RML探测大气气溶胶波长指数的不确定分析

Uncertainty analysis of aerosol wavelength exponent measured by Raman-Mie lidars

为了提高喇曼-米散射激光雷达探测大气气溶胶波长指数的精确度,利用不确定度传递公式对其不确定性进行了详细的理论分析,并结合喇曼-米散射激光雷达在合肥西郊的实际探测例子进行了实验研究,计算了信号、大气透过率比值和散射比参考值的相对不确定度,在高度6km以下信号相对不确定度一般小于30%,透过率比的相对不确定度一般小于4%,散射比参考值相对不确定度大小则由参考值与实际值差异而定。结果表明,适当增大激光脉冲能量和延长信号采集累计时间、准确标定散射比参考值可有效减小喇曼-米散射激光雷达探测大气气溶胶波长指数的不确定性。

In order to improve the measuring accuracy of aerosol wavelength exponent measured by Raman-Mie lidar （ RML）, the uncertainty propagation formula was used to analyze the uncertainty in detail. The uncertainties of signal, transmission ratio and assumed scattering ratio Rc were calculated based on the data measured over the west suburb of the city of Hefei. Commonly, below 6km, assuming the relative uncertainty of reference value of the scattering ratio Rc was dfined by the difference between the reference and real valves, the uncertainty of the signal and the transmission ratio was less than 30% and 4% respectively. The analytical results showed that the uncertainty of aerosol wavelength exponent could be reduced by increasing pulsed laser energy, prolonging signal collecting time and more accurately demarcating assumed Rc.