The Finnish Meteorological Institute (FMI) has an Atmospheric Research Centre in Kuopio, a city located in the lakes region of Eastern Finland. Situated on the building’s roof is a solar radiation measurement site and, at ground level, an automated weather station known as Kuopio Savilahti.
Image Credit: OTT HydroMet
In a recent case study, Kipp & Zonen radiometers were used to evaluate the effects of various types of ventilation units on keeping pyranometers clean, specifically in the harshest winter conditions such as snow, freezing rain, frost and other severe weather conditions.
Each of the three CMP11 pyranometers was fitted with a different ventilation unit, Kipp & Zonen CVF3 and CVF4 models and a customized design, all of which were heated on a continuous basis. A fourth CMP11 was not ventilated and was used as the control case for comparison.
It was observed that each of the ventilation units worked well when it came to maintaining the cleanliness of the domes and preventing the major effects of bad weather conditions on the radiation measurements.
During the month of February, frozen sleet hit all ventilation units, which were then able to successfully evaporate the sleet that accumulated on the domes.
In this instance, the unventilated CMP11 displayed a high reading, up to 38%, before cleaning (see photo). Pyranometer 4 represents the unventilated CMP11 in the example graph.
Image Credit: OTT HydroMet
Additionally CMP11 + CVF4 (Pyranometer 1), CMP11 + CVF3 (Pyranometer 2) and CMP11 + custom ventilator (Pyranometer 3) are displayed. The pyrgeometer is an unventilated CGR3, and the impact of ice on the window is displayed.
This initial review of the case study results proves that it is necessary to use a ventilation unit and heating system when using pyranometers exposed to the Finnish winter.
Image Credit: OTT HydroMet
This information has been sourced, reviewed and adapted from materials provided by OTT HydroMet.
For more information on this source, please visit OTT HydroMet.