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91.
利用2007—2017年乌鲁木齐市L波段探空雷达和地面常规观测数据,以Holzworth干绝热曲线原理,估算该地逐日最大边界层高度,并计算对应的边界层平均风速和通风量等数据。同时,应用2015—2017年空气污染指数(AQI),探讨空气质量与大气边界层参数的关系。结果表明:乌鲁木齐市日最大边界层年均高度为1415 m,总体上呈下降趋势,平均降幅为5. 9 m·a-1。时间序列上,日最大边界层高度分布呈明显周期性。逐月数据呈"抛物线"状,1月平均高度最低(336 m),6月平均高度最高(2400 m)。冬季边界层平均风速最小,为2. 6 m·s-1,春季和夏季最大,均为5. 6 m·s-1。一年中,1月平均通风量最小,为977. 0 m^2·s-1,5月平均通风量最大,为14835. 9 m^2·s-1,4—9月为平均通风量大值期,平均通风量为13282. 3 m^2·s-1。大气污染物在风速弱、边界层高度低和通风量小条件下的累积,易造成中度以上污染。冬季,乌鲁木齐常处于蒙古高压后部或底部,为造成冬季污染严重的重要原因之一。 相似文献
92.
干振碎石桩加固液化地基试验研究 总被引:8,自引:3,他引:8
根据高速公路工程液化地基加固试验研究 ,对干振碎石桩加固液化地基的原理、效果、检验方法进行讨论。研究成果表明 ,干振碎石桩用于处理液化地基具有较大的优越性。处理后地基均消除了液化。瞬态瑞利波法具有快捷可靠的优点 ,可以在地基处理质量检测中推广使用。 相似文献
93.
干热岩是一种清洁的可再生地热资源,随着干热岩的开发利用技术日趋成熟,显示出了其巨大的利用价值。干热岩地热资源潜力评估是进行开发利用的基础工作。本文是在充分研究山东省地质构造背景的基础上,通过野外勘查取样和搜集整理地热参数数据,根据浅部温度资料向地壳深部推算的方法,估算出山东省不同区域3~10km深度范围的温度。利用体积法估算出了山东省3~10km深处的干热岩地热资源量。结果显示,山东省3~10km深度范围内干热源资源量总计为2.63×10~(23) J,合8.97×10~(12) t标准煤,现阶段可利用干热岩资源量按2%的可开采资源量计算,即合1794.4×10~8t标准煤,大约是全国能源消耗总量的37倍,开发利用潜在价值巨大。 相似文献
94.
95.
我国东南沿海干热岩赋存前景及与靶区选址研究 总被引:5,自引:0,他引:5
干热岩资源是未来重要的清洁型能源,干热岩资源靶区选址是进行干热岩资源开发利用最基础的工作。本文在综合国内外相关干热岩开发项目的基础上,系统总结了干热岩选址的地热地质学指标,并对我国东南沿海地区的干热岩赋存背景进行论述,选取了广东阳江新州、广东惠州黄沙洞、雷琼断陷盆地、海南陵水等几个地区作为我国东南沿海干热岩开发的重点潜力靶区,在综合分析各靶区深部地热地质背景、深部热异常的基础上,建立了研究区深部温度场模型,进行了干热岩资源靶区选址对比研究,对下一步优先勘查靶区及勘查方案提出了建议。 相似文献
96.
97.
广西地区一次强冰雹过程形成机制分析 总被引:10,自引:5,他引:5
利用NCEP再分析资料、MM5数值模拟资料和多普勒雷达产品,对广西北部2006年4月9~10日的一次强冰雹过程进行动力诊断分析。结果表明,强对流过程发生前期存在的暖干盖,为对流有效位能CAPE的积蓄提供了有利条件。中低层风切变的增加,促进了高低层能量的交换,揭开暖干盖,触发了强对流的爆发。高层位涡的向下输送,引起了低层涡度的变化,形成了低层辐合高层辐散,使得强对流过程得以维持和发展。强对流风暴强中心位于500 hPa以上,低层存在弱回波区,风暴中心的上升从低层到高层发生倾斜,并且沿顺时针方向旋转。 相似文献
98.
Ashley Dubnick Jemma Wadham Martyn Tranter Martin Sharp Joel Barker Elizabeth Bagshaw Sean Fitzsimons 《水文研究》2017,31(9):1776-1789
Cold‐based polar glacier watersheds contain well‐defined supraglacial, ice‐marginal, and proglacial elements that differ in their degree of hydrologic connectivity, sources of water (e.g., snow, ice, and/or sediment pore water), meltwater residence times, allochthonous and autochthonous nutrient, and sediment loads. We investigated 11 distinct hydrological units along the supraglacial, ice marginal, and proglacial flow paths that drain Joyce Glacier in the McMurdo Dry Valleys of Antarctica. We found that these units play unique and important roles as sources and/or sinks for dissolved inorganic nitrogen and dissolved inorganic phosphorus and for specific fractions of dissolved organic matter (DOM) as waters are routed from the glacier into nutrient‐poor downstream ecosystems. Changes in nutrient export from the glacial system as a whole were observed as the routing and residence times of meltwater changed throughout the melt season. The concentrations of major ions in the proglacial stream were inversely proportional to discharge, such that there was a relatively constant “trickle” of these solutes into downstream ecosystems. In contrast, NO3? concentrations generally increased with discharge, resulting in delivery of episodic pulses of dissolved inorganic nitrogen‐rich water (“treats”) into those same ecosystems during high discharge events. DOM concentrations or fluorescence did not correlate with discharge rate, but high variability in DOM concentrations or fluorescence suggests that DOM may be exported downstream as episodic treats, but with spatial and/or temporal patterns that remain poorly understood. The strong, nutrient‐specific responses to changes in hydrology suggest that polar glacier drainage systems may export meltwater with nutrient compositions that vary within and between melt seasons and watersheds. Because nutrient dynamics identified in this study differ between glacier watersheds with broadly similar hydrology, climate, and geology, we emphasize the need to develop conceptual models of nutrient export that thoroughly integrate the biogeochemical and hydrological processes that control the sources, fate, and export of nutrients from each system. 相似文献
99.
Andoni Arenas-Martija Victor Salinas-Silva Leonor Margalef-García Maria Otero-Auristondo 《The Journal of geography》2017,116(2):57-66
This research aims to evaluate the geographical knowledge of nine teachers in the region of Valparaiso, Chile. An interpretive case study was conducted with data collected through classroom observations, interviews, and questionnaires, and these data were then analyzed through triangulation. The findings showed that these teachers, who are the most qualified within the region's context, consider geography to be marginal knowledge in the school curriculum, although they also consider it relevant to the education of their pupils. Both elements provided evidence of the fragility of their geographical knowledge, which fell within a spectrum that combines expert knowledge and lay knowledge. 相似文献
100.
Soybean expansion, driven by growing global meat demand, has accompanied neotropical deforestation in past decades. A recent decoupling between soybean production and deforestation in Brazil is taken as evidence of efficient deforestation regulation. Here, we assessed the relationships between soybean economy, livestock production and deforestation from 1972 to 2011 in Northern Argentina Dry Chaco. We used Panel Analysis to evaluate the relationship between soybean cultivated and deforested area in different periods and we used high resolution time series analysis of a deforestation hotspot, to explore links between soybean economy, cattle ranching and deforestation. In northern Argentina, 2.7 millions ha were deforested from 1972 to 2011, 56% of which occurred after 2002. The results of the Panel analysis indicate a strong link between soybean expansion and deforestation but with variation among periods mediated by the links between soybean and livestock productions. Deforestation was strongly coupled with soybean expansion during the 1972–1997 and 2002–2011 periods; but was largely decoupled between 1997 and 2002, when strong increments in production were accompanied by low deforestation. The high resolution analysis also indicated contrasting levels of association after and before 1997. The soybean deforestation decoupled periods in Brazil and Argentina shared similarly weak economic incentives for soybean production, rapid technological innovation and preceding high deforestation periods. In the Argentine case, when economic incentives turned positive after a 5-years decoupled period, new government measures were unable to regulate deforestation. Our study suggests that macroeconomic factors can be a much stronger deforestation force compared with domestic legal frameworks. Effectiveness of neotropical deforestation regulation should be carefully monitored and interpreted with caution paying special attention to global economic context for soybean expansion. 相似文献