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PRES

Station Pressure

The average station pressure during the last 5-minute interval.

  • A short length of tubing extends from the pressure port to outside of the datalogger enclosure in order to expose the barometer to the free atmosphere.
  • Barometric pressure is not corrected for the elevation of the station above sea level. However, changes in pressure over time at any given station are very accurate measurements.
Type Sensor Used Standards Units Accuracy
Standard - Primary Vaisala Barometer, PDF millibars (mb) ±0.4 mb for air temperatures between -30 and 50 °C

Vaisala Barometer Sensor

PALT

Pressure, Reduced to Sea Level

Not measured, but computed from the barometric station pressure and the station elevation.

  • Pressure, Reduced to Sea Level, should be used to compare pressures between two stations at different elevations. Sea level pressure is an approximation of the station's barometric pressure under a standard atmosphere if the station were located at sea level.
Sensor Used Standard Units Accuracy
Vaisala Barometer, PDF millibars (mb) ±0.4 mb for air temperatures between -30 and 50 °C

Vaisala Barometer Sensor

SRAD

Solar Radiation

The average amount of downwelling global solar radiation received at the station during the last 5-minutes.

  • The measurement of solar radiation does not include radiation emitted from the earth or atmosphere. However, the pyranometer will detect solar radiation which is reflected downward in the atmosphere (e.g., by molecules, clouds, etc.). Note that the sensor points upward and thus does not measure solar radiation reflected upward from the ground.
  • Calibration coefficients are applied to the data in real-time during processing.
  • Solar radiation measurements in the morning and evening are sensitive to obstruction (e.g., trees) on the east and west horizons. A delay of sunrise or early arrival of sunset at a particular station may be explained by examining panoramic site photos available at http://www.mesonet.org/index.php/site/sites/mesonet_sites.
Type Sensor Used Standards Units Accuracy
Standard - Primary Li - Cor Pyranometer, PDF Watts per square meter (Wm-2) ±5%

Li - Cor Pyranometer Sensor