EXPERIMENTAL DESIGN AND METHODS: Weather data at Toolik Lake has been collected by the Arctic LTER since June 1988. The station is located about 50 meters south of the lake's edge in a sedge/moss (Tomenthypnum nitens-Carex bigelowii) vegetation. Sensors that are measured every minute and averaged or totaled every hour include: air temperature and relative humidity at 1 and 5 meters, wind speed at 1 and 5 meters, wind direction at 5 meters, global solar radiation, photosynthetically active radiation, barometric pressure, and precipitation. Sensors measured every 10 minutes and averaged every three hours include: soil temperatures, lake temperature, lake depth, and evaporation pan depth and pan water temperature. Pan evaporation are only measured during the summer months. The hourly data are in the file yyyyDLTLH.DAT, the three hourly data are in yyyyDLTLO.DAT, and daily summaries are in yyyyDLTLD.DAT.
A second datalogger, Toolik Moist Acidic Tussock station, about 700 meters from the main weather station logs air and soil temperatures and photosynthetically active radiation in the experimental treatment plots. Treatments include greenhouse, shading, and fertilization. In the control plot wind speed and direction, global solar radiation and unfrozen precipitation are also measured. This station is also used as a backup to the main weather station.
The Imnavait weather station, 12 kilometers away and 200 meters higher, is also used to fill in data gaps. Regressions of summer air temperature between Imnavait and with Toolik are good but during the winter months there is greater variability. This station is maintained by Larry Hinzman and Doug Kane, Water Research Center; University of Alaska Fairbanks; Fairbanks, AK 99775-5860. Precipitation data from the Natural Resources Conservation Service (NRCS) Alaska Imnavait weather station is also used to fill in the data gaps. Please contact Rick McClure, Data Collection Officer, Natural Resources Conservation Service, 949 E. 36th Ave., Suite 400,, Anchorage, AK 99508-4362, (907) 271-2424 for more details.
The full description of the sensors and site is in file SENSORS.DOC. The original data is in file yyyyDLTDAT.ZIP which is archived at The Marine Biological Lab, Woods Hole, MA.

NOTES AND COMMENTS: Wind speed less than .447 is considered calm.
Radiation data were not totaled for the winter months since no attempt was made to keep sensors snow and frost-free. Lake temperature is measured at the lake depth sensor. Therefore the lake depth measurements give the depth at which lake temperature is measured. See additional notes under Comments variable.

On August 19-20, 2008 - the weather station underwent an upgrade to the main data logger to a Campbell CR3000. Wind speed at 1 m was removed; Wind speed at 5m was replaced Vaisala HMP45C. Pyranometer was replaced w/ Kipp and Zonen CMP6 (ventilation unit - year round numbers are now available). Temperature/RH at 1 m was removed and replaced w/ an RMYoung T/RH probe at 3 m.

NOTE:!!! ************************

There appears to be an offset between the Viasala at 5 meters and the RMYoung Temperature at 3 meters. This still needs more testing.

All wind direction after August 19th was replaced with wind direction from the Moist Acidic site station. There was programming error where the wind direction was only sampled once an hour. This was not corrected until summer 2010.

All winter precipitation was deleted. The sensor was recording many false readings during the winter months.

Jim Laundre Oct 27, 2010