Bernese GPS Software Version 5.0 - Bernese GNSS Software

12. Ionosphere Modeling and Estimation
Figure 12.6: Options for IONEST.
sub-sections because IONEST always takes all available observations. This can be done
either on RINEX level (program CCRINEXO, ”Menu>RINEX>Cut/concatenate RINEX files>Observation
files”) or on Bernese-binary-format level (program OBSSPL, ”Menu>Service>Bernese observation files
>Split observation files”). Furthermore, you have to combine the individual ionosphere model
files created into one common file (see example in Figure 12.7). For longer sessions (e. g.,
24-hour sessions), it is much easier to generate a regional ionosphere model than a local one.
Please note that the estimation of local ionosphere models using the program GPSEST is
not recommended, since this possibility is not menu-supported. In addition, you would have
to prepare in a previous step the header of the ionosphere file to be introduced in GPSEST
(see also Section 22.9.4).
The estimated ionosphere models may be used in further processing steps, therefore it makes
sense to specify a filename at “Ionosphere model”. The ionosphere files (default extension ION)
are stored in the campaign-specific ATM directory. It is recommended to create a “Residuals”
(default extension RES) containing L4 residuals, if you wish to study short-term TEC
variations like scintillations or Traveling Ionospheric Disturbances (TIDs). Use the program
REDISP (”Menu>Service>Residual files>Display residual file”) to browse through these files.
In panel “IONEST 2: Options” (Figure 12.6), you may define some preprocessing options
to mark outliers when processing code measurements, or, to set up a new ambiguity
parameter B4 (according to observation equation, Eqn. (12.10)) for each cycle slip detected
when processing phase measurements. The model-specific options include
“Elevation cutoff angle”, the minimum elevation to be processed,
“Height of the single layer”, the single-layer height H (see mapping function in Eqn. (12.8)
and Figure 12.3),
“Degree of development in latitude” and “Degree of development in hour angle”, nmax and mmax of
the TEC representation displayed in Eqn. (12.11), and
“Maximum degree in mixed coefficients”, the maximal allowed sum (n + m) of both indices of
the TEC parameters Enm to be set up.
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