Recent Decline in Extratropical Lower Stratospheric Ozone Attributed to Circulation Changes

Wargan, Krzysztof; Orbe, Clara; Pawson, Steven; Ziemke, J. R.; Oman, Luke D.; Olsen, Mark A.; Coy, L.; Knowland, K. Emma

doi:10.1029/2018gl077406

Cited by 101 publications

(138 citation statements)

References 52 publications

(84 reference statements)

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“…Both of the models in this work are driven with the MERRA‐2 meteorological reanalysis, and both use versions of NASA's GMI chemical mechanism (Duncan et al, ; Nielsen et al, ). The first model (M2 GMI Replay; Orbe et al, ; Wargan et al, ) runs a previous version of the GMI mechanism, but uses the Replay technique (Orbe et al, ) to recalculate meteorological variables throughout the simulation. The purpose of the Replay technique is to reproduce (“replay”) the MERRA‐2 reanalysis with higher temporal resolution than archived MERRA‐2 products (which are used in the GMI CTM).…”

Section: Data and Model Outputmentioning

confidence: 99%

“…Some simulations incorporate observations into a general circulation model to produce an assimilated O 3 product, and in other simulations O 3 is calculated by a chemical mechanism that is driven by a historical meteorological reanalysis and emission inventories (the latter are the focus of this paper). Wargan et al (2018) used three different NASA Modern-Era Retrospective Analysis for Research Applications version 2 (MERRA-2; Gelaro et al, 2017) assimilation and model products and found downward LS O 3 trends from 1998 to 2016 similar to Ball et al (2018), although they attributed the trend mostly to a changing stratospheric circulation.…”

Section: Introduction: the Role For Models In Interpreting Ozone Trendsmentioning

confidence: 99%

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The Effects of a 1998 Observing System Change on MERRA‐2‐Based Ozone Profile Simulations

Stauffer

Thompson²,

Oman³

et al. 2019

JGR Atmospheres

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Model simulations of ozone (O3) driven by meteorological reanalyses are useful for filling observational gaps and interpreting observed O3 variability and trends. However, the transport circulation of reanalysis products is impacted by changes to the observing system (the data assimilated into the reanalyses). We examine the impacts of these changes on simulated O3 from two models, Global Modeling Initiative (GMI) Chemistry Transport Model (GMI CTM) and Modern‐Era Retrospective Analysis for Research Applications version 2 (MERRA‐2) GMI Replay (M2 GMI Replay) simulation, using observations from global ozonesondes (>50,000 profiles) and satellites from 1980 to 2016. Both models are constrained by meteorology from the NASA MERRA‐2 reanalysis, and both use versions of NASA's GMI chemical mechanism. We focus on an observing system change affecting simulated O3 after 1998, associated with the assimilation of temperature and humidity data from new microwave profiling satellites. A large post‐1998 O3 increase, mainly confined to 15–20‐km altitude, of ~10 Dobson units (DU) in midlatitudes occurs in the GMI CTM, worsening the bias compared to observations. In contrast, an increase in M2 GMI Replay simulation O3 of ~10 DU is observed only near −60° latitude, reducing the bias compared to observations. The GMI CTM O3 high biases display a Quasi‐Biennial Oscillation (QBO)‐like periodicity that result from excessive transport from the tropical stratosphere to the midlatitude lower stratosphere during the QBO westerly phase. We quantify O3 discontinuities caused by MERRA‐2 observing system changes and demonstrate how the MERRA‐2 Global Modeling Initiative Replay simulation dampens the effects of these changes and QBO‐driven artifacts on simulated lower stratospheric and total O3. We caution against using simulations driven by a reanalysis to derive multidecadal O3 trends, especially prior to 1998.

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Section: Data and Model Outputmentioning

confidence: 99%

Section: Introduction: the Role For Models In Interpreting Ozone Trendsmentioning

confidence: 99%

The Effects of a 1998 Observing System Change on MERRA‐2‐Based Ozone Profile Simulations

Stauffer

Thompson²,

Oman³

et al. 2019

JGR Atmospheres

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“…It is well-known that stratospheric ozone was decreasing since the 1980s, until the reverse of the trend emerged in the late 1990s that marks a turning point in the four-decade history of stratospheric ozone [7,8]. It has been shown in recent literature, e.g., [7,[9][10][11], that ozone in the upper stratosphere follows an upward trend, in contrast to negative, but smaller trends are seen in the lower stratosphere. The behavior of stratospheric ozone after the mid-1990s is dependent on (a) reduction in atmospheric halogens and (b) the slowing of ozone-depleting chemical processes due to the cooling of the stratosphere, which is associated with increases in GHGs.…”

Section: Introductionmentioning

confidence: 99%

Possible Effects of Greenhouse Gases to Ozone Profiles and DNA Active UV-B Irradiance at Ground Level

et al. 2020

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In this paper, we compare model calculations of ozone profiles and their variability for the period 1998 to 2016 with satellite and lidar profiles at five ground-based stations. Under the investigation is the temporal impact of the stratospheric halogen reduction (chemical processes) and increase in greenhouse gases (i.e., global warming) on stratospheric ozone changes. Attention is given to the effect of greenhouse gases on ultraviolet-B radiation at ground level. Our chemistry transport and chemistry climate models (Oslo CTM3 and EMAC CCM) indicate that (a) the effect of halogen reduction is maximized in ozone recovery at 1-7 hPa and observed at all lidar stations; and (b) significant impact of greenhouse gases on stratospheric ozone recovery is predicted after the year 2050. Our study indicates that solar ultraviolet-B irradiance that produces DNA damage would increase after the year 2050 by +1.3% per decade. Such change in the model is driven by a significant Atmosphere 2020, 11, 228 2 of 18 decrease in cloud cover due to the evolution of greenhouse gases in the future and an insignificant trend in total ozone. If our estimates prove to be true, then it is likely that the process of climate change will overwhelm the effect of ozone recovery on UV-B irradiance in midlatitudes.

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“…However, some studies have shown that stratospheric ozone concentrations over different regions along the same latitude exhibit different recovery rates. Over some regions, TCO even continues to decrease due to changes in local dynamical and chemical processes (Hood and Soukharev 2005;Zhang et al 2014Zhang et al , 2018Wargan et al 2018), suggesting that long-term ozone variations are highly longitude-dependent. Previous studies pointed out that the trends in the deviation of ozone from the zonal mean over some regions can reach and even exceed the zonal mean ozone trend at that latitude, particularly at 1 3 northern middle latitudes (e.g.…”

Section: Introductionmentioning

confidence: 99%

Zonally asymmetric trends of winter total column ozone in the northern middle latitudes

et al. 2018

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Using various satellite-based observations, a linear ozone transport model (LOTM), a chemistry-climate model (WACCM3) and an offline chemical transport model (SLIMCAT), zonally asymmetric trends of the total column ozone (TCO) in the northern middle latitudes during winter for the period 1979-2015 are analyzed and factors responsible for the trends are diagnosed. The results reveal that there are significant negative TCO trends over the North Pacific and positive TCO trends over the northwestern North America. The zonally asymmetric TCO trends are mainly contributed by the trends in partial column ozone in the upper troposphere and lower stratosphere (UTLS) which are closely related to the long-term changes of geopotential height in the troposphere. Furthermore, the trends of geopontential height in the UTLS are mainly modulated by pattern changes in the Arctic Oscillation (AO), the Cold Ocean-Warm Land (COWL) and the North Pacific (NP) index. Accordingly, the zonally asymmetric TCO trends can be largely reconstructed by the trends of the above three teleconnection patterns. Sea surface temperature (SST) changes over the Pacific Ocean and the Atlantic Ocean can also exert a significant contribution to the zonally asymmetric TCO trends through their influence on the COWL and NP patterns. In addition, chemical ozone loss partially offsets the positive trends in zonal TCO anomalies over Central Siberia and enhances the positive TCO trends over northwestern North America. However, the contribution of chemical processes to the zonally asymmetric TCO trends is relatively smaller than that of dynamical transport effects. Interpreting the zonally asymmetric TCO trends and their responsible factors would be helpful for accurately predicting the stratospheric ozone return date in the northern middle latitudes.

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Recent Decline in Extratropical Lower Stratospheric Ozone Attributed to Circulation Changes

Cited by 101 publications

References 52 publications

The Effects of a 1998 Observing System Change on MERRA‐2‐Based Ozone Profile Simulations

The Effects of a 1998 Observing System Change on MERRA‐2‐Based Ozone Profile Simulations

Possible Effects of Greenhouse Gases to Ozone Profiles and DNA Active UV-B Irradiance at Ground Level

Zonally asymmetric trends of winter total column ozone in the northern middle latitudes

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