The fact that the CLASP observations cannot be reproduced by today’s models of the solar atmosphere suggests that the 3D structure of the chromosphere-corona transition region is much more complex than previously thought.  In order to confirm this idea, the scientific team has carried out a complex theoretical investigation in order to determine the magnetization and geometrical complexity of the transition region that best explains the experimental data.

With the help of the MareNostrum supercomputer of the National Supercomputing Center in Barcelona, the researchers have calculated what would be the expected polarization signals for a large number of 3D atmospheric models, constructed by changing the degree of magnetization and geometrical complexity of the 3D solar model atmosphere illustrated in Figure 1.

Such study has led to two important conclusions, namely, the transition region of the atmospheric model that  most likely explains the CLASP observations has a significantly larger degree of geometrical complexity and a smaller degree of magnetization. The results of this investigation make it evident the need to develop more realistic 3D models of the solar atmosphere, by including phenomena such as spicules, ubiquitous in high-resolution observations of the line-core intensity in strong chromospheric lines, but not present in today’s 3D models of the solar atmosphere.