F region behavior in the SED plume during a geomagneticsuperstorm: A case study

摘要

We report observations from the GPS total electron content (TEC), ionosonde, andMillstone Hill incoherent scatter radar showing some interesting features of the heightprofile of the ionospheric electron density that occurred during a passage of a storm-enhanced density (SED) plume during the geomagnetic superstorm on 20 November2003. First, the TEC increases to about 6.58 times the quiet day value, while the F peakplasma density (NmF2) only enhances by a factor of 1.37. Second, the F2 layer peakheight (h_m,F2)is dramatically lifted from the quiet time altitude of 250 km to an unusualaltitude of 577 km. Furthermore, the topside Chapman scale height HT is larger by afactor of 6.25 compared to the quiet time value. As a result, the electron density contentwith an a-Chapman function above 700 km contributes about 59% to the total contentduring the SED event. Our analysis shows that during a passage of the SED plume, theenhancement of TEC is mainly attributed to the great increase of HT with a very high hmF2.