Observations of tropospheric trace gases by ground-based high resolution FT-IR spectrometer

利用地面红外太阳光谱反演了对流层中一氧化碳（CO）、乙烷（C_2H_6）、乙炔（C_2H_2）和氰化氢（HCN）的柱量和混合比。用高光谱分辨率傅立叶变换红外（FTIR）光谱仪在北方Moshiri（44.4°N）和Rikubetsu（43.5°N）记录了光谱。结果表明，日本北部对流层中4种分子的含量具有显著的季节变化，CO、C_2H_6和C_2H_2在冬春季（2 - 4月）和HCN在夏季（5 - 7月）分别达到最大值。在观测期间，偶见四种分子对流层浓度同时增强，可能是由于相同的来源。对流层中CO、C_2H_6和C_2H_2的含量具有良好的相关性，说明它们具有相似的来源和稀释过程。轨迹计算和全球火灾地图显示，亚洲大陆生物质燃烧的排放物向东输送到日本北部。1995年5月至2000年6月，对流层CO、C_2H_6和C_2H_2的下降趋势分别为（-2.10±0.30）、（-2.53±0.30）和（-3.99±0.57）% /yr，而HCN的下降趋势（-0.93±0.49）%/yr不显著。由于平流层O_3吸收太阳紫外线辐射，1980年代中期以来全球平流层O_3的耗竭导致地球表面太阳紫外线辐射增加。在日本北部观测到的对流层CO、C_2H_6和C_2H_2的负趋势可能是由于太阳紫外线辐射通过与OH的光化学反应而增加所致。此外，1995年5月至2000年6月在日本北部观测到的对流层co、C_2H_6和C_2H_2呈下降趋势的另一个原因可能是过去10年生物质燃烧和人为源排放这些气体的减少。

Tropospheric column amounts and mixing ratios of carbon monoxide (CO), ethane (C_2H_6), acetylene (C_2H_2), and hydrogen cyanide (HCN) were retrieved from ground-based infrared solar spectra. The spectra were recorded with high spectral resolution Fourier Transform Infrared (FTIR) spectrometers at Moshiri (44.4°N) and Rikubetsu (43.5°N) in northern.The retrievals show significant seasonal variations in the tropospheric content of the four molecules over northern Japan with maxima in winter-spring (February-April) for CO, C_2H_6 and C_2H_2 and in summer (May-July) for HCN.Simultaneous enhancements of the tropospheric concentration of the four molecules were occasionally observed during the observational period, possibly due to the same sources. Good correlations among the tropospheric amounts of CO, C_2H_6, and C_2H_2 indicated that they had similar sources and underwent similar processes of dilution. Trajectory calculations and global fire maps revealed that emissions of biomass burning on the Asian continent were transported eastward to northern Japan. Decreasing trends in tropospheric CO, C_2H_6, and C_2H_2 from May 1995 to June 2000 were found to be (-2.10±0.30), (-2.53±0.30), and (-3.99±0.57)%yr, respectively, while the trend of (-0.93±0.49)%/yr in HCN was not significant. Since stratospheric O_3 absorbs the solar UV radiation, the depletion of global stratospheric O_3 since mid-1980s resulted in an increase of the solar UV radiation on the earth surface. It is appear that the observed negative trends in tropospheric CO, C_2H_6, and C_2H_2 over northern Japan should be due to the increase in the solar UV radiation through the photochemical reactions with OH.In addition, reduced emissions of these gases from biomass burning and anthropogenic sources in the past decade would be another reason for the decreasing trends in troposphericCO, C_2H_6, and C_2H_2 observed in northern Japan from May 1995 to June 2000.