NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Achieving Consistent Doppler Measurements from SDO/HMI Vector Field InversionsNASA's Solar Dynamics Observatory is delivering vector magnetic field observations of the full solar disk with unprecedented temporal and spatial resolution; however, the satellite is in a highly inclined geosynchronous orbit. The relative spacecraft-Sun velocity varies by +/-3 kms−1 over a day, which introduces major orbital artifacts in the Helioseismic Magnetic Imager (HMI) data. We demonstrate that the orbital artifacts contaminate all spatial and temporal scales in the data. We describe a newly developed three-stage procedure for mitigating these artifacts in the Doppler data obtained from the Milne-Eddington inversions in the HMI pipeline. The procedure ultimately uses 32 velocity-dependent coefficients to adjust 10 million pixels-a remarkably sparse correction model given the complexity of the orbital artifacts. This procedure was applied to full-disk images of AR 11084 to produce consistent Dopplergrams. The data adjustments reduce the power in the orbital artifacts by 31 dB. Furthermore, we analyze in detail the corrected images and show that our procedure greatly improves the temporal and spectral properties of the data without adding any new artifacts. We conclude that this new procedure makes a dramatic improvement in the consistency of the HMI data and in its usefulness for precision scientific studies.
Document ID
20170002658
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Schuck, Peter W.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Antiochos, S. K.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Leka, K. D.
(Northwest Research Associates, Inc. Boulder, CO, United States)
Barnes, Graham
(Northwest Research Associates, Inc. Boulder, CO, United States)
Date Acquired
March 29, 2017
Publication Date
May 26, 2016
Publication Information
Publication: The Astrophysical Journal
Publisher: AGU
Volume: 823
Issue: 2
ISSN: 0004-637X
e-ISSN: 1538-4357
Subject Category
Solar Physics
Report/Patent Number
GSFC-E-DAA-TN40701
Funding Number(s)
CONTRACT_GRANT: NNH12CC03C
CONTRACT_GRANT: NNH12CG10C
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available