Experimental Design/Sampling Description:
Weather data at Toolik Lake has been collected by the Arctic LTER 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 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 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 yyyyDLTDAT.ZIP, which is archived at The Marine Biological Lab, Woods Hole, MA.

Notes and Comments:
Wind Speeds less than .447 are considered calm. For the global solar radiation and photosynthetically active radiation sensors no attempt is made to correct for frost or snow on the sensors during the winter months. Therefore winter radiation data should be view as suspect and used only qualitatively. August 1998 August 2006 the tipping rain gage was fitted with a Campbell CS705 adapter for measuring snow. A Wyoming windshield was build for the precipitation gage 30Aug99. In August 2006 a OTT Pluvio Precipitation Gauge. (Standard with a heating ring. Resolution: 0.01/0.1; Collecting area 200 cm2; Total quantity 250 mm) replaced the tipping rain gauge/CS705 adapter.

On 12June2006 replace the Vaisala barometer with a Setra 278 Barometric Pressure Sensor. Changed Barometric output from mmHg to millibar for all of 2006. Will send in the Vaisala for recalibration.

Data was lost during the winter of (2005-2006 31Dec05 – 20Apr06) when a storage module filled up.
From 15May06 to 5June06 Temperature, wind and radiation sensors were taken off line to avoid mud splatter when a well was drilled near by

See additional notes under Comments variable.

CALCULATIONS
variable Formula
DAYS : JULIAN + (HOUR/2400)
VAPOR PRESS 5M: 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).
TOTAL J CM2 HR: PYRANOMETER * 0.3600 jcm2 * 1000 Watt/Kwatt