Design and construction of a closed path eddy covariance system

• Main Author: Hu, Ezra Jia Ming
• Other Authors: Fei Duan
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/68784
• Institution: Nanyang Technological University

Eddy Covariance has been an effective way to quantify changes in carbon fluxes within the ecosystem and has been largely employed by many scientific institutions. However it is largely daunted with challenges requiring precise set up to ensure flux data obtained are accurate, with the main being the loss of Eddie fluctuations through frequency attenuation. Most closed path eddy covariance setup have generally been done in easily accessible locations over short distances with few being conducted in a forested area with low power supply. This report will first serve to show the motivations behind the system design and the selection of materials through optimization methods to achieve the requirements of low power and low frequency attenuation across a 65m tower based on theoretical assumptions. Attenuation have been said to be reduced through achieving turbulent flow where Reynolds number > 2300. Such flow rates are said to be adequate in providing good frequency response for flux data collections. However experimental results show that relying solely on flow rate seems to be inadequate, achieving half power frequency as low as 0.35Hz whereas setups with force turbulence were able to achieve half power frequency as high as 2.5Hz. It seems that it is necessary to look further into turbulent inducing methods while still complying with the power and pressure constraints.