Abstract
Abstract. We converted the radiation part of the atmospheric model ECHAM to a single-precision arithmetic. We analyzed different conversion strategies and finally used a step-by-step change in all modules, subroutines and functions. We found out that a small code portion still requires higher-precision arithmetic. We generated code that can be easily changed from double to single precision and vice versa, basically using a simple switch in one module. We compared the output of the single-precision version in the coarse resolution with observational data and with the original double-precision code. The results of both versions are comparable. We extensively tested different parallelization options with respect to the possible runtime reduction, at both coarse and low resolution. The single-precision radiation itself was accelerated by about 40 %, whereas the runtime reduction for the whole ECHAM model using the converted radiation achieved 18 % in the best configuration. We further measured the energy consumption, which could also be reduced.
Highlights
The atmospheric model ECHAM was developed at the Max Planck Institute for Meteorology (MPI-M) in Hamburg
The model is used in different Earth system models (ESMs) as an atmospheric component, e.g., in the MPI-ESM developed at the MPIM; see Fig. 1
In the PalMod project, two different strategies to improve the performance of the radiation part are investigated: one is to run the radiation in parallel on different processors; the other one is the conversion to single-precision arithmetic we present in this paper
Summary
The atmospheric model ECHAM was developed at the Max Planck Institute for Meteorology (MPI-M) in Hamburg. Its development started in 1987 as a branch of a global weather forecast model of the European Centre for Medium-Range Weather Forecasts (ECMWF), leading to the acronym (EC for ECMWF, HAM for Hamburg). The model is used in different Earth system models (ESMs) as an atmospheric component, e.g., in the MPI-ESM developed at the MPIM; see Fig. 1. For a detailed list on ECHAM publications we refer to the home page of the institute Version 5 of the model was used in the 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2007) and version 6 in the Coupled Model Intercomparison Project CMIP (World Climate Research Programme, 2019a)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
