Home > climate models > Call for PCCM2.1 / CCM2 T21L18 Double Precision Data Sets

Call for PCCM2.1 / CCM2 T21L18 Double Precision Data Sets

2012 March 9

Digging into Drake, et al, (1999), I noted that the model had been run for performance benchmarking at lower resolution. Digging back into the code, I found that the parameter that set the spectral power truncation was also used to reset lat/lon resolution. It was easy to recompile PCCM2.1 to a T21L18 resolution with a 4-fold reduction in cells (128×64 grid to 64×32 grid). That was the good news.

The bad news is that the freshly compiled program does not read the data sets for the T42 resolution model. I did find some data files for CCM2 on the UCAR ftp server, but they do not seem to be compatible with PCCM2.

There are four data files read by PCCM2.1 and I fired up ‘hexedit’ to read the tape headers.

379 PLX15 -T42 CASE379

TIMINV Time invariant boundary condition data

TIMEV Time variant boundary condition data

TIMEV Time variant boundary condition data

The UCAR FTP server is holding at least two sets of T21 files for CCM2, but these have a different header length, lack a ‘tvbds’ file, and are not read correctly by PCCM2.

  • t21.datasets.COS.0596
  • t21.datasets.IEEE.0596

If anyone has access to the original T21 double precision data files required by PCCM2.1 at T21L18 resolution, or knows how to convert the T42L18 data files, I would appreciate them dropping me a line at ronbroberg of yahoo.com or leaving a comment here.