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

从地面红外太阳光谱反演了对流层中一氧化碳(CO)、乙烷(C2H6)、乙炔(C2H2)和氰化氢(HCN)的柱数和混合比。用高光谱分辨率傅里叶变换红外光谱仪在日本北部的莫什里(44.4°N)和陆北(43.5°N)记录了这四种分子的光谱。结果表明，这四种分子在日本北部对流层中的含量有显著的季节变化，其中CO、C2H6和C2H2的含量在冬春季(2-4月)达到最大值，而HCN的含量在夏季(5-7月)达到最大值。对流层CO、C_2H_6和C_2H_2之间的良好相关性表明，它们具有相似的来源和相似的稀释过程。轨迹计算和全球火灾地图显示，亚洲大陆燃烧生物质的排放向东输送到日本北部。从1995年5月到2000年6月，对流层CO、C2H6和C2H2的下降趋势分别为(-2.10±0.30)%、(-2.53±0.30)%和(-3.99±0.57)%，而HCN的下降趋势不明显。由于平流层臭氧吸收了太阳的紫外线辐射，20世纪80年代中期以来全球平流层臭氧的枯竭导致了地球表面太阳紫外线辐射的增加。观测到的日本北部对流层CO、C_2H_6和C_2H_2的负趋势可能是由于与O H的光化学反应使太阳紫外线辐射增加所致。此外，生物质燃烧和人为来源这些气体排放量的减少也是1995年5月至2000年6月日本北部对流层CO、C_2H_6和C_2H_2下降趋势的另一个原因。

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.