Abstract:
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
improve 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 the 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 system.
The University of North Dakota owns and operates a Cessna Citation II
aircraft (N77ND) for the purpose of atmospheric research. This
aircraft type has a number of design and performance characteristics
which make it an ideal platform for a wide range of atmospheric
studies. A series of structural modifications have been made to the
basic airplane. These include the following: pylons under the wing
tips for a variety of probes in the undisturbed air flow away from the
fuselage; a nose boom for wind measurement; a heated radome to prevent
ice accumulation on the nose area; special mounts for upward and
downward looking radiometers; side-facing camera mounts for time-lapse
cameras; optically-flat glass windows for photography; and an air
inlet port for air sampling inside the pressurized cabin. The
research instrumentation available on the Citation for the second
Cirrus IFO is described below.
The basic instrumentation package measured temperature, dew point
temperature, pressure, wind and cloud microphysical characteristics
along with aircraft position, altitude and performance parameters. The
three-dimensional wind field is derived from measurements of
acceleration, pitch, roll and yaw combined with angles of attack and
sideslip and indicated airspeed. The aircraft parameters were supplied
by an LTN-76 inertial navigation system and a Global Positioning
System (GPS). Turbulence intensity can be derived from differential
pressure transducers and INS accelerometer outputs.
Cloud microphysical measurements were made with an array of Particle
Measuring Systems probes (FSSP, 1D-C,2D-C,1D-P) mounted on the
wing-tip pylons. These probes measure concentrations and sizes of
particles from one micrometer to several millimeters in diameter. In
addition there were probes to measure both liquid water content and
icing rate. Several gas and aerosol sampling instruments were
available. These include fast response O3 and NO2 monitors, and a
condensation nuclei counter.
A forward or side-looking video camera was also used to provide a
visual record of flight conditions. The data were sampled at various
rate from 1 to 24 sec-1. The sampling is controlled by the on-board
computer system which also displayed the data in real time in graphic
and alphanumeric formats while recording them on magnetic tape. 
