Observational Research of Stratospheric Hydroxyle

氢氧化物是中层大气中最重要的次要组分之一，因为它具有很高的反应性；然而，由于其丰度极低，迄今只有少数几个测量结果被报道。在这项研究中，我们成功地利用紫外光谱定量了平流层羟基柱，以太阳为光源测量了A^2SIGMA-X^2II(0，0)带1P_1和3Q_1的308 nm吸收线。测量系统由1.5米双通光栅单色仪、带有一级MCP的线性图像传感器、太阳跟踪器和0.5米望远镜组成，安装在东京大学位于东京市中心的本乡校区。该系统的光谱纯度为1.2 pM，略大于羟基线的多普勒宽度。困难来自于这一地区的太阳光谱充满了太阳吸收线，这些吸收线比地球上的羟基吸收特征强得多。在本研究中，我们使用了…更多地利用太阳自转引起的太阳光谱的多普勒频移来区分陆地吸收和太阳特征，这是本研究最具特色的一点。通过比较太阳圆盘东西边缘的太阳光谱，有可能抵消太阳结构，使地面吸收更加突出。自1992年5月以来，在经历了太阳跟踪不准确、冷却系统能力不足、光学系统退化和机械温度漂移等各种故障后，获得了良好的数据。夏季和冬季中午测得的羟基垂直柱分别为6×10^；13；cm；-2；和4×10；lt；13；-2；；夏季傍晚，当太阳天顶角达到60ﾟ时，羟基垂直柱减少到4×10^；这种行为可以用一维化学扩散模型粗略地再现；我们对中层大气光化学的理解与事实相差不远。较少

Hydroxide is one of the most important minor constituents in the middle atmosphere because of its high reactivity; however, only a few measurements have been reported so far because of its extremely small abundance. In this research, we succeeded to quantify the stratospheric hydroxyle column by UV spectroscopy to measure A^2SIGMA-X^2II (0,0) band 1P_1, and 3Q_1, absorption lines at 308 nm using the sun as a light source.The measuring system consists of a 1.5 m double-pass grating monochromator, a linear image sensor with a one-stage MCP, a sun-tracker and a 0.5 m telescope, and is set in Hongo campus of the University of Tokyo located at the central Tokyo City. The spectral purity of the system used is 1.2 pm which is a little larger than the Doppler width of the hydroxyle lines. Difficulty comes from the fact that the solar spectrum in this region is filled with solar absorption lines which are much stronger than the terrestrial hydroxyle absorption features. In this research we util … More ized the Doppler shift of the solar spectrum due to the solar rotation in discriminating the terrestrial absorptions from the solar features; this is the most distinctive point of this research. By comparing the solar spectra measured on the east and west edges of the solar disk, it is possible to cancel out the solar structure and make the terrestrial absorption much more prominent.Good data have been obtained since May 1992 after various troubles such as inaccurate sun tracking, insufficient ability of the cooling system, degradation of the optics and temperature drift of the mechanics. The measured hydroxyle vertical columns at noon in summer and winter are 6 x 10^<13> cm^<-2> and 4 x 10^<13> cm^<-2>, respectively, and decreases to 4 x 10^<13> cm^<-2> in the summer evening when the solar zenith angle reaches 60ﾟ. This behavior can roughly be reproduced with a one- dimensional chemical-diffusive model; our understanding of the middle atmosphere photo-chemistry is found to be not far from the truth. Less