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
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 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 ASTEX/MAGE experiment is a multinational effort to improve our
capability for studying cloud-chemistry interactions and the air/sea
fluxes that affect them. The primary purpose of ASTEX (with which
MAGE collaborated) was to study the factors influencing the formation
and dissipation of marine clouds.
The specific goals of the MAGE atmospheric chemistry experiment in
ASTEX included:
- Develop and test a Lagrangian strategy for studying chemical and
meteorological evolution in a tagged airmass, using ships, balloons,
and aircraft.
- Develop and test new techniques for estimating trace-gas and aerosol
fluxes across the air/sea interface by comparison with traditional
approaches.
- Evaluate the impact of marine and continental aerosols on the
formation and dissipation of stratocumulus clouds.
- Compare the impacts of natural and anthropogenic sulphur, halogens,
and hydrocarbons on marine aerosol chemistry.
- Gain experience with multi-national and multi-agency field
experiments as a means for addressing global tropospheric chemistry
issues.
The North Carolina State University tetroons were launched from the
ship Oceanus in support of the FIRE-ASTEX observational program,
conducted in the eastern North Atlantic during the month of June 1992.
Special constant density balloons were launched and then tracked for
48 hours -- with the idea that they were tracking a single parcel of
air. The parameter #sats gives the number of GPS satellites available
for positioning. Four satellites are necessary to determine altitude,
otherwise the last available altitude from four satellites is assumed
to remain constant, so that the horizontal location can be
triangulated from three satellites. An altitude is always given in
the file, so care should be taken as to its use.
Each tetroon attempted to fix its location once every 5 minutes of
operation. Each tetroon was given an offset in transmission time
during the 5 minute period in which to transmit its location in order
to allow all tetroons to broadcast on the same frequency. The time at
which a position fix was made and the relevant location information is
provided for each tetroon. In the event no fix was possible due to
the satellite constellation configuration, number or signal strength,
no position was transmitted. Each position was retransmitted at 1/2
hour increments for seven hours to attempt to obtain the maximum
amount of data, even for periods when aircraft were not in the area of
transmission. 
