袁河流域强降水的天气背景与回波特征分析

为了更好地监测预警江西袁河流域强降水天气,使用江西雨量资料、欧洲中心格点（1°×1°）再分析资料和江西雷达回波等资料,对袁河流域5次大暴雨过程进行分析,结果表明：（1）袁河流域强降水天气形势场是925～700 hPa切变线、低层辐合高层辐散中心、西南气流达到12～18 m·s-1等因素影响;T-LnP图上整层水汽充沛,可降水量在75 mm以上;降水前低层累积不稳定能量CAPE（1000 J/Kg）和对流抑制能CIN（100 J/Kg）。（2）强降水回波的组合反射率CR在50 dBz左右,回波顶高在13 km左右,垂直积分液态水含量在12 kg·m2左右;40 dBz回波顶高在6～7 km,45 dBz回波顶高在6.5 km以下。（3）强降水和回波强度dBZ成正相关,随降水的增强,回波明显增强;当回波强度≤20 dBz时,雨强几乎不变;当回波强度在20～35 dBz之间,雨强随回波强度增加而缓慢加大;当回波强度在35～50 dBz之间,雨强随回波强度加大明显增加;而当回波强度≥50 dBz时,雨强反而趋于下降或维持。研究结果对袁河流域强降水的监测预警和预报服务有指导意义。     

青岛市短时强降水的气候特征和天气系统分型

利用1981—2012年4—10月青岛市7个观测站逐时降水量资料和同期NCEP再分析资料,统计分析青岛市短时强降水的时空分布特征,建立青岛市短时强降水天气概念模型。结果表明：青岛市年短时强降水日数无明显变化趋势;4—10月均有短时强降水出现,7—8月是多发月份;短时强降水的日变化有2个多发时段,主峰在下午到傍晚时段,次峰在凌晨时段;即墨、平度、黄岛为青岛市短时强降水的多发区域,其中黄岛为连续性短时强降水出现最多的区域;青岛市产生短时强降水的天气系统可分为六种类型,西风槽型、横槽型、冷涡型、热带低值系统型、西北气流型、切变线型,其中西风槽型出现次数最多。     

ENSO事件对云南及临近地区春末初夏降水的影响

本文采用合成及相关分析的方法,应用55年中国降水资料、美国NOAA海表温度资料以及NCEP/NCAR再分析资料,研究了ENSO事件对我国云南及其邻近地区春末初夏降水的影响及物理机理.研究结果表明:(1)在El Ni(n)o (La Ni(n)a)年,云南大部分地区4～5月降水偏少(多),东部地区相关信号尤其明显;(2)...     

“95.8”川西大暴雨成因分析

通过对“９５．８”大暴雨过程的全面技术总结，揭示了多种尺度系统间相互作用对产生大暴雨过程的贡献，并指出了云团的发生及其发展源于北方冷空气和南方低空急流持续影响所形成的两个中间尺度垂直环流。     

大尺度环流的年代际变化对初夏华南持续性暴雨的影响

利用1961-2010年中国逐日降水数据和NCEP/NCAR逐日再分析资料集,研究了大尺度环流的年代际变化对不同频发年代华南持续性暴雨的影响。结果表明,虽然过去50年里华南持续性暴雨的发生存在两个频发时段(20世纪60年代中期到70年代中期、20世纪90年代初到2010年),其典型环流配置都表现为中高纬度冷空气和低纬度充沛水汽的配合,但不同频发时段的大尺度环流配置明显不同,这种配置使得两个频发时段的暴雨发生特点有所不同,最近20年的暴雨发生次数更多,强度更强,持续时间更长。在频发的1964-1976年,高纬度的冷空气主要来自西西伯利亚上空深厚的低槽前部,而此时南亚高压偏弱,西太平洋副热带高压偏弱、偏东,低纬度的水汽主要来自孟加拉湾印缅低压槽前,可降水量偏小,但垂直速度较大,水汽辐合较旺盛,华南上空大气环流较不稳定;在频发的1991-2010年,鄂霍次克海上空附近的高压脊活跃,高纬度冷空气主要来自高压后部,低纬度西太平洋副热带高压偏强,位置偏西,其西北侧的水汽源源不断输送到华南上空,故可降水量增多,伴随着强大的南亚高压提供的良好的高层辐散条件,华南上空垂直速度增大,水汽辐合明显,强有利的环流配置导致1991-2010年华南持续性暴雨强度更大、范围更广。因此,大气环流的年代际转型使得华南持续性暴雨发生了巨大改变,故在未来做预测时应充分考虑不同年代际环流背景场对华南持续性暴雨的重要影响。     

T639数值产品对影响新疆主要系统的预报检验评估

使用T639L60模式2009—2010年1°×1°分辨率72 h预报时效内的高度场预报产品及ECMWF客观分析场,采用天气学检验方法,对新疆主要天气影响系统(西西伯利亚低槽、乌拉尔大槽、北方横槽和中亚低值系统)数值产品的预报能力进行检验。主要从影响系统生成时间、中心强度、槽线位置、移动速度4个方面进行检验。检验结果表明:T639模式对新疆影响系统具有较好的预报性能,尤其对48h内的预报能力非常高。但因影响系统和预报时效不同其预报能力也有较大差异,对越深厚的低槽系统,T639模式的预报效果越好;T639产品对西西伯利亚低槽和乌拉尔大槽出现时间预报偏早的较多,而北方横槽和中亚低值系统偏晚的多;对西西伯利亚低槽和中亚低值系统槽线位置预报偏快的较多,而乌拉尔大槽和北方横槽偏慢的多。     

The Linkage between Midwinter Suppression of the North Pacific Storm Track and Atmospheric Circulation Features in the Northern Hemisphere

The midwinter suppression(MWS) of the North Pacific storm track(NPST) has been an active research topic for decades. Based on the daily-mean NCEP/NCAR reanalysis from 1948 to 2018, this study investigates the MWS-related atmospheric circulation characteristics in the Northern Hemisphere by regression analysis with respect to a new MWS index, which may shed more light on this difficult issue. The occurrence frequency of the MWS of the upper-tropospheric NPST is more than 0.8 after the mid-1980 s. The MWS is accompanied by significantly positive sea-level pressure anomalies in Eurasia and negative anomalies over the North Pacific, which correspond to a strengthened East Asian winter monsoon. The intensified East Asian trough and atmospheric blocking in the North Pacific as well as the significantly negative low-level air temperature anomalies, lying upstream of the MNPST, are expected to be distinctly associated with the MWS. However, the relationship between the MWS and low-level atmospheric baroclinicity is somewhat puzzling.From the diagnostics of the eddy energy budget, it is identified that the inefficiency of the barotropic energy conversion related to the barotropic governor mechanism does not favor the occurrence of the MWS. In contrast, weakened baroclinic energy conversion, buoyancy conversion, and generation of eddy available potential energy by diabatic heating are conducive to the occurrence of the MWS. In addition, Ural blocking in the upstream region of the MNPST may be another candidate mechanism associated with the MWS.     

泵吸反循环钻进工艺在桩基施工中的应用

介绍了泵吸反循环钻进的施工特点、适用范围，施工中的技术要求与常见故障的原因及处理方法。     

Late Quaternary clay minerals off Middle Vietnam in the western South China Sea: Implications for source analysis and East Asian monsoon evolution

High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are re-ported to reconstruct a history of East Asian monsoon evolution. Variations in Illite, chlorite, and kaolinite contents indicate a strong glacial-interglacial cyclicity, while changes in smectite content present a higher frequency cyclicity. The provenance analysis indicates a mixture of individual clay minerals from various sources surrounding the South China Sea. Smectite derived mainly from the Sunda shelf and its major source area of the Indonesian islands. Illite and chlorite originated mainly from the Mekong and Red rivers. Kaolinite was provided mainly by the Pearl River. Spectral analysis of the kaolin-ite/(illite chlorite) ratio displays a strong eccentricity period of 100 ka, implying the ice sheet-forced win-ter monsoon evolution; whereas higher frequency changes in the smectite content show an ice sheet-forced obliquity period of 41 ka, and precession periods of 23 and 19 ka and a semi-precession period of 13 ka as well, implying the tropical-forced summer monsoon evolution. The winter monsoon evolution is generally in coherence with the glacial-interglacial cyclicity, with intensified winter monsoon winds during glacials and weakened winter monsoon winds during interglacials; whereas the summer monsoon evolution provides an almost linear response to the summer insolation of low latitude in the Northern Hemisphere, with strengthened summer monsoon during higher insolation and weakened summer monsoon during lower insolation. The result suggests that the high-latitude ice sheet and low-latitude tropical factor could drive the late Quaternary evolution of East Asian winter and summer monsoons, respectively, implying their diplex and self-contained forcing mechanism.     

准噶尔盆地腹部白垩系清水河组清一段高分辨率层序地层特征及岩性油气藏预测

通过钻井、岩芯和测井等资料的分析，清水河组清一段划分出1个长期基准面旋回、2个中期基准面旋回和5个短期基准面旋回。MSC1中期基准面旋回主要为辫状河三角洲沉积，MSC2中期基准面旋回为湖泊相沉积，局部地区夹有辫状三角洲沉积，极易形成岩性油气藏。区域性隔层发育在非对称型长期基准面旋回的上部，有利的储集体主要分布于中期基准面上升的早期。