The DC-8 DADS data are available from the same site in subdirectory /dads. To obtain the data on tape, contact the DAAC User Services Office. ... BACKGROUND
TOGA COARE was a multidisciplinary, international research effort that investigated the scientific phenomena associated with the interaction between the atmosphere and the ocean in the warm pool region of the western Pacific. The field experiment phase of the program took place from 1 November 1992 through 28 February 1993 and involved the deployment of oceanographic ships and buoys, several ship and land based Doppler radars, multiple low and high-level aircraft equipped with Doppler radar and other airborne sensors, as well as a variety of surface-based instruments for in situ observations.
The NASA component of TOGA COARE, while contributing directly to overall COARE objectives, emphasized scientific objectives associated with the Tropical Rainfall Measuring Mission (TRMM) and NASA's cloud and radiation program.
INSTRUMENT INFORMATION
The AMMR radiometer package was flown onboard the DC-8 between 12 January to 24 February 1994 under the direction of Dr. Jim Wang of NASA Goddard Space Flight Center.
The AMMR measures thermal microwave emission (in degrees Kelvin of brightness temperature) from surface and atmosphere. For TOGA COARE, the AMMR (with frequencies between 10 and 100 GHz) was used for measurements of hydrometeors associated with tropical convective systems. Radiometers at 18, 21, 37 and 92 GHz are comparable to the frequencies on the Special Sensor for Microwave/Imager (SSM/I) onboard the Defense Meteorological Satellite Program (DMSP) satellite. Where aircraft flights coincided with SSM/I overpasses over the COARE domain, comparisons between satellite and AMMR sensors at different resolutions were proposed to study beam filling effect.
Instrument Geometry: The AMMR package is made up of AMMR-1 and AMMR-2. AMMR-1 consist of single-beam, microwave radiometers operating at 18.7, 18.7, 21 and 37 GHz, all viewing through a nadir port of the aircraft, with an incidence angle of 0 when the aircraft was on level flight. The two channels at 18.7 GHz should see the same scene and brightness.
AMMR-2 also consists of single-beam, microwave radiometers operating at 10, 21, 37 and 92 GHz. These radiometers were installed in the left windows of the DC-8 aircraft and viewed the scene at an incidence angle of 45 degrees in level flight.
Principles of Operation: The 37 and 92 GHz radiometers were dual-polarized. Georgia Institute of Technology operated the 92 GHz radiometer and is responsible for the calibration of the data. The 92 GHz data will be included in this AMMR dataset when they are submitted to the GSFC DAAC.
The spatial resolution of the data is between 1.5 to 2 Km. The temporal sampling is 1 scan per second. Following are the key components of these sensor assemblies and their characteristics:
Inst Channel Sensitivity Beamwidth View loc & angle ----------------------------------------------------------------------- AMMR-1 18 GHz 0.5 K 6 Deg. Nadir 21/37 0.5 6 Nadir AMMR-2 37 0.5 6 Window(45deg),H,V-pol 92 1.0 2 Window(45deg),H,V-pol 21 1.0 6 window(45deg),H-pol 10 1.0 6 Window(45deg),H-pol
DATA
General Characteristics: The AMMR instruments were operational for all thirteen mission flights of the DC-8 during the TOGA COARE Campaign yielding twenty six ASCII data files (13 each for AMMR-1 and AMMR-2). The total data volume is 45 MB.
AMMR files are named Adddhhmm.AR1 (for AMMR-1) and Gdddhhmm.AR2 (for AMMR-2) where ddd is the Julian day, hh is the hour, and mm is the minute the instrument was turned on for the flight.
Data Format. There are 10 parameters in each file:
Scan number Month Day Hour Minute Second Brightness temperatures in degrees Kelvin at 18.7 GHz, 18.7 GHz, 21 GHz, and 37 GHz
Latitude, Longitude, altitude and aircraft attitude information are not present in these quick-look data files, but may be obtained from the DC-8 DADS dataset.
The AMMR data files are formatted as follows:
Sample of AMMR-1 Data File: scan# mm dd hr mm ss 18.7GHz 18.7GHz 21GHz 37GHz --------------------------------------------------------- 1 2 8 18 22 37 284.15 286.65 284.46 286.71 2 2 8 18 22 38 285.74 288.10 284.08 287.97
Sample of AMMR-2 Data File: scan# mm dd hr mm ss 10GHz 10GHz 37VGHz 37HGHz --------------------------------------------------------- 1 2 10 19 0 7 119.95 104.78 201.66 151.80 2 2 10 19 0 8 119.69 104.34 201.22 151.79
Description:
Access Airborne Multichannel Microwave Radiometer (AMMR) Measurements Taken Onboard the NASA DC-8 During the TOGA COARE Intensive Observing Period.
Dataset Title:
Airborne Multichannel Microwave Radiometer (AMMR) Measurements Taken Onboard the NASA DC-8 During the TOGA COARE Intensive Observing Period
Latitude Resolution:
1.5 Km - 2 Km
Longitude Resolution:
1.5 km - 2 Km
Horizontal Resolution Range:
1 km - < 10 km or approximately .01 degree - < .09 degree
Temporal Resolution:
1 scan per second
Temporal Resolution Range:
1 second - < 1 minute
NASA TOGA COARE Project Office, 1993: Mission Summary Reports, TOGA COARE. NASA Langley Research Center, Mail Stop 483, Hampton, VA 23666.
NASA TOGA COARE Project Office, 1994: NASA/TOGA COARE Science Data Workshop II Proceedings, Albuquerque, New Mexico, March 15-17, 1994, NASA Langley Research Center, Mail Stop 483, Hampton, VA 23666, 4 pp.
TOGA ... COARE International Project Office (TCIPO), 1992: TOGA COARE Operations Plan, Working Version September 1992. University Corporation for Atmospheric Research, Boulder, CO 80307, 138 pp.
TOGA COARE International Project Office (TCIPO), 1993: TOGA COARE Intensive Observing Period Operations Summary. University Corporation for Atmospheric Research, Boulder, CO 80307, 505 pp.
TOGA COARE International Project Office (TCIPO), 1994: Summary Report of the TOGA COARE International Data Workshop, Toulouse, France, 2 - 11 August 1994, University Corporation for Atmospheric Research, Boulder, CO, 80307, 170 pp.
Wang, J.R. and A. Chang, 1990: Retrieval of water vapor profiles from microwave radiometric measurements near 90 and 183 GHz. J. Appl. Meteor., 29(10), 1005-1013.
Webster, P.J., and R. Lukas, 1992: TOGA COARE: The Coupled Ocean- Atmosphere Response Experiment. Bull. Am. Meteorol. Soc. 73, 1377-1416.
World Climate Research Programme (WCRP), 1985: Scientific Plan for the TOGA Coupled Ocean-Atmosphere Response Experiment. WCRP Publications Series, No. 3 Addendum, World Meteorological Organization, Geneva, 96 pp.
