Title:	Physics of the solar atmosphere
DNr:	SNIC 2016/1-131
Project Type:	SNIC Medium Compute
Principal Investigator:	Jorrit Leenaarts <jorrit.leenaarts@astro.su.se>
Affiliation:	Stockholms universitet
Duration:	2016-04-01 – 2017-01-01
Classification:	10305
Keywords:

Abstract

IN 2014 the Department of Astronomy at Stockholm University has started a theoretical/computational solar physics group. Currently it consists of an associated professor, 4 postdocs/researchers and a PhD student. 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. 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. An earlier project (implementing partial frequency redistribution in the Multi3d code) is now finished. We have used SNIC 2015/1--122 resources for development and testing, and we are writing the first paper about this method. We expect our usage of this computationally intensive method to increase significantly, so we need more computing time than last year. Another project that has been ongoing using SNIC 2015/1--122 resources (multi-grid methods) is now in it's final testing stages. We will need more CPU time for finishing this project and starting production runs using it. Finally we have written a new code (SPARSE, see code description part below) that is now ready to be tested and ported to SNIC resources. Therefore we ask for 200,000 hours per month on Beskow and 40,000 hours per month on Triolith.