不同数据源下毛乌素沙地风况及输沙势特征

风是干旱、半干旱区风蚀风积地貌发育的动力基础,我们通常使用风速资料探讨区域风况,但选取不同的风速资料研究同一区域风况时结果存在差异。以毛乌素沙地为例,分别选取中国气象数据网（CMDC）的日最大风速及风向与美国国家气候数据中心（NCDC）的日8个定时观测风速及风向,对比分析起沙风特征。结果表明：（1）毛乌素沙地平均起沙风速相差较小,但起沙风频率明显在CMDC数据源中较高;（2）毛乌素沙地年起沙风向均以WNW、W和NW为主,但年起沙风次风向、不同区域夏季和秋季起沙风次风向组成均在CMDC数据源中较复杂,且起沙风主次风向频率均在CMDC数据源中较高;（3）毛乌素沙地整体均属于低风能环境,中等风向变率,锐双峰或宽单峰风况,但以最大风速计算的年输沙势约是以定时观测风速计算结果的3.3倍。基于两套数据源定量对比分析毛乌素沙地风况及输沙势,这对区域风况研究是一种新的尝试,以期提高对不同数据源提供的风速差异的认识,为今后不同区域的起沙风分析提供一定的参考。     

The comparison of two severe Hwangsa (Asian dust) cases of spring and winter in Seoul, Korea

This study investigated meteorological, physical, and chemical characteristics of 2 severe Hwangsa (Asian dust, maximum average of PM₁₀ above 1000 μg m^?3) observed in Seoul, the capital city of Korea, during 30～31^st May, 2008 (DSS2008) and 25～26^th December, 2009 (DSS2009). DSS2008 and DSS2009 had a same source region and route. However, they have different meteorological conditions. DSS2009 had a shorter travel time from the source region to Korea and shorter duration time in Korea than DSS2008 due to a strong winter Siberian anticyclone. One of DSS2008 sample was affected by not only Asian dust but also a long-range transported haze due to consecutive influx after low pressure passed while DSS2009 sample collected only dust aerosol. For both cases, the mass concentration of coarse particles (PM_10-1) increased by 3～14 times compared to that during non Asian dust period, however, that of fine particles (PM₁) increased only in DSS2008. For DSS2008 water-soluble ion balance between anions and cations in fine mode was close to 1:1 while cations were higher than anions in coarse mode. NH₄ ⁺ and Ca²⁺ were found to be the main contributing factors for the neutralization. Cl^? loss was observed about 60% indicating an active interaction of Na⁺ with pollutants. Reconstruction of chemical compositions showed relatively high concentrations of secondary pollutants (NH₄NO₃ and (NH₄)₂SO₄), CaCO₃, and Ca(NO₃)₂ compared to that during non Asian dust period. DSS2009 exhibited the typical characteristics of Asian dust having a high concentration of Ca²⁺ with higher equivalent concentration of cations than anions in all size bins. Cl^? loss was hardly observed. The secondary pollutants were lower than that of non Asian dust cases. The result of reconstruction of ionic components indicated the CaCO₃ derived from soil particle, CaSO₄, and Ca (NO₃)₂ were dominant in DSS2009.     

广东低温阴雨的低频振荡及环流特征

为了做好广东2—3月低温阴雨的中期与延伸期预报,该文分析了1953—2011年广州低温阴雨年景变化与广东低温阴雨年景变化的关系,并采用小波分析、相关分析等方法探讨了12月—次年4月广州逐日气温的低频振荡及与低温阴雨的关系。结果表明:广州低温阴雨的年景变化与广东年景一致的相同率达94.9%(56/59)。轻度低温阴雨年份,12月—次年4月广州逐日气温主要存在8.0~18.3 d显著周期,而中等及严重年份主要存在10.1~28.4 d及30~89.6 d的振荡。2—3月长低温阴雨主要与18 d以上的周期振荡有关,尤其与45 d以上的季节内振荡强度变化密切相关。利用典型个例的合成分析,建立了长低温阴雨30~64 d季节内振荡的天气概念模型,它们反映了长低温阴雨回暖—降温—开始—维持—结束的大气环流演变特征,其中乌拉尔山—贝加尔湖以西的阻塞高压可作为广东出现长低温阴雨的500 hPa前兆信号。     

水泥复合偏高岭土稳定粉砂土力学特性试验研究

使用低成本高硅铝矿物掺合料可在提升水泥土工程性能的同时降低水泥用量。通过开展系列抗压强度试验研究了水泥偏高岭土掺比、水/水泥偏高岭土比、凝胶总掺量和养护龄期对水泥复合偏高岭土稳定粉砂土抗压强度的影响规律,归纳了水泥复合偏高岭土稳定粉砂土的强度经验公式。结果表明：将水泥和偏高岭土按质量比5:1混合用于粉砂土稳定时可获得最佳强度提升,节约1/6水泥消耗,且该掺比关系不因凝胶总掺量变化而改变;水泥复合偏高岭土稳定粉砂土抗压强度随水/水泥偏高岭土比增加近似线性降低,随凝胶总掺量增加线性提升,随龄期发展而提高,其28天强度增加趋势仍未趋缓;总结归纳了四个关于强度影响因素的经验预测公式。该研究成果可为水泥偏高岭土用于复合稳定工程软弱土提供理论参考。     

A study on carbon dioxide emissions from bituminous coal in Korea

Consumption of primary energy in Korea increased 5.25 % per year over a 10 years span starting in 1990. Korea ranked 8th in primary energy consumption in 2011; coal consumption increased 35 % from 87,827 million tons in 2006–119,321 tons in 2010. Heavy energy-consuming countries consistently conduct research to develop an emission factor of Tier 2 level, reflecting the characteristics of the fuel that they use. To calculate the emission factor of bituminous coal for fuel, this study developed emission factor and calculated emission amount by implementing fuel analysis on bituminous coal consumed in Korea between 2007 and 2009. CO₂ emission factor calculated by fuel analysis method is 95,315 kg/TJ, which is 0.75 % higher than the default value suggested by IPCC. The emission amount calculated by using the CO₂ emission factor in this study is 231.881 million tons, which has a difference of 1.739 million tons compared to the IPCC default value.     

简论城市边缘区研究

本文主要论述了城市边缘区的基本概念,城市边缘区研究产生背景、研究的主要内容以及研究动向,并认为我国城市边缘区的研究具有宽阔的发展前景和深远的理论和实践意义。     

天然矿物自然铝的研究进展

综述了国内外自然铝的发现与研究史;自然铝的物理性质和颗粒形态、元素组成及含量、晶体结构参数等特征;自然铝的成因模式。自然铝主要见于老的火山和热液矿石中,或现代和中-新生代的海底活动构造带（如转换断层、中央海隆以及弧后扩张中心）的海洋沉积物中,有地幔碳热还原、海底热液内生和陆地表生置换等3种成因模式。     

汛期我国主要雨季进程成因及预测应用进展

汛期内我国中东部地区的雨季是东亚夏季风推进过程中的重要产物,主要包括华南前汛期、梅雨、华北雨季和华西秋雨等,各地雨季决定了我国中东部地区汛期的旱涝布局和旱涝演变,是我国汛期预测和服务的重点。该文回顾了4个雨季特征及影响因子方面的研究进展,在此基础上梳理物理概念预测模型。研究显示:海温异常是影响各区域雨季的重要先兆信号,但不同雨季的年际和年代际变化特征不同,海温作为外强迫信号的影响程度和时空形式也有差异。利用热带太平洋东西海温差指标能更好地解释华南前汛期降水的年际变化。而与梅雨的年际变化分量相关联的海温关键区主要分布于热带,与年代际或多年代际变化分量相联系的海温关键区则来自中高纬度。华北雨季降水的强弱不仅与ENSO循环的位相有关,更多受到ENSO演变速率的影响。而影响华西秋雨的海温关键区随着年代际背景的变化发生了改变,需要重新诊断和建模。