Difference between revisions of "Solution to UKCA & UMUI Tutorial 3 Task 3.1"
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+ | There is a worked solution to this problem in the UMUI Tutorial experiment. This is job '''b''': ''Tutorial: solution to Task 3.1 - outputting a diagnostic''. |
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Revision as of 17:00, 14 June 2013
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.
The value of 10200 comes from the fact that you are requesting four 85 level variables for 30 days: 4x30x85=10200.
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 contain two files:
$ ls xipfba.pb19930901.pp xipfba.ph19930901.pp
Open the ph file. The varible list should look like
0 : 192 145 85 4 Stash code = 34001
Select this field and click the t radio button, which will list the times of each point in the field. This should give
1993/09/01:06.00 / 720.250000 1993/09/01:12.00 / 720.500000 1993/09/01:18.00 / 720.750000 1993/09/02:00.00 / 721.000000
Worked Solution
There is a worked solution to this problem in the UMUI Tutorial experiment. This is job b: Tutorial: solution to Task 3.1 - outputting a diagnostic.
Written by Luke Abraham 2013