MECCA-based (full) Chemistry

- work in progress -

In this configuration example a simulation with (full) MECCA-based chemistry is performed. If we talk about MECCA-based chemistry we mean a full gas phase chemistry that can be applied additionally to the existing standard parametrized chemistry from ICON-ART (explained in the article Atmospheric Chemistry, example: click here). MECCA uses the Kinetic PreProcessor (KPP) to convert the chemical equations into differential equations that can be used then e.g., in ICON-ART. MECCA already contains a comprehensive chemical mech- anism, but it also allows to create an own mechanism by changing equations or only picking a subset of equations. To perform this example, a complete reaction mechanism is created and transferred to ICON-ART.

This article teaches you...

• the implementation of (full) MECCA-based chemistry in ICON-ART
• the creation of a chemical mechanism and the selection of the respective desired chemical species and their reactions in MECCA
• the implementation of not yet in MECCA implemented reactions in your mechanism
• the creation of the to your mechanism belonging Mecca-xml data to link MECCA calculations with ICON-ART

Introductioin

The MECCA(=Module Efficiently Calculating the Chemistry of the Atmosphere) based chemistry describes a full gas phase chemistry that can be applied as an extension to the parametrized Simplified Chemistry (see above). MECCA based chemistry is generally more exact in the concentration values but the overall runtime is longer compared to purely simplified chemistry simulations. MECCA itself is originally a submodule of the CAABA box model where an air parcel is described as a box and outgoing from this model all exchange processes in- and outward of the box are calculated. As MECCA is part of this model, it contains a wide collection of the most important reactions, including Ozone-, Methane-, HOx-, NOx-, Carbonhydrogen-, Halogene- and Sulfur chemistry. MECCA is available in a supplement, available to download for free and containing all auxiliaries to perform MECCA-simulations.

In this case we are going to have a look at the implementation of the fully available chemistry, meaning all in default mode available reactions will be implemented. This could also be adjusted easily if necessary and will be showed later. If we talk about "adding" MECCA chemistry to ICON-ART, it means that it is additionally calculated to the in any way calculated parametrized simplified chemistry in ICON-ART.

(Note: Adding MECCA-chemistry to ICON-ART also means that some namelist parameters will be overwritten in the runscript which means that some extra options (e.g. LINOZ-chemistry) are only available by setting them manually in the ICON-ART code.)

In this configuration case a regular simulation with a MECCA chemistry implementation that will be applied in most cases is explained. To get an overview about the upcoming steps you can also check out the MECCA chemistry part in the Atmospheric Chemistry article.