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 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.
For more information about the UND Citation see
http://www.atmos.und.edu/f2_Research/f1_Research%20Aircraft/researc...
Cloud microphysical measurements were derived from data taken by the
University of North Dakota Citation aircraft PMS 2D-C and 2D-P probes
during the FIRE Cirrus IFO - II. Following are a list of parameters
collected:
VARIABLE DESCRIPTION UNITS
-------------------------------------------------------------------------------
IT1,IT2 MEASUREMENT TIME INTERVAL HH/MM/SS
PS STATIC PRESSURE mb
TEMP AMBIENT TEMPERATURES degrees C
ALT PRESSURE ALTITUDE m
USTAR VERTICAL VELOCITY NEEDED TO KEEP THE cm/s
RELATIVE HUMIDITY CONSTANT
DBARM MEDIAN PARTICLE MASS WEIGHTED DIAMETER cm
DMAX MAXIMUM PARTICLE DIAMETER cm
W1 DIFFUSIONAL GROWTH RATE IN CHANNEL 1 g/sec
W2 DIFFUSIONAL GROWTH RATE IN CHANNEL 2 g/sec
W3 DIFFUSIONAL GROWTH RATE IN CHANNEL 3 g/sec
W4 DIFFUSIONAL GROWTH RATE IN CHANNEL 4 g/sec
WTOT TOTAL DIFFUSTIONAL GROWTH RATE g/sec
DT8 DEPLETION TIME (8 micron droplets) sec
DT12 DEPLETION TIME (12 micron droplets) sec
TMASS1 IWC IN CHANNEL 1 g/m^3
TMASS2 IWC IN CHANNEL 2 g/m^3
DPTC DEW POINT TEMPERATURE (EG&G) degreesC
RH RELATIVE HUMIDITY (EG&G) %
RIWC ICE WATER CONTENT g/m^3
XM1 ICE WATER CONTENT BASED ON SNOW HABIT g/m^3
XM2 ICE WATER CONTENT BASED ON SMALL SNOW g/m^3
HABIT
XM3 ICE WATER CONTENT BASED ON LARGE SNOW g/m^3
HABIT
R PRECIPITATION RATE mm/hr
DBZ RADAR REFLECTIVITY FACTOR decibels
VBAR MEAN REFLECTIVITY WEIGHTED WITH THE cm/s
TERMINAL VELOCITY
TTCONC TOTAL PARTICLE CONCENTRATION #/L
CBIN1 PARTICLE CONCENTRATION WITHIN
THE RANGE LE 200 #/L
CBIN2 PARTICLE CONCENTRATION WITHIN 200-500 #/L
THE RANGE
CBIN3 PARTICLE CONCENTRATION WITHIN THE 500-800 #/L
RANGE
CBIN4 PARTICLE CONCENTRATION WITHIN THE #/L
RANGE GT 800
CE8 COLLECTION EFFICIENCY (8 micron none
droplets)
CE12 COLLECTION EFFICIENCY (12 micron none
droplets)
TMASS3 IWC IN CHANNEL 3 g/m^3
TMASS4 IWC IN CHANNEL 4 g/m^3
TIMP # OF CRYSTAL-CRYSTAL COLUMNS sec^(1-)
RHORH WATER VAPOR DENSITY g/cm^3
SI SUPERSATURATION WITH RESPECT TO ICE %
SW SUPERSATURATION WITH RESPECT TO WATER %
LAMBDA COEFFICIENTS USED TO FIT THE EQUATION #/cm^3
NZERO N=N0*EXP(-LAMBDA*D) #/L/mm
RSQ COEFFICIENT OF THE FIT none
ICP PROBE TYPE (C OR P) none