Accession Number:

AD0605527

Title:

The Energy Budget at the Earth's Surface. Part 2. Studies at Ithaca, NY, 1960

Descriptive Note:

Production research rept.

Corporate Author:

AGRICULTURAL RESEARCH SERVICE ITHACA NY

Personal Author(s):

Report Date:

1963-09-01

Pagination or Media Count:

54.0

Abstract:

This report presents in part the results of research conducted with the particular objective of evaluating the aerodynamic surface roughness and relating it to the elastic and geometric characteristics of the surface cover. Theoretical and experimental investigations of the turbulent transfer characteristics of the air-stream near the ground are reported. It is shown that the surface boundary layer must be divided into two regions the freestream above the surface where the various forms of turbulent transfer are nearly independent of height, and the airstream within the vegetative canopy where sources and sinks are present. Several theoretical models for canopy flow are reported and compared with observations. A numerical method for determining the aerodynamic characteristics and their standard errors in the freestream is described. Experimental results for freestream and canopy flow are reported. It is concluded that canopy flow is fully turbulent and that the observations satisfy best a theoretical model in which the mixing length is a function of height above the ground surface. Experimental data show that the aerodynamic surface roughness varies with the windspeed and the variations depend upon the geometric and elastic characteristics of the vegatation.

Subject Categories:

  • Energy Storage

Distribution Statement:

APPROVED FOR PUBLIC RELEASE