Authors: Xiaoyan Xie (Harvard-Smithsonian Center for Astrophysics), Gang Li (University of Alabama in Huntsville), Katharine Reeves (Harvard-Smithsonian Center for Astrophysics)

 We develop various procedures to examine the turbulence characteristics in the solar corona, during both quiet periods and during eruptions. Our study focuses on the intensities of various EUV line emissions. Unlike in-situ solar wind, where the turbulence is considered stationary, and homogeneous, emission lines during solar flares are neither stationary nor homogeneous. This severely affects the often-adopted power analysis, which recently has been used in examining current sheet turbulence.

 However, we found that the method of structure function, with adaptation, is unexpectedly useful for our study purpose. Our main findings so far are: 1) there is a clear signature of MHD turbulence in EUV observations revealed through examining structure functions for both intensity and density, both prior to eruption and during eruption. 2) signatures of turbulence emerge in both the frequency domain, when we examine the intensity at a single location for a period of time, and in the wavenumber domain, when we examine the intensity along a spatial cut; 3) when an eruption occurs, the power spectrum of turbulence, which is related to the second order structure function, differs from the background value; 4)  one has to be careful when examining the turbulence since the situation is not homogeneous, nor stationary; 5) complementary wavelet analysis can be useful and needs to be included to examine the strength of the turbulence.

This preliminary study opens a new window to explore turbulence features from massive SDO/AIA observations with various structures.   Combining this study with other remote sensing observations, in particular the non-thermal velocity maps from, e.g. COMP and DKIST, will be pursued in the future.