Physics of the solar atmosphere
In 2014 the Department of Astronomy at Stockholm University has started a theoretical/computational solar physics group. Currently it consists of an associate professor, 6 postdocs/researchers and 3 PhD students. The aim of the group is to understand the physics of the atmosphere of the Sun. Group member J. de la Cruz Rodriguez got a VR Young Researcher grant starting 2016. His project "What is heating the magnetic solar chromosphere" will make intensive usage of the Nicole and SPARSE inversion codes using SNIC resources. In Oct 2016, PI Leenaarts was awarded a large grant from the Knut and Alice Wallenberg foundation for the project "Fundamental magnetic processes in the solar chromosphere", which involves a substantial amount of numerical modelling. Magnetism underlies much of the activity and dynamics of the solar atmosphere. Observations with observatories such as SDO, IRIS and the Swedish Solar Telescope show an intricate structure and dynamics form the smalls observable scale to the size of the entire Sun. These phenomena are ultimately driven by the nuclear fusion in the solar centre and the enigmatic solar dynamo. The physics of the atmosphere is complex, encompassing the interaction of (polarised) radiation and matter, magneto-hydrodynamics and plasma physics. Understanding the observations in terms of the physics thus requires intricate theoretic modelling. The project "Physics of the solar atmosphere" aims to contribute to our understanding of the solar atmosphere through (1) radiation-MHD modelling of the atmosphere, (2) precise modelling of the spectral lines from these MHD models that can be directly compared to observations and (3) inversion of observations. Inversion is an iterative technique where an atmospheric structure is derived that is consistent the observed spectral line profiles. The group uses a variety of codes for which the PI and Co-I are co-developers. All codes have been run before on both SNIC and non-SNIC supercomputers. We are performing regular production runs on SNIC resources and have published 5 refereed papers using SNIC resources in 2016/2017. We expect to submit 10 papers to refereed journals during 2017. We ask for 400,000 hours per month on Beskow and 400,000 hours per month on Kebnekaise.