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| 1 | Seasonal patterns and environmental control of ecosystem respiration in subtropical and temperate forests in China显示文摘Continuous measurement of carbon dioxide exchange using the eddy covariance (EC) technique was made at two ChinaFLUX forest sites including the young subtropical Pinus plantation (Qianyanzhou) and old temperate broad-leaved Korean pine mixed forest (Changbai Mountains) as part of the ChinaFLUX network. Seasonal patterns and environmental control of ecosystem respiration in the subtropical and temperate forests were evaluated by the often-used multiplicative model and Q10 model as a function of temperature and soil water content. The resuits suggested that ( i ) temperature was found to be a dominant factor in the ecosystem respiration, and most of the temporal variability of ecosystem respiration was explained by temperature. However, in the drought-stressed ecosystem, soil water content controlled the temporal variability of ecosystem respiration other than temperature effects, and soil water content became a dominat factor when severe drought affected the ecosystem respiration; (ii) the regression models analysis revealed that in the drier soil, ecosystem respiration was more sensitive to soil moisture than was expressed by the often-used multiplicative model. It was possible to accurately estimate the seasonal variation of ecosystem respiration based on the Q10 model; and (iii)annual ecosystem respiration derived from the often-used multiplicative model was 1209 g C m-2and 1303 g C m-2, and was consistently a little higher than the Q10 model estimates of 1197 g C m-2 and 1268 g C m-2 for Qianyanzhou and Changbai Mountains, respectively. | YU Guirui, WEN Xuefa, LI Qingkang, ZHANG Leiming, REN Chuanyou, LIU Yunfen & GUAN Dexin Chinese Ecosystem Research Network Synthesis Research Center, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China Graduate School of the Chinese Academy of Sciences, Beijing 100039, China | 2005 | Science China Earth Sciences2005，48，z1： | 13 |
| 2 | Photosynthesis-transpiration coupling model at canopy scale in terrestrial ecosystem显示文摘At the hypothesis of big leaf, an ecosystem photosynthesis-transpiration coupling cycle model was established by the scaled SMPT-SB model from single leaf to canopy, and model parameterization methods were discussed. Through simulating the canopy light distribution, canopy internal conductance to CO2 can be scaled from single leaf to canopy by integrating to canopy using the relationship between single internal conductance and photosynthetic photon flux density. Using the data observed by eddy covariance method from the Changbai Mountains site of ChinaFLUX, the application of the model at the canopy scale was examined. Under no water stress, the simulated net ecosystem photosynthesis rate fitted with the observed data very well, the slope and R2 of the line regression equation of the observed and simulated values were 0.7977 and 0.8892, respectively (n = 752), and average absolute error was 3.78 μmol CO2 m-2s-1; the slope, R2 and average absolute error of transpiration rate were 0.7314, 0.4355 and 1.60mmol H2O m-2 s-1, respectively (n = 752). The relationship between canopy photosynthesis,transpiration and external environmental conditions was discussed by treating the canopy as a whole and neglecting the comprehensive feedback mechanism within canopy, and it was noted that the precipitation course affected the transpiration rate simulation badly. Compared to the models based on eco-physiological processes, the SMPT-SB model was simple and easy to be used. And it can be used as a basic carbon and water coupling model of soil-plant-atmosphere continuum. | REN Chuanyou, YU Guirui, WANG Qiufeng & GUAN Dexin Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Shenyang Agricultural University, Shenyang 110161, China Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China Graduate School of the Chinese Academy of Sciences, Beijing 100039, China | 2005 | Science China Earth Sciences2005，48，z1： | 5 |
| 3 | A long-range forecasting model for the thermosphere based on the intelligent optimized particle filtering显示文摘The uncertainties associated with the variations in the thermosphere are responsible for the inaccurate prediction of the orbit decay of low Earth orbiting space objects due to the drag force.Accurate forecasting of the thermosphere is urgently required to avoid satellite collisions,which is a potential threat to the rapid growth of spacecraft applications.However,owing to the imperfections in the physics-based forecast model,the long-range forecast of the thermosphere is still primitive even if the accurate prediction of the external forcing is achieved.In this study,we constructed a novel methodology to forecast the thermosphere for tens of days by specifying the uncertain parameters in a physics-based model using an intelligent optimized particle filtering algorithm.A comparison of the results suggested that this method has the capability of providing a more reliable forecast with more than 30-days leading time for the thermospheric mass density than the existing ones under both weak and severe disturbed conditions,if solar and geomagnetic forcing is known.Moreover,the accurate estimation of the state of thermosphere based on this technique would further contribute to the understanding of the temporal and spatial evolution of the upper atmosphere. | Dexin REN Jiuhou LEI | 2022 | Science China Earth Sciences2022，65，1： | 1 |
| 4 | Simultaneous coproduction of hydrogen and methane from sugary wastewater by an “ACSTR H –UASB Met ” system显示文摘 | Bing Wang Yongfeng Li Dexin Wang Ruina Liu Zhigang Wei Nanqi Ren | 2013 | International Journal of Hydrogen Energy2013，，19： | 1 |
| 5 | Prediction of the thermospheric and ionospheric responses to the 21 June 2020 annular solar eclipse显示文摘On 21 June 2020,an annular solar eclipse will traverse the low latitudes from Africa to Southeast Asia.The highest latitude of the maximum eclipse obscuration is approximately 30°.This low-latitude solar eclipse provides a unique and unprecedented opportunity to explore the impact of the eclipse on the low-latitude ionosphere–thermosphere(I–T)system,especially in the equatorial ionization anomaly region.In this study,we describe a quantitative prediction of the impact of this upcoming solar eclipse on the I–T system by using Thermosphere–Ionosphere–Electrodynamics General Circulation Model simulations.A prominent total electron content(TEC)enhancement of around 2 TEC units occurs in the equatorial ionization anomaly region even when this region is still in the shadow of the eclipse.This TEC enhancement lasts for nearly 4.5 hours,long after the solar eclipse has ended.Further model control simulations indicate that the TEC increase is mainly caused by the eclipse-induced transequatorial plasma transport associated with northward neutral wind perturbations,which result from eclipse-induced pressure gradient changes.The results illustrate that the effect of the solar eclipse on the I–T system is not transient and linear but should be considered a dynamically and energetically coupled system. | Tong Dang JiuHou Lei WenBin Wang MaoDong Yan DeXin Ren FuQing Huang | 2020 | Earth and Planetary Physics2020，4，3： | 1 |
| 6 | Vibration control on shells through theoretical and numerical analysis显示文摘 | Dexin Ren Jie Hong Lulu Chen | 2014 | International English Education Research2014，，6： | 0 |
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