Improving the extreme rainfall forecast of Typhoon Morakot (2009) by assimilating radar data from Taiwan Island and mainland China

This study examined the impact of an improved initial field through assimilating ground-based radar data from mainland China and Taiwan Island to simulate the long-lasting and extreme rainfall caused by Morakot (2009). The vortex location and the subsequent track analyzed through the radial velocity data assimilation (VDA) are generally consistent with the best track. The initial humidity within the radar detecting region and Morakot’s northward translation speed can be significantly improved by the radar reflectivity data assimilation (ZDA). As a result, the heavy rainfall on both sides of Taiwan Strait can be reproduced with the joint application of VDA and ZDA. Based on sensitivity experiments, it was found that, without ZDA, the simulated storm underwent an unrealistic inward contraction after 12-h integration, due to underestimation of humidity in the global reanalysis, leading to underestimation of rainfall amount and coverage. Without the vortex relocation via VDA, the moister (drier) initial field with (without) ZDA will produce a more southward (northward) track, so that the rainfall location on both sides of Taiwan Strait will be affected. It was further found that the improvement in the humidity field of Morakot is mainly due to assimilation of high-value reflectivity (strong convection) observed by the radars in Taiwan Island, especially at Kenting station. By analysis of parcel trajectories and calculation of water vapor flux divergence, it was also found that the improved typhoon circulation through assimilating radar data can draw more water vapor from the environment during the subsequent simulation, eventually contributing to the extreme rainfall on both sides of Taiwan Strait.     

西藏冈底斯甲马和南木矿床流体包裹体SR-XRF研究

对西藏冈底斯铜多金属成矿带中甲马和南木矿床的流体包裹体开展了系统的同步辐射X射线荧光(SR-XRF)微束原位无损分析,结果显示:甲马矿床流体包裹体中高Cr、Pb,低Ni、Fe,且存在高于地壳丰度的Pt、Ir含量异常;南木矿床流体包裹体中高Cr、Cu、Pb,低Ni、Fe、Zn,晚期有Au富集,Cu倾向于在高盐度流体中富集.甲马和南木两矿床成矿流体中元素的原始地幔标准化模式与两矿区的成矿斑岩大体类似,显示出两矿床与区内斑岩在物质来源上具有亲缘性,幔源和壳源物质共同参与了成矿.但Cr含量的差异也显示出,尽管成矿流体与斑岩岩浆可能都起源于深部,但二者在演化上是平行的.对于甲马矿床的成因,流体包裹体SR-XRF原位组成分析以及显微测温结果不支持喷流沉积成因观点.     

基于MODIS和TRMM数据的黄土高原农业干旱监测

农业干旱对农业生产影响最为严重,基于站点观测数据的干旱指数不能准确监测区域尺度的农业干旱特征。因此,利用2003—2015年MODIS地表温度(LST)、植被指数(NDVI)和TRMM降水(3B43)数据以及1960—2015年黄土高原地区及周边92个气象站点的月均温和月降水量数据,构建了综合遥感干旱监测模型规模干旱条件指数(Scale Drought Condition Index,SDCI),对黄土高原地区农用地生长季(4～10月)旱情的时空分布特征进行研究,结果表明:黄土高原地区农用地生长季多年平均干旱状态为中度干旱,干旱程度在空间上表现为西北部较严重,东南部较轻。2003—2015年黄土高原地区旱情年际变化总体呈波动减轻趋势,2003—2007年旱情越来越严重,2007—2014年旱情波动减轻,2014—2015年旱情有所加重。黄土高原地区旱情年内变化表现4～8月持续减轻,8～10月持续加重,干旱程度具体表现为4月、5月、6月和10月呈中度干旱,7月、8月和9月呈轻度干旱。研究表明利用多源遥感数据构建的具有适当权重的SDCI可以有效监测黄土高原地区作物生长季的干旱状况。     

Combining the SWAT model with sequential uncertainty fitting algorithm for streamflow prediction and uncertainty analysis for the Lake Dianchi Basin,China

Streams play an important role in linking the land with lakes. Nutrients released from agricultural or urban sources flow via streams to lakes, causing water quality deterioration and eutrophication. Therefore, accurate simulation of streamflow is helpful for water quality improvement in lake basins. Lake Dianchi has been listed in the ‘Three Important Lakes Restoration Act’ in China, and the degradation of its water quality has been of great concern since the 1980s. To assist environmental decision making, it is important to assess and predict hydrological processes at the basin scale. This study evaluated the performance of the soil and water assessment tool (SWAT) and the feasibility of using this model as a decision support tool for predicting streamflow in the Lake Dianchi Basin. The model was calibrated and validated using monthly observed streamflow values at three flow stations within the Lake Dianchi Basin through application of the sequential uncertainty fitting algorithm (SUFI‐2). The results of the autocalibration method for calibrating and the prediction uncertainty from different sources were also examined. Together, the p‐factor (the percentage of measured data bracketed by 95% prediction of uncertainty, or 95PPU) and the r‐factor (the average thickness of the 95PPU band divided by the standard deviation of the measured data) indicated the strength of the calibration and uncertainty analysis. The results showed that the SUFI‐2 algorithm performed better than the autocalibration method. Comparison of the SUFI‐2 algorithm and autocalibration results showed that some snowmelt factors were sensitive to model output upstream at the Panlongjiang flow station. The 95PPU captured more than 70% of the observed streamflow at the three flow stations. The corresponding p‐factors and r‐factors suggested that some flow stations had relatively large uncertainty, especially in the prediction of some peak flows. Although uncertainty existed, statistical criteria including R² and Nash–Sutcliffe efficiency were reasonably determined. The model produced a useful result and can be used for further applications. Copyright © 2012 John Wiley & Sons, Ltd.     

随机反演在陆丰13-1油田储层预测中的应用

这里以陆丰13-1油田为例,研究发现井上波阻抗曲线并不能有效区分砂岩储层和泥岩非储层,故对孔隙度数据体进行了反演.首先对井上孔隙度曲线进行直方图统计分析,变差函数分析及孔隙度和波阻抗的相关性分析,然后用高斯模拟加模拟退火的随机反演方法对研究区进行了孔隙度体的反演.经反演发现,较其它反演方法孔隙度体反演剖面分辨率有了很大提高,对薄砂体也能很好地识别,且与井上吻合较好,能很好地刻画出砂体的横向变化情况,平面上砂体的展布也符合该区的沉积相分布.     

西藏那曲县尤卡朗铅银矿床控矿条件与矿化分布规律

尤卡朗铅银矿床处于尤卡朗 - 同德铅银多金属成矿带中部,纳木错-嘉黎断裂带北侧.主要控矿条件包括基底地层和构造.主断裂派生的次级断裂构造控制了矿床的定位和空间展布,侏罗纪马里组地层是重要矿源层.后期热事件使成矿元素富集,并在压力驱使下沿构造裂隙上升,在围岩有利地段充填交代形成矿床.根据矿体在空间上的展布和变化规律及异常特征,对矿区边部和深部隐伏矿体进行了预测.     

奥陶系宝塔灰岩网纹构造成因研究进展及新发现

综述了扬子地区分布广泛的奥陶系宝塔灰岩网纹构造成因的研究进展,整合了多位学者的主要观点及认识,结合四川旺苍唐家河等地奥陶系剖面的考察与镜下薄片观察,对网纹构造及其成因进行了深入研究并提出未来研究方向的思考与建议。学界目前普遍认为这种网纹构造并非暴露干裂成因,生物遗迹、海底硬地、准同生变形构造等成因解释也缺乏足够的证据支持,但关于水下胶缩、成岩作用以及构造作用等解释仍在热烈讨论中;对四川广元旺苍唐家河剖面宝塔灰岩的野外考察过程中发现了一些新的现象,比如在灰色宝塔灰岩中观察到了非沥青充填的“黑色细纹”,网纹构造的形态、泥质含量等也随沉积旋回而呈现出规律性变化。进一步研究这些新的现象或许能为后期确定网纹构造的成因提供新的证据。     

海洋气象条件变化对青岛平流雾过程的影响分析

利用风廓线资料、探空资料和地面气象观测资料对青岛夏季的一次平流雾过程进行了分析,探讨了雾的演变与气象条件的关系。研究表明:雾的强度和厚度与风的垂直结构密切相关,风向为稳定的东南风,90%以上的相对湿度层有一定厚度时,3 m/s以内的风速层内容易成雾,雾顶高度在240~530 m之间。雾顶可以在逆温层底,也可能低于逆温层底。逆温层抬升有利于雾层向上发展,突破混合层高度。稳定的向岸风有利于海风的形成,造成比湿持续增加和大气中粗粒子增多,能见度下降和雾的出现。     

1215号“布拉万”台风暴雨及降水非对称性分布的成因分析

利用中尺度非静力模式WRF对2012年第15号台风“布拉万”在中国东北地区造成的暴雨过程进行了数值模拟,结合观测资料对模拟结果进行了验证,利用模式输出的高分辨率资料,对“布拉万”台风造成的强降水及其非对称性分布的成因进行了诊断分析。结果表明,模式很好地再现了台风登陆过程中的路径、强度变化和降水分布,受中纬度西风槽带来的干冷空气影响,“布拉万”台风登陆后的降水和环流结构具有明显的不对称性,降水主要集中在台风中心西北侧的能量锋区附近。水汽散度通量和水汽螺旋度能够较好地描述强降水过程的发生、发展及其非对称性分布的时空特征,在强降水区,水汽散度通量表现为正值强信号,而水汽螺旋度表现为负值强信号,在非降水区和弱降水区,两者均表现为弱信号。等熵位涡分析显示,对流不稳定只是此次台风暴雨前期和初始阶段的不稳定条件,而湿位涡(MPV)的湿斜压项(MPV₂)则是暴雨增强和出现非对称性分布的主要机制。在暴雨形成过程中,由于冷空气侵入造成了在台风环流西北侧湿等熵面的陡立倾斜和水平风垂直切变的增强,导致了气旋性涡度的显著增强,气旋性涡度增强造成的强烈上升运动将降水区东南侧输送过来的暖湿空气向上输送,从而导致了暴雨的发生,这其中条件性对称不稳定是降水得以加强的一种重要不稳定机制。     

近岸二类水体生物光学模型参数优化

为了优化生物光学模型中的悬浮物后向散射模型系数（b^_bx）和双向反射因子（f/Q）,基于珠江口、韩江河口、徐闻珊瑚礁保护区实测数据（遥感反射率、叶绿素a质量浓度、悬浮物质量浓度、CDOM吸收系数）,采用模拟退火算法同时优化了b_bx以及f/Q（N＝43）,并开发了生物光学正演模型（N＝22）。文章优化的f/Q为0.104 9,悬浮物在参考波长531 nm处后向散射系数b_bx为0.268×[TSS]^0.295。通过输入实测的水质数据模拟出531 nm处的遥感反射率,并外推到其他波段（412、443、490、551、667 nm）。模拟得到的531 nm处遥感反射率与实测值的均方根误差RMSE＝0.000 8,N＝22,除了模拟的667 nm处遥感反射率误差较大外（RMSE＝0.003 6,N＝22）,其他波段都具有较好的精度（RMSE＜0.002 3）。结果表明,该研究区与其他研究区（如黄、东海）的bbx和f/Q不一致,这2个参数需要根据研究区的数据进行优化。验证结果说明迭代优化的b_bx以及f/Q能够适用于广东近岸河口生物光学参数模拟。