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| TEMPERATURE The most usual temperature measurement is that of ambient air temperature. The measurement is easily disturbed particularly by solar radiation. For this reason the measurement is typically done in a shielded but at the same time ventilated surrounding, created by a so-called "radiation screen" see EnviroTech Sensors and R.M. Young. The temperature measurements is typically combined with a humidity measurement. Special housings with louvered screens are manufactured by Metspec. Well known combined humidity/temperature measurements are manufactured by Vaisala and Rotronic. For some high frequency temperature measurements (turbulence) one would need active ventilation and a differential temperature measurement. Typical system configuration can be found at Campbell Scientific Bowen Ratio systems. Sonic anemometers will also give temperature information, however this must be corrected for pressure and humidity. For temperature stability measurements in surface energy balance: see also the scintillometers of Kipp & Zonen and Scintec. Scintillometers measure vertical temperature gradients across a large area. For temperature profiles across the boundary layer also microwave profilers, tethered balloons can be considered. |
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