The 1994 IRI meeting was part of the 30th General Assembly of the Committee on Space Research (COSPAR) that took place in Hamburg, FRG from July 11 to 21. The meeting had 10 well-attended sessions including 9 invited papers, 17 contributed papers, and 10 posters. The sessions titles were: Data for High-Latitude Modeling, Results from Theoretical Models at High Latitudes, Mapping of Ionospheric Characteristics, Storm-time Updating and Indices, D-Region, High-Latitude Plasma Temperatures and Ion composition, IRI Comparisons, Improvements and Usage, Posters, and Final Discussion.
Presentations at this workshop underlined the complex variation patterns and dependencies of ionospheric parameters in the high-latitude ionosphere. It is clear that a different treatment has to be chosen for this part of the globe. Regional mapping, storm-time updating and introduction of auroral boundaries and characteristics are needed to bring IRI closer to real conditions. As a result of the presentations and final discussions the following improvements will be introduced into IRI. [Responsible task members are listed in parentheses]
Auroral oval boundaries:
In his workshop presentation, D. Bilitza (GSFC/HSTX) reviewed the existing
models for the
description of auroral oval boundaries. Following his recommendation, it was
decided to
introduce auroral boundaries into IRI in the form of the Holzworth & Meng (1975)
parameterization of the Feldstein (1963) auroral ovals using corrected
geomagnetic
(CGM) coordinates. Magnetic activity is characterised through the 15-min Q
index; the
correlation between Q and Kp will be explored to help IRI users who prefer the
more
traditional Kp index. Besides its simplicity, the HMF model has the added
advandage that
it can be easily updated with measured boundary values where and when available.
Auroral
boundaries can be also defined through the level of precipitating particle flux.
Models
based on DMSP (Hardy et al., 1987) and NOAA/TIROS (Fuller-Rowell and Evans,
1987) particle
data were also discussed. They could provide the framework for future
improvements of IRI.
At the present stage the auroral boundary model in IRI will have the primary
function of
alerting users to the increased variability that can be expected within the
auroral oval.
[Bilitza; Bradley (U.K) will provide CGM related software]
Polar ionization tongue, ionization hole and patches:
R. Schunk (USU, USA), D. Anderson (AFPL, USA) and D. Rees (UK) reported about
their respective
modelling efforts at high latitudes and implications for IRI. The high-latitude
digisonde
database was reviewed by B. Reinisch (ULCAR, USA). D. McEwen (Canada) presented
observations
of F layer patches and their convection over the polar cap. Schunk suggested
that IRI should
include mathematical parameterizations of the typical ionization features that
are observed
(and theoretically modelled) in the high-latitude ionosphere, e.g. the
ionization tongue and
hole, and the polar patches, even though the actual location, amplitude, and
movement of these
features are still fare from being predictable at this time. As a first step
towards this goal,
it was decided to follow a recommendation by D. Anderson and include his
Parameterized Ionosphere
Model (PIM) as a special high-latitude option in IRI; PIM is a physical-based
model that includes
the typical high-latitude ionization features; with real-time data input this
model becomes part
of the Parameterized Real-time Ionosphere Specification Model (PRISM). [Anderson
will provide PIM code]
Storm-time updating:
P. Kishcha discussed the analytical updating procedure that was developed by him
and his
colleagues at IZMIRAN (Moscow, Russia). The algorithm describes the ionospheric
effects of
magnetic storms and substorms on foF2 and hmf2 based on ionosonde data for 380
storm events.
It provides the delta-foF2 and -hmF2 in terms of time since storm onset,
AE-index, solar activity,
season, local time and geomagnetic latitude. It was decided to include the
present version of the
IZMIRAN model in IRI to allow storm-time updating at subauroral latitudes.
[Kishcha will provide
updating code]
D-region
The three prime IRI D-region modelling teams reported about their progress and
results
(A. Danilov, Russia; M. Friedrich, Austria; W. Singer, FRG). As a result of
discussions at
this meeting two new options will be introduced into IRI. The representation of
the mid- and
low-latitude D-region electron density in terms of neutral density developed by
Friedrich and Tokar
(1992) for users who have access to the required neutral densities. With the
auroral updating as
proposed by Friedrich during this workshop an extension to high-latitudes is
possible; the auroral
component depends on measured riometer absorption as input parameter. Another
new option for mid-
and low-latitudes will be the D-region model developed by A. Danilov (Russia)
and his colleagues
that allows the user to specify conditions of winter anomaly or stratospheric
warming. Both models
include also a specification of the transition height between molecular and
cluster ions which will
be useful for the IRI ion composition model. Merging the two D-region rocket
data compilation
(Friedrich's and Danilov's) into one joint D-region model for IRI is an
important future goal
of the working teams. [Friedrich and Danilov will provide their model codes]
Presentations about ongoing IRI-related efforts
K. Oyama and his team at ISAS, Japan are continuing their efforts concerning the
modeling of the
topside plasma temperatures with the help of their OHZORA and AKEBONO in-situ
probe data. Oyama
presented temperature profiles up to plasmaspheric heights for different
high-latitude ranges and
times. This group is also working on improved global maps at 600 km. [Oyama]
In two invited talks by K. Schlegel (MPAe, FRG) and P.Collis (EISCAT) the potential of the EISCAT data base for ionospheric modeling and IRI was highlighted. EISCAT data will be the basis for a IRI improvement study in the high-latitude E-region. Initiated by K. Schlegel, this investigation will consider electron density as well as plasma temperatures.[Schlegel]
Work continues on developing a better representation for the half-density point (G-factor) at low latitudes based on digisonde observations, incoherent scatter data, and theoretical results [Reinisch (ULCAR,USA), Mahajan (NPL, India), Anderson (AFPL, USA)]
J. Grebowsky explained the GSFC comprehensive ion mass spectrometer data base (1964-84) that he and his colleagues at Goddard Space Flight Center have compiled. He discussed its potential for scientific studies and for a better representation of the IRI ion composition model in the lower ionosphere. [Grebowsky, Hoegy, Bilitza]
F1-region task force activity at ICTP
During the Final Discussion session a brief report was given about the F1-Region
Task Force
Activity that took place at the Atmospheric Physics and Radio-propagation
Laboratory (APRL)
of the International Center for Theoretical Physics (ICTP) in Trieste, Italy in
the weeks just
preceding the IRI-COSPAR meeting. The APRL Director S. Radicella had invited a
dozen scientists
(a majority from developing countries) to discus the identification and
deduction of F1-region
parameters from ionograms and the global mapping of these parameters. The
innovative format of
bringing together data providers and modelers in front of computer terminals and
informal
round-table discussions was highly successful and result in several
recommendations for
improvements of the IRI model and for ionogram data reduction in general. The
IRI group
strongly endorsed the ICTP/APRL activity and encouraged a continuation and
possible expansion
of this interesting activity in the coming years.
IRI Meetings, Publications and New Members
The first issue of the IRI Newsletter was published and distributed in June.
Contribution
and requests should be send to the editor K. Oyama (IRI Vice-chair). Ludmila
Triskova from
the Institute of Atmospheric Physics in Prague, Czech Republic was elected as
new working group
member. The papers of the 1992 and 1993 IRI Workshops were published in Advances
in Space Research,
Volume 14, Number 12 and Volume 15, Number 2, respectively. The next IRI
meeting will be held at
the National Physical Laboratory in New Dehli, India from January 9 to 13, 1995.
It will focus on
"Low and Equatorial Latitudes in IRI". The IRI group proposed a 1-day session on
"Quantitative
Descriptions of Ionospheric Storm Effects" for the 1996 COSPAR meeting in
Birmingham, U.K. and
jointly with C.2 a 2-day session on "E- and D-Region Physics and Modeling".
Back to IRI workshops page Back to IRI homepage