Advanced Microwave Precipitation Radiometer (AMPR)
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| AMPR data on FTP |
Overview
The AMPR data set is part of the atmospheric measurements collected during the intensive observation period of the Tropical Ocean Global Atmosphere-Coupled Ocean Atmosphere Response Experiment (TOGA-COARE). The Principal Investigators on the AMPR instrument are Roy F. Spencer and Robbie E. Hood of NASA/Marshall Space Flight Center. This data is archived at the Goddard DAAC as part of the NASA TOGA COARE data set and at the Marshall Global Hydrology Resource Center as part of the AMPR data set.
The AMPR Instrument
Mission and ObjectivesThe Advanced Microwave Precipitation Radiometer (AMPR) remotely senses passive microwave signatures of geophysical parameters from an airborne platform. The instrument is a low noise system which can provide multifrequency microwave imagery with high spatial and temporal resolution. AMPR data are collected at a combination of frequencies (10.7, 19.35, 37.1, and 85.5 GHz) unique to current NASA aircraft instrumentation. These frequencies are well suited to the study of rain cloud systems, but are also useful to studies of various ocean and land surface processes.
The AMPR is a cross-track scanning total power microwave radiometer with four channels centered at 10.7, 19.35, 37.1 and 85.5 GHz. It has a dual lens antenna to accommodate two separate feedhorns. One horn that feeds the three higher frequency channels is a copy of the Special Sensor Microwave/Imager (SSM/I) spaceborne multifrequency feedhorn currently flying aboard the Defence Meteorological Satellite Program (DMSP) F8 and F10 satellites. The other AMPR feedhorn accommodates the 10.7 GHz frequency.
The following table lists AMPR performance characteristics:
85.5GHz 37.1GHz 19.35GHz 10.7GHz Bandwidth (MHz) 1400 900 240 100 Temp. Res. (deg C) 0.16 0.15 0.3 0.26 Integ. Time (ms) 50 50 50 50 Horn Type SSM/I SSM/I SSM/I GTRI Lens Diameter (inches) 5.3 5.3 5.3 9.7 Beamwidth (degrees) 1.8 4.2 8.0 8.0 Footprint(@20 km ER-2 alt.)(km) 0.6 1.5 2.8 2.8 Beam Efficiency (%) TBD 98.8 98.7 97.8 Cross Polarization (%) TBD 0.4 1.6 0.2 The AMPR radiometer is designed to fly in the Q-bay of a NASA ER-2, a compartment in the belly of the aircraft directly behind the pilot's cockpit. The dual antenna and scanning mirror extend below the aircraft body into a hatch opening. The instrument has a 90 degree total scan centered at nadir. The data footprints are contiguous at 85.5 GHz and coincident at all four channels leading to oversampling at the lower frequencies. Rotating polarization for all four channels is currently used during scanning. The polarization varies from vertical at 45 degrees to the left of nadir. At the nadir position, the polarizations are equally mixed. This scanning geometry allows dual-polarized information to be collected at the extreme scan angles with opposite aircraft passes over a given target.
The Data
Data Parameter Calibrated Brightness Temperatures in Degrees K Spatial Coverage -146 to -156lon, 0 to -21 lat Spatial Resolution Aircraft flight tracks Temporal Coverage Jan 11 1993 - February 24 1993 Temporal Resolution 11 eight-hour mission flights The following table relates AMPR data file names to ER-2 and DC-8 flight numbers and to the dates of the 13 mission flights of the NASA/TOGA COARE campaign. The objectives column is included for the convenience of the user; the mission objective was convection when it was forecast in the target area and radiation when it was not. Because of the length of the AMPR file names, only the unique portion of each file name (the Julian day) is listed in the table.
Date(UTC) ER-2 Flight DC-8 Flight AMPR File Objective Jan 11-12 93-053 93-01-06 011 Radiation Jan 17-18 93-054 93-01-07 017 Convection Jan 18-19 93-055 93-01-08 019 Convection Jan 25-26 93-056 93-01-09 025 Radiation jan 31-Feb 1 93-057 93-01-10 031 Radiation Feb 4 93-060 93-01-11 035 Convection Feb 6 93-01-12 Convection Feb 7 93-061 039 Feb 8-9 93-062 93-01-13 040 Convection Feb 10-11 93-063 93-01-14 041 Convection Feb 17-18 93-01-15 Convection Feb 20-21 93-065 93-01-16 051 Convection Feb 22-23 93-066 93-01-17 053 Convection Feb 23-24 93-067 93-01-18 054 Radiation Quality Assessment
Very good (based on user feedback)
Data Status and Plan
The AMPR data is part of the permanent NASA/TOGA COARE Archive at the Goddard DAAC. Please see other subdirectories of the FTP directory "toga_coare" for other TOGA COARE data sets.
The Files
The total volume of the AMPR data set, including browse products, is 111 MB. There are 12 AMPR data files, each containing data from one mission flight of the NASA ER-2. These files total 85 MB in volume and have a typical file size of ~7.5 MB. The files are named
amprtb93.XXX_toga_v023.dat where XXX is the Julian day on which the flight took off.
The AMPR data is in a binary native format. The "fixed INS" AMPR dataset structure (version 1; v1) is detailed in document "amprdata.format.v1" which resides in directory ampr.
An AMPR data file consists of one record header followed by many data records.
Header (ALL ARE 4-BYTE WORDS):
4-BYTEword Term Definition/example ---------- ---- ------------------ 1 Julian start date (yyddd; e.g. 93035) 2 Julian start time (hhmmss: e.g. 182516) 3 Number of data lines (e.g. 9038 data scans to follow) 4 Number of elements/line (should always be 410) 5 Number of bytes/element (should always be 2; therefore 820 bytes of data per scan) One record (scan line) consists of: 2-BYTEword Term Definition/example ---------- ---- ------------------ 1 Year (yy; e.g. 91) 2 Julian Day (jjj; e.g. 143) 3 Hour (hh; e.g. 18 (=6 pm) 4 Minute and second (mmss; e.g. 3410) 5 Calibration or data scan (0=datascan, 1=calscan) 6 Scan number (1-based, starting at 1) 7 Latitude *100 (e.g. 3145 = 31.45 degN) 8 Longitude *100 (e.g. 8068 = 80.68 degW) 9 North/South velo. *10 (e.g. 1703= 170.3 knots-North) 10 East/West velocty *10 (e.g. 2455= 245.5 knots-East) 11 Aircraft heading *100 (-180 to +180 degs; e.g. 4500=45.00=NE) 12 Ground speed *10 (e.g. 4590= 459.0 knots) 13 Air Temperature *10 (e.g. 2452= 245.2 Kelvin) 14 Altitude (in thousands of feet) 15 Altitude (remaining feet; e.g.W14+W15=Alt.) 16 Air speed *10 (e.g. 5207= 520.7 knots) 17 Aircraft pitch *100 (e.g. 120 = 1.20 degs-nose down) 18 Aircraft roll *100 (e.g. 1567= 15.67 degs-right) 19-23 Power Monitor A(5) *10 (Counts; e.g. -103=-10.3) 24-27 Power Monitor B(4) *10 (Counts; " ) 28 Blank (e.g. 0) 29-35 Cold Thermistors(7) *10 (degrees K; e.g. 2458 = 245.8 K) 36-42 Warm Thermistors(7) *10 (degrees K; e.g. 3184 = 318.4 K) 43-62 10gHz warm radio(20)*10 (digital counts; e.g. 14425=1442.5 Dc's) 63-82 10ghz cold radio(20)*10 ( "" "" ) 83-102 19gHz warm radio(20)*10 103-122 19gHz cold radio(20)*10 123-142 37gHz warm radio(20)*10 143-162 37gHz cold radio(20)*10 163-182 85gHz warm radio(20)*10 183-202 85gHz cold radio(20)*10 203-206 Gain 10,19,37,85 *100 (e.g. 324 = 3.24 DC/K) 207-210 Noise 10,19,37,85 *1000 (e.g. 653 = .653 K) 211-260 10GHz Tb Data *10 | 261-310 19GHz Tb Data *10 |>(Calibrated Brightness Temperatures 311-360 37GHz Tb Data *10 | in degrees Kelvin) 361-410 85GHz Tb Data *10 |Software. Fortran 77 program ampr_read.f was provided by the data producer to read a binary AMPR data file into memory.
The AMPR data set includes two types of browse products:
The browse files total ~26 MB in volume and may be displayed with any GIF viewer.
- calibrated brightness temperatures in GIF format
- flight tracks for the NASA-ER2 mission flights in GIF format
Calibrated Brightness Temperature Images. Browse images in GIF format were generated from data segments that were deemed noteworthy by the AMPR instrument team. A group was created for each mission flight of the ER-2 and they range in number from 22 to 27 per flight. The naming convention for these image files is:
amprbr93.XXX_toga_tb_brwsYY.gifwhere XXX is the Julian day on which the flight took off and YY is the sequence number of the image within that flight group.NASA ER-2 Mission Flight Track Images. Each image consists of an ER-2 mission flight track geolocated on a 2 degree x 2 degree grid.
The naming convention for these image files is:
amprft93.XXX_toga_track.gifwhere XXX is the Julian day on which the flight took off.
Data Access
FTP Access to AMPR Data
AMPR Calibrated Brightness Temperatures (Binary data files)
Points of Contact
- For information about or assistance in using any NASA/TOGA COARE data, contact
- GES DISC User Services
- Code 610.2
- NASA Goddard Space Flight Center
- Greenbelt, Maryland 20771
- GES DISC User Services
- 301 614-5224
- For detailed information about the sensor or data, please contact
- Principal Investigator:
- Roy Spencer
- NASA Marshall Space Flight Center
- Mail Stop ES43
- Huntsville, AL 35812
- (205) 544-1686 (Voice)
- (205) 544-5760 (fax)
- Co-Investigator:
- R. E. Hood
- NASA Marshall Space Flight Center
- Mail Stop ES43
- Huntsville, AL 35812
- Internet: Robbie.Hood@msfc.nasa.gov
- (205) 544-5407 (Voice)
- (205) 544-5760 (fax)
References
Instrument/Data Processing Documentation
NASA/TOGA COARE Science Data Workshop II, Proceedings of a workshop held in Albuquerque, New Mexico, March 15-17, 1994, July 1994, NASA TOGA COARE Project Office, NASA Langley Research Center, Mail Stop 483, Hampton, VA 23666.
ER-2 Flight Summary Report, NASA ER-2 Deployment, Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment, Aircraft Data Facility, NASA Ames Research Center, Mail Stop 240-6, Moffett Field, CA 94035-1000
Mission Summary Reports, TOGA COARE, November 1993, NASA TOGA COARE Project Office, NASA Langley Research Center, Mail Stop 483, Hampton, VA 23666
Journal Articles and Study Reports
Spencer, R.W., R.E. Hood, F.J. LaFontaine, E.A. Smith, R.Platt, J. Galliano, V.L. Griffin and E. Lobl, 1993: High resolution imaging of rain systems with the Advanced Microwave Precipitation Radiometer. J. Atmos. Oceanic Technol., 11, 849-857,
Turk, J., J. Vivekanandan, F.S. Marzano, R.E. Hood, R.W. Spencer, and F.J. LaFontaine,1994: Active and passive microwave remote sensing of precipitating storms during CaPE. Part I: Advanced Microwave Precipitation Radiometer and polarimetric radar measurements and models. Meteorology and Atmospheric Physics, Special Issue on Physical Retrievals of Hydrological Variables from Space-Based Microwave Instruments, v. 54 (1-4), p. 3-27, 1994.
Marzano, F.S., A. Mugnai, E.A. Smith, X. Xiang, J. Turk, and J. Vivekanandan, 1994: Active and passive remote sensing of precipitating storms during CaPE. Part II: Intercomparison of precipitation retrievals over land from AMPR radiometer and CP-2 radar. Meteorology and Atmospheric Physics, Special Issue on Physical Retrievals of Hydrological Variables from Space-Based Microwave Instruments v. 54 (1-4), p. 29-51, 1994.
Vivekanandan, J., J. Turk, and V.N. Bringi, 1993: Comparisons of precipitation measurements by the Advanced Microwave Precipitation Radiometer and multiparameter radar. IEEE Trans. on Geosci. and Remote Sens., 31, No. 4, 800- 870.
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