The Low-Resolution Version of HadGEM3 GC3.1: Development and Evaluation for Global Climate

Area of Science:

• Climate modeling
• Earth System Science
• Oceanography

Background:

• Existing climate models require significant computational resources.
• Advancements in model resolution impact climate simulation accuracy and performance.
• HadGEM3 N96ORCA1 is a new configuration of the established HadGEM3 model.

Purpose of the Study:

• Introduce and evaluate the HadGEM3 N96ORCA1 climate model.
• Compare its performance against observations and a higher-resolution model (N216ORCA025).
• Assess its suitability for future climate research, including CMIP6.

Main Methods:

• Developed HadGEM3 N96ORCA1 with ~135 km atmospheric and 1° ocean horizontal resolution.
• Compared model outputs for climate mean, variability, and biases against observational data.
• Evaluated key climate phenomena such as Atlantic meridional overturning circulation, ENSO, and AMV.

Main Results:

• HadGEM3 N96ORCA1 demonstrates comparable scientific performance to N216ORCA025 with significantly reduced computational cost.
• The model accurately reproduces observed climate means and variability, with similar bias patterns to N216ORCA025.
• Specific biases, like the cold surface bias in the North Atlantic and a reduced warm bias in the Southern Ocean, were noted and analyzed.
• Simulated ocean circulation, ENSO, and AMV align well with observational data.

Conclusions:

• HadGEM3 N96ORCA1 provides a computationally efficient yet scientifically robust climate modeling tool.
• The model's performance makes it a valuable component for the UK Earth System Model (UKESM1) and CMIP6.
• Further research can leverage this model for extensive climate change projections and analyses.