# Session 5: Model development options **URL:** \ **Category:** CMIP7 Workshop\ **Tags:** workshop, cmip7\ **Created:** [28 February 2023 21:30 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504 "2023-02-28T21:30:04Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![NBateman-bit](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/nbateman-bit/32/45_2.png) [@NBateman-bit](https://forum.access-hive.org.au/u/NBateman-bit)\ **Post date:** [28 February 2023 21:30 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/1 "2023-02-28T21:30:04Z")
This topic contains discussions, questions and thoughts for Session 5 of the CMIP7 Workshop Time and Date: Wednesday 01 March, 2023 from 9:00 - 10:45 am ---
**Author:** ![NBateman-bit](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/nbateman-bit/32/45_2.png) [@NBateman-bit](https://forum.access-hive.org.au/u/NBateman-bit)\ **Post date:** [28 February 2023 22:01 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/2 "2023-02-28T22:01:11Z")
Chair: Kelsey Druken Speakers and topics: Australia’s CMIP6 configurations: ESM1.5, CM2, OM2 + future possible configurations (Tilo Ziehn, CSIRO, 10+5 min) OM3 (Adele Morrison, ANU, 10+5 min) CABLE/POP (Ian Harman, 10+5 min) Ice sheet modelling (Ben Galton-Fenzi, Australian Antarctic Division (AAD), 10+5 min) Atmospheric Chemistry (Matt Woodhouse, CSIRO, 10+5 min) Model evaluation (Gab Abramowitz, UNSW,10+5 min) Tropical variability Modelling (Shayne McGregor, Monash University, 10+5 min) ---
**Author:** ![AndyHoggANU](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/andyhogganu/32/43_2.png) [@AndyHoggANU](https://forum.access-hive.org.au/u/AndyHoggANU)\ **Post date:** [28 February 2023 22:11 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/3 "2023-02-28T22:11:03Z")
Just to update Tilo’s numbers on OM2 compute requirements: ACCESS-OM2 (1°) - 288 cores, 96 yrs/day ACCESS-OM2-025 (0.25°) - 1824 cores, 12.2 yrs/day ACCESS-OM2-01 (0.1°) - 12,144 cores, 3.7 yrs/day … ---
**Author:** ![heidi](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/heidi/32/335_2.png) [@heidi](https://forum.access-hive.org.au/u/heidi)\ **Post date:** [28 February 2023 22:18 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/4 "2023-02-28T22:18:18Z")
Tilo Ziehn: Possible New configurations: ![newConfis](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/6f4e4c4ff3445014ab9efdc787e4f26a4d92d812.jpeg) ---
**Author:** ![heidi](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/heidi/32/335_2.png) [@heidi](https://forum.access-hive.org.au/u/heidi)\ **Post date:** [28 February 2023 22:31 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/5 "2023-02-28T22:31:38Z")
Adele Morrison: MOM6 vs MOM5 ![mom6vsmom5](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/15d9637763f13d0ff731121c8311327cdfc19dfa.png) ---
**Author:** ![heidi](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/heidi/32/335_2.png) [@heidi](https://forum.access-hive.org.au/u/heidi)\ **Post date:** [28 February 2023 22:33 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/6 "2023-02-28T22:33:02Z")
Adele Morrison: ACCESS-OM3 progress ![access-OM3progress](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/ecfd68c20855689a134875110e8fdc5cc3f98f8f.jpeg) ---
**Author:** ![AndyHoggANU](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/andyhogganu/32/43_2.png) [@AndyHoggANU](https://forum.access-hive.org.au/u/AndyHoggANU)\ **Post date:** [28 February 2023 22:42 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/7 "2023-02-28T22:42:24Z")
Just to briefly answer Shayne’s question on hybrid coordinates in MOM6. The way MOM6 timesteps is that the horizontal dynamics is separated from vertical dynamics. The vertical dynamics allows you to regrid to any vertical coordinate you choose, and thus gives you complete flexibility of the vertical coordinate — it’s just up to you to provide a nice algorithm on how to do that regridding. We are currently testing z-star, terrain-following, quasi-isopycnal, hybrid (i.e. z-star merged with isopycnal) and adaptive… ---
**Author:** ![heidi](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/heidi/32/335_2.png) [@heidi](https://forum.access-hive.org.au/u/heidi)\ **Post date:** [28 February 2023 22:50 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/8 "2023-02-28T22:50:13Z")
Ian Harman: Possible ACCESS land configurations in CMIP7: ![landConfigCMIP7](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/7ef4a682e3529dac4f7192f263dd81893d746681.jpeg) ---
**Author:** ![aekiss](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/aekiss/32/46_2.png) [@aekiss](https://forum.access-hive.org.au/u/aekiss)\ **Post date:** [28 February 2023 22:53 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/9 "2023-02-28T22:53:38Z")
Comment to Ian: NUOPC has the flexibility to support a land BGC model split into 2 components coupled with different frequency ---
**Author:** ![MATTENGLAND](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/mattengland/32/451_2.png) [@MATTENGLAND](https://forum.access-hive.org.au/u/MATTENGLAND)\ **Post date:** [28 February 2023 22:54 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/10 "2023-02-28T22:54:50Z")
Nice idea Andy to see if enhanced vertical OGCM resolution (or maybe you meant different vertical coordinate schemes?) will solve the biannual ENSO - easily testable with a ~20-yr simulation in coupled mode. Would be good to test. In COSIMA we spend most of our time in uncoupled mode, this is a great problem to solve across the ocean and atmosphere modelling communities. e.g. maybe it’s the AGCM convection scheme? Or both that and OGCM resolution (etc). ---
**Author:** ![MATTENGLAND](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/mattengland/32/451_2.png) [@MATTENGLAND](https://forum.access-hive.org.au/u/MATTENGLAND)\ **Post date:** [28 February 2023 23:06 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/11 "2023-02-28T23:06:37Z")
Re. ice sheet processes and meltwater, in case you’re wondering if this matters for CMIP projections, here’s the impact of added MW (high end scenario) in the GFDL projections (taken from [Change in future climate due to Antarctic meltwater | Nature](https://doi.org/10.1038/s41586-018-0712-z)): ![image](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/665eb7104c140be4caba7d3cc8fd5c75cbf1eee1.jpeg) ---
**Author:** ![heidi](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/heidi/32/335_2.png) [@heidi](https://forum.access-hive.org.au/u/heidi)\ **Post date:** [28 February 2023 23:11 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/12 "2023-02-28T23:11:06Z")
Ben Galton-Fenzi: Ice sheets and climate interactions: ![icesheetsClimateInteract](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/7aecf8a071f58e15fb6885851909998ee7f2f577.jpeg) ---
**Author:** ![heidi](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/heidi/32/335_2.png) [@heidi](https://forum.access-hive.org.au/u/heidi)\ **Post date:** [28 February 2023 23:11 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/13 "2023-02-28T23:11:58Z")
Ben Galton-Fenzi: Concluding remarks: ![ConcludingPts](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/b3a71c719600253c876aec0e1a7d1164bd9cc1bc.jpeg) ---
**Author:** ![Aidan](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/aidan/32/42_2.png) [@Aidan](https://forum.access-hive.org.au/u/Aidan)\ **Post date:** [28 February 2023 23:15 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/14 "2023-02-28T23:15:07Z")
Matt Woodhouse: Is there a definition of “nudging”, and how it differs from “full data assimilation”? Or are they same thing with a different name? ---
**Author:** ![heidi](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/heidi/32/335_2.png) [@heidi](https://forum.access-hive.org.au/u/heidi)\ **Post date:** [28 February 2023 23:27 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/15 "2023-02-28T23:27:17Z")
Matt Woodhouse: Chemistry and Aerosol in ACCESS ![chemAerosolACCESS](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/693e66ddbf0945caadae33f39d2a221e9527697c.jpeg) ![GLOMAP](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/692b1b34708d21111c64802406dcd996aa247e83.jpeg) ![DiscussionChem](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/1e9eb33a1e4452089bc134c9389f72f4ce326c3c.jpeg) ---
**Author:** ![Aidan](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/aidan/32/42_2.png) [@Aidan](https://forum.access-hive.org.au/u/Aidan)\ **Post date:** [28 February 2023 23:36 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/16 "2023-02-28T23:36:47Z")
@gab recommended reading these papers > **[Johannes Lenhard & Eric Winsberg, Holism, entrenchment, and the future of...](https://philpapers.org/rec/LENHEA)** > > In this paper, we explore the extent to which issues of simulation model validation take on novel characteristics when the models in question become particularly complex. Our central claim is that ... > **[The Numerical Implementation of Land Models: Problem Formulation and Laugh Tests](https://journals.ametsoc.org/view/journals/hydr/22/6/JHM-D-20-0175.1.xml)** > > Abstract The intent of this paper is to encourage improved numerical implementation of land models. Our contributions in this paper are twofold. First, we present a unified framework to formulate and implement land model equations. We separate the... ---
**Author:** ![Aidan](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/aidan/32/42_2.png) [@Aidan](https://forum.access-hive.org.au/u/Aidan)\ **Post date:** [28 February 2023 23:39 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/17 "2023-02-28T23:39:24Z")
@gab mentioned unit testing: my comment **HALLELUJAH!** ---
**Author:** ![bgf](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/bgf/32/455_2.png) [@bgf](https://forum.access-hive.org.au/u/bgf)\ **Post date:** [28 February 2023 23:41 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/18 "2023-02-28T23:41:38Z")
@gab - nice talk. I think that just because we can make a part better, should we make that part better or move elsewhere? Obvious and substantive errors should be fixed of course, or avoided in the first place. I think about your approach as trying to optimise the model but “How good is good enough?” is perhaps something we should also be asking more often and of each other? This helps define the measure of how we can efficiency. ---
**Author:** ![heidi](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/heidi/32/335_2.png) [@heidi](https://forum.access-hive.org.au/u/heidi)\ **Post date:** [28 February 2023 23:46 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/19 "2023-02-28T23:46:40Z")
Gab Abramowitz: Model evaluation: ![confirmationHolism](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/7d2069dcc086fb3b9c06fe20329f55a7c8db8f19.jpeg) ![evaluationTools](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/f510d638217a20b6f1ab198985134bd044a8289c.jpeg) ![unitTesting](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/2872b3c4168f0031787bbbe486a0577ebd97212a.jpeg) ---
**Author:** ![aekiss](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/aekiss/32/46_2.png) [@aekiss](https://forum.access-hive.org.au/u/aekiss)\ **Post date:** [28 February 2023 23:52 UTC](https://forum.access-hive.org.au/t/session-5-model-development-options/504/20 "2023-02-28T23:52:25Z")
Re. Gab’s talk - FYI this is the testing approach being taken in CICE: [http://dx.doi.org/10.1098/rsta.2017.0344](http://dx.doi.org/10.1098/rsta.2017.0344) > Changes, additions and updates to CICE fall into four categories: (I) BFB [bit-for-bit] with no further assessment required; (II) non-BFB but unlikely to be climate changing; (III) non-BFB and climate changing; and (IV) a new model configuration option requiring separate scientific assessment. [This paper] describes the automated methods used to flag the first three categories [Next page](https://forum.access-hive.org.au/t/session-5-model-development-options/504.md?page=2)