北京中央商务区(CBD)城市热岛效应的研究     

程志刚  李炬  周明煜  窦军霞  曹晓彦  张京江  张鑫宇  贺晓冬 《气候与环境研究》2018,23(6):633-644

利用2012~2013年北京中央商务区（Central Business District,CBD）加密观测资料,分析CBD区域城市热岛（Urban Heat Island,UHI）强度日变化和空间变化特征及其影响因子。研究发现,CBD区域气温高于周边自动站气温,平均偏高0.64℃;CBD区域城市热岛强度呈现夜间强、白天弱的现象,中午甚至存在“城市冷岛”现象。季节平均UHI日变化表现为:在夜间,秋季最强,冬季次之,春季和夏季较弱;在白天,夏季最强,冬季次之,春季和秋季较弱。相对于晴朗无风天气,雾、雨、大风等天气对城市热岛有抑制作用,并结合小波分析结果发现,秋季城市热岛强度强于冬季是由于冬季雾、雨、大风等天气过程发生比例较高的缘故。CBD区域城市热岛空间变化特征研究发现,花园、学校等绿地有助于缓解城市热岛效应。雾日、雨日和大风日的CBD区域城市热岛强度空间变化标准差比晴朗无风日小。  相似文献   

辽宁中部城市群灰霾污染的外来影响   总被引：1，自引：0，他引：1  

洪也  杨婷  王喜全  马雁军  关颖  张云海  周德平  王扬锋  刘宁微 《气候与环境研究》2015,20(6):675-684

利用MODIS(MODerate-resolution Imaging Spectroradiometer)卫星资料、空气质量监测资料、地面气象资料及后向轨迹方法,对辽宁中部城市群代表性城市——沈阳市2009年全年发生的30 d首要污染物为PM10(空气动力学当量直径小于等于10μm的颗粒物,即可吸入颗粒物)且空气污染指数API(Air pollution Index)为3级及以上污染过程的天气形势及污染来源进行了综合分析。研究结果表明:引发3级以上重污染事件的天气形势主要为4类,分别为高压均压场型(包括高压后均压场型、高压前均压场型和高压内均压场型)、长白山小高压型、弱低压场型及地形槽型。发生污染天气时气流主要有两个来向,即西南方向的京津冀来向和偏北方向的内蒙和长春来向。气流来自偏南方向的天数最多,为19 d。其中最容易受京津冀影响的天气型为高压后均压场型和地形槽型,共有8 d,占总污染天数的26.7%。因此,来自京津冀的外来输送对于辽宁中部城市群霾污染的影响不容小视,辽宁中部城市群空气质量的改善与临近区域的改善紧密相关。  相似文献   

中央气象台天气预报服务业务的过去、现在和将来     

端义宏 《气象》2010,36(7):5-11

中央气象台成立到今天,已经走过60年的风雨历程。文章回顾中央气象台天气预报业务的发展历程、总结中央气象台天气预报业务的现有成就、展望中央气象台预报业务的未来,使我们更加坚定预报业务发展的信心。  相似文献   

闽中地区马面山群东岩组变质岩形成的古构造环境研究   总被引：9，自引：0，他引：9  

张达  吴淦国  彭润民  吴建设  狄永军  张祥信  汪群峰 《地学前缘》2005,12(1):310-320

闽中地区马面山群东岩组地层主要为绿片岩为主的一套古火山沉积建造。其主要岩性类型包括各种成分的绿片岩、大理岩、石英片岩及变粒岩类。绿片岩显示海底火山喷发特征,变粒岩原岩为中酸性岩类。东岩组变质岩岩石化学研究表明,绿片岩的原岩应为玄武岩类。变粒岩类主要属于英安岩及流纹岩。这些特征反映东岩组具双峰式火山岩特征,形成于大陆内部张性环境。绿片岩稀土元素特征也显示和大陆拉张环境中的火山岩类稀土特征非常相似,属大陆拉斑玄武岩;微量元素分布显示出该组变质岩原岩类似于大洋岛和大陆裂谷的板内碱性玄武岩。因此闽中地区中元古代可能处于板内古裂谷环境。  相似文献   

Overpressure preventing quartz cementation? - A reply     

《Marine and Petroleum Geology》2017

Chemical compaction and the relative importance of the pressure dissolution and illite-mica induced dissolution (IMID) models have remained a contentious issue, as is the role played by stress in chemical compaction. This paper offers further support and evidence as discussed in Stricker et al. (2016b), focusing on the reservoir quality of the Triassic Skagerrak Formation sandstones in the high pressure high temperature (HPHT) Central Graben, North Sea. The reply discusses alterative reservoir quality interpretations and comments as raised by Maast (2016). A series of theoretical and experimental studies, as well as field based evidence is presented providing strong support to the important role of stress (e.g. vertical effective stress) during chemical compaction. The evidence leads to the conclusion that the process of chemical compaction is stress and temperature driven and significantly enhanced by clay minerals, playing a catalytic role by increasing the width of diffusion pathway or by modifying the kinetics of the dissolution process.  相似文献   

The use of diagenetic signatures to distinguish marine from continental deposits in Triassic-Jurassic sandstone reservoirs from the UK Central Graben     

《Marine and Petroleum Geology》2017

Poor biostratigraphic control for some Triassic-Jurassic successions in the North Sea Basin and sub-basins necessitates the use of alternative correlation methods. This study examines the use of diagenetic signatures to distinguish continenetal from marine sandstone successions (Triassic-Jurassic) in the UK Central Graben. The key diagenetic alterations encountered in these successions include kaolinitization of the framework grains and the development of sphaerosiderite and pyrite. The δ ¹³C_V-PDB values of siderite (−8.1 to −8.5‰) and of ankerite (−10.8 to −9.2‰), indicate a strong contribution of dissolved carbon from the decay of plant material in soil. However, marine water likely influenced diagenesis during periods of relative sea level rise by providing the dissolved sulfate (SO₄²⁻) required for the precipitation of pyrite. The presence of diagenetic alterations such as kaolinitization of framework grains and cementation by sphaerosiderite could indicate that the sediments were deposited in an overall continental setting. However, the occurrence of pyrite and scattered grains of deep-green colored glauconite suggests occasional marine influence. Such information on the changes of the diagenetic realm provides important clues for establishing a framework for stratigraphic correlations. Caution should be exercised when interpreting petrographic data as subsequent episodes of telodiagenesis can complicate petrographic interpretations.  相似文献   

The impact of syn- and post-extension prograding sedimentation on the development of salt-related rift basins and their inversion: Clues from analogue modelling     

《Marine and Petroleum Geology》2017

Various studies have demonstrated the intrinsic interrelationship between tectonics and sedimentation in salt-related rift basins during extension as well as during their inversion by compression. Here, we present seven brittle–ductile analogue models to show that the longitudinal or transverse progradation of sediment filling an elongate extensional basin has a substantial impact on the growth of diapirs and their lateral geometrical variations. We use five extensional models to reveal how these prograding systems triggered diapir growth variations, from proximal to distal areas, relative to the sedimentary source. In the models, continuous passive diapir walls developed, after a short period of reactive–active diapiric activity, during syn-extensional homogeneous deposition. In contrast, non-rectilinear diapir walls grew during longitudinal prograding sedimentation. Both longitudinal and transverse post-extensional progradation triggered well-developed passive diapirs in the proximal domains, whereas incipient reactive–active diapirs, incipient roller-like diapirs, or poorly developed diapirs were generated in the distal domains, depending on the modelled sedimentary pattern. Two models included final phases of 6% and 10% shortening associated with basin inversion by compression, respectively, to discriminate compressional from purely extensional geometries. With the applied shortening, the outward flanks of existing diapir walls steepened their dips from 8°–17° to 30°–50°. Likewise, 6% of shortening narrowed the diapir walls by 32%–72%, with their fully closing (salt welds) with 10% of shortening. We compare our results with the distribution of salt walls and minibasins of the Central High Atlas diapiric basin in Morocco, which was infilled with a longitudinally prograding mixed siliciclastic and carbonatic depositional sequence during the Early–Middle Jurassic with a minimum thicknesses of 2.5–4.0 km.  相似文献   

Reconstructing the tsunami record in Tirúa,Central Chile beyond the historical record with quartz-based SAR-OSL     

《Quaternary Geochronology》2015

The most recent high magnitude seismic events, e.g. the M_w 8.2 Iquique earthquake (April 1st, 2014) and the M_w 8.8 Maule earthquake (February 27th, 2010) are reminders of the pronounced vulnerability of the Chilean coast to the impact of natural hazards like earthquakes and tsunamis. Therefore it is crucial to understand the complex tsunami history of Chile which can be deciphered by studying the geological record of former tsunamis in the form of tsunami deposits.At the coastal locality of Tirúa (Central Chile) six distinct, successive tsunamigenic sand layers are intercalated in fine grained floodplain sediments. We present the optically stimulated luminescence (OSL) analysis of quartz from samples of this sedimentological river marsh profile of 1.5 m depth.After the assessment of the applicability of OSL to these samples, it could be noted that despite of an expected low OSL sensitivity of the quartz from the South American Cordillera, most of the sampled quartz yielded a detectable natural signal. After performance tests according to the SAR-protocol, the measurements of the different tsunami sand layers were conducted with small (2.5 mm) aliquots of quartz with the preheat temperature 180 °C. The calculation of D_e was provided by applying both the central age and minimum age models. All samples are heterogeneous in their D_e distributions due to incomplete or absent significant bleaching during transport by tsunami. The resulting ages of the tsunami sediments yield an offset of nearly 200 years for CAM ages and less than 50 years for MAM ages, consequently favouring MAM ages for true burial age determination. In some tsunami sand layers and their surrounding river marsh sediments age inversions occur. They were caused by the initial deposition of well bleached sediments derived from beach and dunes followed by older sediments redeposited from beach and intertidal environments during tsunami flow. Despite the offset and age inversion six different tsunami events were dated in the Tirúa profile. Three of these events extend the historical record to pre-Columbian time with the oldest tsunami dated to over 1500 years before present.  相似文献   

Food web and fish stock changes in central Chile: comparing the roles of jumbo squid (Dosidicus gigas) predation,the environment,and fisheries     

《Deep Sea Research Part II: Topical Studies in Oceanography》2013

We analyzed recent food web and fish stock changes in the central Chile marine ecosystem, comparing the roles of jumbo squid (Dosidicus gigas) as predator, the environment, and fishing. To accomplish this we used food web modeling and the Ecopath with Ecosim software (EwE). The principal fish stocks have experienced wide decadal fluctuations in the past 30 years, including stock collapses of horse mackerel (Trachurus murphyi) and hake (Merluccius gayi), and there was a large influx of jumbo squid during the mid-2000s. We used two EwE models representing the food web off central Chile to test the hypothesis that predation by jumbo squid has been significant in explaining the dynamics of the main fishing resources and other species in the study area. Results indicate that predation by jumbo squid on fish stocks is lower than that of other predators (e.g. hake) and the fishery. Long-term fluctuations (1978–2004) in the biomass of the main fish stocks (as well as other components of the food web) seem to be related to fishing and to variation in primary production, rather than to predation by jumbo squid alone. Jumbo squid seems to play a role as predator rather than prey in the system, but its impacts are low when compared with the impacts of other predators and fishing. Therefore, we conclude that jumbo squid predation on its prey was not the primary force behind the collapse of important fish stocks off central Chile. Future efforts should be directed to better understanding factors that trigger sudden increases in jumbo squid abundance off central Chile, as well as modeling its trophic impacts.  相似文献   

我国中部六省产业集聚与扩散的空间计量   总被引：1，自引：0，他引：1  

宋马林  王舒鸿  黄蓓  胡百红 《地理研究》2012,31(3):534-542

＂中部崛起＂战略给中部六省各地区的大发展带来了新的机遇。进入十二五时期,中部地区有必要总结之前发展过程中的经验,从产业结构调整和升级着手,掌握产业更新规律,尽可能规避经济发展中的不利因素,实现产业结构升级承托的区域经济跨越式可持续发展。本文收集整理了我国中部六省共88个地市2000年至2008年第二产业数据,采用LIS...  相似文献