Uncertainty of Pure Rotational Raman-Rayleigh LiDAR for Temperature Measurement in Middle-to-Upper Atmosphere: Simulation Method

This article initiates a series focusing on the uncertainties associated with temperature measurements using pure rotational Raman-Rayleigh LiDAR in the mid-to-upper atmosphere (20-90 km). We introduce a comprehensive simulation system designed for temperature measurement using pure rotational Raman-Rayleigh LiDARs. This simulation system considers hardware parameter fluctuations, atmospheric parameter variations, and detailed retrieval algorithms during the temperature detection process. Using the Monte Carlo method (MCM), the system achieves, for the first time, a simulation of temperature measurement uncertainties throughout the entire LiDAR measurement process. This article provides an illustrative example of applying the uncertainty simulation system to a prototype. In this example, photon noise (PN), the reference temperature (RT), the laser wavelength (LW), and saturation correction (SC) are significant sources of uncertainty in Raman LiDAR, whereas in Rayleigh LiDAR, PN, SC, and the RT play major roles. Additionally, sensitivity experiments of the uncertainty components are carried out to analyze the linearity of the uncertainty propagation in the two LiDAR systems. Then, two special cases of uncertainty coupling are discussed, which reveals the complexity of uncertainty propagation in LiDARs. The simulation method proposed in this article aids in identifying key sources of measurement uncertainty during the entire measurement process, offering insights for hardware selection and system design in LiDAR development.