TY - JOUR

T1 - The evolving role of weather types on rainfall chemistry under large reductions in pollutant emissions

AU - Tso, C.-H.M.

AU - Monteith, D.

AU - Scott, T.

AU - Watson, H.

AU - Dodd, B.

AU - Pereira, M.G.

AU - Henrys, P.

AU - Hollaway, M.

AU - Rennie, S.

AU - Lowther, A.

AU - Watkins, J.

AU - Killick, R.

AU - Blair, G.

PY - 2022/4/15

Y1 - 2022/4/15

N2 - Long-term change and shorter-term variability in the atmospheric deposition of pollutants and marine salts can have major effects on the biogeochemistry and ecology of soils and surface water ecosystems. In the 1980s, at the time of peak acid deposition in the UK, deposition loads were highly dependent on prevailing weather types, and it was postulated that future pollution recovery trajectories would be partly dependent on any climate change-driven shifts in weather systems. Following three decades of substantial acidic emission reductions, we used monitoring data collected between 1992 and 2015 from four UK Environmental Change Network (ECN) sites in contrasting parts of Great Britain to examine the trends in precipitation chemistry in relation to prevailing weather conditions. Weather systems were classified on the basis of Lamb weather type (LWT) groupings, while emissions inventories and clustering of air mass trajectories were used to interpret the observed patterns. Concentrations of ions showed clear differences between cyclonic-westerly-dominated periods and others, reflecting higher marine and lower anthropogenic contributions in Atlantic air masses. Westerlies were associated with higher rainfall, higher sea salt concentrations, and lower pollutant concentrations at all sites, while air mass paths exerted additional controls. Westerlies therefore have continued to favour higher sea salt fluxes, whereas emission reductions are increasingly leading to positive correlations between westerlies and pollutant fluxes. Our results also suggest a shift from the influence of anthropogenic emissions to natural emissions (e.g., sea salt) and climate forcing as they are transported under relatively cleaner conditions to the UK. Westerlies have been relatively frequent over the ECN monitoring period, but longer-term cyclicity in these weather types suggests that current contributions to precipitation may not be sustained over coming years. © 2022 The Authors

AB - Long-term change and shorter-term variability in the atmospheric deposition of pollutants and marine salts can have major effects on the biogeochemistry and ecology of soils and surface water ecosystems. In the 1980s, at the time of peak acid deposition in the UK, deposition loads were highly dependent on prevailing weather types, and it was postulated that future pollution recovery trajectories would be partly dependent on any climate change-driven shifts in weather systems. Following three decades of substantial acidic emission reductions, we used monitoring data collected between 1992 and 2015 from four UK Environmental Change Network (ECN) sites in contrasting parts of Great Britain to examine the trends in precipitation chemistry in relation to prevailing weather conditions. Weather systems were classified on the basis of Lamb weather type (LWT) groupings, while emissions inventories and clustering of air mass trajectories were used to interpret the observed patterns. Concentrations of ions showed clear differences between cyclonic-westerly-dominated periods and others, reflecting higher marine and lower anthropogenic contributions in Atlantic air masses. Westerlies were associated with higher rainfall, higher sea salt concentrations, and lower pollutant concentrations at all sites, while air mass paths exerted additional controls. Westerlies therefore have continued to favour higher sea salt fluxes, whereas emission reductions are increasingly leading to positive correlations between westerlies and pollutant fluxes. Our results also suggest a shift from the influence of anthropogenic emissions to natural emissions (e.g., sea salt) and climate forcing as they are transported under relatively cleaner conditions to the UK. Westerlies have been relatively frequent over the ECN monitoring period, but longer-term cyclicity in these weather types suggests that current contributions to precipitation may not be sustained over coming years. © 2022 The Authors

KW - Climatic effects

KW - Deposition

KW - Lamb weather types

KW - Major ions

KW - Rainfall chemistry

KW - Air pollution

KW - Atmospheric chemistry

KW - Binary alloys

KW - Climate change

KW - Ecosystems

KW - Marine pollution

KW - Meteorological problems

KW - Rain

KW - Surface waters

KW - Air mass

KW - Emission reduction

KW - Environmental change networks

KW - Rainfall chemistries

KW - Sea salts

KW - Weather systems

KW - Weather types

KW - Emission control

U2 - 10.1016/j.envpol.2022.118905

DO - 10.1016/j.envpol.2022.118905

M3 - Journal article

VL - 299

JO - Environmental Pollution

JF - Environmental Pollution

SN - 0269-7491

M1 - 118905

ER -