2014年秋季长株潭城市群一次典型霾污染天气过程的气象特征及成因分析

利用长株潭地区地面空气质量监测资料、常规地面气象资料及NCEP再分析资料和MODIS火点监测资料,结合HYSPLIT4后向轨迹模式,对2014年10月1718日长株潭地区一次严重霾天气过程的空气污染特征和成因进行综合分析。研究表明,长株潭地区此次严重霾天气污染事件的主要污染物为PM2.5,安徽南部和江西西北部地区秸秆焚烧产生的颗粒物,经高空偏东北气流引导输送到长株潭地区,是这次大范围烟霾天气的主要来源。长株潭地区西部高空槽区宽广,槽前西南气流较为强盛,地面受均压场控制,水平风速弱,为严重霾污染天气的维持提供了有利的环流条件。中低层逆温和大气底层湿度的增加,使污染物粒子不断累积;近地面连续静（小）风和风向的频繁转变,不利于污染物粒子的水平扩散;中下层弱的下沉气流、较低的混合层高度有利于污染物的垂直累积,为此次重度霾污染天气的发展、加强提供了有利的气象条件。     

Assessment of the Pacific decadal oscillation’s contribution to the occurrence of local torrential rainfall in north China

On 21–22 July 2012, torrential rains hit North China, with the daily precipitation record at Beijing station reaching 160.6 mm; this event is named the Beijing 7–21 case. This paper assesses the likelihood of the occurrence of local torrential rains, such as the Beijing 7–21 case, from the perspective of climate variability. In particular, the influence of the Pacific Decadal Oscillation (PDO) is assessed. There were five extreme events, with daily precipitation records equal to or larger than 160.6 mm, at Beijing station during the period 1951–2012; all of these events happened during negative phases of the PDO. The present analysis indicates that precipitation events more extreme than the Beijing 7–21 case should happen more than once per decade during negative phases of the PDO, but only about once every four decades during positive PDO phases. The negative phase of the PDO is found to be associated with a much greater probability of daily records of southerly winds in North China during summer. Strong southerly summer monsoons are deemed favorable for increasing the occurrence of local extreme rainfall over North China.     

渤海海效应暴雪云特征的观测分析

利用静止卫星 (GMS-5, GOES-9, MTSAT) 红外数据与CloudSat卫星云剖面雷达数据、NCEP FNL分析资料与常规观测资料,对2001—2010年发生的12次渤海海效应暴雪过程中云的演变特征、渤海热力作用与暴雪云团垂直结构及相态组成进行了观测分析。发现不同生成源地的暴雪云通常在渤海上快速发展,云中多存在水平范围可达100~300 km的密实条状或块状云团,其下对应主要降雪区域;暴雪云生成源地可分为渤海湾及莱州湾附近、渤海中部、辽东湾附近3种,暴雪云在海上移动主要受850 hPa风场影响;渤海暖海面与其上冷空气间的热量、水汽交换形成的不稳定层结条件,导致暴雪云进一步发展;暴雪云发展旺盛时期高度可达4 km,其冰水含量最大值达600 mg·m-3且主要集中在2 km高度附近,平均值可达303 mg·m-3,冰粒子有效半径最大值约为120 μm,平均值约为91 μm。     

一次暴雪过程前后近地层物理量场特征分析

利用铁塔风梯度观测资料和超声风温仪观测资料,对2008年1月18—21日暴雪前后,湖北黄石长江岸边近地层风场和湍流作了计算分析,探索其异常变化特征,为认识黄石地区暴雪近地层发生发展的物理过程提供依据。结果表明,暴雪前,风向转变,水平风速和垂直风速明显增大,湍流通量的输送较活跃,湍流动能和湍流强度有显著峰值出现;降雪过程结束后,湍流动能再次增大后缓慢减弱。可见此次暴雪过程前后近地层物理量场有异常变化     

Alteration and mineralization styles of the orogenic disseminated Zhenyuan gold deposit,southeastern Tibet: Contrast with carlin gold deposit

Orogenic disseminated and Carlin gold deposits share much similarity in alteration and mineralization.The disseminated orogenic Zhenyuan Au deposit along the Ailaoshan shear zone,southeastern Tibet,was selected to clarify their difference.The alteration and mineralization from the different lithologies,including meta-quartz sandstone,carbonaceous slate,meta-(ultra)mafic rock,quartz porphyry and lamprophyre were researched.According to the mineral assemblage and replacement relationship in all types of host rocks,two reactions show general control on gold deposition:(1)replacement of earlier magnetite by pyrite and carbonaceous material;(2)alteration of biotite and phlogopite phenocrysts in quartz porphyry and lamprophyre into dolomite/ankerite and sericite.Despite the lamprophyre is volumetrically minor and much less fractured than other host rocks,it contains a large portion of Au reserve,indicating that the chemically active lithology has played a more important role in gold precipitation compared to structure.LA-ICP-MS analysis shows that Au mainly occurs as invisible gold in fine-grained pyrite disseminated in the host rocks,with Au content reaching to 258.95 ppm.The diagenetic core of pyrite in meta-quartz sandstone enriched in Co,Ni,Mo,Ag and Hg is wrapped by hydrothermal pyrite enriched in Cu,As,Sb,Au,Tl,Pb and Bi.Different host rock lithology has much impact on the alteration and mineralization features.Carbonate and sericite in altered lamprophyre show they have higher Mg than those developed in other of host rocks denoting that the carbonate and sericite incorporated Mg from phlogopite phenocrysts in the primary lamprophyre during alteration.The ore fluid activated the diagenetic pyrite in meta-quartz sandstone leading the hydrothermal pyrite enriched in Cu,Mo,Ag,Sb,Te,Hg,Tl,Pb and Bi,but the hydrothermal pyrite in meta-(ultra)mafic rock is enriched in Co and Ni as the meta-(ultra)mafic rock host rock contain high content of Co and Ni.However,Au and As shear similar range in both types of host rocks indicating that these two elements most likely come from the deep source fluid rather than the host rocks.It was shown in the disseminated orogenic gold deposit that similar hydrothermal alteration with mineral assemblage of carbonate(mainly dolomite and ankerite),sericite,pyrite and arsenopyrite develops in all types of host rocks.This is different from the Nevada Carlin type,in which alteration is mainly dissolution and silicification of carbonate host rock.On the other hand,Au mainly occur as invisible gold in both disseminated orogenic and Carlin gold deposits.     

基于WebGIS的区域震害快速评估系统设计与实现

在进行大规模城乡震害预测工作中,需要使用与传统预测方式不同的新模型及新方法,以便实现震害快速预测及结果共享。利用人口普查数据等基础数据库,根据人口数据及灾害损失的关系模型,基于WebGIS技术,采用三层体系网络架构(由后台数据库、应用服务器(地图服务器)+Web服务器、客户端组成),利用VB+ArcObject服务器组件开发技术,通过动态链接库技术实现了在Ar-cIMS下的地图动态更新、动态预测及动态发布功能,实现了具有B/S结构的震害预测管理信息系统。该系统具有投入少、数据自动预测、定期更新且易于获取等优点,实现了地震震害信息共享     

Soil organic carbon storage and soil CO<Subscript>2</Subscript> flux in the alpine meadow ecosystem

High-resolution sampling, measurements of organic carbon contents and ¹⁴C signatures of selected four soil profiles in the Haibei Station situated on the northeast Tibetan Plateau, and application of ¹⁴C tracing technology were conducted in an attempt to investigate the turnover times of soil organic carbon and the soil-CO₂ flux in the alpine meadow ecosystem. The results show that the organic carbon stored in the soils varies from 22.12×10⁴ kg C hm⁻² to 30.75×10⁴ kg C hm⁻² in the alpine meadow ecosystems, with an average of 26.86×10⁴ kg C hm⁻². Turnover times of organic carbon pools increase with depth from 45 a to 73 a in the surface soil horizon to hundreds of years or millennia or even longer at the deep soil horizons in the alpine meadow ecosystems. The soil-CO₂ flux ranges from 103.24 g C m⁻² a⁻¹ to 254.93 gC m⁻² a⁻¹, with an average of 191.23 g C m⁻² a⁻¹. The CO₂ efflux produced from microbial decomposition of organic matter varies from 73.3 g C m⁻² a⁻¹ to 181 g C m⁻² a⁻¹. More than 30% of total soil organic carbon resides in the active carbon pool and 72.8%281.23% of total CO₂ emitted from organic matter decomposition results from the topsoil horizon (from 0 cm to 10 cm) for the Kobresia meadow. Responding to global warming, the storage, volume of flow and fate of the soil organic carbon in the alpine meadow ecosystem of the Tibetan Plateau will be changed, which needs further research. Supported by the National Natural Science Foundation of China (Grant Nos. 40231015, 40471120 and 40473002) and the Guangdong Provincial Natural Science Foundation of China (Grant No. 06300102)     

基于WRF-VAR的卫星资料同化分析检验试验

利用YHGSM 0.25°×0.25°高分辨数值产品作为背景场资料,使用WRF模式与WRF-VAR同化系统对中国区域进行连续一个月(2009年7月1～31日)的模拟试验,试验分为3组:(1)不同化任何资料,(2)同化常规资料,(3)同化ATOVS卫星资料;对3组试验进行了形势场检验和Ts评分.结果表明,第(2)、(3)...     

Structures and characteristics of the windy atmospheric boundary layer in the South China Sea region during cold surges

An observational analysis of the structures and characteristics of a windy atmospheric boundary layer during a cold air outbreak in the South China Sea region is reported in this paper. It is found that the main structures and characteristics are the same as during strong wind episodes with cold air outbreaks on land. The high frequency turbulent fluctuations(period<1 min) are nearly random and isotropic with weak coherency, but the gusty wind disturbances(1 min相似文献