Troposphere (IEK-8)

The group is mostly involved in studies on reactive intermediates such as radicals and carbonyl oxides (alkoxy radicals, alkylperoxy radicals, Criegee intermediates). These species have access to a very diverse set of chemical reactions, allowing these species to break apart, re-arrange to a different species, or react with other molecules present in the atmosphere to combine to larger molecules, or create new molecular fragments. The competition between all these processes determines the atmospheric fate of any given compound, i.e. whether it will fall apart to small gaseous molecules, or instead form larger molecules that form particles, affect air quality and health, or have an influence on our climate.

Three approaches are used by our group. The first is to examine important reactions in high detail, to determine how the reaction works, how fast it goes as a function of the reaction conditions (.e.g temperature and pressure), and which products come out of it. This information is highly valuable to understand how the chemistry in the atmosphere proceeds. Secondly, we examine large chemical kinetic models of key organic material emitted to the atmosphere, and determine how it degrades step by step, in a complex network of hundreds of reactions, interacting with other species in the atmosphere. Finally, we examine systematic variations of molecules, all undergoing the same type of reaction. From these studies, we can derive so-called “structure-activity relationships” (SARs) which can predict the chemical activity of a new molecule, based solely on its structure. This information is needed for modeling studies, which attempt to explicitly describe the chemistry of many thousands of molecules in the atmosphere.

The theoretical kinetics group runs a modest computational cluster, designed specifically for the type of calculations needed for our research. Some characteristics:

• Intel Xeon-based CPUs with up to 28 cores per node (dual cpu); 230 cores total
• Up to 128GB of memory per node; 1.5TB total
• Up to 5TB of high-speed DAS disk scratch space per node; 57TB total disk RAID
• Torque resource manager + Maui queuing system
• Quantum chemical and theoretical kinetic applications installed

The cluster is physically hosted at the JSC (Jülich Supercomputing Center).