In situ calibration of four-wire hot-wire probes for atmospheric measurement

An in situ calibration methodology to use hot-wire anemometry for the measurement of atmospheric flow without the need for prior calibration is presented. The application of this method is expected to facilitate the usage of hot-wire anemometry to study atmospheric turbulence structures with a higher temporal and spatial resolution compared to conventional methods, such as sonic anemometry. In this method, the hot-wire anemometer is calibrated after the field experiment using the velocity data acquired from a sonic anemometer operating simultaneously. In this paper, a proper data reduction methodology is developed to perform the in situ calibration and extract the desired velocity information. The feasibility of this in situ operation of hot-wire anemometry is tested in an atmospheric research facility in the coastal region of Doha, Qatar. The obtained turbulence data is then compared with the data obtained from the sonic anemometer. Results show a good agreement between the data from the hot-wire probe, obtained at higher sampling rate, with that of the sonic anemometer measurement. In addition, application of the hot-wire probe provides the added advantage of the higher spatial and temporal measurement resolution. Finally, sensitivity of the proposed method to random noise in the input voltage is then numerically analyzed using a Monte Carlo simulation.

► Introducing a novel in situ calibration method for four-wire hot-wire probes.
► Proposing simple calibration and operating procedures for four-wire probes in atmospheric flow.
► The new method provides higher spatial calibration without an increased in calibration effort.
► This method eliminates the need for frequent calibration due to drift in calibration constants.
► The applicability of the procedure is verified through field experiment.