Global Terrestrial Water Storage Changes and Connections to ENSO Events

Improved data quality of extended record of the Gravity Recovery and Climate Experiment (GRACE) satellite gravity solutions enables better understanding of terrestrial water storage (TWS) variations. Connections of TWS and climate change are critical to investigate regional and global water cycles. In this study, we provide a comprehensive analysis of global connections between interannual TWS changes and El Niño Southern Oscillation (ENSO) events, using multiple sources of data, including GRACE measurements, land surface model (LSM) predictions and precipitation observations. We use cross-correlation and coherence spectrum analysis to examine global connections between interannual TWS changes and the Niño 3.4 index, and select four river basins (Amazon, Orinoco, Colorado, and Lena) for more detailed analysis. The results indicate that interannual TWS changes are strongly correlated with ENSO over much of the globe, with maximum cross-correlation coefficients up to ~0.70, well above the 95% significance level (~0.29) derived by the Monte Carlo experiments. The strongest correlations are found in tropical and subtropical regions, especially in the Amazon, Orinoco, and La Plata basins. While both GRACE and LSM TWS estimates show reasonably good correlations with ENSO and generally consistent spatial correlation patterns, notably higher correlations are found between GRACE TWS and ENSO. The existence of significant correlations in middle–high latitudes shows the large-scale impact of ENSO on the global water cycle.     

复式钢管混凝土外肋环板节点抗剪承载力研究

在已有理论和试验研究的基础上,对复式钢管混凝土外肋环板节点的抗剪受力性能进行分析。建立了节点核心区的抗剪受力模型,将节点域抗剪贡献分为三部分:节点域内外钢管腹板的抗剪贡献、节点主要连接件竖向肋板与锚固腹板的抗剪贡献以及节点域混凝土的抗剪贡献,推导了复式钢管混凝土柱节点屈服抗剪承载力和极限抗剪承载力的计算公式,为复式钢管混凝土柱节点的工程设计提供承载力计算方法。理论得到的节点屈服剪力和极限剪力值与试验结果进行了对比,并提出抗剪能力储备系数这一新指标反映节点的抗剪切破坏能力,量化地解释了节点发生梁铰破坏后抗剪能力的安全储备。得出此类新型节点在破坏时抗剪储备能力充足,可保证节点达到良好延性的破坏模式,说明节点设计符合强剪弱弯的抗震设计原则。     

On the development mechanism of the lacustrine high-grade hydrocarbon source rocks of Chang 91 member in Ordos Basin

As revealed from recent drilling and organic geochemical testing and research, a series of lacustrine high-grade hydrocarbon source rocks was discovered in the upper section of the Chang 9 oil reservoir member of upper Triassic in Ordos Basin. The hydrocarbon source rocks show average TOC content as high as 5.03%, average bitumen “A” content as high as 0.8603%, and good quality organic precursors, which are of the sapropelic type mainly derived from lower aquatic plants and have reached the thermal evolution stage featured by oil-producing climax. Generally the lacustrine high-grade hydrocarbon source rocks were developed in local depressions of a lake basin, and the Chang 9₁ member was particularly formed in a depositional environment characterized by fresh water to weakly saline water, weakly oxidizing to weakly reducing setting and semi-deep lake facies, as was demonstrated by a variety of organic to inorganic geochemical parameters. As a result, high productivity constitutes the principal controlling force for generation of this series of high-grade hydrocarbon source rocks. Deposition of thinly-bedded and laminated tuffs as well as positive Eu anomaly corroborate the possible occurrence of anoxic geological event closely related to contemporaneous volcanic eruption, which would play a key part in development of the Chang 9₁ member of high-grade hydrocarbon source rocks.

     

On the development mechanism of the lacustrine high-grade hydrocarbon source rocks of Chang 9<Subscript>1</Subscript> member in Ordos Basin

As revealed from recent drilling and organic geochemical testing and research, a series of lacustrine high-grade hydrocarbon source rocks was discovered in the upper section of the Chang 9 oil reservoir member of upper Triassic in Ordos Basin. The hydrocarbon source rocks show average TOC content as high as 5.03%, average bitumen “A” content as high as 0.8603%, and good quality organic precursors, which are of the sapropelic type mainly derived from lower aquatic plants and have reached the thermal evolution stage featured by oil-producing climax. Generally the lacustrine high-grade hydrocarbon source rocks were developed in local depressions of a lake basin, and the Chang 9₁ member was particularly formed in a depositional environment characterized by fresh water to weakly saline water, weakly oxidizing to weakly reducing setting and semi-deep lake facies, as was demonstrated by a variety of organic to inorganic geochemical parameters. As a result, high productivity constitutes the principal controlling force for generation of this series of high-grade hydrocarbon source rocks. Deposition of thinly-bedded and laminated tuffs as well as positive Eu anomaly corroborate the possible occurrence of anoxic geological event closely related to contemporaneous volcanic eruption, which would play a key part in development of the Chang 9₁ member of high-grade hydrocarbon source rocks.     

Chronology and geochemistry of the volcanic rocks in Woruo Mountain region,northern Qiangtang depression: Implications to the Late Triassic volcanic-sedimentary events

A suite of sedimentary-volcaniclastic rocks intercalated with the volcanic rocks unconformably overlies the Triassic Xiaochaka Formation in the Woruo Mountain region, Qiangtang Basin, northern Tibet. The vitric tuff from the base of these strata gives a SHRIMP zircon U-Pb age of 216 ± 4.5 Ma, which represents the age of the Late Triassic volcanic-sedimentary events in the Woruo Mountain region, and is consistent with that of the formation of the volcanic rocks from the Nadi Kangri Formation in the Nadigangri-Shishui River zone. There is a striking similarity in geochemical signatures of the volcanic rocks from the Woruo Mountain region and its adjacent Nadigangri-Shishui River zone, indicating that all the volcanic rocks from the Qiangtang region might have the same magmatic source and similar tectonic setting during the Late Triassic. The proper recognition of the Late Triassic large-scale volcanic eruption and volcanic-sedimentary events has important implications for the interpretation of the Late Triassic biotic extinction, climatic changes and regressive events in the eastern Tethyan domain, as well as the understanding of the initiation and nature, and sedimentary features of the Qiangtang Basin during the Late Triassic-Jurassic.     

利用多台P波到时估测震中算法及程序

通过基于COM组件的VB与Matlab混合编程途径,实现已知区域P波速度条件下利用多台P波到时估测震中位置算法程序化,使用发现,该程序具有运行界面友好、速度快及对网内和网缘地震定位精度较好的优点.     

Large-Scale Environmental Influences on the Onset, Maintenance, and Dissipation of Six Sea Fog Cases over the Yellow Sea

Sea fog is typically formed and developed under a set of favorable environmental conditions, which are associated with the station pressure changes, sea level pressure, winds, temperature, water vapor supply, and sea surface temperature. Understanding of these environmental factors during the evolution of a sea fog episode is crucial for forecasting the occurrence and severity of sea fogs over the ocean and adjacent coastal areas. In this study, the large-scale environment variability of six fog events over the Yellow Sea was investigated. It was realized in the present study that the northwest Pacific Ocean high (NPH) is vital to fog formation over the Yellow Sea. In our study, six fog cases can be basically divided into two types: (1) pressure-weakening type, (2) pressure-strengthening type. The former type happened in spring and the latter type in summer. Prevailing southerly winds, accompanied with the well-positioned NPH, may supply a large amount of warm water vapor for the fog formation and maintenance. The intensity of the air temperature inversion is stronger in summer cases than that in spring ones. The wind direction change from south to north and the unstable lower atmosphere may lead to fog’s dissipation. This study may provide a comprehensive understanding of sea fog’s onset, maintenance, and dissipation over the Yellow Sea.     

A Comparison Study Between Spring and Summer Fogs in the Yellow Sea-Observations and Mechanisms

New observations from buoys and soundings reveal the discrepancies in air–sea interface and in vertical structures between spring (April to May) and summer (July) fogs in the Yellow Sea. Spring fogs are shallow with a robust temperature inversion, dry layer and cold phase (surface air temperature or SAT is lower than sea surface temperature or SST); summer fogs are deep with weaker stability, indistinct fog top and warm phase (SAT?>?SST). Along with numerical simulations, conceptual models for the mechanisms of temperature inversion are suggested. The land–sea contrast is responsible for the robust temperature inversion in spring, and the deep southerlies derived from the east Asian summer monsoon and the adiabatic sinking from the western Pacific subtropical high contributes to the weaker inversion in summer. The dry layer above the sea fog top intensifies the longwave radiative cooling effect to lead to the cold phase in spring fogs. The radiative cooling is weaker in summer fogs resulting in SAT?>?SST.     

基于居民地分布的震害快速评估方法

0引言地震灾害总是伴随着巨大的生命和财产损失。随着城市化的加速发展,人口不断地由农村向城镇地区集中,使地震灾害造成的损失有增大的趋势(陈等,2001、1997)。地震发生后,快速地做出地震灾害损失评估,对地震应急救援具有重要指导意义。如何快速有效地进行地震灾害损失评估,国内外地震专家做了深入的讨论,开展了大量的城市震害预测和震灾快速评估研究,建立了一系列基于城市大规模单体及群体调查的地震应急灾害损失评估模型。但是,基于城市的震害研究投入大,系统数据不易更新,难以在全国范围内大规模开展。破坏性地震波及半径通常要达到10…     

An examination of summer precipitation over Asia based on TRMM/TMI

A 6-year dataset of summer monthly mean precipitation derived from Tropical Precipitation Measure-ment Mission (TRMM)-Microwave Imager (TMI) was used to delineate the spatial distribution patterns of precipitation throughout Asian areas, which indicates that there are three rainfall centers located at the northern coast of the Bay of Bengal, the South China Sea and the western equatorial Pacific Warm Pool, respectively. Based upon the analysis of horizontal distribution, the capability of TMI for characterizing terrestrial and maritime precipitation has been evaluated and compared with Global Precipitation Climatology Project (GPCP) dataset. It was found that TMI and GPCP are well consistent with each other, while a few significant differences occur at several regions over land. By investigating rainfall esti-mates over six specific locations in Asia, a systematic underestimation of TMI was demonstrated, which could be explained by the inherent deficiency within TMI terrestrial algorithm relying on scat-tering signal from ice particles in a precipitation system. A further analysis shows that the highly in-homogeneous distribution of rain gauges employed by GPCP contributes a great deal to the significant discrepancy between GPCP and TMI, especially over regions surrounding the Tibetan Plateau where rain gauges are quite scarce.