Solution to UKCA & UMUI Tutorial 3 Task 3.1

Back to the what is STASH? tutorial

Task

You were asked to

Output the instantaneous UKCA ozone field to the ph/UPH stream every 6 hours.

and were given the hint

You will need to make the changes to the STASH table first, and remember to use Verify Diagnostics. You may then need to change the frequency of output.

Solution

Step 1: Add the new diagnostic to the STASH table

You will need to add the following to the STASH table

34   1 O3 MASS MIXING RATIO AFTER TIMESTEP T6H      DALLTH   UPH      Y +  Y  

i.e.

• Time Profile = T6H
• Domain Profile = DALLTH
• Usage Profile = UPH

Verify the Diagnostics

Verifing the diagnostics (either Control-v or Diagnostics → Verify Diagnostics) gives

PP-Field Count Estimates  


Warning!!! You may exceed the maximum number of PP fields per file
	      
Estimated number of PP files to be written:

10200 fields in stream 67.  Maximum allowed is 4096.
11647 fields in Climate mean Period_1
11647 fields in Climate mean Period_2
11647 fields in Climate mean Period_3
11647 fields in Climate mean Period_4

Maximum allowed is 4096 fields per Climate Mean Period.

You don't need to worry about the Climate Mean Period here, and in fact this job will run perfectly happily with this many fields.The line that is of more concern is

10200 fields in stream 67.  Maximum allowed is 4096.

Fix

There are two ways to fix this. They both need you to go to Model Selection → Post Processing → Initialization and processing of mean and standard PP files.

Method 1: Increase the Override size

Increasing the value in the Override size column from 0 to 16000 for the PP7/PH/67 stream will remove this error. However, the Help text explicitly states here

Override size. Fieldsfiles usually can only contain 4096 fields. The recommended way to work around this restriction is to use periodic re-initialisation of the fieldsfiles. In the rare case that this is not a suitable option (e.g. for analysis time in a forecast) it is possible to extend the 4096 field restriction by overriding the default size. Be careful not to override the size by too much - large numbers of fieldsfile headers can be inefficient for both runtime and memory use and may cause problems with some small executables.

So the UMUI is explicitly suggesting that the frequency of output should be altered. This is Method 2.

Method 2

In this method we change the Period from 30 to 1, i.e. there will be a new file created every day.

We will use Method 2.

Step 2: Turn on archiving

Because the UPH profile is not currently in use prior to this change, the UMUI has set the stream not to archive. Go to the Model Selection → Post Processing → Initialization and processing of mean and standard PP files panel and change the N to Y for the PP7/PH/67 stream. As you have requested this diagnostic in the STASH panel the UMUI will keep this preference.

Note: if you had tried to turn archiving on before you had requested the diagnostic in STASH, the UMUI may not have remembered this preference.

Submit

Now save, process, and submit your job. When the job has run the output in your archive directory will now be

Open the ph file. It should look like

---

Written by Luke Abraham 2013