# Change forcing from PD to piControl in CM2

**URL:** <https://forum.access-hive.org.au/t/change-forcing-from-pd-to-picontrol-in-cm2/4664>\
**Category:** Earth System\
**Tags:** help, access-cm2\
**Created:** [2 July 2025 03:52 UTC](https://forum.access-hive.org.au/t/change-forcing-from-pd-to-picontrol-in-cm2/4664 "2025-07-02T03:52:31Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![wghuneke](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/wghuneke/32/102_2.png) [@wghuneke](https://forum.access-hive.org.au/u/wghuneke)\
**Post date:** [2 July 2025 03:52 UTC](https://forum.access-hive.org.au/t/change-forcing-from-pd-to-picontrol-in-cm2/4664/1 "2025-07-02T03:52:31Z")

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Hello,

How do I change a CM2 suite from present day to pre-industrial?

Thanks,  
Wilma

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**Author:** ![anton](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/anton/32/1836_2.png) [@anton](https://forum.access-hive.org.au/u/anton)\
**Post date:** [2 July 2025 04:29 UTC](https://forum.access-hive.org.au/t/change-forcing-from-pd-to-picontrol-in-cm2/4664/2 "2025-07-02T04:29:11Z")

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Hi Wilma

Whats the goal here - can you just start with a PI configuration (e.g. cy339)?

I guess you want to use the spun-up ocean from a PD experiment for a PI control experiment ?

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**Author:** ![wghuneke](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/wghuneke/32/102_2.png) [@wghuneke](https://forum.access-hive.org.au/u/wghuneke)\
**Post date:** [2 July 2025 04:32 UTC](https://forum.access-hive.org.au/t/change-forcing-from-pd-to-picontrol-in-cm2/4664/3 "2025-07-02T04:32:26Z")

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Hi, I’m using the CM2-025 configuration which is PD and now want to do a piControl run, if that helps.

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**Author:** ![spencerwong](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/spencerwong/32/1894_2.png) [@spencerwong](https://forum.access-hive.org.au/u/spencerwong)\
**Post date:** [3 July 2025 00:16 UTC](https://forum.access-hive.org.au/t/change-forcing-from-pd-to-picontrol-in-cm2/4664/4 "2025-07-03T00:16:25Z")

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Hi @wghuneke, I’ll try and take a look into which changes will need to be made. Is your PD CM2-025 configuration available to checkout from [mosrs](https://code.metoffice.gov.uk/trac/roses-u/browser/)?

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**Author:** ![spencerwong](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/spencerwong/32/1894_2.png) [@spencerwong](https://forum.access-hive.org.au/u/spencerwong)\
**Post date:** [4 July 2025 02:26 UTC](https://forum.access-hive.org.au/t/change-forcing-from-pd-to-picontrol-in-cm2/4664/5 "2025-07-04T02:26:51Z")

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Hi @wghuneke, @MartinDix has shared [this comparison](https://code.metoffice.gov.uk/trac/roses-u/changeset?reponame=&new=178649%40b%2Fz%2F6%2F8%2F7%2Ftrunk&old=174635%40b%2Fr%2F5%2F6%2F5%2Ftrunk#file1) between the 1 degree PI and 1 degree PD suites (mosrs login required).

You should be able to apply the opposite changes to swap to the pre-industrial forcings. Specifically the changes to the spectral files, gas MMRs, and ozone and emissions ancillaries. The changes to the `suite.rc` were related to cleaning up the suite, and shouldn’t need to be reversed.

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**Author:** ![spencerwong](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/spencerwong/32/1894_2.png) [@spencerwong](https://forum.access-hive.org.au/u/spencerwong)\
**Post date:** [14 July 2025 06:30 UTC](https://forum.access-hive.org.au/t/change-forcing-from-pd-to-picontrol-in-cm2/4664/6 "2025-07-14T06:30:31Z")

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