Microclimatology of a Subarctic Spruce Forest and a Clearing at Big Delta, Alaska
Microclimatology of a Subarctic Spruce Forest and a Clearing at Big Delta, Alaska

Author: Fernand De Percin

Publisher:

Published: 1960

Total Pages: 190

ISBN-13:

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This analysis deals with the microclimatology of two greatly contrasting sites at Fort Greely, Big Delta, Alaska; one in a coniferous forest (Taiga) and the other in an adjacent clearing. Continuous measurements of the vertical distribution of temperature and wind, and the measurements of solar radiation, precipitation, and globe thermometer temperatures, supplemented by the usual visual and manual observations and measurements, such as sky cover, clouds, snow depth, etc., were conducted from June 1956 through September 1957. An analysis of the data for two months, June 1956 (summer) and December 1956 (winter) is presented. (Author).

Physical Characteristics of the Snow Cover, Fort Greely, Alaska, 1966-67
Physical Characteristics of the Snow Cover, Fort Greely, Alaska, 1966-67

Author: Michael A. Bilello

Publisher:

Published: 1970

Total Pages: 44

ISBN-13:

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Observations were made at 19 sites in and around the Fort Greely Military Reservation in Alaska during the winter of 1966-67 to obtain data on the depth and physical properties of the snow cover. Snowfall in 1966-67 totaled 245 cm, which was more than 2-1/2 times the seasonal normal. Maximum snow depths of 80 to 100 cm were observed in a major portion of the reservation. Measurements at nine sites showed that the snow density at Fort Greely was generally light; e.g., the average density in the forest did not exceed 0.24 g/cu cm. However, exceptions such as at Jarvis Creek, where the density averaged 0.33 g/cu cm, could be expected. On the average, less snow falls at Fort Greely than at other interior Alaskan locations; but the average density of the snow cover at all interior Alaska sites is quite light. Relationships between snow-cover properties and climate were tested using data collected at Fort Greely. The results substantiated the relationships between (1) snow hardness and snow density measurements and (2) average snow densities with average windspeed and air temperatures. Snow temperature measurements at Fort Greely showed that the snow in the forest was colder than at exposed sites, primarily because the average air temperature within the forest canopy was lower than that in the open area. (Author).

Steady-state Two-dimensional Air Flow in Forests and the Disturbance of Surface Layer Flow by a Forest Wall
Steady-state Two-dimensional Air Flow in Forests and the Disturbance of Surface Layer Flow by a Forest Wall

Author: Joseph H. Shinn

Publisher:

Published: 1971

Total Pages: 218

ISBN-13:

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New semi-empirical models are obtained of the mean momentum transport processes in and above forests for two contrasting micrometeorological problems: (1) the equilibrium air flow in forests far upwind of any inhomogeneity in the fetch, and (2) the nonequilibrium air flow in the transition region of the surface layer flow disturbed by the entrance into a forest. The study is confined to neutral stability conditions. Experimental data are from studies in eight forests and a wind tunnel simulation. The equilibrium mean velocity profiles in forest canopies are shown to be two-dimensional. A lateral component of flow increases downward from the top of the canopy. A semi-empirical model of mean velocity components is derived and verified for the upper 90% of the forest canopy depth. In the nonequilibrium flow in the transition region downwind of a forest wall: (a) The logarithmic velocity profile is found to be an empirical approximation for the lower part of the boundary layer, assuming that only the friction velocity varies with downstream distance. An empirical relation for the horizontal variation of the friction velocity is obtained. (b) The mean velocity profiles in a mixing zone located at midcanopy level are shown to have a low-level velocity maximum and horizontal similarity. (Author).