COSIMA Working Group Meeting Minutes

Here are some brief minutes from today’s COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post (it’s a wiki post).

DATE: 09/02/2023
Attendees: 20-25

Small items:

  • ACCESS-NRI Compute Hours: Adele/Paul attended the ACCESS-NRI Science Advisory Committee and mentioned that the NRI has ~30MSU for distribution to the working groups (including the ocean-sea-ice working group - i.e. COSIMA) for science projects. If you’re interested please talk to Adele (or Andrew/Ryan who are the other ocean-sea-ice working group co-chairs). Preference would be for runs that are beneficial to the community, but other projects would be considered as well.

  • SWOT Linkage Project Awarded: Shane Keating et al. have been awarded a linkage project to work on SWOT and use it for improving surface current forecasting around Australia. Some possible sea ice work.

  • CMIP7 Scoping Workhop: Andy Hogg brought up the CMIP7 scoping workshop that will be held on the 28th Feb - 1st of March in Aspendale (and online). This will pull together the community to make decisions about a possible Australian CMIP7 contribution (who should run it, where we get storage, etc.).

  • Meeting minutes: Discussion of maintaining minutes for the COSIMA meetings, as is done for the COSIMA TWG meetings (this post). And speakers uploading their talks.

Talk: Alex Fraser from U Tas on “The Antarctic marginal ice zone: Satellite observations of MIZ width and wave attenuation” - lots of questions/discussion, including the possibility that ACCESS-OM3 (which will have coupled ocean-waves-sea ice) will be able to resolve an MIZ of some description.

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Brief minutes from the COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post (it’s a wiki post).

DATE: 02/02/2023
Attendees: ~20

Talk: Felipe Da Silva from U Tas on “Meanders in the ACC shape the air-sea heat fluxes and water subduction in ACCESS-OM2”.

COSIMA Hackathon Follow-up: Discussion of the successes and failures of last week’s COSIMA hackathon event. Navid took us through how to submit and review PR’s in cosima-recipes. See COSIMA Hackathon v2.0 -- Tuesday January 24th, 2023 for more details, in particular COSIMA Hackathon v2.0 -- Tuesday January 24th, 2023 - #44 by navidcy

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Here are some brief minutes from today’s COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post (it’s a wiki post).

DATE: 16/02/2023
Attendees: ~15

Talk: Zhaohui Wang from U Tas on “Intercomparison of Ice surface Temperature from Recent Global Atmospheric Reanalyses over Antarctic Sea Ice”, including a JRA-55, ERA-5 comparison.
Brief notes:

  • All reanalyses have very large warm biases in ice surface temperature over the Antarctic region. This is worse in ERA-5 than JRA-55. E.g. the area-averaged bias of JRA-55 is +1.39 K but the bias for ERA-5 is +6.24 K!
  • JRA55 performs well when cloud cover is low.
  • Biases linked to ERA5’s poor representation of clouds through excessive longwave radiation, as well as the representation of sea ice in the reanalyses (binary vs. fractional and ice thickness).
  • Andrew’s comment: ERA5 surface air temperature is also significantly warmer than JRA55, but JRA55-do corrections to JRA55 are excessive, resulting in SAT even warmer than ERA-5 in many places. See here, with more detail here.

ERA-5 in ACCESS-OM2 discussion:
• Ryan gave a summary of progress on an ERA-5 forced version of ACCESS-OM2. Slides can be found here.
• “naïve” ERA-5 forcing implemented with no adjustments, NCAR bulk formula, other simplifications.
• RYF simulations working and bulk circulation metrics and SST/SSS biases suggest they are looking good.
• IAF simulations running into technical issues that we hope to solve soon.
ERA-5do version is in the works from NCAR. Unclear what the time horizon is for this. COSIMA should engage with this as we have lots to contribute (Zhaohui’s work, ACCESS-OM2 as a test-bed).
• Will Hobbs brought up the point that being able to run the model at near real-time is really important for the Antarctic sea ice community. This will disappear sometime this year for JRA-55. So getting ERA-5 onboard is important, and there may be a big gap.
• Aidan pointed out that ACCESS-OM2 might make a great test-bed for new ERA-5 based products as it is well characterised and understood under JRA-55do forcing.

Some action items:

  • Make sure to engage with the NCAR/GFDL/ECMWF people who will develop ERA-5-do forcing.
  • We need more people looking at sea ice in the ERA-5 runs we have at the moment.

Discussion of ACCESS-NRI support for ACCESS-OM2 control runs pushed back to next week.

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Here are some brief minutes from today’s COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post (it’s a wiki post).

DATE: 23/02/2023
Attendees: ~35

Small items:
- NCI has a new upgrade in the works (Intel Sapphire Rapids) with many new CPUs available (as large as the current Cascade Lake nodes). 52 cores per node. We will be running a high-resolution 1/40-degree pan-Antarctic test on these runs that Adele and others are developing.

Tyler/Laurie/Pat validation of ACCESS-OM2-01-BGC: See this post for slides/follow-up

  • BGC fields in models can often be outside the error bars of the observations, and these error bars are already very large!
  • Negative bias in net primary productivity. One of lowest models. Also lower than ACCESS-ESM.
  • Larger seasonal cycle in NPP than observations - larger maximum bloom. However, the timing is good.
  • O2 → looks good! But initialized from 1979. Andy question: Do we see any trends? Yes but hard to say if it’s physical/expected or not.
  • DIC → mean bias but good gradients. Alkalinity similar as well.
  • Surface CO2 fluxes → overestimated, also issue with seasonal cycle. Spatial structure is good.
  • Mixed layer depth: Spatial structure is good. Some biases but no larger than differences between observational products.
  • Iron: Lots of drift in the positive direction. Questions: Is this the same in ACCESS-OM2-1? ACCESS-ESM? Would be good to compare across all of these.
  • There’s a need to continue the discussion here - possibly through another BGC-focused series of meetings see here

Levente Bodrossy (CSIRO Hobart) talk: See slides here
Extensive genomics dataset around Australia/Southern Ocean. Information on community composition. Interested in collaborating with BGC/ecosystem modellers who can potentially use this dataset as validation. Maybe not for WOMBAT (only one phytoplankton class). However, Tyler suggested it could be used to check/validate the growth rate parameters used in WOMBAT.

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Here are some brief minutes from today’s COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post (it’s a wiki post).

DATE: 02/03/2023
Attendees: ~30

Update from CMIP7 scoping workshop from Adele:

  • The community wants to put in a CMIP7 submission, because:
    • Critical for credibility of our model
    • Catalyses model development
    • Otherwise might have to co-op another model
  • Timeline: IPCC data deadline - mid 2025-end of 2026. Simulations start mid-2024-end 2025.
  • Model configuration:
    • Ambitious option: ACCESS-CM3 → MOM6, CICE6, UM updates/latest. + ESM3 carbon cycle version.
    • Some doubt within the carbon-cycle community if there is enough time to spin-up given tight timeline.
    • Possible backup: Model based on ACCESS-CM2.
  • No definitive decision. Small working group put together to make a decision/write something up.
  • What this means for COSIMA:
    • Starting simulations mid next-year means there would be a need for COSIMA input to develop MOM6-CICE6 global. We might need to refocus on the global configuration rather than the regional.
    • Benefits to COSIMA from buying into this development of ACCESS-CM2 (from NRI).
  • Andy: Need to be ambitious to convince government to give money to support this.

Wilma Huneke Talk: Australia’s ACCESS-CM2 climate model with a higher-resolution ocean-sea ice component (1/4°)

  • Overview of ACCESS-CM2 with 1/4-degree ocean - comparison to observations and ACCESS-OM2.
  • Costs: 12.5kSU/model year, 4.3yr/day on 1152 cores. (Comment from Adele: This is still really fast despite 1/4-degree ocean. Possible we could go to 1/10-degree. However - benefit from increasing atmospheric resolution might be larger.)
  • Clear improvement in oceanic variability metrics. However, no clear improvement (and often things get worse) in mean state biases.
  • Much of SST bias thought to come from atmosphere.
  • Large multi-decadal variability in the North Atlantic in CM2-025 that is not present in CM2-1. Overtakes ENSO as the largest mode of variability.
  • Andrew K question: How are the fluxes exchanged? Low-res atmosphere means blocky fluxes. There is another approach called “exchange grids” that could help with this.

Aidan on NRI support for ACCESS-OM2 Control runs: See ACCESS-OM2 Control Runs
What should the NRI support in terms of ACCESS-OM2 control runs?

What does support mean:

  • Take over control of data (frees up space for COSIMA).
  • Clean-up of data and documentation/reproducibility (e.g. restarts, configurations).
  • Classes of support:
    • Legacy: If issues are found then flag them. If the issue is big then retract the data.
    • Full support: Rerun the simulations if issues are found during period of full support (TBD)

From the COSIMA side:

  • Would be great to have “legacy”-style support for the RYF/IAF 1/10th degree simulations (these are the biggest in terms of data). Start with those, then move onto 1/4 and 1-degree RYF/IAF.
  • One potential issue is that in the 1/10th many diagnostics are only available for portions of the run. Harder to support.

@wghuneke Feel free to post your diagnostic plots in this thread, or probably better a new one and link back here, to get some detailed feedback.

Here are some brief minutes from today’s COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post (it’s a wiki post).

DATE: 02/03/2023
Attendees: ~20

Small items:

  • Ryan will step down from running the weekly meetings and from the NRI working group co-chair from the end of March. Paul Spence and Ed Doddridge will step in as additional co-chairs (with Adele and Andrew), and take over the weekly meetings.
  • COSIMA will start to focus on the global OM3 configuration to align with CMIP7 plans. Dougie has put together a working initial version of CESM with the NuOPC coupler on Gadi. See GitHub - COSIMA/access-om3: ACCESS-OM3 global ocean - sea ice - wave coupled model if you’re interested in contributing.

Talk: Sebastian McKenna (UNSW): How Pacific Ocean SST biases impact the Indian Ocean using pacemaker experiments in ACCESS-CM2

  • Planned pacemaker experiments that remove ENSO, or remove the mean SST bias, in the Pacific to see impacts on Indian ocean mean and variability.
  • Initial experiments where SST in the Pacific is replaced by model climatology (removing ENSO) show minimal impacts on mean SST elsewhere, except in the North Atlantic which is a sensative area (could be just model internal variability).
  • Discuss of whether this could be linked to weak ENSO diversity/asymmetric in ACCESS-CM2.
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Here are some brief minutes from today’s COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post (it’s a wiki post).

DATE: 23/03/2023
Attendees: ~32 + group in-person at ANU

Small items:
• There aren’t many SUs left on any accounts. Pedro will use anything you have available.

Talk: “How can we better understand what is happening in the Southern Ocean and Antarctica: Existing ECCO ocean reanalyses and ECCO downscaling simulations” by visiting Japanese Assistant Professor Yoshihiro Nakayama as part of the Australia-Japan Science and Innovation Partnership, see
Recording: COSIMA Meeting 23/03/2023 - Yoshihiro Nakayama Talk - YouTube

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Here are some brief minutes from today’s COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post (it’s a wiki post).

DATE: 30/03/2023
Attendees: 35

Small items:
• Qian, Matt, Andy, Adele and Steve have a nice paper out in Nature on melt-water driven slowdown in AABW using ACCESS-OM2-01: Torrents of Antarctic meltwater are slowing the currents that drive our vital ocean 'overturning' – and threaten its collapse, Abyssal ocean overturning slowdown and warming driven by Antarctic meltwater | Nature
• Discussion of having the annual COSIMA meeting along with the ACCESS-NRI community meeting in Canberra. September 4th-8th as possible dates.
• Short update on ERA-5 run from Ryan. See for more details. Will Hobbs commented that for the sea-ice Near-Real Time stuff they probably only need 1/4-degree.
• ACCESS-OM3 configuration progress - will hopefully have something for people to test soon.
• There won’t be a COSIMA meeting next week. Still looking for a speaker for the following week. Talk to Paul and Ed who are taking over from now on.

Talk: Ariaan Purich “The Southern Ocean Freshwater Initiative” (SOFIA) A SO meltwater MIP. Slides:
APurich_COSIMA_230330.pdf (5.3 MB)
See EGUsphere - The Southern Ocean Freshwater release model experiments Initiative (SOFIA): Scientific objectives and experimental design for the paper preprint.

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Here are some brief minutes from today’s COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post.

Date: 20/04/2023

Ed Doddridge published a nice article on Southern Ocean sea ice in the conversation:

James Wyatt gave an excellent talk titled “Making the most of satellite and Southern Ocean observations – an updated Gravest Empirical Mode”. :partying_face: He is using ARGO data and satellite SSH to understand ACC dynamics. Youtube link for those who missed it: James Wyatt (2023-04-20) - YouTube

We had a speaker cancellation and are looking for a speaker for next week :poop:

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Here are some brief minutes from today’s COSIMA meeting. If I’ve missed anything you feel is important please feel free to add it below or edit this post.

Date: 27/04/2023

Felipe DaSilva gave an excellent talk on his published honours thesis " [On the Deep Western Boundary Current Separation and Anticyclone Genesis off Northeast Brazil]"(

We perused the recent JPO issue: Journal of Physical Oceanography | AMETSOC

We also discussed how to get a more diverse range of questions and questioners during our discussions. Common reasons why folks are reluctant to ask questions are power structures, fear of embarrassment, low confidence and shyness. We are trialling a few options to counter these barriers: i) dedicated space for ECR folks to ask questions (consensus that this is an okay idea, ii) awards for asking questions (based on a ridiculous points system with no consensus on if this is a good idea).

Sincere thanks to all the ECRs who jumped in and asked questions today!!! Let’s keep it going!!!

Youtube link for Felipe’s talk: Felipe de Silva (2023-04-27) - YouTube

Notes from COSIMA meeting on 04-05-2023

Yue Sun gave an introduction to Oceananigans and demonstrated some example notebooks that run on Gadi. Yue Sun (2023-05--04) - YouTube

Chengyuan Pang spoke about “Remote energy sources for mixing in the Indonesian Seas” Chengyuan Pang (2023-05-04) - YouTube

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Notes from the COSIMA meeting on 18-05-2023.

@AndyHoggANU led a short discussion on CMIP7 and ACCESS-OM3 development.

@lidefi87 told us about OceanHackWeek. If you’re interested in attending (either as a participant or a mentor), check it out here:

After that, @ashjbarnes knocked our socks off with a live demonstration of some regional modelling tools for MOM6. Even though audience participation led to an awkwardly skinny domain with lots of land in it, the tools were amazing.
Watch the talk: Ashley Barnes (2023-05-18) - YouTube
access the tools: GitHub - COSIMA/mom6-regional-scripts: Scripts for cutting out regional boundary forcing for MOM6

Notes from COSIMA meeting on 25-05-2023.

We listened to a radio interview @edoddridge gave on ABC Radio National’s AM: 'Gobsmacking': Antarctic sea ice shrinks - ABC Radio

Yinghuan Xie presented “Exploring the Euphotic Zone Residence Time for Lower Cell Water Mass” Yinghuan Xie (2023-05-25) - YouTube

Notes from COSIMA meeting on 01-06-2023.

Reminder that dates for this year’s COSIMA meeting have been finalised. See this post from Adele: COSIMA VII Workshop 2023 - #2 by adele157

We heard from Ram Patel about eddy transports in observations and models. Youtube link to come.

COSIMA meeting 2023-06-08 minutes

  1. AMOS meeting session proposals close 9 June. Short discussion about COSIMA presence at upcoming AMOS 2024 in Canberra.
    If you are interested in helping to organise a high-latitude climate and processes session, contact Ariaan Purich.

  2. Recurring calendar event. Ed is working on this, and it should be good to go for next week.

  3. upcoming OM3 development meeting.
    Proposed 1 hour meeting. Might be a COSIMA slot. Anyone who wants to be involved, get in touch with Adele, Andrew, Ed, or Paul.

  4. Yuhang Liu presented some great science about bottom roughness and heat transport. Youtube link coming soon.

Notes from COSIMA meeting on 22-06-2023

Announcement about the upcoming COSIMA workshop in Canberra. Forum topic here for more details: COSIMA VII Workshop 2023


  • Monday will have an ACCESS-OM3 development day / hackathon, or training sessions from ACCESS-NRI and NCI.
  • Tuesday and Wednesday will be ACCESS-NRI community workshop.
  • And then the main event - COSIMA workshop on Thursday and Friday.

There’s a lot going on for the whole week, so if you can, we encourage you to attend for the whole week.

@AndyHoggANU led a discussion on ACCESS-OM3 development. If you missed it, you can catch up here:

Notes from COSIMA meeting on 29-06-2023

Reminder to register for upcoming COSIMA and ACCESS-NRI workshop in Canberra. More info here: COSIMA VII Workshop 2023

Xihan Zhang gave a fabulous talk “Maintenance of the zonal momentum balance of the Antarctic Circumpolar Current (ACC) by barotropic dynamics”

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Notes and links from recent COSIMA meetings.

I fell behind in uploading the recordings and sharing the links. Sorry. In compensation, here is an omnibus of exciting ocean science talks that should help dispel the Monday blues.

Ram Patel - Insight into Southern Ocean eddies from historical observations: Ram Patel (2023-06-01) - YouTube

Yuhang Liu - Seafloor roughness reduces melting of the Antarctic ice sheets: Yuhang Liu (2023-06-08) - YouTube

Maya Jakes - Subduction and ventilation via finescale filaments: Maya Jakes (2023-07-06) - YouTube

Ole Rieke - Interannual variability of basal melt rates in the Amundsen Sea: Ole Rieke (2023-08-03) - YouTube

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Here’s the link to the recording of today’s presentation by Quanling Deng:

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