Apogee MQ-501 Руководство пользователя - Страница 14

Просмотреть онлайн или скачать pdf Руководство пользователя для Измерительные приборы Apogee MQ-501. Apogee MQ-501 19 страниц. Quantum meter

MAINTENANCE AND RECALIBRATION

Moisture or debris on the diffuser is a common cause of low readings. The sensor has a domed diffuser and

housing for improved self-cleaning from rainfall, but materials can accumulate on the diffuser (e.g., dust during

periods of low rainfall, salt deposits from evaporation of sea spray or sprinkler irrigation water) and partially block

the optical path. Dust or organic deposits are best removed using water, or window cleaner and a soft cloth or

cotton swab. Salt deposits should be dissolved with vinegar and removed with a soft cloth or cotton swab. Never

use an abrasive material or cleaner on the diffuser.

The Clear Sky Calculator (www.clearskycalculator.com) can be used to determine the need for quantum meter

recalibration. It determines PPFD incident on a horizontal surface at any time of day at any location in the world. It

is most accurate when used near solar noon in spring and summer months, where accuracy over multiple clear and

unpolluted days is estimated to be ± 4 % in all climates and locations around the world. For best accuracy, the sky

must be completely clear, as reflected radiation from clouds causes incoming radiation to increase above the value

predicted by the clear sky calculator. Measured values of PPFD can exceed values predicted by the Clear Sky

Calculator due to reflection from the sides and edges of clouds. This reflection increases the incoming radiation.

The influence of high clouds typically shows up as spikes above clear sky values, not a constant offset greater than

clear sky values.

To determine recalibration need, input site conditions into the calculator and compare PPFD measurements to

calculated PPFD values for a clear sky. If sensor PPFD measurements over multiple days near solar noon are

consistently different than calculated values (by more than 6 %), the sensor should be cleaned and re-leveled. If

PPFD measurements are still different after a second test, email

to discuss

test results and possible return of meter(s) for recalibration.