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v12.0 Nested suite (CASIM or UKCA or both)

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dangrosvenor edited this page Mar 28, 2023 · 17 revisions

v12.0 Nested suite (CASIM or UKCA or both)

Paul Field set up a V12.0 nested suite for Sam Clarke (Erin Raif is using it too). Sam has tested it.

  • The normal process for creating ancillaries (fields that are prescribed and not calculated by the model) is to use high resolution datasets regridded to the region of the nest. This uses a program called ANTS. However, this doesn't work on Monsoon at the moment.

  • So, this suite uses the older program called CAPS, which should produce similar results to ANTS. However, this doesn't work for the soil ancillaries. And for polar/ice regions it doesn't work for the vegetation ancillaries.

  • So, for these we can downscale them from the driving global model fields - but note that we will then be starting with lower resolution fields than those used by ANTS or CAPS. If high resolution fields are required then one option is to make a copy of the suite just for creating ancillaries that uses N1280 resolution for the global model - this would then give a resolution of around 16km at the equator.

  • Suites created by Paul for copying :

    • u-cl357 - soil downscaled from global model - copy this one if outside of polar/ice-covered regions.
    • u-cl515 - veg and soil downscaled from global model - copy this one for polar/ice covered regions.

  • Copy these suites using e.g., :-

    • rosie copy u-cl357

  • These suites have a number of different configurations / experiments. The namelists (that control the various switches and settings) are located in e.g., rose-app-ra3_pack3.conf

    • ra3_p3_casim / ra3_pack3

      • Uses a constant in-cloud cloud droplet number concentration (CDNC; not UKCA aerosols to generate CDNC).
      • casim_iopt_act=0

    • ra3_p3_casim_arcl / expt1 - uses classic mass-only aerosol climatology rather than aerosols from the UKCA.

      • Uses the classic aerosol climatologies (these are mass only single moment aerosols) and converts to a number by assuming a mean sulphate particle size – this is then activated to give droplet number (over the UK we use the MURK scheme).

      • Uses casim_iopt_act=3

    • ra3_p3_casim_ukca / expt2

      • Uses UKCA aerosols to create droplets in CASIM via ARG (doesn't use the UKCA ACTIVATE scheme that takes into account the individual composition type of each aerosol but rather it passes the weighted mean effect of the different compositions into CASIM and uses that).
      • Uses casim_iopt_act=3
      • Plus a few other changes relative to the above.
      • Although l_ukca is not set here.
      • Paul says that :-
        • "Sorry – it gets overridden – I should change it. You can confirm by searching for l_ukca in the pe_output files in the work dir for the forecast job, e.g. :-
ACAO_km1p5_ra3_p3_casim_arcl_um_fcst_000/pe_output/umnsa.fort6.pe000:l_ukca = T
ACAO_km1p5_ra3_p3_casim_ukca_um_fcst_000/pe_output/umnsa.fort6.pe000:l_ukca = T
ACAO_km1p5_ra3_p3_casim_um_fcst_000/pe_output/umnsa.fort6.pe000:l_ukca = T" ```

    * And that it is set as true for all configurations.
    * This is done (he thinks) in the suite-macros.rc file at the top level of your suite:-
      * "USE_UKCA set to true causes the suite-macros.rc to set all the l_ukca etc to true"

  * Some other info about all of these suites :-
    * They use the bimodal cloud fraction scheme.
    * Set up to archive to crum.
    * Aerosol processing (where aerosol number is reduced by droplet coalescence, etc. if followed by cloud evaporation) is possible, but need to set up an experiment/namelist. Maybe a new branch too.
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