A Saturation Correction Method for Temperature Measurement of Pure Rotational Raman Lidar

Abstract

The invention relates to a saturation correction method for temperature measurement of a pure rotational Raman lidar and belongs to the technical field of measurement. The method comprises the first step of obtaining original high-order echo signals and original low-order echo signals of the pure rotational Raman lidar and obtaining high-order channel echo signals with the background removed and low-order channel echo signals with the background removed, and the second step of judging whether the phenomenon of saturation of the near-ground photon number exists, and if yes, achieving saturation correction of the near-ground photon number by selecting electronic identification level values mu of different multiplier systems. In this way, causes of the near-ground saturation phenomenon can be analyzed according to underlying causes of photon counting nonlinearity, namely the pulse height distribution and the electronic identification level; the temperature retrieval process is conducted through the corrected high-order channel echo signals and the corrected low-order channel echo signals, and the accuracy of the pure rotational Raman lidar in measuring the atmosphere temperature profile is improved.

Description

technical field [0001] The invention relates to a saturation correction method for temperature measurement of pure rotational Raman laser radar, which belongs to the field of measurement technology. Background technique [0002] The current lidar methods for atmospheric temperature detection mainly include Rayleigh scattering density method, differential absorption spectroscopy, vibrational Raman spectroscopy and pure rotational Raman spectroscopy. The Rayleigh scattering density method is based on the dependence relationship between the Rayleigh scattering intensity and the atmospheric molecular density to invert the atmospheric molecular density. The applicable condition is clean air, and the atmospheric transmittance function is considered to be approximately 1. The concentration of aerosols makes it applicable to the upper atmosphere above 30 kilometers. Differential absorption spectroscopy is based on the absorption spectrum of oxygen, which requires two laser beams wi...

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Problems solved by technology

The German RAMSES radar system considers the use of layered acquisition at the height level to avoid saturation. Different acquisition systems are used for the near-surface layer and the upper layer, and different attenuation sheets are used at the same time, so as to ensure the signal-to-noise At the same time, it can effectively reduce the incidence of saturation phenomenon, but the defect of this method is that the measurement of the atmospheric temperature near the ground is not accurate

In addition, NASA's GSFC and CNRS radar systems use saturation correction. The GSFC system relies on the time resolution of the system, while the CNRS system relies on the maximum counting rate of the detection system. These two The parameters are difficult to obtain accurately in actual experiments, so the measurement error of the near-surface atmospheric temperature is relatively large

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