activities for all local time and for various geomagnetic activities. The change of the noon NmF2 with increasing solar flux indices (F10.7) is much slower in summer than in other seasons, and the NmF2 difference between noon and midnight is minimized in summer. The hmF2 varies with F10.7 from 200 km to 350 km at noon and from 300 to 450 km at midnight, but the hmF2 variations do not show seasonal difference significantly for all local time. The semi-annual variations of NmF2 and hmF2 are apparent and the winter anomaly of NmF2 is also clearly seen for most cases of geomagnetic and solar activities. The Anyang NmF2 values are in good agreement with the IRI 2007 model except for high solar and geomagnetic activity cases. However, the Anyang hmF2 values at midnight are significantly higher than the IRI model, being higher by up to ∼100 km for high solar activities.