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license: apache-2.0
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# ACE2-ERA5

Ai2 Climate Emulator (ACE) is a family of models designed to simulate atmospheric variability from the time scale of days to centuries.

**Disclaimer: ACE models are research tools and should not be used for operational climate predictions.**

ACE2-ERA5 is trained on the [ERA5 dataset](https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.3803) and will be described in a forthcoming paper.

Code for doing inference with ACE models can be found here: [https://github.com/ai2cm/ace](https://github.com/ai2cm/ace)
with corresponding documentation here: [https://ai2-climate-emulator.readthedocs.io/en/stable/](https://ai2-climate-emulator.readthedocs.io/en/stable/)

Briefly, the strengths of ACE2-ERA5 are:
- accurate atmospheric warming response to combined increase of sea surface temperature and CO2 over last 80 years
- highly accurate atmospheric response to El Niño sea surface temperature variability
- good representation of geographic distribution of tropical cyclones
- accurate Madden Julian Oscillation variability
- realistic stratospheric polar vortex strength and variability
- exact conservation of global dry air mass and moisture

Some known weaknesses are:
- the individual sensitivities to increased sea surface temperature and CO2 are not entirely realistic
- the medium-range (3-10 day) weather forecast skill is not state of the art
- not expected to generalize accurately for large perturbations of inputs (e.g. doubling of CO2)