Observing Earth critical zone processes in the Bayelva basin (CZO@Bayelva). Data represents the average values and the corresponding standard deviation of Net Ecosystem Exchange (NEE), Ecosystem Respiration (ER) and Gross Primary Productivity (GPP) obtained from two different sites in the tundra of the Bayelva river basin: One site (named CZ) is located in the vicinity of the Climate Change Tower. The other one (named "Airport") is in the vicinity of the Ny Alesund Airport. Each average value is obtained as a mean over a set of around 20 point measures for each plot and each sampling date. Flux data are complemented by measurements of soil temperature, soil volumetric water content, air temperature and relative humidity, and solar irradiance. CO2 fluxes are measured using a flux chamber and a LI-COR IRGA by means of the Dynamic Flux Chamber method.

The column water vapor or Precipitable Water Vapor (PWV) is measured at Thule Air Base (76.5°N, 68.8°W), Greenland, by means of a ground-based millimeter-wave spectrometer (GBMS) installed at 220 m a.s.l. The GBMS observes rotational lines of atmospheric molecules emitting between 230 and 280 GHz, with a spectral pass band of 600 MHz. The PWV is calculated from direct measurements of atmospheric opacity (tau) at the indicated frequencies by using the linear relation PWV = a+tau*b, where a and b depend only on frequency. Measurements have a temporal resolution of 15 minutes and are carried out continuously when the GBMS is operated.