Accession Number : AD0674760

Title :   ADAPTATION BETWEEN THE PRESSURE AND THE WIND FIELD IN MESO- AND SMALL-SCALE MOTIONS,

Corporate Author : EMMANUEL COLL BOSTON MASS ORIENTAL SCIENCE RESEARCH LIBRARY

Personal Author(s) : Yeh Tu-Cheng, ; Li Mai-Tsun,

Report Date : MAY 1968

Pagination or Media Count : 29

Abstract : It is pointed out that in addition to the so-called geostrophic adaptation in a large-scale motion, there is an adaptation between the pressure and the wind field in meso- and small-scale motions. Scale analysis shows that in the equations of motion (meso- or small-scale), the term for the time derivative is an order of magnitude smaller than the main terms. Hence, we may assume that motions of such scales evolve slowly in a quasi-balanced state. If, for any reason, this state of motion is disturbed, there will be a mechanism to restore it. A quasi-balanced state exists between the inertial force (velocity advection), the coriolis force and the pressure gradient force. The progression from disturbance to restoration of a quasi-balanced state is known as an adaptive process and the evolution in a quasi-balanced state a quasi-steady process. The physical nature of these two processes is discussed. It is shown that for a meso-scale motion, D>>zeta in an adaptive process and D = or < zeta in a quasi-steady process, D and zeta being the divergence and vorticity, respectively. If in some limited region the balanced state of the motion is violently disturbed, further development of this motion may be calculated as an initial-value problem. Calculated results show that within the initial short time interval, the meteorological elements undergo a rigorous change in which the quasi-balanced state is re-established and the motion enters a quasi-steady state. (Author)

Descriptors :   (*ATMOSPHERIC MOTION, *WEATHER FORECASTING), (*MICROMETEOROLOGY, WEATHER FORECASTING), CORIOLIS EFFECT, THUNDERSTORMS, BAROMETRIC PRESSURE, AIR MASS ANALYSIS, WIND, ATMOSPHERE MODELS, BOUNDARY VALUE PROBLEMS, NUMERICAL ANALYSIS, CHINA

Subject Categories : Meteorology

Distribution Statement : APPROVED FOR PUBLIC RELEASE