On Determination of the Solar Atmosphere Parameters above Active Regions by Radio Observations
Alexey Stupishin, St. Petersburg State University
We introduced new algorithm of atmosphere parameters (temperature height profile and electron density) determination above the active regions, based on the algorithm developed in our previous work . In the method presented now we attribute the initial temperature to each height layer and scrupulously consider the contribution of each height layer at every observing radio map point in some frequency range. Such investigation allow us to correct temperatures. After the temperature profile correcting the algorithm applied iteratively until convergence.
Using this algorithm for the dipole model of magnetic field, model of temperature height profile and simulated RATAN-600 radio telescope scans shows that we get very good correspondence between modeled and calculated temperature profiles (< 0.2%).
Application of the method to the observation of the real active regions on RATAN-600 shows that we can get realistic temperatures in the lower corona (2-3 MK) and the height of transition region (about 1 Mm).
Until this we suppose that the temperature above the whole active region is the same at each height. But semi-empirical models of solar atmosphere shows that the temperature height profiles are different above different regions of sunspots (such as umbra and penumbra). This, particularly, can explain wide transition regions which we get in calculations. We suggested ways of adaptation of the suggested method to more complex models of atmosphere and to the radio observations on telescopes provide 2-D radio maps.
 A. G. Stupishin, T. I. Kaltman, V. M. Bogod, and L. V. Yasnov. Modeling of Solar Atmosphere Parameters
Above Sunspots Using RATAN-600 Microwave Observations. Solar Phys., 293:13, January 2018.