IRIAN JAYA, INDONESIA, and NEW ZEALAND

Imaging of Glaciers
Aerial Photography
The first known sequences of vertical aerial photographs in New
Zealand were taken around 1937 and 1938 by New Zealand Aerial Map­
ping, Ltd., but these were mainly of lowland areas. A set of vertical
aerial photographs was taken over the Franz Josef, Fox, Tasman, and
Hooker Glaciers in 1953, followed by a most useful set of oblique aerial
photographs taken by the Royal New Zealand Air Force along both sides
of the Southern Alps in autumn 1955. These surveys were made just
prior to the first of the systematic vertical aerial photographic flights
made over the Southern Alps as part of a nationwide aerial photo-
grammetric mapping program. By the end of the 1960's all of the
glacierized areas were photographed, and many areas have been re-
photographed since.
Satellite Imagery
All of New Zealand's glacierized areas are included in existing Landsat
images, but not all of the images are usable for glacial observations
(fig. 8). The two requisites for an optimum usable image are no cloud
cover and an image acquired at the time of minimum snow cover (late
summer). Many of the better images of the glacierized areas have glacial
features obscured by seasonal snow. The coding for each of the nominal
scene centers shown on figure 8 refers primarily to the amount of cloud
cover over the glacierized regions. Table 1 provides additional informa­
tion on each image, including remarks about amount of snow cover.
Table 1 lists the known usable images of the New Zealand glaciers.
Many additional images exist, but these are generally unacceptable be­
cause of excessive cloud cover or because of snow cover on winter
scenes. Unfortunately, the Landsat satellite paths and image rows do
not coincide well with the configuration of the glacierized areas. This
results in images of the more important glacerized regions appearing at
the margins of the images. The best available image of the Mount Cook
area is the larger scale (1:500,000) Landsat 3RBV image (30324-21342,
subscene A), corresponding to the northwest quadrant of Path 79, Row
91, but this image lacks relief detail in the snowfields (Ferrigno and
Williams, 1983).
Landsat images are more appropriate for the larger glaciers, because
the spatial resolution of the image is inadequate for identifying details of
small glaciers less than about 1 or 2 km2 in area. On a l:l,000,000-scale
Landsat MSS image 1 km equals 1 mm, so a 1-km2 glacier would
measure 1 mm2 on the image. Even on a 1:500,000-scale Landsat 3 RBV
image, a 1-km2 glacier would only be 4 mm2 . Unfortunately the rapid
changes in small, steep, and very active glaciers, such as the one shown
in figure 9, are difficult to monitor by satellite imagery. On some small
glaciers the snowline has recently risen beyond the upper limits of the
glacier, thereby leaving the entire glacier in the ablation zone (fig. 10).
H36 SATELLITE IMAGE ATLAS OF GLACIERS OF THE WORLD