Long-term trend of CH₄ at northern mid-latitudes: Comparison between ground-based infrared solar and surface sampling measurements

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• 作者：Curtis P. Rinsland ; Aaron Goldman ; James W. Elkins ; Linda S. Chiou ; James W. Hannigan ; Stephen W. Wood ; Emmanuel Mahieu and Rodolphe Zander
• 关键词：Remote sensing ; Troposphere ; Atmospheric chemistry ; Methane
• 刊名：Journal of Quantitative Spectroscopy and Radiative Transfer
• 出版年：2006
• 期刊代码：70_00224073
• 类别：ch
• 出版时间：February 2006
• 卷：97
• 期：3
• 页码：457-466
• 文件大小：396 K

摘要

We report average tropospheric w the MathML source">CH₄ volume mixing ratios retrieved from a 27 year time series of high spectral resolution infrared solar absorption measurements recorded between May 1977 and July 2004 at the US National Solar Observatory station on Kitt Peak (, 2.09 km altitude) and their comparison with surface in situ sampling measurements recorded between 1983 and 2004 at the Climate Monitoring and Diagnostics Laboratory (CMDL) station at Niwot Ridge, Colorado (, 3013 m altitude). The two measurement sets therefore overlap for the 1983–2004 time period. An average tropospheric volume mixing ratios of ( per unit volume) has been derived from the solar absorption time series with a best-fit increase rate trend equal to w the MathML source">8.26±2.20 ppbv w the MathML source">yr^-1 in 1983 decreasing to w the MathML source">1.94±3.69 ppbv w the MathML source">yr^-1 in 2003. The CMDL measurements also show a continuous long-term w the MathML source">CH₄ volume mixing ratio rise, with subsequent slowing down. A mean ratio of the retrieved average tropospheric volume mixing ratio to the CMDL volume mixing ratio for the overlapping time period of w the MathML source">1.038±0.034 indicates agreement between both data sets within the quantified experimental errors.