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The effect of vertical line averaging on the spectra of temperature and heat‐flux
Author(s) -
Kaimal J. C.
Publication year - 1968
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49709440004
Subject(s) - anemometer , wind speed , line (geometry) , coherence (philosophical gambling strategy) , heat flux , spectral line , flux (metallurgy) , coherence length , horizontal line test , mechanics , temperature measurement , physics , heat transfer , geodesy , optics , mathematics , meteorology , geology , materials science , geometry , thermodynamics , statistics , superconductivity , quantum mechanics , astronomy , metallurgy
The paper describes an attempt to evaluate the effects of vertical line averaging on temperature statistics by using simultaneous measurements from sensors of different lengths. Results show that the transfer function for vertical line averaging derived by Gurvich for the vertical velocity component applies also to temperature spectra. Heat‐flux, when computed with vertical velocity measurements from a sonic anemometer, is relatively insensitive to line averaging (at least up to 80 cm at 9 m height). But the coherence between the line average and its mid‐point value shows consistent behaviour only for short line lengths of the order of 20 cm. With longer lengths the coherence is likely to vary from one run to another depending on mean wind speed.