Appendix 1. Convsh commands

Below is a list of convsh extensions to the tcl scripting language. Some commands have the argument fieldlist, this is a list of numbers which represents a subset of the fields which convsh has stored in memory. These fields will be stored in the same order as they are in xconv, therefore the easiest way to work out the field numbers is to run xconv on one file, before applying a convsh script to a large number of files. Remember field numbering starts at 0.

clearall

Clears away all internal information about previous input files. This command must be used if a separate output file is needed for every input file.

copyfields fieldlist

Make a copy of all the fields in fieldlist. Note the field numbers will be changed by this command. For example if the original fields are (a,b,c,d,e) mapped on to field numbers (0,1,2,3,4), after the command copyfields "1 3", the new fields will be (a,b,b,c,d,d,e) mapped on to field numbers (0,1,2,3,4,5,6).

delfields fieldlist

Delete all the fields in fieldlist. Note the field numbers will be changed by this command. For example if the original fields are (a,b,c,d,e) mapped on to field numbers (0,1,2,3,4), after the command delfields "1 3", the new fields will be (a,c,e) mapped on to field numbers (0,1,2).

interp_grid fieldlist

Interpolate data, for fields in fieldlist, from one grid to another. The initial grid will either be the grid the data was read in on, or the grid from a previous interp_grid or spec_trans command. If a new grid is not defined using setgrid or settrunc, the new grid will be the same as the initial grid.

list_fields [fieldtitle]

List all of the fields currently active in convsh. The output format is the same as in the main xconv window. The fieldtitle argument is optional, it can have three values short, long and both. short uses the short form of the field title, long uses the long form and both uses both. If fieldtitle is not given the long form of the field title is used.

readfile filetype filename

Read into convsh the file given by filename, the file type is given by the filetype argument. If filetype has the value 0 convsh will try to automatically determine the file type, this will usually work but if it fails the actual file type can be given. The various values of filetype for different input file types are given below:

0 : Automatic
1 : UM format (32 bit IEEE)
2 : PP format (32 bit IEEE)
3 : GRIB format (Unblocked)
4 : GRIB format (Cray blocked)
5 : Drs format
7 : Netcdf format
65 : UM format (64 bit IEEE)
66 : PP format (64 bit IEEE)
165 : UM format (64 bit Cray)
166 : PP format (Cray blocked 64 bit Cray)
167 : PP format (Cray blocked 64 bit IEEE)
201 : UM format (32 bit IEEE byte swapped)
265 : UM format (64 bit IEEE byte swapped)

reset_trans

Reset transformation/interpolation variables to their default values. See the individual commands for the default values.

setdim dim fieldlist dimlist

Choose the values given by dimlist for the dimension given by dim, for the fields in fieldlist. The value of dim should be one of 1,2,3 or 4 corresponding to the x,y,z and time dimensions. Currently convsh only allows dimension sub-sampling for the z and time dimensions, therefore dim should be either 3 or 4. As an example suppose field number 2 has the following levels (1000,900,800,500,200,100) defined and only levels (1000,500,100) were needed, then the following should be used: setdim 3 2 "0 3 5".

setgrid dim n v0 dv

Defines the new grid for the interp_grid or spec_trans commands. The argument dim should have the value 1 if a new x grid is being defined and the value 2 if a new y grid is being defined. The argument n gives the number of points on the new grid. The argument v0 gives the first value of the new grid. The argument dv gives the grid length of the new grid, dv should be negative if the grid values are decreasing.

setgridtype gridtype

Sets the new grid type for the interp_grid or spec_trans commands, gridtype has the value regular for a regular grid and the value gaussian for a Gaussian grid. If setgridtype is not used interp_grid will interpolate to a regular grid and spec_trans will transform to a Gaussian grid.

setinterp interp

Defines the interpolation method for interp_grid, interp is either bilinear for bilinear interpolation or area_weighted for area weighted interpolation. The default type of interpolation is bilinear.

setlsm lsm

Defines whether the input data to interp_grid is a land/sea mask, lsm is true if the data is a land/sea mask, false otherwise. The default value of lsm is false.

setmiss miss

Defines whether the input data to interp_grid contains missing data values, miss is true if the data contains missing data values, false otherwise. The default value of miss is false.

setpole pole

Defines whether interp_grid will average polar data values, if pole is true then polar data will be averaged, otherwise it will not. The default value of pole is false.

setprecip precip1 precip2

Defines whether interp_grid will use a precipitation cutoff, if precip1 is true then a precipitation cutoff value of precip2 will be used, otherwise no precipitation cutoff is used. The precipitation cutoff is implemented in two steps, firstly any output field value less than precip2 will be set to zero. Secondly, for each output gridpoint, the nearest input field gridpoint is determined, if the value of precipitation at this latter point in the input data field is less than precip2, then the precipitation at the output gridpoint is set to zero. The default value of precip1 is false.

setrotpole xpole ypole

If interp_grid is interpolating to a grid with a rotated pole, setrotpole should be used to set the new north pole longitude to xpole and the new north pole latitude to ypole. By default xpole has the value 0.0 and ypole has the value 90.0 i.e. an unrotated grid.

settrunc nspec

Defines the output truncation for spec_trunc. The command will also set up the equivalent Gaussian grid for Tnspec truncation, which can be used by interp_grid and spec_trans.

spec_trans fieldlist

Transform spectral data onto a grid, for fields in fieldlist. The initial spectral coefficients will either come from the input data or from a previous spec_trunc command. If a grid is not defined using setgrid or settrunc, then the equivalent Gaussian grid for the input spectral truncation will be used.

spec_trunc fieldlist

Truncate spectral data, for fields in fieldlist, by chopping off the small wavelength coefficients. The initial spectral coefficients will either come from the input data or from a previous spec_trunc command. The output truncation is defined using settrunc.

writefile filetype filename fieldlist

Write out the fields in fieldlist to file filename of type filetype. The argument filetype can be one of drs, netcdf or utf.