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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >EVALUATION OF SOURCE GAS LIFETIMES FROM STRATOSPHERIC OBSERVATIONS
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EVALUATION OF SOURCE GAS LIFETIMES FROM STRATOSPHERIC OBSERVATIONS

机译：从球气观测评价气源寿命

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Simultaneous in situ measurements of the long-lived trace species N2O, CH4, CFC-12, CFC-113, CFC-11, CCl4, CH3CCl3, H-1211, and SF6 were made in the lower stratosphere and upper troposphere on board the NASA ER-2 high-altitude aircraft during the 1994 campaign Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft. The observed extratropical tracer abundances exhibit compact mutual correlations that show little interhemispheric difference or seasonal variability except at higher altitudes in southern hemisphere spring. The environmental impact of the measured source gases depends, among other factors, on the rate at which they release ozone-depleting chemicals in the stratosphere, that is, on their stratospheric lifetimes. We calculate the mean age of the air from the SF6 measurements and show how stratospheric lifetimes of the other species may be derived semiempirically from their observed gradients with respect to mean age at the extratropical tropopause. We also derive independent stratospheric lifetimes using the CFC-11 lifetime and the slopes of the tracer's correlations with CFC-11. In both cases, we correct for the influence of tropospheric growth on stratospheric tracer gradients using the observed mean age of the air, time series of observed tropospheric abundances, and model-derived estimates of the width of the stratospheric age spectrum. Lifetime results from the two methods are consistent with each other. Our best estimates for stratospheric lifetimes are 122 +/- 24 years for N2O, 93 +/- 18 years for CH4, 87 +/- 17 years for CFC-12, 100 +/- 32 years for CFC-113, 32 +/- 6 years for CCl4, 34 +/- 7 years for CH3CCl3, and 24 +/- 6 years for H-1211. Most of these estimates are significantly smaller than currently recommended lifetimes, which are based largely on photochemical model calculations. Because the derived stratospheric lifetimes are identical to atmospheric lifetimes for most of the species considered, the shorter lifetimes would imply a faster recovery of the ozone layer following the phaseout of industrial halocarbons than currently predicted. [References: 82]
机译：在NASA的平流层下部和对流层上部同时对长寿命的痕量N2O，CH4，CFC-12，CFC-113，CFC-11，CCl4，CH3CCl3，H-1211和SF6进行了原位测量ER-2高空飞机在1994年的“评估南流层飞机效果的机载南半球臭氧实验/测量”活动中。观测到的温带示踪剂丰度显示出紧凑的相互关系，除了南半球春季较高的海拔外，几乎没有半球间差异或季节性变化。除其他因素外，所测量的原料气对环境的影响取决于它们在平流层中释放消耗臭氧的化学物质的速率，即平流层的寿命。我们通过SF6测量值计算了空气的平均年龄，并显示了其他物种的平流层寿命如何从它们的观测梯度相对于温带对流层顶平均年龄进行半经验推导。我们还使用CFC-11寿命以及示踪剂与CFC-11的相关关系的斜率来得出独立的平流层寿命。在这两种情况下，我们都使用观测到的平均空气年龄，观测到的对流层丰度的时间序列以及模型得出的平流层年龄谱宽度的估计值来校正对流层增长对平流层示踪剂梯度的影响。两种方法的寿命结果彼此一致。我们对平流层寿命的最佳估计是N2O为122 +/- 24年，CH4为93 +/- 18年，CFC-12为87 +/- 17年，CFC-113为100 +/- 32年，32 +/- -CCl4为6年，CH3CCl3为34 +/- 7年，H-1211为24 +/- 6年。这些估计中的大多数都大大小于当前建议的寿命，后者主要基于光化学模型计算。由于考虑到的大多数物种的平流层寿命与大气寿命相同，因此，较短的寿命意味着在淘汰工业卤代烃后，臭氧层的恢复速度将比目前预期的更快。 [参考：82]

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