Quantifying gas emissions through vertical radial plume mapping with embedded radial basis function interpolation

Abstract

The Vertical Radial Plume Mapping (VRPM) method proposed by the U.S. EPA in Other Test Method 10 (OTM-10) is widely used to measure nonpoint source emissions. However, the accuracy of the VRPM is affected by the large number of parameters relative to the measurement data and the presence of measurement noise. To improve the accuracy of flux estimation, we propose to apply evenly spaced radial basis function (RBF) interpolation to the measurement data before using the VRPM. The experiment was tested and validated under various measurement configurations. The results indicate that RBF interpolation techniques, especially Gaussian RBF (GSRBF) interpolation, reduce the mean absolute error and root mean square error of flux estimation, leading to improved flux estimation accuracy. The mean emission rate calculated after RBF interpolation is closer to the true value, indicating that this interpolation technique helps to reflect more accurately the average emission level over time. Even in the most challenging validation set, the percentage error of mean flux decreased by 3.8% after interpolation. The proposed method can be a simple and measurement-cost-effective way to improve the accuracy of VRPM measurements.