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The following organizations and individuals cooperated in this project:
Minister of Agriculture, Costa Rica
The Administration of San José Airport
Instituto de Cartografia, San José
Organization for Tropical Studies, San José
Tropical Science Centre, San José
Canadian Embassy in Costa Rica
National Research Council
GTW Resource Inventory Radar
Capital Air Surveys
Forest Management Institute
Description of the system
Technical details were given by Nielsen (1974) and Westby (1967 and 1975).
The most important change incorporated after 1975 into the new prototype is the
capability of changing, mostly during flight, the characteristics of the key factors
influencing performance. These include transmitter pulse length, pulse integration and
antenna beam width. ^ Also, a new capability, which provides a second profile
corresponding to the tree tops, was added.
Description of the experiment site
The requirements were similar to those of the earlier experiments, i.e. the
terrain had to be rolling and covered by typical and undisturbed virgin high tropical
forest. The forest around the field station "La Selva" belonging to the Organization for
Tropical Studies met these requirements.
"La Selva", with an average rainfall of over 3500 mm, is located close to the
junction of the rivers Sarapiqui and Puerto Viejo at 10?26'N in the Atlantic lowlands. In
this 730 ha area 320 different tree species exist, 120 of which belong to the dominant and
codominant canopy. The forest is very lush and the crown density very high. Two 200 by
200 m established research plots were of particular interest because of the large amount
of data available on them. Topography was mapped to 1 and 2 m contours, the position
of individual trees was indicated with circles of size proportional to the tree diameters,
and trees in the field were tagged. Figure 1 gives an impression of the conditions in the
field.
Two transects cutting across the test site and the two established plots were
selected and surveyed by a local contractor. One line was about 1 km in length the other
2.) km. A 1 m contour map was made for the longer, 120-m-wide strip. Cross profiles
were taken at every 20 m mark on the shorter profile.
Flight operations
The aircraft was based at San José's International Airport, about 65 km south
of the test area. To reach the area, the mountain range had to be crossed, which
sometimes was difficult due to low clouds. Although it rained every day over the test
area and there was not a single day with "photographic weather" it was possible to obtain
good large-scale photography — including colour — on 10 out of the 16 days available for
flying.