The height of the maximum ionospheric electron density over the
MU radar
Zhang SR, Fukao S, Oliver WL, Otsuka Y
JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS
61 (18): 1367-1383 DEC 1999
Abstract:
Ionospheric F-2-layer peak height h(m)F(2) variations,
as measured over 1986-1995 by the MU radar (34.85 degrees N, 136.1 degrees
E) and as calculated with a theoretical model, are discussed. The diurnal
variations of the measured peak height for different seasons and levels of
solar activity are compared with those estimated from ionosonde M3000F(2)
and IRI predictions. Also given are the measured ion drift velocities and
meridional neutral winds needed to understand the dynamic behavior of the
F-2-layer. It is found that: (1) h(m)F(2) is generally higher during
periods of the solar maximum than during periods of the solar minimum, and
higher in summer than in winter; (2) for the solar maximum, h(m)F(2) drops
markedly in the morning and in the afternoon, while, for the solar
minimum, the h(m)F(2) minimum occurs in the morning during summer and
usually in the afternoon during winter. In general, the measured h(m)F(2)
is well reproduced by our model when we use the observed drift velocities
and plasma temperatures as inputs. Our modeling study shows that the
neutral wind contributes strongly to the diurnal variation of h(m)F(2) in
winter by lowering the ionization layer by day, particularly for the solar
maximum; it also helps to enlarge the daynight difference of h(m)F(2) in
summer. The northward electromagnetic drifts that usually cancel the
neutral wind effect have only a minor effect for the location of the MU
radar. Other features of the observed h(m)F(2) variations, e.g., the solar
maximum-minimum difference, the summer-winter difference, and the morning
and afternoon drops, are explained by the basic processes of O+
production, loss and diffusion, as influenced by the atomic oxygen
concentration and neutral and plasma temperatures. (C) 2000 Elsevier
Science Ltd. All rights reserved.
KeyWords Plus:
UPPER-ATMOSPHERE RADAR, MERIDIONAL WINDS, NEUTRAL
WINDS, LAYER HEIGHT, THERMOSPHERE, MODEL, MIDDLE, MIDLATITUDES,
TEMPERATURES, F2-LAYER
Addresses:
Zhang SR, Boston Univ, Ctr
Space Phys, Boston, MA 02215 USA
Kyoto Univ, Radio Atmospher Sci Ctr,
Uji, Kyoto 6110011, Japan
CAS, Wuhan Inst Phys & Math, Wuhan
430071, Peoples R China
Boston Univ, Dept Elect & Comp Engn,
Boston, MA 02215 USA
Publisher:
PERGAMON-ELSEVIER SCIENCE LTD, OXFORD
IDS Number:
288BB
ISSN:
1364-6826