Definitions and units for 2008 North Pole data
Radiation data in 22204_hdr.rad
PIR The PIR is an Eppley radiometer that measures incoming radiation with wavelengths between 3.5 and 50 µm. This instrument is also called a pyrgeometer. Units are Watts/m**2
Case and dome temperatures – these are the temperatures of the PIR case ( the metal housing) and of the silicon dome that allows radiation into the instrument. The case temperature is needed to transform the PIR measurement (in mV) to W/m**2. Some researches also use the difference between the dome temperature and case temperature to refine the measurement. We haven’t done this – it requires additional calibration - but do include both temperatures to assess when that factor might be important.
PSP The PSP is an Eppley radiometer that measures solar radiation from 0.285 to 2.8µm. This type of instrument is also called a pyranometer. Case temperature is not needed in this instrument’s calculations. Units are Watts/m**2.
Tilt X and Tilt Y are the number of degrees the platform holding the radiometers is tilted from horizontal. The radiometers were leveled when they were deployed, but ice melt may cause the entire station –including the radiometers - to tilt.
Battery voltages – This buoy uses lithium batteries to power the buoy itself, and rechargeable batteries that run heaters and fans that try to keep the instrument domes from frosting over.
Weather Station data in 07100_hdr.wx
AirT 1 and AirT 2 The weather station measures two air temperature values. AirT 2 was in the usual thermistor shield. Some researchers have suggested that the thermistor shield heats up and affects the reading, so another reading (AirT 1) was made in air pulled past the thermistor by a fan. Both are degrees C.
AirPr is air pressure, in millibars
Wu Wv Ws and Wdir are the vector wind components (u to the east, v to the north) and wind speed and direction (to). Wind units are m/s.
Tilt: The weather station contains a compass that reports pitch and roll (the two tilt values reported at the far right) as well as the orientation of the weather station (the heading). The wind direction reported by the station is the orientation of the wind sensor to this heading, so its value is necessary to correct the wind direction to degrees magnetic.
Declination is the declination of the earth’s magnetic field. Declination, needed to calculate true wind directions from magnetic direction, is extremely variable in the Arctic. We downloaded a table of values of the declination every 0.5 degree of latitude and longitude from http://www.ngdc.noaa.gov/geomagmodels/IGRFGrid.jsp and use the value closest to the location of the buoy at every calculation.