Apogee MU-200 Owner's Manual - Page 9

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Apogee MU-200 Owner's Manual
Reset: To reset the meter, in either SMPL or LOG mode, push the mode button three times (RUN should be blinking), then
while pressing the down button, press the mode button once. This will erase all of the saved measurements in memory, but
only for the selected mode. That is, performing a reset when in SMPL mode will only erase the manual measurements and
performing a reset when in LOG mode will only erase the automatic measurements.
Review/Download Data: Each of the logged measurements in either SMPL or LOG mode can be reviewed on the LCD
display by pressing the up/down buttons. To exit and return to the real-time readings, press the sample button. Note that the
integrated daily total values are not accessible through the LCD and can only be viewed by downloading to a computer.
Downloading the stored measurements will require the AC-100 communication cable and software (sold separately). The
meter outputs data using the UART protocol and requires the AC-100 to convert from UART to USB, so standard USB cables
will not work. Set up instructions and software can be downloaded from the Apogee website
(http://www.apogeeinstruments.com/ac-100-communcation-cable/).
UV-B Measurements and Spectral Errors
Apogee Instruments MU series meters measure ultraviolet radiation between 250 and 400 nm in micromoles of photons per
square meter per second. Although the UV radiation between 280 and 315 nm (UV-B) is critically important in photochemical
and photobiological reactions, less than 3 % of the UV photons are in this range. Because only a small fraction of the photons
are in the UV-B range, the MU series meters cannot be used to selectively measure UV-B radiation. The MU series is sensitive
to UV-B radiation, but it is included with the UV-A radiation to provide a total measurement of UV radiation.
In addition to naturally occurring UV radiation from the sun, there are many electric light sources that emit UV radiation (e.g.,
cool white fluorescent, metal halide, mercury arc, and germicidal lamps). Although the relative wavelengths of UV radiation
differ among sunlight and electric lights, the error estimates shown in the table below indicate that the MU series meters
provide reasonable estimates of UV radiation coming from electric lamps (table provides spectral error estimates for UV
radiation measurements from radiation sources other than clear sky solar radiation). For common lamps, the error is less than
10 %. The MU series meters are particularly useful for determining the UV filtering capacity of the transparent plastic and
glass barriers that are commonly used below electric lamps.
Spectral Errors for UV Radiation Measurements with Apogee MU series UV meters
Radiation Source (Error Calculated Relative to Sun, Clear Sky)
Sun (Clear Sky)
Sun (Cloudy Sky)
Reflected from Grass Canopy
Reflected from Deciduous Canopy
Reflected from Conifer Canopy
Reflected from Agricultural Soil
Reflected from Forest Soil
Reflected from Desert Soil
Reflected from Water
Reflected from Ice
Reflected from Snow
Cool White Fluorescent (T5)
Metal Halide
High Pressure Sodium
Incandescent
Mercury Arc
Error [%]
0.0
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
< 0.5
9.0
2.8
-1.7
-3.3
17.8
9