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MIT RADAR DATA AND PRODUCTSS. Rutledge (Colorado State University, USA)Announced availability: 1 April 1994 Data AccessThe following MIT radar data and products are available:
BackgroundTwo Doppler radars, stabilized in order to obtain rainfall statistics and single-Doppler velocity measurements, were operated during TOGA COARE. The Massachusetts Institute of Technology's 5-cm radar was deployed on board the U.S. research ship John V. Vickers, a 220' refurbished tuna vessel, owned by the University of Southern California and operated by the NOAA Corps through 1993. During TOGA COARE, the research vessel was, with the exception of a couple of days, stationed in the center of the IFA at 2S, 156 15'E from 2 November 1992 through 23 February 1993. The NOAA/TOGA radar, also a 5-cm system, was deployed on board the People's Republic of China research vessel Xiangyanghong #5 (aka PRC-5), stationed near 2S, 154E from 5 November 1992 to 19 February 1993.The MIT WR73 C-band operates near the 5 cm wavelength band with an 8U dish (1.5 degree beamwidth), which provides a reasonable tradeoff between maximum range and sensitivity and which is only weakly attenuated by intervening rainfall. The transmitter is permanently mounted in an easily-transportable shipping 'sea-tainer'. During TOGA COARE, stabilization of the relatively small antenna (8-12') of the MIT and TOGA radar were required. Stabilization was effected by an Inertial Navigation Unit which measured ship roll, pitch and yaw, and modified in real time the actual antenna servo commands (thus, while precise PPI cones were scanned in earth-relative coordinates, 'wavy' conical scanning commands were issued to the antenna to balance ship motion). The signal processing and antenna control hardware, as well as the data ingestion and analysis software, are from SIGMET, Inc.
Technical specifications
The Radar Meteorology group at Colorado State University is home to the TOGA COARE CSU/MIT Radar archive, while NASA/GSFC is responsible for the COARE TOGA radar data.
Data File Information1. SIGMET IRIS Raw DataOnly a small portion of the raw SIGMET IRIS data is made available at any one time via anonymous FTP by Colorado State University. Users need to request that the data be placed on disk by sending a message to datareq@olympic.atmos.colostate.edu. Files will then be placed in a sub-directory named with the month and day. For example, the data files from 27 November will be in the sub-directory coare/raw-iris/1127. The data file name is constructed from the radar name and first date/time on the volume. As an example, the data file for the volume for 08:40Z on 27 November 1992, is called coare/raw-iris/1127/MIT_921127_0838.iris/. Before requesting data, users should read the description of the archive and look at the tape catalogs of the data.The full set of SIGMET IRIS raw data is available upon request from either the National Center for Atmospheric Research (NCAR) by contacting Dennis Joseph or from the NASA/GSFC DAAC by contacting Pat Hrubiak. At NASA, native data are written three days to a cartride and average 800-900 MB per cartridge. Data are available on 8mm tape. The total ship radar datast is about 45GB. To extract files off the tape use the following commands: cp TapeDeviceFileName DiskFileNameWith a Solaris 2.3 OS you might do something like this mt -f /dev/rmt/0ln fsf 20 # position tape cp /dev/rmt/0ln /usr/name/data/MIT_921010_2311.iris # copy file )The DiskFileName is determined by the user. Please check catalog or inventory files (see below) to determine the tape and the location of the file on tape for a certain time.
2. Universal Format Reprocessed Radar DataNASA/GSFC DAAC provides subsets and the full set of already reformatted radar data to Universal Format. To obtain the dataset, contact Pat Hrubiak.
3. Radar Tape CatalogThe catalog files provide a comprehensive review of several engineering and meteorological parameters associated with each task performed and recorded by the radar (the word "task" is used by the SIGMET to describe a scanning sequence; e.g., TC_NEAR, RAIN).The `catalogs' directory at CSU (radarmet.atmos.colostate.edu, subdirectory coare/catalogs) named for the radar (RAD) which collected the data (either MIT or TOG) and the date/time of the first volume on the data tape. For example, the file named MIT_921127_0701.cat holds the information for radar volumes on the data tape whose first volume was recorded by the MIT radar starting at 07:01Z on 27 November 1992. The catalog listing for a single volume holds the volume identification plus information for each individual scan. As an example, the following is the entry for the 29th volume on the data tape cataloged in MIT_921127_0701.cat.
Volume 29 1992.11.27 MIT-CSU MIT-CSU
PRF: 1000 Gate spacing: 125m 1 gates Nyquist: 13.4m/s
scan type dir time azimuth range elev range fixed # rays
1 RHI DN 08:38:12-08:38:24 324.9-325.1 20.1- 0.1 325.0 94
2 RHI UP 08:38:26-08:38:40 327.9-328.1 -0.1- 19.9 328.0 99
3 RHI DN 08:38:43-08:38:55 330.9-331.1 20.1- 0.1 331.0 93
4 RHI UP 08:38:58-08:39:11 333.9-334.1 -0.1- 20.0 334.0 100
5 RHI DN 08:39:13-08:39:25 336.9-337.1 20.1- 0.1 337.0 94
6 RHI UP 08:39:28-08:39:42 339.9-340.1 -0.1- 20.0 340.0 97
7 RHI DN 08:39:44-08:39:56 342.9-343.1 19.9- 0.1 343.0 93
8 RHI UP 08:40:00-08:40:05 345.9-346.1 -0.1- 7.4 346.0 38
The first line gives the volume number and date for the radar volume. The second
line gives the pulse repetition factor, the spacing between successive gates in
a ray, the number of gates in a ray (always 1, for complicated reasons), and the
Nyquist velocity. Each numbered line refers to a single sweep in the volume,
giving the sweep number, the scan type (PPI vs RHI), the ranges for the time,
azimuth angle, and elevation angle, the programmed fixed angle, and the number
of rays.
At the NASA/TRMM site, the directories are named according to the ship and the On-Station Period (OSP) or "cruise". Each ship had three separate cruises of about 30 days, with breaks in between, during which time the ships were approaching, at, or leaving Honiara, Guadalcanal in the Solomon Islands. Directory naming convention:
sss_crN_catalogs, where
ssss = "prc5" (TOGA radar) or "vick" (MIT radar)
N = Cruise
The catalogs were produced by running through each tape in the tape archive. The
original tapes consisted of approximately one day of radar data, (usually from
0300 one day to 0300 the next). These catalogs were produced from 1:3 copies of
the original data (ie, ~3 days/tape).
Catalog file naming convention:
SSSmmddyy_hhmmss.cat
where,
SSS = "PRC" (TOGA radar) or "VIC" (MIT radar)
yymmdd = date of first scan on tape
hhmmss = time of first scan on tape
4. Radar Tape InventoriesRadar tape inventories are available from CSU via anonymous FTP from radarmet.atmos.colostate.edu in subdirectory coare/inventory.Example: Inventory of Tape MIT_92_07_18_P3Y 20-MAR-1993 23:48:52.53 There are 163 inventoried product files on this tape 1 RAW LOWLEVEL 1769Kb 40km Z V W 18:10 18 JUL 92 LOWLEVEL 2 RAW LONGRANGE 129Kb 256km Z V W 18:15 18 JUL 92 LONGRANGE 3 RAW LOWLEVEL 2015Kb 40km Z V W 18:20 18 JUL 92 LOWLEVEL 4 RAW VOLUME_FAR 866Kb 50km Z V W 18:25 18 JUL 92 VOLUME_FAR 5 RAW LOWLEVEL 2125Kb 40km Z V W 18:30 18 JUL 92 LOWLEVEL 6 RAW LONGRANGE 141Kb 256km Z V W 18:35 18 JUL 92 LONGRANGE 7 RAW VOLUME_FAR 368Kb 50km Z V W 18:40 18 JUL 92 VOLUME_FAR 8 RAW SCIENTIFIC1 356Kb 50km Z V W 18:43 18 JUL 92 SCIENTIFIC1At NASA, inventories are set up as follows: ___________________________R/V Vickers #5 Cruise #1__________________________ _____________________________________________________________________________ Tape Name Catalog Name First Scan Last Scan #Files #Blks VICK_cr1_tape01 VIC921105_2254 11/05/92@22:54 11/06/92@20:01 327 27928 VICK_cr1_tape02 VIC921110_1030 11/10/92@10:30 11/14/92@02:31 1160 139768 VICK_cr1_tape03 VIC921114_0311 11/14/92@03:11 11/14/92@12:38 158 10652 VICK_cr1_tape04 VIC921116_2040 11/16/92@20:40 11/19/92@00:55 745 64303 VICK_cr1_tape05 VIC921119_0040 11/19/92@00:40 11/22/92@03:41 942 68394 VICK_cr1_tape06 VIC921122_0350 11/22/92@03:50 11/25/92@04:00 1082 189591 VICK_cr1_tape07 VIC921125_0401 11/25/92@04:01 11/29/92@04:21 1299 128373 VICK_cr1_tape08 VIC921129_0430 11/29/92@04:30 12/02/92@04:20 841 68545 VICK_cr1_tape09 VIC921202_0421 12/02/92@04:21 12/06/92@03:50 1242 111771 VICK_cr1_tape10 VIC921206_0351 12/06/92@03:51 12/09/92@04:10 1016 102392 VICK_cr1_tape11 VIC921209_0412 12/09/92@04:12 12/13/92@06:00 639 72087 5. Radar Base-ScansTo help select the proper time period, base-scan images taken every ten minutes from the MIT radar are available. They have been averaged onto a 400 km by 400 km grid with 2 km grid point spacing. The reflectivity of any gate within 4.5 km of a grid point was averaged into that grid point. The image files use the more-or-less standard GIF format. Like the data files, these subdirectories are named by the month and day. Thus the image file for 08:40Z on 27 November 1992 is called:
COARE/base-scans/gif/1127/MIT_921127_0840.gif
A color videotape showing the base-scans from the MIT radar is available upon
request from the TCIPO. The video covers all three Vickers cruises and a total
time of three months. The videotape can speed up this time so that three months
pass in under 25 minutes. The radar images display the radar reflectivity in
colored bands, overlaid with the date and time, range rings, and azimuth lines.
As for the technical details, the radar data were interpolated onto a fixed grid with an origin fixed to the earth's surface (not the ship). The value at each grid point was calculated by averaging all data gates with 4.5 km. The grid itself is centered at 2 5'S, 156 15'E and covers a 500 km by 500 km square grid with 2.5 km grid point spacing (not 2 km as mentioned in the prespan of the actual video). The data were taken only from the rainfall TRMM scans, which were run every ten minutes during the cruises. If no such scan existed near the desired 10-min mark, a blank image was inserted in the videotape. Thus one frame was generated every 10 min, and the videotape was recorded at a rate of 10 frames per second.
6. Radar Data SoftwareTo faciliate the processing of the data, SIGMET IRIS raw data can be converted to Universal Format by using nsig2uf. Nsig2uf information, binaries, and source code can be obtained from http://trmm-fc.gsfc.nasa.gov/trmm_gv/software/conversion/nsig2uf.html(e.g. nsig2uf -i MIT_921010_2311.iris -o MIT_921010_2311.uf ) CSU offers several programs that can be used for data conversion and processing. The programs are located in subdirectory scott.
7. Position DataVickers position data are available via anonymous FTP from http://trmm-fc.gsfc.nasa.gov/trmm_gv/field_campaigns/toga_coare/radar/radar.html.
For more information and/or to obtain a copy of the tape, please contact:
Steve Rutledge
email: rutledge@olympic.atmos.colostate.edu or
Paul Hein
email: hein@olympic.atmos.colostate.edu
Return to Ship Data Overview Return to TOGA COARE Data User's Guide Table of Contents Return to the COARE Homepage http://www.ncdc.noaa.gov/oa/coare/catalog/data/convection_mesoscale/mit_radar.html Downloaded Thursday, 08-Jan-2009 19:43:23 EST Last Updated Thursday, 26-May-2005 17:16:52 EDT Please see the NCDC Contact Page if you have questions or comments. |