Winter precipitation over eastern China displays remarkable interannual variability,which has been suggested to be closely related to El Niño-Southern Oscillation(ENSO).This study finds that ENSO impacts on easte...Winter precipitation over eastern China displays remarkable interannual variability,which has been suggested to be closely related to El Niño-Southern Oscillation(ENSO).This study finds that ENSO impacts on eastern China precipitation patterns exhibit obvious differences in early(November-December)and late(January-February)winter.In early winter,precipitation anomalies associated with ENSO are characterized by a monopole spatial distribution over eastern China.In contrast,the precipitation anomaly pattern in late winter remarkably changes,manifesting as a dipole spatial distribution.The noteworthy change in precipitation responses from early to late winter can be largely attributed to the seasonally varying Kuroshio anticyclonic anomalies.During the early winter of El Niño years,anticyclonic circulation anomalies appear both over the Philippine Sea and Kuroshio region,enhancing water vapor transport to the entirety of eastern China,thus contributing to more precipitation there.During the late winter of El Niño years,the anticyclone over the Philippine Sea is further strengthened,while the one over the Kuroshio dissipates,which could result in differing water vapor transport between northern and southern parts of eastern China and thus a dipole precipitation distribution.Roughly the opposite anomalies of circulation and precipitation are displayed during La Niña winters.Further analysis suggests that the seasonally-varying Kuroshio anticyclonic anomalies are possibly related to the enhancement of ENSO-related tropical central-eastern Pacific convection from early to late winter.These results have important implications for the seasonal-tointerannual predictability of winter precipitation over eastern China.展开更多
The variation of the Asian winter monsoonal strength has seriously affected the climate and environmental conditions in the Asian monsoonal region, and even in marginal islands and the ocean in the East Asian region. ...The variation of the Asian winter monsoonal strength has seriously affected the climate and environmental conditions in the Asian monsoonal region, and even in marginal islands and the ocean in the East Asian region. However, relevant under-standing remains unclear due to the lack of suitable geological materials and effective proxies in the key study areas. Here, we present a grain-size record derived from the palaeo-aeolian sand dune in the southeastern Mu Us Desert, together with other proxies and OSL dating, which reflect a relatively detailed history of the winter monsoon and abrupt environmental events during the past 4.2 ka. Our grain-size standard deviation model indicated that 〉224 μm content can be considered as an indicator of the intensity of Asian winter monsoon, and it shows declined around 4.2–2.1 ka, enhanced but unstable in 2.1–0.9 ka, and obviously stronger since then. In addition, several typical climate events were also documented, forced by the periodic variation of winter monsoonal intensity. These include the cold intervals of 4.2, 2.8, 1.4 ka, and the Little Ice Age （LIA）, and relatively warm sub-phases around 3.0, 2.1, 1.8 ka, and the Medieval Warm Period （MWP）, which were roughly accordant with the records of the aeolian materials, peat, stalagmites, ice cores, and sea sediments in various latitudes of the Northern Hemisphere. Combined with the previous progresses of the Asian summer monsoon, we prelimi-narily confirmed a millennial-scale anti-correlation of Asian winter and summer monsoons in the Late Holocene epoch. This study suggests that the evolution of the palaeo-aeolian sand dune has the potential for comprehending the history of Asian monsoon across the desert regions of the modern Asian monsoonal margin in northern China.展开更多
Ammonia volatilized from aboveground parts of winter wheat was collected with an enclosure growth chamber and measured from jointing to maturing stage. The results showed that ammonia released from unfertilized plants...Ammonia volatilized from aboveground parts of winter wheat was collected with an enclosure growth chamber and measured from jointing to maturing stage. The results showed that ammonia released from unfertilized plants grown in high and low fertility soils remained at low rates of 2.3 and 0. 9μg NH3 40 plant-1 h-1 respectively at late filling stage. However, fertilized plants rapidly increased the rates to 43. 4 and 52. 2μg NH3, 40 plant-1 h-1 in the high and low fertility soils, respectively, at the same period. The released a-mount was different in different parts of plants. At filling stage, lower senescing stems and leaves volatilized more ammonia than upper parts, i. e. , ears and flag leaves that grew normally, with an average of 1. 4 and 0.7μg NH3 20 plant-1 h-1 respectively, strongly suggesting that it was the senile organs that released large amounts of ammonia. At the grain filling stage, shortage of water supply (drought stress) reduced ammonia volatilization. The average rate of ammonia released under water stress was 0. 9μg NH3 40 plant-1 h-1, but 1.2μg NH3 40 plant-1 h-1 with moderate water supply. Application of N together with P fertilizer resulted in a higher ammonia volatilization than N fertilization alone at the maturing stage. The average rate released was 135.3 μg NH3 40 plant-1 h-1 when 0.4 g N and 0.13 g P had been added to per kg soil, while 33. 7μg when 0. 4 g N added alone. Ammonia volatilization from plants was closely related with plant biomass and N uptake;P fertilization increased plant biomass and N uptake and therefore increased its release.展开更多
基金supported by the National Key R&D Program of China(2022YFF0801602).
文摘Winter precipitation over eastern China displays remarkable interannual variability,which has been suggested to be closely related to El Niño-Southern Oscillation(ENSO).This study finds that ENSO impacts on eastern China precipitation patterns exhibit obvious differences in early(November-December)and late(January-February)winter.In early winter,precipitation anomalies associated with ENSO are characterized by a monopole spatial distribution over eastern China.In contrast,the precipitation anomaly pattern in late winter remarkably changes,manifesting as a dipole spatial distribution.The noteworthy change in precipitation responses from early to late winter can be largely attributed to the seasonally varying Kuroshio anticyclonic anomalies.During the early winter of El Niño years,anticyclonic circulation anomalies appear both over the Philippine Sea and Kuroshio region,enhancing water vapor transport to the entirety of eastern China,thus contributing to more precipitation there.During the late winter of El Niño years,the anticyclone over the Philippine Sea is further strengthened,while the one over the Kuroshio dissipates,which could result in differing water vapor transport between northern and southern parts of eastern China and thus a dipole precipitation distribution.Roughly the opposite anomalies of circulation and precipitation are displayed during La Niña winters.Further analysis suggests that the seasonally-varying Kuroshio anticyclonic anomalies are possibly related to the enhancement of ENSO-related tropical central-eastern Pacific convection from early to late winter.These results have important implications for the seasonal-tointerannual predictability of winter precipitation over eastern China.
基金funded by the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZZD-EW-04-04)the National Natural Science Foundation of China (Nos., 41271215, 41501220)+1 种基金the China Postdoctoral Science Foundation (No. 2015M570861)the State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University (No. 2015-KF-13)
文摘The variation of the Asian winter monsoonal strength has seriously affected the climate and environmental conditions in the Asian monsoonal region, and even in marginal islands and the ocean in the East Asian region. However, relevant under-standing remains unclear due to the lack of suitable geological materials and effective proxies in the key study areas. Here, we present a grain-size record derived from the palaeo-aeolian sand dune in the southeastern Mu Us Desert, together with other proxies and OSL dating, which reflect a relatively detailed history of the winter monsoon and abrupt environmental events during the past 4.2 ka. Our grain-size standard deviation model indicated that 〉224 μm content can be considered as an indicator of the intensity of Asian winter monsoon, and it shows declined around 4.2–2.1 ka, enhanced but unstable in 2.1–0.9 ka, and obviously stronger since then. In addition, several typical climate events were also documented, forced by the periodic variation of winter monsoonal intensity. These include the cold intervals of 4.2, 2.8, 1.4 ka, and the Little Ice Age （LIA）, and relatively warm sub-phases around 3.0, 2.1, 1.8 ka, and the Medieval Warm Period （MWP）, which were roughly accordant with the records of the aeolian materials, peat, stalagmites, ice cores, and sea sediments in various latitudes of the Northern Hemisphere. Combined with the previous progresses of the Asian summer monsoon, we prelimi-narily confirmed a millennial-scale anti-correlation of Asian winter and summer monsoons in the Late Holocene epoch. This study suggests that the evolution of the palaeo-aeolian sand dune has the potential for comprehending the history of Asian monsoon across the desert regions of the modern Asian monsoonal margin in northern China.
基金This work was part of the projects of 40201028,30070429,49890330 and 30230230 supported by the National Natural Science Foundation of China(NFSC)the project of G1999011707 supported by National Key Basic Research Special Funds(NKBRSF).The authors would like to take the opportunity to thank the NFSC and the NKBRSF for their kindness of supporting these projects.
文摘Ammonia volatilized from aboveground parts of winter wheat was collected with an enclosure growth chamber and measured from jointing to maturing stage. The results showed that ammonia released from unfertilized plants grown in high and low fertility soils remained at low rates of 2.3 and 0. 9μg NH3 40 plant-1 h-1 respectively at late filling stage. However, fertilized plants rapidly increased the rates to 43. 4 and 52. 2μg NH3, 40 plant-1 h-1 in the high and low fertility soils, respectively, at the same period. The released a-mount was different in different parts of plants. At filling stage, lower senescing stems and leaves volatilized more ammonia than upper parts, i. e. , ears and flag leaves that grew normally, with an average of 1. 4 and 0.7μg NH3 20 plant-1 h-1 respectively, strongly suggesting that it was the senile organs that released large amounts of ammonia. At the grain filling stage, shortage of water supply (drought stress) reduced ammonia volatilization. The average rate of ammonia released under water stress was 0. 9μg NH3 40 plant-1 h-1, but 1.2μg NH3 40 plant-1 h-1 with moderate water supply. Application of N together with P fertilizer resulted in a higher ammonia volatilization than N fertilization alone at the maturing stage. The average rate released was 135.3 μg NH3 40 plant-1 h-1 when 0.4 g N and 0.13 g P had been added to per kg soil, while 33. 7μg when 0. 4 g N added alone. Ammonia volatilization from plants was closely related with plant biomass and N uptake;P fertilization increased plant biomass and N uptake and therefore increased its release.
