以用户为导向的交互式预报系统及应用研究

基于近年来涌现的有关新一代气象预报系统发展的认识,本文提出用户导向的交互式预报系统的概念模型。新系统强调在用户信息分析的基础上,发展从用户出发再回到用户不断自我改善的预报流程。系统组成的关键模块包括：用户端风险决策动态需求分析模块、物理预测模块、用户目标量的降尺度模块,用户端专业耦合模块及用户风险决策模块。文中阐述了系统中各模块间的联系、用户端信息在系统中的反馈作用以及具体的“交互式”方式。以临沂地区水文用户为例,以引发洪涝的降水事件为预报对象,利用TIGGE全球超集合预报,初步构建了一个临沂水文用户导向的可能致洪降水交互式预报系统。这个具备迭代式自我完善功能的新型预报系统包含了汛期随时变化的用户决策信息、由前期影响雨量和当前水文条件决定的可变致洪降水阈值以及一个动态的用户端预报水平和不确定性评估模块。初步结果表明,结合用户端信息的预报优于未考虑用户信息的预报结果,从而更直接地帮助用户进行防汛决策。个例研究也为发展更完整的用户导向预报系统提供了参考。     

尚未完成的地质年代表--第四纪悬而未决的前程

第四纪是以气候变化、人类出现和现生生物物种占优势为特征的最新地质时期。第四纪的地层多以松散沉积物为主,是人类赖以生存居住的主要场所。鉴于第四纪研究对地质学,地球系统科学和全球变化科学的贡献,近几十年来学术界和公众对其产生极大兴趣和更加重视。为了回应2 0 0 4年春国际地层委员会提出的“国际地层表”( 2 0 0 4 ) ,详细地介绍了国际第四纪联合会为争取第四纪在地质年表中的合理地位所作的努力以及目前争论的结果:今年比利时最终定论。呼吁我国广大的第四纪工作者积极加入到支持国际第四纪联合会保留第四系作为独立地层单元的行列中。同时简略地介绍了第四纪(系)术语的来由,国内外关于第四纪下限研究的历史和现状     

Sensitivity of GPS and GLONASS orbits with respect to resonant geopotential parameters

The Center for Orbit Determination in Europe (CODE) has been involved in the processing of combined GPS/GLONASS data during the International GLONASS Experiment (IGEX). The resulting precise orbits were analyzed using the program SORBDT. Introducing one satellites positions as pseudo-observations, the program is capable of fitting orbital arcs through these positions using an orbit improvement procedure based on the numerical integration of the satellites orbit and its partial derivative with respect to the orbit parameters. For this study, the program was enhanced to estimate selected parameters of the Earths gravity field. The orbital periods of the GPS satellites are —in contrast to those of the GLONASS satellites – 2:1 commensurable (P _Sid:P _GPS) with the rotation period of the Earth. Therefore, resonance effects of the satellite motion with terms of the geopotential occur and they influence the estimation of these parameters. A sensitivity study of the GPS and GLONASS orbits with respect to the geopotential coefficients reveals that the correlations between different geopotential coefficients and the correlations of geopotential coefficients with other orbit parameters, in particular with solar radiation pressure parameters, are the crucial issues in this context. The estimation of the resonant geopotential terms is, in the case of GPS, hindered by correlations with the simultaneously estimated radiation pressure parameters. In the GLONASS case, arc lengths of several days allow the decorrelation of the two parameter types. The formal errors of the estimates based on the GLONASS orbits are a factor of 5 to 10 smaller for all resonant terms. AcknowledgmentsThe authors would like to thank all the organizations involved in the IGS and the IGEX campaign, in particular those operating an IGS or IGEX observation site and providing the indispensable data for precise orbit determination.     

On the global stratotype section and point of the Triassic base

A unique succession of volcanogenic deposits with representative paleontological remains characterizing the Permian-Triassic boundary interval in the North Siberian platform and Taimyr is described. The succession is suitable for selecting a standard for the Triassic base in nonmarine deposits. Abundant and diverse fossils occurring in the succession evidence that volcanism responsible for origin of the plateau basalt province in Siberia was not a brief epoch of paroxysmal eruptions, which eliminated everything alive. Throughout the formation history of relevant plateau basalts, the organic world of the plateau and around existed and gradually evolved.     

全球碳循环研究中的δ13C方法及其进展

随着分析技术的进步,δ13C观测在全球碳循环研究中越来越受到重视。在讨论关于碳循环中δ13C的Suess效应、分布特征和同位素分馏等基本概念的基础上,结合现有的观测事实,介绍应用δ13C辨别碳的源汇问题的方法,通过比较不同KeelingPlot方法分析该方法在研究大气CO2背景特征中的意义。着重讨论δ13C在研究大气C...     

非差非组合电离层加权PPP-RTK/INS紧组合模型

PPP-RTK是一种可实现快速模糊度固定的精密单点定位（PPP）技术,它的组成包括由多个接收机构成的网端用于生成各类精密改正产品,以及单站构成的用户端以实现快速高精度定位.当网端是中等尺度参考网,即参考站之间的站间距在百余公里,有必要引入电离层加权模型,其优势在于能够增强PPP-RTK函数模型.此外,从非差非组合观测值层面出发,其能够兼容单/双频用户.然而,单凭卫星导航定位技术很难在复杂环境下提供连续导航定位服务.本文从理论到应用,基于非差非组合电离层加权PPP-RTK模型,构建了单/双频PPP-RTK/INS紧组合模型.在距离最近参考站约70 km的区域进行了两次车载实验,并分别利用单/双频PPP-RTK以及PPP-RTK/INS紧组合模型的实时处理结果进行分析.结果表明,双频PPP-RTK/INS紧组合在半城市环境能从分米级定位提升至厘米级定位,重收敛时间从11 s提升至3.6 s.以水平偏差小于0.2 m评估定位可用率,双频PPP-RTK/INS紧组合模型在半城市环境和复杂城市环境中分别可实现100%和96.97%.考虑车道级定位,单频PPP-RTK/INS紧组合模型在半城市和复杂城市环境内分别可实现分米以及亚米级定位,其在水平偏差在0.5 m内的可用率分别为98.97%和76.1%.

     

GPM双频降水测量雷达对降雪的探测能力分析

以双频降水测量雷达为主载荷的GPM卫星于2014年2月发射升空。由于轨道倾角以及仪器通道的设置,大大提升了对弱降水和降雪的探测能力。通过四次降雪个例,分析比较了双频降水测量雷达的三种扫描模式(Ku,KaMS和KaHs)对降雪探测能力的差异。结果表明:DPR相态产品和地面实际观测结果比较一致,固态降雪温度-0.5℃并且降雪发生时的风暴顶高度大多6 km。Ku波段雷达由于仪器灵敏度的大幅提高.对降雪的综合探测能力最强,而KaMs和KaHS也具有特定的作用。此外,为了保证衰减订正的精度,和非降雪部分的衰减相比,需要主要提高降雪衰减尤其是混合相态湿雪的衰减订正精度。     

The inhibition of marine nitrification by ocean disposal of carbon dioxide

In an attempt to reduce the threat of global warming, it has been proposed that the rise of atmospheric carbon dioxide concentrations be reduced by the ocean disposal of CO2 from the flue gases of fossil fuel-fired power plants. The release of large amounts of CO2 into mid or deep ocean waters will result in large plumes of acidified seawater with pH values ranging from 6 to 8. In an effort to determine whether these CO2-induced pH changes have any effect on marine nitrification processes, surficial (euphotic zone) and deep (aphotic zone) seawater samples were sparged with CO2 for varying time durations to achieve a specified pH reduction, and the rate of microbial ammonia oxidation was measured spectrophotometrically as a function of pH using an inhibitor technique. For both seawater samples taken from either the euphotic or aphotic zone, the nitrification rates dropped drastically with decreasing pH. Relative to nitrification rates in the original seawater at pH 8, nitrification rates were reduced by ca. 50% at pH 7 and more than 90% at pH 6.5. Nitrification was essentially completely inhibited at pH 6. These findings suggest that the disposal of CO2 into mid or deep oceans will most likely result in a drastic reduction of ammonia oxidation rates within the pH plume and the concomitant accumulation of ammonia instead of nitrate. It is unlikely that ammonia will reach the high concentration levels at which marine aquatic organisms are known to be negatively affected. However, if the ammonia-rich seawater from inside the pH plume is upwelled into the euphotic zone, it is likely that changes in phytoplankton abundance and community structure will occur. Finally, the large-scale inhibition of nitrification and the subsequent reduction of nitrite and nitrate concentrations could also result in a decrease of denitrification rates which, in turn, could lead to the buildup of nitrogen and unpredictable eutrophication phenomena. Clearly, more research on the environmental effects of ocean disposal of CO2 is needed to determine whether the potential costs related to marine ecosystem disturbance and disruption can be justified in terms of the perceived benefits that may be achieved by temporarily delaying global warming.     

Neogene sequence stratigraphic architecture of the Nile Delta,Egypt: A micropaleontological perspective

The sequence stratigraphic architecture of the Neogene section from the subsurface Nile Delta is resolved based on exceptionally well-preserved microfossils from the offshore NDOB-1 borehole. The architecture is configured on bathymetry variations and statistical parameters as deduced from the relative abundance of foraminiferal associations. The statistical parameters include ratios of planktic versus benthic foraminifera, and cluster and correspondence analysis of the twelve most commonly used benthic foraminiferal genera as proxies of water depths. The combination of cluster and correspondence analysis was employed to decipher the evolution and dynamics of the basin and the mechanisms that controlled the deposition of Neogene sequences in the Nile Delta region. Four basic environmental settings were recognized: 1.) a middle to outer neritic eutrophic setting, 2.) a middle to outer neritic mesotrophic setting, 3.) an outer neritic to upper bathyal mesotrophic setting and 4.) an upper bathyal mesotrophic setting.Eight stratigraphic sequences were identified in the Neogene Nile Delta section. Three sequence in the Miocene (MSeq1, MSeq2 and MSeq3), three in the Pliocene (PSeq1, PSeq2 and PSeq3) and two in the Pleistocene (PtSeq1 and PtSeq2). These sequences are systematically measured and described in terms of time, space and water bathymetry. The sequence boundaries and flooding surfaces were dated using high-resolution microfossil biochronology and stratigraphic index markers. Individual sequences and boundaries were correlated with international and local sequence stratigraphic models. The new sequence stratigraphic model established here provides age calibrated surfaces for inter-basinal correlations and opens new avenues for hydrocarbon reservoir exploration.     

Geographical distribution of fish catches and temperature variations in the northeast Atlantic since 1945

Warming of the northeast Atlantic is expected to affect the location and productivity of fish stocks. It is examined whether variations in catches of cod, herring, mackerel, anchovy and sardines in the ICES statistical areas are related to variations in ocean temperature. Temperatures at certain locations along the Norwegian coast are taken as proxies for temperatures in the Norwegian Sea and the North Sea. It is found that the catches of cod in the North Sea are inversely correlated with temperature and that recruitment and catches of cod in the Norwegian Sea and the Barents Sea are positively related to temperature. There is also some indication of a positive correlation between temperature and the catches of mackerel in the North Sea and the Norwegian Sea, and between temperature and the catches of sardines in the North Sea.