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  • Author or Editor: R. T. H. Collis x
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R. T. H. Collis

Increasing demand is outstripping world food production, despite increased yields due to technological progress. Combined with adverse weather and governmental policies, this has led to a major rundown of reserve grain stocks over the last few years. Without adequate reserves to provide equalization, weather must now be recognized as a critical factor in balancing the supply and demand of world food. Regardless of long term trends, such as the return of an Ice Age, unsettled weather conditions now appear more likely than those of the abnormally favorable period which ended in 1972. This possibility and its implications must be considered in planning and determining national and world food policies. There is an urgent need for better understanding and utilization of information on weather variability and climatic change in this context.

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R. T. H. Collis

Lidar, using pulsed lasers as energy sources, applies the radar principle at wavelengths in and near the visual spectrum to probe the atmosphere. It can detect particulate matter of much smaller dimensions and sparser concentration than is possible with meteorological radar. Lidar may be used to measure cloud base heights although difficulties arise with diffuse clouds, especially in foggy conditions. Inhomogeneities in turbidity that occur at the heights of temperature inversions in the relatively clear atmosphere are also revealed by lidar. Examples of work in progress that show promise of providing a measurement of visibility are presented.

It is concluded that lidar can already contribute usefully in routine meteorological service, but that its full potential in ceilometry and visibility measurement awaits further developments. For routine unattended use, high pulse-rate low peak-power lidars are advocated on grounds of safety.

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D. A. Leone, R. M. Endlich, J. Petričeks, R. T. H. Collis, and J. R. Porter

A systematic and objective approach was used to optimize the siting of the individual radars forming the Next Generation Weather Radar (NEXRAD) network. Prime consideration was given to meteorological factors, in conjunction with the user agencies' needs and the population distribution. The latter was assessed by a novel technique using weather satellite photographs showing urban illumination at night. Priority coverage areas were identified for population centers based on the expected paths of storms and their travel speeds. Radar viewing of the priority coverage areas down to low altitudes is needed so that approaching storms can be detected and warnings issued as early as possible. Other siting criteria taken into account included consideration of terrain features and local obstructions, locations of airways and civilian and military airports, electromagnetic interference, and integration of NEXRAD data into the national weather system.

The methodology for selecting the network is described. Environmental impacts and costs of site acquisition and preparation were also involved in the study, but are not discussed in this paper.

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