UKCA Chemistry and Aerosol UMvn13.0 Tutorial 2

UKCA Chemistry and Aerosol Tutorials at UMvn13.0

Difficulty	EASY
Time to Complete	Under 1 hour
Video instructions

Remember to run mosrs-cache-password in your Rose suite and UM branch terminals.

Changing UKCA Box Model Options

This tutorial describes how to change the time settings, meteorological conditions, tracer initialisations, chemistry, and aerosol options in the UKCA Box Model.

Changing the Box Model Time Settings

The time settings for the box model can be found in the ukca $\rightarrow$ namelist $\rightarrow$ Time Settings panel and the ukca $\rightarrow$ namelist $\rightarrow$ Science Settings $\rightarrow$ Chemistry panel. The key variables are:

Panel	Variable	Description	Example
Time Settings	model_basis_time	The nominal start time of the model, defined as YEAR, MONTH, DAY, HOUR, MINUTE, SECOND	1989,09,01,00,00,00 (i.e. midnight on 1st September 1989)
Time Settings	run_target_end	The run length of model, defined as YEARS, MONTHS, DAYS, HOURS, MINUTES, SECONDS	0,0,1,0,0,0 (i.e. 1 day)
Time Settings	steps_per_periodim	The number of "dynamical" timesteps per "period" (a model day, containing the number of seconds given in the secs_per_periodim variable above)	24 (i.e. 1 hour)
Chemistry	chem_timestep	The number of seconds in a chemical timestep. This must be a multiple of the value of steps_per_periodim	3600 (i.e. 1 hour)

Task 2.1: Change the Start Time

O3 mass-mixing ratio when started from midday.

TASK 2.1: Change the start time of the model to begin at midday rather than midnight.

Solution
Change the value of model_basis_time to be 1989,09,01,12,00,00

Once the run has finished, replot ozone and see how the graph has changed.

Worked Solution to Task 2.1

The changes to Rose are:

• https://code.metoffice.gov.uk/trac/roses-u/changeset/236400/c/q/7/8/2/trunk

Index: app/ukca/rose-app.conf
===================================================================
--- app/ukca/rose-app.conf	(revision 236285)
+++ app/ukca/rose-app.conf	(revision 236400)
@@ -145,7 +145,7 @@
 ltimer=.true.
 !!ltimers_user=.false.
 model_analysis_mins=0
-model_basis_time=1981,09,01,00,00,00
+model_basis_time=1981,09,01,12,00,00
 num_albcs=0
 run_target_end=0,0,1,0,0,0

These differences can be found here:

Tutorials/UMvn13.0/worked_solutions/Task02.1/Task02.1_rose.patch

Task 2.2: Increase the run-length

O3 mass-mixing ratio for a 5-day run.

TASK 2.2: Increase the run length of the box model to 5 days.

Solution
Change the value of run_target_end to be 0,0,5,0,0,0

Once the run has finished, replot ozone and see how the graph has changed.

Worked Solution to Task 2.2

The changes to Rose are:

• https://code.metoffice.gov.uk/trac/roses-u/changeset/236409/c/q/7/8/2/trunk

Index: app/ukca/rose-app.conf
===================================================================
--- app/ukca/rose-app.conf	(revision 236400)
+++ app/ukca/rose-app.conf	(revision 236409)
@@ -147,7 +147,7 @@
 model_analysis_mins=0
 model_basis_time=1981,09,01,12,00,00
 num_albcs=0
-run_target_end=0,0,1,0,0,0
+run_target_end=0,0,5,0,0,0
 
 [namelist:nlstcall_box_options]
 flux_out_filename='flux_out.csv'

These differences can be found here:

Tutorials/UMvn13.0/worked_solutions/Task02.2/Task02.2_rose.patch

Task 2.3: Increase the run-length

O3 mass-mixing ratio for a 5-day run with a 30-minute timestep.

TASK 2.3: Change the timestep to be 30 minutes.

Solution
Change the value of steps_per_periodim to be 48 and chem_timestep to be 1800.

Once the run has finished, replot ozone and see how the graph has changed.

Worked Solution to Task 2.3

The changes to Rose are:

• https://code.metoffice.gov.uk/trac/roses-u/changeset/236413/c/q/7/8/2/trunk

Index: app/ukca/rose-app.conf
===================================================================
--- app/ukca/rose-app.conf	(revision 236409)
+++ app/ukca/rose-app.conf	(revision 236413)
@@ -178,7 +178,7 @@
 !!ppxm=1
 !!psum_filename_base='$DATAM/${RUNID}a_s'
 secs_per_periodim=86400
-steps_per_periodim=24
+steps_per_periodim=48
 
 [!!namelist:oasis_send_nml]
 !!hybrid_rmp_mapping='BILINEAR'
@@ -467,7 +467,7 @@
 
 [namelist:run_ukca]
 !!biom_aer_ems_scaling=2.0
-chem_timestep=3600
+chem_timestep=1800
 !!dir_strat_aer=
 !!dts0=300
 fastjx_mode=1

These differences can be found here:

Tutorials/UMvn13.0/worked_solutions/Task02.3/Task02.3_rose.patch

Changing the Box Model Environmental Settings

The environmental conditions used by the box model are set by the variable ukca_box_nml in the ukca $\rightarrow$ namelist $\rightarrow$ Model Input and Output panel. The value corresponds to a Fortran namelist file held in the

[SUITE-ID]/app/ukca/file

directory. Currently 3 example files are provided:

File	Description
nml_box_sfc	A box with settings relevant for surface conditions
nml_box_tropopause	A box with settings relevant for conditions around the tropopause
nml_box_strat	A box with settings relevant for conditions in the stratosphere

You can make your own file and place it in the same directory, although remember to

fcm add nml_box_[YOUR FILE]

otherwise you will not be able to commit the file to the suite repository.

Example file: nml_box_sfc

!-----------------------------------------------
! Box-MODEL test NAMELIST - surface
!-----------------------------------------------

! Section to define environmental parameters for box model
&ENVIRONMENT_PARS
  latitude_1       = 30.     ! Latitude, degrees North, -90:90
  longitude_1      = 0.      ! Longitude, degrees East, 0:360
  t_theta_levels_1 = 288.15  ! Temperature, K
  p_theta_levels_1 = 100000. ! Pressure, Pa
  land_sea_mask_1  = .TRUE.  ! Land/sea mask, logical
  tstar_1          = 288.15  ! Tmperature at surface, K
  zbl_1            = 1000.   ! Height of boundary layer, m
  pstar_1          = 101325. ! Pressure at surface, Pa
  q_1              = 0.01    ! Mass fraction of water vapour in air
  qcf_1            = 0.0     ! Mass fraction of cloud ice in air
  qcl_1            = 0.0     ! Mass fraction of liquid cloud water in air
  surf_albedo_1    = 0.2     ! Surface albedo
/

! Section to define Offline Oxidant MMR values
! (only used if running with offline oxidants scheme)
&OFFLINE_OXIDANT_MMR
  O3             = 5.0000e-08
  OH             = 5.0000e-14
  HO2            = 5.0000e-12
  H2O2           = 5.0000e-10
  NO3            = 5.0000e-12
/

Task 2.4: Change the environmental conditions of the box

O3 mass-mixing ratio from a stratospheric box.

TASK 2.4: Change the environmental conditions to be in the stratosphere.

Solution
Change the value of ukca_box_nml to be nml_box_strat

Once the run has finished, replot ozone and see how the graph has changed.

Worked Solution to Task 2.4

The changes to Rose are:

• https://code.metoffice.gov.uk/trac/roses-u/changeset/236419/c/q/7/8/2/trunk

Index: app/ukca/rose-app.conf
===================================================================
--- app/ukca/rose-app.conf	(revision 236413)
+++ app/ukca/rose-app.conf	(revision 236419)
@@ -156,7 +156,7 @@
 tracer_in_filename='chem_tracer_pars_STwGMaero'
 tracer_nullval=1e-15
 tracer_out_filename='tracer_out.csv'
-ukca_box_nml='nml_box_sfc'
+ukca_box_nml='nml_box_strat'

 [namelist:nlstcgen]
 dump_filename_base='$DATAM/${RUNID}a.d%z%C'

These differences can be found here:

Tutorials/UMvn13.0/worked_solutions/Task02.4/Task02.4_rose.patch

Checklist

☐ List suites using rosie go

☐ Copy suites using the right-click menu

☐ Run suites using the play button

☐ Plot output using gnuplot

Tutorial 2

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Written by Luke Abraham 2022