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首页> 外文期刊>Atmospheric chemistry and physics >Analysis of CO2 mole fraction data: first evidence of large-scale changes in CO2 uptake at high northern latitudes
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Analysis of CO2 mole fraction data: first evidence of large-scale changes in CO2 uptake at high northern latitudes

机译：分析CO2摩尔分数数据：北高纬度地区大规模吸收CO2的第一个证据

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Atmospheric variations of carbon dioxide (CO2) mole fraction reflect changes in atmospheric transport and regional patterns of surface emission and uptake. Here we present a study of changes in the observed high northern latitude CO2 seasonal cycle. We report new estimates for changes in the phase and amplitude of the seasonal variations, indicative of biospheric changes, by spectrally decomposing multi-decadal records of surface CO2 mole fraction using a wavelet transform to isolate the changes in the observed seasonal cycle. We also perform similar analysis of the first derivative of CO2 mole fraction, Delta tCO2, that is a crude proxy for changes in CO2 flux. Using numerical experiments, we quantify the aliasing error associated with independently identifying trends in phase and peak uptake and release to be 10-25 %, with the smallest biases in phase associated with the analysis of Delta tCO(2). We report our analysis from Barrow, Alaska (BRW), during 1973-2013, which is representative of the broader Arctic region. We determine an amplitude trend of 0.09 +/- 0.02 ppmy r(-1), which is consistent with previous work. Using Delta tCO2 we determine estimates for the timing of the onset of net uptake and release of CO2 of 0.14 +/- 0.14 and 0.25 +/- 0.08 days yr(-1) respectively and a corresponding net uptake period of 0.11 +/- 0.16 days yr(-1), which are significantly different to previously reported estimates. We find that the wavelet transform method has significant skill in characterizing changes in the peak uptake and release. We find a trend of 0.65 +/- 0.34% yr(-1) (p < 0.01) and 0.42 +/- 0.34 % yr(-1) (p < 0.05) for rates of peak uptake and release respectively. Our analysis does not provide direct evidence about the balance between uptake and release of carbon when integrated throughout the year, but the increase in the seasonal amplitude of CO2 together with an invariant net carbon uptake period provides evidence that high northern latitude ecosystems are progressively taking up more carbon during spring and early summer.
机译：大气中二氧化碳（CO2）摩尔分数的变化反映了大气传输的变化以及地表排放和吸收的区域格局。在这里，我们对观测到的北纬高CO2季节周期的变化进行了研究。我们通过使用小波变换对观测到的季节性周期变化进行小波变换来对表面CO2摩尔分数的多年代记录进行频谱分解，从而报告季节性变化的相位和幅度变化（表明生物圈变化）的新估计值。我们还对CO2摩尔分数的一阶导数Delta tCO2进行了类似的分析，它是CO2通量变化的粗略替代。使用数值实验，我们可以量化与独立识别相位和峰值吸收和释放趋势相关的混叠误差，其为10-25％，与ΔtCO（2）分析相关的最小相位误差。我们在1973-2013年间报告了来自阿拉斯加巴罗（BRW）的分析，该分析代表了更广阔的北极地区。我们确定振幅趋势为0.09 +/- 0.02 ppmy r（-1），与先前的工作一致。使用Delta tCO2，我们确定净吸收和释放CO2的开始时间的估计值分别为yr（-1）0.14 +/- 0.14天和0.25 +/- 0.08天yr（-1），相应的净吸收时间为0.11 +/- 0.16天yr（-1）天，与以前报告的估算值明显不同。我们发现，小波变换方法在表征峰吸收和释放变化方面具有显着的技能。我们发现峰值吸收和释放速率分别为0.65 +/- 0.34％yr（-1）（p <0.01）和0.42 +/- 0.34％yr（-1）（p <0.05）。我们的分析并未提供有关全年整合后碳吸收与释放之间平衡的直接证据，但CO2的季节性幅度增加以及净碳吸收期不变提供了证据，表明北纬高海拔生态系统正在逐步吸收春季和初夏期间碳含量更高。

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