Topband: 160 Propagation & Weather

[Michael Keane, K1MK]

On Fri, 01 Nov 2002, "Charles Hutton" wrote:

> I'd agree - Kazimrovsky's paper is what is called a literature survey 

Yes, of course it's a review paper; there's nothing wrong with that. 

Granted that a review paper is not the best reference to cite for
observations of a specific phenomenon. In his defense Tom did say the
work was only touched upon in the review. Although to be honest I'd
interject that even saying that the subject was touched upon in the
review is something of stretch. Nevertheless, references to the original
papers in question are in there.

Generally, a review paper is not such a bad place to begin reading if
one has a bit of intellectual curiosity about either the larger context
of the specific question at hand or the historical development of the
field. 

The general topics of interaction and coupling between the Ionosphere,
Thermosphere & Mesosphere (ITM) and how conditions in the lower
atmosphere might influence the ITM by setting the lower boundary
conditions at the mesopause are both areas that have come under
increasingly active study over the past decade. 

That NASA is currently flying a mission such as TIMED
(<www.timed.jhuap.edu>) specifically for making observations of the
Mesosphere/Lower Thermosphere/Ionosphere demonstrates that the question
of "meteorological" effects on the ionosphere, at least the long-term,
global-scale, "climatological" sort of influences, is taken quite
seriously. 

But this also highlights one weakness of the K&K review: most of its
references are to literature that's more than 10 years old now. Thus the
more recent work on "sprites" and "elves" are not mentioned. And it's
precisely these optical diagnostics that clearly demonstrate that there
is a local, transient ionospheric effect in the D & E layers associated
with lightning. (Pete N4ZR's reference to Barrington-Leigh's thesis is
not a bad starting point; a somewhat more readable version of that can
be found at
<http://nova.stanford.edu/~vlf/publications/theses/cpblThesisHyper.pdf>) 
Now, to what's most relevant. The transient heating and ionization of
the lower ionosphere by lightning might conceivably result in
significant and widespread impacts on radio propagation at 1.8 MHz. In
which case it should have been noticed sooner than now. 

At the other extreme, the impact upon radio propagation at MF and higher
frequencies could be highly localized, extremely transient and subtle.
Which is what the models for the sprite/elve phenomenon suggest.

73, 
Mike K1MK

Michael Keane K1MK
k1mk@arrl.net
________________________________________________
PeoplePC:  It's for people. And it's just smart. 
http://www.peoplepc.com