Opened 4 weeks ago

Last modified 11 days ago

#3078 pending help

Creating (new) SST Ancillaries

Reported by: simon.tett Owned by: um_support
Component: UM Model Keywords:
Cc: Platform: Monsoon2
UM Version: 11.0

Description

Hi,

is there any documentation on creating SST ancillary files? The one I created causes a bunch of warnings and a crash on timestep 1.

ta
Simon

Attachments (2)

amipp4.job (12.9 KB) - added by simon.tett 4 weeks ago.
Job file for xancil
gen_amip4K.py (1.4 KB) - added by simon.tett 4 weeks ago.
Python script to make netcdf file for xancil to inout and convert

Download all attachments as: .zip

Change History (9)

comment:1 Changed 4 weeks ago by grenville

Simon

How was the sst file created - with xancil?

Grenville

Changed 4 weeks ago by simon.tett

Job file for xancil

Changed 4 weeks ago by simon.tett

Python script to make netcdf file for xancil to inout and convert

comment:2 Changed 4 weeks ago by simon.tett

Hi Grenville,

I am making them with xancil version 0.50 running on my local computer. I have a python script that reads the data and generates the netcdf file and then use xancil to make hte ancillary file. But sounds like process is the same as it has always been. I am getting a warning about grid stagger values from the UM (see below). Can't see any obvious way of setting this in xancil. Is the answer to ask Mike M to upgrade my version of xancil — if so what version?

Simon

????????????????????????????????????????????????????????????????????????????????
?????????????????????????????? WARNING ??????????????????????????????
? Warning code: -10
? Warning from routine: ANCIL_CHECK_GRID_STAGGER
? Warning message: Ancil file mismatch in fixed header(9) grid stagger value
? Model grid stagger = 6
? Ancil file grid stagger = 3
? Ancil file path = /home/d01/stett/data/qrclim.sstp4
? PLEASE READ - this warning will be converted to an error
? in future. Please update ancil file to specify the correct
? grid stagger value.
? Warning from processor: 0
? Warning number: 114
????????????????????????????????????????????????????????????????????????????????

comment:3 Changed 4 weeks ago by jeff

Hi Simon

Xancil gets it's grid from the input netCDF file, so you will have to generate this on the correct ENDGame grid.

A couple of things to look out for when creating a SST ancil file, make sure the ancil data covers the whole of the sea grid it's quite common for people to have missing data values on the sea points. Also it is a good idea to create the SST and Sea-Ice ancil together so they match with correct temperatures on ice points etc.

You can get the latest xancil from here, http://cms.ncas.ac.uk/documents/xancil/index.html#document-download. The latest version is 0.57

Jeff.

comment:4 Changed 4 weeks ago by simon.tett

Hi Jeff,

thanks for that. So probably some trouble in my python. This reads in the data fom the ancillary file, adds 4K onto it and writes it out again. So I don't change angthing about the grid.

This now turns into an iris/Endgame grid question. What meta-data do I need to provide to xancil so that it sets the right magic number in the header. Do I need to set up the boundaries as well? Which probbaly justs means copying them over from the input file.

Simon

comment:5 Changed 4 weeks ago by simon.tett

And a PS I looked at the co-ordinates (as iris sees them) and there are no boundry co-ordinates. And the time, longitudes & latitudes are the same in both the original ancillary file (as iris reds it in) and the output netcdf file…
Simon

comment:6 Changed 4 weeks ago by jeff

Hi Simon

Looking at the xancil source code, it will not set the header value correctly for endgame grids. I will have to add a switch to do this or for certain versions assume endgame is always being used. In the mean time this is just a warning so I don't think it is the cause of your problems.

Jeff.

comment:7 Changed 11 days ago by grenville

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