HighResMIP versions of EC-Earth: EC-Earth3P and EC-Earth3P-HR – description, model computational performance and basic validation

Abstract. A new global high-resolution coupled climate model, EC-Earth3P-HR

has been developed by the EC-Earth consortium, with a resolution of

approximately 40 km for the atmosphere and 0.25 ∘ for the ocean,

alongside with a standard-resolution version of the model, EC-Earth3P (80 km

atmosphere, 1.0 ∘ ocean). The model forcing and simulations follow the

High Resolution Model Intercomparison Project (HighResMIP) protocol. According to this protocol, all simulations are made

with both high and standard resolutions. The model has been optimized with

respect to scalability, performance, data storage and post-processing. In

accordance with the HighResMIP protocol, no specific tuning for the high-resolution version has been applied. Increasing horizontal resolution does not result in a general reduction of

biases and overall improvement of the variability, and deteriorating impacts

can be detected for specific regions and phenomena such as some

Euro-Atlantic weather regimes, whereas others such as the El Nino–Southern

Oscillation show a clear improvement in their spatial structure. The

omission of specific tuning might be responsible for this. The shortness of the spin-up, as prescribed by the HighResMIP protocol,

prevented the model from reaching equilibrium. The trend in the control and

historical simulations, however, appeared to be similar, resulting in a

warming trend, obtained by subtracting the control from the historical

simulation, close to the observational one.