Eddy correlation measurements of CO2, latent heat, and sensible heat fluxes over a crop surface

✍ Scribed by Dean E. Anderson; Shashi B. Verma; Norman J. Rosenberg

• Publisher: Springer
• Year: 1984
• Tongue: English
• Weight: 556 KB
• Volume: 29
• Category: Article
• ISSN: 0006-8314
• DOI: 10.1007/bf00119792

✦ Synopsis

Eddy correlation equipment was used to measure mass and energy fluxes over a soybean crop. A rapid response CO, sensor, a drag anemometer, a Lyman-alpha hygrometer and a fine wire thermocouple were used to sense the fluctuating quantities.

Diurnal fluxes of sensible heat, latent heat and CO, were calculated from these data. Energy budget closure was obtained by summing the sensible and latent heat fluxes determined by eddy correlation which balanced the sum ofnet radiation and soil heat flux. Peak daytime CO, fluxes were near 1.0 mg m-* (ground area) s -r.

The eddy correlation technique was also employed in this study to measure nocturnal CO, fluxes caused by respiration from plants, soil, and roots. These CO, fluxes ranged from -0.1 to -0.25 mg m-a s-'.

From the data collected over mature soybeans, a relationship between CO, flux and photosynthetically active radiation (PAR) was developed. The crop did not appear to be light-saturated at PAR flux densities < 1800 uEi m-a s -'. The light compensation point was found to be about 160 uEi m -* s -'.