Differences between revisions 1 and 53 (spanning 52 versions)
⇤ ← Revision 1 as of 2009-04-03 16:26:48 →
Size: 1612
Editor: pool-71-105-100-82
Comment:
← Revision 53 as of 2014-11-18 05:17:51 → ⇥
Size: 12933
Editor: ToddHoeksema
Comment:
Deletions are marked like this. Additions are marked like this.
Line 1: Line 1:
== HMI Magnetic Field Products == = HMI Magnetic Field Products =
||<style="text-align:center" |6> {{http://jsoc.stanford.edu/data/hmi/images/latest/HMI_latest_Mag_256x256.gif}} ||Four basic types of magnetic field products are described below. ||
||Some data products suitable for space weather applications are available in near real time (''nrt''). Such data products always have ''nrt'' in the series name. ||
||More details are provided at LineofsightMagneticField, VectorMagneticField, SynopticMaps, [[HARPDataSeries]], [[http://jsoc.stanford.edu/doc/data/hmi/sharp/sharp.htm|SHARPs]], and SpaceWeatherProducts. ||
||Quick access to HMI magnetic field catalogs and data products can be found at http://hmi.stanford.edu/magnetic ||
||Notes for users of HMI Magnetic field pipeline data can be found at PipelineCode ||
||Available vector field papers for reference: [[http://link.springer.com/article/10.1007/s11207-014-0516-8|Vector Field Pipeline Overview]] [[http://link.springer.com/article/10.1007/s11207-014-0497-7|VFISV ME inversion]] [[http://link.springer.com/article/10.1007/s11207-014-0529-3|SHARP]] ||
Line 3: Line 9:
Line-of-sight magnetic field will be computed from Doppler Velocity in two polarizations, as is done for MDI.
Line 5: Line 10:
Vector Field will be computed from Stokes parameters derived from an independent set of polarized filtergrams.

After launch the possibility of combining the two cameras will be explored.

The basic line-of-sight cadence is 45 seconds. The basic vector field cadence in 90 seconds.

Vector field data products will be the following quantities and uncertainties on each
 . |B| - total flux
 . Filling factor
 . Inclination (gamma) to the line of sight
 . Azimuth (relative to solar north
 . Magnetic line-of sight velocity		 ===== Line-of-sight Magnetograms =====
 . LineofsightMagneticField : The line-of-sight magnetic field, hmi.M_*, is computed from the difference of the Doppler velocities observed in two circular polarizations, as was done for MDI. The fastest line-of-sight observing cadence is 45 seconds ([[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.M_720s|hmi.M_45s]]) in which twelve 4096*4096 filtergrams from the HMI Doppler camera are combined, one in each circular polarization at each of six wavelengths. A lower noise version ([[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.M_720s|hmi.M_720s]]) is calculated every 720s using selected filtergrams from nine 135s vector field sequences from the other HMI camera.
 . The latest nrt HMI images are available at http://jsoc.stanford.edu/data/hmi/images/latest/.
 . A browsable image catalog of[[http://hmi.stanford.edu/data/hmiimage.html|HMI magnetic field and intensity]]
 . [[http://jsoc.stanford.edu/data/hmi/images/latest/HMI_latest_color_Mag_1024x1024.jpg|Colorized magnetograms]] use the IDL-compatible [[http://jsoc.stanford.edu/data/hmi/HMI.MagColor.IDL_256.lut|color table]]. The [[http://jsoc.stanford.edu/data/hmi/MagColors0.jpg|color map]] is [[http://jsoc.stanford.edu/data/hmi/HMI_M.ColorTable.pdf|explained in more detail here]].
Line 20: Line 18:
===== Module Inputs =====
 . List inputs here		 ===== Vector Magnetic Field Image Data =====
Line 23: Line 20:
===== Module Outputs =====
 . List outputs here		  . VectorMagneticField : The vector magnetic field is computed from Stokes parameters derived from an independent set of polarized filtergrams. The basic vector field observing cadence is 135 seconds and uses images from HMI's Magnetic camera. The 36 filtergrams measure six polarization states, I plus or minus Q,U,and V, at six fixed wavelengths. All filtergrams are corrected for instrumental effects and interpolated to the proper time. Most analysis is done with weighted averages computed every 720s using data collected over 1215 seconds (nine 135s intervals). The processing happens in three steps. First Stokes parameters ([[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.S_720s|hmi.S_720s]]) are computed from level 1 filtergrams. Then a Milne-Eddington inversion is performed to determine the field and other plasma parameters ([[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.ME_720s_fd10|hmi.ME_720s_fd10]]). Finally disambiguation is performed to determine the field azimuth angle See [[http://link.springer.com/article/10.1007/s11207-014-0516-8|Vector Field Pipeline Overview]] for a description.
Line 26: Line 22:
===== Cadence =====
 . Indicate nominal cadence on which module is run		  . FullDiskDisamb : Full-disk disambiguated vector magnetic field images are available every 12 minutes starting on 19 December 2013 and can be found at [[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.B_720s|hmi.B_720s]]. Magnetograms for earlier times can be computed upon request. These full disk disambiguation results are used to produce SHARPs starting on Jan 15, 2014.
Line 29: Line 24:
===== Archive =====
 . Indicate if/when products are archived		  . Vector Field in HMI Active Region Patches : ([[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_720s|hmi.sharp_720s]], [[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_cea_720s|hmi.sharp_cea_720s]] )
Line 32: Line 26:
===== Options =====
 . Indicate if there are any options when running the code
Line 35: Line 27:
===== Overall Status of Module =====
 . Indicate estimate of percentage complete for the module		 ===== Synoptic Maps =====
 . SynopticMap : HMI synoptic maps are computed from the 720s line-of-sight magnetograms. Standard radial field synoptic charts are assembled by combining the 20 best observations made nearest central meridian at each longitude. It takes approximately 27.27 days to complete a solar rotation. Synoptic maps are provided in two resolutions and as line-of-sight and inferred radial field. The basic SynopticRadial chart is used to compute the other kinds. DailySynopticMaps insert data observed within 60 degrees of central meridian averaged over a 4-hour interval into the most recent synoptic chart.
 . A browsable catalog of MDI and [[http://hmi.stanford.edu/data/synoptic.html|HMI synoptic maps]].
Line 38: Line 31:
===== Status of Code =====
 . Name heritage or percent complete for Basic Code		 ===== HARPs - HMI Active Region Patches (HARPs) =====
 . [[HARPDataSeries]] : A HARP provides '''location information''' about a magnetic active region throughout its disk passage. Each 720s line-of-sight magnetogram is analyzed to generate a mask that indicates coherent regions of strong activity. The time series of masks is analyzed to identify persistent active regions. After the region rotates off the disk, a definitive time series is created that provides consistent geometric information about the HARP from before its first emergence to after its disappearance. HARPs are often associated with one or more NOAA active regions. For each numbered HARP at each time step a rectangular ''bitmap'' indicates which pixels on the CCD are part of the HARP and above a threshold.
Line 41: Line 34:
===== Status of DRMS module =====
 . Indicate status of DRMS module version of module		 ===== SHARPs - HMI Active Region Patches (HARPs) with Computed Space Weather Quantities =====
 . The SHARP data series collects maps of vector and scalar data products for each HARP region along with computed space-weather quantities. See the [[http://link.springer.com/article/10.1007/s11207-014-0529-3|SHARP]] paper for details.
Line 44: Line 37:
===== Issues needing resolution =====  . SpaceWeatherProducts - SHARPs - Active regions quantities computed from the vector magnetic field for each HARP time step are stored in SHARP keywords. The SHARP data series also provides links to cut-outs and remapped images of the HARPS. For more detail, see [[http://jsoc.stanford.edu/doc/data/hmi/sharp/sharp.htm|SHARP Explanation]].
 . The nrt SHARP data are available since 2012.09.14 at [[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_720s_nrt|hmi.sharp_720s_nrt]] or [[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_cea_720s_nrt|hmi.sharp_cea_720s_nrt]].
 . Source code is available for the [[http://jsoc.stanford.edu/cvs/JSOC/proj/sharp/apps|SHARP module]]
Line 46: Line 41:
  * List issues that still need to be resolved
  * Describe as many as you like		 === Links to Currently Available Magnetogram Data ===
 ||'''Magnetic Image Data''' ||||<style="text-align:center">Links to lookdata ||
 ||Line of sight Magnetograms ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.M_720s|hmi.M_720s]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.M_45s|hmi.M_45s]] ||
 ||Vector Magnetograms || [[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.B_720s|hmi.B_720s]] || ||
 ||Stokes Parameters ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.S_720s|hmi.S_720s]] || ||
 ||VFISV Inversion - ME ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.ME_720s_fd10|hmi.ME_720s_fd10]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.ME_720s_fd10_nrt|hmi.ME_720s_fd10_nrt]] ||
 ||Disambiguated Vector B SHARP ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_720s|hmi.sharp_720s]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_cea_720s|hmi.sharp_cea_720s]] ||
 ||NRT SHARP ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_720s_nrt|hmi.sharp_720s_nrt]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_cea_720s_nrt|hmi.sharp_cea_720s_nrt]] ||
 ||Old Disambiguated Vector B ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.B_720s_e15w1332_cutout|hmi.B_720s_e15w1332_cutout]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.B_720s_e15w1332_CEA|hmi.B_720s_e15w1332_CEA]] ||
 ||Obscure Data Products ||||<style="text-align:center">Summary Information about Some ObscureDataProducts ||
Line 49: Line 52:
===== Responsible scientist =====
 . Give name of local coordinator for development of this module
Line 52: Line 53:
===== Remarks =====
=== Links to Synoptic Maps ===
 HMI synoptic maps provide a composite view of the entire observable solar surface. They are computed from the 720s line-of-sight magnetic field measurements and come in 3600*1440 and 720*360 sizes.
 ||||||<style="text-align:center">Standard HMI Photospheric Field Carrington Synoptic Maps ||
 ||Line of sight synoptic map ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Synoptic_Ml_720s|hmi.Synoptic_Ml_720s]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Synoptic_Ml_720s_small|hmi.Synoptic_Ml_720s_small]] ||
 ||Assumed Radial component of LoS map ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Synoptic_Mr_720s|hmi.Synoptic_Mr_720s]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Synoptic_Mr_720s_small|hmi.Synoptic_Mr_720s_small]] ||
 ||||||<style="text-align:center">DailySynopticMaps ||
 ||Daily Update LoS Synoptic Map ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mldailysynframe_720s|hmi.Mldailysynframe_720s]] ||Soon: [[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mldailysynframe_720s_small|hmi.Mldailysynframe_720s_small]] ||
 ||Daily Update Radial Synoptic Map ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mrdailysynframe_720s|hmi.Mrdailysynframe_720s]] ||Soon: [[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mrdailysynframe_720s_small|hmi.Mrdailysynframe_720s_small]] ||
 ||||||<style="text-align:center">Daily NRT Synoptic Maps ||
 ||Daily Update NRT Los Synoptic Map ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mldailysynframe_720s_nrt|hmi.Mldailysynframe_720s_nrt]] ||Soon: [[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mldailysynframe_720s_nrt_small|hmi.Mldailysynframe_720s_nrt_small]] ||
 ||Daily Update NRT Radial Synoptic Map ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mrdailysynframe_720s_nrt|hmi.Mrdailysynframe_720s_nrt]] ||Soon: [[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mrdailysynframe_720s_nrt_small|hmi.Mrdailysynframe_720s_nrt_small]] ||



=== HMI Active Region Patches ===
A HARP (short for HMI Active Region Patch) is an enduring, coherent magnetic structure at the size scale of a solar active region. The primary purpose of the HARP data series is to provide the practical geometric information needed to follow an evolving region as it crosses the solar disk. A HARP is initially identified automatically in a sequence of HMI line-of-sight magnetograms. HARPs are typically observed over several days (possibly as long as a disk passage) and tracked from one image to the next. At each time step, the rectangular HARP bounding box is provided and a BITMAP that characterizes the pixels of the HARP is recorded. The bounding box encloses the maximum heliographic extent of the region during its life time. The BITMAP indicates which pixels in the box are part of the HMI active region patch and can be applied to an HMI image. Keywords provide summary information about the patch (e.g. the total line-of-sight magnetic flux) as well as geometric and heliographic specifics.

The HARP information is being used to determine regions of interest for vector field inversion processing, both for past data (hmi.ME_720s_fd10) and for near real time processing (hmi.ME_720s_fd10_nrt). Near real time HARPs (hmi.Mharp_720s_nrt) are a little different than definitive HARPs because the entire history or each region is not known; NRT and definitive HARP numbers differ.

See [[HARPDataSeries]] for details.

 ||HARP Data Series ||Definitive ||NRT ||
 ||[[http://sun.stanford.edu/~turmon/data/tracker-movies-notes/|Movie Description]] ||[[http://jsoc.stanford.edu/data/hmi/HARPs_movies/definitive|Monthly Movies]] ||[[http://jsoc.stanford.edu/data/hmi/HARPs_movies/nrt|Daily Movies]] ||
 ||Line of Sight ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mharp_720s|hmi.Mharp_720s]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.Mharp_720s_nrt|hmi.Mharp_720s_nrt]] ||
 ||Vector - ME ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.ME_720s_fd10|hmi.ME_720s_fd10]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.ME_720s_fd10_nrt|hmi.ME_720s_fd10_nrt]] ||
 ||SHARP - ccd ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_720s|hmi.sharp_720s]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_720s_nrt|hmi.sharp_720s_nrt]] ||
 ||SHARP - cea ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_cea_720s|hmi.sharp_cea_720s]] ||[[http://jsoc.stanford.edu/ajax/lookdata.html?ds=hmi.sharp_cea_720s_nrt|hmi.sharp_cea_720s_nrt]] ||
Line 57: Line 85:
 * Links to HMI PipelineCode
 * Back to Lev1Doc
 * Back to FrontPage
Line 58: Line 89:
    * Back to ["HMIModuleTable"]
    * Back to FrontPage		  * [[JsocContacts | Contacts]]

HMI Magnetic Field Products

http://jsoc.stanford.edu/data/hmi/images/latest/HMI_latest_Mag_256x256.gif

Four basic types of magnetic field products are described below.

Some data products suitable for space weather applications are available in near real time (nrt). Such data products always have nrt in the series name.

More details are provided at LineofsightMagneticField, VectorMagneticField, SynopticMaps, HARPDataSeries, SHARPs, and SpaceWeatherProducts.

Quick access to HMI magnetic field catalogs and data products can be found at http://hmi.stanford.edu/magnetic

Notes for users of HMI Magnetic field pipeline data can be found at PipelineCode

Available vector field papers for reference: Vector Field Pipeline Overview VFISV ME inversion SHARP

Line-of-sight Magnetograms

Vector Magnetic Field Image Data

  • VectorMagneticField : The vector magnetic field is computed from Stokes parameters derived from an independent set of polarized filtergrams. The basic vector field observing cadence is 135 seconds and uses images from HMI's Magnetic camera. The 36 filtergrams measure six polarization states, I plus or minus Q,U,and V, at six fixed wavelengths. All filtergrams are corrected for instrumental effects and interpolated to the proper time. Most analysis is done with weighted averages computed every 720s using data collected over 1215 seconds (nine 135s intervals). The processing happens in three steps. First Stokes parameters (hmi.S_720s) are computed from level 1 filtergrams. Then a Milne-Eddington inversion is performed to determine the field and other plasma parameters (hmi.ME_720s_fd10). Finally disambiguation is performed to determine the field azimuth angle See Vector Field Pipeline Overview for a description.

  • FullDiskDisamb : Full-disk disambiguated vector magnetic field images are available every 12 minutes starting on 19 December 2013 and can be found at hmi.B_720s. Magnetograms for earlier times can be computed upon request. These full disk disambiguation results are used to produce SHARPs starting on Jan 15, 2014.

  • Vector Field in HMI Active Region Patches : (hmi.sharp_720s, hmi.sharp_cea_720s )

Synoptic Maps

  • SynopticMap : HMI synoptic maps are computed from the 720s line-of-sight magnetograms. Standard radial field synoptic charts are assembled by combining the 20 best observations made nearest central meridian at each longitude. It takes approximately 27.27 days to complete a solar rotation. Synoptic maps are provided in two resolutions and as line-of-sight and inferred radial field. The basic SynopticRadial chart is used to compute the other kinds. DailySynopticMaps insert data observed within 60 degrees of central meridian averaged over a 4-hour interval into the most recent synoptic chart.

  • A browsable catalog of MDI and HMI synoptic maps.

HARPs - HMI Active Region Patches (HARPs)

  • HARPDataSeries : A HARP provides location information about a magnetic active region throughout its disk passage. Each 720s line-of-sight magnetogram is analyzed to generate a mask that indicates coherent regions of strong activity. The time series of masks is analyzed to identify persistent active regions. After the region rotates off the disk, a definitive time series is created that provides consistent geometric information about the HARP from before its first emergence to after its disappearance. HARPs are often associated with one or more NOAA active regions. For each numbered HARP at each time step a rectangular bitmap indicates which pixels on the CCD are part of the HARP and above a threshold.

SHARPs - HMI Active Region Patches (HARPs) with Computed Space Weather Quantities

  • The SHARP data series collects maps of vector and scalar data products for each HARP region along with computed space-weather quantities. See the SHARP paper for details.

  • SpaceWeatherProducts - SHARPs - Active regions quantities computed from the vector magnetic field for each HARP time step are stored in SHARP keywords. The SHARP data series also provides links to cut-outs and remapped images of the HARPS. For more detail, see SHARP Explanation.

  • The nrt SHARP data are available since 2012.09.14 at hmi.sharp_720s_nrt or hmi.sharp_cea_720s_nrt.

  • Source code is available for the SHARP module

HMI Active Region Patches

A HARP (short for HMI Active Region Patch) is an enduring, coherent magnetic structure at the size scale of a solar active region. The primary purpose of the HARP data series is to provide the practical geometric information needed to follow an evolving region as it crosses the solar disk. A HARP is initially identified automatically in a sequence of HMI line-of-sight magnetograms. HARPs are typically observed over several days (possibly as long as a disk passage) and tracked from one image to the next. At each time step, the rectangular HARP bounding box is provided and a BITMAP that characterizes the pixels of the HARP is recorded. The bounding box encloses the maximum heliographic extent of the region during its life time. The BITMAP indicates which pixels in the box are part of the HMI active region patch and can be applied to an HMI image. Keywords provide summary information about the patch (e.g. the total line-of-sight magnetic flux) as well as geometric and heliographic specifics.

The HARP information is being used to determine regions of interest for vector field inversion processing, both for past data (hmi.ME_720s_fd10) and for near real time processing (hmi.ME_720s_fd10_nrt). Near real time HARPs (hmi.Mharp_720s_nrt) are a little different than definitive HARPs because the entire history or each region is not known; NRT and definitive HARP numbers differ.

See HARPDataSeries for details.

JsocWiki: MagneticField (last edited 2014-11-18 05:17:51 by ToddHoeksema)