The infrastructure MESSy submodels GRID (v1.0) and IMPORT (v1.0)

Abstract. The coupling of Earth system model components, which work on different grids, into an Earth System Model (ESM) provokes the necessity to transfer data from one grid to another. Additionally, each of these model components might require data import onto its specific grid. Usually, one of two approaches is used: Either all input data is preprocessed to the employed grid, or the imported data is interpolated on-line, i.e. during model integration to the required grid. For the former, each change in the model resolution requires the re-preprocessing of all data. The latter option implies that in each model integration computing time is required for the grid mapping. If all components of an ESM use only one single point of import and the same mapping software, only one software package needs to be changed for code optimisation, inclusion of additional interpolation methods or the implementation of new data formats.

As the Modular Earth Submodel System (MESSy) is mainly used for research purposes which require frequent changes of the model setup including the model resolution or the application of different sets of input data (e.g., different emission scenarios), the idea of a common procedure for data import was implemented in MESSy in form of the infrastructure submodel IMPORT. Currently, IMPORT consists of two submodels: IMPORT_TS for reading and processing abstract time series data and IMPORT_GRID, utilising the infrastructure submodel GRID which provides procedures for grid transformations using the remapping software packages NREGRID (Jöckel, 2006) and SCRIP (Jones, 1999). Grid information is stored in a standardised structure as geo-hybrid grids. Based on this unified definition a standardised interface for the grid transformations is provided, thus simplifying the implemention of grid transformations in the model code.

This article describes the main functionalities of the two MESSy infrastructure submodels GRID and IMPORT. The Supplement of this article contains stand-alone tools of both IMPORT subsubmodels, IMPORT_TS and IMPORT_GRID. Their handling is explained in detail in the IMPORT User Manual which is also part of the Supplement.