[IGSMAIL-2311] Solar eclipse on 11 August 1999.

[Dr.]

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IGS Electronic Mail      Fri Jun 18  7:22:24 PDT 1999      Message Number 2311
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Author: Dr. Joachim Feltens
Subject: Solar eclipse on 11 August 1999.

subject: Solar eclipse on 11 August 1999.

Dr. Joachim Feltens                                 Darmstadt, 17 June 1999
IGS Ionosphere Working Group Chairman
EDS at ESOC-FDD
Robert-Bosch-Strasse 5
D-64293 Darmstadt
GERMANY



Subject: Solar eclipse on 11 August 1999.



Dear IGS colleagues, dear colleagues from the ground stations,


beyond the Working Group's pilot phase activities (routine production of
ionospheric Total Electron Content (TEC) maps & GPS satellite Differential
Code Biases (DCBs)), good contacts are maintained to the ionosphere
scientific community to support each other, to exchange ideas, etc.

The upcoming solar eclipse on 11 August 1999 is a unique opportunity for
the ionosphere community to study the behavior of the ionosphere: For a
time of a few hours solar radiation is switched off. A considerable de-
crease in TEC as well as some side effects (like gravity waves in the atmo-
sphere and travelling ionospheric disturbances (TIDs)) can be expected. The
ionosphere scientists are thus looking very hopeful to this event, and try-
ing to collect as much observation data as possible from different sources.
One source are of course the GPS (and perhaps GLONASS) dual-frequency trak-
king data that are routinely collected at the IGS sites. A lot of phenomena
expected to happen in the ionosphere will be short-lived (like travelling
wave structures) and cannot be extracted with the standard 30 sec sampling
rate of IGS RINEX files. A 1 sec sampling rate is therefore appreciated.

According to The Astronomical Alamanc 1999, page A86, the solar eclipse
will be between 09:00 and 13:00 UT on August 11. The zone of totality will
mainly be seen over Europe (where the IGS stations net is dense), but also
at the east coast of North America and in the East along the Kaukasus
mountains and as far as to the East of India.

As part of the mutual support between the Iono_WG and the ionosphere com-
munity I may ask you whether you would be ready to make, from 11/08/99
00:00 UT until 11/08/99 24:00 UT an enhanced tracking of GPS (and GLONASS)
with a sampling rate of 1 sec and to deliver these RINEX files to the CDDIS
data centre ? I know that there might be space problems in the receivers at
such a high sampling rate. So lower sampling rates are o.k. also, if neces-
sary. If lower sampling rates will be chosen there is the following con-
dition: 30 sec divided by the sampling rate must be an integer, i.e. pos-
sible sampling rates are : 1, 2, 3, 5, 6, 10, 15 sec. 30 sec is the
standard IGS sampling rate.

According to my colleague Carlos Garcia, who handles our ESOC receivers,
two kind of RINEX files should then be created for this day from the high
sampling rate data: 1) standard 30 sec RINEX files for the IGS and
2) RINEX files with the full sampling rate for the ionosphere. According to
Carlos it is recommended to make prior to the solar eclipse at test run of
one hour or so with the high sampling rate to see how the receivers behave.

The tracking data should then be delivered to the CDDIS data center:

    ==> Mrs. Carey Noll from CDDIS will tell us a directory name soon.

I am looking forward to hear your answers on my request and hope for a
vivacious participation of IGS stations to that campaign. But also GPS and
GLONASS data from non-IGS stations is very welcome.


Best regards           Joachim Feltens



[Mailed From: jfeltens at esoc.esa.de]