CAMEX-3 Multispectral Atmospheric Mapping Sensor (MAMS)
Table of contents
Instrument Description
MAMS is a multispectral scanner that measures reflected radiation from the Earth's surface and clouds in eight visible/near‑infrared bands, and thermal emission from the Earth's surface, clouds, and atmospheric constituents (primarily water vapor) in four infrared bands (Table 1). The 5.0 mRa aperture of MAMS produces an instantaneous field-of-view (IFOV) resolution of 100 m at nadir from the nominal ER-2 altitude of 20 km. The width of the entire cross path field‑of‑view scanned by the sensor is 37 km, thereby providing detailed resolution of atmospheric and surface features across the swath width and along the aircraft flight track. For clouds and thunderstorm features the IFOV decreases with increasing cloud height by a factor of (Z-20)/20, where Z is the cloud height in kilometers. Further details about MAMS may be found in Jedlovec et al. (1986, 1989) and Jedlovec and Atkinson (1993).
The split-window channels from MAMS are similar to those from the Advanced Very High Resolution Radiometer (AVHRR), VAS, and GOES I-M imager and sounder. The 11 mm channels of MAMS and VAS are very similar, while those of AVHRR and the GOES I-M imager and sounder are narrower and shifted toward shorter wavelengths. The 12 mm channel of AVHRR is positioned near 11.8 mm with a bandwidth about twice that of MAMS and VAS (which are centered at longer wavelengths). The GOES I-M imager and sounder 12 mm channels are also narrow when compared to AVHRR. One of the sounder 12 mm channels and the imager 12 mm channel are centered near 12.0 mm, while the other sounder channel is near 12.7 mm. These 12 mm channels measure upwelling radiation where water vapor and other constituent absorption (particularly, by the Q‑branch of CO2 at 12.63 mm) are more significant. The spectral differences of the 12 mm channels produce small differences in brghtness temperatures for VAS and MAMS, but somewhat larger differences between AVHRR and MAMS (or VAS).
Table 1. MAMS Channel Configuration for CAMEX-3
Visible Channels |
Wavelength |
1 |
0.42-0.45 |
2 |
0.45-0.52 |
3 |
0.52-0.60 |
4 |
0.60-0.67 |
5 |
0.63-0.73 |
6 |
0.69-0.83 |
7 |
0.76-0.99 |
8 |
0.83-1.05 |
IR Channels |
Wavelength |
9 |
6.54 |
10 |
6.54 |
11 |
11.12 |
12 |
12.56 |
Note: Channel 1 is used to store the least significant bits of the infrared channels. Channels 9 and 10 are redundant in wavelength but they have different sensitivities and dynamic ranges.
File Naming Conventions
Level 1B Data
The MAMS data provided has been exported from the Man-computer Interactive Data Access System (McIDAS) to a generic binary file. Each file represents a straight-line flight track (i.e., all turns have been eliminated due to difficulty in properly being able to acquire and navigate the data). For each straight line track, there are data for each channel (no visible channels [1-8] on nighttime missions), a latitude file, a longitude file, and ASCII header file, which provides some additional information not contained in the filename of the data. The filename is intended to provide metadata information about each file and is as follows:
- MAMS.YYYYMMDD.bHHMMSS.eHHMMSS.hLLLL.wEEE.cNN.Sb.type.Z
- where YYYY is the year, MM the month, and DD the day b, beginning time flag, e, ending time flag:
- HH the hour, MM the minutes, and SS the seconds corresponding to the beginning or ending time.
- h, height flag of the image in lines (LLLL), i.e., rows,
- w, width flag of the image in pixels (EEE), i.e., columns,
- c, channel flag: NN is the channel number (01-12)
- Note: cNN will be replaced by the words lat or lon for latitude/longitude files, or in the case of the ASCII header file --hdr will be used.
- S is the number of bytes (b) per data value (1, 2, or 4).
- type is the data format:
- bin for generic binary file, and
- asc for the ASCII header file.
- Z means the data file is Unix Compressed
In all cases the files are compressed using the Unix compress utility. To uncompress the files under Unix use uncompress [filename].
The data for the infrared channels (9-12) are calibrated brightness temperatures, while channels 1-8 are calibrated radiances. The latitude/longitude files are in decimal degrees of latitude and longitude. The ASCII header is a brief description of the file, which may provide additional information not found in the filename itself.
Browse Imagery
Browse Images will be provided as GIF images and will adhere to a similar naming convention as the level 1b data; however, certain unnecessary elements will be eliminated and/or replaced by appropriate substitutes. Examples:
MAMS.YYYYMMDD.bHHMMSS.eHHMMSS.VIS.browse.gif
for visible channels contained in a single GIF file and
MAMS.YYYYMMDD.bHHMMSS.eHHMMSS.IR.browse.gif
for infrared channels contained in a single GIF file.
For daytime flights there will be two sets (visible and infrared) for each leg of data. They will directly correspond to the raw data at the same time interval. Night flights have only IR imagery.
Data Format and Description
The files contain no header records and begin with the first line of data. Data files are integer 2 byte binary (scaled by 100) and the lat/lon files are 4 byte integers (scaled by 10000). The latitude/longitude files have a one-to-one correspondence with the data files, e.g., data element (4,5) will have its corresponding latitude and longitude in element (4,5) of the respective files.
Missing data values for calibrated radiances and brightness temperatures will be 0 (zero).
Example FORTRAN Read Routine
The program below is a stand-alone program called axread.f to read in data using the header record. The program was originally written on a Silicon Graphics workstation and may require minimal changes for other platforms.
C AXREAD - Read Data and Navigation Binary Files
C
C USAGE: AXREAD
C
C Data is stored as 2 dimensional arrays of binary fields whose dimensions
C are those of the original image lines/elements.
C
C An ASCII text file documents the format of the data files.
C It contains a listing for each of the data files.
C
C .hdr (header file) - This file contains ASCII text describing the image
C and the contents of the output data files.
C .cnn (data files) - These files contain binary data for a single
C calibration of a specific band (nn).
C .lat (latitude file) - Binary files each containing a 2 dimensional
C .lon (longitude file) array of latitudes or longitudes corresponding
C to the elements within the output data files.
C These files contain LAT/LON stored as integers
C (degrees*10000, 4 bytes per element).
C ----------
C
PARAMETER (MAXPIX = 716)
CHARACTER*80 CFILE, CLINE, CLAT, CLON, CNAV
C
INTEGER*2 BUFF2(MAXPIX)
INTEGER*4 BUFF4(MAXPIX)
LOGICAL DATA
C
C GET THE ASCII HEADER FILE NAME AND OPEN THE FILE
CALL GETARG (1, CFILE)
OPEN (10, FILE=CFILE, ERR=9999)
C
C READ THE ASCII HEADER FILE
NREC = 0
10 CONTINUE
READ (10, '(A)', ERR=9998, END=20) CLINE
PRINT *, CLINE
NREC = NREC + 1
C
C EXTRACT FILE INFORMATION
IF (NREC.EQ.17) THEN
READ (CLINE(37:43), '(I7)') NLINES
READ (CLINE(45:51), '(I7)') NELEMS
END IF
C
GO TO 10
C
20 CONTINUE
PRINT *
PRINT *, 'File Lines, Elements', NLINES, NELEMS
C
C --- READ THE DATA FILES
CFILE(43:) = 'cxx.2b.bin'
C
DO 301 NB=2,12
WRITE (CFILE(44:45), '(I2.2)') NB
C
C --- Check if Data for this Band
INQUIRE (FILE=CFILE, EXIST=DATA)
IF (.NOT.DATA) GO TO 301
PRINT *
PRINT *, CFILE
C
C --- open file
OPEN (30, FILE=CFILE, FORM='SYSTEM', ERR=301)
C
DO 300 K=1,5
READ (30) BUFF2
PRINT *, K, (BUFF2(I), I=1,5)
300 CONTINUE
C
CLOSE (30)
301 CONTINUE
C
C --- READ THE NAVIGATION FILES
CLAT = CFILE
CLON = CFILE
CLAT(43:) = 'lat.4b.bin'
CLON(43:) = 'lon.4b.bin'
PRINT *
PRINT *, 'Reading NAV files'
PRINT *, CLAT
PRINT *, CLON
C
OPEN (31, FILE=CLAT, FORM='SYSTEM', ERR=9991)
OPEN (32, FILE=CLON, FORM='SYSTEM', ERR=9991)
C
DO 900 K=1,5
READ (31) BUFF4
PRINT *, K, (BUFF4(I), I=1,5)
READ (32) BUFF4
PRINT *, K, (BUFF4(I), I=1,5)
900 CONTINUE
STOP
C
9990 continue
PRINT *, '--ERROR: Opening File for DATA'
STOP
C
9991 continue
PRINT *, '--ERROR: Opening File for NAV'
STOP
C
9998 CONTINUE
PRINT *, '--ERROR: Reading Header File'
STOP
C
9999 CONTINUE
PRINT *, '--ERROR: opening Header File'
END
C -------------------------------------------------------------
References
Jedlovec, G. J., W.P. Menzel, R.J. Atkinson, and G.S. Wilson, 1986: The Multispectral Atmospheric Mapping Sensor (MAMS): Instrument Description, Calibration, and Data Quality. NASA TM-86565, 37 pp.
Jedlovec, G. J., K. B. Batson, R. J. Atkinson, C. C. Moeller, W. P. Menzel, and M.W. James, 1989: Improved Capabilities of the Multispectral Atmospheric Mapping Sensor (MAMS). NASA TM-86565, 37 pp.
Jedlovec, G. J., R. J. Atkinson, 1993: Calibration, navigation, and registration of MAMS data for FIFE. NASA TM-108397, 49 pp.
Contact Information
To order these data or for further information, please contact:
Global Hydrology Resource Center
User Services
320 Sparkman Drive
Huntsville, AL 35805
Phone: 256-961-7932
E-mail: support-ghrc@earthdata.nasa.gov
Web: http://ghrc.nsstc.nasa.gov/
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