MICROPHYSICAL CHARACTERISTICS OF THE RAINDROP SIZE DISTRIBUTION IN TYPHOON MORAKOT (2009)

Microphysical characteristics of the raindrop size distribution(RSD)in Typhoon Morakot(2009) have been studied through the PARSIVEL disdrometer measurements at one site in Fujian province,China during the passage of the storm from 7 to 10 August 2009.The time evolution of the RSD reveals different segments of the storm.Significant difference was observed in the microphysical characteristics between the outer rainband and the eyewall;the eyewall precipitation had a broader size distribution(a smaller slope) than the outer rainband and eye region.The outer rainband and the eye region produced stratiform rains while the eyewall precipitation was convective or mixed stratiform-convective.The RSD was typically characterized by a single peak distribution and well represented by the gamma distribution.The relations between the shape(μ)and slope(Λ)of the gamma distribution and between the reflectivity(Z)and rainfall rate(R)have been investigated.Based on the NW-Dm relationships,we suggest that the stratiform rain for the outer rainband and the eye region was formed by the melting of graupel or rimed ice particles,which likely originated from the eyewall clouds.     

VALIDATION OF NEAR-SURFACE WINDS OBTAINED BY A HYBRID WRF/CALMET MODELING SYSTEM OVER A COASTAL ISLAND WITH COMPLEX TERRAIN

The results from a hybrid approach that combines a mesoscale meteorological model with a diagnostic model to produce high-resolution wind fields in complex coastal topography are evaluated.The diagnostic wind model(California Meteorological Model,CALMET) with 100-m horizontal spacing was driven with outputs from the Weather Research and Forecasting(WRF) model to obtain near-surface winds for the 1-year period from 12 September 2003 to 11 September 2004.Results were compared with wind observations at four sites.Traditional statistical scores,including correlation coefficients,standard deviations(SDs) and mean absolute errors(MAEs),indicate that the wind estimates from the WRF/CALMET modeling system are produced reasonably well.The correlation coefficients are relatively large,ranging from 0.5 to 0.7 for the zonal wind component and from 0.75 to 0.85 for the meridional wind component.MAEs for wind speed range from 1.5 to 2.0 m s-1 at 10 meters above ground level(AGL) and from 2.0 to 2.5 m s-1 at 60 m AGL.MAEs for wind direction range from 30 to 40 degrees at both levels.A spectral decomposition of the time series of wind speed shows positive impacts of CALMET in improving the mesoscale winds.Moreover,combining the CALMET model with WRF significantly improves the spatial variability of the simulated wind fields.It can be concluded that the WRF/CALMET modeling system is capable of providing a detailed near-surface wind field,but the physics in the diagnostic CALMET model needs to be further improved.     

区域风能资源评价分析的动力降尺度研究

不同于以往的统计风能评估方法,本研究将动力降尺度方法应用到江苏省的风能评价分析中。利用NCEP/NCAR再分析资料与江苏省65个地面气象观测站1971～2000年的观测资料,建立了动力降尺度区域气候模式MM5V3的初始场和边界条件,用较高分辨率（水平分辨率为5 km）评估了江苏省60 m高度的风能分布,分析了动力降尺度方法在区域风能资源评估中的有效应用。结果表明,江苏省风能资源由东部沿海向西部内陆递减,以西连岛为代表的东部沿海风能资源最丰富,其次为长江三角洲地区,太湖、洪泽湖及高邮湖地区的风能资源也比较丰富,徐州市与南京市的风能资源最贫乏。分析表明,动力降尺度方法能够用较高分辨率模拟局地环流和地面风的主要分布特征,可以作为区域风能资源评价分析的有效手段。     

Chaba (0417) 台风变性前后热力结构特征

运用美国NOAA-15极轨气象卫星高分辨率的AMSU探测资料, 结合NCEP/NCAR再分析资料和GMS-5气象卫星红外云顶亮温(TBB)资料, 对2004年Chaba(0417)台风(TC)变性前后的热力结构特征进行分析。发现变性前TC暖核结构呈对称分布, 在高空存在一强暖心; 变性后原TC对称暖心结构消失, 存在于温带气旋上空的相对暖区呈现出倾斜的非对称分布, 在高、低层各形成一弱的暖区中心, 锋面的斜压特性显著。通过热力结构对比, 进一步揭示出TC在向高纬度方向移动时, 与中纬度系统相互作用发生变性, 实质上是两个相继过程, 即热带气旋的消亡和温带气旋的生成发展。TC西侧高空干冷空气的入侵下沉, 破坏了其发展所需的水汽条件, 造成TC对称暖核结构的削弱和损毁。与此同时, 在TC残留区域, 由于空气较暖且存在气旋式环流, 暖空气在东侧呈气旋式上升, 与西侧高空入侵下沉的干冷空气形成偶极, TC暖气团与冷空气相交发展形成斜压的结果, 则为温带气旋的生成和发展创造了有利条件。     

海洋飞沫对热带气旋影响的数值试验

将最新版的Andreas海洋飞沫通量参数化方案与中尺度大气模式MM5V3耦合,对0514号热带气旋Nabi进行数值模拟,探讨海洋飞沫蒸发对热带气旋发展和演变的影响.模拟结果表明,考虑海洋飞沫的作用后,热带气旋范围内(气旋中心附近600 km左右范围内)的潜热和感热通量明显增强,尤其是潜热通量,最大值可提高35%～80%,潜热通量的大值区对应热带气旋眼墙处的最大风速区.无论是否考虑海洋飞沫作用,模式均能较好地模拟出热带气旋Nabi的移动路径,但考虑飞沫作用后,由于飞沫对海气界面通量交换的贡献,使得模拟热带气旋中心的最低海平面气压降低,最大风速增强,暖心结构更加明显.     

南秦岭观花坪铜银矿床地质特征及找矿标志

观花坪铜银矿床位处南秦岭成矿带中段,矿床产于下寒武-中奥陶统石瓮子组碳酸盐岩建造与中泥盆统大枫沟组碎屑岩建造"不整合接触界面"附近,区域上具明显的层控特征;但在矿区范围内,铜银矿体则严格受断裂破碎带控制,矿体均赋存于叠加在不整合面的断裂破碎带中,明显具后生成矿作用的特点。笔者通过对矿床地质特征、矿体地质特征和矿石特征的研究,结合区域地质背景的分析认为,铜银矿床为多期次多成矿阶段叠加形成的复杂矿床,特别是南秦岭华力西期与印支期—燕山期的构造-岩浆热事件与本区铜银矿床的形成关系密切。     

INFLUENCE OF SPRING EQUATORIAL EASTERN PACIFIC SSTA ON THE SEASONAL CHANGE FROM SPRING TO SUMMER OF EASTERN ASIAN CIRCULATION

Based on the analysis of NCEP height, wind and OLR data, the influence of spring equatorial eastern Pacific SSTA on the seasonal change from spring to summer of eastern Asian circulation has been investigated. Results show that related to the warm (cold) spring SSTA in the equatorial eastern Pacific, the anomalous anticyclone (cyclone) circulation emerges around the South China Sea and the Philippines, the strong (weak) west Pacific subtropical high locates to the west (east) of its normal position, which induces to the late (early) onset of the South China Sea monsoon. The numerical simulations have also shown that the remarkable influence of spring SSTA in the equatorial eastern Pacific on the spring seasonal change of eastern Asian circulation will last till summer.     

甘肃陇中盆地会宁关公滩剖面磁性地层年代学研究

本文对陇中盆地会宁含小哺乳动物化石的关公滩剖面河湖相沉积序列进行了详细的岩石磁学和磁性地层学研究,磁化率各向异性结果表明关公滩剖面沉积物记录了典型的原生沉积组构,沉积物沉积以后几乎没有受到后期的扰动.最大磁化率主轴方向与现今的古水流流向基本一致,表明区域西高东低的地貌至少在中更新世早期已经形成.磁滞回线、等温剩磁获得曲线的矫顽力谱分析、三轴等温剩磁退磁曲线等岩石磁学结果显示：关公滩剖面河湖相沉积物的磁性矿物有磁铁矿、磁赤铁矿和赤铁矿,其中磁铁矿和赤铁矿是主要的剩磁载体,但其特征剩磁载体以赤铁矿为主.系统退磁结果显示,在大部分样品中,磁铁矿和赤铁矿均记录了几乎相同的特征剩磁的方向,整个剖面呈现单一的正极性.另外,关公滩剖面底部河湖相沉积物中产出丰富的小哺乳动物牙齿化石,经初步研究包括复齿鼠兔（Ochotonoides complicidens）、丁氏鼢鼠（Myospalax tingi）、方氏鼢鼠（Myospalax fontanieri）、变异仓鼠（Cricetinus varians）、大林姬鼠（Cricetinus varians）、复齿旱獭（Marmota complicidens）等六个种类,其中丁氏鼢鼠和复齿鼠兔是相对原始的种类,其时代跨越早更新世至中更新世早期,其他都是我国北方中、晚更新世常见的种类,该小哺乳动物化石组合性质表明其时代很可能为中更新世早期.因此,综合磁性地层学和小哺乳动物生物年代学结果,关公滩剖面记录了布容正极性时的沉积,剖面底部堆积及其哺乳动物群的时代应为中更新世早期.     

深渊着陆器坐底位置的精确测量和反演计算

深渊着陆器在下潜过程中,由于受到海流的影响,其坐底位置会偏离投放点,偏离量和偏离方向很难估计,而声学水下定位方法在深渊海区不太适用.通过在海面进行气枪十字放炮作业,利用炮点准确位置和时间信息,以及海底地震仪(Ocean Bottom Seismometer,OBS)记录的直达水波到时,对深渊着陆器的坐底位置进行精确测量可以提供有效定位数据.该方法对采集得到的数据进行预处理,使用蒙托卡洛方法结合最小二乘法,对万泉号着陆器实际坐底位置进行了反演校正,得到三个潜次的位置校正偏移量分别为211m、178m、861m,偏移方向各不相同,校正精度为±20m,比以往的定位精度大为提高.此外,该方法测量确定了三个海底标志物的精确位置,为未来万米无人或载人潜器提供了可靠的水下参考坐标.     

热带气旋影响下江苏强对流天气指数分析

利用10年资料（2001—2010年）对热带气旋影响下的江苏地区强对流天气的发生规律进行统计,发现在各类强对流天气中,短时强降水天气发生频率最高,其次是雷雨大风天气,一般雷暴很少发生,龙卷和冰雹天气从未发生。统计结果还表明,在这10年中共有21个热带气旋影响江苏地区,多数热带气旋处于向热带低压减弱的阶段。通过对相关个例进行强对流指数研究发现,这些指数的阈值比以往的研究要小,表明受热带气旋影响更容易造成对流不稳定和低层不稳定能量堆积,最终导致强对流天气发生。