CO₂ - Temperature Gradient chamber

This is another facility to study the effects of global warming, it both halps in maintaining higher CO₂ concentrations and warmer conditions simultaneously because they are essential environmental factors for all plants.

The chamber was first time designed and built at the Terrestrial Environment Research Center at the University of Tsukuba (36.1^oN, 140.1^o E), Japan in 1996-97. The chamber is constructed from a commercial free-standing green-house tunnel. The framework consists of a series of semicircular zinc coated support pipes and connected by pipe joints. The frameworks are covered with UV transparent PVC film through which 85% radiations passes.

The air in the chamber is naturally heated by incident solar radiation; the temperature gradient is created by flowing air from the air inlet to the outlet. In order to achieve the target temperature difference between the air inlet and outlet. The ventilation rate is controlled according to the fluctuation of air temperature caused by changes in the incident solar radiation.

The ventilation rates are adjusted every 10s through digital signals from a personal computer by applying a PID control algorithm based on the temperature measured 10cm above the canopy. The flow direction changer of CO₂ and temperature is maintained during the night or during low incident solar radiation conditions such as a cloudy day.

CO₂ is supplied through longitudinal pipe along the inside wall of CTGC. During night CO₂ concentration is normally higher due to respiratory CO₂ from plants and soil.

All data set of temperatures and CO₂ concentration in the chamber is monitored individually every 10s and averaged over 5 min intervals. The controller/data logger systems are operated by specially designed software using windows platform.