Evaluation of two common source estimation measurement strategies using large-eddy simulation of plume dispersion under neutral atmospheric conditions

Abstract. This study uses large-eddy simulations (LESs) to evaluate two widely used observational techniques that estimate point source emissions. We the use of car measurements perpendicular wind direction and commonly Other Test Method 33A (OTM 33A). The LES simulates a plume from released into stationary, homogeneous, neutral atmospheric surface layer over flat terrain. choice is motivated by our ambition validate methods under controlled conditions where they are expected perform well since sources uncertainties minimized. Three plumes with different release heights were sampled in manner mimics sampling according transects stationary OTM 33A. Subsequently, strength estimates compared true simulation. Standard deviations estimated strengths decay proportionally inverse square root number averaged transects, showing statistical independence individual samples. analysis shows for transect at least 15 repeated measurement series need be obtain within 40 % strength. For analysis, which recommends 200 m source, have similar values close caused insufficient dispersion turbulent mixing source. Additionally, derived substantially overestimated overestimation driven proposed coefficients, too large this specific case. suggests constants likely influenced motions length scales beyond scale layer. Lastly, indicate that, due wind-shear effects, position time-averaged centerline may differ emission height. mismatch can an additional error if Gaussian model (GPM) interpret measurement. In case measurements, correct then requires adjustment height GPM.