Airborne Multichannel Microwave Radiometer (AMMR) Measurements Taken Onboard the NASA DC-8 During the TOGA COARE Intensive Observing PeriodEntry ID: COARE_cm_dc8.ammr
Abstract: The NASA/TOGA COARE Data Archive
The AMMR data are available from the NASA GSFC DAAC via ftp at
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
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.
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
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:
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
Data Set Citation
Dataset Originator/Creator: TOGA COARE
Dataset Title: Airborne Multichannel Microwave Radiometer (AMMR) Measurements Taken Onboard the NASA DC-8 During the TOGA COARE Intensive Observing PeriodOnline Resource: http://daac.gsfc.nasa.gov/fieldexp/TOGA/
Start Date: 1993-01-01Stop Date: 1993-02-28
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
Distribution Media: On-line
Email: Paul.E.Racette at nasa.gov
NASA Goddard Space Flight Center Mailstop 555.0
Province or State: MD
Postal Code: 20771
Email: James.R.Wang at nasa.gov
NASA Goddard Space Flight Center Mailstop 614.6
Province or State: MD
Postal Code: 20771
NASA TOGA COARE Project Office, 1993: Mission Summary Reports, TOGA
COARE. NASA Langley Research Center, Mail Stop 483, Hampton, VA
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.
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