التفاصيل البيبلوغرافية
| العنوان: |
Lower-cost eddy covariance for CO2 and H2O fluxes over grassland and agroforestry. |
| المؤلفون: |
van Ramshorst, Justus G. V.1,2 (AUTHOR) justus.vanramshorst@uni-goettingen.de, Knohl, Alexander2,3 (AUTHOR), Callejas-Rodelas, José Ángel2 (AUTHOR), Clement, Robert1,4 (AUTHOR), Hill, Timothy C.4 (AUTHOR), Siebicke, Lukas2 (AUTHOR), Markwitz, Christian2 (AUTHOR) |
| المصدر: |
Atmospheric Measurement Techniques. 2024, Vol. 17 Issue 20, p6047-6071. 25p. |
| مصطلحات موضوعية: |
*AGROFORESTRY, *HEAT flux, *EDDIES, *CARBON dioxide, *GRASSLANDS |
| مستخلص: |
Eddy covariance (EC) measurements can provide direct and non-invasive ecosystem measurements of the exchange of energy, water (H2O) and carbon dioxide (CO2). However, conventional eddy covariance (CON-EC) setups (ultrasonic anemometer and infrared gas analyser) can be expensive, which recently led to the development of lower-cost eddy covariance (LC-EC) setups (University of Exeter). In the current study, we tested the performance of an LC-EC setup for CO2 and H2O flux measurements at an agroforestry and adjacent grassland site in a temperate ecosystem in northern Germany. The closed-path LC-EC setup was compared with a CON-EC setup using an enclosed-path gas analyser (LI-7200, LI-COR Inc., Lincoln, NE, USA). The LC-EC CO2 fluxes were lower compared to CON-EC by 4 %–7 % (R2=0.91 –0.95), and the latent heat (LE) fluxes were higher by 1 %–5 % in 2020 and 23 % in 2021 (R2=0.84 –0.91). The large difference between latent heat fluxes in 2021 seemed to be a consequence of the lower LE fluxes measured by the CON-EC. Due to the slower response sensors of the LC-EC setup, the (co)spectra of the LC-EC were more attenuated in the high-frequency range compared to the CON-EC. The stronger attenuation of the LC-EC led to larger cumulative differences between spectral methods of 0.15 %–38.8 % compared to 0.02 %–11.36 % of the CON-EC. At the agroforestry site where the flux tower was taller compared to the grassland, the attenuation was lower because the cospectrum peak and energy-containing eddies shift to lower frequencies which the LC-EC can measure. It was shown with the LC-EC and CON-EC systems that the agroforestry site had a 105.6 gCm-2 higher carbon uptake compared to the grassland site and 3.1–14.4 mm higher evapotranspiration when simultaneously measured for 1 month. Our results show that LC-EC has the potential to measure EC fluxes at a grassland and agroforestry system at approximately 25 % of the cost of a CON-EC system. [ABSTRACT FROM AUTHOR] |
| قاعدة البيانات: |
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