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首页> 外文学位 >Column abundances of carbon dioxide and methane retrieved from ground-based near-infrared solar spectra.
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Column abundances of carbon dioxide and methane retrieved from ground-based near-infrared solar spectra.

机译：从地面近红外太阳光谱中检索到的二氧化碳和甲烷的色谱柱丰度。

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To predict future climate change, we must accurately predict future atmospheric concentrations of CO2 and CH4. The current budget has typically been inferred from topdown analyses of measurements from a global network of surface sites. These measurements are highly accurate, but have limited spatial coverage. In addition, accurate knowledge of local planetary boundary layer dynamics is necessary to determine fluxes.;Column measurements, defined as the vertical integral of gas concentration, can complement the existing in situ network. Because column measurements sample a larger portion of the atmosphere, they exhibit less variability than surface data, while retaining information about surface fluxes. Column measurements are not influenced by planetary boundary layer dynamics, and do not suffer from the resulting correlation between exchange and transport.;An automated observatory for measuring ground-based column abundances of CO2, CH4, and O2 is described. Near-infrared spectra of the direct sun are obtained from 3,900--15,600 cm -1 by a Bruker 125HR Fourier transform spectrometer. The observatory was assembled in Pasadena, California and then permanently deployed to Northern Wisconsin during May 2004, Under clear sky conditions, retrieved column CO 2 abundances demonstrate ∼0.1% precision. Comparison of these column measurements with eight aircraft profiles of in situ CO2 recorded during summer 2004 shows a small bias, but an excellent correlation.;The observed secular increase and seasonal amplitude of column-average CO2 observed during the period of May 2004--March 2006 is 1.8 ppmv yr-1 and 11 ppmv, consistent with theoretical predictions that the measurements will be representative of Northern Hemisphere CO2 exchange over seasonal timescales. Comparisons with eddy covariance measurements show that the column measurements have potential for directly observing CO 2 exchange, but that this ability is constrained by the difficulty in accounting for atmospheric transport.;Finally, the use of near-infrared spectral analysis is extended to observations of tropospheric column-average CH4 concentrations. By employing a stratospheric "slope equilibrium" relationship between CH4 and HF, the varying contribution of stratospheric CH4 to the total column is inferred. This method is used to determine tropospheric column-average CH4 VMRs from near-infrared solar absorption spectra recorded at the Kitt Peak National Solar Observatory during 1977--1995.
机译：要预测未来的气候变化，我们必须准确地预测未来大气中的CO2和CH4浓度。当前预算通常是根据对地面站点的全球网络进行的自上而下的测量分析得出的。这些测量非常准确，但空间覆盖范围有限。另外，需要准确了解局部行星边界层动力学来确定通量。列测量（定义为气体浓度的垂直积分）可以补充现有的原位网络。由于柱测量值对大气的较大部分进行采样，因此与地面数据相比，它们显示的变异性较小，同时保留了有关表面通量的信息。色谱柱的测量不受行星边界层动力学的影响，并且不受交换和传输之间的相关关系的影响。；描述了一种用于测量地面上CO2，CH4和O2的柱丰度的自动观测台。通过Bruker 125HR傅立叶变换光谱仪从3,900--15,600 cm -1获得直射太阳的近红外光谱。该天文台在加利福尼亚州帕萨迪纳组装，然后于2004年5月永久部署到威斯康星州北部。在晴朗的天空条件下，回收的CO 2柱丰度显示出约0.1％的精度。将这些色谱柱测量值与2004年夏季记录的八种飞机原位CO2曲线进行比较，显示出较小的偏差，但相关性极好.2004年5月至3月期间观测到的色谱柱平均CO2的长期升高和季节性幅度2006年为1.8 ppmv yr-1和11 ppmv，与理论预测一致，即该测量将代表北半球季节性时间尺度上的CO2交换。与涡动协方差测量的比较表明，柱测量具有直接观测CO 2交换的潜力，但这种能力受到难以解释大气传输的限制。最后，近红外光谱分析的应用扩展到了对对流层平均CH4浓度。通过使用CH4和HF之间的平流层“斜率平衡”关系，可以推断出平流层CH4对整个色谱柱的变化贡献。该方法用于根据1977--1995年基特峰国家太阳能天文台记录的近红外太阳吸收光谱确定对流层平均CH4 VMR。

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