MARS

Specifies the number of bits per value used in the target GRIB messages.

accuracy=<value>

A positive integer may be given to specify the preferred number of bits per packed value. This must not be greater than the number of bits normally used for a Fortran integer on the processor handling the request (typically 32 or 64 bit).

The archived accuracy is specific for each parameter and in general not identical to the default accuracies used in dissemination. MARS and dissemination are therefore not always in sync: to reproduce from MARS the values received through dissemination, request the same accuracy=n that was used in dissemination. The accuracy of fields in a grib file can be found using the ecCodes command:

grib_ls -P bitsPerValue <grib_file>

Fields resulting from a MARS compute request are by default coded with 24 bits per value. To set the accuracy of the result field to that of the first field used in the formula, accuracy=av can be specified.

Dissemination

Specifies the number of bits per value used in the target GRIB messages.

accuracy=<value>

A positive integer may be given to specify the preferred number of bits per packed value. This must not be greater than the number of bits normally used for a Fortran integer on the processor handling the request (typically 32 or 64 bit).

If accuracy is not specified, the dissemination system applies its own accuracy for each parameter. For some parameters this differs from the accuracy of the field archived in MARS, so MARS and dissemination are not always in sync: the same field received through dissemination and retrieved from MARS may not have identical values. To receive the archived accuracy, specify accuracy=av in the dissemination request; this is safe to set for all parameters. The accuracy of fields in a grib file can be found using the ecCodes command:

grib_ls -P bitsPerValue <grib_file>

Examples