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Some formats, such as GRIB, are easy to visualise in Metview - just right-click, Visualise. This is because they are quite constrained in their contents and have enough standardised meta-data for a program to understand how they should be plotted. Some other formats, such as netCDF and tables of ASCII data are not easily interpreted for automatic plotting (which variables/columns should be selected and what do they represent?). Metview introduces the concept of the Visualiser icon, which we will use in some of the following examples.

NetCDF

NetCDF is a binary file for storing multi-dimensional arrays of data and has enjoys wide academic usage.

Examining netCDF

Right-click on the supplied netcdf.nc icon and choose examine to see its structure. It consists of multi-dimensional variables, each of which has its own set of attributes; the file also has a set of global attributes.

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nc = read('netcdf.nc')
print('Variables: ', variables(nc))
print('Global attributes: ', global_attributes(nc))

Exporting Cross Sections and Profiles as netCDF

Metview uses netCDF internally for the results of some computations. In particular, the analysis views do this, but their result data is not available to the user. Therefore, each of these views has a corresponding Data view - for example, there exist both a Cross Section View and a Cross Section Data icon. If the intention is to simply plot the result, then the View icons are more useful. But to store the result data, the Data icon is neededrequired.

Create both a Cross Section View and a Cross Section Data icon and edit both to see the differences. All the parameters related to the visualisation of the result are only in the View icon, and the Data parameter exists only in the Data icon.

Dealing only with the Data icon now, drop the supplied input GRIB icon t_atmos.grib into the Data parameter box.

Geopoints

Geopoints is the ASCII format used by Metview to handle spatially irregular data (e.g. observations). There are a number of variations on the format, but the default one is a 6-column layout. The columns do not have to be aligned, but there must be at least one whitespace character between each entry.

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