Another trend is towards automation and computer-supported models for ice 
motion. 
Research results emanating from other organizations concerned with remote 
sensing applications in ice reconnaissance, such as from the United States Naval 
Oceanographic Office, indicate the direction of future developments, which include 
automatic recognition of ice conditions (Gerson and Rosenfeld, 1975), and more 
extensive use of highly sensitive correlation and power spectrum analysis for 
interpretation of laser profiles (Tooma and Tucker, 1973). 
It is normal and appropriate that the procedures of operational programs, 
such as Ice Branch, do not incorporate the latest results of research, or procedures 
that are just beginning to emerge from the developmental stages. This delay is 
partly caused by financial constraints and learning time, but even more important 
is that those responsible for an operational program cannot underwrite the risk of 
accepting methods whose reliability over a wide range of conditions has not been 
proved, nor can they afford the inevitable disruptions which result if one part of a 
complicated system is changed to a new method which, although apparently more 
powerful and efficient, is nevertheless out of balance with other parts of the 
System. 
Air pollution 
In the monitoring and surveillance of air pollution, remote sensing techniques 
have the advantages of efficiency and objectivity over visual observations. In 
addition, there is the ability of rapid response and the opportunity to check the 
activities of potential pollutors without warning and interference. Disadvantages 
may include cost, compilicated calibration procedures, inability to operate under 
some weather conditions and, for a few laser devices, an eye safety hazard. 
Ludwig and Griggs (1975) present a recent summary of developments in the 
remote sensing of air pollution. A high proportion of the instruments described are 
still at the development or testing stages, and we are obviously in a new and rapidly 
changing field. Many instruments are not airborne, but based on the ground, 
frequently in mobile units. Remote sensing equipment includes both active and 
passive systems operating in the visual, infrared and ultra-violet regions of the 
spectrum. The authors discuss the merits of the individual Systems and conclude 
that the following important air pollutants are today, or will soon be effectively 
monitored by remote systems: 305, NO, CO, light hydrocarbons, HC1, HF, NH, 
Has, HNO and vynil chloride. Active systems such as lidar, laser, and raman 
instruments, have greater capabilities in complex assessments of plume temper- 
ature and pollutant concentration. Passive systems, such as photography and 
correlation instruments, are more subject to background interference, but they 
tend to be cheaper and, therefore, have useful applications. 
Remote sensors on meteorological and other satellites also provide infor- 
mation on air quality. We know from observations of dust storms originating from 
the dry bed of California's Lake Owens that the plumes of these storms can be seen 
on NOAA-4 imagery (Reinking, Mathews and St. Amand 1975). If we can combine a 
knowledge of the area affected under given conditions with meteorological data, 
then both forecasts and assessments of the magnitude of problems associated with 
these storms can be made. It is also known that aerial photography and satellite 
imagery are reliable means of evaluating vegetation damage caused by air 
pollution. For example, Murtha (1972b, 1973) describes how both small scale 
(1:160,000) photography and Landsat can be used for 50, damage appraisal.