新疆喀什两次超级单体致雹风暴特征对比分析

利用常规气象观测资料,对2011年发生在喀什地区夏季罕见的两次强度不同的超级单体致雹风暴进行了特征分析。结果表明：不稳定层结、冷空气活动频繁和抬升触发条件是喀什地区产生强对流天气的共同环境场特征;充足的水汽及强的垂直风切变更有利于喀什地区深厚湿对流活动的产生;初夏雹暴的发生、发展存在1支异常水汽输送,输送量10.9×10⁸ t;而盛夏雹暴存在3支异常水汽输送,输入量11.4×10⁸ t;θ_e陡立区与冰雹落区对应较好,垂直涡度与倾斜涡度发展旺盛,是造成大范围雹暴的主要原因。强回波高悬,低层入流显著、低层反射率因子高梯度区是强对流天气共同的回波特征;初夏雹暴为弓形回波、中-γ尺度;盛夏雹暴为强超级单体、中-β尺度;回波伸展高度越高、低层入流越显著、垂直风切变越强的对流系统产生的天气越激烈,易产生大雹。     

Contact angles in CO2-water-coal systems at elevated pressures

Injection of carbon dioxide into coal seams is considered to be a potential method for its sequestration away from the atmosphere. However, water present in coals may retard injection: especially if carbon dioxide does not wet the coal as well as water. Thus contact angles in the coal-water-CO₂ system were measured using CO₂ bubbles in water/coal systems at 40 °C and pressures up to 15 MPa using five bituminous coals. At low pressures, in this CO₂/water/coal system, receding contact angles for the coals ranged between 80° to 100°; except for one coal that had both high ash yield and low rank, with a contact angle of 115°, indicating that it was hydrophilic. With increasing pressure, the receding contact angles for the different coals decreased, indicating that they became more CO₂-wetting. The relationship between contact angle and pressure was approximately linear. For low ash or high rank coals, at high pressure the contact angle was reduced to 30-50°, indicating the coals became strongly CO₂-wetting; that is CO₂ fluids will spontaneously penetrate these wet coals. In the case of the coal that was both high ash and hydrophilic, the contact angle did not drop to 90° even at the highest pressures used. These results suggest that CO₂ will not be efficiently adsorbed by all wet coals equally well, even at high pressure. It was found that at high pressures (> 2 MPa) the rate of penetration of carbon dioxide into the coals increased rapidly with decreasing contact angle, independently of pressure. Injecting CO₂ into wet coals that have both low rank and high ash will not trap CO₂ as well as injecting it into high rank or low ash coals.     

The connection between Labrador Sea buoyancy loss, deep western boundary current strength, and Gulf Stream path in an ocean circulation model

The sensitivity of the North Atlantic gyre circulation to high latitude buoyancy forcing is explored in a global, non-eddy resolving ocean general circulation model. Increased buoyancy forcing strengthens the deep western boundary current, the northern recirculation gyre, and the North Atlantic Current, which leads to a more realistic Gulf Stream path. High latitude density fluxes and surface water mass transformation are strongly dependent on the choice of sea ice and salinity restoring boundary conditions. Coupling the ocean model to a prognostic sea ice model results in much greater buoyancy loss in the Labrador Sea compared to simulations in which the ocean is forced by prescribed sea ice boundary conditions. A comparison of bulk flux forced hindcast simulations which differ only in their sea ice and salinity restoring forcings reveals the effects of a mixed thermohaline boundary condition transport feedback whereby small, positive temperature and salinity anomalies in subpolar regions are amplified when the gyre spins up as a result of increased buoyancy loss and convection. The primary buoyancy flux effects of the sea ice which cause the simulations to diverge are ice melt, which is less physical in the diagnostic sea ice model, and insulation of the ocean, which is less physical with the prognostic sea ice model. Increased salinity restoring ensures a more realistic net winter buoyancy loss in the Labrador Sea, but it is found that improvements in the Gulf Stream simulation can only be achieved with the excessive buoyancy loss associated with weak salinity restoring.     

淄博市大武水源地地下水水位总体预测

本文采用水均衡法对淄博市大武水源地地下水位变动进行研究，并对降水量与人渗补给量的关系以及平均给水度随地下水位的变化关系进行了分析。通过历史资料的验证，表明本文所建立的水均衡模型对于地下水位变动的预测是可靠的，而且简单可行，随后根据不同的地下水开采量等对未来地下水位的变动趋势进行了预测。     

新疆1999-2009年水足迹计算与分析

利用统计资料,结合水足迹模型和区域水足迹评价方法,对新疆1999-2009年的水足迹及相关指标进行了计算和分析。研究表明：（1）新疆1999-2004年总水足迹呈上升趋势,2004- 2009年略有下降趋势。水资源集约利用度呈增长趋势,说明新疆水资源利用效率有所提高;（2）新疆居民对粮食、肉类等虚拟水含量较大的农产品需求较大,适当减少虚拟水含量较高的产品消费,提倡虚拟水含量较低的产品消费,可减少虚拟水量的消耗;（3）新疆在虚拟水贸易中是水资源输出地,且输出量在不断增大,给新疆本地的水资源利用带来巨大的压力;（4）新疆水资源压力逐年增加,解决水资源短缺问题不能局限于本地实体水资源的高效利用,还可通过虚拟水贸易从水源丰富地区购买高耗水的本地发展所需的相关消费品,实现水资源总体可持续利用。改变消费模式,调整虚拟水战略结构成为缓解新疆水资源短缺的一种可能途径,由于数据限制,水足迹研究有待进一步细化,但是一种可用于探讨干旱区水资源可持续利用的方法。     

Morphological assessment of reconstructed lowland streams in the Netherlands

Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Re-meandering is the common practice in restoring these lowland streams. Three reconstructed streams were monitored during the initial two years after construction of a new channel. The monitoring program included morphological surveys, sediment sampling, habitat pattern surveys, and discharge and water level measurements. Adjustments of the longitudinal bed profile formed the main morphological response. These adjustments were most likely caused by a lack of longitudinal connectivity of the streams as a whole, interrupting transport of sediment at locations of weirs and culverts. Bank erosion was observed only in a limited number of channel bends, and was often related to floodplain heterogeneity. Longitudinal channel bed adjustments and bank erosion were mainly caused by exogenous influences. In channel bends, the cross-sectional shape transformed from trapezoidal to the typical asymmetrical shape as found in meandering rivers. This behaviour can be attributed to an autogenous response to the prevailing flow conditions. Due to the prevailing fine sediment characteristics, bed material is readily set in motion and is being transported during the entire year. The existing design principles fail to address the initial morphological development after reconstruction. An evaluation of pre-set targets to realise water depth and flow velocity ranges shows the current procedures to be deficient. Based on this unfavourable evaluation, and the two-dimensional nature of habitat patterns needed to improve the conditions for stream organisms, we recommend to predict morphological developments as part of the design procedures for lowland stream restoration in the Netherlands.     

地基GPS气象学研究的主要问题及最新进展

目前大多数映射函数在低高度角时精度都比较差，发展适应低高度角的映射函数，提高低高度角观测值的利用率，研究大气的水平梯度是目前地基GPS气象学的主要研究任务，发展随时空变化的动态映射函数也是国际上的一个主要研究问题。由于PWV不能提供水汽分布的三维信息，求定GPS信号斜路径方向上的水汽SWV，以及利用SWV层析大气的垂直结构是目前国际上 GPS气象学的研究前沿。文中总结了目前国际上SWV的求定及层析水汽三维结构的主要方法，及存在的问题。把GPS探测的水汽同化到数值天气预报中，以提高数值预报的能力是GPS气象学研究的目的，作者介绍了目前水汽在数值预报模型中的同化情况。另外还回顾了利用GPS观测结果进行全球气候变化和大气折射环境研究的进展。     

考洲洋海域水质季节变化及评价方法初步研究

文章于2018年1月（冬季）、4月（春季）、7月（夏季）、10月（秋季）对我国考洲洋海域海水中的溶解氧（DO）、化学需氧量（COD）、无机氮（DIN）、活性磷酸盐（DIP）4个主要海水水质因子进行了综合调查。结果表明,4个水质因子DIP、DIN、COD、DO的平均浓度由高到低的季节变化分别为：冬季（0.058 mg/L）、春季（0.046 mg/L）、夏季（0.009 mg/L）、秋季（0.006 mg/L）;冬季（0.465 mg/L）、春季（0.171 mg/L）、夏季（0.064 mg/L）、秋季（0.040 mg/L）;夏季（1.57 mg/L）、冬季（1.26 mg/L）、秋季（1.22 mg/L）、春季（0.89 mg/L）;冬季（11.70 mg/L）、夏季（7.41 mg/L）、秋季（7.36 mg/L）、春季（7.18 mg/L）。评价结果显示,春季和冬季主要超标因子为DIP和DIN,夏季超标因子为DIP,秋季水质因子均满足要求。同时,本研究利用单因子标准指数法、富营养化指数法和有机污染评价指数法对考洲洋地区水质状况进行评价并对其进行初步比较和分析,结果表明,3种方法在季节性变化上的评价结果基本一致（由高到低均为:冬季、春季、夏季、秋季）,然而,同一季节不同评价方法的超标站位比例不同（单因子指数法:冬季占100%,春季占80%,夏季占10%,秋季则无;富营养化指数法:冬季占90%,春季占70%,夏季和秋季均为无;有机污染指数评价法:冬季和春季均占80%,夏季和秋季均为无）,比较分析表明,3种评价方法具有不同的评价作用和适用性。     

夏季黄海冷水团海域的丙烯酸分布与海洋环境因子和叶绿素a变化之间的关系

海水中主要含硫化合物β-二甲基巯基丙酸内盐(DMSP)降解可产生丙烯酸(AA)和活性气体二甲基硫(DMS)。2011年8月对黄海冷水团海域的AA及相关参量的分布特征进行了研究。结果表明,该海域表层海水中AA的浓度为0~0.208μmol/L,平均值为(0.081±0.075)μmol/L。AA的高值区出现在海域的东南部,可能是受到长江冲淡水的影响。AA的浓度总体上呈现出由南到北递增的趋势,与Chl-a较为一致,表明该海域的AA主要是由DMSP裂解产生的。表层海水中AA与温度表现出明显的负相关性。AA的垂直分布表现为:中层底层表层,这可能是产生AA的浮游植物与消耗AA的细菌共同作用的结果。海域中AA浓度与DMSP或DMS无明显的相关性。AA浓度远高于DMS,AA/DMS平均为106∶1,初步估算出DMSP降解产生的AA约为66.5%。AA/Chl-a平均为126.6 mmol/g,比DMSP/Chl-a高1个数量级,比DMS/Chl-a高2个数量级。     

2013年南疆2场罕见暴雨落区和强度的对比分析

2013年5月26～28日和6月15～18日南疆连续出现了2场罕见的暴雨过程,利用常规地面和高空探测资料、NCEP/NCAR每日4时次 1°×1°再分析资料和欧洲ECWMF 0.25°×0.25°细网格数值预报产品,对比分析了这2场暴雨的落区和强度差异的成因。2场暴雨均在有利的环流背景下产生,较强暴雨的高空环流经向度更大、中亚低槽与北支槽打通并南伸更南,低层700hPa以下水汽输送较中高层更为重要,日常预报更应注重低层的水汽输入。对比暴雨强度,低层水汽输送越强(更多水汽路径、更多边界的水汽输入、更强水汽通量和水汽输入量)、低层水汽输送时间越长、低层切变线持续时间长且伸展至中高层,暴雨强度均可能更强。中尺度切变线和涌线在暴雨落区预报中具有一定的指示意义。