Uncertainty evaluation for aneroid barometer measurement. Part I. “Guide to the expression of uncertainty in measurement method”

Addressing the oversight in the evaluation of measurement uncertainty for traditional aneroid barometers, where the performance of calibration equipment (in particular, the temperature coefficient calibration box, henceforth termed the coefficient box, and the indication calibration box, referred to as the indication box) and the uncertainty associated with the temperature coefficient are frequently neglected, this paper introduces an enhanced evaluation framework. The objective of this framework is to achieve a more precise evaluation of measurement uncertainty and to enhance the accuracy of calibration outcomes. Initially, a comprehensive calibration methodology is devised, accounting for the impact of the coefficient box's performance on the temperature coefficient and the influence of the indication box's performance on the indication error. By executing this methodology, detailed empirical test data are procured. Subsequently, incorporating various factors that affect the measurement outcomes, the measurement uncertainty is evaluated utilizing the collected data. The evaluation results reveal that the uncertainty of the temperature coefficient is U = 0.004 hPa/°C (k = 2), and the uncertainty of the indication error is U = 0.12 hPa (k = 2). For comparison, the traditional calibration approach yields an uncertainty of the temperature coefficient of U = 0.004 hPa/°C (k = 2) and an uncertainty of the indication error of U = 0.09 hPa (k = 2). Through a comparative analysis, it is evident that the coefficient box's performance has little effect on the temperature coefficient's uncertainty; however, neglecting the performance of the indication box and the temperature coefficient's uncertainty can result in the evaluation of the indication error's uncertainty deviating from actuality. Consequently, it is recommended that the effects of the indication box's performance and the temperature coefficient's uncertainty be thoroughly considered when evaluating the measurement uncertainty of an aneroid barometer's indication error. By doing so, more authentic and reliable evaluation results can be obtained, ultimately enhancing the accuracy of the aneroid barometer's calibration outcomes.