Gas exchange associated with the coherent air motion within a forest.

The coherent air motion in and above forest canopy is studied based on the field experiments。The experiments were carried out on a23m tower in a coniferous forest of about15m。A3 m arm which turns along the wind direction and have fast fine wire thermocouples at both ends was developed to measure the size and translation velocity of the organized motion.The same fine wire thermocouples were installed at5different heights on the tower.A3-D sonic anemometer and an open pass gas analyzer were installed at the top of the tower.The field observation was made during fine days in summer and autumn.The observed coherent organized motions were practically buoyant plumes.They were convective elements which extends vertically.They were found to have a scale of about10s to 100s meters and to travel with speed greater than the wind speed at the measured height.The organized motion interpenetrated considerably deep into the forest canopy.This organized convective motion was found to play a important rolls in transporting CO I D 22个D 2 and water vapor.

The coherent air motion in and above forest canopy is studied based on the field experiments. The experiments were carried out on a 23m tower in a coniferous forest of about 15m. A 3m arm which turns along the wind direction and have fast fine wire thermocouples at both ends was developed to measure the size and translation velocity of the organized motion. The same fine wire thermocouples were installed at 5 different heights on the tower. A 3-D sonic anemometer and an open pass gas analyzer were installed at the top of the tower. The field observation was made during fine days in summer and autumn.The observed coherent organized motions were practically buoyant plumes. They were convective elements which extends vertically. They were found to have a scale of about 10s to 100s meters and to travel with speed greater than the wind speed at the measured height. The organized motion interpenetrated considerably deep into the forest canopy. This organized convective motion was found to play a important rolls in transporting COィイD22ィエD2 and water vapor.