Developing ACCESS-ESM1.5 for the past warm world of the Miocene


Developing ACCESS-ESM1.5 for the past warm world of the Miocene


Dave Hutchinson (@dkhutch), UNSW



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We did similar things with the ACCESS-N48 coupled model: Drake Passage closed, new continents, remove Australia … many work others still crash …

… and yes it is a real pain to get this going, but it really should be much simpler.

best regards

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Great talk, thanks @dkhutch.

You said at the beginning of your talk that paleo climates have some relevance for projected increased greenhouse gas scenarios in our future. How much do the large changes in ocean circulation, particularly Antarctic isolation affect the utility of paleo climates as proxies for our near future climate?

Thanks for your talk, Dave. I have been spending some time tracking down people who have been using the UM for paleoclimate simulations.
Kenji Izumi has been doing Last Glacial Maximum simulations. As I understand it, these involve changing the extent of land ice, but not the location of conntinents.
See (e.g.) for previous Rose/Cylc suites, and ORCID for publications.

I have also seen some paleo simulations in rose-stem tests. Details to follow.

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I have just looked through current UM sources and can’t find any paleoclimate tests in rose-stem. So it looks like I was wrong there. Sorry.

See also for a list of BRIDGE paleoclimate simulations that use the UM. You may want to contact Paul Valdes to find out how BRIDGE creates UM-based paleoclimate simulations. Many of these simulations look to be quite old - some look like they use UMUI rather than Rose/Cylc for example.

Charlie Williams, Alistair Sellar and Sebastian Steinig have been running Eocene simiulations with matching ancillary files. See

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Thanks Dietmar, it really helps to have community interested in these kinds of experiments, so it’s great to be able to compare notes with your N48 simulations.

Hi Aidan,
One way to make these examples more applicable to future climate is to derive climate sensitivity for the particular configuration. In the DeepMIP example, 55 million years ago, we estimate a “non-CO2” component of global warming to be 4.5 degC. The non-CO2 component comes from all the boundary condition changes, including paleogeography and removing all the ice. So, in the Eocene model ensemble, with 280 ppm CO2(pre-industrial), we already get about 4.5 deg C of warming.

Climate sensitivity (w.r.t. to pre-industrial) due to CO2 is then calculated with an offset of -4.5 degC, to take that into account.

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Hi Paul,
Thanks for this. That is super cool that you have tracked down the ancillary files used by the Bristol team. I have just recently gained access to the Met Office MOSRS system, so I will definitely look into those.

@HIMADRI_SAINI Please see this topic for previous paleoclimate simulations that used UM.

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See also

Right now, some of the ancillary files used by the Bristol team are sitting on a /home directory somewhere other than at NCI.
For example, see u-cn502:

[pcl851@gadi-login-06 u-cn502]$ find . -type f | grep -v '/pristine/' | sort | xargs grep '/home/' | grep ancil

@MartinDix See this topic for responses to “Developing ACCESS-ESM1.5 for the past warm world of the Miocene”. Researchers at Bristol have been using the UM for Paleoclimate simulations, but details of their ancillary file configuration are not immediately available at NCI. Perhaps one of us should contact them to see if NCI can mirror their files, see what scripts they used to generate them, etc.

Dear Paul,
I do not think this will help us much. @abhik has tried this, but we are dealing with a different coupled model with the ocean being MOM. We have not problems with MOM and also not with the UM. The problem that we have is the coupled ACCESS model.

@MartinDix @dkhutch @atteggiani @Scott

HadGEM3 DeepMIP-Eocene ancillary files are available on NCI and @atteggiani has access to them. We also have their user guide to generate the ancillaries. Still, we could not recreate their ACCESS counterparts!

@dkhutch @Scott @MartinDix @Dietmar_Dommenget

Thanks Paul.

Interesting. @abhik Could you please point me to the HadGEM3 DeepMIP-Eocene ancillary files on NCI and the user guide? I want to narrow down the outstanding issues in ancillary generation.

Hi @paulleopardi, The datasets are in the /g/data/n69/sza565/ancil-from-uk/ directory on Gadi. If you can’t read n69 files, @atteggiani got access to this dataset and the user guide. Anyway, I am uploading the user guide here for any future reference.
Idiot’s guide to setting up GC3.1 Eocene suite on NEXCS v3.pdf (607.3 KB)

@Dietmar_Dommenget @dkhutch @Scott