UKCA Chemistry and Aerosol UMvn13.9 Tutorial 6

UKCA Chemistry and Aerosol Tutorials at UMvn13.9

Difficulty	HARD
Time to Complete	2 or more hours
Video instructions	Walkthrough (YouTube)

Remember to run mosrs-cache-password.

What you will learn in this Tutorial

In this tutorial you will learn how to output and process aerosol diagnostics from UKCA.

Python

In this Tutorial you will make extensive use of Python to process the UM output. Instructions as to how to use this are in Tutorial 5.

Example python scripts are provided for each Task, and you should take the time to read through these and understand what they are doing. None of these scripts plot any of the output, so as an extension to these tasks you could try extending the scripts to plot the output from python directly, rather than visualising via Xconv. Further information (and examples) on how Iris plots can be found here:

• https://scitools-iris.readthedocs.io/en/latest/userguide/plotting_a_cube.html
• https://scitools-iris.readthedocs.io/en/latest/generated/gallery/general/plot_global_map.html

Task 6.1: Output aerosol diagnostics

TASK 6.1: Output the following aerosol and radiation diagnostics to a new UPL output stream that reinitialises every 3 hours. You should make a new time profile (called TRAD) to only output these on radiation timesteps. You will also need to make a new domain profile (called D3DAR) for s02i530 and s02i540, to output these on both model levels and pseudo levels.

Hint
Incoming and outgoing radiation are single-level fields that should be output using the DIAG profile.
Remember to output your aerosol diagnostics on the AOT pseudo levels using the DIAGAOT profile.

STASH Section	STASH Item	STASH Name
1	207	INCOMING SW RAD FLUX (TOA): ALL TSS
1	208	OUTGOING SW RAD FLUX (TOA)
2	205	OUTGOING LW RAD FLUX (TOA)
2	285	MINERAL DUST OPTICAL DEPTH IN RADN.
2	300	AITKEN MODE (SOLUBLE) OPTICAL DEPTH
2	301	ACCUM MODE (SOLUBLE) OPTICAL DEPTH
2	302	COARSE MODE (SOLUBLE) OPTICAL DEPTH
2	303	AITKEN MODE (INSOL) OPTICAL DEPTH
2	304	ACCUM MODE (INSOL) OPTICAL DEPTH
2	305	COARSE MODE (INSOL) OPTICAL DEPTH
2	585	MINERAL DUST ABS. OPICAL DEPTH
2	240	AITKEN (SOLUBLE) ABS OPTICAL DEPTH
2	241	ACCUM (SOLUBLE) ABS OPTICAL DEPTH
2	242	COARSE (SOLUBLE) ABS OPTICAL DEPTH
2	243	AITKEN (INSOL) ABS OPTICAL DEPTH
2	244	ACCUM (INSOL) ABS OPTICAL DEPTH
2	245	COARSE (INSOL) ABS OPTICAL DEPTH
2	530	UKCA 3D AEROSOL EXTINCTION
2	540	CLASSIC 3D AEROSOL EXTINCTION

Radiation Timesteps

The number of shortwave radiation timesteps per day is given by i_sw_radstep_perday_prog, found in um $\rightarrow$ namelist $\rightarrow$ UM Science Settings $\rightarrow$ Section 01 - 02 Radiation $\rightarrow$ Shortwave. The equivalent for longwave is i_lw_radstep_perday_prog, found in um $\rightarrow$ namelist $\rightarrow$ UM Science Settings $\rightarrow$ Section 01 - 02 Radiation $\rightarrow$ Longwave.

In the UKCA training suite, both of these are set to 16, i.e. a call every 90 minutes. This value is very configuration dependent - sometimes radiation is called every hour (24), sometimes every 3 hours (8) etc. You should check the settings in your suite if you need to consider any of the radiation diagnostics.

Making new STASH profiles

While we have covered outputting and analysing diagnostics in Tutorial 4 and Tutorial 5 you were only making use of existing settings for the different "profiles" that define how the diagnostics are considered in space and time.

Here you will learn how to make new time, domain, and usage profiles.

Time profiles

The new time panel in Rose.

To make a new time profile, go to: um $\rightarrow$ namelist $\rightarrow$ Model Input and Output $\rightarrow$ STASH Requests and Profiles $\rightarrow$ Time Profiles. This contains a list of existing time profiles, with names like t3hmn_039ecafe etc.

To make a new time profile, you should:

1. Right-click anywhere on the list and click the green plus symbol (+) named Add new section

   This will make a new blank line (usually labelled 1, the next 2 etc.) with a red X next to it.

2. Right-click this new line and click View namelist.
3. Fill-in the values as required for what you want to do.
4. When you have finished, you will need to run the When you have finished, you will need to run the stashindices.TidyStashTransform macro by going to the Metadata $\rightarrow$ um drop-down menu. This will rename the new profile into the correct format.

Example: Output on Radiation Timesteps

You will have discovered that there are 16 radiation timesteps per day, but to work out how to output diagnostics you need to know many model timesteps per day there are. This can be found at: um $\rightarrow$ namelist $\rightarrow$ Top Level Model Control $\rightarrow$ Model Domain and Timestep. The number is given by the variable steps_per_periodim, which is defined as the number of steps per period given (in seconds) by secs_per_periodim. For one day, this value is 86400 (24h x 60m x 60s).

In the UKCA training suite, secs_per_periodim=86400, and steps_per_periodim=48. This means that there are 48 timesteps per day, i.e. each timestep is 30 minutes.

We can combine this with the number of radiation timesteps per day (16), to calculate that radiation is called every third model timestep (48/16 = 3) in this configuration. We can now fill-in the values in the new time profile accordingly, e.g.

• ityp: No time processing
• tim_name: e.g. TRAD
• unt3: Timesteps (1)
• iopt: Regular intervals
• istr: 1 (i.e. start on first timestep)
• iend: -1 (i.e. never stop outputting)
• ifre: 3 (i.e. output every third timestep)

We need to start at timestep 1, as radiation is called on the first timestep, and then called every third model timestep after that. In contrast, the UKCA Newton-Raphson chemical solver is first called on the first hour, and then every hour after that. For the UKCA training suite this would mean that istr=2 and ifre=2, but for standard UKCA runs at N96eL85 with a 20-minute timestep this would have istr=3 and ifre=3.

Domain profiles

The new domain panel in Rose.

To make a new domain profile, go to: um $\rightarrow$ namelist $\rightarrow$ Model Input and Output $\rightarrow$ STASH Requests and Profiles $\rightarrow$ Domain Profiles. This contains a list of existing domain profiles, with names like dallth_1e2e730d etc.

To make a new domain profile, you should:

1. Right-click anywhere on the list and click the green plus symbol (+) named Add new section

   This will make a new blank line (usually labelled 1, the next 2 etc.) with a red X next to it.

2. Right-click this new line and click View namelist.
3. Fill-in the values as required for what you want to do.
4. When you have finished, you will need to run the When you have finished, you will need to run the stashindices.TidyStashTransform macro by going to the Metadata $\rightarrow$ um drop-down menu. This will rename the new profile into the correct format.

Example: Output AOT pseudo levels on all model theta levels

Aerosol diagnostics are defined on a series of 6 pseudo levels, corresponding to 0.38, 0.44, 0.55, 0.67, 0.87, and 1.02 microns. You will therefore need to output on your data on all of these. For some diagnostics, such as AOD, these are defined on a single level, but others, such as extinction, are a 3D field over the whole atmosphere. Therefore, to output the 3D aerosol extinction we need to make a new profile over all model (theta grid) levels, and all 6 pseudo levels.

We can now fill-in the values in the new domain profile accordingly, e.g.

• dom_name: e.g. D3DAR
• iopl: Variable derived on model theta levels (Charney-Phillips Grid) (2)
• ilevs: provide range [bottom and top level numbers]
• ilevb: 1 (i.e. 20m level)
• ilevt: 38 (i.e. highest level)
• plt: Radiation bands for calculating aerosol optical depth (4)

This will then insert a new option below (pslist) to allow you to specify the bands you require.

• pslist: press the green plus symbol (+) 5 times, and enter the numbers 1 to 6 in each of the boxes to output all AOT pseudo levels.
• iopa: Full model area (1)
• imsk: Land and sea points
• imn: None (0)
• iwt: None
• ts: false

Usage profiles

The new usage panel in Rose.

Making new usage profiles is not as straight-forward as for time and domain profiles, as these are used to output diagnostics to different output files (and possibly to climate mean files). To see what output streams are available, go to: um $\rightarrow$ namelist $\rightarrow$ Model Input and Output $\rightarrow$ Model Output Streams. In the UKCA training suite, only pp0 is active. As part of this tutorial you will need to make a new output stream.

For most modern UM jobs, climate meaning is off. However, to look at climate meaning, go to: um $\rightarrow$ namelist $\rightarrow$ Model Input and Output $\rightarrow$ Dumping and Meaning. This is controlled by the logical l_meaning_sequence, which in the UKCA training suite is set to false (i.e. no climate meaning). If this is set to true then various settings will need to be chosen, such as the reference time, the frequency of files, and which files to output.

To view the usage profiles, go to: um $\rightarrow$ namelist $\rightarrow$ Model Input and Output $\rightarrow$ STASH Requests and Profiles $\rightarrow$ Usage Profiles. This contains a list of existing domain profiles, with names like upa_ffb3f00b etc. If you look at the upa namelist (by right-clicking on it and clicking view namelist) you can see that this corresponds with the pp0 output stream. For this tutorial you will make a new usage profile and link it to your new output stream.

It is also possible to write diagnostics to a tag, which can then be read by other parts of the code. This is how UKCA couples to the UM, via tag=98. This can be seen in the upukca usage profile.

When you take a copy of an existing configuration it is unlikely that you will need to make any changes to any (or make new) usage profiles. However, if you do want to make a new usage profile, you should first make a new output stream:

1. Go to um $\rightarrow$ namelist $\rightarrow$ Model Input and Output $\rightarrow$ Model Output Streams and right-click anywhere on the list and click the green plus symbol (+) named Add new section.

   This will make a new blank line (usually labelled 1, the next 2 etc.) with a red X next to it.

2. Right-click this new line and click View namelist.
3. Fill-in the values as required for what you want to do.
4. When you have finished, you will need to rename this output stream via the right-hand menu by right-clicking on the entry.
5. Then go to um $\rightarrow$ namelist $\rightarrow$ Model Input and Output $\rightarrow$ STASH Requests and Profiles $\rightarrow$ Usage Profiles, right-click anywhere on the list and click the green plus symbol (+) named Add new section.

   This will make a new blank line (usually labelled 1, the next 2 etc.) with a red X next to it.

6. Right-click this new line and click View namelist.
7. Fill-in the values as required for what you want to do.
8. When you have finished, you will need to run the When you have finished, you will need to run the stashindices.TidyStashTransform macro by going to the Metadata $\rightarrow$ um drop-down menu. This will rename the new profile into the correct format.

Note that if you are making a new usage profile that is not associated with a tag, you may also need to make changes to the output streams. This could be quite involved.

Example: Make a new UPL usage profile and corresponding pp11 output stream

You will need to make the model output stream first, as described above and then fill in the values as below to make a stream and reinitialises every 3 hours, e.g.

• file_id: e.g. pp11
• filename: e.g. $ROSE_DATAC/$RUNID.pp11
• packing: (here we will use the same as UPA) 'New Climate' (5)
• reserved_headers: here we will set this to a large enough number, e.g. 16000. Sometimes you will get error messages telling you that "the number of fields exceeds reserved headers", and a solution to this is to increase this number further.
• l_reinit: True

This will then give you the following options for reinitialisation of the file. It will also remove the filename attribute which may not be needed but is best to provide.

• filename_base: e.g. $DATAM/${RUNID}a.pl%C
• reinit_unit: 'Hours' (4)
• reinit_start: 0 (i.e. start straight away)
• reinit_end: -1 (i.e. never stop)
• reinit_step: 3

This will just have a name of e.g. '1' at this point. To rename this to e.g. 'pp11' you will need to find it in the list on the right-hand panel under "Model Output Streams", right-click it, select "rename a section", and change the e.g.

namelist:nlstcall_pp(1)

to be

namelist:nlstcall_pp(pp11)

Now you need to make your new usage profile as described above, and fill in the values as below to use this new model output stream, e.g.

• use_name: e.g. UPL
• locn: To be written to a FF output stream with supplied file ID (3)

This will then give you the option below (file_id) to allow you to specify the output stream ID you defined above

• file_id: e.g. pp11 (as you defined above)

The run the TidyStashTransform macro to give this usage profile a correct name.

Using your new profiles

Once you have made your new profiles you should then use them in the usual way when outputting diagnostics, as covered in Tutorial 3.

When all your new STASH is set-up, you can use the Validator Macros to check if the names are correct, or if there are any unused STASH items etc. To run this, go to Metadata $\rightarrow$ Check all Validator Macros from the drop-down menu. You can also check for fail-if or warn-if issues. However, these won't warn of incorrect domain requests (i.e. requesting pressure-levels for diagnostics only defined on a single level), so some care should still be taken.

Solution to Task 6.1

You were given the task

• Output the following aerosol and radiation diagnostics to a new UPL output stream that reinitialises every 3 hours. You should make a new time profile (called TRAD) to only output these on radiation timesteps. You will also need to make a new domain profile (called D3DAR) for s02i530 and s02i540, to output these on both model levels and pseudo levels.

STASH Section	STASH Item	STASH Name
1	207	INCOMING SW RAD FLUX (TOA): ALL TSS
1	208	OUTGOING SW RAD FLUX (TOA)
2	205	OUTGOING LW RAD FLUX (TOA)
2	285	MINERAL DUST OPTICAL DEPTH IN RADN.
2	300	AITKEN MODE (SOLUBLE) OPTICAL DEPTH
2	301	ACCUM MODE (SOLUBLE) OPTICAL DEPTH
2	302	COARSE MODE (SOLUBLE) OPTICAL DEPTH
2	303	AITKEN MODE (INSOL) OPTICAL DEPTH
2	304	ACCUM MODE (INSOL) OPTICAL DEPTH
2	305	COARSE MODE (INSOL) OPTICAL DEPTH
2	585	MINERAL DUST ABS. OPICAL DEPTH
2	240	AITKEN (SOLUBLE) ABS OPTICAL DEPTH
2	241	ACCUM (SOLUBLE) ABS OPTICAL DEPTH
2	242	COARSE (SOLUBLE) ABS OPTICAL DEPTH
2	243	AITKEN (INSOL) ABS OPTICAL DEPTH
2	244	ACCUM (INSOL) ABS OPTICAL DEPTH
2	245	COARSE (INSOL) ABS OPTICAL DEPTH
2	530	UKCA 3D AEROSOL EXTINCTION
2	540	CLASSIC 3D AEROSOL EXTINCTION

and were given the hints

• Incoming and outgoing radiation are single-level fields that should be output using the DIAG profile.
• Remember to output your aerosol diagnostics on the AOT pseudo levels using the DIAGAOT profile.

The specific Rose changes made are:

• https://code.metoffice.gov.uk/trac/roses-u/changeset/337623/d/u/5/1/6/trunk

The specific Rose changes made are:

Index: app/um/rose-app.conf
===================================================================
--- app/um/rose-app.conf	(revision 337614)
+++ app/um/rose-app.conf	(revision 337623)
@@ -1679,6 +1679,18 @@
 reinit_unit=2
 reserved_headers=16000
 
+[namelist:nlstcall_pp(pp11)]
+file_id='pp11'
+!!filename='$ROSE_DATAC/$RUNID.pp11'
+filename_base='$DATAM/${RUNID}a.pl%C'
+l_reinit=.true.
+packing=5
+reinit_end=-1
+reinit_start=0
+reinit_step=3
+reinit_unit=1
+reserved_headers=16000
+
 [!namelist:nlstcall_pp(pp2)]
 file_id='pp2'
 !!filename='$ROSE_DATAC/$RUNID.pp2'
@@ -3423,6 +3435,40 @@
 ukca_mode_seg_size=4
 ussp_seg_size=32
 
+[namelist:umstash_domain(d3dar_17f7e88a)]
+dom_name='D3DAR'
+!!iest=0
+ilevs=1
+imn=0
+imsk=1
+!!inth=0
+iopa=1
+iopl=2
+!!isth=0
+!!iwst=0
+iwt=0
+!!l_spml_ts=.false.
+levb=1
+!!levlst=0
+levt=38
+plt=4
+pslist=1,2,3,4,5,6
+!!rlevlst=0
+!!spml_bot=0
+!!spml_ew=0
+!!spml_ns=0
+!!spml_top=0
+!!tblim=0
+!!tblimr=0
+!!telim=0
+!!tnlim=0
+ts=.false.
+!!tslim=0
+!!tsnum=0
+!!ttlim=0
+!!ttlimr=0
+!!twlim=0
+
 [namelist:umstash_domain(dallrh_0496a967)]
 dom_name='DALLRH'
 !!iest=0
@@ -3704,6 +3750,22 @@
 tim_name='TALLTS'
 use_name='UPUKCA'
 
+[namelist:umstash_streq(01207_a27dd756)]
+dom_name='DIAG'
+isec=1
+item=207
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(01208_3171c632)]
+dom_name='DIAG'
+isec=1
+item=208
+package=
+tim_name='TRAD'
+use_name='UPL'
+
 [namelist:umstash_streq(01235_3511dd9f)]
 dom_name='DIAG'
 isec=1
@@ -3712,6 +3774,78 @@
 tim_name='TALLTS'
 use_name='UPUKCA'
 
+[namelist:umstash_streq(02205_f31b05b3)]
+dom_name='DIAG'
+isec=2
+item=205
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02240_428b5acd)]
+dom_name='DIAGAOT'
+isec=2
+item=240
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02241_83ebc205)]
+dom_name='DIAGAOT'
+isec=2
+item=241
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02242_5a8d74dc)]
+dom_name='DIAGAOT'
+isec=2
+item=242
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02243_b109987d)]
+dom_name='DIAGAOT'
+isec=2
+item=243
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02244_4874edcf)]
+dom_name='DIAGAOT'
+isec=2
+item=244
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02245_87d0662f)]
+dom_name='DIAGAOT'
+isec=2
+item=245
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02285_8370d4a7)]
+dom_name='DIAGAOT'
+isec=2
+item=285
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02300_4fd94c8e)]
+dom_name='DIAGAOT'
+isec=2
+item=300
+package=
+tim_name='TRAD'
+use_name='UPL'
+
 [namelist:umstash_streq(02301_0f7c5f4a)]
 dom_name='DIAGAOT'
 isec=2
@@ -3720,6 +3854,70 @@
 tim_name='T3HMN'
 use_name='UPA'
 
+[namelist:umstash_streq(02301_5045b5d3)]
+dom_name='DIAGAOT'
+isec=2
+item=301
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02302_3c823c55)]
+dom_name='DIAGAOT'
+isec=2
+item=302
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02303_875ad30f)]
+dom_name='DIAGAOT'
+isec=2
+item=303
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02304_a6a633dd)]
+dom_name='DIAGAOT'
+isec=2
+item=304
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02305_43befd1e)]
+dom_name='DIAGAOT'
+isec=2
+item=305
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02530_a52da11d)]
+dom_name='D3DAR'
+isec=2
+item=530
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02540_025da8d5)]
+dom_name='D3DAR'
+isec=2
+item=540
+package=
+tim_name='TRAD'
+use_name='UPL'
+
+[namelist:umstash_streq(02585_c0486d2f)]
+dom_name='DIAGAOT'
+isec=2
+item=585
+package=
+tim_name='TRAD'
+use_name='UPL'
+
 [namelist:umstash_streq(03025_c8768f77)]
 dom_name='DIAG'
 isec=3
@@ -4190,6 +4388,25 @@
 !!unt2=2
 unt3=1
 
+[namelist:umstash_time(trad_acd872d3)]
+!!iedt=0
+iend=-1
+ifre=3
+!!intv=0
+!!ioff=0
+iopt=1
+!!isam=0
+!!isdt=0
+!!iser=0
+istr=1
+!!itimes=0
+ityp=1
+!!lts0=.false.
+tim_name='TRAD'
+!!unt1=1
+!!unt2=1
+unt3=1
+
 [namelist:umstash_use(upa_ffb3f00b)]
 file_id='pp0'
 locn=3
@@ -4256,6 +4473,12 @@
 !!macrotag=0
 use_name='UPK'
 
+[namelist:umstash_use(upl_b3d59e31)]
+file_id='pp11'
+locn=3
+!!macrotag=0
+use_name='UPL'
+
 [namelist:umstash_use(upukca_bde064da)]
 !!file_id=
 locn=6

These differences can be found here:

Tutorials/UMvn13.9/worked_solutions/Task06.1/Task06.1_ukca.patch

Sample output from this task can be found at

Tutorials/UMvn13.9/sample_output/Task06.1/

If you open the .pl file in Xconv, you should see the following additional fields:

0    : 96    72    1     2     field200: INCOMING SW RAD FLUX (TOA): ALL TSS 
1    : 96    72    1     2     field201: OUTGOING SW RAD FLUX (TOA)          
2    : 96    72    1     2     olr: OUTGOING LW RAD FLUX (TOA)
3    : 96    72    6     2     unspecified: AITKEN (SOLUBLE) ABS OPTICAL DEPTH      
4    : 96    72    6     2     unspecified: ACCUM (SOLUBLE) ABS OPTICAL DEPTH      
5    : 96    72    6     2     unspecified: COARSE (SOLUBLE) ABS OPTICAL DEPTH
6    : 96    72    6     2     unspecified: AITKEN (INSOL) ABS OPTICAL DEPTH 
7    : 96    72    6     2     unspecified: ACCUM (INSOL) ABS OPTICAL DEPTH 
8    : 96    72    6     2     unspecified: COARSE (INSOL) ABS OPTICAL DEPTH      
9    : 96    72    6     2     unspecified: MINERAL DUST OPTICAL DEPTH IN RADN. 
10   : 96    72    6     2     unspecified: AITKEN MODE (SOLUBLE) OPTICAL DEPTH 
11   : 96    72    6     2     unspecified: ACCUM MODE (SOLUBLE) OPTICAL DEPTH  
12   : 96    72    6     2     unspecified: COARSE MODE (SOLUBLE) OPTICAL DEPTH 
13   : 96    72    6     2     unspecified: AITKEN MODE (INSOL) OPTICAL DEPTH   
14   : 96    72    6     2     unspecified: ACCUM MODE (INSOL) OPTICAL DEPTH    
15   : 96    72    6     2     unspecified: COARSE MODE (INSOL) OPTICAL DEPTH   
16   : 96    72    38    2     unspecified: UKCA 3D AEROSOL EXTINCTION
17   : 96    72    38    2     unspecified: UKCA 3D AEROSOL EXTINCTION
18   : 96    72    38    2     unspecified: UKCA 3D AEROSOL EXTINCTION
19   : 96    72    38    2     unspecified: UKCA 3D AEROSOL EXTINCTION
20   : 96    72    38    2     unspecified: UKCA 3D AEROSOL EXTINCTION
21   : 96    72    38    2     unspecified: UKCA 3D AEROSOL EXTINCTION
22   : 96    72    38    2     unspecified: CLASSIC 3D AEROSOL EXTINCTION
23   : 96    72    38    2     unspecified: CLASSIC 3D AEROSOL EXTINCTION
24   : 96    72    38    2     unspecified: CLASSIC 3D AEROSOL EXTINCTION
25   : 96    72    38    2     unspecified: CLASSIC 3D AEROSOL EXTINCTION
26   : 96    72    38    2     unspecified: CLASSIC 3D AEROSOL EXTINCTION
27   : 96    72    38    2     unspecified: CLASSIC 3D AEROSOL EXTINCTION
28   : 96    72    6     2     unspecified: MINERAL DUST ABS. OPICAL DEPTH

Task 6.2: Calculate aerosol optical depth

TASK 6.2: Calculate the aerosol optical depth at 0.55 microns on the second radiation timestep.

Hint
The UM calculates optical depth diagnostics on 6 pseudo levels corresponding to 0.38, 0.44, 0.55, 0.67, 0.87, and 1.02 microns, therefore 0.55 microns is pseudo level 3.

Note: You will need to use the CLASSIC mineral dust optical depth diagnostic, as the configuration used in these tutorials does not use modal dust. Likewise, the insoluble accumulation and coarse mode diagnostics will be zero as these modes are not used in the configuration used here.

Python notebook

To calculate the total aerosol optical depth at 0.55 microns, you should sum up the contribution from the different aerosol components.

Example python notebooks to do this have been provided at

Tutorials/UMvn13.0/notebooks/iris_UM-UKCA_T062.ipynb

and can be seen online here

• iris_UM-UKCA_T062.ipynb

Solution to Task 6.2

• 

  0.55 micron AOD calculated from the component aerosol AOD diagnostics.

You were asked to

• Calculate the aerosol optical depth at 0.55 microns on the second radiation timestep.

and were given the hint

• The UM calculates optical depth diagnostics on 6 pseudo levels corresponding to 0.38, 0.44, 0.55, 0.67, 0.87, and 1.02 microns, therefore 0.55 microns is pseudo level 3.

You should make use of the python notebook provided to do this.

Sample output from this task can be found at

Tutorials/UMvn13.9/sample_output/Task06.2/

Task 6.3: Calculate the single-scattering albedo

TASK 6.3: Calculate the single-scattering albedo at 0.55 microns on the second radiation timestep, defined as:

$1-\left({\frac {{\textrm {Absorption}}\ {\textrm {Aerosol}}\ {\textrm {Optical}}\ {\textrm {Depth}}}{{\textrm {Aerosol}}\ {\textrm {Optical}}\ {\textrm {Depth}}}}\right)$

Python notebook

To calculate the single-scattering albedo at 0.55 microns, you should sum up the contribution to AAOD and AOD from the different aerosol components.

Example python notebooks to do this have been provided at

Tutorials/UMvn13.9/notebooks/iris_UM-UKCA_T063.ipynb

and can be seen online here

• iris_UM-UKCA_T063.ipynb

Solution to Task 6.3

• 

  0.55 micron single-scattering albedo.

You were asked to

• Calculate the single-scattering albedo at 0.55 microns on the second radiation timestep, defined as:

$1-\left({\frac {{\textrm {Absorption}}\ {\textrm {Aerosol}}\ {\textrm {Optical}}\ {\textrm {Depth}}}{{\textrm {Aerosol}}\ {\textrm {Optical}}\ {\textrm {Depth}}}}\right)$

You should use the python notebook provided to do this.

Sample output from this task can be found at

Tutorials/UMvn13.9/sample_output/Task06.3/

Task 6.4: Calculate the top of the atmosphere net downward radiative flux

TASK 6.4: Calculate the net downward top of the atmosphere radiative flux on the second radiation timestep.

Python notebook

To calculate the net TOA downward radiative flux, you should sum up the outgoing contributions from shortwave and longwave radiation, and take this away from the incoming shortwave radiative flux.

Example python notebooks to do this have been provided at

Tutorials/UMvn13.9/notebooks/iris_UM-UKCA_T064.ipynb

and can be seen online here

• iris_UM-UKCA_T064.ipynb

Solution to Task 6.4

• 

  Net downward TOA radiative flux.

You were asked to

• Calculate the net downward top of the atmosphere radiative flux on the second radiation timestep.

You should use the python notebook provided to do this.

Sample output from this task can be found at

Tutorials/UMvn13.9/sample_output/Task06.4/

Task 6.5: Calculate aerosol optical depth from the 3D aerosol extinction

TASK 6.5: Using the 3D aerosol extinction, calculate the 0.55 micron aerosol optical depth on the second radiation timestep, and compare this to your AOD from Task 6.2.

Hint
You will need to include contributions from both UKCA and CLASSIC (due to the dust scheme).
Remember to correctly calculate the grid-cell heights.

Python notebook

To calculate the AOD from the aerosol extinction, you will need to integrate this in the column. To do this you should first multiply by the height of each grid-cell before summing-up.

Example python notebooks to do this have been provided at

Tutorials/UMvn13.9/notebooks/iris_UM-UKCA_T065.ipynb

and can be seen online here

• iris_UM-UKCA_T065.ipynb

These scripts will also difference the two different methods.

Solution to Task 6.5

• 

  0.55 micron AOD calculated from the 3D extinction diagnostics.

• 

  Difference in AODs calculated by the two methods.

You were asked to

• Using the 3D aerosol extinction, calculate the 0.55 micron aerosol optical depth on the second radiation timestep, and compare this to your AOD from Task 6.2.

and were given the hints

• You will need to include contributions from both UKCA and CLASSIC (due to the dust scheme).
• Remember to correctly calculate the grid-cell heights.

You should use the python notebook provided to do this.

Sample output from this task can be found at

Tutorials/UMvn13.9/sample_output/Task06.5/

Checklist

☐ Make new time and domain profiles as needed.

☐ Run the TidyStashTransform transform macro.

☐ Output your diagnostics in STASH at: um $\rightarrow$ namelist $\rightarrow$ Model Input and Output $\rightarrow$ STASH Requests and Profiles $\rightarrow$ STASH Requests.

☐ When adding new aerosol diagnostics, remember to output on pseudo levels if appropriate.

☐ Run the TidyStashTransform transform macro again for the diagnostic requests.

☐ Save your suite.

☐ In the roses/[SUITE-ID] directory, run fcm commit to commit your changes to the repository.

☐ Python can be used to process and visualise Unified Model output.

Tutorial 7

UKCA Chemistry and Aerosol Tutorials at UMvn13.9

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Written by Luke Abraham 2025.