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Data Product Descriptions

hmi.V_avg120

Data Series Class: Data Means
Creating Module: datavg
Input Data: hmi.V_45s

Data Processing Status

Versions of creating module used to produce records in the data series:

The following records have been subsequently reprocessed and exist in multiple versions in the DRMS database:

For data notes applicable to reprocessed records, see below.

Data Notes

The fixed arguments to datavg used in populating this series are:

Records created with versions of datavg less than 1.2 (i.e. before CR 2126) lack Log segments recording textual information about the input records. They also lack any information in the HISTORY keyword of the calling arguments for the datavg module.

Records prior to CR 2128:060 were created from observable records that were processed using a different calibration version from those subsequently, and the resulting averages are detectably affected, particularly in the gradients. The record for 2128:120 mixes differently calibrated Dopplergrams about half and half, and that for 2128:060 to a small extent (about 12%).

The standard ring-diagrams pipeline uses the default values for arguments pa and dpa to datavg, 180.0 and 1.0 respectively. Thus, at times when SDO is rotated from its normal position by more than a degree, the corresponding Dopplergrams will be rejected. This may result in a substantial number of missing records and a consequent possible asymmetry in the effective time and corresponding metadata for the averaged records. (Of course this can also happen when large numbers of records are either missing or rejected for reasons of unacceptable quality as well.) The following records have been substantially affected (difference between target (MidTime) and effective time (T_OBS) greater than 4 hours):

*Note that MidTime is not recorded in records produced with versions of datavg less than 1.1; these MidTime values are estimated.

Because the length of the sampling interval is based on Carrington longitude, the number of constituent records varies with time of year. It ordinarily ranges between 15,852 and 17,494 45-sec records, corresponding to a temporal duration between 8.25625 and 9.11146 day. There are a few exceptions when the averaging was performed from incomplete record sets. These should only occur at the beginning (or end) of mission,. The following records are exceptional (excluding reprocessed records):

A Data Scaling Issue

With the current values of the FITS scaling parameters, there is a substantial ring of NaN values in the power segment near the solar limb, but well within the crop radius. These are due to RMS values that would exceed the representable range in 16-bit unsigned values with the chosen scaling parameter. Since CR 2111, the number of such out-of-range power values per image has varied between 26,000 and 73,000, with a mean of 57,350. The range of radii with valid means but invalid power due to scaling has been 0.9985–1.0495 (during CR 2126–2200). A value of 15.0 would reduce the number of unscaleable values by a factor of four, and a value of 30.0 would reduce it by a factor of 10, to about the same as the current number of unscaleable values for the mean.

There are also occasionally a few values of the mean segment that are out of scaling range, although always just beyond the nominal solar limb. These occur in the following records (typically, those around time of perihelion, but with a few near aphelion as well):

Records using subsequently reprocessed data as input

In certain cases, individual Dopplergrams from which the averages are computed were reprocessed after the averaging took place. In most, but not all cases, the reprocessing involved no actual changes to the data. Records in this series possibly affected are:

Notes on subsequently reprocessed or updated records

These notes apply only to data in records which have been subsequently reprocessed or updated, so are relevant for anything which may have made use of those data prior to their updates or replacement.

Data for CR 2096:240–2125:060 (1 May 2010 – 14 July 2012) were processed from observable records that included a camera position angle that was subsequently established to be about 0°.07 in error and corrected. Although this does not affect the image data themselves, which are averaged by pixel, the average values of CROTA2 in the keywords for the affected records needed to be suitably adjusted. This adjustment was made in all affected records between 4 and 8 October, 2018. At the same time, certain other keywords whose setting had been established or modified by changes to the datavg module in Version 1.0 were updated. Records that had been subsequently reprocessed were not updated.

Records created with versions of datavg less than 1.0 (i.e. before CR 2116) lacked valid values of keyword CRLN_OBS, and may lack valid values of keywords CRLT_OBS, RSUN_OBS, and DSUN_OBS as well; hence they cannot be used as input to mapping routines. (Setting of CRLT_OBS etc. began in June 2011, with CR 2110:240.) Of course the values of the associated standard deviation keywords D_CRLN_OBS etc. were also missing in the affected records. Records created with versions of datavg less than 1.0 may also have lacked valid values of keywords T_FIRST, T_LAST, and MidTime. Also, for records created with versions less than 1.2, the values of T_FIRST and T_LAST, if present, referred to the T_OBS, rather than T_REC, of the first and last contributing Dopplergrams. All of these differences have been removed, except for records which had already been reprocessed prior to 2018.10.08.

Prior to 18 Jan 2011, the values of mscale and pscale used were 5.0 and 0.008 respectively, rather than 0.25 and 10.0. The records affected are in the time range CR 2100:300 – 2102:060, all originally processed with v 0.8. The data for these records consequently have far greater range with correspondingly less precision than the remaining data. Furthermore, the segments representing per-pixel variance (power) were set with a different value of BITPIX from the standard subsequently set, and are currently (JSOC Release 9.2) unreadable with the DRMS drms_segment_read() function, although they are valid FITS files.

JSOC Series Definition

#=====General Series Information=====
Seriesname:      	hmi.V_avg120
Description:		"Temporal averages of HMI Vgrams over 1/3 CR"
Author:          	"Rick Bogart"
Archive:         	1
Unitsize:		1
Retention:       	1800
Tapegroup:       	1
PrimeKeys:       	CarrRot, CMLon

#=====Links=====

#=====Keywords=====

Keyword: CarrRot,  int,    variable, record, -1,  %d,     "", "Carrington rotation at MidTime"
Keyword: CMLon,    float,  slot,     record, 360, %03.0f, deg, "Longitude of central meridian at MidTime"

Keyword: CRPIX1,   float,  variable, record, NaN, %.3f, pixel, "Average WCS reference pixel location"
Keyword: D_CRPIX1, float,  variable, record, NaN, %.3f, pixel, "RMS of  WCS reference pixel location"
Keyword: CRPIX2,   float,  variable, record, NaN, %.3f, pixel, "Average WCS reference pixel location"
Keyword: D_CRPIX2, float,  variable, record, NaN, %.3f, pixel, "RMS of  WCS reference pixel location"
Keyword: CDELT1,   float,  variable, record, NaN, %.6f, arcsec/pixel, "Average WCS coordinate increment at reference point"
Keyword: D_CDELT1, float,  variable, record, NaN, %.6f, arcsec/pixel, "RMS of  WCS coordinate increment at reference point"
Keyword: CDELT2,   float,  variable, record, NaN, %.6f, arcsec/pixel, "Average WCS coordinate increment at reference point"
Keyword: D_CDELT2, float,  variable, record, NaN, %.6f, arcsec/pixel, "RMS of  WCS coordinate increment at reference point"
Keyword: CROTA2,   float,  variable, record, NaN, %.3f, deg, "Average WCS rotational angle"
Keyword: D_CROTA2, float,  variable, record, NaN, %.3f, deg, "RMS of  WCS rotational angle"
Keyword: T_OBS,    time,   variable, record, JD_0, -1, TAI, "Average of observation time"
Keyword: D_T_OBS,  float,  variable, record, NaN, %.0f, s, "RMS of observation time"
Keyword: MidTime,  time,   variable, record, JD_0, -1,  TAI, "Midpoint of averaging interval"
Keyword: DataRecs, int,    variable, record, 0, %d, NA, "Number of valid input records"
Keyword: MissRecs, int,    variable, record, 0, %d, NA, "Number of skipped input records"
Keyword: Quality,  int,    variable, record, 0x00000000, %08x, NA, "Data Quality flag"
Keyword: MeanMIN,  float,  variable, record, nan, %.1f, m/s, "Minimum value in Mean image"
Keyword: MeanMAX,  float,  variable, record, nan, %.1f, m/s, "Maximum value in Mean image"
Keyword: MeanAVG,  float,  variable, record, nan, %.2f, m/s, "Mean value of Mean image"
Keyword: MeanRMS,  float,  variable, record, nan, %.2f, m/s, "RMS value of Mean image"
Keyword: MeanSKEW, float,  variable, record, nan, %.3f, "", "Skewness of Mean image values"
Keyword: MeanKURT, float,  variable, record, nan, %.3f, "", "Kurtosis (of Mean image values"
Keyword: PowrMIN,  float,  variable, record, nan, %.3e, m2/s2, "Minimum value in Power image"
Keyword: PowrMAX,  float,  variable, record, nan, %.3e, m2/s2, "Maximum value in Power image"
Keyword: PowrAVG,  float,  variable, record, nan, %.3e, m2/s2, "Mean value of Power image"
Keyword: PowrRMS,  float,  variable, record, nan, %.3e, m2/s2, "RMS value of Power image"
Keyword: PowrSKEW, float,  variable, record, nan, %.3f, "", "Skewness of Power image values"
Keyword: PowrKURT, float,  variable, record, nan, %.3f, "", "Kurtosis (of Power image values"
Keyword: CountMIN, int,    variable, record, -1, %d, "", "Minimum value in Count image"
Keyword: CountMAX, int,    variable, record, -1, %d, "", "Maximum value in Count image"
Keyword: OBS_VR,   double, variable, record, NaN, %.3f, m/s, "Average observer heliocentric radial velocity"
Keyword: D_OBS_VR, double, variable, record, NaN, %.3f, m/s, "RMS of observer heliocentric radial velocity"
Keyword: OBS_VW,   double, variable, record, NaN, %.2f, m/s, "Average observer heliocentric westward in plane of Carrington equator velocity"
Keyword: D_OBS_VW, double, variable, record, NaN, %.2f, m/s, "RMS of observer heliocentric westward in plane of Carrington equator velocity"
Keyword: OBS_VN,   double, variable, record, NaN, %.3f, m/s, "Average observer heliocentric northward velocity wrt Carrington"
Keyword: D_OBS_VN, double, variable, record, NaN, %.3f, m/s, "RMS of observer heliocentric northward velocity wrt Carrington"
Keyword: DSUN_OBS, double, variable, record, NaN, %12.5e, m, "Average observer heliocentric distance"
Keyword: D_DSUN_OBS,double,variable, record, NaN, %12.5e, m, "RMS of observer heliocentric distance"
Keyword: CRLN_OBS, float,  variable, record, NaN, %.2f, deg, "Average observer Carrington longitude"
Keyword: D_CRLN_OBS, float,variable, record, NaN, %.2f, deg, "RMS of observer Carrington longitude"
Keyword: CRLT_OBS, float,  variable, record, NaN, %.2f, deg, "Average observer heliographic latitude"
Keyword: D_CRLT_OBS, float,variable, record, NaN, %.2f, deg, "RMS of observer heliographic latitude"
Keyword: RSUN_OBS, float,  variable, record, NaN, %.2f, arcsec, "Average solar angular radius"
Keyword: D_RSUN_OBS, float,variable, record, NaN, %.2f, arcsec, "RMS of solar angular radius"
Keyword: T_FIRST,  time,   variable, record, JD_0, 0, TAI, "Earliest time in input data"
Keyword: T_LAST,   time,   variable, record, JD_0, 0, TAI, "Latest time in input data"
Keyword: Module,   string, variable, record, "", %s, NA, "Creation module"
Keyword: BLD_VERS, string, variable, record, "", %s, NA, "JSOC library build version"
Keyword: Source,   string, variable, record, "", %s, NA, "Source DRMS data series"
Keyword: Input,    string, variable, record, "", %s, NA, "Input DRMS dataset specification"
Keyword: Created,  time,   variable, record, JD_0, -1, Z, "Record creation time"
Keyword: HISTORY,  string, variable, record, "", %s, NA, "Record modification history"

Keyword: WCSNAME,  string, constant, record, "Helioprojective-cartesian", %s, NA, "WCS name"
Keyword: WCSAXES,  int,    constant, record, 2, %d, "", "Number of WCS axes"
Keyword: CTYPE1,   string, constant, record, HPLN-TAN, %s, NA, "WCS axis type"
Keyword: CTYPE2,   string, constant, record, HPLT-TAN, %s, NA, "WCS axis type"
Keyword: CUNIT1,   string, constant, record, arcsec, %s, NA, "WCS axis units"
Keyword: CUNIT2,   string, constant, record, arcsec, %s, NA, "WCS axis units"
Keyword: CRVAL1,   float,  constant, record, 0.000, %.3f, arcsec, "WCS reference point value"
Keyword: CRVAL2,   float,  constant, record, 0.000, %.3f, arcsec, "WCS reference point value"
Keyword: Interval, float,  constant, record, 120.0, %.1f, deg, "Averaging interval in units of Carrington rotation"
Keyword: TELESCOP, string, constant, record, SDO/HMI, %s, NA, "Telescope used to acquire the data"
Keyword: WAVELNTH, float,  constant, record, 6173.0, %.1f, , "Observing wavelength"
Keyword: ORIGIN,   string, constant, record, "SDO/JSOC-SDP", %s, NA, "Organization creating the record"
Keyword: RSunRef,  float,  constant, record, 696.0, %.1f, Mm, "Reference value of solar radius"

# prime key slotting info (hidden)

Keyword: CMLon_base, float, constant, record, 360.0, %.1f, deg, "CMLon index base"
Keyword: CMLon_step, float, constant, record, -60.0, %.1f, deg, "CMLon index step"

#=====Segments=====

Data: mean,  variable, short, 2, 4096, 4096, m/s,   fits, "compress Rice", 0.0, 0.25, "Doppler mean"
Data: power, variable, short, 2, 4096, 4096, m2/s2, fits, "compress Rice", 327670.0,  10.0, "Doppler power"
Data: valid, variable, short, 2, 4096, 4096, NA,    fits, "", 32767.0, 1.0, "valid pixel count"
Data: Log,   variable, char, 0, NA, generic, "run log"


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