NAME
cornymmik - calculates revised cutoff rigidity due to Nymmik et al
USAGE
cornymmik infile outfile corcol kpcol localtimecol
DESCRIPTION
cornymmik calculates a revised or corrected cut off rigidity (COR)
value as described by Nymmik et al. 2009 (Nymmik hereafter). This
method accounts for geomagnetic disturbances that are not handled by
typical COR values calculated by static magnetic field maps (such as
by prefilter).
The Nymmik technique uses the geomagnetic planetary Kp index as a
proxy for geomagnetic disturbances. It assumes the Tsyganenko-89
geomagnetic disturbance model, which is parameterized by Kp. The
research paper does full particle tracing in the geomagnetosphere.
Since the geomagnetic model depends on local solar time, the results
depend on local time as well. The result of the Nymmik work is an
easily parameterized model for an adjusted cut off rigidity value.
The input must be a FITS binary table, which contains the following columns
- baseline cut-off ridigity - the table must already contain a baseline
cut off rigidity, which can be calculated by (say) prefilter. The name
of this column is given by the corcol parameter, which defaults to COR_SAX.
It is not recommended to use prefilter's COR_ASCA output.
- Kp value - the planetary Kp index must be present. Analysts may
use the task geomagterp (and its associated geomagnetic CALDB tables)
to retrieve this value. The name of this column is given by the
kpcol parameter, which defaults to KP.
- localtimecol - the local solar time at the position of interest
(in degrees). The prefilter output, LOCAL_TIME, may be used for this
input. The name of this column is given by the localtimecol
parameter, which defaults to LOCAL_TIME.
While the inputs described above are listed as "column names," in fact
any compatible CFITSIO calculator expression can be used. For
example, localtimecol="LOCAL_TIME" would indicate to use the column
named "LOCAL_TIME", but localtimecol="(LOCAL_TIME_HOURS*15)" would
indicate to use an on-the-fly calculated expression which is 15
multiplied by the local time in hours (to get the required degrees).
The output is stored in a column named by the parameter outcol, which defaults
to "COR_NYM".
The output file may be a new FITS file, or if outfile=INFILE, the
input file will be replaced with the revised table (assuming
clobber=YES).
PARAMETERS
- infile [filename]
- Name of the input file containing the required columns.
- outfile [filename]
- Name of the output file, where the revised input table is to be placed.
If outfile=INFILE then the input file is modified in place. NOTE that if
the requested column name is already present in the output, then it will
not be deleted, and instead the quantities in that column will be adjusted.
- corcol [string]
- Name of the input COR column, or suitable CFITSIO calculator expression, as
described above.
- kpcol [string]
- Name of the input Kp column, or suitable CFITSIO calculator expression, as
described above.
- localtimecol [string]
- Name of the input local time column, or suitable CFITSIO calculator expression, as
described above.
- (outcol = "COR_NYM") [string]
- Name of the output revised COR column, or suitable CFITSIO calculator expression, as
described above.
- (cleanup=YES) [boolean]
- If YES, then clean up temporary files. If NO, then temporary
files are preserved.
- (clobber = NO) [boolean]
- If outname already exists, then "clobber = yes" will overwrite it.
- (history = yes) [boolean]
- If set, HISTORY keywords are written to output.
- (chatter = 1) [integer, 0 - 5]
- Controls the amount of informative text written to standard output.
Setting chatter = 5 will produce detailed diagnostic output, otherwise
this task normally does not write any output.
EXAMPLES
1. Execute cornymmik prompting the user for parameter values.
cornymmik
2. Execute cornymmik on filter.mkf, modifying in place.
cornymmik filter.mkf INFILE COR_SAX KP LOCAL_TIME clobber=YES
SEE ALSO
LAST MODIFIED
December 2020
REFERENCES