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TitleThe propagation of uncertainty for humidity calculations
Publication TypeJournal Article
Year of Publication2009
AuthorsLovell-Smith, J.
Pagination607 - 615
Date Published2009
ISSN00261394 (ISSN)
KeywordsAtmospheric humidity, Controlling equation, Dewpoint, Humidity control, Input variables, Meteorological instruments, Mixing ratios, Moisture, Moisture meters, National metrology institutes, Relative humidities, Sensitivity coefficient, Uncertainty calculations, Water vapor, Water vapour, Wet-bulb
AbstractThis paper addresses the international humidity community's need for standardization of methods for propagation of uncertainty associated with humidity generators and for handling uncertainty associated with the reference water vapour-pressure and enhancement-factor equations. The paper outlines uncertainty calculations for the mixing ratio, dew-point temperature and relative humidity output from humidity generators, and in particular considers controlling equations for a theoretical hybrid humidity generator combining single-pressure (1-P), two-pressure (2-P) and two-flow (2-F) principles. Also considered is the case where the humidity generator is used as a stable source with traceability derived from a reference hygrometer, i.e. a dew-point meter, a relative humidity meter or a wet-bulb psychrometer. Most humidity generators in use at national metrology institutes can be considered to be special cases of those considered here and sensitivity coefficients for particular types may be extracted. The ability to account for correlations between input variables and between different instances of the evaluation of the reference equations is discussed. The uncertainty calculation examples presented here are representative of most humidity calculations. © 2009 BIPM and IOP Publishing Ltd.

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