北京城区近地面比湿和风场时空分布特征

利用2008—2012年北京城区平均5 km的高密度自动气象站逐时观测数据,分析了北京城区近地面比湿、风向和风速的时空精细分布特征,初步探究了城市下垫面对局地气象要素的影响机制。研究表明:夏季白天北京城区为干岛,冬季城区表现为弱湿岛特征。受城市效应的影响,北京城区与郊区比湿日变化有明显差异。近地面10 m风受到地形、城市和季节性盛行风的共同影响。当气流经过城区时有明显的绕流现象。夏季05:00—10:00 (北京时,下同),受山风、弱的夏季偏南风和城市热岛共同作用,气流向城市中心辐合。冬季15:00—19:00,受季节盛行风偏北气流和谷风偏南气流的共同作用,在城区形成一条西北—东南走向的辐合线。对风速研究发现:城市粗糙下垫面使北京城区风速减小,二环路和三环路之间存在一条“n”状的风速小值带。由此可见,除已开展较多研究的城市热岛效应外,北京城市效应对近地面湿度和风场亦有显著影响。     

西藏色齐拉山地区立体气候特征初步分析

利用西藏色齐拉山地区不同海拔高度的8个自动站和3个实测气象站1年的近地面观测资料,分析了该地区气温、地温、降水量、湿度和风速等气象要素的季节变化特征,探讨了东、西坡局地气候特征差异形成的原因。结果表明：色齐拉山地区1月为最冷月、7月为最暖月;月平均最高气温、最低气温与平均气温的季节变化一致。气温日较差大年较差小。年平均气温直减率东、西坡分别为0．54℃／100m和0．73℃／100m,西坡大于东坡。地气温差冬季西坡大于东坡,夏季东坡大于西坡。年、月平均地温直减率西坡仍大于东坡;东坡除夏季7、8月份外,地温直减率小于气温直减率;西坡除冬季（12月和1月）,地温直减率大于气温直减率。降水量东坡比西坡多,海拔2500m以上地区4～10月降水总量随着海拔高度的升高呈增加趋势,增加率为20．9mm／100m。空气相对湿度冬季低夏季高,年变化呈单峰型。东、西坡冬季风速较强夏季相对较弱,初春风速最大。东、西坡气候差异与海拔高度、坡向、下垫面性质有关。     

Effects of climate change and agronomic practice on changes in wheat phenology

Phenological changes in crops affect efficient agricultural production and can be used as important biological indicators of local and regional climate change. Although crop phenological changes and their responses to climate change, especially temperature, have been investigated, the impact of agronomic practice such as cultivar shifts and planted date changes on crop phenology remains unclear. Here, we used a long-term dataset (1981–2010) of wheat phenology and associated local weather data from 48 agro-meteorological stations in four temperature zones in China to analyze phenological changes of spring and winter wheat. Trend analysis method was used to estimate changes in the date of growth stages and the duration of growth phases, while sensitivity analysis method was used to qualify the response of growth phase duration to mean temperature (T_mean), total precipitation (PRE), and total sunshine duration (SSD). Using the Crop Environment Resource Synthesis-wheat model, we isolated the impacts of climate change, cultivar selection, and sowing date on phenological change of wheat. Results show that phenological changes were greatest in the warm-temperate zone. Sensitivity analysis indicates that growth phase duration was generally negatively related to T_mean and positively related to PRE and SSD. The positive sensitivity response to T_mean occurred in the tillering to jointing and sowing to maturity growth periods in the warmer temperature zones, suggesting that warmer temperatures during the overwintering period hampered effective vernalization in winter wheat. Modeling results further indicate that reductions in wheat growth duration caused by climate change could be offset by the introduction of new cultivars with high thermal requirements and accelerated with delayed sowing date.     

Radiation-induced defects in quartz. II. Single-crystal W-band EPR study of a natural citrine quartz

Single-crystal electron paramagnetic resonance (EPR) spectra of a natural citrine quartz without any artificial irradiation, measured at W-band frequencies (∼94 GHz) and temperatures of 77, 110 and 298 K, allow better characterization of three previously-reported Centers (#6, #7 and B) and discovery of three new defects (B′, C′ and G′). The W-band EPR spectra reveal that Centers #6 and #7 do not reside on twofold symmetry axes, contrary to results from a previous X-band EPR study. The W-band spectra also show that the previously reported Center B is a mixture of two defects (B and B′) with similar g matrices but different-sized ²⁷Al hyperfine structures. Center C′ has similar principal g values to the previously reported Center C but is distinct from the latter by a larger ²⁷Al hyperfine structure with splittings from 0.10 to 0.22 mT. Also, Center G′ has a similar g matrix to the previously reported Center G but a different ²⁷Al hyperfine structure with splittings from 0.41 to 0.53 mT. These spin-Hamiltonian parameters, together with observed thermal properties and microwave-power dependence, suggest that Centers #6 and #7 probably represent O₂³⁻ type defects. Centers B and B′ are probably superoxide radicals (O₂⁻) with the unpaired spin localized on the same pair of oxygen atoms around a missing Si atom but linked to a substitutional Al³⁺ ion each at different neighboring tetrahedral sites. Similarly, Centers G and G′ are most likely superoxide radicals with the unpaired spin localized on another pair of oxygen atoms around a missing Si atom and linked to a substitutional Al³⁺ ion each at different neighboring tetrahedral sites. Center C′ is probably an ozonide radical associated with a missing Si atom and linked to a substitutional Al³⁺ ion at the neighboring tetrahedral site. This study exemplifies the value of  high-frequency EPR for discrimination of  similar defect centers and determination of  small local structural distortions that are often difficult to resolve in conventional  X- and Q-band EPR studies.     

大同第四纪火山群的活动特点

一、引言大同第四纪火山群位于山西省大同县和阳高县境内(图1),包括近5年来在大峪口,秋林地区首次发现的6个小火山。该火山群大、小火山共计31个。大同火山群南以六棱山北麓断裂为界,分布于大同盆地东部的第四纪沉积区范围。火山群南侧的六棱山和北部的小北山是由前寒武花岗片麻岩组成的山地。     

应用延迟累加的微弱GPS信号捕获算法

针对在弱信号环境下传统算法无法进行捕获的问题,提出了一种改进算法。该算法在双块零拓展(double block zero padding,DBZP)算法的基础上,采用延迟累加的方法,首先将DBZP算法相关运算结果中被舍弃的部分暂存,然后对延迟1ms的接收信号进行相关运算,得到相应的相关运算结果,将其与存储的运算结果进行相干累加,并将相干累加结果作为捕获模块输出与门限值进行比较。改进算法在增加极少运算量的前提下,通过提高相关运算结果的利用率,增加了数据观测量。仿真结果表明,改进算法能够提高捕获算法处理增益,在捕获载噪比为17dB-Hz的信号时,检测概率能够达到91%。     

鱼类的耳石信息分析及生活史重建——理论、方法与应用

耳石(Otolith)是硬骨鱼类(Teleosts)在生长过程中沉积在内耳中的结石,主要矿物成分是CaCO3起声音接收和平衡定向作用。其内部轮纹(日轮Daily ring或年轮Annul ring)像在其他海洋动物特定钙化组织(如瓣鰓类外壳、珊瑚骨骼、多毛类颌骨、乌贼内壳、哺乳动物牙齿)中的轮纹一样随鱼类的发育而生长,并沉积着现场水环境中的主要化学元素。由于在形成过程中其轮纹形态结构与化学组成相当稳定,记录了鱼类个体生活过程中丰富的生物物理化学环境信息,所以,耳石信息分析可以揭示鱼类的生活史及其所经历的环境变化。在目前,耳石信息分析的应用涵盖了鱼类生态学研究的诸多方面,如鱼类的孵化和早期发育生长、产卵场和产卵期判定、仔鱼的运输过程(Larval transportation、年龄鉴定与种群鉴定(Age determination & population discrimination)、个体迁移(Migration)等。近年来,随着相关科学和技术的发展,它已经成为一种揭示鱼类生活史、生活史重建(Recastruction of life history)以及海洋环境域变(Regime shift)的关键技术,也是国际上渔业科学和海洋环境科学的研究热点。过去10年内三次国际鱼类耳石学术会议的成功举办(1993 Maryland-USA，Secor et al,1995a，1998- Bergen-Norway Fossum et al,2000；2004- Townsville Australia Begg et al,2005)大大推进了该研究领域的发展。其研究方向主要包括年龄鉴定与验证、显微结构分析(Microstructure)和微化学分析(Microchemistry)(Stevenson et al.,1992 ；Secor et al..1995a， Fossum et.al, 2000； Campana 1999， 2001； Elsdon et al, 2003a, b；Begg et al, 2005 )等。     

Morphodynamic Characteristics and Medium-Term Simulation of the North—South Passage Under the Impact of the Yangtze Estuary Deepwater Navigation Channel Project

The morphological evolution characteristics of the North-South Passage area since the construction of the Yangtze Estuary Deepwater Navigation Channel Project(DNCP) are analyzed on the basis of the measured data. A twodimensional morphodynamics numerical model of the Yangtze Estuary is established to verify the morphological evolution of the North-South Passage under the influence of the DNCP and to predict the future evolution in the next 40 years. Data analysis shows that the North Passage has experienced rapid adjustment stages and adaptive stages after the construction of the DNCP. Slow erosion occurred along the main channel, and slow siltation could be observed in the area between the groins. The South Passage showed a state of upper section erosion and down section deposition. At present, the whole South Passage is in a slight erosion state. According to the numerical model, the eroding and silting speed of the North Passage will slow down in the future. The present state that erosion occurs in the main channel and siltation occurs between the groins will continue. The South Passage will still maintain upper section erosion and down section deposition in the future. Due to the main channel erosion of the North Passage and siltation of the South Passage, the sediment division ratio of the North Passage will increase in the future but still be smaller than 50%. After morphological evolution of 40 years, the direction of residual sediment transport caused by M2 and M4 tidal components in the North Passage has not changed, but the transport rate will decrease. It is considered that the morphological evolution of the North-South Passage could reach a relatively stable state after 40 years.     

Fault linkage patterns and their control on the formation of the petroleum systems of the Erlian Basin, Eastern China

Fault linkage patterns in rift basins are very common. While the process of fault linkage may be very short, it changes sedimentation patterns before and after linkage and controls the development of half-grabens. The propagation and growth of boundary faults can be divided into a simple fault propagation pattern and a fault growth-linkage pattern. Based on structural style, sedimentation patterns and oil-source correlations in the Erlian Basin, three types of grabens and petroleum systems can be identified. The Abei graben is controlled by a single boundary fault and forms an independent petroleum system. The Saihantala graben is controlled by several linked faults, which also has an independent petroleum system. The Wuliyasitai Depression controlled by two boundary fault segments which results in two petroleum systems. As not all half-grabens develop one petroleum system; they may, therefore, have two or more systems. The relay ramps between fault segments before linkage are the locations of deposition of sands and conglomerates, and consequently, are the focus areas for stratigraphic–lithologic trap exploration.