Study on Variations in Stratospheric Ozone with Laser Heterodyne Spectroscopy

1. 研制了一种以可调谐二极管激光器为本振的用于大气痕量气体遥测的激光外差光谱仪。可调谐二极管激光外差光谱仪（TDLHS）的光谱分辨率为0.0013cm^<-1> (40MHz)或0.0027CM^<-1> (80MHz)，获得的太阳吸收光谱信噪比为300 ~ 600。TDLHS的这些性能是通过使用(1)具有衍射限制质量的透镜来实现信号光束和本振光束的精确对准，(2)可以在液氮温度（77K）下工作的二极管激光器来实现激光频率的高稳定性，以及通过改善(3)对反射本振激光束的隔离。数据分析与结果根据实测光谱反演了臭氧和氧化亚氮的体积混合比垂直分布。反演的体积混合比精度为2-7%，垂直分辨率为4-6km，具体取决于海拔高度。将臭氧的测定结果与多布森分光光度计和臭氧探空仪的测定结果进行了比较，将氧化亚氮的测定结果与采样法的测定结果进行了比较。两种比较结果吻合良好。未来计划TDLHS将进一步提高分辨率至0.0007cm^<-1> (20MHz)，进行与臭氧化学相关的痕量成分测量，以提高臭氧遥感探测的上限。

1. Development of a laser heterodyne spectrometer A laser heterodyne spectrometer using a tunable diode laser as a local oscillator has been developed for remote sounding of atmospheric trace gases. The spectral resolution of the tunable diode laser heterodyne spectrometer (TDLHS) is either 0.0013cm^<-1> (40MHz) or 0.0027CM^<-1> (80MHz) and the signa-to-noise ratio of the obtained solar absorption spectra is 300 - 600. These performance of the TDLHS has been realized by using (1) lenses with diffraction limited quality for an exact alignment of signal beam and local oscillator beam, and (2) a diode laser which can operate at liquid nitrogen temperature (77K) for high stability of the laser frequency, and by improving (3) isolation of the reflected local oscillator laser beam.2. Data analysis and results Vertical profiles of volume mixing ratio for both ozone and nitrous oxide were inverted from the observed spectra. The accuracy of the retrieved volume mixing ratio is 2-7% and the vertical resolution is 4-6km, depending on the altitude. The results for ozone were compared with the data obtained by Dobson spectro-photometers and an ozonesonde, and the results for nitrous oxide were compared with the data obtained by sampling method. Both comparison showed good coincidence.3. Future plan Measurements of trace constituents related to ozone chemistry will be carried out by the TDLHS with further improved resolution of 0.0007cm^<-1> (20MHz) in order to increase the upper bound of ozone remote sounding.