|
|
 |
|
|
Ann. Geophys., 14, 1391-1402, 1996
www.ann-geophys.net/14/1391/1996/
© European Geosciences Union 1996
Modelling high-latitude electron densities with a coupled thermosphere-ionosphere model
J. Schoendorf1, A. D. Aylward1, and R. J. Moffett2
1Atmospheric Physics Laboratory, University College London, London, UK
2Upper Atmosphere Modelling Group, University of Sheffield, Sheffield, UK
Abstract. A few of the difficulties in accurately
modelling high-latitude electron densities with a large-scale numerical model of
the thermosphere and ionosphere are addressed by comparing electron densities
calculated with the Coupled Thermosphere-Ionosphere Model (CTIM) to EISCAT data.
Two types of simulations are presented. The first set of simulations consists of
four diurnally reproducible model runs for a Kp index of 4o which differ
only in the placement of the energetic-particle distribution and convection
pattern input at high latitudes. These simulations predict varying amounts of
agreement with the EISCAT data and illustrate that for a given Kp there
is no unique solution at high-latitudes. Small changes in the high-latitude
inputs cause dramatic changes in the high-latitude modelled densities. The
second type of simulation consists of inputting statistical convection and
particle precipitation patterns which shrink or grow as a function of Kp
throughout a 3-day period 21–23 February 1990. Comparisons with the EISCAT data
for the 3 days indicate that equatorward of the particle precipitation the model
accurately simulates the data, while in the auroral zone there is more
variability in the data than the model. Changing the high-latitude forcing as a
function of Kp allows the CTIM to model the average behavior of the
electron densities; however at auroral latitudes model spatial and temporal
scales are too large to simulate the detailed variation seen in individual
nights of data.
Full Article in PDF (488 KB) |
|
|
