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Downward looking LI-COR 210SZ radiation sensor
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- Use in the USDA UVB Monitoring Network
The model 210SZ
LI-COR
photometer is used in the USDA's UVB monitoring
program as a simple indicator of surface reflectance. The photometer is
pointed downward, instead of skyward and therefore responds to illumination
reflected from the seasonal ground cover just below and around the
network's instrument array. The importance of this measurement is in
determining the presence of snow cover.
Because of the photometer's use within the network and its unconventional
orientation, the network has chosen to apply a single, constant calibration
conversion (30.69 mA/ 100K lux) to all of its meters rather than specific
constants for each meter as furnished by the manufacturer. Since the stated
calibration constants for the network's LI-COR photometers range from
27.86 - 33.51mA per 100K lux, this introduces an additional uncertainty in
the reported measurements of approximately 7%. This uncertainty, however,
is more than acceptable for the instrument's intended use. To further
differentiate the network's photometric results from other LI-COR
photometer results, the network reports the meter's output in units of
Watts/Meter-squared rather than lux as is suggested by the
manufacturer. This unit conversion has been made using the 1 Watt = 683
lumens as recommended by the manufacturer.
The simple use to which the photometer is applied does not warrant any
specific quality assurance procedures other than checks to ensure that
the photometer is operating. The network does not intend to maintain
current photometer calibrations.
- Manufacturer's Information
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