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Donald J. Perkey
,
Kevin N. Young
, and
Carl W. Kreitzberg

Newspapers, television, and newsweeklies contained numerous articles proclaiming drought conditions during 1980 and 1981. This study investigates the causes and consequences of the drought as it affected eastern Pennsylvania. Precipitation data indicate below-average amounts during this period, while temperature records show above-average values. These values show that a meteorological drought did occur in this region during 1980 and 1981. However, meteorological factors were only part of the cause of the region's water shortage.

In addition to analyzing the drought's meteorological origin, this study probes the anthropogenic and regional social-political causes and impacts of the water shortage. Although regional water storage facilities are adequate when below-average precipitation amounts occur in very local areas, they are not adequate when below-average amounts occur over larger regions. This inadequacy is compounded when demands such as the needs of other political regions and the river-basin ecological system are included in addition to the primary region's industrial and domestic water requirements. Thus, this paper illustrates some of the complexities involved in trying to prepare for the normal fluctuations in a climatic variable such as precipitation amount.

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Tsing-Chang Chen
,
Chia-Bo Chang
, and
Donald J. Perkey

Abstract

The diabatic effects of latent heat release, boundary layer moisture and heat flux from the ocean surface and large-scale forcing due to upper-level systems are three physical processes affecting oceanic cyclogenesis. Detailed analyses of a major winter storm which occurred during the initial phase of the Air Mass Transformation Experiment in 1975 (AMTEX '75) indicated that the role of these three processes was vital to the Cyclone's development. To gain further insight into their influence, a control and three numerical experiments were performed using a multi-level moist primitive equation model with fine vertical resolution in the boundary layer.

The simulation which included complete physics faithfully reproduced the major feature of the observed system. It was found that latent heating had a profound impact on the middle-level baroclinicity, the intensity and phase speed of the storm, and the vertical coupling within the simulated system. Without the surface moisture and heat source, the effects of the model moist processes were greatly reduced, suggesting that the effects of air-sea interaction are important even for short-range (24 h) numerical weather prediction of oceanic cyclones. The exclusion of the large-scale forcing resulted in a rather shallow model system. The dynamic response to diabatic heating became disorganized without the large-scale influence.

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