Pyranometer offsets triggered by ambient meteorology: insights from laboratory and field experiments
This study investigates the effects of ambient meteorology on the accuracy of radiation (<i>R</i>) measurements performed with pyranometers contained in various heating and ventilation systems (HV-systems). It focuses particularly on instrument offsets observed following precipitation ev...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-03-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | http://www.atmos-meas-tech.net/10/1169/2017/amt-10-1169-2017.pdf |
| Summary: | This study investigates the effects of ambient meteorology on the accuracy of
radiation (<i>R</i>) measurements performed with pyranometers contained in various
heating and ventilation systems (HV-systems). It focuses particularly on
instrument offsets observed following precipitation events. To quantify
pyranometer responses to precipitation, a series of controlled laboratory
experiments as well as two targeted field campaigns were performed in 2016.
The results indicate that precipitation (as simulated by spray tests or
observed under ambient conditions) significantly affects the thermal
environment of the instruments and thus their stability. Statistical analyses
of laboratory experiments showed that precipitation triggers zero offsets of
−4 W m<sup>−2</sup> or more, independent of the HV-system. Similar offsets
were observed in field experiments under ambient environmental
conditions, indicating a clear exceedance of BSRN (Baseline Surface Radiation Network) targets following
precipitation events. All pyranometers required substantial time to return to
their initial signal states after the simulated precipitation events.
Therefore, for BSRN-class measurements, the recommendation would be to flag the
radiation measurements during a natural precipitation event and 90 min after it in nighttime conditions. Further daytime experiments
show pyranometer offsets of 50 W m<sup>−2</sup> or more in comparison to
the reference system. As they show a substantially faster recovery, the
recommendation would be to flag the radiation measurements within a natural
precipitation event and 10 min after it in daytime conditions. |
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| ISSN: | 1867-1381 1867-8548 |