Abstract Chinese air pollution has increased in this century along with the rapid socioeconomic development and resulting anthropogenic emissions. While recent emission control measures have shown encouraging re sults...Abstract Chinese air pollution has increased in this century along with the rapid socioeconomic development and resulting anthropogenic emissions. While recent emission control measures have shown encouraging re sults and have reduced the levels of sulfur dioxide and primary aerosols, the concentrations of other air pollutants continue to grow, particularly secondary pollutants in cluding ozone and secondary aerosols. Meanwhile, a va riety of intentional and unintentional socioeconomic events have temporarily changed the pace, and even the signs, of growth of air pollution. These events include the short-term emission restrictions imposed during the Sino-African Summit, the Beijing Olympics and Para lympics, the Shanghai World Exposition （Shanghai Expo）, the Guangzhou Asian Olympics, and the Shenzhen Uni versiade, as well as the unintentional emission reductions associated with the recent economic recession and the annual Chinese New Year. This paper presents a brief overview of trends and temporary perturbations of Chi nese air pollution since 2000, summarizing studies on anthropogenic emission inventories, atmospheric meas urements, and inverse modeling. It concludes with rec ommendations for future research.展开更多
Understanding precipitation variability and trends is very important for sustainable water management. In this paper, we used 65 years (1951-2016) long- term precipitation data to evaluate the precipitation variabilit...Understanding precipitation variability and trends is very important for sustainable water management. In this paper, we used 65 years (1951-2016) long- term precipitation data to evaluate the precipitation variability and trends in Quelimane, and their relation to El Ni<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">ñ</span></span>o Southern Oscillation (ENSO). The analysis includes annual, inter-annual inter-decadal variations, Mann-Kendall trend test, and drought frequency. The study also evaluated the relationship between Oceanic Ni<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">ñ</span></span>o Index (ONI) and precipitation patterns during ENSO positive, normal and negative phases. The results show two distinct seasons of precipitation in Quelimane, the wet season extending between December and April and the dry season extending from May to November. ENSO was found to influence the inter-annual variations of precipitation during the wet season, with warm ENSO (El Ni<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">ñ</span></span>o) and cold (La Ni<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">ñ</span></span>a) events tending to reduce and increase the precipitation amounts, respectively. Decreasing trends in inter-annual variations of precipitation and increase of drought frequency and severity are highlighted in this study. Both decreasing trend of inter-annual variations and increasing of drought frequency and severity have intensified after the 1970s climate shift. These intensifications seem to be associated with the strengthening of ENSO after the 1970s climate shift. The results of the present study may be useful for the design of the climate change adaptation plans in central Mozambique.展开更多
In this study, we focused on describing the trends of Extreme Precipitation Indices (EPI) in Senegal and analyzing the significant links between their variability and key climatic factors such as the El Niño-Sout...In this study, we focused on describing the trends of Extreme Precipitation Indices (EPI) in Senegal and analyzing the significant links between their variability and key climatic factors such as the El Niño-Southern Oscillation Index (ONI), the Land-Ocean Temperature Index (LOTI), and the Land Surface Temperature Index (LST). Based on a century of daily rainfall data from various Senegalese stations, this study utilized twelve (12) EPIs calculated according to the definitions of the Expert Team on Climate Change Detection and Indices (ETCCDI). To analyze the temporal variation characteristics of extreme precipitation, the Mann-Kendall (MK) test was employed to perform a uniformity test on the precipitation data series. A dependence method through differentiation was used to remove data trends and observe correlations between the climate change indices ONI, LOTI, LST, and EPIs. An approach based on lagged correlations between the ONI index and the EPIs was applied to evaluate the predictability of extreme precipitation patterns in Senegal. Trend analysis indicates a significant decrease in total precipitation and frequency and intensity indices in most stations, while duration indices show no clear trend. Regarding their interannual variability, the analysis shows negative correlations between ONI and total precipitation, consistent with the known influence of ENSO on Sahel precipitation. Correlations with LOTI and LST indices, on the other hand, suggest that the Clausius-Clapeyron theory does not hold at Senegal’s latitudes, but that adjacent Atlantic ocean warming influence is crucial in modulating extreme precipitation patterns. Finally, on the predictability of extreme precipitation, the study shows a significant signal up to three months in advance with ENSO for 58% of the EPIs and up to two months in advance for 90% of the EPIs.展开更多
This paper summarizes research related to the 2012 record the NEWS （NASA （National Aeronautics and Space Administration） drought in the central United States conducted by members of Energy and Water cycle Study） W...This paper summarizes research related to the 2012 record the NEWS （NASA （National Aeronautics and Space Administration） drought in the central United States conducted by members of Energy and Water cycle Study） Working Group. Past drought patterns were analyzed for signal coherency with latest drought and the contribution of long-term trends in the Great Plains low-level jet, an important regional circulation feature of the spring rainy season in the Great Plains. Long-term changes in the seasonal transition from rainy spring into dry summer were also examined. Potential external forcing from radiative processes, soil-air interactions, and ocean teleconnections were assessed as contributors to the intensity of the drought. The atmospheric Rossby wave activity was found to be a potential source of predictability for the onset of drought. A probabilistic model was introduced and evaluated for its performance in predicting drought recovery in the Great Plains.展开更多
The change of sea surface temperature（SST） in the southern Indian Ocean（SIO） during the recent six decades has been analyzed based on oceanic reanalysis and model, as well as atmospheric data. The results show tha...The change of sea surface temperature（SST） in the southern Indian Ocean（SIO） during the recent six decades has been analyzed based on oceanic reanalysis and model, as well as atmospheric data. The results show that a thermal regime shift in SIO during the 1960 s, which is not caught enough attentions, has been of equal magnitude to the linear warming since 1970. Empirical Orthogonal Function（EOF） analyses reveal that a thermal shift is combined with atmospheric changes such as the weakening of westerly during the period of 1960–1967. Inner dynamic connections can be defined that when the westerly winds turn weak, the anticyclonic wind circulation between westerly winds and the trade winds decreases, which further reduces the SST to a negative peak in this period. It is noted that the shifts in the 1960 s are also evident for Southern Hemisphere. For example, subtropical high and the entire westerly winds belt at high latitudes both change dramatically in the 1960 s. This large-scaled process maybe link to the change of southern annular mode（SAM）.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41005078 and 41175127)
文摘Abstract Chinese air pollution has increased in this century along with the rapid socioeconomic development and resulting anthropogenic emissions. While recent emission control measures have shown encouraging re sults and have reduced the levels of sulfur dioxide and primary aerosols, the concentrations of other air pollutants continue to grow, particularly secondary pollutants in cluding ozone and secondary aerosols. Meanwhile, a va riety of intentional and unintentional socioeconomic events have temporarily changed the pace, and even the signs, of growth of air pollution. These events include the short-term emission restrictions imposed during the Sino-African Summit, the Beijing Olympics and Para lympics, the Shanghai World Exposition （Shanghai Expo）, the Guangzhou Asian Olympics, and the Shenzhen Uni versiade, as well as the unintentional emission reductions associated with the recent economic recession and the annual Chinese New Year. This paper presents a brief overview of trends and temporary perturbations of Chi nese air pollution since 2000, summarizing studies on anthropogenic emission inventories, atmospheric meas urements, and inverse modeling. It concludes with rec ommendations for future research.
文摘Understanding precipitation variability and trends is very important for sustainable water management. In this paper, we used 65 years (1951-2016) long- term precipitation data to evaluate the precipitation variability and trends in Quelimane, and their relation to El Ni<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">ñ</span></span>o Southern Oscillation (ENSO). The analysis includes annual, inter-annual inter-decadal variations, Mann-Kendall trend test, and drought frequency. The study also evaluated the relationship between Oceanic Ni<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">ñ</span></span>o Index (ONI) and precipitation patterns during ENSO positive, normal and negative phases. The results show two distinct seasons of precipitation in Quelimane, the wet season extending between December and April and the dry season extending from May to November. ENSO was found to influence the inter-annual variations of precipitation during the wet season, with warm ENSO (El Ni<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">ñ</span></span>o) and cold (La Ni<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#F7F7F7;">ñ</span></span>a) events tending to reduce and increase the precipitation amounts, respectively. Decreasing trends in inter-annual variations of precipitation and increase of drought frequency and severity are highlighted in this study. Both decreasing trend of inter-annual variations and increasing of drought frequency and severity have intensified after the 1970s climate shift. These intensifications seem to be associated with the strengthening of ENSO after the 1970s climate shift. The results of the present study may be useful for the design of the climate change adaptation plans in central Mozambique.
文摘In this study, we focused on describing the trends of Extreme Precipitation Indices (EPI) in Senegal and analyzing the significant links between their variability and key climatic factors such as the El Niño-Southern Oscillation Index (ONI), the Land-Ocean Temperature Index (LOTI), and the Land Surface Temperature Index (LST). Based on a century of daily rainfall data from various Senegalese stations, this study utilized twelve (12) EPIs calculated according to the definitions of the Expert Team on Climate Change Detection and Indices (ETCCDI). To analyze the temporal variation characteristics of extreme precipitation, the Mann-Kendall (MK) test was employed to perform a uniformity test on the precipitation data series. A dependence method through differentiation was used to remove data trends and observe correlations between the climate change indices ONI, LOTI, LST, and EPIs. An approach based on lagged correlations between the ONI index and the EPIs was applied to evaluate the predictability of extreme precipitation patterns in Senegal. Trend analysis indicates a significant decrease in total precipitation and frequency and intensity indices in most stations, while duration indices show no clear trend. Regarding their interannual variability, the analysis shows negative correlations between ONI and total precipitation, consistent with the known influence of ENSO on Sahel precipitation. Correlations with LOTI and LST indices, on the other hand, suggest that the Clausius-Clapeyron theory does not hold at Senegal’s latitudes, but that adjacent Atlantic ocean warming influence is crucial in modulating extreme precipitation patterns. Finally, on the predictability of extreme precipitation, the study shows a significant signal up to three months in advance with ENSO for 58% of the EPIs and up to two months in advance for 90% of the EPIs.
文摘This paper summarizes research related to the 2012 record the NEWS （NASA （National Aeronautics and Space Administration） drought in the central United States conducted by members of Energy and Water cycle Study） Working Group. Past drought patterns were analyzed for signal coherency with latest drought and the contribution of long-term trends in the Great Plains low-level jet, an important regional circulation feature of the spring rainy season in the Great Plains. Long-term changes in the seasonal transition from rainy spring into dry summer were also examined. Potential external forcing from radiative processes, soil-air interactions, and ocean teleconnections were assessed as contributors to the intensity of the drought. The atmospheric Rossby wave activity was found to be a potential source of predictability for the onset of drought. A probabilistic model was introduced and evaluated for its performance in predicting drought recovery in the Great Plains.
基金The National Natural Science Foundation of China for Distinguished Young Scholars and Innovative Research Groups under contract Nos 41525019 and 41521005the Project of the State Oceanic Administration of China for Global Climate Change under contract No.GASI-IPOVAI-02the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘The change of sea surface temperature（SST） in the southern Indian Ocean（SIO） during the recent six decades has been analyzed based on oceanic reanalysis and model, as well as atmospheric data. The results show that a thermal regime shift in SIO during the 1960 s, which is not caught enough attentions, has been of equal magnitude to the linear warming since 1970. Empirical Orthogonal Function（EOF） analyses reveal that a thermal shift is combined with atmospheric changes such as the weakening of westerly during the period of 1960–1967. Inner dynamic connections can be defined that when the westerly winds turn weak, the anticyclonic wind circulation between westerly winds and the trade winds decreases, which further reduces the SST to a negative peak in this period. It is noted that the shifts in the 1960 s are also evident for Southern Hemisphere. For example, subtropical high and the entire westerly winds belt at high latitudes both change dramatically in the 1960 s. This large-scaled process maybe link to the change of southern annular mode（SAM）.
