Evaluation and Improvement of Lidar Performance Based on Temporal and Spatial Variance Calculation

Fei Gao,Li Wang,Tingyao He,Dengxin Hua,Qingsong Zhu,Samo Stanič,Longlong Wang,Xinxin Xu

doi:10.3390/app9091786

Fei Gao, Li Wang + Show 6 more

Open Access

https://doi.org/10.3390/app9091786

Copy DOI

Abstract

Poisson distributions have the characteristic of equality between their variance and mean values. By constructing a calculation model of the temporal variance and spatial variance, the relationship between the variance and mean values of lidar analog data and photon-counting data can be analyzed. The calculation results show that the photon-counting data from far field have the distribution property of equality between the variances and the corresponding mean values, while the analog data for the whole probing traces do not. In this paper, by analyzing the distribution properties of the spatial variance and temporal variance of lidar data, the dead time of photon-counting data was estimated, and the threshold voltage of the photon-counting system and the linear working range of photomultiplier tube were evaluated. The results show that the linear working range of the high voltage for the photomultiplier tube in the ultraviolet elastic scanning lidar is between −500 V and −1000 V, and the dead time and threshold voltage of the photon-counting system in the Licel transient recorder are 3.488 ns and 1.20 mV, respectively. Meanwhile, a novel gluing method between analog data and photon-counting data is presented, based on the calculation results of the variance distribution of lidar data. The linear transfer coefficients were determined by minimizing the differences between the variance and mean of the transformed photon-counting data in the near filed with high signal to noise ratio. The glued data were distributed to express the atmospheric conditions uniformly.

Highlights

Lidar has proven to be an active remote sensing tool for atmospheric sciences and environmental research applications, one which can provide the atmospheric temperature, humidity, wind velocity, and aerosol optical properties by analyzing the spectra and intensity of laser echo signals [1].The multi-wavelength polarization can be used to measure the depolarization ratio and microphysical properties by analyzing the variation of the polarization and the intensity of the lidar returns, and plays an important role in evaluating cirrus cloud and aerosol direct radiative effects [2,3]
In Raman lidar or high-spectral-resolution lidar with multi-channels, the intensities of the separated spectral radiant flux in different channels are different, and the photomultiplier tube (PMT) may be set with different high voltages to achieve the optimal detection performance
To make the received lidar returns normalized in the procedure of data retrieval, the evaluation of the linear working range of the PMT is necessary in the construction of the lidar system

Summary

Introduction

Lidar has proven to be an active remote sensing tool for atmospheric sciences and environmental research applications, one which can provide the atmospheric temperature, humidity, wind velocity, and aerosol optical properties by analyzing the spectra and intensity of laser echo signals [1].The multi-wavelength polarization can be used to measure the depolarization ratio and microphysical properties by analyzing the variation of the polarization and the intensity of the lidar returns, and plays an important role in evaluating cirrus cloud and aerosol direct radiative effects [2,3]. Lidar has proven to be an active remote sensing tool for atmospheric sciences and environmental research applications, one which can provide the atmospheric temperature, humidity, wind velocity, and aerosol optical properties by analyzing the spectra and intensity of laser echo signals [1]. Vibrational Raman lidar can be used to measure aerosol extinction, water vapor, and carbon dioxide concentration by extracting the vibrational Raman spectra of nitrogen, water vapor, and carbon dioxide [4,5]. Rotational Raman lidar can be used to measure atmospheric temperature, as the intensity of an individual pure rotational Raman line of nitrogen and oxygen depends on temperature, due to.

Results

Discussion

Conclusion