Nudged UKESM1-AMIP

Nudged UKESM1-AMIP Configurations

Suite-ids: Met Office (u-bu342), Monsoon (u-br787), ARCHER ()

Met Office (u-bl917), Monsoon2 (u-bm242) and ARCHER (u-bm251) These suites contain an incorrect ancillary for Leaf Area Index, inherited from the 360-day AMIP release job.

Configuration Details/ Changes from 360-day version

Source: UKESM1 Atmosphere-only Release job: u-be303

The actual conversion of the UKESM1-AMIP release job (u-be303) to Gregorian calendar and turn on Nudging is fairly straight forward. However, the calculation and output of Monthly means in the setup (ap4,ap5,apm,apu streams) is governed by STASH Time Profile =TMONMN, which is hard-wired to average the fields every 30 days. This causes an increasing offset in the period over which the fields are averaged as the Gregorian run progresses. Depending on the length of the run, users may find (looking at the time-stamp on the data) that substantial data for the next' month is being used while calculating the current monthly means. In addition, the seasonal and annual means in UKESM1 suites are calculated offline, by the postproc task, although there do not appear to be any issues with this.

To address the monthly means issue, copies of the UKESM1-AMIP 360-day suite were converted to use Nudging, produce the correct monthly, (and seasonal, annual) means and ported to HPC systems as listed above

These suites use the UM-implicit climate meaning which is able to adjust the meaning period to the actual number of days in the current month. The seasonal and annual means continue to be created via the postprocessing task. The changes made are listed below for reference, but a few quick things to note while using the above suites:
- Any additional diagnostics required at monthly mean frequency have to be specified with profiles TDMPMN and UPMEAN only
- Following the base UKESM1-AMIP suite, the suites are set to run starting from 19790101. To change the start date and use your own initialisation file:

 - modify the rose-suite.conf file i.e. <Machine>_AINITIAL_DIR= and AINITIAL_FILE=
 - remove hardwiring of initial dump to 1979: Panel um-> namelist-> Reconf and Ancil Control-> output dump fixed headers: Select whether you need to overwrite the date in AINITIAL file (i_override_datatime) and specify the final date accordingly.

- The output files with < 1 month re-initialisation e.g. 10-days will still see an offset (e.g. timestamp of 12th or 22nd of the month), but this is unavoidable.
- The runs as set up seem to leave a lot of restart dumps lying around (and create one for 12th ,13th or 14th of each month !). In case the postproc task does not clear them out, it is recommended to regularly clear out older dumps e.g. those having date stamps up to 2 months prior to start of the current model cycle (but leave any January (YYYY0101_00) dumps for archiving) from <HPC>:~/cylc-run/<suite-id>/share/data/History_Data/.

Changes made to the UKESM1-AMIP Release job:
1. Switch to Gregorian calendar at the top level (rose-suite.conf EXPT_CALENDAR or Calendar in ‘Run Init and Cycling’ panel). This only affects the suite cycling formula and expected restart dump date stamps.
2. Switch to Gregorian calendar in the UM (Panel:Top level Model Control -> Run Control and Time settings: lcal360=False, l_climrealyr=True)
3. Use 365-day versions of a few NetCDF files: UKCA emissions for SO2_nat and CH4_biomass_low, EasyAerosol files (Machine specific paths in above suites). Other files/ ancillaries are expected to be calendar-independent.
4. Panel:Model Input and Output -> Dumping and meaning:

 a. Change Dumping frequency to ‘30’, ‘Days’ 
 b. greg_monthly_dump=True and end_of_run_dump = True
 c. l_meaning_sequence = True, ppselectim = 1,0,0,0
 d. mean_1_filename_base = $DATAM/${RUNID}a.pm%Y%b 
 e. Save and Close GUI and then edit app/um/rose-app.conf to manually activate (remove ‘!!’) and set [namelist:nlstcgen] meanfreqim=3,0,0,0
  This logical is deactivated by Rose but essential for Climate meaning. This will flagged up with 'red triangle' the next time the GUI is opened. 
  The value ‘3’ is arbitrary. In 360-day runs this refers to the number of restart dumping instances after which to do the meaning, but in 365-day runs this only has to be >1.
 f. Delete any app/um/opt/rose-app-gregorian.conf as this might overwrite the settings.

5. Panel: Model Input and Output -> Model Output Streams:

 a. Convert streams to use Real Months in Re-initialisation (reinit_unit) where applicable i.e. ’30 Days’ --> ‘1 Real Month’ , ’90 Days’ --> ‘3 Real Months’
 b. Deactivate the pp130 stream which is set up to create a .pm file. (via UPM usage profile)

6. Panel : Model Input and Output -> Stash Requests and Profiles -> Usage Profiles

  Create a UPMEAN profile with iocn = ‘Dump Store with Climate mean TAG’, macrotag = ‘15’

7. Panel : Model Input and Output -> Stash Requests and Profiles -> Stash Requests

  a. Modify all the monthly mean diagnostics to use TDMPMN and UPMEAN
  b. Turn Off all diagnostics which use UPM profile (as the target stream has been deactivated)
  c. Turn Off all TMONMN diagnostics as they are now inconsistent.
  d. (In the suites, all CMIP6-core diagnostics have been turned off as these are only relevant to runs specifically done under the CMIP6 project).

8. Panel:postproc -> Atmosphere -> File transformation or (app/postproc/rose-app.conf)

  Set create_monthly_means = True.

9. Top-level: suite.conf -> Tasks

  a. Turn Off ‘Run Development Tests’ as these (especially the NRUN-CRUN ones) are known to fail due to slight differences in  dumping frequency or mismatches in dump timestamps under Gregorian calendar.
  b. Turn Off ‘Archive integerity’ as this is also seen to fail, possibly due to differences between the expected and actual timestamps on the files to be processed.

10. Changes to use Nudging (Panel:um->namelist-> UM Science Settings -> Section 39: Nudging) are user-dependant, with example settings and m/c specific paths as specified in above suites.