WORKING GROUP 6 
POPHAM 
395 
landmark seen here is again Prince Edward Island and the ice pack surround 
ing it. The St. Lawrence River estuary can also be seen at the left in most of 
the pictures. 
In areas of persistent cloud cover, the problem of differentiating between ice, 
snow and clouds may be acute, especially in the polar regions where there is 
very little contrast between these features. The pictures shown in Fig. 3 were 
obtained during the break-up of the ice in the Gulf of St. Lawrence; the 
clouds can be readily distinguished from the ice and snow because the latter 
two show persistent patterns which can be identified from day to day. 
The use of stereo pairs to distinguish between ice and clouds, as well as to 
detect the direction and speed of movement of these two features when seen 
in satellite pictures, is also being studied. Tiros ii narrow-angle pictures 
obtained on two passes approximately 100 minutes apart and showing ice near 
the southwest Newfoundland coast, were examined as a stereo pair. The direc 
tion and speed of movement of the ice pack, determined by this method, 
were compared with a similar analysis of aerial photographs of the same 
area on the same day; the two measurements were found to be in very close 
agreement. 
During the analysis of Project tirec data, now in progress, the ice bound 
aries, leads and other open-water features seen in the satellite pictures will be 
delineated. Tonal gradations which might be indicative of ice of different age 
or concentration will also be noted, The interpretation of these satellite 
pictures will be compared with the visual and photographic observations of 
ice; radar and special weather observations will be used to identify ice when 
it is partially or totally obscured by clouds. Stereo methods will also be applied 
to determine the extent to which cloud or ice movement can be measured 
using satellite pictures. At present, the data gathered during Project tirec 
are still being reduced to a form which can be used for analysis.' 
The methods described above - persistence of features to identify ice or 
snow versus clouds, the interpretation of tonal variations as an indication of 
ice detail, and the application of stereo techniques to distinguish ice from 
clouds or to determine motion - are the methods which presently appear to 
be the most promising means for ice analysis and for the development of a 
routine operational satellite ice reconnaissance and surveillance program. 
The meteorologist and the oceanographer have mutual areas of interest in 
this field, and techniques or procedures adopted by one may directly benefit 
the other. Better satellite systems are being developed; new subjective and 
objective interpretation techniques are being explored; methods of correcting 
for optical or electronic picture distortion are being studied, and automatic 
methods of picture gridding and rectification are currently being designed. 
Satellite pictures which have been or are presently being obtained from the 
research and development series of tiros meteorological satellites are laying 
the ground work for future applications of satellite photographs to many 
fields other than meteorology. The use of satellites for ice studies is one of the 
newer and more promising uses of this vehicle.