Note: These data are provisional and not error checked!

Weather station time is set to Alaska standard time and is not adjusted for daylight savings. Data are hourly averages (air temperature, lake level, lake temperature, wind speed), sums (rain, radiation) or mean wind vector direction.

Contact with any questions, comments, or requests regarding Toolik metstation data.


Note: These data are provisional and not error checked!

Contact with any questions, comments, or requests regarding Toolik metstation data.


1 Note: During the snow-free season, plant growth may cause small positive snow depth values.

Weather Monitoring at Toolik Field Station

Weather data has been collected at Toolik Field Station (68 degrees 38'N, 149 degrees 36'W) since June 1988. The weather station located at the field station was originally installed by the Arctic LTER ( and TFS assumed control of the station in 2007. The field station is an ideal location for maintaining long-term weather data, as it is located in a data sparse region and adds a data point along the north-south transect of the Northslope of Alaska, following along the Dalton Highway. There is year round access and a long-term pre-existing dataset. These advantages make it possible to provide quality data - a often difficult achievement in remote northern latitudes in Alaska.

To access the historical data from this weather station, please refer to Weather Data Query.

Data collected includes air temperature, relative humidity and wind speed, wind direction, global solar radiation, photosynthetically active radiation, barometric pressure, precipitation, soil temperatures, lake temperature, lake depth, precipitation and evaporation pan depth and pan water temperature. Most sensors are read every minute and then averaged or totaled every hour. The exceptions are soil temperatures, lake temperature, lake depth, and evaporation pan depth and pan water temperature which are read on ten minute intervals and averaged every three hours. Pan evaporation and pan water temperature are only measured during the summer months. For photosynthetically active radiation sensor no attempt is made to correct for frost or snow on the sensors during the winter months. As of 2008, global solar radiation sensor is equipped with a heater and ventilation system to remain snow and frost free throughout the year. Years prior to 2008, the global solar radiation was not kept free from frost or snow. Please note this when viewing radiation data.

In 2011, a new RM Young "Alpine" anemometer was installed by Polar Field Services (CH2M Hill Polar Services). The anemometer is located on a 44'-tall mast and records wind data at 30-sec. intervals. To access these data, please go to

For other weather data in the area, please see the NWS weather data viewer found here.

Contact with any questions, comments, or requests regarding Toolik metstation data.

Annual Met Data Reports
Parameters Measured

Hourly: Readings taken every 30 sec and averaged or totaled every hour

  • Air temperature at 3 m and 5 m (°C)
  • Relative humidity 3 m and 5 m (%)
  • Wind speed at 5 m (from 3 different anemometers, m/s)
  • Wind direction at 5 m (from 3 different anemometers, degrees)
  • Barometric pressure (mbar)
  • Pyranometer: Global solar radiation (sky + sun - J/cm2/hr)
  • Four component net solar radiation (short and long wave incoming and outgoing, W/m2)
  • Diffuse solar radiation (W/m2)
  • Photosynthetically active radiation (PAR quantum - μmol/m2/s)
  • UV-A and UV-B (W/m2)
  • Lake PAR (μmol/m2/s)
  • Snow depth (m)

3-hourly: Readings taken every 10 min and averaged or totaled every 3 hours

  • Soil temperature (duplicates - °C) at surface and at 5, 10, 20, 50, 100, and 150cm depths
  • Lake temperature (single depth)
  • Lake water level (cm)
  • Evaporation pan depth (mm)

Daily averages: Daily averages or min/max measured from all sensors are complied and reported

  • Daily max air temp (°C)
  • Time of day for max air temp
  • Daily min air temp (°C)
  • Time of day for min air temp
  • Daily max wind speed (prop anemometer 1) (m/s)
  • Time of day max wind speed
  • Daily min wind speed (prop anemometer 2) (m/s)
  • Time of day min wind speed
  • Daily min wind speed (sonic anemometer) (m/s)
  • Time of day min wind speed


  • Vaisala HMP155A measures air temperature and relative humidity ( With a 41005-5 14 plate radiation shield (
    • Height: 3 and 5 m
    • 06/03/19: swapped with calibrated sensors
    • 06/06/18: swapped with calibrated sensors
    • 05/01/17: swapped with calibrated sensors
    • 06/08/16: swapped with calibrated sensors
    • 08/28/14.Installed: 3m and 5m


  • Vaisala HMP45C measured air temperature and relative humidity (
    • Height: 5m
    • 08/28/15 swapped with calibrates sensor
    • 05/2013: swapped with calibrated sensor
    • 08/08/11: swapped with calibrated sensor
    • 08/28/09: swapped with calibrated sensor
    • 08/19/08: Installed
  • R.M. Young 41382VC measured air temperature and relative humidity (
    • Height 3m
    • 04/18/12: Swapped with calibrated sensor  (measures in Celsius)
    • 08/08/11: Swapped 3m with calibrated sensor (measures in Fahrenheit- converted to C in logger program)
    • 08/19/08: Installed
  • CS500 measured air temperature and relative humidity (
    • Height 5m
    • 08/19/08: removed
  • 1m Temp/RH removed 08/19/08


  • OTT Pluvio 2 measures "year round precipitation" ( Surrounded by a double fence Wyoming wind shield.
    • performed guided accuracy test: 8/23/16
    • not working: to 6/8/16-8/23/16. Our summer tipping bucket was able to cover that outage, however two snow events occurred during the outage of the year-round gauge, the timing and volume of these events were likely not measured accurately by the tipping bucket.
    • Installed: 08/18/10
  • TE525WS measures "rainfall- tipping bucket" ( Surrounded by a single alter shield.
    • June 4, 2019: repaired wires, was not working for at least several weeks
    • Checked level: 06/06/18
    • 2016: Snow events occurred on June 5th, 8th, and 21st. The exact timing and volume of these events were not measured accurately.
    • Calibrated: 06/09/16


  • OTT Pluvio 250 mm with ring heater removed
    • 09/22/12 - 05/04/13(this date could be wrong): reinstalled
    • 08/18/10: removed


  • FT technologies FT472 heated 2D sonic anemometer measure wind speed and direction ( installed new sensor at 5m.  Since it can be heated should help address data loss from rime icing

  • R.M. Young 5106 measures wind speed and direction. (
    • Note: During winter the sensors are affected by rime ice that prohibits the propellers from spinning at low wind speeds.  Rime can only build up when there is very little wind, so it is difficult to know if they are reporting low or zero wind speeds due to ice or actual conditions.  However, a best attempt was made to replace steady zero values with NAN.
    • Height: 5 m
    • 2019 June: Installed FT472 2D sonic anemometer, other 2 anemometers were leveled and checked for 0deg North reading.
    • 2016 data comes from the R.M. Young 5103 because it provides a more complete data-set. Readings from the instruments are nearly identical.
    • 06/08/16: swapped new 5108-45 for the 5106. crossarm was out of level, now level and more secure.
    • Installed: 06/02/15 new.  (an R.M. Young 5103 was installed at the same time also at 5 m. Its data is available upon request but for 2015 is not output through this website)


  • Met One 024A measures wind direction and Met One 014A measures wind speed (
    • Height: 5m
    • 06/02/2015: both removed
    • 08/28/14: WS and direction sensors swapped with calibrated sensors
    • 08/28/13: WS and direction swapped with calibrated sensors
    • 07/23/13: moved WS and direction sensors to new tower
    • 05/2013: WS and direction sensor swapped with calibrated sensors
    • 08/08/11: WS and direction sensors swapped with calibrated sensors
    • 08/19/08: WS and direction sensors swapped with calibrated sensors
  • 1m WS removed 08/19/08
  • AM25T Thermocouple multiplexer ( with 18 connected omega engineering thermocouples


  • Novalynx 255-100 measures evaporation pan depth (
    • 06/03/19: Evap pan and gage set up, leveled and calibrated for the season
    • 06/06/18: Evap pan and gage set up, leveled and calibrated for the season


  • Novalynx 255-200 evaporation pan (
    • 09/27/07: flipped pan upside down. it was already filled with ice


  • LICOR Quantum LI-190SB measures terrestrial PAR ( There is no heater/ventilator on the PAR sensor, which means data following new snow is inaccurate. If you would like to find and remove that data, we suggest noting the times when there is a large offset between the PAR data to the total solar radiation data.
    • Height: 1.80 m above ground surface
    • 06/03/19: swapped with calibrated sensor (LI-190R)
    • 06/06/18: leveled
    • 06/05/17: leveled
    • 06/09/16: swapped with calibrated sensor
    • 07/23/13: swapped with calibrated sensor
    • 05/2013: swapped with calibrated sensor
    • 08/06/2011: swapped with calibrated sensor
    • 08/29/09: swapped with calibrated sensor
    • Height before 5/16/2013: 1.78 m
  • LICOR Underwater Quantum LI-192SB measures Lake PAR (
    • 09/10/2019: removed for season
    • 07/02/2019: New LI-192SB sensor deployed with an automated wiper system (
    • Height: 1.5m below surface hanging from fixed line/buoy, ~9m from shore and in ~3.5m depth
    • *Will be removed seasonally*


  • Height: 1.3m below surface on 8/26/16- anchored to bottom so height below surface will vary
  • 8/05/17: Sensor failure for remainder of season
  • 8/23/16: swapped with calibrated sensor summers '13,'14,'15,'16 sensor not cleaned of algal growth, affecting measurements. The increase in lake PAR levels immediately following the sensor swap on 8/23/16 is likely due to the sensor being free of algae.
  • 07/23/2013: installed
  • 08/13/07: lowered underwater par from 1.3 to 1.8m
  • 06/14/10 cleaned underwater par
  • 08/12/07: cleaned underwater par of algal growth


  • Yankee Environmental SystemsUVA-1 andUVB-1 measureUVA andUVB radiation (
    • Sept 2019: removed for the season
    • 05/14/19: reinstalled calibrated sensors
    • 06/06/18: leveled both sensors, oriented E to W
    • 08/31/17: leveled both sensors
    • 03/25/16: swapped both sensors with calibrated sensors
    • 04/19/09: Installed (wiring fixed so logging begins 07/1/2010)


  • Delta-T Devices BF5 Sunshine Sensor measures total and diffuse solar radiation ( The BF5 heater/ventilator unit is not as good as the CMP6 or CNR4.  Snow covered periods have been removed.
    • 06/06/18: installed


    • 06/04/17: installed -- 09/23/17: removed

  • Kipp &Zonen CMP6 measures "solar radiation" ( With CVP2 power adapter (?).
    • 06/06/18: leveled, oriented N-S
    • 06/03/17: leveled
    • 08/19/08: Installed
  • Kipp &Zonen CNR4 measureslongwave and shortwave looking up and looking down (  Negative shortwave values at night are an instrument artifact. In order to maintain consistency with historic data, they are left in the record.
    • 10/01/2018: repaired ventilation fan, unsure how long it was broken, was working in mid-Aug 2018.
    • 06/06/18: leveled sensor, oriented N-S
    • 06/07/17: leveled sensor
    • 06/09/16: swapped with calibrated sensor
    • 05/13/13: Installed


  • LICOR Pyranometer LI-200SA measures "Solar Radiation" (
    • 08/19/08: removed
    • 04/30/07: installed


  • CS 107 measures lake temperature (
    • 2019 July 2, co-located with the depth transducer at 306 cm
    • Height: 2m below surface on 8/26/16 - anchored to bottom so height below surface will vary
    • 09/23/17 Sensor moved by 4 cm
    • 07/29/17: Sensor moved by 27 cm
    • 08/28/09: Installed/replaced
    • 08/19/08: Installed 
  • CS420 measures lake depth (
    • 2019 July 2, permanently re-installed at 306cm depth (15.0cm on LTER staff gage).  Data from 2019 will be shifted to match, 2020 will start new depth.  Sensor is installed in pipe mounted to a large concrete anchor in such a way that the sensor can be removed and reinstalled to exact same location if needed for repair or replacement.
    • Height: 2m below surface on 8/26/16 - anchored to bottom so height below surface will vary
    • 08/13/07: put transducer in pipe

Pressure reported here is uncorrected for sea level. Add 85 millibar to correct for sea level.


  • CS106Vaisala PTB110 measures Barometric Pressure (
    • 06/09/16: Installed.


  • CS100Serta 278 measures Barometric Pressure (
    • 06/09/16: removed
  • CS105 Vaisala PTB101B measures Barometric Pressure (


  • SR50A measures snow depth ( The snow depth sensor cannot always detect early small quantities of snow that do not completely cover the vegetation. Therefore early snow events may not be recorded here. Check the webcam or calculate the albedo for information on the discontinuous snow season.

    Snow depth data can be noisy due to blowing snow or very low density snow.  In order to produce the 3 hour data, we took samples every 5 minutes.  We wrote a script that removed instances where there was more than a 1.0 cm of change in 5m, or if there was a grater than 0.5 cm change at the same time as a bad quality number from the instrument.  Once a data point was removed, the filter was stricter for immediately following measurements to be included.  We also manually corrected a handful of points. We then filled in the removed 5 minute points through linear interpolation and applied a 3 hour moving average.
    • 06/06/18: changed programing to hourly 'burst mode with median value'
    • 9/22/2017: replaced transducer
    • 8/26/2016: replaced transducer
    • 8/23/2015: replaced transducer
    • 5/16/2013: installed (possibly incorrectly programed at beginning so data table not storing)


  • CR3000 (, RF450 pair (, NL100 (
    • Note that raw logger files record midnight as 00:00:00 of the following day, while the websites database converts midnight to 24:00:00 of the current day.  If you are comparing data downloaded from the website to a raw data file, you may need to convert one of your data sets.
    • 06/06/2018: updated OS from std.6 to std.31.03, changed main scan rate from 60 to 30 secs, updated program


  • CR10x (, old radios

Datalogger: CR3000 Campbell Sci
14 differential (28 single-ended) analog input channels. 4 switched excitation outputs. 2 continuous analog outputs. 6 control ports. 4 pulse counting channels. 4 megabytes data storage memory. Extended range of -40°C to +85°C.

Multiplexer: AM25T, Campbell Sci.
The AM25T sequentially connects up to 25 thermocouples to a differential analog input on a CR800, CR850, CR10X, CR1000, CR3000, CR5000, CR7, or CR9000X datalogger. A PRT attached to the multiplexer's grounding bar provides a temperature reference for the thermocouple measurements. The heat capacity of the grounding bar and an insulated aluminum cover reduce thermal gradients along the length of the multiplexer. Reducing the thermal gradients allow more accurate measurements.

Pyranometer (Global Solar Radiation): Kipp & Zonen CMP-6
Spectral range 310 to 2800 nm. Sensitivity 5 to 20 μV/W/m2. Response time 18 s. Zero offset A ± 15 W/m2. Zero offset B ± 4 W/m2. Directional error (up to 80° with 1000 W/m2 beam) ± 20 W/m2. Temperature dependence of sensitivity (-10 °C to +40 °C) ± 4 %. Operating temperature range -40 °C to +80 °C. Maximum solar irradiance 4000 W/m2. Field of view 180°

Pyranometer/Pyrgeometer: Kipp & Zonen CNR-4
The CNR4 is a pyranometer and pyrgeometer pair that faces upward and a second pair that face downward. The pyranometers and pyrgeometers measure shortwave and long-wave infrared radiation, respectively. There is also an internal thermistor for temperature correction and a heater to prevent frost deposition. Spectral response: pyranometer 305 to 2800 nm, pyreometer 4.5 to 42 μm. Response time: < 18 s. Uncertainty in daily total: pyranometer < 5%, pyrgeometer < 10%. Operating temperature: -40° to 80° C.

Ultraviolet Pyranometer: Yankee Environmental Systems, Inc. UVA-1 and UVB-1
The UVB-1 and UVA-1 Pyranometers measure total irradiance from 280 to 320 nm and 320 to 400 nm, respectively. The instruments produce a high level 0-4 VDC output signal and are thermally stabilized for long term reference-grade measurements. Response time is approximately 100 ms.

Quantum Sensor (Photosynthetically Active Radiation): Li-Cor, Quantum. Model LI-190SB
Quantum measure photosynthetically active radiation (PAR) in μmol s-1 m-2. Specs: range 400-700nm wavelength. Sensitivity 8mA/1000 μmol s-1 m-2. Relative error less then ±10% for plant canopies or less then ±5% for growth chambers.

Underwater Quantum Sensor: Li-Cor Underwater Quantum. LI-192SB
Accurate measurement of PAR in Aquatic systems. Spec: Sensitivity 3mA/100mE s-1 m-2. Relative error less then ±5%. Temperature dependence ±0.15% per °C. Maximum pressure 800 psi.

Relative Humidity/Temperature: Vaisala HMP155A Temperature and Relative Humidity Probe
TEMPERATURE: Calibrated measuring range: -80 to +60°C. Accuracy at 20-60°C: ±(0.055 + 0.0057 × temperature)°C. Sensor type: Pt 100 RTD 1/3 class B IEC 751. RH: Measuring range: 0.8-100% RH. Accuracy at 15-25°C: ±1% (0 to 905), ±1.7% (90 to 100%). Response Time: 20 seconds (63% step change), 60 seconds (90% step change). Sensor type: HUMICAP®180R.

Wind Monitor: RM Young
Wind direction is determined by a potentiometer whose voltage is proportional to the direction of the vane. Range: 0° to 360° mechanical, 355° electrical (5° open). Starting Threshold: 1.1 m/s. Wind speed is determined by the frequency of a sine wave produced by a magnet on the propeller shaft. Range: 0-100 m/s, accuracy: ±0.3 m/s. There are currently two wind monitors at the same height for redundancy. Temperature range: -50°C to +50°C, assuming no rime.

Year-round Rain Gauge: Pluvio N Rain Gauge (OTT)
70.010.000B.E. (08.03.1995) Measures rainfall based on weighing principle.

Summer Rain Gauge: Texas Electronics, Inc. TE525(WS) (supplied by Campbell Scientific) Tipping Bucket Electric Rain Gauge
A complex spun collector funnel with a knife edge that diverts the water to a tipping bucket mechanism. For each tip a magnet causes an electronic pulse that is recorded. Each alternate tip occurs for each 0.01 inch of rainfall. Specs: Accuracy 1% at 2 inches/hr or less. Accurate Temperature Range: 0 - 37°C.

Snow Depth: Campbell Scientific SR50A Sonic Ranging Sensor
Snow depth is determined by sending an ultrasonic pulse to the surface and an electrostatic transducer that listens to the reflected echoes. Range: 0.5 - 10 meters, Accuracy: 0.4% of distance to target.

Thermocouples: Omega Engineering, Copper-Constantan wire
Range -200 to 350 °C. Limits of error: Standard wire 1.0°C or 0.75% above 0°C and 1.0°C or 1.5% below 0°C. Special wire 0.5°C or 0.4%.

Pressure Transducer: Druck , PDCR 930TI
5 psi: ± 0.5% F.S. Toolik lake depth.

Evaporation Pan: Novalynx 255-100
Evaporation gage measure water level in a standard U.S. Class A evaporation pan (size 25.4 cm H X 120.6 cm I.D.) and provides an output proportional to the level in the pan. Specs: 0-25 cm. Accuracy ±0.76mm.

Barometer: Campbell Scientific CS106 Barometric Pressure Sensor
Technical Description: Measures barometric pressure over 600 to 1060 mb range Accuracy is ±0.5 mb @ +20°C Manufactured by Vaisala, Inc.

Communication System (Radiotelemetry): Campbell Scientific
RF450 Radio transmitting to RF50 base station, and a direct Ethernet connection for redundancy.