# ERA-5 forced ACCESS-OM2 simulations **URL:** \ **Category:** COSIMA\ **Created:** [21 August 2023 04:00 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103 "2023-08-21T04:00:45Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![rmholmes](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/rmholmes/32/117_2.png) [@rmholmes](https://forum.access-hive.org.au/u/rmholmes)\ **Post date:** [21 August 2023 04:00 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/1 "2023-08-21T04:00:45Z")
Hi everyone, This is a post to document some details for the ERA-5 forced ACCESS-OM2 runs that I have completed to a state which I’m happy to share. I’m hoping others with an interest can jump in and do some analysis. Hopefully the runs will be useful to someone! Note that these runs are still somewhat of a work in progress. There are a number of known issues which have not been addressed yet (see @aekiss’s post at [Support ERA5 forcing · Issue #242 · COSIMA/access-om2 · GitHub](https://github.com/COSIMA/access-om2/issues/242#issuecomment-1487906161)). Documentation of the steps taken and problems that have been solved are at [Support ERA5 forcing · Issue #242 · COSIMA/access-om2 · GitHub](https://github.com/COSIMA/access-om2/issues/242). That said, the results I’ve looked at so far seem reasonable. I’ve done 4 ERA-5 runs (RYF and IAF, 1-degree and 1/4-degree), with 4 equivalent JRA55-do forced runs for comparison, with details listed in the below table. Initial analysis of some basic metrics can be found [here for the IAF](https://github.com/rmholmes/cosima-scripts/blob/master/ERA-5/ERA-5_Initial_Analysis-IAF.ipynb) and [here for the RYF](https://github.com/rmholmes/cosima-scripts/blob/master/ERA-5/ERA-5_Initial_Analysis-RYF-clean_redo.ipynb). Please feel free to expand on these and share your findings here! Thanks to @aekiss, @russfiedler, Nic Hannah, @Aidan and probably a bunch of other people I’ve missed for their contributions. _Edit, 24/03/2025_: There is now one more additional run of the 1/4-degree IAF simulation through a full cycle, from 1958-forwards. Note that this run has a more extensive set of diagnostics (including heat budget outputs), but output in the old format of multiple variables in a few files. | Run name | Time period | Data location in `/g/data/ik11/outputs/` | Configuration | | --- | --- | --- | --- | | **IAF Runs** | | | | | `025deg_era5_iaf_1958cycle1` | 1958 to end of 2023 | `access-om2-025/025deg_era5_iaf_1958cycle1` | [GitHub - rmholmes/025deg\_era5\_iaf at 1958start\_cycle1](https://github.com/rmholmes/025deg_era5_iaf/tree/1958start_cycle1) | | `025deg_era5_iaf` | 1980 to end of 2023 | `access-om2-025/025deg_era5_iaf` | [GitHub - rmholmes/025deg\_era5\_iaf](https://github.com/rmholmes/025deg_era5_iaf) | | `025deg_jra55v150_iaf` | 1980 to end of 2023 | `access-om2-025/025deg_jra55_iaf_era5comparison/` | [GitHub - rmholmes/025deg\_jra55\_iaf at jra55v1501](https://github.com/rmholmes/025deg_jra55_iaf/tree/jra55v1501) | | `1deg_era5_iaf` | 1960 to 2019 | `access-om2/1deg_era5_iaf` | [GitHub - rmholmes/1deg\_era5\_iaf at ryan\_testing](https://github.com/rmholmes/1deg_era5_iaf/tree/ryan_testing) | | `1deg_jra55_iaf` | 1960 to 2020 | `access-om2/1deg_jra55_iaf_era5comparison` | [GitHub - rmholmes/1deg\_jra55\_iaf at era5comp](https://github.com/rmholmes/1deg_jra55_iaf/tree/era5comp) | | **RYF Runs** | | | | | `1deg_era5_ryf` | 100 years | `access-om2/1deg_era5_ryf` | [GitHub - COSIMA/1deg\_era5\_ryf](https://github.com/COSIMA/1deg_era5_ryf) | | `1deg_jra55_ryf` | 100 years | `access-om2/1deg_jra55v14_ryf` | [GitHub - rmholmes/1deg\_jra55\_ryf at era5comp](https://github.com/rmholmes/1deg_jra55_ryf/tree/era5comp) | | `025deg_era5_ryf` | 21 years | `access-om2-025/025deg_era5_ryf` | [GitHub - COSIMA/025deg\_era5\_ryf](https://github.com/COSIMA/025deg_era5_ryf) | | `025deg_jra55_ryf` | 20 years | `access-om2-025/025deg_jra55_ryf_era5comparison` | [GitHub - rmholmes/025deg\_jra55\_ryf at era5comp](https://github.com/rmholmes/025deg_jra55_ryf/tree/era5comp) | ---
**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:** [21 August 2023 05:35 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/2 "2023-08-21T05:35:45Z")
Awesome, thanks @rmholmes! ---
**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:** [21 August 2023 05:44 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/3 "2023-08-21T05:44:51Z")
Great work Ryan! I took a look at the notebooks, what would you say are the best and worst features of the ERA5 forced experiments? Some things I noticed (as I am sure anyone else who took a look): ## RYF - Scalars all look pretty similar, except for global mean temperature where ERA5 starts drifting earlier, but rates of drift look similar - Drake passage transports in 1-deg ERA5 never go as low and recover more quickly. 0.25 look the same - Arctic ice much lower for ERA5, though trends look similar. - Antarctic ice higher for ERA5, though trends look similar - Arctic summer minimum much lower for ERA5 - Over-turning metrics didn’t plot correctly ## IAF - Scalars all look pretty similar, except for 1-deg global mean temperature where ERA5 drifts down but stabilises and then rates of drift look similar ![iaf_global_mean](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/0d5d3716fa082590982963c1db9e3e4999a6dec8.png) - 1 degree ACC Transport is a bit odd, where ERA5 takes off, then comes back down around 1980 and basically shadows the JRA55 value until they start to diverge a little from 2010 ![iaf_acc](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/d64c4a1093d66d8cf83ac4fbe959008b91eebf3d.png) - Antarctic ice slightly higher for ERA5, though trends look similar. Winter maximum a fair bit higher for ERA5 - Arctic ice lower in ERA5, and summer minimum much lower for ERA5 (Arguably [too low](https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/)?) ![iaf_sea_ice](https://us1.discourse-cdn.com/flex020/uploads/access1/original/1X/2ce87430acc41b6e4c74f9bd5d6fe8a09c596c99.png) Edit: included @rmholmes figures inline, which I should have done originally ---
**Author:** ![rmholmes](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/rmholmes/32/117_2.png) [@rmholmes](https://forum.access-hive.org.au/u/rmholmes)\ **Post date:** [21 August 2023 06:54 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/4 "2023-08-21T06:54:54Z")
Thanks @Aidan. The relatively consistent drifts in global T is one thing that surprised me. Some of the adjustments in JRA55-do were made I think to reduce drift, and so I was expected larger drifts with ERA-5 without these adjustments. But the magnitude of the drift isn’t really any larger. Likewise, the consistency between the circulation metrics is also remarkable. The resolution has a much bigger impact. I guess its saying that the bulk wind stresses between the two forcing products are consistent, and model physics is important. I’m hoping @willrhobbs will do a more detailed analysis of sea ice. I’m not sure I know enough to offer any interpretations. However, it is interesting to see that `025deg_era5_iaf` run does capture some of this year’s very low Antarctic sea ice, although it may not be as extreme as in observations. Re: RYF circulation metrics. Unfortunately I think I deleted the `ty_trans_rho` diagnostics from these (I think to save space in e14, it was a while ago). However, there are a few metrics plotted in this old notebook - [https://github.com/rmholmes/cosima-scripts/blob/master/ERA-5/ERA-5\_Initial\_Analysis-RYF-old\_more\_vars\_equatorial.ipynb](https://github.com/rmholmes/cosima-scripts/blob/master/ERA-5/ERA-5_Initial_Analysis-RYF-old_more_vars_equatorial.ipynb). One last thing: The original reason I was interested in these simulations was to see if they improved on JRA-55’s really weak tropical instability wave activity in the equatorial Pacific. There are suggestions from some papers that the very weak North Equatorial Counter Current in OMIP-2 forced simulations is because of some of the adjustments made to integrate scatterometry data in JRA55-do (but not in ERA-5). However, in the RYF 1/4-degree simulations TIWs are only slightly stronger in ERA-5, and still way too weak (see last plots in [https://github.com/rmholmes/cosima-scripts/blob/master/ERA-5/ERA-5\_Initial\_Analysis-RYF-old\_more\_vars\_equatorial.ipynb](https://github.com/rmholmes/cosima-scripts/blob/master/ERA-5/ERA-5_Initial_Analysis-RYF-old_more_vars_equatorial.ipynb)). I need to revisit this in the IAF simulations. ---
**Author:** ![willrhobbs](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/willrhobbs/32/208_2.png) [@willrhobbs](https://forum.access-hive.org.au/u/willrhobbs)\ **Post date:** [21 August 2023 07:19 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/5 "2023-08-21T07:19:10Z")
@Aidan I’m bringing a poster on (Antarctic) sea ice comparison to the COSIMA workshop between ERA5, the IAF and obs (1/4 degree model). Not sure how far I’ll get with it, but ideally I’ll get as far as the dynamic/thermodynamic tendency terms,. ---
**Author:** ![rmholmes](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/rmholmes/32/117_2.png) [@rmholmes](https://forum.access-hive.org.au/u/rmholmes)\ **Post date:** [14 April 2024 22:24 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/6 "2024-04-14T22:24:06Z")
For anyone who is using recent data from the `access-om2-025/025deg_era5_iaf` run, please note that I have just extended this run to the end of 2023. Note that 2023 is now `output043` and run as one contiguous year, replacing the previous `output043-045` which were irregular runs of just a few months. I have also extended the `access-om2-025/025deg_jra55_iaf_era5comparison` run to the end of 2023 (this is the run that is an apples-to-apples comparison to `025deg_era5_iaf`). @micael can you please trigger an update of the cookbook database to take into account these changes? @willrhobbs , @aekiss ---
**Author:** ![willrhobbs](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/willrhobbs/32/208_2.png) [@willrhobbs](https://forum.access-hive.org.au/u/willrhobbs)\ **Post date:** [14 April 2024 23:31 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/7 "2024-04-14T23:31:44Z")
Thanks Ryan, that’s great! ---
**Author:** ![micael](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/micael/32/93_2.png) [@micael](https://forum.access-hive.org.au/u/micael)\ **Post date:** [15 April 2024 00:34 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/8 "2024-04-15T00:34:01Z")
> [@rmholmes](#): > > @micael can you please trigger an update of the cookbook database to take into account these changes? It’s running now. Should take a few hours. ---
**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:** [15 April 2024 02:08 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/9 "2024-04-15T02:08:02Z")
> [@willrhobbs](#): > > I’m bringing a poster on (Antarctic) sea ice comparison to the COSIMA workshop between ERA5, the IAF and obs (1/4 degree model) Hi @willrhobbs. If this poster isn’t on the hive anywhere feel free to upload a PDR or PNG of the poster in this topic. Or in a separate topic and link to it. ---
**Author:** ![willrhobbs](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/willrhobbs/32/208_2.png) [@willrhobbs](https://forum.access-hive.org.au/u/willrhobbs)\ **Post date:** [15 April 2024 06:09 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/10 "2024-04-15T06:09:06Z")
@Aidan Here it is - the timeplot of sea ice anomalies is probably most relevant, although the maps show that the model had too much ice almost everywhere last winter [COSIMA\_2023\_poster.pdf](https://forum.access-hive.org.au/uploads/short-url/5VDI5KK0dw17noI4L8J7cshKz73.pdf) (2.1 MB) ---
**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:** [15 April 2024 06:26 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/11 "2024-04-15T06:26:37Z")
That is very nice! Tah. Hope you don’t mind, I’ve uploaded a PNG so it can be seen inline. ![COSIMA_2023_poster](https://us1.discourse-cdn.com/flex020/uploads/access1/original/2X/a/adaf46678fe4f4374255c3420f87b1c5f72ca327.jpeg) ---
**Author:** ![rmholmes](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/rmholmes/32/117_2.png) [@rmholmes](https://forum.access-hive.org.au/u/rmholmes)\ **Post date:** [24 March 2025 03:05 UTC](https://forum.access-hive.org.au/t/era-5-forced-access-om2-simulations/1103/12 "2025-03-24T03:05:49Z")
Please note that I have added another simulation to this set; a second 1/4-degree IAF simulation that has a longer spin up (starting in 1958 rather than 1980) and more extensive diagnostics. This is in the ik11 outputs under `access-om2-025/025deg_era5_iaf_1958cycle1`, details added to the post above. For now I’m going to keep the shorter spin-up (`025deg_era5_iaf`) as some others are using it. But it’s a potential candidate for deletion if space becomes an issue.