THE GROWTH-RATE AND DISTRIBUTION OF ATMOSPHERIC METHANE
THE GROWTH-RATE AND DISTRIBUTION OF ATMOSPHERIC METHANE
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DOI：
10.1029/94jd01245
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发表时间：
1994-08-20
影响因子：
4.4
通讯作者：
MASARIE, KA
中科院分区：
文献类型：
--
作者：
DLUGOKENCKY, EJ;STEELE, LP;MASARIE, KA
从 1983 年到 1992 年，大约每周从全球分布的站点网络收集空气样本，测量甲烷含量。站点的纬度范围为南纬 90 度到北纬 82 度。所有样品均通过气相色谱法进行分析，并在科罗拉多州博尔德的国家海洋和大气管理局气候监测和诊断实验室进行火焰电离检测，并根据单一校准尺度引用测量结果。测量的估计精度为 +/-0.2%。具有明显采样或分析错误或似乎受到当地 CH4 源污染的样品被识别并排除在数据分析之外。数据显示，甲烷存在强烈的南北梯度，最北端和最南端采样点之间的年平均差异约为 140 ppb。南部高纬度地区的甲烷时间序列具有相对简单的季节周期，在夏末至初秋期间达到最小值，几乎可以肯定其光化学破坏的季节性占主导地位。典型的季节性周期幅度约为 30 ppb。由于 CH4 源和汇以及大气传输之间的相互作用，北半球地点的季节周期比南半球地点复杂。北半球高纬度地区的季节周期振幅约为南半球高纬度地区观测到的季节周期振幅的两倍。夏威夷岛 3397 米处的年平均甲烷混合比比海平面低约 1%。趋势是在网络中的每个站点和全球范围内确定的。在这些测量期间，全球平均甲烷混合比的平均增量为 (11.1 +/- 0.2) ppb yr-1。全球范围内，甲烷的增长率从 1983 年的约 13.5 ppb yr-1 下降到 1991 年的约 9.3 ppb yr-1。1992 年北半球的甲烷增长率接近于零。给出了近十年来甲烷增长率长期缓慢下降和1992年北半球增长率快速变化的各种可能性。最可能的解释是甲烷来源的变化直接受到人类活动（例如化石燃料生产）的影响。
Methane WaS Measured in air samples collected approximately weekly from a globally distributed network of sites from 1983 to 1992. Sites range in latitude from 90-degrees-S to 82-degrees-N. All samples were analyzed by gas chromatography, with flame ionization detection at the National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory in Boulder, Colorado, and the measurements were referenced against a single calibration scale. The estimated precision of the measurements is +/-0.2%. Samples which had clear sampling or analytical errors, or which appeared to be contaminated by local CH4 SourCeS, were identified and excluded from the data analysis. The data reveal a strong north-south gradient in methane with an annual mean difference of about 140 ppb between the northernmost and southernmost sampling sites. Methane time series from the high southern latitude sites have a relatively simple seasonal cycle with a minimum during late summer-early fall, almost certainly dominated by the seasonality in its photochemical destruction. Typical seasonal cycle amplitudes there are about 30 ppb. Seasonal cycles at sites in the northern hemisphere are complex when compared to sites in the southern hemisphere due to the interaction among CH4 sources and sinks, and atmospheric transport. Seasonal cycle amplitudes in the high north are about twice those observed in the high southern hemisphere. Annual mean methane mixing ratios were approximately 1% lower at 3397 m than at sea level on the island of Hawaii. Trends were determined at each site in the network and globally. The average increase in the globally averaged methane mixing ratio over the period of these measurements is (11.1 +/- 0.2) ppb yr-1. Globally, the growth rate for methane decreased from approximately 13.5 ppb yr-1 in 1983 to about 9.3 ppb yr-1 in 1991. The growth rate of methane in the northern hemisphere during 1992 was near zero. Various possibilities for the long-term, slow decrease in the methane growth rate over the last decade and the rapid change in growth rate in the northern hemisphere in 1992 are given. The most likely explanation is a change in a methane source influenced directly by human activities, such as fossil fuel production.