Improved trace gas flux estimation through IRGA sampling optimization

We examine the theoretical and practical aspects of improving the sampling methods of spectroscopic trace gas sensors of Eddy covariance flux measurement systems. Theory is developed based on non-ideal ventilation devices and existing equations for tube flow and attenuation of non-reactive trace gases and temperature. Model results indicate an optimum design exists which can be expressed in relation to intake tube diameter and which depends upon the ventilation device employed. Field experiment results (employing modified open path IRGAs) show that the use of short intake tubes can reduce flux losses by trace gas signal attenuation while minimizing the adjustments required for density fluctuations, with additional benefits of increased data capture under adverse environmental conditions. (C) 2008 Elsevier B.V. All rights reserved.