POLAN default options
POLAN has a comprehensive range of options to allow the true-height analysis to be
tailored completely to the users requirements. For a service based on
automatic provision of data and results, these parameters have to be set to
some sensible default values. These may not always produce the best results,
but will provide a consistent analysis of the data. Tools for a more
interactive user led analysis are available via the WDC or Ionosondes group at
RAL (Usage and Notes).
The various default options chosen are :-
- Gyrofrequency
at the ground - Taken from data file, set to negative value for constant value
in the analysis.
- Magnetic Dip angle -
Taken from the data file.
- Starting height - With START
set to 0, POLAN derives a starting height hs to use at 0.5Mhz, by
extrapolating the first few virtual height data points and limiting the result
to a reasonable range.
- Analysis mode -
Defaulted to 0, POLAN then uses the mode 5 analysis (changing to 15 at high
dip angles) which appears most suitable for general work.
- Valley - Set to 0 for most
routine calculations. POLAN then inserts between layers a valley selected from
the "standard" family. The width (km) and depth (MHz) of this valley depend on
the height of the underlying peak.
Other assumptions :-
- No critical frequencies specified - This stops POLAN trying to
calculate the profile past the peak.
- No Extraordinary (X) ray data is included. Good X-ray data can improve
the analysis slightly, but poor X-ray data can have serious consequences for
the quality of the analysis.
Ionosondes |
WDC
4-DEC-1997 Matthew Wild