The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance (English)

In: Solar Physics   ;  289 ,  9  ;  3483-3530  ;  2014

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Abstract The Helioseismic and Magnetic Imager (HMI) began near-continuous full-disk solar measurements on 1 May 2010 from the Solar Dynamics Observatory (SDO). An automated processing pipeline keeps pace with observations to produce observable quantities, including the photospheric vector magnetic field, from sequences of filtergrams. The basic vector-field frame list cadence is 135 seconds, but to reduce noise the filtergrams are combined to derive data products every 720 seconds. The primary 720 s observables were released in mid-2010, including Stokes polarization parameters measured at six wavelengths, as well as intensity, Doppler velocity, and the line-of-sight magnetic field. More advanced products, including the full vector magnetic field, are now available. Automatically identified HMI Active Region Patches (HARPs) track the location and shape of magnetic regions throughout their lifetime. The vector field is computed using the Very Fast Inversion of the Stokes Vector (VFISV) code optimized for the HMI pipeline; the remaining 180∘ azimuth ambiguity is resolved with the Minimum Energy (ME0) code. The Milne–Eddington inversion is performed on all full-disk HMI observations. The disambiguation, until recently run only on HARP regions, is now implemented for the full disk. Vector and scalar quantities in the patches are used to derive active region indices potentially useful for forecasting; the data maps and indices are collected in the SHARP data series, hmi.sharp_720s. Definitive SHARP processing is completed only after the region rotates off the visible disk; quick-look products are produced in near real time. Patches are provided in both CCD and heliographic coordinates. HMI provides continuous coverage of the vector field, but has modest spatial, spectral, and temporal resolution. Coupled with limitations of the analysis and interpretation techniques, effects of the orbital velocity, and instrument performance, the resulting measurements have a certain dynamic range and sensitivity and are subject to systematic errors and uncertainties that are characterized in this report.

Table of contents – Volume 289, Issue 9

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3231
Preface
Guhathakurta, Madhulika | 2014
3233
Advances in Observing Various Coronal EUV Waves in the SDO Era and Their Seismological Applications (Invited Review)
Liu, Wei / Ofman, Leon | 2014
3279
CorPITA: An Automated Algorithm for the Identification and Analysis of Coronal “EIT Waves”
Long, D. M. / Bloomfield, D. S. / Gallagher, P. T. / Pérez-Suárez, D. | 2014
3297
A New Sigmoid Catalog from Hinode and the Solar Dynamics Observatory: Statistical Properties and Evolutionary Histories
Savcheva, A. S. / McKillop, S. C. / McCauley, P. I. / Hanson, E. M. / DeLuca, E. E. | 2014
3313
Solar Dynamics Observatory and Hinode Observations of a Blowout Jet in a Coronal Hole
Young, P. R. / Muglach, K. | 2014
3331
Quiescent Reconnection Rate Between Emerging Active Regions and Preexisting Field, with Associated Heating: NOAA AR 11112
Tarr, Lucas A. / Longcope, Dana W. / McKenzie, David E. / Yoshimura, Keiji | 2014
3351
Formation of a Flare-Productive Active Region: Observation and Numerical Simulation of NOAA AR 11158
Toriumi, S. / Iida, Y. / Kusano, K. / Bamba, Y. / Imada, S. | 2014
3371
Synoptic Solar Cycle 24 in Corona, Chromosphere, and Photosphere Seen by the Solar Dynamics Observatory
Benevolenskaya, E. / Slater, G. / Lemen, J. | 2014
3381
Using Polar Coronal Hole Area Measurements to Determine the Solar Polar Magnetic Field Reversal in Solar Cycle 24
Karna, N. / Hess Webber, S. A. / Pesnell, W. D. | 2014
3391
Extreme Ultraviolet Late-Phase Flares: Before and During the Solar Dynamics Observatory Mission
Woods, Thomas N. | 2014
3403
The Quest to Understand Supergranulation and Large-Scale Convection in the Sun
Hanasoge, Shravan M. / Sreenivasan, Katepalli R. | 2014
3421
Additional Evidence Supporting a Model of Shallow, High-Speed Supergranulation
Duvall, T. L. Jr. / Hanasoge, S. M. / Chakraborty, S. | 2014
3435
Solar-Cycle Variation of Subsurface Zonal Flow
Komm, R. / Howe, R. / González Hernández, I. / Hill, F. | 2014
3457
Interpreting the Helioseismic and Magnetic Imager (HMI) Multi-Height Velocity Measurements
Nagashima, Kaori / Löptien, Björn / Gizon, Laurent / Birch, Aaron C. / Cameron, Robert / Couvidat, Sebastien / Danilovic, Sanja / Fleck, Bernhard / Stein, Robert | 2014
3483
The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
Hoeksema, J. Todd / Liu, Yang / Hayashi, Keiji / Sun, Xudong / Schou, Jesper / Couvidat, Sebastien / Norton, Aimee / Bobra, Monica / Centeno, Rebecca / Leka, K. D. et al. | 2014
3531
The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Optimization of the Spectral Line Inversion Code
Centeno, R. / Schou, J. / Hayashi, K. / Norton, A. / Hoeksema, J. T. / Liu, Y. / Leka, K. D. / Barnes, G. | 2014
3549
The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: SHARPs – Space-Weather HMI Active Region Patches
Bobra, M. G. / Sun, X. / Hoeksema, J. T. / Turmon, M. / Liu, Y. / Hayashi, K. / Barnes, G. / Leka, K. D. | 2014