In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Prec...In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation(CHNIP).During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ18O.The established local meteoric water line δD=7.42δ18O+1.38, based on the 95 obtained monthly composite samples, could be treated as isotopic input function across the region.The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions.The monthly δ18O values were characterized by a positive correlation with surface air temperature(δ18O(‰) =0.33 T(℃)-13.12).The amount effect visualized during summer period(δ18O(‰) =-0.04P(mm)-3.44) though not appeared at a whole yearly-scale.Spatial distributions of δ18O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China.The quan-titative simulation of δ18O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops.Furthermore, the raindrop suffered a re-evaporation during falling processes, and the precipitation vapor might have been mixed with a quantity of local recycled water vapor.Multiple linear regression equations and a δ18O-T relation have been gained by using meteorological parameters and δ18O data to evaluate physical controls on the long-term data.The established δ18O-T relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate.展开更多
The inhomogeneous and non-flat paleotopography in a depositional landform area profoundly controls the process of modem gully evolution and shapes the structure of a gully network. However, this controlling effect of ...The inhomogeneous and non-flat paleotopography in a depositional landform area profoundly controls the process of modem gully evolution and shapes the structure of a gully network. However, this controlling effect of paleotopography on modem gully evolution is mostly ignored because of the difficulties in paleotopography reconstruction. In this study, loess area in China is selected as case area for its typical depositional landform area and inhomogeneous and non-flat paleotopography during the Quaternary. The paleotopography underlying loess is considered while evaluating its controlling effects on the gully evolutionary process. On the basis of the geophysical prospecting, detailed geological information, and high-resolution digital elevation model, we reconstruct the pre-Quaternary paleotopographic surface in the case area. Comparative analysis is conducted to reveal the modern gully evolution in relation to the paleotopography. Results show that the concave area of the paleotopography acts as the basement of the high-order modern gully evolution in the hilly-gully area, although this concave area can be covered and buried by the loess depositional process during the Quaternary. A significant controlling effect of paleotopography on high-order modern gully evolution can be observed in a depositional landform with a hilly-gully underlying topography, whereas a relatively weak controlling effect exists in a flat underlying topograpnlcal area oecause of the strong horizontal shift effect of gully formation process. Several low-order modern gullies also exist and limit the controlling effect of paleotopography. These results reveal a controlled high-order modern gully evolutionary process and a rather dynamic low-order modem gully evolutionary process in the hilly-gully area. These results also help us understand the variations in different modern gully evolution in relation to paleotopography and the different management schemes for soil conservation and ecological restoration during the gully evolutionary process.展开更多
We theoretically propose a photonic flash based on a linearly coupled cavity system. Via driving the two side cavities by external fields, it forms a cyclic energy-level diagram and therefore the phase difference betw...We theoretically propose a photonic flash based on a linearly coupled cavity system. Via driving the two side cavities by external fields, it forms a cyclic energy-level diagram and therefore the phase difference between the driving fields acts as a controller of the steady state due to the quantum interference effect. In the optical trimer structure,we show that the perfect photonic flash can be realized in the situation of resonant driving. The perfect photonic flash scheme is furthermore generalized to multiple coupled cavity system, where the cavities with odd and even number turn bright and dark alternatively. Our proposal may be applied for designing the quantum neon and realizing a controllable photonic localization.展开更多
基金National Natural Science Foundation of China,No.40830636 No.40671034Foundation of Isotopes in Precipitation of Chinese Ecosystem Research Network
文摘In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation(CHNIP).During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ18O.The established local meteoric water line δD=7.42δ18O+1.38, based on the 95 obtained monthly composite samples, could be treated as isotopic input function across the region.The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions.The monthly δ18O values were characterized by a positive correlation with surface air temperature(δ18O(‰) =0.33 T(℃)-13.12).The amount effect visualized during summer period(δ18O(‰) =-0.04P(mm)-3.44) though not appeared at a whole yearly-scale.Spatial distributions of δ18O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China.The quan-titative simulation of δ18O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops.Furthermore, the raindrop suffered a re-evaporation during falling processes, and the precipitation vapor might have been mixed with a quantity of local recycled water vapor.Multiple linear regression equations and a δ18O-T relation have been gained by using meteorological parameters and δ18O data to evaluate physical controls on the long-term data.The established δ18O-T relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate.
基金supported by the National Natural Science Foundation of China(Grant Nos.41601411,41671389,41571383&41271438)AProject Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions-PAPD(Grant No.164320H101)
文摘The inhomogeneous and non-flat paleotopography in a depositional landform area profoundly controls the process of modem gully evolution and shapes the structure of a gully network. However, this controlling effect of paleotopography on modem gully evolution is mostly ignored because of the difficulties in paleotopography reconstruction. In this study, loess area in China is selected as case area for its typical depositional landform area and inhomogeneous and non-flat paleotopography during the Quaternary. The paleotopography underlying loess is considered while evaluating its controlling effects on the gully evolutionary process. On the basis of the geophysical prospecting, detailed geological information, and high-resolution digital elevation model, we reconstruct the pre-Quaternary paleotopographic surface in the case area. Comparative analysis is conducted to reveal the modern gully evolution in relation to the paleotopography. Results show that the concave area of the paleotopography acts as the basement of the high-order modern gully evolution in the hilly-gully area, although this concave area can be covered and buried by the loess depositional process during the Quaternary. A significant controlling effect of paleotopography on high-order modern gully evolution can be observed in a depositional landform with a hilly-gully underlying topography, whereas a relatively weak controlling effect exists in a flat underlying topograpnlcal area oecause of the strong horizontal shift effect of gully formation process. Several low-order modern gullies also exist and limit the controlling effect of paleotopography. These results reveal a controlled high-order modern gully evolutionary process and a rather dynamic low-order modem gully evolutionary process in the hilly-gully area. These results also help us understand the variations in different modern gully evolution in relation to paleotopography and the different management schemes for soil conservation and ecological restoration during the gully evolutionary process.
基金Supported by the National Natural Science Foundation of China(NSFC)under Grant Nos.11404021,11534002,11674049Jilin Province Science and Technology Development Plan under Grant No.20170520132JHFundamental Research Funds for the Central Universities under Grant Nos.2412016KJ015 and 2412016KJ004
文摘We theoretically propose a photonic flash based on a linearly coupled cavity system. Via driving the two side cavities by external fields, it forms a cyclic energy-level diagram and therefore the phase difference between the driving fields acts as a controller of the steady state due to the quantum interference effect. In the optical trimer structure,we show that the perfect photonic flash can be realized in the situation of resonant driving. The perfect photonic flash scheme is furthermore generalized to multiple coupled cavity system, where the cavities with odd and even number turn bright and dark alternatively. Our proposal may be applied for designing the quantum neon and realizing a controllable photonic localization.
