The First ISCCP Regional Experiments have been designed to improve
data products and cloud/radiation parameterizations used in general
circulation models (GCMs). Specifically, the goals of FIRE are (1) to
seek the basic understanding of the interaction of physical processes
in determining life cycles of cirrus and marine stratocumulus systems
and the radiative ... properties of these clouds during their life cycles
and (2) to investigate the interrelationships between ISCCP data, GCM
parameterizations, and higher space and time resolution cloud data.
To-date, four intensive field-observation periods were planned and
executed: a cirrus IFO (October 13 - November 2, 1986); a marine
stratocumulus IFO off the southwestern coast of California (June 29 -
July 20, 1987); a second cirrus IFO in southeastern Kansas (November
13 - December 7, 1991); and a second marine stratocumulus IFO in the
eastern North Atlantic Ocean (June 1 - June 28, 1992). Each mission
combined coordinated satellite, airborne, and surface observations
with modeling studies to investigate the cloud properties and physical
processes of the cloud systems.
The MODIS Airbourne Simulator (MAS) is a modified Daedalus Wildfire
scanning spectrometer which flies on a NASA ER-2 and provides spectral
information similar to that which will be provided by the Moderate
Resolution Imaging Spectroradiometer (MODIS), scheduled to be launched
on the EOS-AM platform in 1998 (King et al. 1992). The principal
investigators for the MAS are Dr. Michael King (NASA/GSFC, Greenbelt
MD), and Dr. Paul Menzel (NOAA/NESDIS, Madison WI).
In January 1992, the modified Wildfire instrument was converted to MAS
configuration. In June 1992 the MAS was flown over portions of the
Atlantic Ocean in the region of the Azores during the ASTEX
experiment. Although the MAS instrument is a 50 band spectrometer,
the data system used in this experiment could only record 12 channels
(at 8-bit resolution).
The MAS spectrometer acquires high spatial resolution imagery in the
wavelength range of 0.55 to 14.3 microns. A total of 50 spectral bands
are available in this range, and the digitizer can be configured to
collect data from any 12 of these bands. The digitizer was configured
with four 10-bit channels and seven 8-bit channels. The MAS
spectrometer was mated to a scanner subassembly which collected image
data with an IFOV of 2.5 mrad, giving a ground resolution of 50 meters
from 20000 meters altitude, and a cross track scan width of 85.92
degrees. The data granules were written using the self documenting
file storage format provided through the netCDF interface routines
included in the HDF libraries.