xxth GENERAL ASSEMBLY OF IUGG VIENNA (AUSTRIA)

COSPAR XXVIII Plenary Meeting
Symposium MC5: 3-4 July 1990
(The
REPORT OF MEET ING
Hague , Netherlands):
ENLARGED GROUND AND SPACE DATA BASE FOR IONOSPHERIC MODELLING
L Bossy
IASB
3 Avenue Cir cul aire
B-1180 Bruxelles
BELG I UM
The symposium was organised by t h e URSI/COSPAR Task group on
the International Reference Ionosphere [ IRI ] and provi ded a
forum for the annual review of IRI-related activities . Special
emphasis was given to defining the data requirements for the
next cycl e of IRI improvements. The latest version [IRI-90] is
described in a Handbook by D Bilitza which was pre sented at
this meeting and will be released by the National Space
Science Data Center [ NSSDC] before the end of 1990 .
About 30 papers were presented and they will be published in
Advances in Space Science , with K Rawer and W R Piggott as
editors. The following account summarizes the presentations ,
discussions and proposed act ions.
1. Electron density
1.1 Lower ionosphere: K Friedrich prese nted a compilation of
about 80 profiles measured worldwide by rocket-borne radio
wave propagation experiments . He gave simple functions
describing variations with solar zenith angle at different
latitudes. A second set of profiles has been assembled by W
Singer from terrestrial radio wave propagation measure ments at
diffe rent frequenci es.
1.2 Middle ionosphere: Several anchor poi nts dete rmine the IRI
prof ile and qui te a few of these need a lar ger data base and
fu r ther i nvestigations. Concerning foE, it was decided to reexamine
the nighttime variation, which in IRI is based o n a
rather o l d and small data s e t . During daytime, IRI uses the
Kouris and Muggleton formula whic h agrees wel l with the
formula used by CCIR. Concerning the E- F val l ey parameters , it
is important to determine which true- h e ight procedure is the
most reliable f or i o nogram anal ysis . This subject is being
taken up by t h e URSI-G4 group. Checking with incohe rent
s catter observations is felt to be crucial for this task.
Concerning the Fl-point, a smoother transition from the
condition "Fl- present" to the condition "Fl - not- present" is
desirable , t o avoid abrupt changes in altitudinal , diurnal and
latitudinal variations. Gonzale s and Radice lla presented a
simple formula for the Fl h e ight which depends on foFl and o n
magnetic d ip; ch ecking with g l oba 1 data is necessary .
Concerning Gulyaeva' s half -de nsity-poi nt, data are needed to
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