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夜间边界层的一维数值模拟   总被引:1,自引:0,他引:1  
本文用一维数值模式,模拟了平坦地形情况下小风、晴空夜间边界层内风、温、湿的演变,计算结果与观测事实有较好的一致性。对有高云或少量中、低云存在时的计算结果分析表明,模式对风速的模拟仍然较好,对温度的模拟比实测值可偏低0.3—1℃,对相对湿度的模拟比实测值可偏高5—10%在符合模式使用范围的情况下,本模式可作为夜间边界层预报的一种方法参考使用。  相似文献   
2.
蒋瑞宾  张江印 《大气科学》1988,12(3):329-332
本文用一维非定常位温方程,考虑湍流垂直输送和夜间长波辐射冷却作用,导出了晴空夜间逆温层高度的预报方程,并用成都双流机场的实测资料进行了计算.结果表明预报方程的计算结果与实测情况符合较好.  相似文献   
3.
Effect of streambed sediment on benthic ecology   总被引:5,自引:2,他引:3  
Benthic macroinvertebrates have been commonly used as indicator species for assessment of aquatic ecology. Streambed sediment, or substrate, plays an important role in habitat conditions for macroinvertebrate communities. Field investigations were done to study the benthic diversity and macroinvertebrate compositions in various stream substrata. Sampling sites with different bed sediment, latitude, and climate were selected along the Yangtze River, the Yellow River, the East River, and the Juma River, in China. The results show that benthic community structures found in different substrata clearly differ, while those found in substrata of similar composition and flow conditions but in different macroclimates are similar. The study, thus, demonstrates that the benthic macroinvertebrate community is mainly affected by substrate composition and flow conditions, but is generally unaffected by latitudinal position and macroclimate. Taxa richness of the maeroinvertebrate community was found to be the highest on hydrophyte-covered cobbles, high on moss-covered bedrock, and low on clay beds and cobble beds devoid of plant biomass. Sandy beds are compact and unstable, thus, no benthic macroinvertebrates were found colonizing such substrata. Aquatic insects account for most of the macroinvertebrates collected in these rivers. Different insects dominate in different types of substrata: mainly EPT species (Ephemeroptera, Ptecoptera, Tfichoptera) in cobble, gravel, and moss-covered bedrock; and Chironomidae larvae in clay beds. The relation between the number of species in the samples and the size of the sampling area fits a power function of the species area. One square meter (lm) is suggested as the minimum sampling area. A substrate suitability index is proposed by integrating the suitability of sediment, periphyton, and benthic organic materials for macroinvertebrates. The biodiversity of macroinvertebrates increases linearly with the substrate suitability index. Benthic taxa richness increases linearly with the suitability index.  相似文献   
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