A comparison was made between the resultant surface temperatures and sensible heat fluxes of building interfaces calculated by steady-state and transient (implicit) methods. Both procedures used identical environmental (summer and winter) input. For exterior conditions, the results indicated that the correlation between the two methods is sufficiently large, enabling them to be used interchangeably for the spatial analysis of urban canopy layers of entire cities. Using a steady-state approach as a surrogate for unsteady conditions, computer resources can be saved up to a factor of ten. An urban energy budget model (URBAN 3) has been used to demonstrate that the distribution of sensible heat flux and net longwave radiation -the prime causes of urban heat-island generation -was far from the homogeneity assumed in many macroscopic models or even some street-level studies. The individual emanations of reradiation and sensible heat flux showed different diurnal and spatial patterns. Under the input scenarios used, daytime heat islands assumed a 'doughnut' shape in the inner city. It is believed that many of the lower boundary conditions used in macroscopic numerical models are inadequate in light of this study.

The model WATER provides feasible computational methods for the determination of temporal and spatial agricultural water consumption. A solution was sought through the creation of a crop‐specific, growth‐stage‐specific soil moisture model. This model, which has been programmed for digital simulation, is a compromise between area‐specific, data‐based regression models and expensive, complex energy‐mass exchange models. It is suitable for evaluating the impact of droughts and other climatic vagaries on crop water requirements. Input scenarios make possible the application of the model to regions where precise data are not available.

Four typical urban surroundings were modelled, ranging from high-rise structures to low buildings and combinations thereof. These building systems were exposed to typical summer and winter climatic scenarios for latitudes 10, 34, and 50 N. Systematic variations of interior building temperatures were also introduced. The resultant changes in the components of the systems' energy budgets were examined with respect to cause and effect. The simulations produced a variety of unexpected features which intuitively had not been anticipated. It is believed that energy budget features of real cities cannot vary drastically from those simulated, and described in this report.

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WATER, a parametric crop water use model, employs climatic data to calculate water consumption for a variety of crops, using a modification of the Penman equation which included specific crop and growth stage effects. The objective of this paper was to demonstrate the response of WATER, for a grain corn crop, to changes in a variety of important environmental and decision-making inputs: air temperature, solar radiation, relative humidity, irrigation frequency, and amount of irrigation water applied. Five temperature, five solar radiation, and six relative humidity regimes were examined for an entire growing season. Also, five different water application schemes and four irrigation frequencies were included in this experiment. Additionally, the effect of different soil types, wind regimes, and groundwater depths on crop water requirements were investigated. These analyses were performed using four annual climatic scenario combinations. Among the results, evapotranspiration (ET) increased on the average by about 2.5%/1øC increase in air temperature. One percent change in solar radiation resulted in a 1.5% change in ET, while a similar change in relative humidity caused a 0.4% response in ET. Contrasting soil types, in addition to affecting irrigation frequency, were capable of changing the responding ET by over 10%. 1539

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