Arctic Tundra Ecosystems Global Change Research Group San Diego State University Principal Investigator - Dr. Walter C. Oechel Department of Biology 5500 Campanile Drive San Diego, CA 92182 Phone: (619) 594-6613 Fax: (619) 594-7831 SITE LOCATIONS Barrow site (71 19' 21.00" N : 156 37' 18.53" W) is located adjacent to the National Oceanic & Atmospheric Administration's Climate Monitoring and Diagnostics Laboratory (NOAA-CMDL). The area is composed of several different representative wet-moist coastal sedge tundra types. Atqasuk site (70 28' 10.6" N : 157 24' 32.2" W) is located 100 km south of Barrow, Alaska, and adjacent to the native village of Atqasuk. Soils are developed on aeolian sands of Quaternary age. The site is comprised of a variety of moist-wet coastal sedge tundra, and moist-tussock tundra surfaces in the more well-drained upland. UPAD site (70 16' 53.5" N : 148 53' 05.4" W) is located on the Prudhoe Bay, Alaska, oilfield. The vegetation is a mixture of moist and wet coastal sedge tundra. The three sites measure year-round CO2 and H2O fluxes and energy fluxes. INSTRUMENTATION The eddy correlation measurement system provides in situ 10Hz data of CO2, H2O, sensible heat and latent heat fluxes using a three-dimensional Gill (R3) ultrasonic anemometer/thermometer with an open-path CO2/H2O (NOAA-ATDD) infrared analyzer. These 10Hz data are then averaged every 30minutes to obtain half-hourly flux estimates of mass, momentum and energy. Additional, meteorological variables such as net radiation, photosynthetically active radiation (PAR), ground heat flux, air temperature, relative humidity, soil temperature and precipitation are measured and stored as 30-min averages (precipitation as accumulated half hour totals). DATA FORMAT Variable List (Symbols and Units) The file is in ASCII comma -elimited text format. Missing values are represented by "-9999". No data collected are represented by "N/A". Disclaimer: Data processed in 1999 have to be considered preliminary and these estimates could change considerably and without notice. Please contact us if you plan to use our data, and we reserve the right to co-authorship if deemed appropriate. Symbol Description Instrument Unit YY Year JD Julian Day TM Time Rn Net Radiation Q-7 (REBS) W m-2 LE Latent Heat Flux ATDD/NOAA Open W m-2 Open-Path IRGA W m-2 H Sensible Heat Flux Sonic Anemometer W m-2 G_1 Soil Heat Flux HFT-3 (REBS) W m-2 G_2 Soil Heat Flux HFT-3 (REBS) W m-2 PAR Photosynthetically LI-190SB (LI-COR) ?E m-2 s-1 Active Radiation Air T Air Temperature at HMP 35C (Vaisala) oC Soil T1_0 Soil Temp at 0 cm Type-T Thermocouple oC Soil T1_5 Soil Temp at -5cm Type-T Thermocouple oC SoilT1_10 Soil Temp at -10 cm Type-T Thermocouple oC Soil T2_0 Soil Temp at 0 cm Type-T Thermocouple oC Soil T2_5 Soil Temp at -5 cm Type-T Thermocouple oC SoilT2_10 Soil Temp at -10cm Type-T Thermocouple oC RH Relative Humidity HMP 35C (Vaisala) % Rain Precipitation TE525 (Texas Elect) mm WD Wind Direction Sonic Anemometer o (True) WS Wind Speed Sonic Anemometer m s-1 u* Friction Velocity Sonic Anemometer m s-1 FCO2 CO2 Flux ATDD/NOAA Open-Path mg m-2 s-1 IRGA FH2O H2O Flux ATDD/NOAA Open-Path mg m-2 s-1 IRGA