Summer monsoons （South Asian monsoon, South China Sea monsoon and Subtropical monsoon） are prominent features of summertime climate over southern China. Dif- ferent monsoons carry different inflow moisture into Chin...Summer monsoons （South Asian monsoon, South China Sea monsoon and Subtropical monsoon） are prominent features of summertime climate over southern China. Dif- ferent monsoons carry different inflow moisture into China and control the temporal and spatial distributions of precipitation. Analyses of meteorological data, particularly wind, tempera- ture and pressure anomalies are traditional methods of characterizing moisture sources and transport patterns. Here, we try to utilize the evidence from stable isotopes signatures to trace summer monsoons over southern China. Based on seven CHNIP （Chinese Network of Iso- topes in Precipitation） observatory stations located in southern China, monthly composite precipitation samples have been collected and analyzed for the composition of δ^18O during July, 2005. The results indicated that the spatial distributions of δ^18O in precipitation could properly portray the moisture sources together with their transport pathways. Moreover, the amount effect, altitude effect, temperature effect and the correlation between δ^18O vs. relative humidity were discussed.展开更多
Monsoon circulation is an important carrier of water vapor transport, and it impacts the precipitation of the monsoonal regions through the constraints and controls of large-scale water vapor transport and distributio...Monsoon circulation is an important carrier of water vapor transport, and it impacts the precipitation of the monsoonal regions through the constraints and controls of large-scale water vapor transport and distributions as well as the water vapor balance. An overall research on stable Hydrogen and Oxygen isotopes in precipitation over Eastern Monsoon China could benefit a comprehensive understanding of the monsoonal precipitation mechanism. Seventeen field stations of the Chinese Network of Isotopes in Precipitation (CHNIP) have been selected to collect monthly composite precipitation samples during the years 2005―2006. Components of δ D and δ 18O have been analyzed to achieve the spatiotemporal distributions. The established Local Meteoric Water Line δ D=7.46δ 18O+0.90 based on the 274 obtained monthly samples could be treated as isotope input functions across the region, due to basically reflecting the specific regional meteorological conditions over Eastern Monsoon China. The δ-value depleted from coastal to inner area. In Southern China and Northeastern China there were typical periodic patterns of δ18O. Different dominant affecting metrological factors have been raised with different regions. From south to north, the temperature effect of δ18O enhanced, while the amount effect changed from existing at an all-year-scale in Southern China to being only remarkable during the main rainy seasons in North China and Northeastern China. Main geographical controls varied from altitude in Southern China and North China to latitude in Northeastern China. Furthermore, δ18O had an implication of advance and retreat of the monsoon as well as rainfall belt transfer. δ 18O was also a tracer for the movement path of typhoon and tropical storms.展开更多
Evapotranspiration(ET) and its controlling mechanism over the desert riparian forests in arid regions are the important scientific basis for the water resources managements of the lower reaches of the inland rivers of...Evapotranspiration(ET) and its controlling mechanism over the desert riparian forests in arid regions are the important scientific basis for the water resources managements of the lower reaches of the inland rivers of China. Nearly three years of continuous measurements of surface ET, soil water content at different depths and groundwater table over a typical Tamarix spp. stand and a typical Populus euphratica stand were conducted in the lower reach of the Tarim River. The ET seasonal trends in the growing season were controlled by plant phenology, and ET in non-growing season was weak. The diurnal variations of ET resulting from the comprehensive effects of all atmospheric factors were significantly related with reference ET. The spatial pattern of ET was determined by vegetation LAI, more vegetation coverage, more ET amount. Groundwater is the water source of surface ET, and the soil water in shallow layers hardly took part in the water exchange in the groundwatersoil-plant-air system. The temporal processes of ET over the Tamarix stand and the Populus stand were similar, but the water consumption of the well-grown Populus euphratica was higher than that of the well-grown Tamarix spp. Further analysis indicates that plant transpiration accounts for most of the surface ET, with soil evaporation weak and negligible; groundwater table is a crucial factor influencing ET over the desert riparian forests, groundwater influences the processes and amounts of ET by controlling the growth and spatial distribution of desert riparian forests; quantifying the water stress of desert riparian forests using groundwater table is more appropriate, rather than soil water content. Based on the understanding of ET and water movements in the groundwater-soil-plant-air system, a generalized framework expressing the water cycling and its key controlling mechanism in the lower reaches of the inland rivers of China is described, and a simple model to estimate water requirements of the desert riparian forests is presented.展开更多
Global climate change has significant impacts on agricultural production. Future climate change will bring important influences to the food security. The CERES-Wheat model was used to simulate the winter wheat growing...Global climate change has significant impacts on agricultural production. Future climate change will bring important influences to the food security. The CERES-Wheat model was used to simulate the winter wheat growing process and production in Panzhuang Irriga- tion District （PID） during 2011-2040 under B2 climate scenario based on the Special Report on Emissions Scenarios （SRES） assumptions with the result of RCMs （Regional Climate Models） projections by PRECIS （Providing Regional Climates for Impacts Studies） system introduced to China from the Hadley Centre for Climate Prediction and Research. The CERES-Wheat model was calibrated and validated with independent field-measured growth data in 2002-2003 and 2007-2008 growing season under current climatic conditions at Yucheng Comprehensive Experimental Station （YCES）, Chinese Academy of Sciences （CAS） The results show that a significant impact of climate change on crop growth and yield was noted in the PID study area. Average temperature at Yucheng Station rose by 0.86℃ for 1961-2008 in general. Under the B2 climate scenario, average temperature rose by 0.55℃ for 2011-2040 compared with the baseline period （1998-2008）, which drastically shortened the growth period of winter-wheat. However, as the temperature keep increasing after 2030, the top-weight and yield of the winter wheat will turn to decrease. The simulated evapotran- spiration shows an increasing trend, although it is not very significant, during 2011-2040. Water use efficiency will increase during 2011-2031, but decrease during 2031-2040. The results indicate that climate change enhances agricultural production in the short-term, whereas continuous increase in temperature limits crop production in the long-term.展开更多
基金National Natural Science Foundation of China, No. 40671034 Foundation of Isotopes in Precipitation of Chinese Ecosystem Research Network The authors would like to acknowledge Synthesis Center of Chinese Ecosystem Research Center and National Meteorological Information Center, China Meteorological Administration for providing the meteorological data. We also thank Yang Jinrong and Yuan Jingjing for sample analysis. At the same time, sincerely appreciation is given to all the observatory field stations for the collection of precipitation samples and a tour of their facilities.
文摘Summer monsoons （South Asian monsoon, South China Sea monsoon and Subtropical monsoon） are prominent features of summertime climate over southern China. Dif- ferent monsoons carry different inflow moisture into China and control the temporal and spatial distributions of precipitation. Analyses of meteorological data, particularly wind, tempera- ture and pressure anomalies are traditional methods of characterizing moisture sources and transport patterns. Here, we try to utilize the evidence from stable isotopes signatures to trace summer monsoons over southern China. Based on seven CHNIP （Chinese Network of Iso- topes in Precipitation） observatory stations located in southern China, monthly composite precipitation samples have been collected and analyzed for the composition of δ^18O during July, 2005. The results indicated that the spatial distributions of δ^18O in precipitation could properly portray the moisture sources together with their transport pathways. Moreover, the amount effect, altitude effect, temperature effect and the correlation between δ^18O vs. relative humidity were discussed.
基金supported by the Na-tional Natural Science Foundation of China (Grant Nos.40830636 and 40671034)Foundation of Isotopes in Precipitation of Chinese Ecosystem Research Network
文摘Monsoon circulation is an important carrier of water vapor transport, and it impacts the precipitation of the monsoonal regions through the constraints and controls of large-scale water vapor transport and distributions as well as the water vapor balance. An overall research on stable Hydrogen and Oxygen isotopes in precipitation over Eastern Monsoon China could benefit a comprehensive understanding of the monsoonal precipitation mechanism. Seventeen field stations of the Chinese Network of Isotopes in Precipitation (CHNIP) have been selected to collect monthly composite precipitation samples during the years 2005―2006. Components of δ D and δ 18O have been analyzed to achieve the spatiotemporal distributions. The established Local Meteoric Water Line δ D=7.46δ 18O+0.90 based on the 274 obtained monthly samples could be treated as isotope input functions across the region, due to basically reflecting the specific regional meteorological conditions over Eastern Monsoon China. The δ-value depleted from coastal to inner area. In Southern China and Northeastern China there were typical periodic patterns of δ18O. Different dominant affecting metrological factors have been raised with different regions. From south to north, the temperature effect of δ18O enhanced, while the amount effect changed from existing at an all-year-scale in Southern China to being only remarkable during the main rainy seasons in North China and Northeastern China. Main geographical controls varied from altitude in Southern China and North China to latitude in Northeastern China. Furthermore, δ18O had an implication of advance and retreat of the monsoon as well as rainfall belt transfer. δ 18O was also a tracer for the movement path of typhoon and tropical storms.
基金supported by the National Natural Science Foundation of China(Grant No.41271050)the National Basic Research Program of China(Grant No.2010CB951002)
文摘Evapotranspiration(ET) and its controlling mechanism over the desert riparian forests in arid regions are the important scientific basis for the water resources managements of the lower reaches of the inland rivers of China. Nearly three years of continuous measurements of surface ET, soil water content at different depths and groundwater table over a typical Tamarix spp. stand and a typical Populus euphratica stand were conducted in the lower reach of the Tarim River. The ET seasonal trends in the growing season were controlled by plant phenology, and ET in non-growing season was weak. The diurnal variations of ET resulting from the comprehensive effects of all atmospheric factors were significantly related with reference ET. The spatial pattern of ET was determined by vegetation LAI, more vegetation coverage, more ET amount. Groundwater is the water source of surface ET, and the soil water in shallow layers hardly took part in the water exchange in the groundwatersoil-plant-air system. The temporal processes of ET over the Tamarix stand and the Populus stand were similar, but the water consumption of the well-grown Populus euphratica was higher than that of the well-grown Tamarix spp. Further analysis indicates that plant transpiration accounts for most of the surface ET, with soil evaporation weak and negligible; groundwater table is a crucial factor influencing ET over the desert riparian forests, groundwater influences the processes and amounts of ET by controlling the growth and spatial distribution of desert riparian forests; quantifying the water stress of desert riparian forests using groundwater table is more appropriate, rather than soil water content. Based on the understanding of ET and water movements in the groundwater-soil-plant-air system, a generalized framework expressing the water cycling and its key controlling mechanism in the lower reaches of the inland rivers of China is described, and a simple model to estimate water requirements of the desert riparian forests is presented.
基金National High-tech Program of China, No.2007AA10Z223 National Basic Research Program of China,No.2005CB121103
文摘Global climate change has significant impacts on agricultural production. Future climate change will bring important influences to the food security. The CERES-Wheat model was used to simulate the winter wheat growing process and production in Panzhuang Irriga- tion District （PID） during 2011-2040 under B2 climate scenario based on the Special Report on Emissions Scenarios （SRES） assumptions with the result of RCMs （Regional Climate Models） projections by PRECIS （Providing Regional Climates for Impacts Studies） system introduced to China from the Hadley Centre for Climate Prediction and Research. The CERES-Wheat model was calibrated and validated with independent field-measured growth data in 2002-2003 and 2007-2008 growing season under current climatic conditions at Yucheng Comprehensive Experimental Station （YCES）, Chinese Academy of Sciences （CAS） The results show that a significant impact of climate change on crop growth and yield was noted in the PID study area. Average temperature at Yucheng Station rose by 0.86℃ for 1961-2008 in general. Under the B2 climate scenario, average temperature rose by 0.55℃ for 2011-2040 compared with the baseline period （1998-2008）, which drastically shortened the growth period of winter-wheat. However, as the temperature keep increasing after 2030, the top-weight and yield of the winter wheat will turn to decrease. The simulated evapotran- spiration shows an increasing trend, although it is not very significant, during 2011-2040. Water use efficiency will increase during 2011-2031, but decrease during 2031-2040. The results indicate that climate change enhances agricultural production in the short-term, whereas continuous increase in temperature limits crop production in the long-term.
