DMS in AM3 - update ancillary file

Atmosphere AM3
1

Hi AM3 team, (and @Matt_Woodhouse, @BecJackson @alanah.chapman @ZhangchengPei )

I’ve just been poking around the AM3 ancillary files.

It looks like AM3 (N96 with interactive aerosol) is using the Lana et al. DMS climatology. This climatology is the standard, though a new one was released a few years ago now and my testing showed that it did make a bit of a difference to the cloud/radiation bias over the SO in AM2, and that some of the negative impacts that it produced were moderated by turning on the PMO aerosols (they are already on for AM3). In addition to my own paper ( ACP - The ACCESS-AM2 climate model underestimates aerosol concentration in the Southern Ocean; improving aerosol representation could be problematic for the global energy balance ) there is a bit of othr literature around showing that this update performs well.

Anyway, I’m wondering what a pathway could be to test/get the new DMS climatology (Hulswar) into AM3? I’ve got the 1x1 deg file - which I have regridded to the n96 grid, but perhaps the NRI team can do a better job at regridding than I did… :slight_smile:

I’m happy to run a few tests, or is it better of this is done in house?

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ALLLSO - I’ve found similar improvments when I updated the chlorophyll fields to something realistic that @dougiesquire sent me. But that was in rAM3 not AM3 - so hasn’t been tested for global impact. But perhaps something that could be done simultaneously?

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Hi Sonya,

We have the CCI-Ancillary-Suite which has been used to create ancillaries for experimental AM3 runs e.g. W21C’s n512e runs. You wouldn’t need to run the whole suite, but take a look at the ancil_clim_dms task- that’s the method used to create the DMS ancils for AM3 thus far. Should be able to take the python script there and use it with your DMS file and the existing AM3 landmask.

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To add to what @lachlanswhyborn said, for the moment, the n96 suite is using CMIP6 ancillaries. We will be updating to CMIP7 ancillaries in the coming months but we are also interested to hear from the community on the datasets they are interested to use.

@sonyafiddes , if you don’t mind doing some tests using the python script Lachlan mentioned that would be great. I’ve opened issues about the DMS data source and the chlorophyll fields.

Just to make sure, is the chlorophyll ancillary file the same as the sea colour?