A 46-m, self-supporting tower with associated lab building, power, and communication lines was completed in June, 1998. At the end of June and in July 1998 the instrument booms, data loggers, communication and gas-flow lines, and the eddy correlation and radiation sensors were installed on the two main observation levels of the tower (46 m and 34 m, see the schematic representation of the tower set-up, below). The flow control system was installed in September and data collection on the top level started on September 22, 1998. The profile measurements of mean temperature, humidity and CO2 concentration through the canopy and up to the 46 m level on the tower was completed in March, 1999. Operations of the Ameriflux towers. Data quality, site instrumentation, site data collaborations.