Accession Number : AD0605830

Title :   THERMAL UPPER LIMIT ON EDDY DIFFUSION IN THE MESOSPHERE AND LOWER THERMOSPHERE,

Corporate Author : GRADUATE RESEARCH CENTER OF THE SOUTHWEST DALLAS TEX

Personal Author(s) : Johnson,Francis S. ; Wilkins,Eugene M.

Report Date : 1943

Pagination or Media Count : 8

Abstract : The thermodynamic stability of the mesosphere and lower thermosphere requires that there be a downward transport of heat associated with any turbulent mixing. The amount of available heat that could be transported downward through any level by eddy conduction can be determined from the absorption of solar energy above that level. This can be used to place an upper limit on the eddy coefficient, and this limit is substantially below values frequently quoted on the basis of vapor or meteor trail studies. The upper limit is about 1000000 sq cm/s above 80 km and about 4 x 100000 sq cm/s from 50 to 70 km. The fact that diffusive equilibrium distributions of atmospheric constituents prevail no lower than 105 km, where the molecular diffusion coefficient is 1000000 sq cm/s, indicates that the eddy coefficient at that altitude has the limiting value indicated by the thermal structure. (Author)

Descriptors :   (*UPPER ATMOSPHERE, THERMAL PROPERTIES), (*DIFFUSION, UPPER ATMOSPHERE), ATMOSPHERES, THERMODYNAMICS, STABILITY, TURBULENCE, ABSORPTION, SOLAR RADIATION, GEOPHYSICS, HEAT TRANSFER

Distribution Statement : APPROVED FOR PUBLIC RELEASE