defs['SLCAAAZX'] = 'Concentration of silicate {SiO4} per unit volume of the water body [unknown pha>'
    defs['SSALAGT1'] = 'Salinity of the water body by titration against silver nitrate (AgNO3)'
    defs['SSALBSTX'] = 'Salinity of the water body by bench salinometer'
    defs['TEMPPR01'] = 'Temperature of the water body'
    defs['TPHSPP01'] = 'Concentration of phosphorus (total) per unit volume of the water body [dissolve>'

    lon, lat = [-4.83333], [54.09167]

    data = {}

    zlev = []
    indices = [0]
    duration = 0

    for file in ncs:
        nc, ga = readFVCOM(os.path.join(base, 'raw_data', file), globalAtts=True)
        k, _ = os.path.splitext(file)

        nc['indices'] = int(ga['dims']['primary'].split(':')[-1])
        duration += nc['indices']
        indices.append(indices[-1] + nc['indices'])
        zlev.append(int(ga['dims']['secondary'].split(':')[-1]))

        data[k] = nc

    zlev = np.unique(zlev)
    if len(zlev) > 1:
        raise Exception('Non-uniform depth levels, so I can\'t concetenate these netCDFs.')

    # Now find all the unique keys for each file so we can find out how many
    # different variables we have.