Uncertainties of Derived Dewpoint Temperature and Relative Humidity

Abstract

This paper presents an evaluation of derived dewpoint temperature and derived relative humidity, in which the dewpoint temperature is calculated using measured ambient air temperature and measured relative humidity variables and the derived relative humidity is calculated from measured dewpoint temperature. The derived dewpoint temperature and relative humidity are calculated using algorithms provided by the World Meteorological Organization. The method of uncertainty analysis, provided by the National Institute of Standards and Technology, is applied to calculate the uncertainties of an indirect measurement of derived dewpoint temperature and derived relative humidity. The results from the uncertainty analyses of derived and observed variables suggest that the use of derived dewpoint temperature and derived relative humidity involves risk because the uncertainties of modern dewpoint temperature and relative humidity sensors can create several degrees Celsius of error in the derived dewpoint temperature and several percent in the derived relative humidity.