China's adjustment of climate change policies:what lessons can be learned from the US?

From the US New Energy Plan, personnel appointment, and diplomatic activities, etc., we can see that US is now on the way to returning to the negotiation table and undertaking the leadership in addressing climate change. What US has done puts tremendous challenges on China, which emits large amount of greenhouse gas into the atmosphere. However, different from US, China is undergoing rapid development, and huge energy consumption is unavoidable. China has to make a balance between developing economy and addressing climate change. This paper focuses on the US climate change policies and its greenhouse gas emissions, and its influences on China climate change policy. China greenhouse gas emissions and relative policies are also analyzed to see what situation China is in, and what challenges that China is facing. Consequently, combing China's local situation, we propose several solutions for China to address climate change, i.e. moving towards a low carbon economy, struggling for emitting more, enhancing China-US cooperation, and implementing different climate change policies based on local situation. Meanwhile, the achievements that China has made are also introduced.

浅谈高三物理习题讲评课的作用

进入高三阶段,教师如何更好地有针对性地指导学生有效地提高复习的质量,就涉及到习题如何讲评才能起到更好的功效,本文就如何上好习题讲评课及更好地指导学生复习做一下探讨。

The Impacts of the Interannual Variability of Vegetation on the Interannual Variability of Global Evapotranspiration: A Modeling Study

The impact of the interannual variability (IAV) of vegetation on the IAV of evapotranspiration is investigated with the Community Land Model (CLM3.0) and modified Dynamic Global Vegetation Model (DGVM). Two sets of 50-year off-line simulations are used in this study. The simulations begin with the same initial surface-water and heat states and are driven by the same atmospheric forcing data. The vegetation exhibits interannual variability in one simulation but not in the other simulation. However, the climatological means for the vegetation are the same. The IAV of the 50-year annual total evapotranspiration and its three partitions (ground evaporation, canopy evaporation, and transpiration) are analyzed. The global distribution of the evapotranspiration IAV and the statistics of evapotranspiration and its components in different ecosystems show that the IAV of ground evaporation is generally large in areas dominated by grass and deciduous trees, whereas the IAV of canopy evaporation and transpiration is large in areas dominated by bare soil and shrubs. For ground evaporation, canopy evaporation, and transpiration, the changes in IAV are larger than the mean state over most grasslands and shrublands. The study of two sites with the same IAV in the leaf area index (LAI) shows that the component with the smaller contribution to the total evapotranspiration is more sensitive to the IAV of vegetation. The IAV of the three components of evapotranspiration increases with the IAV of the fractional coverage (FC) and the LAI. The ground evaporation IAV shows the greatest increase, whereas the canopy evaporation shows the smallest increase.

The Seasonal Variations of the Climatic Circulation of the Black Sea along the Axis of Divergence Zone

The spatial position, seasonal variability and intensity of the main flow and the cyclonic circulation of the Black Sea waters along the axis of the divergence were identified. Corresponding calculations were done with using of the dynamic method and based on the climate data set of temperature and salinity for the surface and intermediate layers of the Black Sea. The important role of spring floods on the rivers of the northern-western Black Sea in the development of the water circulation features was shown because this river＇s water and main Black Sea current interact with the periphery of the western and eastern cyclonic circulation. This process is dominated at the western part sea surface cyclone： in spring and at eastern, in summer and autumn. The flow rate and nature of seasonal migration cyclonic centers were estimated. The results of research are based on a relatively large scale （40＇ latitude and 60＇ longitude） averaging and we have identified the main area of water divergence. Small, localized areas of convergence and divergence of flow that are presented in the Black Sea were not included into the scope of our research.

经济转型和增长

经济学家们正在对新古典增长模型作一些改进,以研究经济体和技术进步率在横截面(空间)数据上的不同。这些模型描述了经济体的变化状态,这些变化状态包括不同经济体收敛于稳态路径和变化中出现的各种相同或不同的形式。这篇论文详细阐述了对这些变化进行建模的机制和如何在计量上将这些变化测算出来。我们提出了关于衡量收敛的一个新的回归检验方法,推导出了它的渐进性质,给出它的有限样本性质的模拟结果。在对美国区域数据,经合组织数据以及宾夕法尼亚大学世界表(Penn World Table da-ta),运用一系列经验方法研究的基础上,我们得出了单个经济体和经济组织的变化曲线。