Weather data has been collected at Toolik Lake by a Campbell 21x datalogger since June 1988. 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 unfrozen 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. Net radiation and pan evaporation are only measured during the summer months. The hourly data are in the file 99DLTLH.DAT, the three hourly data are in 99DLTLO.DAT, and daily summaries are in 99DLTLD.DAT. A second Campbell 21x datalogger 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 full description of the sensors and site is in file SENSORS.DOC. The original data is in file 99DLTDAT.ZIP, which is archived at The Marine Biological Lab, Woods Hole, MA.

Notes: Wind speed less than .447 is considered calm.
Radiation data was not totaled for the winter months since no attempt was made to keep sensors snow and frost free. Lake temperature is measured near the lake depth sensor. Therefore the lake depth measurements give the depth at which lake temperature is measured.

Sampling Description.

VAPOR PRESS 5M:
Daily average of the following hourly calculation.
If Air Temp > 0 then (RH 5M/100) * 6.1121 * exp(17.368 * AIR TEMP 5M/(238.88 + AIR TEMP 5M))
If Air Temp < 0 then (RH 5M/100) * 6.1121 * exp(17.966 * AIR TEMP 5M/(238.88 + AIR TEMP 5M))
(Buck 1981).
PYR J CM2 : Daily sum of PYRANOMETER * 0.3600 jcm2 * 1000 Watt/Kwatt
QUANTUM Mol/m2: (Daily sum of Quantum)*60sec*60 min* 10^-6 umol/mol