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Changes in Anthropogenic Precursor Emissions Drive Shifts in the Ozone Seasonal Cycle Throughout the Northern Midlatitude Troposphere

Authors :
Henry Bowman
Steven T. Turnock
Susanne E Bauer
Konstantinos Tsigaridis
Makoto Deushi
Naga Oshima
Fiona M O'Connor
Larry Horowitz
Tongwen Wu
Jie Zhang
Dagmar Kubistin
David D Parrish
Source :
Atmospheric Chemistry and Physics. 22(5)
Publication Year :
2022
Publisher :
United States: NASA Center for Aerospace Information (CASI), 2022.

Abstract

Simulations by six Coupled Model Intercomparison Project Phase 6 (CMIP6) Earth system models indicate that the seasonal cycle of baseline tropospheric ozone at northern midlatitudes has been shifting since the mid-20th century. Beginning in ∼ 1940, the magnitude of the seasonal cycle increased by ∼10 ppb (measured from seasonal minimum to maximum), and the seasonal maximum shifted to later in the year by about 3 weeks. This shift maximized in the mid-1980s, followed by a reversal – the seasonal cycle decreased in amplitude and the maximum shifted back to earlier in the year. Similar changes are seen in measurements collected from the 1970s to the present. The timing of the seasonal cycle changes is generally concurrent with the rise and fall of anthropogenic emissions that followed industrialization and the subsequent implementation of air quality emission controls. A quantitative comparison of the temporal changes in the ozone seasonal cycle at sites in both Europe and North America with the temporal changes in ozone precursor emissions across the northern midlatitudes found a high degree of similarity between these two temporal patterns. We hypothesize that changing precursor emissions are responsible for the shift in the ozone seasonal cycle; this is supported by the absence of such seasonal shifts in southern midlatitudes where anthropogenic emissions are much smaller. We also suggest a mechanism by which changing emissions drive the changing seasonal cycle: increasing emissions of NOx allow summertime photochemical production of ozone to become more important than ozone transported from the stratosphere, and increasing volatile organic compounds (VOCs) lead to progressively greater photochemical ozone production in the summer months, thereby increasing the amplitude of the seasonal ozone cycle. Decreasing emissions of both precursor classes then reverse these changes. The quantitative parameter values that characterize the seasonal shifts provide useful benchmarks for evaluating model simulations, both against observations and between models.

Subjects

Subjects :
Meteorology And Climatology

Details

Language :
English
ISSN :
16807324 and 16807316
Volume :
22
Issue :
5
Database :
NASA Technical Reports
Journal :
Atmospheric Chemistry and Physics
Notes :
509496.02.08.04.24, , 80NSSC20M0282
Publication Type :
Report
Accession number :
edsnas.20220004426
Document Type :
Report
Full Text :
https://doi.org/10.5194/acp-22-3507-2022