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21.
为定量研究公路对气温观测的影响,本文使用2014年1—5月在陕西省开展的两组公路观测试验的逐分钟温度、风向、风速等气象资料,对比分析了合阳县国道和渭蒲高速公路在不同季节、不同天空状况以及不同背景风速条件下对周围环境气温观测的影响程度和影响距离。试验结果表明:公路对周围的环境温度有一定的增温影响,合阳国道对环境温度的增温影响至75m,增温效应达0.25~0.4℃。高速公路的增温影响至125m,增温效应达0.2~0.4℃。冬季,两条公路白天增温效应较夜间明显,春季,高速公路夜间增温更明显。晴天、多云天气比阴天、降雨天气增温程度大。公路对气温的增温影响存在风速阈值,当风速小于对应阈值时,增温效应明显。公路上来往车流量对气温有一定的叠加增温影响,合阳国道白天车流量150~350辆,叠加增温效应0.05~0.1℃,蒲渭高速白天车流量2000~3500辆,叠加增温效应0.16℃。  相似文献   
22.
Aerial photographs taken in 1978 and 1987, Landsat TM images in 1998 as well as soil, hydrology and socio-economic data for the oases in Sangong River Watershed were processed by Remote Sensing (RS) and Geographic Information System (GIS). There are two typical agricultural land uses in oases, Farm-based Land Use with large-scale intensified agricultural activities (FLU) and Household Responsibility-based Land Use with small-scale activities (HRLU). The Index Model of Land Use/Land Cover Change (LUCC), Weighted Index Sum (WIS) and logistic stepwise regression model were established to contrast the two typical LUCC processes and their driving forces. The land use patterns were dominated by cropland and grassland for the entire region, and cropland, residential and industrial land were increasing stably. In the HRLU areas, woodland and grassland declined dramatically, but in the FLU areas, grassland decreased only by 12.0%, whereas woodland increased by 13.7%. LUCC was stronger in the earlier stage (1978–1987) than in the later stage (1987–1998) for the entire region. LUCC was more intense in the HRLU areas than in the FLU areas during the entire period (1978–1998). Policy was a key factor in the land use change, and water resources were a precondition in land use. Under the control of policy and water resources, the main human driving factors included population and economy, and the main natural restrictions were soil fertility and groundwater depth. Human driving factors controlled the land change in the HRLU areas, but natural restriction factors dominated in the FLU areas. In the mean time, intensification of LUCC in the region had some spatiotemporal implications with a fluctuation of impact factors.  相似文献   
23.
This paper demonstrates the plausibility of inferring the spatial variability of geology from topographically derived landscape dissection patterns. This enables surveying large regions for spatial variability in geology, for which direct remote sensing is not feasible, by studying variability in dissection pattern, a feature extracted straight off from digital elevation model data. Dissection pattern is obtained automatically by a novel algorithm, especially designed to delineate the valleys with high accuracy in order to reflect spatial variability in dissection density. The dissection pattern is encapsulated by a continuous map of drainage density, a raster variable best suited for showing spatial variability of dissection. Such a map, constructed for the study area in the Cascade Range, Oregon, USA, shows a sharp discontinuity in the dissection pattern, indicating change in underlying geology. Possible factors controlling the dissection pattern such as climate, local and regional slopes, vegetation, and geology are examined, and geology has been found to be the dominant controlling factor. The dissection contrast coincides with the boundary between the Western and High Cascades, two geologic provinces with different rock ages and types. The older and less permeable Western Cascades are associated with denser dissection pattern, whereas the younger and more permeable High Cascades correspond to less dissected pattern. This new mapping method can be applied to locations where topography is the only readily available data, and the generated map could be used to extract previously unknown geologic or environmental information.  相似文献   
24.
25.
因基阵各通道不均衡,使得水声接收系统波束形成时,目标检测、方位估计等性能经常达不到预期。分析了各通道信噪比、辐值、相位影响波束信噪比的机理,提出了一种减小基阵各通道不均衡的方法,并利用实测数据进行了仿真。仿真结果表明:该方法可有效地提高水声接收系统的目标检测、方位估计等性能。  相似文献   
26.
新一代区域海-气-浪耦合台风预报系统   总被引:1,自引:0,他引:1  
依托国家重点基础研究(973)计划项目"上层海洋对台风的响应和调制机理研究",中国气象局上海台风研究所联合国家海洋局的相关单位,通过实施近海台风的外场观测科学试验、加强台风边界层(特别是海气相互作用)物理过程诊断分析及参数化方案等的研究,建立并改进了台风强度预报的海-气-浪耦合预报模式系统,并在此基础上发展了台风强度的集合预报技术,在历史典型台风个例和2016-2017年台汛期的业务化测试中表现出良好的预报性能。  相似文献   
27.
<正>10年时间尺度的气候预测,由于能够提供给政策制定者和有关部门与单位近期的气候变化预测,作为经济规划和社会生活安排等的参考,因此越来越受到重视。10年气候预测是气候科学中一个新的领域,一般预测方法采用:一是统计预测方法,根据前期气候变化特征,利用统计关系,计算预测未来10年的气候变化;二是动力模式预测方法,利用全球或区域气候模式,在一定初边条件和外强迫作用下,预测未来10年的气候变化;三是动力加统计  相似文献   
28.
On the Use of CloudSat and MODIS Data for Estimating Hurricane Intensity   总被引:2,自引:0,他引:2  
This letter presents preliminary results concerning the use of new observations from the A-Train Constellation for testing a new technique of remotely sensing hurricane intensity from space based on modeling a hurricane as a balanced, convectively neutral vortex. The key observational requirements are simultaneous, accurate measurements of cloud-top height, cloudtop temperature, and cloud profiling information across the center of the storm, although there are ways to bypass the need for cloud-top temperature. In this letter, the Moderate Resolution Imaging Spectroradiometer onboard Aqua provides an estimation of the cloud-top temperature, and the near-simultaneous CloudSat observations provide the essential cloud-top height and cloud profiling information. Initial results indicate that the new technique is a promising method for estimating storm intensity when compared post facto to the best track database. Potential uncertainties and room for further refinement of the technique are discussed.  相似文献   
29.
Lengshuiqing is part of the late Proterozoic igneous province from the western margin of the Yangtze craton. The Lengshuiqing area comprises five ultramafic–mafic intrusions, emplaced in the late Proterozoic Yanbian Group. The intrusions from Lengshuiqing contain cumulate ultramafic zones (peridotite + olivine pyroxenite), with cumulus olivine and Cr-spinel, and intercumulus pyroxenes, hornblende, phlogopite and plagioclase. Ni–Cu ore (pyrrhotite + pentlandite + chalcopyrite) is hosted in the ultramafic zones. Olivine-free diorite–quartz diorite ± gabbro and granite zones commonly occur above the ultramafic rocks. The genesis of the intrusions (conduit-related accumulation or differentiation from stagnant magma) was investigated. The amount of sulphides in the intrusions from Lengshuiqing is one order of magnitude bigger than the sulphides that can be dissolved by a volume of mafic magma similar with the volume of the intrusions. Most intrusions from Lengshuiqing have bulk composition (peridotite ± diorite ± granite) more magnesian (MgO = 21–22%; Mg# > 78) than the deduced composition of their parental magma (MgO = 9–11%; Mg# = 64–67). This indicates the accumulation of sulphide and mafic silicates from a volume of magma much bigger than the volume of the intrusions, which can be explained by the fractionation from magma ascending through the intrusions to shallower depths. A continuous supply and vent of magma is consistent with the lack of chilled margins, the melting of the wall rocks and the generation of high-temperature mineral assemblages (K-feldspar, diopside, and sillimanite) in the Yanbian Group. The intrusions from Lengshuiqing are seen as microchambers on conduits draining olivine-, Cr-spinel-, and sulphide-bearing mafic magma from a larger staging chamber.  相似文献   
30.
INTRODUCTIONTheattentiontothestudyofmetalsinthemarineaerosolparticulatesisincreasingduetotheirenvironmentalecologicaleffectsandcontributiontothebiogeochemicalcycle.Intheaspectofenvironmentalecologicaleffects,first,onthesideofclimate,aerosolswithmetalscanactascloudcondensationoricenuclei,absorbandscattersolarradiation,andaffecttheradiationbudgetontheearth.Therelativelyhighironcontent(5%)ofthedustcanabsorbtheshortwavelengthradiationefficiently.Second,onthesideofecologicaleffects,di~lvedAlse…  相似文献   
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