Role of OH variability in the stalling of the global atmospheric CH4 growth rate from 1999 to 2006
Role of OH variability in the stalling of the global atmospheric CH4 growth rate from 1999 to 2006
复制标题
DOI：
10.5194/acp-16-7943-2016
复制
发表时间：
2015-04
影响因子：
6.3
通讯作者：
J. McNorton;M. Chipperfield;M. Gloor;Chris Wilson;W. Feng;G. Hayman;M. Rigby;P. Krummel;S. O'Doherty;R. Prinn;R. Weiss;D. Young;E. Dlugokencky;S. Montzka
中科院分区：
文献类型：
--
作者：
J. McNorton;M. Chipperfield;M. Gloor;Chris Wilson;W. Feng;G. Hayman;M. Rigby;P. Krummel;S. O'Doherty;R. Prinn;R. Weiss;D. Young;E. Dlugokencky;S. Montzka
抽象的。在过去20年中，大气甲烷浓度的增长在几年的时间尺度上表现出很大的变化。在1999年之前，全球平均甲烷浓度以每年6.0 ppb的速度增长，但在1999年至2006年的停滞期内，这一增长速度放缓至每年0.6 ppb。从2007年到2009年，增长率再次增加到4.9 ppb yr-1。增长率的这些变化通常归因于甲烷排放量的变化。我们已经使用了一个3-D的全球化学传输模型，驱动气象再分析和来自两个独立的网络CH 3CCl 3观测的全球平均羟基（OH）浓度的变化，调查这些CH 4的增长变化。该模型表明，1999年至2006年期间，甲烷大气损失的变化大大有助于抑制全球甲烷浓度相对于1999年前的趋势。这方面的最大因素是全球平均OH在几年时间尺度上的变化相对较小，CH 4向汇区的大气传输和大气温度的贡献较小。虽然排放量的变化可能是重要的停滞期间，这些结果意味着一个较小的变化，需要解释所观察到的甲烷趋势。OH变化对2007年之后CH 4重新增长的贡献无法用现有数据确定。
Abstract. The growth in atmospheric methane (CH4) concentrations over the past 2 decades has shown large variability on a timescale of several years. Prior to 1999 the globally averaged CH4 concentration was increasing at a rate of 6.0 ppb yr−1, but during a stagnation period from 1999 to 2006 this growth rate slowed to 0.6 ppb yr−1. From 2007 to 2009 the growth rate again increased to 4.9 ppb yr−1. These changes in growth rate are usually ascribed to variations in CH4 emissions. We have used a 3-D global chemical transport model, driven by meteorological reanalyses and variations in global mean hydroxyl (OH) concentrations derived from CH3CCl3 observations from two independent networks, to investigate these CH4 growth variations. The model shows that between 1999 and 2006 changes in the CH4 atmospheric loss contributed significantly to the suppression in global CH4 concentrations relative to the pre-1999 trend. The largest factor in this is relatively small variations in global mean OH on a timescale of a few years, with minor contributions of atmospheric transport of CH4 to its sink region and of atmospheric temperature. Although changes in emissions may be important during the stagnation period, these results imply a smaller variation is required to explain the observed CH4 trends. The contribution of OH variations to the renewed CH4 growth after 2007 cannot be determined with data currently available.