In the framework of the two projects, CEOP-AEGIS ( FP7 Topic ENV.2007.4.1.4.2) and TiP (DFG SPP 1372), a Krypton Hygrometer (KH20) was installed at the Eddy- Covariance complex at the Nam Co Comprehensive Observation and Research Station of the Chinese Academy of Science (CAS), at Nam Co, Tibet, China in 4700m. The experiment started on Sunday, February 14th, 2010 with the purpose to measure the latent heat flux under low water vapor conditions. In regions like the Tibetan Plateau, the Arctic or Antarctica the absolute humidity content of the atmosphere drops to values below 2 or even 1 g m-3. Since data collected by scientists from the Institute for Tibetan Plateau research showed inconsistencies in the humidity measurements with the standard LiCor 7500 the additional KH20 was installed and a new calibration system for the KH20 was tested. This calibration unit works with a variable path length, and can therefore be used for easy in situ calibration of the KH20 while the calibration of the LiCor 7500 is more complex. The data collected in the side by side measurement with the two different humidity sensors will be used to improve the measurements of the latent heat flux. The experiment is conducted in close cooperation with the Institute of Tibetan Plateau research.
From left to right: The scientists during the experiment at Nam Co, the measurement setup and the KH20 Calibration Unit.