Advances in Radio Science
www.adv-radio-sci.net
1684-9965
1684-9973
3
Kleinheubacher Berichte 2004
2005
10.5194/ars-3-441-2005
http://www.adv-radio-sci.net/3/441/2005/
http://www.adv-radio-sci.net/3/441/2005/ars-3-441-2005.html
http://www.adv-radio-sci.net/3/441/2005/ars-3-441-2005.pdf
441
447
2005-05-13
Model modulation to add smaller scale structures to large scale electron density models
R. Leitinger
E. Feichter
M. Rieger
Institut für Geophysik, Astrophysik und Meteorologie, Universität Graz, Austria
Usually regional and global electron density models provide large scale spatial structures only
and smooth out the smaller scale features of the electron density distribution.
We present a method to modulate existing electron density models by multiplication:
<i>M</i>(<i>h, φ, λ, t</i>) = <i>L</i>(<i>h, φ, λ, t</i>) × <i>S<sub>1</sub></i>(<i>h, φ, λ, t</i>) × <i>S<sub>2</sub></i>(<i>h, φ, λ, t</i>) × ... <i>S<sub>n</sub></i>(<i>h, φ, λ, t</i>)
<br>
<i>M</i>: resulting electron density distribution, <i>L</i>: large scale model,
<i>S<sub>1</sub>...S<sub>n</sub></i>: modulating models for n
the smaller scale structures; <i>h</i>: height; <i>φ, λ</i>:
geographic coordinates, <i>t</i>: Universal Time.
There are no restrictions to the nature of the large scale model provided it
takes height and
horizontal coordinates as input. Examples are models of the "profiler" type
which use large scale
"maps" for profile anchor points (e.g., E, F1, F2 peak properties) like
the International Reference Ionosphere (IRI). Typical examples for smaller
scale structures are
ridges, troughs and wavelike disturbances.
The advantage of modulation by multiplication is that there is no danger
to get zero or negative
values of electron density as long as the background and modulations are
>0 everywhere. For
each modulation model, unity means "undisturbed".