Globe Anemo-radiometer

Abstract

We report on a new sensing technology for wind speed \((U)\) and shortwave and longwave radiation fluxes (\(S\) and \(L\), respectively) known as a “globe anemo-radiometer” (GAR). The GAR is intended for portable use in mobile observations along individual human pathways. The device was carefully designed to be compact, light, and omnidirectional, with low power consumption. The GAR evaluates the heat transfer coefficient \((h),\,S\), and \(L\) by solving the simultaneous heat balance equations of three globe thermometers with different surface properties. The optimal combination of the three globe thermometers, namely a black globe thermometer, a white globe thermometer, and a black globe thermometer with a heat source inside the sphere, was determined experimentally. \(U\) was evaluated using the empirical regression of \(h\) against \(U\), with the relationship between the Nusselt number and Reynolds number experimentally regressed for the conversion from \(h\) to \(U\), and the result compared with previous values from the literature. The performance of the GAR as a stationary sensor was evaluated in both field and wind-tunnel experiments and compared with that of reference meteorological sensors. The accuracy of determining \(U\) obtained by the GAR was \(0.24\,\hbox {m s}^{-1}\) averaged over a 1-min time frame, and that of \(S\) and \(L\), applying a 5-min moving average, 19 and 15 W m\(^{-2}\) respectively. Both the accuracy and response delay of the globe thermometers were possible sources of error.