HR: 16:45h
AN: SA22C-04    [PDF]
TI: Global Characteristics of the Equatorial Anomaly of the low Latitude Ionosphere Observed by IMAGE/FUV
AU: * Sagawa, E
EM: esagawa@crl.go.jp
AF: Communications Research Laboratory, 4-2-1 Nukuikitamati Koganeisi, Tokyo, 184-8795 Japan
AU: Immel, T J
EM: immel@ssl.berkeley.edu
AF: Space Science Laboratory UC berkeley, Continental Dr. at Grizzly Blvd., Berkeley, CA 94720-7450 United States
AU: Frey, H U
EM: hfrey@imfuv.ssl.berkeley.edu
AF: Space Science Laboratory UC berkeley, Continental Dr. at Grizzly Blvd., Berkeley, CA 94720-7450 United States
AU: Mende, S B
EM: mende@ssl.berkeley.edu
AF: Space Science Laboratory UC berkeley, Continental Dr. at Grizzly Blvd., Berkeley, CA 94720-7450 United States
AB: The Equatorial Anomaly (EA) of the low latitude ionosphere has been studied extensively since its discovery by Nanba and Maeda (1939) and Appleton (1946). The EA is produced basically by the uplift of the F-layer plasma at the magnetic equator by zonal electric fields, which subsequently enhances the density of the plasma at the base of field lines on both sides of the magnetic equator. Also important for the EA development is the field-aligned plasma flow which is driven by the neutral wind. Because the electric field is mainly generated through interaction between the neutral atmosphere and the plasma, the EA is thought to represent the coupling of the neutral atmosphere and the ionosphere at low latitude. However, it has been difficult to characterize global EA features observationally because of the lack of global observation of the ionosphere at low latitudes. IMAGE/FUV takes the images of 135.6 nm nightglow emission globally. This enables us to analyze characteristics of the nighttime EA distribution as it changes with the longitude. The IMAGE/FUV instrument images the whole earth visible from the maximum distance of 40,000 km, and observed the low latitude ionosphere for more than 6 hours continuously in early 2002, while repeating observations every two minutes. For analysis we use constant local time maps (LT maps). LT maps are constructed by binning the IMAGE/FUV data of several consecutive days into the local　time, latitude and longitude bins. Then, by choosing bins with a constant local time, we can obtain the LT map of 135.6 nm emission. By taking this method, longitudinal variations of EA can be easily seen. LT maps of 135.6 nm nightglow indicate that there is a considerable variation of the EA development depending on longitude.
DE: 0310 Airglow and aurora
DE: 2400 IONOSPHERE
DE: 2411 Electric fields (2712)
DE: 2415 Equatorial ionosphere
DE: 2437 Ionospheric dynamics
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting