闪电通道温度诊断中观测距离的影响

利用无狭缝光栅摄谱仪获得了青海高原地区云对地闪电首次回击过程的光谱,运用比尔-朗伯定律,考虑传播过程中谱线强度的衰减,计算讨论了观测距离对通道温度诊断结果的影响.结果表明,不同观测距离下得到的光谱诊断放电通道温度,其结果有一定差异;远距离观测得到的温度小于近距离观测的结果;观测距离越远,所得温度的误差越大.因此,在远距离观测的情况下,修正更为重要.由计算结果,得到了温度修正的半经验公式,由此,可以扣除观测距离对闪电通道温度诊断结果的影响.

Influence of the observation distance on the lightning channel temperature studied by means of spectroscopic diagnosis

The spectra for first return strokes of cloud-to-ground lightning discharge were obtained by a slit-less spectrograph at the Qinghai plateau of China. In this paper, the effect of the observation distance on diagnosis results of channel temperature was calculated and discussed by applying the Beer-Lambert law and considering the attenuation of spectral line intensity in transmission. Results show that there is some difference in channel temperature obtained at different observation distances. The observation distance is further enlarged, then the temperature obtained will be lower. Furthermore, at further increased distance we take observation, the bigger the error will be. So the correction for the temperature is more important for longer observation distance. According to our calculation and analysis, a semi-empirical formula has been obtained, which shows a relationship between the lightning channel temperature and the observation distance. The influence of the observation distance on lightning channel temperature could be eliminated by using the semi-empirical formula.
Keywords： lightning spectra observation distance channel temperature Beer-Lambert law