| Autor: |
Nevison, Cynthia D., Liang, Qing, Newman, Paul A., Stephens, Britton B., Dutton, Geoff, Lan, Xin, Commane, Roisin, Gonzalez, Yenny, Kort, Eric |
| Předmět: |
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| Zdroj: |
Atmospheric Chemistry & Physics; 2024, Vol. 24 Issue 18, p10513-10529, 17p |
| Abstrakt: |
The literature presents different views on how the stratosphere influences variability in surface nitrous oxide (N 2 O) and on whether that influence is outweighed by surface emission changes driven by the El Niño–Southern Oscillation (ENSO). These questions are investigated using a chemistry–climate model with a stratospheric N 2 O tracer; surface and aircraft-based N 2 O measurements; and indices for ENSO, polar lower stratospheric temperature (PLST), and the stratospheric quasi-biennial oscillation (QBO). The model simulates well-defined seasonal cycles in tropospheric N 2 O that are caused mainly by the seasonal descent of N 2 O-poor stratospheric air in polar regions with subsequent cross-tropopause transport and mixing. Similar seasonal cycles are identified in recently available N 2 O data from aircraft. A correlation analysis between the N 2 O atmospheric growth rate (AGR) anomaly in long-term surface monitoring data and the ENSO, PLST, and QBO indices reveals hemispheric differences. In the Northern Hemisphere, the surface N 2 O AGR is negatively correlated with winter (January–March) PLST. This correlation is consistent with an influence from the Brewer–Dobson circulation, which brings N 2 O-poor air from the middle and upper stratosphere into the lower stratosphere with associated warming due to diabatic descent. In the Southern Hemisphere, the N 2 O AGR is better correlated to QBO and ENSO indices. These different hemispheric influences on the N 2 O AGR are consistent with known atmospheric dynamics and the complex interaction of the QBO with the Brewer-Dobson circulation. More airborne surveys extending to the tropopause would help elucidate the stratospheric influence on tropospheric N 2 O, allowing for better understanding of surface sources. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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