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 shape of the graph has changed.

Task 2.2: Increase the run-length

O3 mass-mixing ratio when started from midday.

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

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 shape of 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

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

Written by Luke Abraham 2022