This data set includes calibrated brightness temperatures measured over Wakasa Bay in the Sea of Japan in January and February 2003. The MIR was carried on a military-type P-3 aircraft. Brightness temperatures were taken at 57 beam positions covering 100 degrees swath. These data were acquired in support of the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) Wakasa Bay Field Campaign. Data are available in binary format from NSIDC via FTP.
AMSR-E is a mission instrument launched aboard NASA's Aqua Satellite on 4 May 2002. The Wakasa Bay Field Campaign was designed to validate both AMSR and AMSR-E shallow rainfall and snowfall retrieval capabilities.
Wang, J. Millimeter-wave Imaging Radiometer (MIR) Brightness Temperatures, Wakasa Bay, Japan. Boulder, CO: National Snow and Ice Data Center. Digital media.
|Data format||Binary files|
|Spatial coverage and resolution||30° to 40°N, 130° to 150°E|
|Temporal coverage and resolution||14 January 2003 to 3 February 2003|
|File naming convention||Files use the convention "miryyddd.00n" where yy=year, ddd=day of year, n=1 or 2, indicating the file number for a given date.|
|File size||File sizes range from 1.3 to 15.9 MB.|
|Parameter(s)||Brightness temperatures (K).|
|Procedures for obtaining data||Data are available via FTP.|
NASA/Goddad Space Flight Center (GSFC)
NSIDC User Services
National Snow and Ice Data Center
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University of Colorado
Boulder, CO 80309-0449 USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
The data are stored in binary files. All values are in four-byte, little-endian IEEE floating point. Each logical record contains one calibrated MIR scan. Each logical record of size 2316 bytes (4 x 579) contains one calibrated MIR scan comprising temporal, spatial, and aircraft attitude information for the nadir position (beam position 29) of the scan, followed by a brightness temperature value for each of 57 beam positions at all seven MIR frequencies.
The file naming convention is "miryyddd.00n", where "yy" and "ddd" denote the year and Julian day the data was acquired. The "n" in the extension can be either 1 or 2; multiple files exist only if the processed data for a given day is larger than 15.8 MB. (Note: for 28 January, there is a file "mir03028.nad." During this flight, the MIR operated in a stare (non-scanning) mode for one segment of the flight. So the data file for this segment ends with ".nad" (nadir).)
File sizes range from 1.3 to 15.9 MB.
Southernmost Latitude: 30° N
Northernmost Latitude: 40° N
Westernmost Longitude: 130° E
Easternmost Longitude: 150° E
Selected dates between 14 January 2003 to 3 February 2003. The following table shows the dates for which data are available.
|Day of year||Date|
The parameter for these data is brightness temperatures.
The following table describes the format of the data.
|2||Month||Real time clock (RTC)|
|3||Day||Real time clock (RTC)|
|12||Longitude||Degrees (-West, +East)|
|13||Air Temperature||Degrees celsius|
|15||Pitch||Degrees (+ for nose down)|
|16||Roll||Degrees (+ for roll right)|
|18- 26||Housekeeping Temperatures|
|27||Hot average temperature for this scan|
|28||Cold average temperature for this scan|
|29||Hot temperature, 8-scan moving average|
|30||Cold temperature, 8-scan moving average|
|31- 39||Hot average counts for this scan|
|40- 48||Cold average counts for this scan|
|49- 57||Hot counts, 8-scan moving average|
|58- 66||Cold counts, 8-scan moving average|
|67-123||57 Brightness temperatures||Degrees Kelvin||89 GHz|
|124-180||Brightness temperatures||Degrees Kelvin||150|
|181-237||Brightness temperatures||Degrees Kelvin||183.3 +/-1|
|238-294||Brightness temperatures||Degrees Kelvin||183.3 +/-3|
|295-351||Brightness temperatures||Degrees Kelvin||183.3 +/-7|
|352-408||Brightness temperatures||Degrees Kelvin||220|
|466-522||Brightness temperatures||Degrees Kelvin||340|
The following figure shows brightness temperature (K) distribution measured on January 14, 2003 in the Sea of Japan for the seven MIR channels. The width of the images is about 14 km and the length is about 90 km. The dark blue areas (low brightness temperature) in the 150, 183±7, 220, and 340 GHz diagrams correspond to snowfall. The blue area in the 89 GHz diagram mostly reflects the ocean surface. The water vapor channels (183±a) strongly respond to water vapor below the aircraft.
A quicklook of the data sets acquired in the Wakasa Bay experiment indicates deterioration in the performance of the 183.3±3 GHz and 340 GHz channels in the latter part of the experiment.
Data are available via FTP.
Volume of data files is 180 MB.
View the data with an appropriate application. The investigators have provided a C routine for viewing these data. The routine is named "rdmir.c" and requires the "mir.h" file to run. Both files are included in the data directory.
The Millimeter-Wave Imaging Radiometer (MIR) is an airborne, total power, cross-track scanning radiometer that measures radiation at seven frequencies: 89, 150, 183.3±1, 183.3±3, 183.3±7, 220, and 340 GHz. Researchers can infer brightness temperatures, water vapor profiles, and cloud information from the data gathered by these frequencies. The sensor has a 3 dB beam width of 3.5 degrees at all frequencies. It can cover an angular swath up to ±50 degrees with respect to nadir. In every scan cycle of about 3 seconds, it views two external calibration targets in addition to the 100-degree scene scan; one of these targets is heated to a temperature of 330 K and another remains at the ambient temperature of the aircraft cruising altitude. The temperatures of these calibration targets are closely monitored to within ±0.1 K. The temperature sensitivity for all frequencies is on the order of 0.5 K and the calibration accuracy is about ±1 K in the brightness temperature range of 240-300 K. The measurement accuracy at the low end is less certain; based on the calibration studies in the laboratory, the accuracy near the liquid nitrogen temperature of 77 K is estimated to be ±3 K.
Wang, J. R. and L. A. Chang. 1990. Retrieval of water vapor profiles from microwave radiometric measurements near 90 and 183 GHz. J. Appl. Meteor. 29(10), 1005-1013.
Wang, J.R., S.H. Melfi, P. Racette, D.N. Whitemen, L.A. Chang, R.A. Ferrare, K.D. Evans and F.J. Schmidlin. 1995. Simultaneous measurements of atmospheric water vapor with MIR, Raman lidar and rawinsondes. J.Appl.Meteor. 34(7) 1595-1607,
Racette, P., R.F. Adler, A.J. Gasiewski, D.M. Jackson, J.R. Wang and D.S. Zacharias. 1996. An airborne millimeter-wave imaging radiometer for cloud, precipitation and water vapor studies. J. Atmos.Ocean.Tech. 13(3), 610-619,
The following acronyms and abbreviations are used in this document.
|AMSR-E||Advanced Microwave Scanning Radiometer - Earth Observing System|
|FTP||File Transfer Protocol|
|GSFC||Goddard Space Flight Center|
|MIR||Millimeter-wave Imaging Radiometer|