Keywords: Eddy Covariance Sonic IRGA.jpg Semi open path eddy covariance system consisting of an ultrasonic anemometer to measure 3D air flow and infrared gas analyser IRGA to measure carbon dioxide This system is situated at the top of a 20 metre high tower above a forest Digital photo taken by me Veedar in 2006 en wikipedia Calliopejen1 CommonsHelper 2006 Veedar wikipedia en Veedar Original upload log page en wikipedia Eddy_Covariance_Sonic_IRGA jpg 2007-06-25 12 12 Veedar 872×910× 402587 bytes <nowiki>Digital photo taken by me Veedar in 2006 of a semi open path eddy covariance system consisting of an ultrasonic anemometer to measure 3D air flow and infrared gas analyser IRGA to measure carbon dioxide This system is situated at the top of a 20 me</nowiki> Anemometers Measuring instruments air pollution |