May 5, 2017, 1:00 pm - 2:00 pm

May 5, 1:00 pm - 2:00 pm

Tracking the not-so-quiet Sun in the SDO era

Raphael Attie (GSFC/671)

Measurements of solar photospheric flows by algorithms applied to image series are part of a larger effort to automatically extract solar properties using advanced image processing methods. Because solar plasma flows exist at several scales, some of which are not immediately apparent on solar image series, sophisticated and automated tracking procedures are needed. I will present here new tracking techniques to analyze the horizontal plasma flows that use the 'Balltracking' paradigm. It has evolved in two different branches for achieving complementary objectives:

(i) Originally developed to track granules in MDI images - I adapted the Balltracking paradigm to efficiently track full-cadence data series from SDO/HMI and to characterize the flows during the emergence of active regions (ARs). This method only derives flow fields where granules are observed, in the Euler reference frame.

(ii) I also developed the so-called 'Magnetic Balltracking' algorithm that tracks magnetic elements in the Lagrange reference frame in quiet Sun magnetograms (Attie & Innes 2015, Attie et al. 2016) and I will discuss its capacity to track magnetic flux in ARs, from their early emergence until their late decay.

Used together on SDO/HMI data, 'Balltracking' and 'Magnetic Balltracking' provide a solar tracking framework that will help to address the following questions: (i) What are the properties of large-scale photospheric flows prior to and after the emergence of ARs? (ii) To what extent does the photospheric flows convert kinetic energy into magnetic stress and what are their contribution to the magnetic free energy transfer into and out of the corona? (iii) How do the solar photospheric flows and magnetic field vary and interact over large areas and long timescales? (iv) For space weather predictions,