Advanced Microwave Moisture Sounder (AMMS) Measurements Taken Onboard the NASA DC-8 During the TOGA COARE Intensive Observing PeriodEntry ID: COARE_cm_dc8.amms
Abstract: DATA ACCESS
The NASA TOGA COARE Data Archive
The AMMS data are available from the NASA GSFC DAAC via ftp from
daac.gsfc.nasa.gov in subdirectory pub/toga_coare/aircraft/nasa_dc8/amms or
ftp://disc1.gsfc.nasa.gov/data/toga_coare/aircraft/nasa_dc8/amms. To request
data on tape, contact the DAAC ... User Services Office. For more information
contact Pat Hrubiak at email@example.com.
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 AMMS instrument, which was mounted on NASA's DC-8 aircraft for the
TOGA COARE Field Experiment, is a scanning radiometer that measures
brightness temperatures in degrees Kelvin. It was operational during
16 mission flights of the DC-8 between 5 January and 23 February 1993.
The AMMS was designed to profile atmospheric water vapor and was
mainly used for this purpose in the past. It is also sensitive to
cloud cover and precipitation. Because the weighting functions of its
four frequency channels peak at different altitudes, depending on
water vapor density and profile, AMMS has the potential of estimating
the height of frozen hydrometeors associated with a convective
storm. For TOGA COARE the sensor was combined with other radiometers
in the same aircraft to measure the radiometric response of convective
rainfall systems in the frequency range of 10-183 GHz.
AMMS is a 4-channel, mechanically scanned, imaging microwave
radiometer operating at 92, 183.3+/-2, 183.3+/-5, and 183.3+/-9
GHz. It has a 15-cm aperture giving an angular resolution of about 2
degrees at 92 GHz and 1 degree at 183 GHz. After every 6 scans, the
beam is directed to view heated (330 K) and cooled (250 K) external
calibration targets for 2 seconds each, resulting in a total frame
time of approximately 30 seconds (including slewing time). The
radiometric signals and the measured physical temperatures from these
calibration targets form the basis for the derivation of the scene
brightness temperatures. The calibration accuracy is on the order of 1
K in the 250-300 K brightness temperature range. The temperature
sensitivity (delta T) of the sensor has gradually deteriorated over
the past 10 years. For water vapor profiling, averaging of up to 50
radiometric samples is needed to meet the requirement of delta T of <=
1 K. The microwave signatures from precipitation are much stronger
than water vapor at the AMMS frequencies, and data from this sensor
will be sufficient to derive important information about the
The beam is scanned in 50 steps of 1.8 degrees from nominally 45
degrees to the right through nadir, and to 45 degrees to the left with
a total scan time of approximately 4 seconds. For TOGA COARE, only the
left half of the scan (25 steps, from nadir to the left of the
aircraft) is useful because of the geometry of nadir port in which it
is mounted in the aircraft.
One data product consisting of 16 ASCII files of calibrated brightness
temperatures in degrees Kelvin was produced by the AMMS instrument
during the TOGA COARE Field Experiment. Each file contains data from 1
flight. File size ranges from 2.8 to 4 MB. The total data volume is 55
MB. There are 10 parameters in each file. 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,
also available on FTP.
Data Set Citation
Dataset Originator/Creator: TOGA COARE
Dataset Title: Advanced Microwave Moisture Sounder (AMMS) Measurements Taken Onboard the NASA DC-8 During the TOGA COARE Intensive Observing PeriodOnline Resource: http://disc.gsfc.nasa.gov/fieldexp/TOGA/
Start Date: 1993-01-01Stop Date: 1993-02-28
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 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., W.C. Boncyk and A.K. Sharma, 1993: Water Vapor Profiling
over Ocean Surface from Airborne 80 and 183 GHz Radiometric
Measurements Under Clear and Cloudy Conditions IEEE Transactions on
Geoscience and Remote Sensing, 31(4), 853-859.
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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