Abstract:
The ABLE missions have been designed specifically to study the rate of
exchange of material between the Earth's surface and its atmospheric
boundary layer, and the processes by which gases and aerosols are
moved between the boundary layer and the 'free' troposphere. These
expeditions are conducted in ecosystems of the world that are known to
exert a major influence
... on global atmospheric chemistry. In some
cases, these ecosystems are undergoing profound changes as a
consequence of natural processes and/or human impact.ABLE 3A is a
component of the NASA Global Tropospheric Experiment (GTE) sponsored
by the NASA Tropospheric Chemistry Program.
The Arctic Boundary Layer Expedition (ABLE 3A) was conducted in Arctic
and sub-Arctic regions of North America and Greenland during July and
August 1988. ABLE 3A was the first comprehensive investigation of the
sources, sinks, and distribution of trace gas and aerosol chemical
species in a northern high-latitude region during summer months. The
ABLE 3A experimental design placed emphasis on the role of
biosphere-atmosphere interactions in determining the chemical
composition of the troposphere and on processes which influence the
tropospheric ozone budget. The suite of chemical species measured
included the following gases: methane, carbon monoxide, carbon
dioxide, total "reactive" nitrogen gas, nitric acid, peroxyacetyl
nitrate, peroxypropionyl nitrate, ozone, and aerosol chemical
composition and size distribution. The instruments used included a
capacitive sensor, chilled mirror, Differential Absorption Lidar
(DIAL), electron capture detector-gas chromatograph, grab samples/gas
chromatograph, inertial navigation system, photoelectric cell,
resistance temperature detector, two photon/laser induced
fluorescence, and a tunable diode laser.
The ABLE 3A results indicate that human activities may have already
enhanced total "reactive" nitrogen inputs to the Arctic and Sub-Arctic
regions to the extent that the lifetime of ozone against photochemical
loss may have already doubled.
This data set consists of the aircraft measurements of chemical
species. There are also ABLE 3A data sets for a ground site
(GTE_A3A_TOWER), for isentropic back trajectories generated for the
program time frame (GTE_A3A_MET_TRAJ) and a data set for airborne flux
measurements of trace species (GTE_A3A_ELEC_FLUX). These data sets
are also available from the Langley DAAC. 
