Measuring system for the long‐term monitoring of biosphere/atmosphere exchange of carbon dioxide

Authors:
Publisher website
Google Scholar
Abstract
We describe an ongoing program being carried out in Hungary to investigate the role of the temperate continental region in the global carbon cycle. Carbon dioxide mixing ratios are continuously monitored at 10, 48, 82, and 115 m above the ground on a television transmitter tower, and the atmosphere/surface exchange of CO2 is measured by eddy covariance at 82 m. The region surrounding the tower is typical of rural areas of central Europe, with agricultural fields, forest patches, and small villages. We first describe the layout and the operation of the measuring system designed for the continuous, unattended monitoring of the vertical distribution of CO2 mixing ratio in the lowest 115 m of the atmosphere based on a Li‐Cor model 6251 infrared gas analyzer (IRGA). It provides vertical profile data with a temporal resolution of 8 min. Next, we discuss the measuring system for long‐term, continuous monitoring of the biosphere/atmosphere exchange of CO2. The eddy correlation system is based on a Li‐Cor model 6262 fast‐response IRGA and a Gill ultrasonic anemometer running at 4 Hz sampling frequency. Results are to illustrate the performance of the systems. Among others, they show the occasional accumulation of CO2 in the boundary layer in the Carpathian Basin during winter and the diurnal variation of the vertical distribution of CO2 mixing ratio in summer. A simple method based on similarity theory to calculate vertical fluxes from vertical gradients is presented, which can be used to fill the data gaps that inevitably occur during long‐term eddy correlation measurements. The present study confirms the feasibility of the long‐term tall‐tower CO2 flux and mixing ratio measurements.

This publication has 54 references indexed in Scilit: