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HMI Ring Diagrams
Pipeline Module Specifications
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mtrack
Module Version
0.8 1 IX 2009
General Description
mtrack takes as its input a dataset of records representing solar
image data observed at a uniform temporal cadence, and produces as
its output a set of records representing mapped cubes at selected
heliographic coordinates, tracked at selected rates for the duration
of the input data interval. The tracked data cubes provide the input
to pspec3 and all subsequent ring-diagram analysis procedures; they
also provide input to the time-distance analysis pipeline and possibly
other local analysis procedures. They may also be used for animations.
Status
This version has been superseded by Version 0.9
Included in JSOC release 5.6 as mtrack
This version supersedes Version 0.7
The source code and Makefile are in the JSOC CVS repository
Usage
mtrack_v08 [-cnorvxGM] in= InputDescriptor out= OutputDescriptor
[param= val ...]
Flags
-c track at Carrington rate (a0 = a2 = a4 = merid_v = 0)
-n turn off tracking, just correct for any observer motion
(a0 = -2.8653291, a2 = a4 = merid_v = 0)
-o remove line-of-sight component of observer velocity from input data
not currently implemented
-r remove line-of-sight component of solar rotation from input data
not currently implemented
-v run verbose
-x experimental run (do not insert records in output series)
-G use GONG keywords for input; not currently implemented
-M use MDI keywords for input and correct for MDI distortion;
use of MDI keywords not currently implemented
Parameters
in either the name of an input data set (record selection)
or the name of an input data series; in the latter case,
tmid and length parameters must also be supplied.
segment the name of the data segment to be used as input;
required if the input data series has more than one data
segment per record, otherwise ignored
out the name of the output data series, which must already
exist; record selection is based on runtime parameters
and the series prime keywords
bckgn The file name of a background image to be subtracted
from the data for purposes of detrending. If no value
is supplied, no detrending is performed. The background
image must be in the same format as the images.
Detrending is performed before the images are mapped.
reject The name of a file containing a list of records in the
input data series to be rejected for various reasons.
This is a list that can be prepared supplementary to
whatever quality/rejection criteria may be contained in
the records. The format of this file is to be specified.
qmask not currently implemented
tmid The target midpoint of the tracking interval, which may
be expressed in either standard Date_Time format or in
CarringtonRotation:Longitude format, e.g. 1988:150.0
in which case it refers to the central meridian crossing
time appropriate to the observing platform.
Must be used in conjunction with the length parameter.
Ignored if the in value is a specific data recordset.
length
tstart The target starting time of the tracking interval, expressed
in standard Date_Time format. Must be used in conjunction with
the tstop parameter. Ignored if the in value is a specific
data recordset, or the tmid parameter is specified..
tstop The target ending time of the tracking interval, expressed
in standard Date_Time format. Must be used in conjunction with
the tstart parameter. Ignored if the in value is a specific
data recordset, or the tmid parameter is specified..
tstep The temporal cadence of the output tracked cubes,
in sec. If unspecified, defaults to the cadence of the
input series.
lat An array of heliographic latitudes (in degrees) of the
centers of regions at the midpoint of the tracking.
Default: [0.0] (If there is only one target,
the enclosing characters, which may be brackets, braces, or
parentheses, may be omitted. Target values are separated by
commas.) If there are more lon values than lat values,
the final lat value is replicated.
lon An array of heliographic longitudes (in degrees) of the
centers of regions at the midpoint of the tracking.
Default: [0.0] If there are more lat values than lon
values, the final lon value is replicated. Note that
the longitudes are Carrington, not Stonyhurst.
map The mapping projection option; recognized values are:
carree, Cassini, Mercator, cyleqa, sineqa, gnomonic,
Postel, stereographic, orthographic, and Lambert
Default: Postel. This parameter, along with all of the
succeeding ones, applies to all output regions.
interp not currently implemented
scale The scale of the tracked regions at map center, in
heliographic degrees per pixel. No default.
cols Number of columns in the output maps (pixels). Default: 0,
but at least one of cols and rows must be set non-zero; if
either is 0, it will be set to the value of the other, so
that the tracked region maps will be square.
rows Number of rows in the output maps (pixels). Default: 0;
see cols.
map_pa The position angle of heliographic north on the output
maps, measured westward (counter-clockwise), in deg.
Default: 0.
a0 The 0 order term in an expansion in sin^2 (latitude) of the
assumed rotation rate for tracking, minus the Carrington rate,
in μrad/sec. Default: -0.02893, which corresponds, along with
the defaults for a2 and a4, to the Snodgrass 1982/84 photospheric
Doppler rate. This parameter, along with a2, a4 and merid_v, is
ignored if either of the flags -c or -n is set.
a2 The 1st order term in the assumed rotation rate profile for
tracking.Default: -0.3441. See a0.
a4 The 2nd order term in the assumed rotation rate profile for
tracking .Default: -0.5037. See a0.
merid_v The assumed meridional velocity for tracking, in μrad/sec,
positive northward. Default: 0. See a0. Note that the
velocity in μrad/sec is about 0.0014368 times the meridional
rate in m/sec.
bscale The scaling to be applied to output data stored externally as
short integers to convert to floating-pont values. Default: 1.0
bzero The offset to be applied to output data stored externally as
short integers, after multiplication by bscale, to convert to
floating-pont values. Default: 0.0
trec_key The key name to be used for the prime key of the input data
series, assumed to be a slotted time series; Default: T_REC
tobs_key The key name to be used for the key value representing the
midpoint of the record observation times in the input data
series; Default: T_OBS
tstp_key The key name to be used for the key value representing the
trec_key step size in the input data series; Default: CADENCE
qual_key The key name for a 32-bit image quality field in the input data
series; Default: Quality.not currently implemented
clon_key The key name to be used for the key value representing the
observer Carrington longitude at the time of observation in
the input data series; Default: CRLN_OBS
clat_key The key name to be used for the key value representing the
observer heliographic latitude at the time of observation in
the input data series; Default: CRLT_OBS
crot_key The key name to be used for the key value representing the
observer Carrington rotation number at the time of observation
in the input data series; Default: CAR_ROT
Input Data series class:
slotted time series of solar image data
Input keys used or inspected:
TELESCOP, T_REC_index, trec_key*, tstp_key*, tobs_key*, clon_key*,
crot_key*, clat_key*, CUNIT1, CUNIT2, CDELT1, CDELT2, CRPIX1, CRPIX2,
R_SUN, OBS_ASD, CROTA2, S_MAJOR, S_MINOR, S_ANGLE
* specified as module argument
Sample input series:
mdi.fd_V_lev18
Output Data series class:
tracked mapped data cubes from solar image data
Output keys set (if possible):
WCSNAME, WCSAXES, CTYPE1, CTYPE2, CTYPE3, CUNIT1, CUNIT2, CUNIT3,
CRPIX1, CRPIX2, CRPIX3, CRVAL1, CRVAL2, CRVAL3, CDELT1, CDELT2, CDELT3,
LonHG, LatHG, MapProj, Interp, MidTime, CarrTime, CarrRot, CMLon, CarrLon,
LonCM, T_START, T_STOP, LonSpan, Coverage, ZonalTrk, MeridTrk, Module,
Source, Input, Backgrnd, RejectList, MapScale, Duration, Width, Height,
PosAng, PrimeKeyString
Input keys propagated to output (if possible):
none
Sample output series:
mdi.rdVtrack_dp
Sample command:
mtrack_v08 -v in= mdi.fd_V_lev18 out= mdi.rdVtrack_dp \
tmid= 1988:180.0 length= 1664 cols= 128 rows= 128 scale= 0.125 \
bckgn= ~rick/avgs/vel/mdi/lev15/1988/1988:180/mean.fits \
reject = ~rick/soi/qual/reject.fd_V_01h \
lat= "{-30.0, -22.5, -15.0, -7.5, 0.0, 7.5, 15.0, 22.5, 30.0}" \
lon= "{150.0, 157.5, 165.0, 172.5, 180.0, 187.5, 195.0, 202.5, 210.0}"
Testing
Bugs in current version
Checks for validity of tstart and tstop parameters are unreliable, due
to bugs in DRMS treatment of scans of invalid strings for times
(ticket #177)
Should free log, map
There appear to be bugs in cmdparams parse_array: see comments in v0.7
for valgrind report
Will not accept an input dataset specification of @*
The image foreshortening corrections are appropriate for 1 AU, independent
of DSUN_OBS
The input of the ellipse position angle has not been verified, but then
neither has the correction for ellipticity of the image altogether
If there are multiple data segments of rank 3 in the output series, a
warning is generated and the first one is used
The protocol of the Log segment, if present in the output series, is not
verified to be generic
There is no verification that numerous essential key data are actually
in the input dataset, in particular trec_key, tobs_key, clon_key,
clat_key, and crot_key.
Uses private local FITS code rather than cfitsio for reading in
background image
When a target time and length are given, the actual number of records
may differ by one from the expected number; this only occurs if
the target time differs by a small but non-zero amount (< 0.1 sec)
from either the data record time or the midway point between data
record times. This happens for example, if the length is odd and
the target time differs from an actual observation time by more than
0.1 usec but less than 0.05 sec, with a 1-minute cadence
The input data are unconditionally read in as floats (single-precision),
and the output data written as scaled shorts.
There is evidently no WCS conventional name for the Cassini-Soldner
(transverse plate carree) projection; CAS is arbitrarily used; the
alternative would be to interchange HGLT and HGLN, but that would
necessitate a change in the position angle
The keyword unit for "Duration" in the output series is ignored, and
assumed to be "sec"; there are probably a few other keywords for which
there is a similar issue.
The use of drms_segment_write() to enable CFITSIO compression requires
significant dynamic memory allocation (see notes on differences from
fastrack below) and effectively limits the number of output cubes that
can be produced in a single run. For the JSOC cluster, the limit is
equivalent to about sixteen 256*256*4096 cubes. Use of the
drms_segment_writeslice() function to remove this restriction awaits
DRMS fixes.
Changes from Previous Version
added keywords for output cadence, start/stop specification,
interpolation option
extensive modifications to allow for time interpolation to different
cadence from input, missing records and non-uniformly spaced records
in input
removed restriction on output segment name
added correction for MDI image distortion and PA and image center
(with -M flag), but not yet correction for plate scale if necessary
added processing of personal MDI image quality rejection lists
added setting of optional PrimeKeyString
adjust midtime to phase of input when specified as CR:CL
Key Differences from fastrack
The input and output data must be in DRMS data series rather than DSDS
data sets.
The target locations are calculated for the midpoint of the tracking
interval, not the start.
In order to support compression of the output FITS data cubes using the
DRMS API, the cubes must be retained in memory until completion of all
input, rather than having time slices appended as the input records are
processed. This requires significant dynamic memory allocation for long
time series of many large tracked cubes The storage savings resulting
from compression is in the range 33.1 — 37.4% for typical MDI Doppler
dense-pack data cubes.