近48年中国沙尘暴的时空分布特征及其变化

1　资料与说明沙尘暴资料集和气温、降水及风速等资料由中国气象局气象信息中心气象资料室提供 ,包括 71 8个站 1 954～ 2 0 0 1年的逐月和年数据。由于建站时间不一及台站任务变更等多种原因 ,各序列的长度不完全一致。经统计 ,连续 48年或连续 42年有资料的站点分别为 3 4 4和 584个。在进行空间分布特征分析时 ,兼顾到站点的空间覆盖度和序列长度的一致性 ,故以 1 960～ 2 0 0 1年作为求取平均值的标准时段。但由于青藏高原气象测站数量较少且建站时间偏晚 ,为了尽可能提高资料密度 ,参照 3 0年这一统计气候平均态的一般标准 ,保留了长度…     

Evaluating climate variability and pumping effects in statistical analyses

As development of ground water resources reaches the limits of sustainability, it is likely that even small changes in inflow, outflow, or storage will have economic or environmental consequences. Anthropogenic impacts of concern may be on the scale of natural variability, making it difficult to distinguish between the two. Under these circumstances, we believe that it is important to account for effects from both ground water development and climate variability. We use several statistical methods, including trend analysis, cluster analysis, and time series analysis with seasonal decomposition, to identify climate and anthropogenic effects in regional ground water levels and spring discharge in southern Nevada. We discuss the parameterization of climate and suggest that the relative importance of various measures of climate provides information about the aquifer system response to climate. In our system, which may be characteristic of much of the arid southwestern United States, ground water levels are much more responsive to wet years than to dry years, based on the importance of selected climate parameters in the regression. Using cluster analysis and time series seasonal decomposition, we relate differences in amplitude and phase in the seasonal signal to two major forcings—climate and pumping—and distinguish between a regional recharge response to an extremely wet year and a seasonal pumping/evapotranspiration response that decays with distance from the pumping center. The observed spring discharge data support our hypothesis that regional spring discharge, particularly at higher elevation springs, is sensitive to relatively small ground water level changes.     

The Distances of Subclusters in the Virgo Area

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＶｉｒｇｏｃｌｕｓｔｅｒｏｆｇａｌａｘｉｅｓｉｓｔｈｅｎｅａｒｅｓｔｙｏｕｎｇｒｉｃｈｃｌｕｓｔｅｒａｎｄｐｌａｙｓａｓａｃｒｉｔｉｃａｌｒｏｌｅｎｏｔｏｎｌｙｉｎｔｈｅｆｏｒｍａｔｉｏｎａｎｄｅｖｏｌｕｔｉｏｎｏｆｇａｌａｘｙｃｌｕｓｔｅｒ ,ｂｕｔａｌｓｏｉｎｃａｌｉｂｒａｔｉｎｇｔｈｅｃｏｓｍｏｌｏｇｉｃａｌｄｉｓ ｔａｎｔｓｃａｌｅ(ｖａｎｄｅｎＢｅｒｇｈ ,1 994) .Ｔｈｅｒｅａｒｅａｌｏｔｏｆｒｅｓｅａｒｃｈｗｏｒｋｓｔｈａｔｆｏｃｕｓｏｎｔｈｅｄｅｔｅｒｍ…     

海底流体排出及甲烷水合物BSR形成机理

在大陆边缘海底之下几百米深度处普遍观察到BSR,这些沉积物经历近的构造固红或快速堆积,相信BSR与稳定的甲烷水合物（笼形物）的最深部位对应,我们提出了下模式,BSR水合物的形成是在运移着的孔隙流体进水合物稳定域时,由向上运移的孔隙流体排出甲烷,在这个模式里,大多数甲烷产生于水合物稳定带之下,但此深度不足以充分生热,甲烷初始属生物成因,该模式要求从孔隙流体中排出已分解的甲烷,或随孔隙流体向上搬运已散布的游离气,模式解释证据,水合物在稳定域底界处浓聚,大量的甲烷源包含在水合物内,BSRs仅在特殊环境下出现,在深积物正常沉积体制下,不会向上强裂排出流体进入不合物稳定域,,所以BSRs不普遍,由于俯冲带增生楔处构造加厚,荷载增加,引致流体向上排出,该地区快速沉积未固结成岩,这些地区水合物BSRs常见,当孔隙流体进入水合物流体＋水合物与流体域之间的严格边界,然而,需要形成水合物的甲烷数量源自深海钻井有关孔隙流体中烷浓度的有限资料暗示,从上升流体中有效的排出甲烷,可以包含比所需产生游离气的数量少,在大多数流体排出体制,流体向上运移至海底的数量足够连续排出过剩的氯化物及水合物形成时同位素分离的残余物,因此,当观察钻孔资料,没有大量氯化物或同位素异常残留在孔隙流体内,甲烷浓度与稳定域上或下的孔隙流体内CO2量之差别,可以对早期沉积物成岩反应有明显的影响。     

《对2006 IPCC国家温室气体清单指南的2013增补:湿地》的解析

为了填补《2006 IPCC国家温室气体清单指南》有关湿地的温室气体排放与吸收清单编制方法学指南的空缺,IPCC于2014年2月底发布了《对2006IPCC国家温室气体清单指南的2013增补:湿地》。该指南在考虑人类活动影响以及对湿地定义进行重新梳理的基础上,给出了湿地排干、还湿的温室气体排放与吸收的估算方法;同时,也增补了滨海湿地、用于污水处理人工湿地的温室气体排放与吸收的估算方法。该指南的发布为清单编制者估算人类活动所导致的湿地温室气体排放与吸收提供了较全面的方法学。当然,受到科学认识水平与文献的限制,该指南在随排水流失的颗粒有机碳损失量的估算、随还湿来自于湿地外其他生态系统有机碳的进入所产生排放量估算等方面存在着需进一步完善的内容。     

中白垩世低纬度地区海面温度和浮游有孔虫的演化

陆地和海洋大范围的古气候指标说明了中至晚白垩世早期（阿尔必—科尼亚阶）是过去２００Ｍａ中地球历史上最温暖的时期（全球平均表层水温比目前高６～１４℃）。然而,通常只基于低反照率和高气压（Ｐｃｏ２）的气候模型模拟产生了较高的赤道海洋表层水温（ＳＳＴｓ）,...     

The movement of oil under non-breaking waves

The combined effects of wave kinematics, turbulent diffusion, and buoyancy on the transport of oil droplets at sea were investigated in this work using random walk techniques in a Monte Carlo framework. Six hundred oil particles were placed at the water surface and tracked for 500 wave periods. A dimensionless formulation was presented that allowed reporting distances in terms of the wave length and times in terms of the wave period. Stokes' drift was, expectedly, the major mechanism for horizontal transport. It was also found that plumes that have large terminal rise velocities move faster forward but spread less than those that have small terminal rise velocities. The increase in wave slope (or wave steepness) caused an increase in transport and spreading of the plume. Our results supported treating the oil as completely mixed vertically in a layer near the surface. In the horizontal direction, buoyant plumes had spreading coefficients that are essentially constant after about 200 wave periods. But neutrally buoyant plumes had horizontal spreading coefficients that increased with time (for the simulation time of 500 wave periods). Techniques for generalizing the results for a wide range of wave parameters were presented.     

Comparing methods and sediment contaminant indicators for determining produced water fate in a Louisiana estuary

Produced water is a high salinity by-product resulting from oil and gas production. Disposal methods include surface water discharge. The current field method used to determine its fate in estuarine systems involves extending a compass oriented transect (COT) from the point source discharge--a method designed for a uniformly dispersing effluent discharged into a uniform offshore environment that may be inappropriate for the hydrologic and geomorphologic complexities found in estuarine systems. Prior research established the viability of the salinity stratification transect (SST) method. Both COT and SST methods were used in a small open bay to determine which more accurately detected effluent dispersion. Determination was based on sediment contaminant indicators (SCIs), including interstitial salinity, hydrocarbons, metals, and radium concentrations. Additionally, SCIs were evaluated for their ability to serve as indicators of effluent dispersion. The data revealed that SST stations exhibited higher contaminant concentrations and that this approach was more accurate in tracking the produced water plume. The data also suggested that SCIs varied in their ability to serve as indicators. Good indicators included interstitial salinity, total targeted aromatic hydrocarbons substantiated with a modified fossil fuel pollution index value, certain metals, and radium-228.