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Robert A. Sutherland

Abstract

A relatively simple, objective, nocturnal temperature forecasting model suitable for freezing and near-freezing conditions has been designed so that a user, presumably a weather forecaster, can put in standard meteorological data at a particular location and receive an hour-by-hour prediction of surface and air temperatures for that location for an entire night. The user has the option of putting in his own estimates of wind speeds and background sky radiation which are treated as independent variables. An analysis of 141 test runs show that 57.4% of the time the model predicts to within 1°C for the best cases and to within 3°C for 98.0% of all cases.

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Robert A. Sutherland

Abstract

No abstract available.

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Robert A. Sutherland

Abstract

Broadband and spectral emissivities of several soil types, grass and tree leaves are reported for wavelengths between 2 and 18 μm. Broadband measurements were made in situ with an 8–14 μm bandpass radiometer, and spectral measurements were made in the laboratory with a dual beam Fourier transform spectrometer. Broadband emissivity was nominally 0.89–0.92 for sands, 0.96 for clay, and 0.97–0.99 for peat, muck and grass. The emissivity spectra indicated near-greybody behavior for vegetation but marked departures near 9–10 μm for the sands.

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Montie M. Orgill
,
John D. Kincheloe
, and
Robert A. Sutherland

Abstract

The mesoalpha-scale upper-level sounding network data collected during the 1984 ASCOT meteorological and tracer experiments provided a unique opportunity to analyze the nocturnal drainage wind in four different valleys in western Colorado, and to examine the effects of the synoptic-and mesoscale ambient conditions on these valley drainage winds. The six experimental periods, although biased because of a “fair weather” selection process, provided an additional opportunity to examine “good” and “poor” drainage scenarios. The results show that drainage winds fill all four valleys up to 80%–l00% of their valley depths under favorable nocturnal radiative longwave cooling (1.0°–1.5°C h−1) and light (<5 m s−1) ambient winds. Valley drainage, once established, is rather resistant to erosion from above because of the large source regions of these valleys, their large volume fluxes and inertia, and the persistent stable conditions inside these valleys. Wind erosion was observed on three nights when the drainage depth was reduced to less than half of the valley depth. The principal contributing factors to wind erosion processes were above-valley along-valley wind component opposing the drainage, valley stability, height of the 5 m s−1 isotach above the valley, and total above-valley wind acceleration. Generally, wind erosion processes appear to be especially active when above-valley wind speeds exceed 5 m s−1 and accelerations exceed 0.00040 m s−1. Other contributing factors that cause variable or terminated drainage depths are precipitation-evaporation effects causing nonradiative drainage events, wind shear above the valley, cloudiness, frontal passages, and synoptic winds directed in the down-valley direction.

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Montie M. Orgill
,
John D. Kincheloe
, and
Robert A. Sutherland

Abstract

An experimental weather classification, analysis, and nowcasting system, based upon a combination of artificial intelligence techniques and conventional numerical modeling, and designed for use as a real-time range/field forecasting aid, is described. In particular, a computer-based prototype coupled knowledge-based system, called PROCANS (Prototype Coupled Analysis and Nowcasting System), tailored for applications at the U.S. Army field testing range at Fort Hunter Liggett, California, is used as an example to demonstrate and evaluate the overall concept. The components of the system are: 1) a rule-based meteorological scenario evaluator for analysis and classification of weather scenarios, 2) a nowcaster that uses four analogical and rule-based expert subsystems for nowcasting radiation fog, wind gustiness, thunderstorms, and precipitation, 3) a numerical transport and diffusion module based upon either Gaussian or Monte Carlo particle-trajectory models to simulate airflow and diffusion patterns, and 4) a master database for storing information for possible retrieval, comparing current weather scenarios with past scenarios for possible matching and for analogical and conceptual reasoning to aid future predictions. A preliminary evaluation of PROCANS shows that coupled knowledge-based systems have potential as an integrated local analysis and prediction tool or forecaster's aid for field operations such as smoke screening.

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Robert A. Sutherland
,
Jane L. Langford
,
Jon F. Bartholic
, and
Robert G. Bill Jr.

Abstract

A real-time satellite data acquisition, analysis and display system is described which uses analog data transmitted by telephone line over the GOES network. Results are displayed on the system color video monitor as “thermal” images which originated from infrared surface radiation sensed by the Geostationary Operational Environmental Satellite (GOES).

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