Hourly weather data from the Arctic Tundra LTER wet sedge experimental site at Toolik Lake. The following parameters are measured every minute and averaged every hour: control and greenhouse plot air temperature and relative humidity at 3 meters.
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Starting in June 1994 weather data has been collected in the wet sedge experimental plots (block 1) at the Arctic Tundra LTER site at Toolik Lake. Air temperature and relative humidity (3 meters) and soil temperatures at surface, 10 and 25 cm depths are measured on the following treatment plots:
- Nitrogen alone
- Phosphorus alone
- Nitrogen plus phosphorus
Air temperature and relative humidity are measured every minute and averaged every hour while soil temperatures are measured every 3 minutes and averaged every 4 hours. The shade and greenhouses covers are only installed June thru August.
Sensor and Equipment Description
Following are brief descriptions of the sensors used. Company addresses follow the list.
- Data Logger - Campbell Scientific CR10 Multiplexer - Campbell Scientific AM416 Panel temperature - Campbell Scientific 10TCRT Air temperature/ RH - Campbell Scientific 207; Humidity sensor replaced every 2-3 years. Replaced with CS500 Aug 1999
- Soil Thermocouples - Custom made using 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%.
- Campbell Scientific, Inc.
81 W. 1800 N.
Logan, Utah 84321-1784
Omega Engineering, Inc. P.O. Box 4047 Stamford, CT 06907-0047 (800)826-6342
- DAYS: JULIAN + (HOUR/2400)
- VAPOR PRESS: If Air Temp > 0 then (RH /100) * 6.1121 * exp(17.368 * AIR TEMP /(238.88 + AIR TEMP )) If Air Temp < 0 then (RH /100) * 6.1121 * exp(17.966 * AIR TEMP/(238.88 + AIR TEMP )) From Buck 1981. Reference Citations: Buck, A.L. 1981 New equations for computing vapor pressure and enhancement factor. Journal of Applied Meteorology 20:1527-1532
Notes and comments
- Shade and greenhouses are not covered year round. They are covered early June and uncovered mid-August. The sensors are up year round.
- During the winter of 1994-1995 a program error caused the data from 20Aug94 to 28Mar95 to be lost. Data was also lost during winter 1995-1996.
- 1996 – Relative humidity is low, never reaching above 90%. Data were not corrected. RH sensor replace summer 1996.
- 1999 18Aug Changed out the 207 temp/RH sensor replacing with a CS500. Since the CS500 only goes to -39 C the 207 is used to measure the temperatures below -40C and as a backup. Note that the 207 measurement error below -40 C is large. See Campbell's manual on the 207/107. The 207 was discontinued since the RH senor is no longer available.
- 2001 Added a subroutine to calculate the reference and air 107 temperature probes using a Steinhart-Hart equation: The voltage of a 107 probe is converted to resistance then converted to both Kelvin and Celsius using 1/T= A + B ln Rs + C(lnRs)^3 where T = Kelvin and A,B and C are constants derived from the temperature vs resistance data of the Fenwell thermistors. Rs is the measured resistance. This will improve the accuracy of temperatures below -30C.
- 2002 The control relative humidity sensor stopped working. Not sure why.
- 2003 The data logger stopped collecting data from Feb through May. The temperature and RH sensors failed from May to August due to a faulty splice in the cable. The 3 meter temperature was not replaced until June 2004
- 2004 The 3 meter temperature/RH probe replace June with the same model - CS500
- 2011 Lost power from 4Aug to 6Aug caused by a corroded battery wire.
- 2012 Replace 207 with a 107 Thermistor. The old 207 cable was cracking. The 107 is in the same shield as the CS500.
Version 3 Added the hourly metadata data to one file. With data tables for years 1994-1999 and 2000- present. Check and estimated date where possible. See notes in methods and the Comment variable. Jim L Nov 2015
Download a comma delimited (csv) or Excel file (includes metadata and data sheets).
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