Ozone#
Key contacts#
- Names: Michaela Hegglin
- Emails: m.i.hegglin@fz-juelich.de
Summary#
Ozone forcing for the pre-industrial control and historical (and associated) simulations is available.
As a result of an issue being found (#400),
models that rely on exogenous ozone forcing are required to use different versions of the ozone files
for pre-industrial control (and related) simulations and historical (and related) simulations.
For all historical (and related) simulations, files with the source ID FZJ-CMIP-ozone-2-0 should be used.
For pre-industrial control (and related) simulations, files with the source ID FZJ-CMIP-ozone-1-2 should be used
(note that this guidance differs from the email communication sent by the CMIP IPO on 12 February 2026).
For details of your options for pre-industrial control simulations,
please see Recommendation for pre-industrial control.
The CMIP Panel co-chairs are recommending that,
for modelling centres who rely on ozone as an external forcing,
historical, and other relevant DECK (e.g., AMIP), simulations
should be re-run with the FZJ-CMIP-ozone-2-0 ozone if possible.
(Pre-industrial control simulations do not need to be re-run
because they are unaffected by the release of FZJ-CMIP-ozone-2-0.)
If any modelling centres cannot re-run their historical simulations, they should contact the ozone forcing providers for guidance on how to ensure a smooth connection between the scenario ozone forcing files.
If any modelling centres run historical simulations
with both the FZJ-CMIP-ozone-1-2 and FZJ-CMIP-ozone-2-0 forcing,
these simulations would be of interest to the Forcings Task Team.
Source IDs for CMIP7 phases#
The source ID that identifies the dataset to use in CMIP7 is given below.
DECK#
CMIP7#
For the DECK simulations in the production phase of CMIP7, you will need data from the following source IDs:
Retrieving and only using valid data will require some care. Please make sure you read the guidance given at the start of the Summary section and process the data carefully.
The data has the DOI: 10.25981/ESGF.input4MIPs.CMIP7/2584173.
This data is for use in CMIP7 production simulations.
All data sets for use in CMIP7 production simulations are published with a mip_era metadata value of 'CMIP7'.
This metadata value appears both in the file's global metadata as well as its metadata on ESGF.
If you find an issue, please create an issue on GitHub so that the identification and resolution of this issue is publicly accessible.
Testing#
No data available for this phase yet.
ScenarioMIP#
CMIP7#
No data available for this phase yet.
Testing#
No data available for this phase yet.
Navigating the data#
Recommendation for pre-industrial control#
The piControl forcing should come from files with the source ID FZJ-CMIP-ozone-1-2 data,
(there are no specific piControl files available in the FZJ-CMIP-ozone-2-0 data).
Note that this guidance differs from the email communication sent by the CMIP IPO on 12 February 2026.
For pre-industrial control, there are two options.
The first is the monthly climatology file (frequency value of monC).
This dataset averages over a longer simulation, essentially removing variability like the QBO.
If you wish to use this forcing for your piControl,
simply apply it on repeat.
The second is a transient file which has a time range equal to 182901-184912 in the filename.
This file is found in the same directory as files for the time range after 1850
so please be careful to only use it for piControl and do not include for other simulations.
This transient piControl forcing includes the QBO signal
but uses average solar forcing and repeating 1850 emissions.
If you wish to use this forcing for your piControl,
simply apply it on repeat.
Data#
At present, only a historical forcing which includes the QBO signal is provided. If you would like a historical forcing without the QBO signal, please comment on this discussion, specifically this thread.
There are also zmta (temperature) files available.
These provide the temperature output that is consistent with the provided ozone files.
This may be useful for those wishing to post-process the ozone forcings into other forms
(e.g. https://github.com/PCMDI/input4MIPs_CVs/discussions/378).
Differences in format from CMIP6 or other previous versions#
The data format is currently very similar, if not the same as CMIP6 (e.g. variable names are the same, dimensions are the same). The only change is that we have cleaned up the format to make it as close to being CF-compliant as possible (although it is not fully compliant because of a bounds issue for latitudes, please raise an issue if these bounds errors are an insurmountable problem).
Revision history#
FZJ-CMIP-ozone-1-2#
A member of the community raised an issue with a discontinuity between the piControl climatology and the historical ozone in this version. The full discussion is at https://github.com/PCMDI/input4MIPs_CVs/issues/400. FZJ-CMIP-ozone-2-0 fixes the underlying issue for the historical period only. For piControl, please continue to use the FZJ-CMIP-ozone-1-2 files (note that this guidance differs from the email communication sent by the CMIP IPO on 12 February 2026).
FZJ-CMIP-ozone-1-1#
A spurious large value was found in the climatology data related to this dataset, see here. In addition, the latitudinal bounds in this file were not correct. Both of these issues are corrected in FZJ-CMIP-ozone-1-2.
FZJ-CMIP-ozone-1-0#
The fill value attribute was missing in these files. They were hence retracted (although, if you're very careful, they are still usable, you just have to set the fill value manually). The original issue that identified this is here