Mirko submitted major refactoring update to the nudging code for MOM. Three different options depending on namelist. One just sponge, one does nudging, another does adaptive nudging. Added instantaneous update from datafile. Wanted to reproduce the MOM4 behaviour. Tested, and now works. Was broken previously.
Can merge, but we need some testing on other coverage. Currently have a dozen test cases. Not sure any touch this, but will run them anyway. Justin suggests they provide a test case which covers some of these sections.
Nic asked that if possible functional and formatting changes be separate commits, as it makes approving pull requests much easier
Maybe not merge yet, but get testing working to cover this. Justin will look at adapting an existing MOM test case for this purpose.
Exchange grids and smoothing
Justin was talking to Paul Sandery about exchange grids. An issue with tiling as a result of remapping. Was asking about how Russ implemented smoothing.
If you took interim fields end up with horrible pattern with convergence of winds with 1st or 2nd order remapping due to discontinuity. Russ wrote some code that does 2D smoothing within the surface boundary condition. Bypasses the exchange grid and used the flux exchange to native grids options(?). GFDL apply an interpolation when they read in via data override. So can use the data override to interpolate to the finer grid and can control this.
This is only a problem with conservative remapping with exchange grids.
Nic didn’t think this was a problem with standard MOM-SIS runs, but Russ said it should still be visible in the fluxes with coarse (1deg) forcing fields.
With ACCESS high res ocean the fields and fluxes are extremely blocky, so Nic smooths on the ice grid, before it comes into the ocean grid, on a tile by tile basis.
If you want local conservation, cannot get around this. In ACCESS can use linear interpolation and then post-process to get global conservation. Doesn’t work with local conservation.
Marshall suggested we have some test cases that don’t run the model but test coupling and fields
These effects most often seen when there is a big difference in resolution between model fields and input fields. Look at wind stress fields. Maybe some of the barotropic fields, height and definitely convergence in barotropic restart file.
Paul’s runs do not use conservative remapping. Don’t see the horrible features with some of the other schemes.
Nic: do we need a central document discussing this?
Justin is trying to prototype OceanMaps 4. Picking up on Paul Sandery’s work. He has been using MOM5-SIS and using bulk fluxes to link the models. Would like to standardise, or make these things available. Not sure how it connects to linkage project.
Nic felt it was good to know what Paul does. So far no code changes?.
Aidan got a query from Dave Hutchinson, asking if latest version of FMS was included in the code on MOM5 repo. Marshall has updated FMS in the master branch to Ulm, but not to Verona, the latest version.
Move FMS to a submodule of MOM5 rather than manually included inline
Goal is for Rui Yang (NCI) to work on parallel netCDF in MOM5
Model release naming and definition
Still an issue
Nic has put an access-om model on OceansAus. Has version controlled input files and code. Can be downloaded, compiled and run.
ACCESS-OM models are using CICE4.?, but Peter is using 5.1.
There are many bug fixes and performance improvements in the version of CICE Nic has been working on that would be beneficial to Peter.
Peter is working on a refactoring of CICE5.1
We should align our work to the same version of CICE.
First step is for Peter’s version of CICE5.1 to be hosted on OceansAus and development work to be based from that so we can work together. Some discussion about the best way to do this.
Just and Mirko work up test cases to cover the nudging code and give them to Nic.
Nic to add new test cases to Jenkins test suite.
Aidan to add mom-ocean.org and mom-ocean.org.au to uptime monitoring service (Uptime Robot).
Add Peter’s CICE5.1 config to OceansAus github repo
Nic create a discussion document (on COSIMA?) to document current approaches and strategies for future
Marshall to move FMS to submodule of MOM5 github repo. Liase with Nic on implementation?
Others test Nic’s access-om model config on OceansAus
The first meeting of the Consortium for Ocean Sea Ice Modelling in Australia (COSIMA) was held in Hobart on the 26-27 May 2016. There we 38 attendees (20 of whom gave presentations), representing 10 different institutions. A full participant list is included at the end of this report.
The goal of the workshop was to formalise a consortium across universities, BoM, AAD and CSIRO to build global model configurations that will form the basis for high-resolution forecasting, reanalysis, process modelling and ultimately coupled climate modelling. The consortium recently received 4 years of funding from an ARC Linkage Project to build a model configuration which underpins a variety of applications.
Presentations included an update on the current status and near-term plans of the major modelling groups, recent scientific advances using ocean and sea ice models and highlights of technical advances in model development. Some edited highlights are listed below:
Uptake of the MOM5 model for global applications has progressed well in the last 5 years (Bi). It is currently used broadly across climate and ocean-only configurations at both 1° (O’Kane) and 0.25° resolution (Spence, Holmes). Developments at 0.1° are proceeding (Zhang, Langlais, Matear, Chamberlain, Hogg).
Other models with a strong user base in Australia include ROMS (Galton Fenzi) for near-coastal and near-Antarctic applications, MITgcm for regional GFD-style simulations (Nikurashin) and NEMO (Alves) for seasonal prediction.
There is a strong need to consider vertical resolution in future high resolution model developments (Stewart).
The CICE sea ice model, while no longer under active development at LANL, continues to be the ice model of choice (due primarily to its superior ice physics over SIS 1; Heil, Reid, Bennetts). It is likely that it will remain the model of choice with applications using MOM5.
Our MOM-CICE implementations using OASIS3-MCT coupling, but it is not clear that this solution will scale to 0.1° and beyond (Hannah)
MOM6 is rapidly developing, and is beginning to gather users within Australia. It looks viable to use MOM6 for global models in the next year or two (Griffies, Gibson).
MOM6, being a C-grid model, presents some challenges when working with a B-grid ice model such as CICE. For the time being, it seems that the best ice model to use with MOM6 will be SIS2, which is actively being developed at GFDL to incorporate the vertical physics (Griffies).
Computational performance of these models shows that MOM5 is marginally faster than MOM6 (once accounting for vertical resolution differences) and that both models scale well on Raijin. NEMO is faster at small core counts but scales poorly (Ward).
Forced ocean-sea ice models should be transferring to the JRA-55 forcing set when possible (Marsland).
The COSIMA Community
There was significant support for the formation of a community of ocean-sea ice modellers around the COSIMA banner:
Need to create a website to outline COSIMA activities and developments. [We are in the process of acquiring the domain name cosima.org.au, and ANU will fund hosting and a web development team to put together a skeleton site.]
We will formalise a code of ethics for COSIMA users to abide by, based on the DRAKKAR agreement. [Spence]
We aim to register members on the website, and create a mailing list
We will need to formalise the use of technologies to share code configurations, analysis tools and data. It may be possible to have a data project code on NCI to help with this.
We will release flagship configurations that are broadly supported by the community. The goal is to make the naming conventions consistent with the ACCESS community where possible, and to overlap with ACCESS developments where possible.
COSIMA will hold an annual meeting in the last week of May, for two days. Venue will rotate around the partner institutions. The focus of the meeting will be on science applications of ocean models, but will also include a technical component.
We will aim to have more regular communications, including newsletters and video meetings.
We will establish working groups within the community, along with a working group chair. Proposed groups include
Sea Ice Modelling [Heil]
Linkage Project [Hogg]
The major gap in the community was identified to be sea ice modelling and forecasting. We will all look for opportunities to attract visitors and expertise in this space.
One of the workshop goals was to receive advice from the community regarding the ARC Linkage Project designed to support COSIMA development activities. Major items of discussion were:
There was general agreement that the Linkage Project should fund both the development and evaluation of new model configurations. This point implies that we should equally fund the technical and postdoctoral position, despite the partial funding of the program.
In the first year we will look to upgrade current MOM5 implementations, focussing on the vertical grid and the incorporation of CICE.
In subsequent years we will look to adopt a MOM6 configuration.
As configurations develop and have been properly evaluated, they will be distributed to the community.
Suggestions on evaluation include using ESMVal.
(Where available, talk files are linked from the presenter’s name.)
This detailed animation of the movement of the densest and coldest water in the world around Antarctica has been produced using data generated on Australia’s most powerful supercomputer, Raijin.
So much data was used, that it took seven hours to process just one second of the animation.
The visualization has revealed underwater ocean storms generated by eddies, waterfalls of cold dense water that plummet two kilometres off the Antarctic Continental Shelf into the abyss and underwater waves hundreds of metres high.
This latest animation peels back much of the surface layer of the ocean to explore how the cold dense water produced on the Antarctic continental shelf spreads out into every ocean basin in the world.
The movement of this dense water is vital. It is the most oxygenated water in the ocean and its extreme density and coldness drive many of the significant currents in the major ocean basins connected to the Southern Ocean.
The distinctly different densities of water that move around Antarctica also make it important in regards to climate change. Because the most dense water forms near the surface of Antarctica before descending to the ocean floor, any warming that occurs near the surface can be drawn down into the deep ocean.
Importantly, this drives more heat and more carbon into the deep ocean that would otherwise have returned to the atmosphere.