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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Hi, I'll jump in too. I work with global ocean modeling of biogeochemical tracers. In the past, because of computational cost, we have worked with low resolution models, which translated to horizontal dimensions of 100x116 and 25 vertical levels. We are now moving to higher resolutions, with our current target have a horizontal dimension of 320x384 with 60 vertical levels. Each 3D single precision field at this resolution uses ~28Mb, so 72 such fields fit into 2Gb and 145 fields fit into 4Gb. Or output module is designed to put all output fields into a single file that includes a record dimension, which is the time axis. Having the time axis be a record dimension eases later manipulation of the files with the NCO suite of tools. In classic netCDF format, we can only fit 72 3D fields into a record and this only doubles when moving to CDF2. Our biogeochemical module has 24 tracers and there are typically numerous diagnostic fields describing fluxes between each tracer field. When I started doing integrations with the higher resolution, I had to remove some diagnostic fields in order to fit within the 2Gb record limit. I resisted moving to CDF2 because of concern with typical tools being compatible with the new format. I am very concerned that switched to CDF2 only gains us a factor of 2. Our grid has an approximate resolution of 1 degree. Colleagues of mine regularly use 0.4 degree grids and 0.1 degree grids, and are forced to use binary formatted output. Given our current output architecture of having all fields in a single file, which our analysis tools are constructed for, CDF2 just won't get us much beyond where we are. If NetCDF doesn't transition allow larger records, in the near future we will either have to redesign our output and analysis tools, which is time consuming, or we won't be able to use NetCDF. I'm not looking forward to either option. Keith -- ****************************************************************** Keith Lindsay http://www.cgd.ucar.edu/oce/klindsay/ email: klindsay@xxxxxxxx phone: 303-497-1722 fax: 303-497-1700 ============================================================================== To unsubscribe netcdfgroup, visit: http://www.unidata.ucar.edu/mailing-list-delete-form.html ==============================================================================
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