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 systems.
The development of parameterizations requires an understanding of the
processes that generate, maintain, and dissipate boundary layer
clouds. This development is currently impeded by lack of understanding
of the transition from stratocumulus clouds to trade cumulus clouds
and the factors that control cloud type and amount in the boundary
layer. The Atlantic Stratocumulus Transition EXperiment (ASTEX) was
designed to address key issues related to stratocumulus to trade
cumulus transition and mode selection. ASTEX involved intensive
measurements from several platforms operating from 1-28 June 1992 in
the area of the Azores and Madeira Islands. The purpose was to study
how the transition and mode selection are effected by 1) cloud-top
entrainment instability, 2) diurnal decoupling and clearing due to
solar absorption, 3) patchy drizzle and a transition to horizontally
inhomogeneous clouds through decoupling, 4) mesoscale variability in
cloud thickness and associated mesoscale circulations, and 5) episodic
strong subsidence lowering the inversion below the LCL. Detailed
descriptions of the scientific goals of ASTEX are in the FIRE Phase
II: Research plan (1989) and in the ASTEX Operations Plan (1992).
The University of Washington Convair data are best considered raw at
this point and should be validated by comparing with data collected
from other platforms where possible if high accuracy is desired.
Of the three measures of liquid water content available from the
Convair, the Johnson-Williams (JW) hot-wire probe is considered the
most readily usable, although there is a significant drift in the
output that should be accounted for. The Forward Scattering
Spectrometer Probe (FSSP) measured the liquid water content using
optical scattering principles. 
