Recent ancil files for UM-UKCA

Unified Model
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Hello, I’ll be running nudged UM-UKCA simulations from 2018 to 2024 on Monsoon2. My current ancil files are (mostly) climatologies for ~2010, but I would like something closer to present day. I’m particularly interested in updating the sea ice content as I’m focusing on dust transport to the Arctic.

I’ve had a look around my current ancil directory (ukca-admin) and can see some 2014 timeslices. Do you know of any more recent ancils available on Monsoon2?

Thanks, Ross

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Dear Ross,

We’d recommend using UKESM1 or UKESM1.1 for science configurations, as these are well tested and documented. It is possible to nudge these configurations, although this can be a bit fiddly and some fixes may need to be applied depending on the UM version used. These instructions here show how to do this for UMvn11.1 UKESM1-AMIP configurations

https://www.ukca.ac.uk/wiki/index.php/Nudged_UKESM1-AMIP

At later UM versions it’s possible to do this slightly differently, and I have some configurations at UM13.x UKESM1.1.

In terms of ancillary files, could you use those produced for CMIP6

/projects/ancils/cmip6/ancils/n96e

These go up to 2014 for the historical time series, but then there are the ScienarioMIP files that go from 2015 to 2100. For instance, AerChemMIP ran SSP3-7.0 as part of its protocol, and I’ve done this with our nudged ACSIS simulations. You’d need to look into the scenarios to see which one suits you best, but generally they are pretty similar for the first few years of the scenarios. It’s these ancillaries that we use for all our future runs.

Many thanks and best wishes,
Luke

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Thanks for the reply Luke,

I’m using a suite that uses GLOMAP dust instead of CLASSIC dust (Jones et al 2022 ACP - Below-cloud scavenging of aerosol by rain: a review of numerical modelling approaches and sensitivity simulations with mineral dust in the Met Office's Unified Model), with the inclusion of a super-coarse dust mode. So it is not possible to switch to using one of the UKESM science configurations. I have configured it to run on a gregorian calendar and nudged to ERA5.

I think the CMIP6 projections will be okay for the UKCA ancillaries so thank you for the information. What do you suggest for SST/SIC? I will be directly comparing against ambient measurements made across several years and locations so would prefer a climatology rather than projections.

Thanks, Ross

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Mohit Dalvi has made up Reynold’s SSTs and Sea-Ice fields for use with nuding. The most recent of these can be found in my directory here:

/projects/ukca-cam/hadlk/ancil/sstsice

They only go up to May 2022 though. I’ll email Mohit to check if there are any more recent ones.

Best wishes,
Luke

1 Like
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ah that’s perfect, thank you!
Ross

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Dear Ross,

Mohit has updated the Reynold’s datasets and has placed them here:

/projects/ukca-admin/inputs/ancil/gregorian/n96e/reynolds/v2.1

Please note the date ranges of the various files:

reynolds_seaice_198109-202205.anc
reynolds_seaice_201401-202312.anc
reynolds_sst_198109-202205.anc
reynolds_sst_201401-202312.anc

You may need to update the SST and sea-ice files used when you also update to the ScenarioMIP ancillary files.

Many thanks to Mohit for making these up.

Best wishes,
Luke

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Thank you both, that’s excellent.

Ross

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