| 1. |
- Baresel, Christian, et al.
(författare)
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Direct GHG emissions from a pilot scale MBR-process treating municipal wastewater
- 2022
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Ingår i: Advances in Climate Change Research. - : Elsevier BV. - 1674-9278 .- 2524-1761. ; 13:1, s. 138-145
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate direct greenhouse gas emissions from Membrane Biological Reactor (MBR), measurements of nitrous oxide (N2O) and methane (CH4) were made at a pilot-scale MBR treating municipal wastewater Measurements were conducted during two campaigns with some changes in processes, i.e. introducing a pre-aeration tank in the second measurement, different distributions of aeration in the treatment line, not the same wastewater inflow rate, two types of ultrafiltration membrane. It was found that about 0.004% and 0.07% of the total ammonium loads were emitted as N2O, CH4 emissions were 0.026% and 0.12% of incoming TOC (0.008% and 0.04% of incoming COD) in 2014 and 2018. The obtained N2O emission values were relatively low.The study suggested that a high aeration at the beginning of the treatment line may result in significantly high emissions of both N2O and CH4. A significant change in aeration in the membrane ultrafiltration tank did not have the same impact. The MBR process is known for high quality effluent but have been questioned due to its higher carbon footprint due to energy consumption. This study gave a reference case about direct GHG emissions from MBR process and provide information for the further evaluation of MBR processes.
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| 2. |
- Chen, Z., et al.
(författare)
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Deep learning projects future warming-induced vegetation growth changes under SSP scenarios
- 2022
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Ingår i: Advances in Climate Change Research. - : Elsevier BV. - 1674-9278. ; 13:2, s. 251-257
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Tidskriftsartikel (refereegranskat)abstract
- Climate warming has been projected to enhance vegetation growth more strongly in higher latitudes than in lower latitudes, but different projections show distinct regional differences. By employing big data analysis (deep learning), we established gridded, global-scale, climate-driven vegetation growth models to project future changes in vegetation growth under SSP scenarios. We projected no substantial trends of vegetation growth change under the sustainable development scenario (SSP1-1.9) by the end of the 21st century. However, the increase of vegetation growth driven by climate warming shows distinct regional variability under the scenario representing high carbon emissions and severe warming (SSP5-8.5), especially in Northeast Asia where growth could increase by (6.00% ± 4.21%). This may be attributed to the high temperature sensitivities of the deciduous needleleaf forests and permanent wetlands in these regions. When the temperature sensitivity that is defined as permutation importance in deep learning is greater than 0.05, the increase in vegetation growth will be more prominent. In addition, an extreme temperature increase across grasslands, as well as changing land-use management in northern China may also influence the vegetation growth in the future. The results suggest that the sustainable development scenario can maintain stable vegetation growth, and it may be a reliable way to mitigate global warming due to potential climate feedbacks driven by vegetation changes in boreal regions. Deciduous needleleaf forests will be a centre of greening in the future, and it should become the focus of future vegetation dynamics modelling studies and projections. © 2022 The Authors
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| 3. |
- Kaiqiang, Deng, et al.
(författare)
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Shifting of summertime weather extremes in Western Europe during the last decade
- 2022
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Ingår i: Advances in Climate Change Research. - : Elsevier BV. - 1674-9278. ; 13:2, s. 218-227
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Tidskriftsartikel (refereegranskat)abstract
- Over the past decades, droughts and heatwaves frequently appeared in Western Europe (45°–65°N, 10°W–20°E) during boreal summer, causing huge impacts on human society and ecosystems. Although these extremes are projected to increase in both frequency and intensity under a warming climate, our knowledge of their interdecadal variations and causes is relatively limited. Here we show that the droughts and heatwaves in Western Europe have shifted in their trends in the last decade: for 1979–2012, wind speed and precipitation have both strengthened in Western Europe; for 2012–2020, however, Western Europe have experienced declined wind speed, decreased precipitation, and higher air temperature, leading to more frequent droughts and heatwaves there. Recent changes in the WE climate and extremes are related to the variations of the North Atlantic westerly jet stream. In 1979–2012 (2012–2020), the westerly jet stream shifted equatorward (poleward), which enhanced (reduced) transportation of water vapor fluxes from the North Atlantic Ocean to the European land areas, resulting in wetter (drier) surface in Western Europe. Further analysis suggests that phase changes in the Pacific Decadal Oscillation could have played a key role in regulating the position of the jet stream, providing important implications for decadal predictions of the Western Europe summertime climate and weather extremes. © 2022 The Authors
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| 4. |
- Zha, Jin Lin, et al.
(författare)
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Effects of Northern Hemisphere Annular Mode on terrestrial near-surface wind speed over eastern China from 1979 to 2017
- 2022
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Ingår i: Advances in Climate Change Research. - : Elsevier BV. - 1674-9278 .- 2524-1761. ; 13:6, s. 875-83
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale ocean‒atmosphere circulations (LOACs) have a pronounced effect on the near-surface wind speed (NSWS). In this study, we discussed the contributions of zonal and meridional flows to NSWS changes and identify the possible association between the Northern Hemisphere Annular Mode (NAM) and the NSWS changes over eastern China from 1979 to 2017. Results show that the reduction in NSWS over eastern China was mainly dominated by the weakening of the zonal wind component. NAM has a considerable effect on the NSWS over eastern China. When the NAM exhibits positive phases, the zonal-mean westerly weakens at low-to-mid-latitudes (10°–40°N). Meanwhile, descending flows prevail near 40°N, and ascending flows persist near 65°N in the troposphere. In the lower troposphere, there are northerly anomalies at low-to-mid-latitudes and southerly anomalies at mid-to-high latitudes (40°–70°N). The anomalous meridional flows transport heat from low to high latitudes and weaken the north‒south air temperature gradient. The decreased air temperature gradient over East Asia reduces the pressure gradient near the surface, decreasing NSWS in eastern China. NAM variations could dominate (32.0 ± 15.8)% of the changes in the annual mean NSWS. Nevertheless, the contribution of NAM to the interannual changes of the zonal component in NSWS could reach (45.0 ± 12.9)%.
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