...
Expand | |||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||
The MARS application has been migrated to use GRIB API as its data decoder instead of GRIBEX. This migration has two components:
Because the interpolation software (libemos) uses extensively GRIBEX, many parts of the code had to be modified. Please see Field interpolation software for more information. For the migration of the MARS client we have tried, as much as possible, to avoid changes to the GRIB headers or the results. Extensive tests have been run and comparisons between interpolations of MARS/gribex and MARS/grib_api have been performed using
where the options have been chosen to skip differences smaller than twice the packing error. However, in some cases we have been unable to produce the same results. At the same time, we have found features of libemos/gribex (libemos using GRIBEX as data decoder) that have been corrected in libemos/grib_api (libemos using GRIB API as data decoder). Please see below for more details on known differences between MARS/gribex and MARS/grib_api. MARS client for installation in Member StatesFor a grib_api MARS client version 20110322 or higher should be used, which needs to be compiled with libemos 381 (or higher) and grib_api 1.9.9 (or higher), which can be freely downloaded. Known differences between MARS/gribex and MARS/grib_apiInterpolation of wavemediterraneanMediterranean fieldsThe interpolation of wave fields has been re-written. The new routine correctly recognizes sea points on the southernmost, last latitude for limited area wave fields. This has been verified by the wave experts. Libemos/gribex has not been fixed. Bitmaps and framesMARS/gribex doesn't initialise bitmaps (which are also used for frames), while MARS/grib_api initialises bitmaps to 0. Since bitmap arrays are filled differently, for bitmaps that do not fit a multiple of 8, the remaining bits can have different values. One can detect this difference by running grib_compare, which produces the following output: Different behaviour in MARS (not necessarily interpolation)
|
Attachments |
---|