Tritiated water vapor in the stratosphere: Vertical profiles and residence time
Tritiated water vapor in the stratosphere: Vertical profiles and residence time
复制标题
平流层中的氚水蒸气：垂直剖面和停留时间
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
W. Pollock
中科院分区：
文献类型：
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作者：
D. Ehhalt;F. Rohrer;S. Schauffler;W. Pollock
[1]重新分析了美国国家大气研究中心1975至1983年间对平流层水蒸气中氚含量的历史测量和部分未发表的测量结果。得到的T含量垂直分布主要在北纬32°，在20公里以上随海拔变化不大，但随时间有较强的衰减。这种衰变是1963年前高产额热核装置大气试验向平流层注入大量T的结果，似乎以5.12年的单一e倍时间进行。对平流层HTO的放射性衰变和平流层H2O随时间的增加进行了校正，得到平流层HTO的衰变时间为7.7±2.0年。这种衰变时间完全是由于HTO输送到对流层，比这些高度的平流层空气的年龄或可接受的平流层停留时间值要长得多。通过将HTO衰变时间解释为平流层输送方程最长寿命模式的特征值，讨论并解决了这些差异。这一特征应该在模拟平流层输送时提供一个有用的约束。
[1] The historic and partly unpublished measurements of the tritium content in stratospheric water vapor made at the National Center for Atmospheric Research between 1975 and 1983 are reanalyzed. The resulting vertical profiles of the T content, mainly at 32°N latitude, show little variation with altitude above 20 km but a strong decay with time. This decay is a consequence of the large T injections into the stratosphere by the atmospheric tests of high-yield thermonuclear devices prior to 1963 and seems to proceed with a single e-fold time of 5.12 years. Correcting for the radioactive decay of HTO within the stratosphere and for a temporal increase in stratospheric H2O, we obtain a decay time for stratospheric HTO of 7.7 ± 2.0 years. This decay time, which is solely due to the transport of HTO into the troposphere, is much longer than the age of stratospheric air at these altitudes or the accepted values for stratospheric residence times. The differences are discussed and resolved by interpreting the HTO decay time as the Eigentime of the longest-lived mode of the stratospheric transport equations. This Eigentime should provide a useful constraint in modeling stratospheric transport.