塔里木盆地一次东灌型沙尘暴环流动力结构分析

利用NCEP再分析资料和常规地面观测资料,对2006年4月10日塔里木盆地发生的一次东灌型沙尘暴,从气候背景、环流形势、螺旋度场、锋生次级环流、温度平流等方面进行分析,揭示了此类沙尘暴强盛期的环流动力结构。结果表明：①里咸海脊、乌拉尔脊、新地岛脊同位向叠加,西西伯利亚横槽转竖南下,引导泰米尔半岛强冷空气爆发直插新疆,东灌进入南疆盆地,造成大范围沙尘暴天气;②西西伯利亚地面冷高压爆发性南下并强烈发展是造成此次沙尘天气的根本原因;③盆地前期的干暖形势为沙尘暴的产生提供了有利的热力条件;④沙尘暴区上空螺旋度垂直分布为低层正值、高层负值,构成低空强辐合、高空强辐散的上升运动区,揭示强旋转上升运动是大范围沙尘暴发生的动力条件;⑤高空急流入口区次级环流下沉支导致高层动量下传 ,促使对流层中低层风力加大,冷锋南压,驱动沙尘天气的发生。     

星基多光谱分析的降水估算

<正>对从已广泛应用的全球气候模型到局地降水和洪灾的预报而言,准确估算降水的数量、时间和空间分布是至关重要的。降水作为地球水循环的一个关键组成部分,对于人类的生命财产安全有着重要的影响。从区域到全球尺度,现存的地基降水观测网络是不足的;因此,卫星提供了一种可行和吸引人的选择。很显然,     

新疆东部黑戈壁地表辐射及能量收支演变特征

新疆东部黑戈壁作为气候恶劣、人迹罕至的生态脆弱区,具有丰富的太阳能资源。利用红柳河陆气相互作用观测站2019年4、7、9月观测资料,分析东疆黑戈壁地表辐射及能量收支演变特征。结果表明：（1）地表辐射及能量收支各分量日变化均为单峰型。就不同季节而言,太阳总辐射和净辐射为夏季>春季>秋季,反射短波辐射为春季>夏季>秋季,地表和大气长波辐射为夏季>秋季>春季。（2）能量收支各分量季节变化明显,感热通量为春季>夏季>秋季,潜热通量为夏季>秋季>春季,地表土壤热通量为秋季>夏季>春季;能量分配在不同季节均以感热为主,地表土壤热通量次之,潜热通量极其微弱。（3）地表反照率日变化均为“U”型,在不同季节表现为春季>秋季>夏季,依次为0.29、0.27、0.26。东疆黑戈壁地表反照率整体较高,这是下垫面为黑色砾石所致。     

新疆沙尘暴研究进展

沙尘暴是风蚀荒漠化中的一种天气现象,既是加速土地荒漠化的重要过程,又是土地荒漠化发展到一定程度的具体体现.新疆地处我国西北干旱、半干旱区,是我国荒漠化土地最多的省区,也是风沙危害最严重的地区之一.重点论述了新疆地区沙尘暴的若干研究进展,从6个方面对沙尘暴的形成及研究现状进行综述,即新疆沙尘暴气候背景、长期变化趋势、分布...     

Infiltration-recharge through wadi beds in arid regions

Abstract

Groundwater recharge in arid regions is intermittent and usually occurs as a result of flood flow transmission losses in dry wadi channels. Hydrograph characteristics play a dominant role in determining the amount of channel abstraction in relation to the width of the wetted perimeter and the time of inundation, and the subsequent groundwater recharge. Large variations in the magnitude of channel losses result mainly from the diversity in inflow volumes. The magnitude of groundwater recharge in relation to bed transmission losses is dependent on flood volume and duration, soil moisture content and physical soil profile characteristics. Runoff volume and duration are the dominant factors influencing the cumulative infiltrated volume and recharge to shallow water tables. Taking into consideration the influence of various hydrological and channel characteristics, several regression equations are suggested to estimate the transmission losses from a wadi bed and the groundwater recharge.     

Using Portable Gamma-Ray Spectrometry for Testing Uranium Migration: A Case Study from the Wadi El Kareim Alkaline Volcanics, Central Eastern Desert, Egypt

The 300±20 Ma anomalously radioactive trachytes of Wadi El Kareim, central Eastern Desert, are a significant example of U-mineralization related to the alkaline volcanics in Egypt. Extensive portable gamma-ray spectrometric data has been utilized to identify geological factors controlling uranium mobility in the geological units along the three detailed study locations of Kab Al-Abyad, South Wadi (W) Al-Tarafawy and W. Al-Farkhah; their eTh/eU ratios averaging around 4.1, 3.7 and 5.6 respectively. Quantitative analysis with the integration of mobility maps and geological studies suggest two systems controlling U-migration within the geological units (confined system and unconfined system). In the confined system, the syngenetically formed U have experienced mobility after leaching and are redistributed in the presence of an incorporation carrier during transportation (probably as carbonate complexes). Then the retardant for uranium is achieved by sorption or by coprecipitation with the aid of Fe oxy-hydroxide, and finally the formation of immobile secondary U-bearing minerals takes place along a lithogeochemical trap. In contrast to the confined system, the unconfined one is basically lacking the lithogeochemical trap which in?uences the final accumulation of U-bearing minerals. The radioactivity of the trachyte rocks arises from the radioactive minerals uranophane and beta-uranophane with U- and/or Th-bearing minerals samarskite, Th-rich REE silicates, monazite and allanite.     

塔中涡动资料不同坐标旋转方法比较分析

坐标旋转是涡动协方差(EC)通量观测数据后处理当中必须进行的步骤,本文利用塔克拉玛干沙漠腹地塔中西面标校站自然沙丘上3 m高度和塔中本站32 m高度2009年4—10月湍流通量数据,对比分析了不同坐标旋转方法在塔中通量观测数据中的应用。结果表明,塔克拉玛干沙漠腹地塔中湍流各通量在旋转订正前后差别不显著,不订正造成的通量计算误差1%。塔中32 m和塔中西站3 m通量计算误差,与两个站点的采集仪器架设高度差别较大有关。即使对于相对平坦的下垫面,也必须要进行倾斜校正,以修正地势、仪器振动、安装倾斜等产生的虚假信息。本研究对塔中涡动资料进行旋转时采用了二次坐标旋转方法。此结果为塔克拉玛干沙漠腹地EC通量观测的风速仪倾斜校正提供参考。     

气泡混合轻质土试样制备研究

由于气泡消泡的缘故,室内制备和现场浇筑气泡混合轻质土时存在塌陷问题。为分析和解决该问题,以砂土为原料土,开展了不同温差、湿度和掺砂与否条件下3种密度气泡混合轻质土的制备试验,并测定了各试样的高度和强度,基于热力学理论分析了3种因素对试样制备和强度的影响规律。试验结果表明,试样制备时温度与养护温度之间的温差是影响气泡混合轻质土胀缩性的决定性因素,轻质土中的气泡含量越高,受温差影响越大,通过控制温差即可解决塌陷问题;湿度和掺砂与否对气泡混合轻质土的试样制备影响不明显,但是湿度高会延长试样脱模时间以及影响试样的完整性;温差和温度共同影响气泡混合轻质土的早期强度,其中温差主要影响试样密实度,温度主要影响水泥水化反应速率。试验结果可为气泡混合轻质土制备和施工时间点选择提供借鉴。     

Three-Dimensional Structural Modelling and Source Rock Evaluation of the Quseir Formation in the Komombo Basin, Egypt

The Quseir Formation consists mainly of dark gray mudstones with a high organic matter content and excellent hydrocarbon-generating potential. The main objectives of this study are to highlight the dominant structural elements in the Komombo Basin, Egypt, and evaluate the geochemical characteristics of the Quseir Formation. Depth maps and a 3 D structural model indicate two normal fault trends NW–SE and ENE–WSW. The NW–SE trend is the dominant one that created the primary half-graben system. The...     

The Chinese Carbon-Neutral Goal: Challenges and Prospects

On 22 September 2020, within the backdrop of the COVID-19 global pandemic, China announced its climate goal for peak carbon emissions before 2030 and to reach carbon neutrality before 2060. This carbon-neutral goal is generally considered to cover all anthropogenic greenhouse gases. The planning effort is now in full swing in China, but the pathway to decarbonization is unclear. The needed transition towards non-fossil fuel energy and its impact on China and the world may be more profound than its reform and development over the past 40 years, but the challenges are enormous. Analysis of four representative scenarios shows significant differences in achieving the carbon-neutral goal, particularly the contribution of non-fossil fuel energy sources. The high target values for nuclear, wind, and bioenergy have approached their corresponding resource limitations, with solar energy being the exception, suggesting solar’s critical role. We also found that the near-term policies that allow for a gradual transition, followed by more drastic changes after 2030, can eventually reach the carbon-neutral goal and lead to less of a reduction in cumulative emissions, thus inconsistent with the IPCC 1.5°C scenario. The challenges and prospects are discussed in the historical context of China’s socio-economic reform, globalization, international collaboration, and development.