Observed changes in stratospheric circulation: decreasing lifetime of N 2 O, 2005–2021

[摘要] Using Aura Microwave Limb Sounder satellite observationsof stratospheric nitrous oxide (N 2 O), ozone, and temperature from 2005through 2021, we calculate the atmospheric lifetime of N 2 O to bedecreasing at a rate of −2.1   ±  1.2 %/decade. This decrease is occurring because the N 2 O abundances in the middle tropical stratosphere, where N 2 O is photochemically destroyed, are increasing ata faster rate than the bulk N 2 O in the lower atmosphere. The causeappears to be a more vigorous stratospheric circulation, which modelspredict to be a result of climate change. If the observed trends in lifetime and implied emissions continue, then the change in N 2 O over the21st century will be 27 % less than those projected with a fixed lifetime, and the impact on global warming and ozone depletion will beproportionately lessened. Because global warming is caused in part byN 2 O, this finding is an example of a negative climate–chemistry feedback.

[学科分类] 医学（综合）