DATA SET: Millimeter Imaging Radiometer (MIR) IF YOU USE OUR DATA, PLEASE ACKNOWLEDGE: The production and distribution of this data set are being funded by NASA's Mission To Planet Earth Program. The data are not copyrighted, however, we request that when you publish data or results using these data please acknowledge as follows: "The authors would like to thank the Process Studies Program Office (Code SEP, NASA Headquarters) and the Distributed Active Archive Center (Code 902.2) at Goddard Space Flight Center, Greenbelt, MD 20771 for the production and distribution of these data, respectively. These activities were sponsored by NASA's Mission to Planet Earth Program." 1. GENERAL INFORMATION The MIR data set is part of the atmospheric measurements collected in the intensive observation period of the Tropical Ocean Global Atmosphere-Coupled Ocean Atmosphere Response Experiment (TOGA-COARE). Jim Wang/GSFC and Paul Racette/GSFC are co-investigators on this instrument. The MIR data are archived at the Goddard Distributed Active Archive Center (DAAC). TOGA-COARE is an international research program aimed at investigating the interactions between the atmosphere and ocean in the warm pool region of the Western Pacific. The field experiment of the program took place from November, 1992 through February, 1993. The field experiment involved the deployment of research vessels and buoys, ship- and land-based Doppler radars, multiple low- and high- level aircraft equipped with various types of airborne sensors, as well as a variety of surface based and satellite coverage. The MIR was part of the NASA component of TOGA-COARE. The NASA component, while contributing to the overall COARE objectives, emphasized the scientific objectives associated with the Tropical Rainfall Measuring Mission (TRMM) and NASA's cloud and radiation research programs. 2. INSTRUMENT INFORMATION 2.1 Instrument Science Objectives MIR was flown on the NASA ER-2 from January 12 through February 24, 1993. The overall measurement objectives of the MIR include the evaluation of millimeter wavelengths for the detection and estimation of convective rainfall, and the study of the effects of cloud microphysical structures on rainfall estimation and water vapor profiles. The collected data will be useful in developing algorithms for interpreting data collected from future spaceborne microwave sensors such as Advanced Microwave Sensor Unit (AMSU) that will be flown onboard the EOS PM satellite. 2.2 Principals of Operation The following table summarizes some characteristics of the MIR radiometer: Channel Bandwidth Temporal Res. Beamwidth ----------------------------------------------------------------- 89 GHz 1.0 GHz <0.2 3.5 Deg. 150 1.0 <0.2 3.5 220 3.0 <0.3 3.5 184 1.0 <0.4 3.5 186 2.0 <0.3 3.5 190 2.0 <0.5 3.5 2.1.2 Instrument Geometry The instrument scanned in a plane perpendicular to the direction of flight with a swath of +/- 50 degrees from nadir. Each scan took 3 seconds. The table below summarizes some instrument characteristics. 3. DATA ORGANIZATION 3.1 General Characteristics The total volume of the MIR data set is ~148 MB. There are 12 MIR data files, each containing data from one mission flight of the NASA ER-2. These files have a typical size of ~12.5 MB. The file naming convention is: toga_flightXX.mir where XX is a 2-digit flight number MIR data consist of brightness temperatures in degrees Kelvin at 89, 150, 183.3+/-1, 183.3+/-3, 183.3+/-7 and 220 GHz. There are 12 binary data files, each containing data from one flight. The files are named "toga_flightXX.mir" where XX is a 2-digit flight number. They have been combined in a tar file and compressed with UNIX' "compress" utility. The data are in IEEE 32-bit (floating point) words. Each logical record has 359 words. The blocking factor is 20 and hence each physical record has 28720 bytes (20 x 4 x 359). 3.1.1 Flight coordination table. The following table relates MIR filenames to ER-2 and DC-8 flight numbers and dates for the 13 mission flights of the NASA/TOGA COARE campaign. Also included is ER-2 flight 93-061 of February 7, which produced MIR data although it is not designated as a mission flight. Date(UTC) ER-2 Flight DC-8 Flight MIR Filename ----------------------------------------------------------------- Jan 11-12 93-053 93-01-06 toga_flight01.mir Jan 17-18 93-054 93-01-07 toga_flight02.mir Jan 18-19 93-055 93-01-08 toga_flight03.mir Jan 25-26 93-056 93-01-09 toga_flight04.mir jan 31-Feb 1 93-058 93-01-10 toga_flight05.mir Feb 4 93-060 93-01-11 toga_flight06.mir Feb 6 93-01-12 Feb 7 93-061 toga_flight07.mir Feb 8-9 93-062 93-01-13 toga_flight08.mir Feb 10-11 93-063 93-01-14 toga_flight09.mir Feb 17-18 93-01-15 Feb 20-21 93-065 93-01-16 toga_flight10.mir Feb 22-23 93-066 93-01-17 toga_flight11.mir Feb 23-24 93-067 93-01-18 toga_flight12.mir 3.2 Data Format The following table summarizes the content of each logical record. Logical Record Format --------------------- Word 1 Record Number 2 Month - Real time clock (RTC) 3 Day - Real time clock (RTC) 4 Hour - IRIG 5 Minute - IRIG 6 Second - IRIG 7 Julian Day - Navigation 8 Hour - Navigation 9 Minute - Navigation 10 Second - Navigation 11 Latitude - Degrees 12 Longitude - Degrees (-West, +East) 13 Air Temperature - Degrees celsius 14 Altitude - Feet 15 Pitch - Degrees (+ for nose down) 16 Roll - Degrees (+ for roll right) 17 Heading - Degrees 18- 74 57 brightness temperatures - degrees Kelvin 90 GHz 75-131 " " " - " " 150 132-188 " " " - " " 183.3 +/-1 189-245 " " " - " " 183.3 +/-3 246-302 " " " - " " 183.3 +/-7 303-359 " " " - " " 220 4. DATA ACCESS 4.1 Data Access via FTP Data may be accessed on the Goddard DAAC public FTP area as follows: o ftp daac.gsfc.nasa.gov o login - anonymous o password - your Internet address o cd pub/toga_coare/aircraft/nasa_er2/mir You may then retrieve them using FTP's "mget" (for multiple files--wild cards allowed) or "get" command: get mir.tar 4.2 To Order Data on Tape Please call TOGA COARE user support to order MIR data on tape (see Section 6: Points of Contact). 4.2.1 Data are available on 4 mm (DAT), high or low density 8 mm (Exabyte), and 6250 Bpi 9-track tapes. Tapes are created with UNIX utilities "dd" and "tar" on a Silicon Graphics 440 system. The no-swap device and a block size of 63.5 KB are used. Tapes may be requested in "dd" or "tar" file format. By default the data are archived and distributed in compressed format; however, they are available in uncompressed format by special request. Each tape distributed by the Goddard DAAC contains printed paper labels with the names of the files it contains in the order they were written. Files are compressed using the standard UNIX "compress", indicated by a ".Z" appended to the data file name, and should be uncompressed using the UNIX "uncompress" command. The same utility that was used to create the tape, "dd" or "tar", must be used to access the data. If compressed files are requested, the data are compressed before the "dd" or "tar" utility is executed. Therefore, compressed data should be uncompressed after copying it from tape to local disk. Data on magnetic tape are written in either standard UNIX "tar" or "dd" format on an SGI computer. The tape block size is 63.5 KB, which translates to a blocking factor of 127. To read a "tar" format tape on a computer with a UNIX operating system, use the command: tar xvfb 127 where xvbf are tar command key arguments: x indicates that the data are to be read form tape v requests verbose output, i.e., processed file names will be listed b states that a blocking factor is specified f states that an archive name is specified 127 is the blocking factor The fields in < > are system specific and may specify a device such as a tape drive, or it may spacify a file directory, etc. The specific parameters are dependent upon your local workstation configuration (e.g., this will be /dev/8mm1nr if you were to read the tape off the 8mm1 tape drive on the DAAC computer and the nr specifies the no rewind option). To read a tar format tape on a VAX computer with a VMS operating system, you will need vmstar public domain software. Use the command: mount /FOREIGN/RECORD=3D512/BLOCK=3D10240 vmstar xvf =20 Note that the tape should be written with a blocking factor of 20 in order to translate to a block size of 10 KB that vmstar can read. As mentioned above, the default block size used by the DAAC in writing data to tape is 63.5 KB. Therefore, please notify the DAAC if a tape is going to be read with a VAX VMS workstation. To read a "dd" format tape on a computer with a UNIX operating system, use the command: dd if=3D of=3D bs=3D65024 where: if=3D specifies the tape drive with "no rewind option" of=3D specifies the desired output file name bs=3D65024 indicates the block size in bytes=20 To read "dd" format tapes on a VAX computer with a VMS operating system, simply use the "copy" command. A public domain software, lzw, is available to read UNIX compressed data format on VAX VMS. To read compressed data files, you must first use "vmstar" or the "copy" command to unload the data from tape. Then issue the "lzw" command. 5. DATA QUALITY ASSESSMENT The data are geo-referenced (including altitude) based on the ER-2's Inertial Navigation System (INS). The noise threshold for the MIR is 1 degree Kelvin. Noise saturation did not occur during the TOGA-COARE campaign. Absolute calibration is performed every scan cycle by consecutively pointing the scan mirror at the hot (330 K) and cold (ambient air cooled) external calibration loads. 6. POINTS OF CONTACT For NASA/TOGA COARE user support, please contact: Pat Hrubiak EOS Distributed Active Archive Center(DAAC) Code 902.2 NASA Goddard Space Flight Center Greenbelt, Maryland 20771 Internet: hrubiak@daac.gsfc.nasa.gov (301) 286-1381 (voice) (301) 286-1775 (FAX) For detailed information about the sensor or data, please contact: Principal Investigator: James R. Wang Code 975 NASA Goddard Space Flight Center Greenbelt, MD 20771 Internet: wang@sensor.gsfc.nasa.gov (301) 286-8949 (voice) (301) 286-1761 (FAX) Co-Investigator: Paul Racette Code 975 NASA Goddard Space Flight Center Greenbelt, MD 20771 Internet: per@meneg.gsfc.nasa.gov (301) 286-9114 (voice) (301) 286-1762 (FAX) To examine the Goddard DAAC's data holdings, please access the DAAC Information Management System (IMS) as follows: telnet daac.gsfc.nasa.gov login: daacims password: gsfcdaac or contact the DAAC User Services Office (Phone: 301-286-3209, Fax: 301-286-1775, Email: daacuso.@eosdata.gsfc.nasa.gov). 7. DATA STATUS/PLAN The MIR data first became available on DAAC public FTP in April 1994. Please see other subdirectories of the FTP directory "toga-coare" for other TOGA-COARE data sets. After a 12 month validation period, data will be migrated to the Goddard DAAC's main archive. Other DAAC data holdings in the archive can be accessed as follows through the DAAC IMS, a menu-driven user interface with online help: telnet daac.gsfc.nasa.gov login: daacims password: gsfcdaac or contact the DAAC User Services Office (Phone: 301-286-3209, Fax: 301-286-1775, Email: daacuso.@eosdata.gsfc.nasa.gov). 8. REFERENCES 8.1 Instrument/Data Processing Documentation NASA/TOGA COARE Science Data Workshop II Proceedings, March 15-17, 1994, p 4, FIRE Project Office, NASA Langley Research Center, Mail Stop 483, Hampton, VA 23666. 8.2 Journal Articles and Study Reports Falcone, V. J., M., K. Griffin, R. G. Isaacs, J. D. Pickle, J. F. Morrissey, A. J. Jackson, A. Bussey, R. Kakar, J. Wang, P. Racette, D. J. Boucher, B. H. Thomas, and A. M. Kishi, 1993: SSM/T-2 calibration and validation data analysis. Environ. Res. Papers, No. 1111, PL-TR-92-2293, Phillips Laboratory, Hanscom Air Force Base, MA 01731-5000. Racette, P., L. R. Dod, J. C. Shiue, R. F. Adler, D. M. Jackson, A. J. Gasiewski, and D. S. Zacharias, 1992: Millimeter-wave imaging radiometer for cloud, precipitation, and atmospheric water vapor studies. IGARSS'92, Houston, Texas, 1426-1428. --------- 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. Whiteman, R. A. Kakar, R. A. Ferrare, K. D. Evans and F. J. Schmidlin, 1993: Simultaneous measurements of atmospheric water vapor with MIR, Raman Lidar and rawinsondes. IGARSS'93. ---------