A New Tool for Automated Data Collection and Complete On-site Flux Data Processing for Eddy Covariance Measurements

Abstract:

The eddy covariance method is widely used for direct measurements of turbulent exchange of gases and energy between the surface and atmosphere. In the past, raw data were collected first in the field and then processed back in the laboratory to achieve fully corrected publication-ready flux results. This post-processing consumed significant amount of time and resources, and precluded researchers from accessing near real-time final flux results.

A new automated measurement system with novel hardware and software designs was developed, tested, and deployed starting late 2013. The major advancements with this automated flux system include:

1) Enabling logging high-frequency, three-dimensional wind speeds and multiple gas densities (CO₂, H₂O and CH₄), low-frequency meteorological data, and site metadata simultaneously through a specially designed file format

2) Conducting fully corrected, real-time on-site flux computations using conventional as well as user-specified methods, by implementing EddyPro Software on a small low-power microprocessor

3) Providing precision clock control and coordinate information for data synchronization and inter-site data comparison by incorporating a GPS and Precision Time Protocol.

Along with these innovations, a data management server application was also developed to chart fully corrected real-time fluxes to assist remote system monitoring, to send e-mail alerts, and to automate data QA/QC, transfer and archiving at individual stations or on a network level.

Combination of all of these functions was designed to help save substantial amount of time and costs associated with managing a research site by eliminating the post-field data processing, reducing user errors and facilitating real-time access to fully corrected flux results. The design, functionality, and test results from this new eddy covariance measurement tool will be presented.