美国极地钻探科学目标分析与钻探技术进展

极地钻探是获取极地冰层或冰下环境样品和在极地冰层或冰下布放科学观测仪器的最直接方法,是开展极地科学研究的必要技术手段。美国是开展极地钻探较早的国家之一,也是极地钻探强国。相比美国,我国极地钻探技术尚处于起步阶段。本文以《美国冰钻委员会长期科学规划2021-2031》为基础,结合其官方网站和相关文献资料,梳理了美国极地钻探科学目标和极地钻探技术现状,并简要介绍了过去10年美国极地钻探的现场工作情况及其在未来3年的工作计划,以期为我国极地钻探发展提供参考。     

Geochronology of the Xihuashan Tungsten Deposit in Southeastern China: Constraints from Re–Os and U–Pb Dating

Xihuashan tungsten deposit is one of the earliest explored tungsten deposits in southeastern China. It is a vein type deposit genetically associated with the Xihuashan granite pluton. Here we report new dating and zircon geochemistry results. Re–Os isotopic dating for molybdenite intergrowth with wolframite in the oldest generation of the Xihuashan pluton yielded an isochron age of 157.0 ± 2.5 Ma (2σ). Zircon U–Pb laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) dating shows that the pluton crystallized at 155.7 ± 2.2 Ma (2σ). This age is similar to the molybdenite Re–Os age for the ore deposit within error. This, together with published data, suggests that the major W(Mo)‐Sn mineralization occurred between 160–150 Ma in southeastern China. These deposits constitute a major part of the magmatic‐metallogenic belt of eastern Nanlin. The lower Re content in molybdenite of the Xihuashan tungsten deposit shows crustal origin for the ore‐forming material. The limited direct contributions from the subducting slab for the tungsten mineralization in the Nanling region suggest a change of the style of the paleo‐Pacific plate beneath southeastern China.     

渤海湾盆地东营凹陷南斜坡断裂趋势带形成机制与控藏作用

断裂趋势带是指盆地基底断裂继承性活动或盖层受到剪切作用影响而产生在盖层中的弱变形构造带,是主断裂面形成前的变形程度较弱的构造带。研究发现,东营凹陷南斜坡王家岗和八面河断裂趋势带是由一系列雁列式排列小断层带组成的,具有上宽下窄,下部收敛于主走滑断裂的特点。由于浅层没有主断层显现,故也称这种构造带为隐性断裂带,其形成机制和变形程度不同,发育的圈闭数量、圈闭性质等特征不同,富集油气的能力也有差异。构造物理模拟实验表明,王家岗和八面河断裂趋势带都形成于基底断裂走滑—伸展双重作用,前者走滑—伸展运动方向夹角为40°~50°,后者夹角为20°左右。前者处于断裂带发育的幼年期,变形程度较弱,趋势带宽度小,断裂密度小;后者处于断裂带发育的青年期,变形程度强,趋势带宽度大,断裂密度大,形成与断裂相关的圈闭数量多,油气聚集能力高于前者。根据断裂趋势带演化阶段、发育特征和源藏匹配关系,认为断裂趋势带变形强度是控制油气富集程度的关键因素。王家岗断裂趋势带成藏模式为“幼年期弱变形—单洼供烃成藏模式”,八面河断裂趋势带成藏模式为“青年期强变形—双洼供烃成藏模式”。     

高空槽对两类热带气旋变性阶段强度变化影响的数值模拟研究

选取9711号台风"Winnie"和0713号台风"Wipha"分别作为变性加强和变性减弱类台风个例进行数值模拟,而后利用模式结果对大尺度场及涡度收支场进行诊断分析。结果表明:台风"Winnie"变性过程中,其西北侧高空槽呈西北—东南走向,南亚高压强度弱,对高空槽东移阻塞作用小。变性前期阶段主要是锋面系统和斜压性起关键作用,变性完成后,"Winnie"在斜压、高层辐散及涡度平流的共同作用下再次加强。台风"Wipha"变性过程受强大的南亚高压和副高影响,其西北侧高空槽稳定少动且呈东北—西南走向,冷空气入侵不明显,斜压区面积和强度都受到了限制。另外高层辐散场和涡度平流场均未能为"Wipha"提供有利的环境使其再加强。     

水汽场初值调整及其对华南降水预报贡献的研究

该文利用GMS多通道气象卫星资料推导得到的降水资料估算出的加热率, 作为非绝热的非线性正规模初始化过程中的非绝热强迫项, 进行风压场的初值调整, 再采用一个与模式中的对流参数化方案相反的逆运算方案, 进行水汽场的初值调整.以保证初始时刻按模式的物理参数化方案计算得到的加热率与由卫星推导的加热率一致. 这一方法在非绝热的非线性正规模初值化的框架中, 使初始时刻的水汽场得到调整.既实现了传统的初始化目标, 又提高了模式对降水的短时预报效果.对华南的两个个例的试验结果表明该文的方法是有效的.     

The 2020/21 Extremely Cold Winter in China Influenced by the Synergistic Effect of La Niña and Warm Arctic

In the first half of winter 2020/21,China has experienced an extremely cold period across both northern and southern regions,with record-breaking low temperatures set in many stations of China.Meanwhile,a moderate La Ni?a event which exceeded both oceanic and atmospheric thresholds began in August 2020 and in a few months developed into its mature phase,just prior to the 2020/21 winter.In this report,the mid?high-latitude large-scale atmospheric circulation anomalies in the Northern Hemisphere,which were forced by the negative phase of Arctic Oscillation,a strengthened Siberian High,an intensified Ural High and a deepened East Asian Trough,are considered to be the direct reason for the frequent cold surges in winter 2020/21.At the same time,the synergistic effect of the warm Arctic and the cold tropical Pacific(La Ni?a)provided an indispensable background,at a hemispheric scale,to intensify the atmospheric circulation anomalies in middle-to-high latitudes.In the end,a most recent La Ni?a prediction is provided and the on-coming evolution of climate is discussed for the remaining part of the 2020/21 winter for the purpose of future decision-making and early warning.     

定量分析几种Q矢量

结合1991年7月5日20:00～6日20:00一次典型的江淮梅雨锋暴雨过程，从台站实际业务工作需要考虑，细致、具体地比较分析了850 hPa、700 hPa及500 hPa 3个层次的准地转 Q 矢量散度场、半地转 Q 矢量散度场、非地转 Q 矢量散度场及湿 Q 矢量散度场与相应时刻地面降水场对应关系的差异，同时还针对每一种 Q 矢量，将其在850 hPa、700 hPa及500 hPa 3个层次的散度场对同时刻降水场的反映能力进行了比较。在定量比较的基础上，得到了对4种 Q 矢量诊断特性的具体认识:（1）在整个梅雨锋暴雨过程中，3个层次的半地转 Q 矢量散度场及准地转 Q 矢量散度场对雨区的反映能力较小，而非地转 Q 矢量的散度场和湿 Q 矢量的散度场对雨区的反映能力明显较前二者大，尤其是湿 Q 矢量散度场在每个层次的诊断能力基本都大于相应层次的其它 Q 矢量的散度场。（2）对于每一种 Q 矢量而言，基本都是在700 hPa的散度场与雨区的对应关系好于各自在850 hPa和500 hPa的散度场，尤其是700 hPa湿 Q 矢量散度辐合场对同时刻梅雨锋暴雨的强度及落区都有很好的指示作用。最后，基于理论的角度对各 Q 矢量的诊断特性进行了较为深入地探讨和比较分析，明确地指出了4种 Q 矢量存在理论前提上的差异。     

The characteristics of ultraviolet radiation in arid and semi-arid regions of China

Measurements of the broadband global solar radiation (R _S) and total ultraviolet radiation (the sum of UV-A and UV-B) were conducted from 2005 to 2010 at 9 sites in arid and semi-arid regions of China. These data were used to determine the temporal variability of UV and UV/R _S and their dependence on the water vapor content and clearness index. The dependence of UV/R _S on aerosol optical depth (AOD) and water vapor content was also investigated. In addition, a simple and efficient empirically model suited for all-weather conditions was developed to estimate UV from R _s. The annual average daily UV level in arid and semi-arid areas is 0.61 and 0.59 MJ m^?2 d^?1, respectively. The highest value (0.66?±?0.25 MJ m^?2 d^?1) was recorded at an arid area at Linze. The lowest value (0.53?±?0.22 MJ m^?2 d^?1) was recorded at a semi-arid area at Ansai. The highest daily value of UV radiation was measured in May, whereas the lowest value was measured in December. The monthly variation of the UV/R _s ratio ranged from 0.41 in Aksu to 0.35 in Qira. The monthly mean value of UV/R _s gradually increased from November and then decreased in August. A small decreasing trend of UV/R _s was observed in the arid and semi-arid regions due to recently increasing amounts of fine aerosol. A simple and efficient empirically model suit for all-weather condition was developed to estimate UV from R _s. The slope a and intercept b of the regression line between the estimated and measured values were close to 1 and zero, respectively. The relative error between the estimated and measured values was less than 11.5%. Application of the model to data collected from different locations in this region also resulted in reasonable estimates of UV.     

长岛县旅游气候舒适度分析

气候舒适度是影响一个地区旅游资源开发和发展以及旅游季节游客数量的重要因素。利用长岛国家基本气象站1986—2015年的气温、降水、风速、相对湿度和日照时数等与旅游气候舒适度相关的气象观测资料,对山东省烟台市长岛县气候舒适度进行研究计算,划分出长岛适宜于旅游的季节分布;结合2011—2015年长岛县游客的月统计资料,分析研究长岛旅游气候舒适度与游客数量之间对应关系。结果表明:长岛县5—10月均较适宜旅游,其中最佳旅游时间段为6—9月,其他月份气候舒适度等级较低,基本不适合旅游。旅游游客数量与气候舒适度密切相关,综合气候舒适度指数每变化一个单位,长岛县游客数量月指数增加2.098个百分点。     

2000年以来黑龙江省浓雾气候特征及秋季浓雾天气异常环流特征

探讨了黑龙江省2000年以来浓雾时空分布特征以及秋季浓雾异常环流特征和环流分型。结果表明：黑龙江省浓雾春季和冬季少,夏季最多,但多发生在山区,持续时间短,局地性强;范围大、持续时间长、灾害重的浓雾天气主要出现在秋季,其中10—11月持续性浓雾天气过程均发生在2010年以后。黑龙江省秋季浓雾多发生在暖湿空气较强的环境条件下,根据500 hPa高度场和距平场特征把秋季偏暖背景下浓雾发生的主要环流型分为西低东高型和纬向型,黑龙江省中低层正高度距平、850 hPa距平风场上反气旋环流以及西北太平洋副热带高压常偏北偏强等异常环流特征对浓雾中短期预报有较好的指示意义。