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NOAA KLM User's Guide

Section 9.4.2
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9.4.2 AMSU-B Sounding Products

In addition to the ATOVS products, NOAA KLM also generates AMSU-B data from which moisture products are generated. The AMSU-B instrument has a FOV of 15 km. The data generated from the AMSU-B instrument is sampled by skipping every other FOV. This generates a product of about 30 km spacing with a maximum of 100,000 retrievals per orbit.

Each archive file consists of all valid sounding data extracted from the original retrieval file for the most recent AMSU-B orbit. Except for the header record, an orbit archive file has all integer terms with data values scaled by numbers such as 64 and 128. The archive file has a block size of 10,720 bytes with record lengths of 268 bytes. The first record of the database is the header (see Table 9.4.2-1) which provides information such as the last record written and the number of records. The header record uses I*4 words and is the same size as the data records (268 bytes).

Table 9.4.2-1. Header Record Format of Orbit Archive File.
Starting Byte I*4 Location Length (bytes) # of values Description
1 1 4 1 Number of data records in the file
5 2 4 1 First data record written in file (2)
9 3 4 1 Last data record written
13 4 4 1 Logical record length
17 5 4 1 Spacecraft ID
21 n/a 3 1 File type (RET)
25 n/a 8 1 Satellite name (NOAA- xx)
34 n/a 44 1 File name
79 n/a 10 1 File creation date (YYYYMMDDHH)
89 23 4 1 Beginning orbit number
93 24 4 1 Ending orbit number
97 25 4 1 Time of first retrieval (YYYYMM)
101 26 4 1 Time of first retrieval (DDHH)
105 27 4 1 Time of first retrieval (mmss)
109 28 4 1 Time of last retrieval (YYYYMM)
113 29 4 1 Time of last retrieval (DDHH)
117 30 4 1 Time of last retrieval (mmss)
121 31- 67 4 1 Spares

Records 2 through N (the number of records) contain the retrieval records. Table 9.4.2-2 contains the format of the retrieval data records.

Table 9.4.2-2. Format of Orbit Archive File Retrieval Data Records.
Starting byte I*2 Location Length (bytes) # of values Scaling Factor Description
1 1 2 1 1 Record type (2=data record)
3 2 2 1 1 FOV number in the scan line
5 3 2 1 1 Spare
7 4 2 1 1 Orbit number
9 5 2 1 1 FOV time (YYMM)
11 6 2 1 1 FOV (DDHH)
13 7 2 1 1 FOV (mmss)
15 8 2 1 128 FOV latitude (degrees)
17 9 2 1 128 FOV longitude (degrees)
19 10 2 1 128 Solar zenith angle (degrees)
21 11 2 1 128 Satellite zenith angle (degrees)
23 12 2 1 1 Terrain type
0=sea;
1=land;
2=coast;
16=ice;
17=snow.
25 13 2 1 1 Surface elevation (m)
27 14 2 1 1 Surface pressure (mb)
29 15 2 1 64 Skin temperature (K)
31 16 2 1 1 Day/Night indicator
0=night,
1=day.
33 17 2 3 1 Channel combination flag
39 20 2 1 1 Observation quality flag
41 21 2 15 1024 Natural log of AMSU-B water vapor mixing ratios (g/kg)
71 36 2 5 64 Limb corrected AMSU-B temperatures (K)
81 41 2 5 64 Bias Corrected observed AMSU-B temperatures (K)
91 46 2 5 64 First Guess bias corrected AMSU-B temperatures (K)
101 51 2 15 1024 Natural log of first guess water vapor mixing ratios (g/kg)
131 66 2 1 1 First Guess temperature profile flag
133 67 2 40 64 First Guess temperature profile
213 107 2 7 64 Spares
227 114 2 1 1 Forecast increment
229 115 2 1 64 Forecast potential temperature (K)
231 116 2 1 64 Forecast surface air temperature (K)
233 117 2 1 10 Forecast surface pressure (mb)
235 118 2 1 1 Forecast relative humidity (%)
237 119 2 1 1 Retrieval - forecast time difference
239 120 2 1 100 Cloud liquid water (cm)
241 121 2 3 100 Layer precipitable water (cm)
247 124 2 1 64 First Guess skin temperature (K)
249 125 2 1 64 First Guess surface temperature (K)
251 126 2 1 10 First Guess surface pressure (mb)
253 127 2 1 1 First Guess relative humidity (%)
255 128 2 1 1 Scan number
257 129 2 5 64 AMSU-B antenna temperature (K)
267 134 2 1 100 Total precipitable water (cm)

9.4.2.1 AMSU-B Metadata Archive File

The AMSU-B Metadata Archive File is a rotating file. The first record is updated each week and contains the start date (year, month, and day of the next week's data, the next available record and the maximum records on the file). The metadata archive file consists of a header record (1,000 bytes), followed by two data files for each week of metadata statistics: one file contains mixing ratio statistics, the other file contains brightness temperature statistics. Table 9.4.2.1-1 contains the format for the header record of the AMSU-B metadata archive file. Tables 9.4.2.1-2 and 9.4.2.1-3 contain the formats of the data files.

Table 9.4.2.1-1. Format of the header record of the AMSU-B metadata archive file.
Start Byte Data Type # of values Length (bytes) Dimension Description
1 C 1 1 n/a Spare
2 C 1 10 I10 Next beginning year
11 C 1 10 I10 Next beginning month
21 C 1 10 I10 Next beginning day
31 C 1 10 I10 Next record on file to write to
41 C 1 10 I10 Maximum record on file to write to
51 C n/a 950 n/a Spares

Table 9.4.2.1-2. Format of AMSU-B Metadata Archive File, Data Record A (Mixing Ratios) (15,4,6).
15 levels (300, 350, 400, 430, 475, 500, 570, 620, 670, 700, 780, 850, 920, 950, 1000 mb)
4 statistics (1 - mean, 2 - root mean square, 3 - standard deviation, 4 - sample size)
6 zones (90.0 to 60.0, 60.0 to 30.0, 30.0 to 0.0, 0.0 to -30.0, -30.0 to -60.0 and -60.0 to-90.0 degrees latitude)
Start Byte # of values Length (bytes) Dimension Description
1 1 6 I*6 File record number
7 1 6 I*6 Beginning year of data
13 1 6 I*6 Beginning month of data
19 1 6 I*6 Beginning day of data (total of 7 days of data)
25 1 36 A*36 Information Character (i.e., MIXING RATIO STATISTICS)
61 360 780 (15,4,6) Mixing Ratio Statistics
90 180 (1,1,1) Mixing ratio mean difference from RAOB
90 180 (1,2,1) Root mean square
90 180 (1,3,1) Standard Deviation
90 180 (1,4,1) Sample Size
781 n/a 220 n/a Spares

Table 9.4.2.1-3. Format of AMSU-B Metadata Archive File, Data Record B (Brightness Temperatures) ( 5,4,6).
5 channels (channels 1 through 5)
4 statistics (1 - mean, 2 - root mean square, 3 - standard deviation, 4 - sample size)
6 zones (90.0 to 60.0, 60.0 to 30.0, 30.0 to 0.0, 0.0 to -30.0, -30.0 to -60.0 and -60.0 to-90.0 degrees latitude)
Start Byte # of values Length (bytes) Dimension Description
1 1 6 I*6 File record number
7 1 6 I*6 Beginning year of data
13 1 6 I*6 Beginning month of data
19 1 6 I6 Beginning day of data (total of 7 days of data)
25 1 36 A*36 Information Character (i.e., BRIGHTNESS TEMP STATISTICS)
61 120 300 (5,4,6) Brightness Temperature Statistics
30 60 (1,1,1) Brightness Temperature Mean difference from RAOB derived
30 60 (1,2,1) Root mean square
30 60 (1,3,1) Standard Deviation
30 60 (1,4,1) Sample Size
301 n/a 700 n/a Spares

9.4.2.2 AMSU-B Radiosonde Match Archive

A new radiosonde match archive file is created once a month. Each archive file consists of all valid retrieval-radiosonde matches extracted from the AMSU-B Match Archive for the previous month. Except for the header record, the radiosonde match archive file is in all integer format with data values either unscaled or scaled by values from 64 to 1024. The header record provides information such as the last record written and the number of records. All integer values in the header are four bytes long. The records are 2,484 bytes in length with a block size of 27,324 bytes. Table 9.4.2.2-1 contains the format of the header record and Table 9.4.2.2-2 contains the format of the data records for the radiosonde match archive file. In the data records, real values have been stored in I*2 format after first multiplying the real value by the scaling factor.

Table 9.4.2.2-1. Format of Header record for AMSU-B Radiosonde Match Archive File.
Starting Byte I*4 Location Length (bytes) # of values Description
1 1 4 1 Number of data records in the file
5 2 4 1 First data record written in file (2)
9 3 4 1 Last data record written
13 4 4 1 Logical record length
17 5 4 1 Spacecraft ID
21 n/a 3 1 File type ('ARC')
25 n/a 6 1 Satellite name ('NOAA xx')
31 n/a 1 3 Spares
34 n/a 24 1 File name
58 n/a 1 3 Spares
61 n/a 8 1 File creating date (YYYYMMDD)
69 n/a 20 1 Spare
89 23 4 1 Time of first retrieval (YYYYMM)
93 24 4 1 Time of first retrieval (DDHH)
97 25 4 1 Time of first retrieval(mmss)
101 26 4 1 Time of last retrieval (YYYYMM)
105 27 4 1 Time of last retrieval (DDHH)
109 28 4 1 Time of last retrieval (mmss)
113 29-621 4 2368 Spare

Table 9.4.2.2-2. Format of Data record for AMSU-B Radiosonde Match Archive File.
Start Byte Integer Location Length (bytes) # of values Scale Description
1 n/a 6 1 1 Radiosonde station ID
7 4 2 1 128 Station latitude (-90 to 90 degrees)
9 5 2 1 128 Station longitude (-180 to 180 degrees)
11 6 2 1 1 Station elevation (m)
13 n/a 8 1 1 Satellite ID ('NOAA xx')
21 11 2 1 128 Retrieval latitude (-90 to 90 degrees)
23 12 2 1 128 Retrieval longitude (-180 to 180 degrees)
25 13 2 3 1 Retrieval time (see Note 1)
31 16 2 1 1 Orbit Number
33 17 2 1 1 Beam position
35 18 2 1 1 Archive flag (1=archived)
37 n/a 1 2 1 Spare
Satellite Observations:
39 20 2 1 128 Solar Zenith angle (degrees)
41 21 2 1 128 Satellite Zenith angle (degrees)
43 n/a 1 1 1 Terrain flag
0=sea,
1=land,
2=coast,
10=sea ice,
11=snow
44 n/a 1 1 1 Spare
45 23 2 1 1 Surface Elevation (m)
47 24 2 1 1 Surface Pressure (mb)
49 25 2 1 64 Mapped skin temp (NCEP SST) (K)
51 n/a 1 1 1 Day/night flag
0=night,
1=day
52 n/a 1 6 1 Channel combination
58 n/a 1 1 1 Observation quality flag (see Note 2)
59 30 2 15 1024 Retrieved water vapor mix ratios (see Note 3) (g/kg)
89 45 2 5 64 Limb corrected brightness temperatures (K)
99 50 2 5 64 Bias corrected brightness temperatures (K)
109 55 2 5 64 First Guess brightness temperatures (K)
119 60 2 15 1024 First Guess mixing ratios (see Note 3) (g/kg)
149 75 1 1 1 First Guess temperature profile flag
150 n/a 1 1 1 Spare
151 76 2 40 64 First Guess atmospheric temperatures (K) (set to missing)
231 116 2 7 1 Spares
245 123 1 1 1 Forecast increment
246 n/a 1 1 1 Extrapolation flag (set to '0')
247 124 2 1 64 Forecast potential temperature (K)
249 125 2 1 64 Forecast surface air temperature (K)
251 126 2 1 10 Forecast surface pressure (mb)
253 127 2 1 1 Forecast relative humidity (%)
255 128 2 1 1 Retrieval-Forecast time difference
257 129 2 1 100 Cloud liquid water (g/cm -see Note 3 )
259 130 2 3 512 Layer precipitable water (cm)
265 133 2 1 64 First Guess potential temperature/surface air temperature (K)
267 134 2 1 1 First Guess humidity (%)
269 135 2 1 64 First Guess skin temperature (K)
Interpolated Radiosonde Profile:
271 136 2 40 64 Interpolated atmospheric temperatures (K)
351 176 2 15 1024 Interpolated water vapor mixing ratios (g/kg - see Note 3)
381 191 2 1 64 Interpolated tropopause temperatures (K)
383 192 2 1 1 Interpolated tropopause pressure (mb)
385 193 2 1 1 Interpolated surface pressure (mb)
387 194 2 1 64 Interpolated surface temperature (K)
389 195 2 1 1024 Interpolated surface mixing ratio (g/kg - see Note 3)
391 196 2 1 100 RAOB profile used:
0=preceding RAOB used
1=succeeding RAOB used
393 197 2 5 64 Simulated RAOB brightness temperatures (K)
403 202 2 1 1 Highest level reached by RAOB
405 203 2 1 1 Lowest level reached by RAOB
407 n/a 1 1 1 Primary/secondary matchup flag:
1=primary;
2=secondary.
408 n/a 1 12 1 Screening flags
420 n/a 1 1 1 Spare
421 211 2 3 100 Layer Precipitable Water (cm)
427 214 2 1 100 Total Precipitable Water (cm)
429 n/a 1 8 1 Spare
Preceding Radiosonde Station Report:
437 n/a 6 1 1 Radiosonde station ID
443 n/a 2 3 1 Day of synoptic report (see Note 4)
449 n/a 2 3 1 Balloon release date (see Note 5)
455 228 2 1 100 Observation time (UTC hours)
457 229 2 1 128 Latitude (-90 to 90 degrees)
459 230 2 1 128 Longitude (-180 to 180 degrees)
461 231 2 1 1 Station elevation (m)
463 232 2 1 1 Instrument type
465 233 2 1 1 Report type
Preceding Radiosonde Station Report Category 1 Data (Standard Levels):
17 successive levels from 1000 mb of the following information:
starting byte = 466 + 14 x (level-1) + starting byte
integer position = 233 +7(level- 1) + integer location
xx = 01 to 17

1

 n/a 2 1 1 Geopotential height (m)
3 n/a 2 1 10 Temperature (C)
5 n/a 2 1 10 Dewpoint depression (C)
7 n/a 2 1 1 Wind direction (degrees)
9 n/a 2 1 1 Wind speed (knots)
11 n/a 1 1 1 Geopotential height QC flag
12 n/a 1 1 1 NCEP temperature QC flag
13 n/a 1 1 1 NCEP dewpoint QC flag
14 n/a 1 1 1 NCEP wind QC flag
Preceding Radiosonde Station Report Category 2 Data (Significant Levels):
705 353 2 1 1 Number of significant levels
50 successive levels from the surface of the following information:
starting byte = 706 + 10 x (level-1) + starting byte
integer position = 353 + 5 x (level-1) + integer location
xx = 01 to 50
1 1 2 1 10 Pressure (mb)
3 2 2 1 10 Temperature (C)
5 3 2 1 10 Dewpoint depression (C)
7 n/a 1 1 1 NCEP Pressure QC flag
8 n/a 1 1 1 NCEP temperature QC flag
9 n/a 1 1 1 NCEP dewpoint QC flag
10 n/a 1 1 1 Spare flag
Preceding Radiosonde Station Report Category 3 Data (Winds):
1,207 604 2 1 1 Number of significant wind levels
25 successive levels from the surface of the following information:
starting byte = 1,208 + 8 x (level -1) + starting byte
integer position = 604 + 4 x (level-1) + integer location
xx = 01 to 25
1 1 2 1 10 Pressure (mb)
3 2 2 1 1 Wind direction (degrees)
5 3 2 1 1 Wind speed (knots)
7 n/a 1 1 1 NCEP pressure QC flag
8 n/a 1 1 1 NCEP wind QC flag
Preceding Radiosonde Station Report Category 5 Data (Tropopause):
2 levels of the following information:
starting byte = 1,408 +14 x (level - 1) + starting byte
integer position = 704 + 7 x (level-1) + integer location
xx = 01 to 02
1 1 2 1 10 Pressure (mb)
3 2 2 1 10 Temperature (C)
5 3 2 1 10 Dewpoint depression (C)
7 4 2 1 1 Wind direction (degrees)
9 5 2 1 1 Wind speed (knots)
11 n/a 1 1 1 NCEP pressure QC flag
12 n/a 1 1 1 NCEP temperature QC flag
13 n/a 1 1 1 NCEP dewpoint depression QC flag
14 n/a 1 1 1 NCEP wind QC flag
Reconstructed Profile Flags for Preceding Radiosonde:
1,437 n/a 151 1 1 Reconstructed RAOB report flags
1,452 n/a 3 1 1 Matchup usefulness flags
1,455 n/a 1 1 1 Surface inversion
1,456 n/a 1 1 1 Terrain type
1,457 n/a 1 1 1 Co-location time window
1,458 n/a 3 1 1 Reserved for future use
Succeeding Radiosonde Station Report:
1,461 n/a 6 1 1 Radiosonde station ID
1,467 n/a 2 3 1 Day of synoptic report (see Note 4)
1,473 n/a 2 3 1 Balloon release date (see Note 5)
1,479 740 2 1 100 Observation time in hours (UTC)
1,481 741 2 1 128 Latitude (-90 to 90 degrees)
1,483 742 2 1 128 Longitude (-180 to 180 degrees)
1,485 743 2 1 1 Station elevation (m)
1,487 744 2 1 1 Instrument type
1,489 745 2 1 1 Report type
Succeeding Radiosonde Station Report Category 1 Data (Standard Levels):
17 successive levels from 1000 mb of the following information:
starting byte = 1,490 + 14 x (level-1) + starting byte
integer position = 745 + 7 x (level-1) + integer location
xx = 01 to 17
1 1 2 1 1 Geopotential height (m)
3 2 2 1 10 Temperature (C)
5 3 2 1 10 Dewpoint depression (C)
7 4 2 1 1 Wind direction (degrees)
9 5 2 1 1 Wind speed (knots)
11 n/a 1 1 1 Geopotential height QC flag
12 n/a 1 1 1 NCEP temperature QC flag
13 n/a 1 1 1 NCEP dewpoint QC flag
14 n/a 1 1 1 NCEP wind QC flag
Succeeding Radiosonde Station Report Category 2 Data (Significant Levels):
1,729 865 2 1 1 Number of significant levels
50 successive levels from the surface of the following information:
starting byte = 1,730 + 10 x (level-1) + starting byte
integer position = 865 + 5 x (level-1) + integer location
xx = 01 to 50
1 1 2 1 10 Pressure (mb)
3 2 2 1 10 Temperature (C)
5 3 2 1 10 Dewpoint depression (C)
7 n/a 1 1 1 NCEP pressure QC flag
8 n/a 1 1 1 NCEP temperature QC flag
9 n/a 1 1 1 NCEP dewpoint QC flag
10 n/a 1 1 1 Spare flag
Succeeding Radiosonde Station Report Category 3 Data (Winds):
2,231 1,116 2 1 1 Number of significant wind levels
25 successive levels from the surface of the following information:
starting byte = 2,232 + 8 x (level-1) + starting byte
integer position = 1,116 + 4 x (level-1) + integer location
xx = 01 to 25
1 1 2 1 10 Pressure (mb)
3 2 2 1 1 Wind direction (degrees)
5 3 2 1 1 Wind speed (knots)
7 n/a 1 1 1 NCEP pressure QC flag
8 n/a 1 1 1 NCEP wind QC flag
Succeeding Radiosonde Station Report Category 5 Data (Tropopause):
2 levels of the following information:
starting byte = 2,432 + 14 x (level-1) + starting byte
integer position = 1,216 + 7 x (level-1) + integer location
xx = 01 to 02
1 1 2 1 10 Pressure (mb)
3 2 2 1 10 Temperature (C)
5 3 2 1 10 Dewpoint depression (C)
7 4 2 1 1 Wind direction (degrees)
9 5 2 1 1 Wind speed (knots)
11 n/a 1 1 1 NCEP pressure QC flag
12 n/a 1 1 1 NCEP temperature QC flag
13 n/a 1 1 1 NCEP dewpoint depression QC flag
14 n/a 1 1 1 NCEP wind QC flag
Reconstructed Profile Flags for Succeeding Radiosonde:
2,461 n/a 15 1 1 Reconstructed RAOB report flags (see Note 6)
2,476 n/a 3 1 1 Matchup usefulness flags (see Note 6)
2,479 n/a 1 1 1 Surface inversion
2,480 n/a 1 1 1 Terrain type
2,481 n/a 1 1 1 Co-location time window
2,482 n/a 3 1 1 Reserved for future use
Notes:

1. YYMM DDHH mmss, where YY is the year, MM is the month, DD is the day, HH is the hour, mm is the minute, and ss is the number of seconds (UTC).

2. 0=good; 1=good, but redundant; 2=questionable; 3=bad; 4=experimental flag; 5= precipitating.

3. Mixing ratios are converted to their natural logs before being scaled.

4. The synoptic day for which the observation was made (YYMMDD).

5. The day that the balloon was actually released (YYMMDD). For observations at 0000z, the balloon is actually released at approximately 2330z. The balloon release time is frequently reported as the observation time, although the synoptic time is more commonly reported. In order to sort observations into chronological order, the balloon release date and time should be used.

6. Each byte represents a different flag, set to a character value "0" if FALSE and to the character value "1", if TRUE.

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