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利用地面气象常规观测资料、区域自动站观测资料、雷达及卫星资料和NCEP 1°×1°的逐6h再分析资料,对2018年5月13日攀西地区南部的飑线天气过程的形成机制进行分析。结果表明:飑线发生在高空槽前,高空槽逐渐东移推动冷性气流沿背风坡东移,然后与前方低层暖空气汇合抬升形成对流;露点锋触发了飑线天气过程的形成;产生飑线天气区域的大气具有上干下湿、不稳定能量高、垂直风切变强、高层风速大和形成之前存在逆温层的特点;高空急流和动量下传对飑线的发生和加强具有促进作用;地形对飑线的形成和天气现象的分布有影响。 相似文献
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石炭纪是地质演化历史上重要的时期,发生了全球规模的海西造山运动,晚古生代大冰期（LPIA）达到峰值,全球海平面频繁波动,导致古气候和古环境的剧烈变化。在华南,石炭纪中期,浅水碳酸盐岩台地相区广泛发育一套白云岩沉积。本文系统总结华南3个主要碳酸盐台地内白云岩的厚度及时代,识别出白云岩时空分布的差异性。结合石炭纪中期全球气候环境特征,认为冰期兴盛引发了全球海平面下降,导致华南各沉积盆地形成利于白云岩化的环境,白云岩得以发育。而白云岩时空分布的差异性可能与各沉积盆地独特的构造演化以及不同成岩模式有关。中下扬子碳酸盐岩台地白云岩的形成模式主要为萨勃哈模式和成岩早期浅埋藏的渗透回流模式,形成相对较薄的白云岩沉积;中南部和西南部碳酸盐岩台地白云岩的形成模式为渗透回流模式,成岩规模较大,沉积较厚。 相似文献
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The ECMWF has been assimilating Feng-Yun-3B(FY-3B) satellite microwave humidity sounder(MWHS) data over ocean in an operational forecasting system since 24 September 2014. It is more difficult, however, to assimilate microwave observations over land and sea ice than over the open ocean due to higher uncertainties in land surface temperature, surface emissivity and less effective cloud screening. We compare approaches in which the emissivity is retrieved dynamically from MWHS channel 1 [150 GHz(vertical polarization)] with the use of an evolving emissivity atlas from 89 GHz observations from the MWHS onboard NOAA and EUMETSAT satellites. The assimilation of the additional data over land improves the fit of short-range forecasts to other observations, notably ATMS(Advanced Technology Microwave Sounder) humidity channels, and the forecast impacts are mainly neutral to slightly positive over the first five days. The forecast impacts are better in boreal summer and the Southern Hemisphere. These results suggest that the techniques tested allow for effective assimilation of MWHS/FY-3B data over land. 相似文献
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Wang Xiangdong Hu Keyi Qie Wenkun Sheng Qingyi Chen Bo Lin Wei Yao Le Wang Qiulai Qi Yuping Chen Jitao Liao Zhuoting Song Junjun 《中国科学:地球科学(英文版)》2019,62(1):135-153
The Carboniferous period lasted about 60 Myr, from ～358.9 Ma to ～298.9 Ma. According to the International Commission on Stratigraphy, the Carboniferous System is subdivided into two subsystems, i.e., Mississippian and Pennsylvanian, including 6 series and 7 stages. The Global Stratotype Sections and Points(GSSPs) of three stages have been ratified, the Tournaisian, Visean, and Bashkirian stages. The GSSPs of the remaining four stages(i.e., the Serpukhovian, Moscovian,Kasimovian, and Gzhelian) have not been ratified so far. This paper outlines Carboniferous stratigraphic subdivision and correlation on the basis of detailed biostratigraphy mainly from South China, and summarizes the Carboniferous chronostratigraphic framework of China. High-resolution biostratigraphic study reveals 37 conodont zones, 24 foraminiferal(including fusulinid) zones, 13 ammonoid zones, 10 brachiopod zones, and 10 rugose coral zones in the Carboniferous of China. The biostratigraphic framework based on these biozones warrants the precise correlation of regional stratigraphy of China(including2 subsystems, 4 series, and 8 stages) to that of the other regions globally. Meanwhile, the Carboniferous chemo-, sequence-,cyclo-, and event-stratigraphy of China have been intensively studied and can also be correlated worldwide. Future studies on the Carboniferous in China should focus on(1) the correlation between shallow-and deep-water facies and between marine and continental facies,(2) high-resolution astronomical cyclostratigraphy, and(3) paleoenvironment and paleoclimate analysis based on geochemical proxies such as strontium and oxygen isotopes, as well as stomatal indices of fossil plants. 相似文献
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一种新的有限区域曲面拟合方法 总被引：2，自引：0，他引：2
本文提出一种在有限区域内对物理量进行曲面拟合的新方法(NMOCSF),该法根据滤波原理进行多重拟合,每次拟合时,拟合函数的最大、最小值点位置与原函数的一致。对比试验表明,NMOCSF的拟合精度比有限元法高,能够分辨出尺度为220km左右的天气系统,且拟合函数在计算区域内连续、光滑、方法稳定。因此在诊断分析中的实际使用价值高于有限元法。 相似文献
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RS-485总线理论的应用与分析 总被引：2，自引：0，他引：2
本文简要介绍了 RS- 4 85理论 ,对在实际应用中的 RS- 4 85网络配置、总线匹配、传输距离、抗干扰措施等做了详细的说明。给出了 1个实际的应用系统 ,阐述了组网时应注意的几个问题 相似文献
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早前寒武纪克拉通过去认为是地槽演化的结果。其实不然。本文讨论形成它们变质原岩火山－沉积建造的大地构造条件。现成早前寒武纪克拉通火山沉积盖层的成熟沉积岩丰富了孔兹岩原岩。它们面状展布，经常是很长时期形成的，这改进了识别早前寒武纪克拉通地台式变质原岩建造的标志。这类标志遍及七大洲，高级区和绿岩带。有理由认为，早前寒武纪克拉通是在老克拉通盆地里的地台式火山－沉积建造经变质－混合岩化－塑性流变－硬化的产物。 相似文献
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通过“面拟合物理蛳诊断和三维图形显示系统”获得适合华东区域使用的多种物理量咕维图形，摸索用立体图形制作天然气预报的着眼点，初步分析表明物理量立体图是有非常广阔应用前景的工具之一。 相似文献