Accession Number : AD0250571

Title :   STRUCTURE OF TURBULENCE AND MEAN WIND PROFILES WITHIN THE ATMOSPHERIC BOUNDARY LAYER

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK

Personal Author(s) : BLACKADAR, ALFRED K. ; PANOFSKY, HANS A.

Report Date : 31 OCT 1960

Pagination or Media Count : 1

Abstract : WIND PROFILES AT VARIOUS LOCATIONS ARE COMPARED WITH PREDICTED WIND PROFILES ON THE BASIS OF SIMILARITY THEORY. THEORY AND OBSERVATION ARE SHOWN TO AGREE WELL FOR NEAR NEUTRAL AND UNSTABLE AIR. IN STABLE AIR FACTORS NOT CONSIDERED IN THE SIMILARITY THEORY APPEAR TO BECOME IMPORTANT. THE RANGE OF USEFULNESS OF THE LOG-LINEAR WIND PROFILE IS SHOWN TO BE SMALL. THE VARIANCE AND SPECTRUM OF THE VELOCITY COMPONENT AT RIGHT ANGLES TO THE MEAN WIND ARE SUMMARIZED FROM OBSERVATIONS AT 4 DIFFERENT PLACES. THE SPECTRUM OF THE LATERAL VELOCITY COMPONENT CAN BE SEPARATED INTO TWO QUITE DIFFERENT REGIMES: THE MECHANICAL REGIME EXTENDING FROM VERY SHORT WAVELENGTHS TO ABOUT 100 M OR A LITTLE LONGER; AND THE CONVECTIVE REGIME WHICH EXTENDS DOWN FROM SEVERAL KILOMETERS TO BELOW 200 M. THE BREAKDOWN OF SURFACE INVERSIONS AT NIGHT AT BROOKHAVEN IS CLOSELY ASSOCIATED WITH THE OCCURRENCE OF STRONG WINDS ABOVE 300 FT, AND BECOMES ALMOST A CERTAINTY WHEN THE WIND AT 355 FT EXCEEDS 8 M/SEC. THE OCCURRENCE OF TURBULENCE BELOW 400 FT IS SENSITIVE TO THE RICHARDSON NUMBER, WHICH IN THE LAYER FROM 100 TO 300 FT APPEARS TO HAVE A CRITICAL VALUE SLIGHTLY LARGER THAN 0.25

Descriptors :   *WIND, ATMOSPHERES, MEASUREMENT, STATISTICAL ANALYSIS.

Distribution Statement : APPROVED FOR PUBLIC RELEASE