ALBERT

Description: ABSTRACT Climate change affects mean and extreme temperature and precipitation, increasing the risk of related disasters. Assessing the performance of current models in simulating these aspects is therefore crucial to future projection and policymaking. Based on a large ensemble (LE; 30 members) of the Community Earth System Model (CESM-LE), this study seeks to answer the following two questions: (1) Are the simulated trends of mean and extreme temperature and precipitation over China consistent with observations? (2) What is the range of model uncertainty due to internal variability? The results show that CESM-LE can capture the trends of observed annul mean temperature and extremely low temperature days (ELD) over 16–26% of China, but has difficulty in reproducing the observed trends in extremely high temperature days (EHD). For precipitation, CESM-LE demonstrates similar capability in reproducing the observed trends in annual mean precipitation and extreme precipitation days (EPD). For consecutive dry days (CDD), the decreasing trends over part of northwestern China can be captured, but the increasing trends over northern China cannot be reproduced by CESM-LE. Regarding the uncertainty of the model resulting from natural internal variability, because all 30 ensemble members of CESM use the same model and external forcing, CESM-LE's spread (uncertainty) is mainly due to internal variability. Larger uncertainty in simulated trends is found over northern China and the Tibetan Plateau for annual mean temperature, over northeastern China and the Huang-Huai region for ELD, and over the Tibetan Plateau for EHD. The trends in annual mean precipitation show uniform uncertainty over nearly all of China, except for the northwest. Larger uncertainty trends appear over southern and northwestern China for EPD, and over the Tibetan Plateau and northern China for CDD.

Description: Long-term trends of aerosol concentrations and direct radiative forcings in East Asia have been investigated by adopting an online-coupled regional climate-chemistry-aerosol model (RIEMS-Chemaero) and the IPCC AR5 (the Intergovernmental Panel on Climate Change Fifth Assessment Report) emission inventory with the focus on eastern China. Model evaluation against surface observations of aerosol components demonstrates that the model can reproduce the spatial distribution and temporal variation of aerosol components generally well but tends to under-predict aerosol magnitudes especially for carbonaceous aerosols. Model comparison with aerosol optical depth (AOD) from both satellite retrieval and surface measurement shows that the model is capable of reproducing the distribution feature of AOD reasonably well but tends to under-predict magnitude. North of eastern China and the Sichuan basin are high concentration centres for near-surface anthropogenic aerosols. The domain averaged column burden of inorganic aerosol over East Asia increased from 1850 to 2010 with the peak in 1990 (18.7mg m -2 ), whereas that in eastern China peaked in 2010 (32.9 mg m -2 ). The burden of carbonaceous aerosol peaked in 1980 (5.2 mg m -2 ) in East Asia, but it peaked in 1990 (7.1 mg m -2 ) in eastern China and then decreased thereafter. Both inorganic and carbonaceous aerosol burdens showed little change during 1990-2000 due to effective emission control in China. AOD values over eastern China increased almost continuously from 1850 to 2010 with the Sichuan basin the high AOD centre. All-sky aerosol direct radiative forcing at the surface (ADRF SRF ) is negative over all of East Asia, while radiative forcing at the top of the atmosphere (ADRF TOA ) is negative over eastern China but positive over west China. Domain and annual mean ADRF SRF in East Asia peaked in 2000 (–11.9W m -2 ), but that in eastern China peaked in 2010 (–17.5 W m -2 ). Mean ADRF TOA became negative since 1970 and showed the strongest forcing in 1990 (– 2.9 W m -2 ) for East Asia and in 2010 (– 4.8 W m -2 ) for eastern China. Sensitivity simulation shows that anthropogenic emission change plays the dominant role in the variation of aerosol concentration and direct radiative forcing in this region. Keywords : aerosol concentration and burden, direct radiative forcing, interannual trend, East Asia, eastern China, model simulation (Published: 13 September 2013) Citation: Tellus B 2013, 65 , 20410, http://dx.doi.org/10.3402/tellusb.v65i0.20410 Access the supplementary material to this article – see Supplementary files under Article Tools online.

Description: A new high pressure device with a split cylinder was investigated on the basis of the belt-type apparatus. The belt-type die is subjected to excessive tangential tensile stress and the tungsten carbide cylinder is easily damaged in the running process. Taking into account the operating conditions and material properties of the tungsten carbide cylinder, it is divided into 6 blocks to eliminate the tangential tensile stress. We studied two forms of the split type: radial split and tangential split. Simulation results indicate that the split cylinder has more uniform stress distribution and smaller equivalent stress compared with the belt-type cylinder. The inner wall of the tangential split cylinder is in the situation that compressive stress is distributed in the axial, radial, and tangential directions. It is similar to the condition of hydrostatic pressure, and it is the best condition for tungsten carbide materials. The experimental results also verify that the tangential split die can bear the highest chamber pressure. Therefore, the tangential split structure can increase the pressure bearing capacity significantly.

Description: This paper focuses on an optimal quadrature error correction method for the dual-mass MEMS gyroscope, in order to reduce the long term bias drift. It is known that the coupling stiffness and demodulation error are important elements causing bias drift. The coupling stiffness in dual-mass structures is analyzed. The experiment proves that the left and right masses’ quadrature errors are different, and the quadrature correction system should be arranged independently. The process leading to quadrature error is proposed, and the Charge Injecting Correction (CIC), Quadrature Force Correction (QFC) and Coupling Stiffness Correction (CSC) methods are introduced. The correction objects of these three methods are the quadrature error signal, force and the coupling stiffness, respectively. The three methods are investigated through control theory analysis, model simulation and circuit experiments, and the results support the theoretical analysis. The bias stability results based on CIC, QFC and CSC are 48 °/h, 9.9 °/h and 3.7 °/h, respectively, and this value is 38 °/h before quadrature error correction. The CSC method is proved to be the better method for quadrature correction, and it improves the Angle Random Walking (ARW) value, increasing it from 0.66 °/√h to 0.21 °/√h. The CSC system general test results show that it works well across the full temperature range, and the bias stabilities of the six groups’ output data are 3.8 °/h, 3.6 °/h, 3.4 °/h, 3.1 °/h, 3.0 °/h and 4.2 °/h, respectively, which proves the system has excellent repeatability.

Description: Article Good thermoelectric materials are often complex compounds. Here, the authors reveal that elemental tellurium has a high thermoelectric figure of merit between 300 and 700 K when doped with As, with the potential advantages of easy preparation and relative isotropy. Nature Communications doi: 10.1038/ncomms10287 Authors: Siqi Lin, Wen Li, Zhiwei Chen, Jiawen Shen, Binghui Ge, Yanzhong Pei

Description: Despite the global expansion of water markets, their resilience has received little scholarly attention, even though they are vulnerable to external and internal disturbances. Since the 1990s, the water market has been actively promoted by China as an important institutional coordination mechanism for efficient water use. This article examines what contextual factors, in configurations, contribute to the resilience of water markets in China. We distinguish between resilient and factitious water markets as two outcome variables and distil four conditions from market environmentalism to explain the variance in their outcomes: ownership of water entitlements, market intermediaries, water pricing, and spot/forward trade categories. Using crisp-set qualitative comparative analysis (csQCA), we analyzed seven resilient and three factitious water markets in China. Our findings show that a water market’s framework is multidimensional and complex and that no necessary conditions contribute to resilience. Two sufficient solutions display the configurational complexity of water markets’ resilience. Path 1 includes strong intermediary, uncompetitive price, and forward water trade. Path 2 includes privatization of water entitlements, spot contracts, and competitive pricing. Weak intermediary together with forward water trade determines factitious water markets. The QCA results reveal that there exist multiple paths that a resilient water market can follow and develop. Therefore, policymakers must be cautious about pushing for water market indiscriminately, especially by over-privatization and unlimited investment in water banks.

Description: This study investigated the seasonal variation of nitrate concentration and its radiative forcing over East Asia by using an online-coupled regional climate model. Comparison with a series of in-situ observations from Acid Deposition Monitoring Network in East Asia (EANET) and China demonstrated a good skill of the model in reproducing the magnitude and seasonality of nitrate concentration across East Asia. It was found that nitrate concentration in Beijing and Tianjin exhibited the maximum in summer and the minimum in winter possibly due to stronger chemical oxidation and regional transport effect of larger emissions from the north China Plain in summer, whereas in most areas of East Asia, nitrate concentration was higher in winter and lower in summer, consistent with the seasonality of NOx emission. Surface nitrate concentration was higher over the lower reaches of the Yellow River, followed by the middle to lower reaches of the Yangtze River and portions of south China, and lower in Korean Peninsula and Japan. The annual mean surface nitrate concentration was predicted to be 2.9 μg·m−3 for East Asia and 8.5 μg·m−3 for east China. All-sky direct radiative forcing (DRF) due to nitrate at the top of the atmosphere (TOA) exhibited the largest forcing up to −7 W·m−2 over the lower reaches of the Yellow River, and lower forcing of ~−2 W·m−2 in the Korean Peninsula and Japan. Clear-sky DRF by nitrate reached the maximum in spring and the minimum in summer over both East Asia and east China, whereas DRF under all-sky condition showed its maximum in autumn, associated with seasonalities of nitrate column burden, relative humidity, and cloud effect. Annual mean all-sky DRFs at TOA were estimated to be −1.7 W·m−2 and −3.7 W·m−2 over East Asia and east China, respectively, significantly larger than global annual mean, suggesting the important role of nitrate aerosol in environment and climate change over East Asia.

Description: ABSTRACT Summer rainfall in north-central China, accounted for 70% of the annual rainfall, is sensitive to anomalies in the East Asian summer monsoon (EASM) and westerlies due to lying in the EASM marginal belt. Summer rainfall and the durations and frequency of dry spells were investigated using daily rainfall data from 332 weather stations, the European Centre for Medium-range Weather Forecasting (ECMWF) re-analysis data and Climate Research Unit (CRU) surface temperature data. The results demonstrate that summer rainfall exhibits an ‘early wetting later drying’ pattern with a weak increasing in June and a dramatic decreasing trend in July and August (JA). Decreased rainfall in JA is associated with prolonged dry spells; the frequency and durations of dry spells exceeding 7 days increase, especially for dry spells exceeding 15 days. This increase in dry spell duration is positively correlated with a northward shift in planetary waves expressed by the 5700-gpm isoline at 500 hPa and the westerly jet at 200 hPa, which lead north-central China to close to the left of jet entrance and a positive vorticity convergence region on the high level, it is helpful to downward movements and less rainfall. The northward shift in planetary waves is affected by boundary forcing. Dramatic increases in temperature over the Tibetan Plateau (TP) result in a large temperature gradient and thermal contrast between the TP and mid-high latitude, and likely strengthening and widening the South Asian High (SAH) pattern and pressure gradient. These conditions contribute to the northward shift in planetary waves and prolonging dry spells.