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To grasp the evolution of urban lakes accurately is quite necessary for studying on the mechanism of city ecological development. The study about extraction with different types of water by remote sensing technology has developed for decades. Many water indexes as the main methods are used to extract water information. Each method has advantage and disadvantage in different situation. A synergistic approach in this study can reduce the uncertainty of urban lake extraction by using four methods: NDWI, MNDWI, RNDWI and SPM. The basic idea behind the synergistic approach is to give each pixel a score based upon the agreement among the different products of four water extraction methods. According to the score of each pixel, the synergy map, which has been created by the products of four methods, is decomposed into sixteen sub-synergy maps. We use Bayesian Decision Theory to screen out the sub-synergy maps with low confidence level. The remaining ones are recombined a refined map. The overall accuracy of refined map reaches 96.44%, higher than any one of the four methods. Wuhan, known as the City of Hundred Lakes, is selected as the study area. We use the synergistic method to keep track of twenty lakes in Wuhan City changing from 1990 to 2013. The total area of twenty lakes has reduced from 130.2478 km2 to 102.2971 km2 during twenty-three years. The area of Shaihu Lake, which is the most serious of all observed lakes, has shrunk by 77.27%. And Nanhu Lake has lost 8.5 km2 of its area that is the most among all lakes. We also find 1990–2000 is the high tide of urban lake shrinking. After the year of 2000, the situation of lake shrinking has been controlled gradually. 相似文献
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利用呼图壁县及周边15个气象站点1980-2020年气候资料和地理信息数据,通过地统计回归和反距离权重等方法构建≥10℃积温、无霜期、7月平均气温、≥15℃持续日数、≥20℃积温等指标因子与地理因子的空间分析推算模型,获取棉花各区划指标因子的空间分布模拟值,并将实际值与模拟值之残差部分进行空间内插订正,结合棉花区划指标等级,最终得到棉花种植精细化气候区划。区划结果表明,全县划分为适宜区、次适宜区、风险区和不适宜区4个分区。适宜种植区主要分布在呼图壁县海拔510 m以下的北部平原地区,包括园户村镇、111团场、105团场、106团场、芳草湖农场的平原地区;次适宜区主要分布在呼图壁县海拔510~650 m之间的乌奎高速公路附近地带,包括呼图壁镇、十里店镇、五工台镇和大丰镇南北两侧的平原地区;风险棉区主要分布在呼图壁县以南海拔650~850 m之间的山前倾斜平原;不宜棉区主要分布在海拔高度850 m以上,包括石梯子乡、雀尔沟镇以南中高山在内。研究成果可为当地农业种植布局调整提供科学参考。 相似文献
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本文利用位于参考平面上的无限延仲的三棱质体模型检验了解析延拓解(至一次项)和借助地形数据解在解算垂线偏差时的精度,并对这两个解在理论上和实用上的优劣程度进行了详细分析,得到了在计算垂线偏差时加入解析延拓解的一次项的精度还不如直接用法耶异常代入Venig Meinesz公式的精度高的新论点,并进一步验证了借助地形数据解的精确性和在实用中的优越性。 相似文献
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万瑜 《沙漠与绿洲气象(新疆气象)》2014,8(1):32-38
利用ECMWF细网格数值预报产品和区域自动站、风廓线雷达等常规观测资料,对乌鲁木齐2013年春季南郊发生的一次东南大风过程进行诊断分析和预报释用,揭示了乌鲁木齐东南大风发生和维持的物理机制,发现细网格资料在预报时空分辨率和预报性能等方面均有提高,对东南大风预报具有指示意义,提高了预报的准确性。分析表明:达坂城至南郊一带东南风频发是由于春季地面蒙古高压部分南掉,形成东西间气压梯度力同乌鲁木齐南郊地形狭管方向一致时,并在“慢坡”重力下滑的共同作用下所形成的回流型东南大风;细网格850hPa风矢量、10m高度上的风、海平面气压场、2m高度上的温度等要素预报,对乌鲁木齐南郊东南大风的起止时间、风速量级及落区的预报有较好指示意义。 相似文献
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回收利用以碳还原等方法生产碳酸锶废渣中的锶元素,有利于提高锶资源的综合利用水平,减少碳酸锶生产带来的环境污染。以碳酸锶废渣为原料,采用盐酸浸取的方法,经过氯化锶精制等工艺,回收得到了高纯氯化锶;并且研究了浸取过程中温度、酸用量、水用量和反应时间等对浸取效果的影响,得出了浸取过程的最佳工艺参数。常温下,当碳酸锶废渣为100 g,中和pH为12时,盐酸用量约1 mol;用水量约600 mL;反应时间2 h;碳酸锶废渣中锶的回收率为78%;得到的氯化锶含量大于99.5%。 相似文献
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利用2011年7月至2014年6月的ECMWF细网格2m温度预报产品,采用格点映射站点和双线性插值法挑选最优预报参考格点,并用天气学检验方法,对该模式在不同季节、不同天气时的乌鲁木齐市温度预报能力进行检验。检验表明:该产品对制作乌鲁木齐未来24小时温度预报具有很好的指导意义,全年的最高最低温度预报准确率为74~75%,季节变化明显,夏半年的预报准确率高出冬半年10~25%;模式对降雨、降雪时的温度预报较好,大雾时最差,并且会使最低气温预报严重低于实况,对东南风时最高气温预报好于最低气温;该产品整体上在准确率和稳定性上均优于中央台指导预报,在春季具有明显优势,高低温正技巧可达0.4℃。 相似文献
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辽宁省乡镇天气预报业务系统以高分辨率中尺度数值预报和自动气象站等加密观测数据为基础,以数值预报解释应用技术为依托,应用PP方程组和相似法结合制作乡镇站点的降水预报,建立起比较完善的乡镇天气预报业务流程,开发了辽宁省乡镇天气预报网站,实现了未来24 h辽宁省952个乡镇站点的降水、最高气温和最低气温3个要素的乡镇短期基本气象要素预报产品在网页上的下发、订正、保存、上报、评分和管理等功能。同时,概述了辽宁省乡镇天气预报系统的技术方法和工作流程。 相似文献
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The kinematic rupture process of the 2011 Tohoku-Oki earthquake (Mw 9.0) was derived given apparent source time functions (ASTFs) retrieved from Rayleigh waves using a refined homomorphic deconvolution method. The total duration of the rupture process was about 165 s. Three slip-concentrated areas were identified based on images of static slip distribution. The largest asperity, located up-dip from the hypocenter with an area of 250 km × 110 km extending to the trench on the fault, had a maximum slip of about 54 m. The other asperities with smaller slip down-dip from the hypocenter were centered on the north and south of the hypocenter, respectively. The preferred average rupture expansion velocity was 1.2 km/s within 130 km from the hypocenter and up to 2.3 km/s over other areas on the fault. Thus, the region near the vicinity of the hypocenter with lower rupture velocity had higher slip amplitude, strongly suggesting brittle failure on a high friction fault. Based on ASTF results, our proposed method offers another way of directly detecting the kinematic source parameters of earthquakes. 相似文献