Data compression for local correlation tracking of solar granulation

B. Loptien, A. C. Birch, T. L. Duvall, L. Gizon, J. Schou

Research output: Contribution to journalArticle

Abstract

Several upcoming and proposed space missions, such as Solar Orbiter, will be limited in telemetry and thus require data compression. Aims. We test the impact of data compression on local correlation tracking (LCT) of time series of continuum intensity images. We evaluate the effect of several lossy compression methods (quantization, JPEG compression, and a reduced number of continuum images) on measurements of solar differential rotation with LCT. Methods. We applied the different compression methods to tracked and remapped continuum intensity maps obtained by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. We derived 2D vector velocities using the local correlation tracking code Fourier Local Correlation Tracking (FLCT) and determined the additional bias and noise introduced by compression to differential rotation. Results. We find that probing differential rotation with LCT is very robust to lossy data compression when using quantization. Our results are severely affected by systematic errors of the LCT method and the HMI instrument. The sensitivity of LCT to systematic errors is a concern for Solar Orbiter.

Original languageEnglish (US)
Article numberA9
JournalAstronomy and Astrophysics
Volume587
DOIs
StatePublished - Mar 1 2016

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Keywords

  • Methods: data analysis
  • Sun: helioseismology

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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