WORLD METEOROLOGICAL ORGANIZATION
COMMISSION FOR BASIC SYSTEMS
MEETING OF EXPERT TEAM ON DATA
REPRESENTATION AND CODES
MUSCAT, OMAN, 5 - 8 DECEMBER 2005
BUFR parameters for GEMS
ET DR&C/Doc. 3.9(1)
(15.XI.2005)
ENGLISH ONLY
Submitted by Martin Suttie (ECMWF)
________________________________________________________________
Summary and Purpose of Document
This document proposes a few new table B entries to represent aerosols and chemical species
________________________________________________________________
ACTION PROPOSED
The ET DR&C meeting is kindly asked to consider the proposed requirements.

1. BUFR table B entries for GEMS observational data
The GEMS ( Global and regional Earth-system Monitoring using Satellite and in situ data) project will develop and implement at ECMWF a comprehensive global data assimilation/forecast system for atmospheric dynamics and composition. The model will use all available data to achieve global monitoring. The monitoring will include atmospheric constituents including: a) greenhouse gases b) reactive gases c) aerosols
It is planned to use BUFR format for the representation and exchange of the observational data. In general, there is a need to represent chemicals in the BUFR form. The following table B entries are needed at this stage.
Key: xxxx element from proposal of Pelletier and Rochon yyyy new element needed
Aerosol
Parameter Units Table
Reference
0 01 007 Satellite identifier
0 02 019
0 01 033
0 02 172
0 04 001
0 04 002
0 04 003
0 04 004
0 04 005
0 04 006
0 05 001
0 06 001
0 27 001
Satellite instrument
Identification of originating/generating centre
Product type for retrieved atmospheric gases
Year
Month
Day
Hour
Minute
Second
Latitude (high accuracy)
Longitude (high accuracy)
Latitude (high accuracy) year month day hour minute second degree degree degree
0 28 001
0 27 001
0 28 001
0 27 001
0 28 001
0 27 001
0 28 001
0 07 025
Longitude (high accuracy)
Latitude (high accuracy)
Longitude (high accuracy)
Latitude (high accuracy)
Longitude (high accuracy)
Latitude (high accuracy)
Longitude (high accuracy)
Solar zenith angle degree degree degree degree degree degree degree degree

0 07 024
0 08 013
0 08 065
0 05 043
0 20 010
0 20 016
0 13 040
0 33 003
0 08 043
0 22 094
0 25 102
0 10 040
0 07 004
0 07 004
0 15 024
0 10 040
0 07 004
0 07 004
0 15 027
Satellite zenith angle
Solar azimuth angle
Satellite azimuth angle
Cloud mask and snow/ice indicator
Cloud amount percentage interval degree degree degree
Flag Table
Code Table
Day/night qualifier
Sun-glint indicator
Field of view number
Cloud cover (total)
Pressure at top of cloud
Surface flag
(with proposed addition - see below)
Quality information
Code Table
Code Table numeric
%
Pa
Code Table
Atmospheric chemical or physical constituent type
Aerosol optical depth at 0.55 micron
Error in aerosol optical depth at 0.55 micron (see Note
2)
Code Table numeric numeric
Ratio of small mode aerosol optical depth at 0.55 micron numeric
Error in ratio of small mode aerosol optical depth at 0.55 numeric micron (see Note 2)
Number of wavelength bands numeric
Per wavelength band
Spectrographic wavelength
Reflectance
Error reflectance (see Note 2)
Number of retrieved layers (for optical depth)
Per optical depth layer
Layer top pressure
Layer bottom pressure
Optical depth
Error optical depth (see Note 2)
Number of retrieved layers (for extinction)
Per extinction layer
Layer top pressure
Layer bottom pressure
Extinction coefficient
Error extinction coefficient (see Note 2)
Pa
Pa m
-1 m
-1 m numeric numeric numeric
Pa
Pa numeric numeric numeric

0 27 001
0 28 001
0 27 001
0 28 001
0 27 001
0 28 001
0 07 022
0 05 043
0 20 010
0 20 016
0 08 012
0 33 003
0 08 043
0 02 172
0 04 001
0 04 002
0 04 003
0 04 004
0 04 005
0 04 006
0 05 001
0 06 001
0 27 001
0 28 001
Chemical species
Initial GEMS chemical species are:

O
3
(ozone)
 NO
2
(nitrogen dioxide)
 SO
2
(sulphur dioxide)
 HCHO (formaldehyde)
 CO
2
(carbon dioxide)
 N
2
O (nitrous oxide)
 CO (carbon monoxide)
 CH
4
(methane)
Parameter Table
Reference
0 01 007
0 02 019
0 01 033
Satellite identifier
Satellite instrument
Identification of originating/generating centre
Product type for retrieved atmospheric gases
Year
Month
Day
Hour
Minute
Second
Latitude (high accuracy)
Longitude (high accuracy)
Latitude (high accuracy)
Longitude (high accuracy)
0 10 040
0 07 004
0 07 004
0 15 021
Latitude (high accuracy)
Longitude (high accuracy)
Latitude (high accuracy)
Longitude (high accuracy)
Latitude (high accuracy)
Longitude (high accuracy)
Solar elevation
Field of view number
Cloud cover (total)
Pressure at top of cloud
Land/sea mask
Quality information
Atmospheric chemical or physical constituent type (see
Note 1)
Number of retrieved layers
Per retrieved layer
Layer top pressure
Layer bottom pressure
Integrated mass density
Units numeric
Pa
Pa kg/m
2 year month day hour minute second degree degree degree degree degree degree degree degree degree degree degree numeric
%
Pa numeric
Code Table

0 07 004
0 07 004
Error integrated mass density (see Note 2)
No. of averaging kernel layers
Per averaging kernel layer
Layer top pressure
Layer bottom pressure kg/m
Pa
Pa
2 numeric
Averaging kernel value numeric
Notes:
1. Need CO, NO
2
, N
2
O, HCHO and SO
2
include in proposed Code Table 0 08 043.
2. We will have to be clear on what “error” means, i.e. could be 1-σ, 3- σ, rms, etc.

New BUFR descriptors for GEMS observational data
Table Reference Element Name
F X Y
015040
015041
015042
015043
015044
015045
015046
BUFR
Unit
Flag table
Code
Table
Scale Ref. value Data width
(bits)
Aerosol optical depth at 0.55 micron
(see Note A)
Ratio of small mode aerosol optical depth at 0.55 micron (see Note B)
Reflectance (see Note C) numeric 4 numeric 6 (4) numeric 6 (4)
No. of averaging kernel layers (see Note D) numeric
Averaging kernel value (see Note E)
0 numeric 6 (4)
Snow/ice indicator
Cloud amount percentage interval
0
0
0
CREX
Unit
24 numeric
Scale Data
4
0 20 (14) numeric 6 (4)
0 20 (14) numeric 6 (4)
-5x10
0
6
(-5x10 4 )
0
0
10 numeric
Width
(Chars)
8
7 (5)
24 (17) numeric 6 (4) 8 (6)
2 Flag table
3 Code
Table
0
0
0
7 (5)
4
1
1
Notes:
A. Assumed same range and precision as for Optical Depth (
0 15 024) proposed by Pelletier and Rochon.
B. Minimum value = 0.0, maximum value = 1.0, precision = 0.000001 (0.0001)
C. Minimum value = 0.0, maximum value = 1.0, precision = 0.000001 (0.0001)
D. Allow up to 1024 averaging kernel layers (as with Number of retrieved layers (0 10 040))
E. Minimum = -5.0, maximum = 5.0, precision = 0.000001 (0.0001)

New Flag Tables 015045
Cloud mask and snow/ice indicator
Bit No.
1
All 2
Snow/ice present
Missing value
New Code Tables 015046
Cloud amount percentage interval
Code figure
0
1
2
3
0-25% cloudy pixels
25-50% cloudy pixels
50-75% cloudy pixels
75-100% cloudy pixels
5-6
7
Reserved
Missing value
Additions to existing Code Tables
0 13 040 Surface flag
Code figure
0 Land
4
5
6
1
2
3
Reserved
Near coast
Ice
Possible ice
Ocean
Coast
7
8-14
15
Desert
Reserved
Missing value
Additions to proposed Code Tables
0 08 043 Atmospheric chemical or physical constituent type
Code figure
0
1
Ozone (O
3
)
Water vapour (H
2
O)

2
3
4
5
6
7
8
9-24
Methane (CH
4
)
Carbon dioxide (CO
2
)
Carbon monoxide (CO)
Nitrogen dioxide (NO
2
)
Nitrous oxide (N
2
O)
Formaldehyde (HCHO)
Sulphur dioxide (SO
2
)
Reserved
25
26
27
28
29
30
31
32
Particulate matter < 1.0 microns
Particulate matter < 2.5 microns
Particulate matter < 10 microns
Aerosols (generic)
Smoke (generic)
Crustal material (generic dust)
Volcanic ash
Continental (generic)
33
34
Maritime (generic)
Sulfate
35-200 Reserved
201-254 Reserved for local use
255 Missing value
8