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Net Radiation Measurements
Published in Frank Vignola, Joseph Michalsky, Thomas Stoffel, Solar and Infrared Radiation Measurements, 2019
Frank Vignola, Joseph Michalsky, Thomas Stoffel
The simplicity of concept and construction of a single-unit-construction net radiometer would appear to be a good design. The hot junction of the thermopile is connected to the top of the detector, which receives downwelling shortwave and longwave radiation, and the cold junction is connected to the bottom of the detector, which receives upwelling shortwave and longwave radiation. The difference in temperature of these matched receivers is proportional to the net radiation. To reduce the effects of wind, dust, and precipitation on the detector, a material that transmits both solar and IR radiation protects the surfaces, usually polyethylene. Since thermopile responses are sensitive to temperature, it is best to include a measurement of the thermopile temperature needed to make this correction. A bubble level is used to ensure the proper horizontal orientation of the instrument, and a desiccant holder located within the housing is often included to eliminate internal condensation. The cost of this sensor tends to be much lower than the multi-sensor net radiometers. Examples of commercially available instruments of this type of net radiometer are the Radiation and Energy Balance Systems (REBS) Q-7.1 and the Kipp & Zonen net radiometer (NR) Lite2. Figure 12.2 is an example of a single-sensor (all-wave) net radiometer.
Surface water and the atmosphere
Published in Ian Acworth, Investigating Groundwater, 2019
A net radiometer consists of two pairs of radiation sensors. Incoming short- and long-wave radiation is measured by one pair of sensors, while outgoing long- and short-wave radiation are measured by a second pair of sensors. A radiometer installation from Kipp and Zonen is shown in Figure 2.22. The net radiation corrected for temperature is output to the climate station.
Experimental and Theoretical analysis of the urban overheating and its mitigation potential in a hot arid city – Alice Springs
Published in Architectural Science Review, 2020
Shamila Haddad, Giulia Ulpiani, Riccardo Paolini, Afroditi Synnefa, Mattheos Santamouris
The short-term ground-based survey was designed to map the meteorological conditions, namely air temperature, relative humidity, wind speed and direction, solar radiation and thermal radiation fluxes at 35 locations (Figure 2). Measurements at each point were conducted for 10 min, collecting information with a net radiometer and a weather station (Table 1). The net radiometer (NR01 by Hukseflux) measured the downward and upward solar radiation and the incoming and outgoing longwave radiation, with the balance of the four components giving the net radiation. The albedo was computed as the ratio of the measured reflected to incoming shortwave radiation, with the instrument at 0.5 m to maximize the view factor to the ground and minimize the interference from objects and shadows, while the sky and surface temperatures were computed out of the longwave radiation readings. A weather station (MetPak Pro by Gills Instruments) monitored the air pressure, air temperature and dew point temperature (out of which the humidity is computed), wind speed and direction at 1.1 m, which is representative of a standing person (Mayer and Höppe 1987).