NWTC M2 Instrument Descriptions and Histories


Model Measurement
Notes (below)
Units Install
Date
Removal
Date
Current
SN
Current
CF
PSP Global Horizontal (Ventilated)
& Accumulated Irradiation
W/m2
kWhr/m2
09/23/1996 - 20517F3 110.94 W/m2/mV
Total Hemispheric shortwave irradiance as measured by an Eppley Laboratory, Inc. Model PSP (Precision Spectral Pyranometer) with calibration factor traceable to the World Radiometric Reference (WRR). The instrument is calibrated annually by NREL at the Solar Radiation Research Laboratory (SRRL). The Accumulated Global Horizontal is also calculated in the datalogger and reset every midnight (standard time). The ventilated PSP is mounted several feet above ground level.
SS-201 Wind Speed m/s 09/23/1996 - N3305
N3310
N3308
N3312
N3319
N3309
0.0434 m/s/Hz+0.3390 m/s
0.0438 m/s/Hz+0.3284 m/s
0.0430 m/s/Hz+0.2946 m/s
0.0434 m/s/Hz+0.3012 m/s
0.0431 m/s/Hz+0.2867 m/s
0.0440 m/s/Hz+0.2927 m/s
The mean wind speed at 80, 50, 20, 10, 5, and 2 meters. The peak wind speed and the standard deviation (during the one minute interval) are also recorded. The Wind Speed sensors are calibrated annually in a Met One Wind Tunnel. Prior to December 30, 2009 at 12:35 MST, the wind speed sensors were measured using a Campbell Scientific SDM-INT8 interval timer, which samples the sensors at a high frequency (up to 1 microsecond) and reports the average value to the data logger.
SD-201 Wind Direction o from N 09/23/1996 - N3403
N3430
R3403
N3405
R3408
P3419
0.0792 o/mV
The mean wind direction vector at 80, 50, 20, 10, 5, and 2 meters. The wind direction (at the peak wind speed) and the standard deviation (during the one minute interval) are also recorded. Annually a Functional Check Only (FCO) is performed on the wind direction sensors by Met One.
T-200 Temperature oC 09/23/1996 - 0890359
0912630
239975
C0=-254.148; C1=26061.0; C2=-14.5313; C3=0.081164; M = 0.0001
C0=-245.845; C1=23697.4; C2= 8.09644; C3=0.008906; M = 0.0001
C0=-253.720; C1=26021.9; C2=-14.4319; C3=0.080737; M = 0.0001
The PRT temperature sensors are at 80, 50, and 2 meters and are mounted in an aspirator. The PRT sensors are calibrated annually at the NREL Metrology Lab and the coefficients were derived from the temperature vs. resistance calibration data. The temperature which is a function of resistance, is calculated using the following third order polynomial: Temp(R) = C0 + M*(C1*R + C2*R2 + C3*R3), where R = Resistance (Ohms).
BP200B Dew Point Temperature oC 09/23/1996 - 23352-001 Inst. P16
The dew point sensor is at 2 meters. This is a new sensor that is using the factory calibration, therefore uses Campbell Inst P16 to calculate the cell temperature from resistance. The dew point is then calculated using this formula: Tempdp=0.68434*Tempcell-23.88; if Tempdp<0, then Tempdp*=1.1.
(calc) Relative Humidity % 09/23/1996 - n/a n/a
The relative humidity is calculated in the datalogger using dew point and temperature at 2 meters.
(calc) Specific Humidity g/Kg 08/24/2001 - n/a n/a
The specific humidity is calculated in the datalogger using dew point and station pressure.
(calc) Wind Chill oC 08/24/2001 - n/a n/a
The wind chill is calculated in the datalogger using temperature and wind speed at 2 meters. As of Dec. 13, 2002 the formula is based on the new National Weather Service method described on the NOAA web site. Note: Prior to this date wind speed at 10 meters was used.
(calc) Average Wind Shear oC 08/24/2001 - n/a n/a
The wind shear is calculated in the datalogger by taking the difference in wind speed at two adjacent levels and dividing by their distance (in meters) from each other. This is done for each pair of adjacent levels and then all five are averaged.
AIR AB-2AX Station Pressure mBar 09/23/1996 - 4E0029 0.052 mBar/mV+740mBar
The Pressure Transmitter is physically mounted inside M2 shed, however the measurements are made outside at an elevation of 1857.5 meters. The pressure sensor is calibrated every two years at the NREL Metrology Lab
(calc) Est. Sea-Level Pressure mBar 08/24/2001 - n/a n/a
The approximate sea-level pressure is calculated using station pressure and site elevation.
302-B Precipitation Gauge (tipping bucket) mm 09/23/1996 - - 0.254 mm/count
The accumulated precipitation is outputted by the datalogger and reset every midnight (standard time). The Belfort heated precipitation gauge is mounted a few feet above ground level near the tower.
4212/12 Aspirator Fan Speed RPM 08/24/2001 - - 30 RPM/Hz
Aspirator Fans are spec'd at 3050 RPM (open air) and run at approx. 2900 RPM when installed in the 2m aspirator (higher level aspirators will be lower). Prior to January 25, 2002 at 12:00 MST, the aspirator status was reported by a microswitch connected to a baffle, if the value is zero then the aspirator may be malfunctioning.
- CR23X Battery Voltage V 08/24/2001 - - -
CR23X internal battery voltage. The CR23X data logger is located inside the M2 shed.
- CR23X Panel Temperature V 08/24/2001 - - -
CR23X internal temperature sensor is located under wiring panel. The CR23X data logger is located inside the M2 shed.
(calc) Turbulence Intensity - 09/23/1996 - n/a n/a
Calculated for all levels (2, 5, 10, 20, 50 and 80 meters) after datacollection (outside the datalogger) and added to the datastream. Turbulence Intensity is the wind speed standard deviation divided by the average wind speed.
(calc) Richardson Number - 09/23/1996 - n/a n/a
Calculated for 2-50m, 2-80m, and 50-80m after datacollection (outside the datalogger) and added to the datastream. See NREL technical report at bottom of page.
(calc) Friction Velocity (u*) m/s 09/23/1996 - n/a n/a
Calculated after datacollection (outside the datalogger) and added to the datastream. See NREL technical report at bottom of page.
(calc) Est. Surface Roughness m 09/23/1996 - n/a n/a
Calculated after datacollection (outside the datalogger) and added to the datastream. See NREL technical report at bottom of page.
(calc) u* Quality Control (r2) - 09/23/1996 - n/a n/a
Calculated after datacollection (outside the datalogger) and added to the datastream. See NREL technical report at bottom of page.
(calc) Power Law Coef. (2-80m) - 09/23/1996 - n/a n/a
Calculated after datacollection (outside the datalogger) and added to the datastream. See NREL technical report at bottom of page.
EFM-100 Atmospheric Electric Field kV/m 07/22/2010 - unknown n/a
Measured by a Boltek EFM-100 Atmospheric Electric Field Monitor mounted a few hundred yards east of the M2 tower. Data is collected by an independent system and added to the datastream.
Notes:

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