A data logger, in the LTER moist acidic experimental plots (in block 2), is used to monitor weather and soil temperatures.
Sensors in the control plot include: global solar radiation, photosynthetic active radiation, unfrozen precipitation, air temperature, relative humidity, wind speed, and wind direction at 3 meters. Additional seasons in greenhouses and shade houses plots measure air temperature, relative humidity and photosynthetic active radiation during the growing season. These sensors are read every minute and averaged or totaled every hour.
Two profiles of soil temperature are measured per treatment plot with copper/constantin thermocouple wires (TC) installed at depths of 10, 20, and 40 cm in inter-tussock areas. The following label codes are used: CT = control, GH = greenhouses, SH = shade houses, F = fertilized, GF= greenhouse fertilized, SF = shade house fertilized, plus a 1 or a 2 for the profile number. All soil sensors are read every 15 minutes and averaged every 3 hours.
Hourly, three hourly and daily summaries are in files yyyyDLMATH.DAT, yyyyDLMATO.DAT, and yyyyDLMATD.DAT respectively, where yy is the year in which the data are collected. The original data are in file yyDLMATDAT.ZIP which is archived at The Marine Biological Lab, Woods Hole, MA.

NOTES:

The covers on greenhouses and shade houses are removed every fall and reinstalled every spring. Seee comment variable for dates.

Soil temperatures are problematic since frost heaving of the probes caused depth of measurements to change. Probes were measured on 15Aug2006 and then reset to the correct depth if possible, see below. Data that were 3 cm or more off the expected depths were deleted. See Frost heaving was assummed to occurred in early June.

On Aug 15 error in depth was measured and we are assuming any error due to frost heave occurred in June.
CT1 10, Error before (cm), 5, Error after (cm), 0
CT2 10, Error before (cm), 1, Error after (cm), 0
GH1 10, Error before (cm), 5, Error after (cm), 0
GH1 20, Error before (cm), 5, Error after (cm), 0
GH1 40, Error before (cm), 5, Error after (cm), 0
NP1 10, Error before (cm), 5, Error after (cm), 5
NP1 20, Error before (cm), 5, Error after (cm), 5
NP1 40, Error before (cm), 5, Error after (cm), 5
GHNP2 10, Error before (cm), 5, Error after (cm), 0
SHNP1 10, Error before (cm), 3, Error after (cm), 3
SHNP1 20, Error before (cm), 3, Error after (cm), 3
SHNP1 40, Error before (cm), 3, Error after (cm), 3
SHNP2 20, Error before (cm), 5, Error after (cm), 0

Missing values are indicated by #N/A. Where values were deleted due to errors in depth due to frost heaving a blank is entered.

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Sensor Description

Following are brief descriptions of the sensors used at the weather monitoring station. Included with each description is a list of stations using the sensor and the number of sensors at that site. Company addresses follow the list.
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PYRANOMETER:
Li-Cor, Pyranometer: Model LI-200SA- Sensor measures global solar radiation (sun plus sky). Specs: Sensitivity - 80mA per 1000 Watts m-2. Absolute error max ±5% but typically ±3
QUANTUM:
Li-Cor, Quantum. Model LI-190SB. Quantum measure photosynthetically active radiation (PAR) in mol s-1 m-2. Specs: range 400-700nm wavelength. Sensitivity 8mA/1000 mol s-1 m-2. Relative error less then ±10% for plant canopies or less then ±5% for growth chambers. Toolik.
RELATIVE HUMIDITY/TEMPERATURE:
Campbell Scientific, CS500 Temperature and Relative Humidity Probe. Uses PRT for temperature measurement; capacitive RH chip for RH. Accuracy is ±3% over 10-90% RH; ±6% over 90-100% RH. Manufactured by Vaisala, Inc.
WIND DIRECTION:
MET-ONE, (supplied by Campbell Scientific) Wind direction use a light weight, air foil vane and a potentiometer to produce an output that varies proportional with wind direction. Specs: Minimum Wind speed to get accurate reading = 1.0 mph. Accuracy ±5° Temperature range -50 to 70°C.
WIND SPEED:
MET-ONE, (supplied by Campbell Scientific) Wind speed sensor Model 014A. Sensor uses a 3-cup anemometer assembly and simple magnet-read switch assembly to produce a series of contact closures whose frequency is proportional to wind speed. Specs: Operating Range - 0 to 125 mph or 0-60 m/s. Accuracy ±1.5% or 0.25 mph. Working temperature range - -50 to 85°C
RAIN GAUGE:
Texas Electronics, Inc. (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. Alter wind shield installed around gauge.
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%.
List of manufactories and suppliers.
Campbell Scientific, Inc.
81 W. 1800 N.
Logan, Utah 84321-1784
(435)750-1739

Druck Inc.
4 Dunham Drive
New Fairfield, CT 06812
(203)746-0400

Li-Cor
4421 Superior St
P.O. Box 4425
Lincoln, Nebraska 68504
(800)447-3576

Omega Engineering, Inc.
P.O. Box 4047
Stamford, CT 06907-0047
(800)826-6342

Reference Citations: Buck, A.L. 1981 New equations for computing vapor pressure and enhancement factor. Journal of Applied Meteorology 20:1527-1532.