On-line Diagnostics in Climate Simulations - Status and Perspectives

Kurzfassung

On-line diagnostics are calculations performed during the simulation of a numerical model. The applications of these tools range from simple calculations for consistency checks during a simulation, over more advanced calculations of results which could be used straight from the model output, to special diagnostics which can only be calculated on-line as they make use of the high temporal or spatial resolution of the model. In recent years increasing computational power of high-performance computers is accompanied by a large amount of calculated data. The I/O bandwidth, however, did not increase accordingly and became a serious bottleneck in model performance. On-line diagnostics could help to mitigate this problem by reducing the amount of data written out. Even more, as model output does not have to be read in again to perform additional diagnostic post-processing. In this presentation, we focus on the chemistry-climate model EMAC (ECHAM-MESSy Atmospheric Chemistry model) and the techniques to include (couple) diagnostic tools into the model system. Several diagnostic tools and their applications are presented as examples. We explore the design and principles of the interface used in EMAC (the Modular Earth Submodel System; MESSy) in some detail. Furthermore, we present a current project to include user defined diagnostic tools into simulations (of several numerical models) in a flexible manner.