The NCEP/NCAR reanalysis, Japan Meteorological Agency(JMA) tropical cyclone tracks and intensive surface observations are used to diagnose the features of moisture transport of tropical storm Bilis(No. 0604), which is...The NCEP/NCAR reanalysis, Japan Meteorological Agency(JMA) tropical cyclone tracks and intensive surface observations are used to diagnose the features of moisture transport of tropical storm Bilis(No. 0604), which is simulated by the WRF(weather research and forecasting) mesoscale numerical model. It is shown that the Bilis was linked with the moisture channel in the lower latitudes after its landing. Meanwhile, the cross-equatorial flows over 80°-100°E and Somali were active and brought abundant water vapor into the tropical storm, facilitating the maintenance of the landing storm with intensified heavy rainfall along its path. The simulation suggested that the decreased water vapor from lower latitudes prevents the maintenance of Bilis and the development of rainfall. While the cross-equatorial flows over 80°-100°E and Somali were in favor of keeping the cyclonic circulation over land. If the moisture supply fro m the Somali jet stream was reduced, the strength and area of heavy rainfall in tropical cyclone would be remarkably weakened. Consequently, the decreased water vapor from lower latitudes can remarkably suppress the deep convection in tropical storm, then Bilis was damped without the persistent energy support and the rainfall was diminished accordingly.展开更多
Aims Studying legacy effects(i.e.the indirect effect that persists for a period after casual factors cease)can provide novel insights into the role of ecological drivers.Leaf lifespan is among the key traits with mult...Aims Studying legacy effects(i.e.the indirect effect that persists for a period after casual factors cease)can provide novel insights into the role of ecological drivers.Leaf lifespan is among the key traits with multi-level functions.It is clear about the direct effects of water and nitrogen(N)amendment on leaf lifespan,but it remains unclear about their legacy effects on leaf lifespan and the associated mechanisms.Methods We performed a five-year field experiment with supplemental water and N,and quantified the legacy effects of field water and N addi-tion on the leaf lifespan,length and growth rate of four dominant species,Agropyron cristatum,Cleistogenes squarrosa,Leymus chin-ensis and Stipa grandis in a temperate steppe.Important Findings Across all the species,the legacies of water and N addition increased their leaf length and growth rate directly but decreased their leaf lifespan through direct and indirect pathways.Leaf lifes-pan was positively linked with leaf length but negatively associ-ated to leaf growth rate.the legacy effect of water addition on leaf lifespan was greater than that of N addition.Field N addition induced soil acidification and eutrophication,as well as altered soil microbes,but only eutrophication had negative legacy effects on leaf lifespan.these findings provide substantial evidence that rainfall and N amendment have negative legacy effects on leaf lifespan,and also highlight that multiple mechanisms or pathways determine legacy effects.Additionally,our results suggest that field water and N manipulations may influence the other leaf traits and functions.展开更多
For urban land development, some or all natural land uses （primarily pervious） are converted into impervious areas which lead to increases of runoff volume and peak discharge. Most of the developed countries require...For urban land development, some or all natural land uses （primarily pervious） are converted into impervious areas which lead to increases of runoff volume and peak discharge. Most of the developed countries require a zero increase in peak discharge for any land development, and the policy has been implemented for several decades. The policy of zero increase in peak discharge can be considered as historical and early stage for the low impact development （LID） and sustainable development, which is to maintain natural hydrological conditions by storing a part or all of additional runoff due to the development on site. The paper will discuss the policy, the policy implementation for individual projects and their impact on regional hydrology. The design rainfalls for sizing LID facilities that are determined in 206 weather stations in USA are smaller than design rainfalls for sizing detention basins.The zero-increase policy links to financial responsibility and sustainability for construction of urban stormwater infrastructures and for reducing urban flooding. The policy was compared with current practices of urban development in China to shine the light for solving urban stormwater problems. The connections and differences among LID practices, the zero-increase policy, and the flood control infrastructure were discussed. We promote and advocate the zero-increase policy on peak discharge for comprehensive stormwater management in China in addition to LID.展开更多
基金Major Program of the Natural Science Researches for Colleges and Universities in Jiangsu Province(14KJA170004)'333'Project of Jiangsu ProvinceNational Natural Science Foundation of China(41575081,41175061)
文摘The NCEP/NCAR reanalysis, Japan Meteorological Agency(JMA) tropical cyclone tracks and intensive surface observations are used to diagnose the features of moisture transport of tropical storm Bilis(No. 0604), which is simulated by the WRF(weather research and forecasting) mesoscale numerical model. It is shown that the Bilis was linked with the moisture channel in the lower latitudes after its landing. Meanwhile, the cross-equatorial flows over 80°-100°E and Somali were active and brought abundant water vapor into the tropical storm, facilitating the maintenance of the landing storm with intensified heavy rainfall along its path. The simulation suggested that the decreased water vapor from lower latitudes prevents the maintenance of Bilis and the development of rainfall. While the cross-equatorial flows over 80°-100°E and Somali were in favor of keeping the cyclonic circulation over land. If the moisture supply fro m the Somali jet stream was reduced, the strength and area of heavy rainfall in tropical cyclone would be remarkably weakened. Consequently, the decreased water vapor from lower latitudes can remarkably suppress the deep convection in tropical storm, then Bilis was damped without the persistent energy support and the rainfall was diminished accordingly.
基金This work was funded by the Ministry of Science and Technology of China(2015BAC02B05)National Natural Science Foundation of China(31570538).
文摘Aims Studying legacy effects(i.e.the indirect effect that persists for a period after casual factors cease)can provide novel insights into the role of ecological drivers.Leaf lifespan is among the key traits with multi-level functions.It is clear about the direct effects of water and nitrogen(N)amendment on leaf lifespan,but it remains unclear about their legacy effects on leaf lifespan and the associated mechanisms.Methods We performed a five-year field experiment with supplemental water and N,and quantified the legacy effects of field water and N addi-tion on the leaf lifespan,length and growth rate of four dominant species,Agropyron cristatum,Cleistogenes squarrosa,Leymus chin-ensis and Stipa grandis in a temperate steppe.Important Findings Across all the species,the legacies of water and N addition increased their leaf length and growth rate directly but decreased their leaf lifespan through direct and indirect pathways.Leaf lifes-pan was positively linked with leaf length but negatively associ-ated to leaf growth rate.the legacy effect of water addition on leaf lifespan was greater than that of N addition.Field N addition induced soil acidification and eutrophication,as well as altered soil microbes,but only eutrophication had negative legacy effects on leaf lifespan.these findings provide substantial evidence that rainfall and N amendment have negative legacy effects on leaf lifespan,and also highlight that multiple mechanisms or pathways determine legacy effects.Additionally,our results suggest that field water and N manipulations may influence the other leaf traits and functions.
基金The study is partially supported by the National Natural Science Foundation of China （Grant No. 51478026）.
文摘For urban land development, some or all natural land uses （primarily pervious） are converted into impervious areas which lead to increases of runoff volume and peak discharge. Most of the developed countries require a zero increase in peak discharge for any land development, and the policy has been implemented for several decades. The policy of zero increase in peak discharge can be considered as historical and early stage for the low impact development （LID） and sustainable development, which is to maintain natural hydrological conditions by storing a part or all of additional runoff due to the development on site. The paper will discuss the policy, the policy implementation for individual projects and their impact on regional hydrology. The design rainfalls for sizing LID facilities that are determined in 206 weather stations in USA are smaller than design rainfalls for sizing detention basins.The zero-increase policy links to financial responsibility and sustainability for construction of urban stormwater infrastructures and for reducing urban flooding. The policy was compared with current practices of urban development in China to shine the light for solving urban stormwater problems. The connections and differences among LID practices, the zero-increase policy, and the flood control infrastructure were discussed. We promote and advocate the zero-increase policy on peak discharge for comprehensive stormwater management in China in addition to LID.
