Explanation to the data files submitted by V. Romanovsky. All data are from Ivotuk, North Slop of Alaska. Coordinates and short description of sites are in the files headings. Temperatures are in C, soil moisture is shown as volumetric water content (m3/m3). 1) Files IvotukMAT9899 and IvotukMAT9900: Measured every 5 min and daily averaged (from midnight to midnight) data at the Moist Acidic Tundra site: Column E - Air temperature at ca 1.6 meters above ground surface Column F - Ground surface (interface between the ground and the atmosphere) temperature (1 cm below the surface) Columns from G to L - air/snow temperatures at different elevations above the ground surface (elevations are shown in line 10) Columns from M to Q - Soil temperatures at different depths (depths are shown in line 10) Please, ignore column R Columns S to V - Soil moisture (volumetric water content) at 0.15 m, 0.25 m, 0.45 m and 0.65 m depths. 2) Files IvotukMNT9899 and IvotukMNT9900: Measured every 5 min and daily averaged (from midnight to midnight) data at the Moist Non-Acidic Tundra site: Column E - Air temperature at ca 1.6 meters above ground surface Column F - Ground surface (interface between the ground and the atmosphere) temperature (1 cm below the surface) Columns from G to K - air/snow temperatures at different elevations above the ground surface (elevations are shown in line 10) Columns from L to S - Soil temperatures at different depths (depths are shown in line 10) Please, ignore column R Columns T to V - Soil moisture (volumetric water content) at 0.11 m, 0.26 m and 0.43 m depths. 3) Files IvotukMOSS9899 and IvotukMOSS9900: Measured every 5 min and daily averaged (from midnight to midnight) data at the Moss Moist Acidic Tundra site: Column E - Air temperature at ca 1.6 meters above ground surface Column F - Ground surface (interface between the ground and the atmosphere) temperature (1 cm below the surface) Columns from G to L - air/snow temperatures at different elevations above the ground surface (elevations are shown in line 10) Columns from M to S - Soil temperatures at different depths (depths are shown in line 10) Please, ignore column R Columns T to V - Soil moisture (volumetric water content) at 0.16 m, 0.28 m and 0.39 m depths. 4) Files IvotukShrub9899 and IvotukShrub9900: Measured every 5 min and daily averaged (from midnight to midnight) data at the Shrub Tundra site: Column E - Air temperature at ca 1.6 meters above ground surface Column F - Ground surface (interface between the ground and the atmosphere) temperature (1 cm below the surface) Columns from G to J (from G to K for IvotukShrub9900) - air/snow temperatures at different elevations above the ground surface (elevations are shown in line 10) Columns from K to Q (from L to Q for IvotukShrub9900) - Soil temperatures at different depths (depths are shown in line 10) Please, ignore column R Columns S to U - Soil moisture (volumetric water content) at 0.1 m, 0.21 m and 0.38 m depths.