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. 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 June 1-28, 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 Cloud Lidar System (CLS) instrument was flown aboard the NASA ER-2
airplane. This instrument was used to determine cloud altitudes.
Information pertaining to the number of cloud layers detected; the
heights of the boundaries for up to 5 cloud layers; geo-physical
location information; and time were recorded.
Four channels of data were recorded. The first channel recorded wave
lengths at 532 nanometers in the parallel plane. The second channel
recorded wave lengths of 532 nanometers in the perpendicular plane.
The third channel recorded wavelengths of 1064 nanometers total. The
forth channel was a linear amplifier which received the digitized
signal from one of the three previously mentioned CLS detectors.
The data are organized so that there is a single header record for the
file. This header record is followed by a series of pairs of records.
The first record of each pair contains the CLS calibrated data and the
second record of the pair contains the CLS analyzed data.