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...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)%.展开更多
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 extrem...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.展开更多
基金supported by the National Natural Science Foundation of China(42071022)the start-up fund provided by Southern University of Science and Technology(29/Y01296122)+3 种基金Highlight Project on Water Security and Global Change of Southern University of Science and Technology(G02296302)supported by Evaluación y atribución de la variabilidad de la velocidad media y las rachas máximas de viento:causas del fenómeno stilling(RTI2018-095749-A-100)Cambios observados,proyecciones futuras eíndices de la velocidad del viento y sus extremos en la Comunidad Valenciana(AICO/2021/023)the Spanish National Research Centre Interdisciplinary Thematic Platform PTI-CLIMA。
基金National Key Research and Development Program of China(2018YFA0606004)Natural Science Foundation of China(42005023,41875178,41865001)+1 种基金Swedish Formas(2019-00509 and 2017-01408)VR(2021-02163 and 2019-03954).
文摘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)%.
基金supports from the National Natural Science Foundation of China(42088101)the Swedish Research Council(VR:2017-03780,2019-03954)+4 种基金the Swedish FORMAS(2018-02858),the Ramon Y Cajal Fellowship(RYC-2017-22830)the Spanish Ministry of Science,Innovation and Universities(RTI2018-095749-A-I00)China Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies(2020B1212060025)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0606)the Swedish MERGE and BECC,and the China Jiangsu Collaborative Innovation Center for Climate Change.
文摘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.
