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#52 fixed UM and ancillary files cwang umdoc

Dear all,

I need some help regarding UM and ancillary files. I have made a sea ice ancillary file using xancil0.40, taking into account the rotated pole. As an input I gave xancil sea ice concentration and sea ice depth but xancil calculated the se ice edge (basically giving every grid point the value -1.0737e+09 ).

I've then attempted to use the ancillary file in a LAM run, using data from a global run as boundaries and as ancillary files, with the exception of the land mask and the orography that were retrieved from BADC. My job is xckgb and can be found in /hpcx/devt/n02/n02-ncas/gnp/xckgb/ on the hpcx.

Now, when I run the UM the job fails in the first time step:

Atm_Step: Timestep 1 RHS zero so GCR( 2 ) not needed ==============================================

and then stops when Gathering fields, as most likely no fields to gather.

Do you have any idea what I'm not doing that I should be doing? Or how I could find out what's going wrong?

My own thoughts were that perhaps there were some incompatibilities between my new sea ice ancillary file and the rest of the variables in the restart file. The land mask is consistent with the sea ice and there is no sea ice over land. Is the sea ice edge a problem? I'm putting all my sea ice data into the sea ice concentration. Is there any documentation on sea ice ancillary files? Are there any other variables I should be worrying about?

Any help here would be greatly appreciated.




Guðrún Nína Petersen School of Environmental Sciences University of East Anglia Norwich UK

#53 fixed Documentation for the boundary layer in the UM ros g.n.petersen@…


Is there any documentation of the UM boundary layer? The document on the website, UM documentation 24, only discusses parametrization of turbulent fluxes above the surface but not any surface fluxes. I've found an old document called P24 that describes the sub-surface and surface fluxes. However, it's from 2000 and written for UM V4.5. Surely there have been some modifications to the surface fluxes since 2000??



#54 fixed Reconfiguring a global dump to A LAM dump - follow up (ticket 52) um_support g.n.petersen@…

Hi Chang,

sorry for sending this straight to you but I just want to clarify a few points because I'm not sure if I understand you entirely and I really want to get going, doing some proper runs :-)

  • You're suggesting that I reconfigure my global dump using ancillary

files for mask, orog, ice, soil and veg properties? As I don't want to change these at all, can I use the values from a start dump (reconfigured from the global dump) and make ancillaries for these? I am of course already using a orography ancillary file.

  • Do I also have to worry about the sst ancillary file? That is actually

the only one I have done tests with.

  • Do you suggest that any time one of these is changed ancillary files

for the others should be used in reconfiguration?

Thanks for pointing out that the standard ancillary files have -1.0737e09 as ice fraction over land. I hadn't picked up on that one.

Please let me know if you think of anything else I should consider.

All the best,


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