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| == Methodology == Once localized sites that are magnetically active have been found (i.e., building on the full-disk active region masks) the HARP identification problem consists of two pieces: spatially grouping magnetic activity into objects on the scale of active regions, and tracking these objects from image to image. The grouping problem is harder, because flux emergence can cause formerly isolated ARs to merge. This means that a given HARP cannot be declared complete until it has disappeared in view of the observer, or rotated off the visible disk. Consequently, final HARPs are delayed by about a month. It is important to track HARPs up to the limb, so that all the history of the HARP can be taken in to account in making grouping decisions. Consequently, the grouping criterion takes the spherical geometry into account. The HARP identification component consists of two parts, a grouping/tracking component, implemented in Matlab, and a data ingestion component, implemented as a JSOC module. |
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| # SERIES INFO . DATANAME = HARP . RETENTION = 0 . ARCHIVE = 0 . PRIMEKEYS = HARP_ID, T_REC |
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| # PRIME KEY INFO . HARPID, INT . T_REC, TIME, Slotted . T_REC_STEP = 12MIN . T_REC_EPOCH = 1976.12.31_23:59:45.000_UTC # PATCH INFO . PNUM, link, "PNUM", patch - '' The patch number of the HARP at T_REC in the Patches_Found dataseries'' . AREA, link,"AREA", patch - '' The AREA keyword of the patch`` . I_MIN, link, "I_MIN", patch . FLUX, link,"FLUX",vecpatch - '' The computed flux of the vector field in the patch '' . BTOT, link, "BTOT", vecpatch . # OTHER information about the patches # SEGMENT INFO - links . data: arp_map, link, patch - '' Pointer to the bitmap of the patch '' . data: blos, link, patch - '' Pointer to pointer to line-of-sight magnetic field data '' . data: BTOT, link, vecpatch - '' Pointer to pointer to vector magnetic field data '' # LINKS . link: patch, "Patches_Found", static ''(because PNUM is arbitrary) '' . link: vecpatch, "Vector_Patches", dynamic === Related Data Series === |
== Related Data Series == |
HARP - HMI Active Region Patches
Overview
A HARP (short for HMI Active Region Patch) is a coherent magnetic structure at the scale of a solar active region identified in one or more HMI line-of-sight magnetograms. HARPs are typically observed over an extended time interval (e.g., days), and tracked from one image to the next.
The HARPs are in the data series hmi.MHARP_720s, which is indexed by an integer identifier, HARPNUM, and by T_REC. The HARP will often be linked with a NOAA Active Region. This data series provides pointers to information covering the entire disk passage for each HARP in the HMI catalog, as well as summary information (e.g., integrated flux over the HARP), for each HARPNUM at each T_REC. The data series contains one segment, MASK, which is a mask image of the extent of the HARP at a given time.
The HARPs are found by analyzing the active region masks in hmi.Marmask_720s. (The masks are in turn derived from hmi.M_720s and corresponding intensitygrams.) All three of these data products are full-disk images, in helioprojective-tangent coordinates (that is, as projected on the focal plane, and not remapped to a latitude-longitude system). The MASK segment of the HARP data series indicates exactly which pixels in the magnetogram are part of the HARP. It is a rectangular cutout from the full-disk images referred to above, typically several hundred pixels in each dimension, with special values indicating whether a pixel is on-HARP or not.
The data series can be used by following the links to associated vector, line-of-sight, and intensity data. For diagnostic or summary purposes, plots of individual keywords, such as integrated flux or size of the HARP, are also useful.
Methodology
Once localized sites that are magnetically active have been found (i.e., building on the full-disk active region masks) the HARP identification problem consists of two pieces: spatially grouping magnetic activity into objects on the scale of active regions, and tracking these objects from image to image. The grouping problem is harder, because flux emergence can cause formerly isolated ARs to merge. This means that a given HARP cannot be declared complete until it has disappeared in view of the observer, or rotated off the visible disk. Consequently, final HARPs are delayed by about a month.
It is important to track HARPs up to the limb, so that all the history of the HARP can be taken in to account in making grouping decisions. Consequently, the grouping criterion takes the spherical geometry into account.
The HARP identification component consists of two parts, a grouping/tracking component, implemented in Matlab, and a data ingestion component, implemented as a JSOC module.
Keywords