The intensification and shift of the annual North Atlantic Oscillation in a global warming scenario simulation

Hu, Zeng‐Zhen; Wu, Zhaohua

doi:10.1111/j.1600-0870.2004.00050.x

Cited by 57 publications

(37 citation statements)

References 42 publications

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“…The significant increase in mean NAOI value is consistent with previous climate change and MFR simulations (e.g. Karpechko, 2010;Gillet and Fyfe, 2013;Pausata et al, 2015), as is the eastward shift of the variability pattern (Hu and Wu, 2004;Kuzmina et al, 2005;Dong et al, 2011;Pausata et al, 2015) which has itself been linked to a more positive NAO (Peterson et al, 2003). Even though the differences in the location of the NACs across different climate models can be very large (Davini and Cagnazzo, 2014), the eastward shift of the two poles under anthropogenic climate change scenarios therefore appears to be a robust result.…”

Section: Discussionsupporting

confidence: 77%

“…A number of modelling studies suggest a future positive shift in the NAO as part of anthropogenic climate change (e.g. Hu and Wu, 2004;Kuzmina et al, 2005;Karpechko, 2010;Gillet and Fyfe, 2013). The changing weather patterns associated with a more positive NAO will likely affect PM concentrations across Europe, with potentially major impacts on public health (Pausata et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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The impact of future atmospheric circulation changes over the Euro-Atlantic sector on urban PM<sub>2.5</sub> concentrations

Messori

Wees

Pausata

et al. 2018

Tellus B: Chemical and Physical Meteorology

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Air quality management is strongly driven by legislative aspects related to the exceedance of air quality limit values. Here, we use the Norwegian Climate Centre's Earth System Model to assess the impact of a future scenario of maximum feasible aerosol emission abatement and increasing greenhouse gases (RCP4.5) on urban PM 2.5 concentrations in Europe. Daily PM 2.5 concentrations are assessed using a novel downscaling method which allows us to compute exceedances of current and planned air quality thresholds. For the latter, we assume that future ambitious emission reductions are likely to be accompanied by stricter air quality thresholds. The changes in PM 2.5 concentrations are discussed in the context of the large-scale atmospheric changes observed relative to the present-day climate. Our results show a more positive North Atlantic Oscillation mean state in the future, combined with a large eastward shift of both North Atlantic sea-level pressure centres of action. This is associated with more frequent mid-latitude blocking and a northward shift of the jet stream. These changes favour higher than expected anthropogenic urban PM 2.5 concentrations in Southern Europe, while they have the opposite effect on the northern half of the continent. In the future scenario, PM concentrations in substantial parts of Southern Europe are found to exceed the World Health Organisation Air Quality Guideline daily limit of 25 lg/m 3 on 25 to over 50 days per year, and annual guidelines of 10 mg/m 3 on more than 80% of the 30 years analysed in our study. We conclude that alterations in atmospheric circulation in the future, induced by stringent maximum feasible air pollution mitigation as well as GHG emissions, will negatively influence the effectiveness of these emission abatements over large parts of Europe. This has important implications for future air quality policies.

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Section: Discussionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

The impact of future atmospheric circulation changes over the Euro-Atlantic sector on urban PM<sub>2.5</sub> concentrations

Messori

Wees

Pausata

et al. 2018

Tellus B: Chemical and Physical Meteorology

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“…Peterson et al (2003 have suggested that this shift is simply a consequence of the trend towards a more positive NAO index in the last two decades of the 20th century. Hu and Wu (2004), using both data and a coupled general circulation model, have also shown that a shift of both SLP centres of action took place in the second half of the last century, which will likely continue in the future. Our study confirms that this shift also occurs under a global warming scenario.…”

Section: Discussionmentioning

confidence: 99%

“…Gillett and Fyfe, 2013;Karpechko, 2010;Stephenson et al, 2006;Kuzmina, 2005;Hu and Wu, 2004); however, the driving mechanisms behind these shifts are still under debate. Hori et al (2007) have shown that NAO variability does not change substantially in the SRES-A1B scenarios compared to the 20th century, and conclude that the trend in the NAO index is the result of an anthropogenic trend in the basic mean state, rather than being due to changes in NAO variability.…”

Section: Discussionmentioning

confidence: 99%

The role of aerosol in altering North Atlantic atmospheric circulation in winter and its impact on air quality

et al. 2015

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Abstract. Numerical model scenarios of future climate depict a global increase in temperatures and changing precipitation patterns, primarily driven by increasing greenhouse gas (GHG) concentrations. Aerosol particles also play an important role by altering the Earth's radiation budget and consequently surface temperature. Here, we use the general circulation aerosol model ECHAM5-HAM, coupled to a mixed layer ocean model, to investigate the impacts of future air pollution mitigation strategies in Europe on winter atmospheric circulation over the North Atlantic. We analyse the extreme case of a maximum feasible end-of-pipe reduction of aerosols in the near future (2030), in combination with increasing GHG concentrations. Our results show a more positive North Atlantic Oscillation (NAO) mean state by 2030, together with a significant eastward shift of the southern centre of action of sea-level pressure (SLP). Moreover, we show a significantly increased blocking frequency over the western Mediterranean.By separating the impacts of aerosols and GHGs, our study suggests that future aerosol abatement may be the primary driver of both the eastward shift in the southern SLP centre of action and the increased blocking frequency over the western Mediterranean. These concomitant modifications of the atmospheric circulation over the Euro-Atlantic sector lead to more stagnant weather conditions that favour air pollutant accumulation, especially in the western Mediterranean sector. Changes in atmospheric circulation should therefore be included in future air pollution mitigation assessments. The indicator-based evaluation of atmospheric circulation changes presented in this work will allow an objective firstorder assessment of the role of changes in wintertime circulation on future air quality in other climate model simulations.

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“…Studies have shown that the Mediterranean region is projected to have less cyclonic and more anticyclonic activity until the end of the 21st century (Hueging et al, 2013;Kjellström et al, 2011). The Icelandic Low and Azores High are projected to be shifted northeastward in the global warming scenario revealed by GCM studies (e.g., Hu & Wu, 2004;Reyers et al 2015), and the intensification of the pressure gradient between the main centers (i.e., the Azores High and Icelandic Low) over the North Atlantic have been identified (Hu & Wu, 2004;Knippertz et al, 2000). The northward displacement of zonal winds could lead to more frequent windstorms over the North Sea (Hueging et al, 2013;Pinto et al, 2007).…”

Section: Projected Changes In Large-scale Pressure Conditions Over Eumentioning

confidence: 99%

Wind Over the Adriatic Region in CORDEX Climate Change Scenarios

et al. 2019

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Near‐surface winds over the Adriatic region are examined under present‐day and future climate conditions for two greenhouse gas scenarios (Representative Concentration Pathway 4.5 and Representative Concentration Pathway 8.5) with an ensemble of high‐resolution (0.11°) Coordinated Regional Climate Downscaling Experiment (CORDEX) simulations. The influence of particular combinations of regional climate models and global climate models and emission scenarios on the future changes in the near‐surface wind field has been explored in more detail. Starting with the seasonal climate change signal in large‐scale flow over the entire CORDEX domain, we focus on regional daily wind fields over the Adriatic domain and subdaily features of well‐known regional winds (Bora and Sirocco winds). The analysis reveals the strong sensitivity of the climate change signal in the simulated wind flow to (i) the choice of the global climate model that provides the boundary conditions and (ii) the analyzed locations across the Adriatic region. The results of the 21st‐century projections indicate that the changes in synoptic activity have an impact on the wind field at the (sub)daily time scale. We found a reduction in the number of Bora events and increase in the number of Sirocco events in northern Adriatic during the winter season, with an increase in pressure in the middle of the 21st century. Overall, the mean wind speed during Bora and Sirocco events is reduced, except for Bora in northern Adriatic. For the summer season, we found a large increase in the number of thermally induced flows, which is probably caused by the weakening of the Azores High.

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The intensification and shift of the annual North Atlantic Oscillation in a global warming scenario simulation

Cited by 57 publications

References 42 publications

The impact of future atmospheric circulation changes over the Euro-Atlantic sector on urban PM<sub>2.5</sub> concentrations

The impact of future atmospheric circulation changes over the Euro-Atlantic sector on urban PM<sub>2.5</sub> concentrations

The role of aerosol in altering North Atlantic atmospheric circulation in winter and its impact on air quality

Wind Over the Adriatic Region in CORDEX Climate Change Scenarios

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