Introduction

This document should describe the input data for TM5, and how it is created.

File name conventions

A TM5 meteo file is named following the naming convention for ECMWF files (section 2.2.2):

<class>/<type>/<year>/<month>/<levtype>[<nlev>]/<grid>/<param>_<date>[<fckey>]_<times>.gb

Example:

od/fc/2002/10/ml60/glb3x2/uvsp_20021018_21p06.hdf

Overview of the keys in the filename:

<class>

Data class:

• od : operational data
• e4 : 40 year reanalysis

<type>

Data type:

• fc : forecast
• fg : first guess
• an : analysis
• 4v : 4D var analysis

<levtype>[<nlev>]

Level type:

• sfc : surface
• ml : model levels;
  if a 2D ECMWF fields available is only on model levels (for example LNSP), then the derived TM field is denoted by 'ml' too (for example surface pressure)

The number of levels is included for level types other than 'sfc'.

<grid>

key for horizontal resolution: gl6x4, sam3x2, ...
see 4.1.2

<param>

key for the parameters storred in the file: uvsp, t, q, ...

<date>

day for which data is valid in 'ccyymmdd' format

<fcday>

optional forecast day with format 'f<ndays>';
for example '20020618f05' denotes a 5 days forecast valid for 18-06-2002.

<times>

time resolution key:

• 00p03 : first field valid for hour 00:00, increments of 03 hour

<format>

output format : gb (grib) or hdf

Idea is that 'day' specifies the day for which the data is valid, and the postfix distinquishes between different forecasts valid for that day. No postfix simply means 'the best available data'; this could be 4d var data but also a forecast over a few hours.

A simple convention to have a file name containing a complete description of the contents is to replace all '/' in the full path with '-' :

od-4v-2002-06-ml60-glb3x2-uvsp_20020618_03p03.gb

To achieve this in csh, use for example the sed command:

set fullpath = od/4v/2002/06/ml60/glb3x2/uvsp_20020618_03p03.gb
set longname = `echo $fullpath | sed -e 's^/^-^g'`

and for the reverse:

set longname = od-4v-2002-06-ml60-glb3x2-uvsp_20020618_03p03.gb
set fullpath = `echo $longname | sed -e 's^-^/^g'`

Horizontal grids

Different sets of TM meteo are identified by the 'grid name'. The grid name occures in the directory and file names used to store the meteo.

Examples of grid names are 'glb3x2', 'gl6x4', 'sur1x1'. There is no real convention, but a few characters followed by the lon/lat resolution in degrees is suitable.

TM5 uses a regular lat/lon grid with different resolutions.

TM3 used to be centered over the date line; in the new version, the dateline is the western border.

TM5 grid position	TM3 grid position

Vertical levels

TM5 levels are always formed following the ECMWF levels. Optionally, some levels are combined into a single level.

The level ranges are defined in two source files:

• SOURCE/tmpp_const_ec_v_<nlev>.f90
  Defines the ECMWF levels.
• SOURCE/tmpp_const_tm_v_<nlev>.f90
  Defines the TM5 levels as a combination of ECMWF levels.

Currently implemented TM levels are:

nlev	used by	description
60	parent data set	All ECMWF levels
44	TM3dam (Henk, Arjo)	low resolution in troposphere
33	TM-SCIA (Michiel, Ernst), TM5 (Bram)	double layers (close to original ECMWF 31 layers)
25	TM5 (Maarten)
1	general purpose	surface fields

Time resolution

With the files for one day the TM models can be run from 21h on the former day until 21h of the day itself.

Field description in output files

Fields are stored in the files with the following description:

• levels are storred surface to top (TM order)
• lat/lon indices specfify:
  • by default:
    • lat/lon indices in files denote center of grid cell
    • time key is single hour
  • eastward fluxes 'pu' (see also 4.5):
    • fields contain 'extra' row for west boundary, thus dimension(0:im,jm,lm)
    • lat/lon indices in files denote mid of east/west boundary
    • fields are valid for 6 hr, time denotes the start of the interval
  • northward fluxes 'pv' (see also 4.5):
    • fields contain 'extra' row for norht boundary, thus dimension(im,0:jm,lm)
    • lat/lon indices in files denote mid of norht/south boundary
    • fields are valid for 6 hr, time denotes the start of the interval
• no special treatment of pole cells: files contain suitable values even for the triangular shaped pole cells.