Improved trace gas flux estimation through IRGA sampling optimization

• Published in: Agricultural and forest meteorology 2009-03, Vol.149 (3), p.623-638
• Main Authors: Clement, R.J., Burba, G.G., Grelle, A., Anderson, D.J., Moncrieff, J.B.
• Format: Article
• Language: English
• Subjects: accuracy; Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agronomy. Soil science and plant productions; air; air flow; atmosphere; Biological and medical sciences; carbon dioxide; chemical composition; CO 2 flux; Corrections; data collection; Eddy covariance; eddy covariance method; Environmental Sciences related to Agriculture and Land-use; equipment design; equipment performance; Error; field experimentation; Forest Science; Frequency response; Fundamental and applied biological sciences. Psychology; Förnyelsebar bioenergi; gas exchange; gas flux; General agronomy. Plant production; heat transfer; infrared gas analyzer; IRGA; Latent heat flux; Miljö- och naturvårdsvetenskap; optimization; Renewable Bioenergy Research; samplers; sampling; simulation models; Skogsvetenskap; spectroscopy; Trace gas flux; trace gases
• ISSN: 0168-1923; 1873-2240; 1873-2240
• DOI: 10.1016/j.agrformet.2008.10.008

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.