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Program in Arctic Regional Climate Assessment

Project Description
PARCA is a NASA project formally initiated in 1995 by combining into
one coordinated program various investigations associated with
efforts, started in 1991, to assess whether airborne laser altimetry
could be applied to measure ice-sheet thickness changes. It has the
prime goal of measuring and understanding the mass balance of the
Greenland ice sheet. The main components of the program are:

1. Periodic airborne laser-altimetry surveys along precise
repeat tracks across all major ice drainage basins. The first
survey was completed in 1993/1994, with repeat flights along
selected routes in 1995 and 1996, when flights were also made
over ice caps in eastern Canada, Svalbard, and Iceland.
Ice-thickness measurements along the same flight lines Localized
measurements of ice thickness change in shallow drill holes.
Monitoring of various surface characteristics of the ice sheet
using satellite radar altimetry, SAR, passive-microwave, AVHRR,
and scatterometer data. Surface-based measurements of ice
motion at 30-km intervals approximately along the 2000-meter
contour completely around the ice sheet, with interpolation of
local relative ice motion using interferometric SAR. Shallow
ice cores (10 - 200 meters) at many locations to infer recent
climate history, atmospheric chemistry, and interannual
variability of snow-accumulation rates, and to measure
temperature and vertical ice motion at various depths.

2. Investigations of surface energy balance and factors
affecting snow accumulation and surface ablation. This program
is a collaborative effort with NSF, and includes the
installation of automatic weather stations (AWS) at many of the
drill-hole sites.

3. Estimating snow-accumulation rates by climate-model analysis
of column water vapor obtained from radiosondes and TOVS data.

4. Detailed investigations of individual glaciers and ice
streams responsible for much of the outflow from the ice sheet.

5. Development of a thermal probe to measure various ice
characteristics at selected depths in the ice sheet.
6. Continuous monitoring of crustal motion using Global
Positioning System (GPS) receivers at coastal sites.

For more information,
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[Summary provided by University of Colorado/CIRES research group]
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