Sensitivities of tornadogenesis to drop size distribution in a simulated subtropical supercell over eastern China   总被引：2，自引：0，他引：2  

ZHENG Kailin  CHEN Baojun 《大气科学进展》2014,31(3):657-668

ABSTRACT Numerical simulations with the Advanced Regional Prediction System （ARPS） model were performed to investigate the impact of microphysical drop size distribution （DSD） on tornadogenesis in a subtropical supercell thunderstorm over Anhui Province, eastern China. Sensitivity experiments with different intercept parameters of rain, hail and snow DSDs in a Lin-type microphysics scheme were conducted. Results showed that rain and hail DSDs have a significant impact on the simulated storm both microphysically and dynamically. DSDs characterized by larger （smaller） intercepts have a smaller （larger） particle size and a lower （higher） mass-weighted mean fall velocity, and produce relatively stronger （weaker） and wider （narrower） cold pools through enhanced （reduced） rain evaporation and hail melting processes, which are then less favorable （favorable） for tornadogenesis. However, tornadogenesis will also be suppressed by the weakened mid-level mesocyclone when the cold pool is too weak. When compared to a U.S. Great Plain case, the two microphysical processes are more sensitive to DSD variations in the present case with a higher melting level and deeper warm layer. This suggests that DSD-related cloud microphysics has a stronger influence on tornadogenesis in supercells over the subtropics than the U.S. Great Plains.  相似文献   

Aridity in Vojvodina, Serbia   总被引：2，自引：1，他引：1  

Ivana Hrnjak  Tin Lukić  Milivoj B. Gavrilov  Slobodan B. Marković  Miroslava Unkašević  Ivana Tošić 《Theoretical and Applied Climatology》2014,115(1-2):323-332

For investigating aridity in Vojvodina, two parameters were used: the De Martonne aridity index and the Pinna combinative index. These indices were chosen as the most suitable for the analysis of climate in Vojvodina (a region in northern part of Serbia). Also, these indices were calculated from data obtained from 10 meteorological stations for the period from 1949 to 2006. The spatial distribution of the annual and seasonal De Martonne and the Pinna combinative indices as well as the mean monthly values of the De Martonne index and aridity trends of these indices are presented. There were two, four, and five types of climate on a yearly, seasonal, and monthly basis in Vojvodina, according to the De Martonne climate classification which consists of a total of seven types. In addition, semi-humid and humid climate types were represented in the region, on a yearly basis. The winter season was dominated by wetter types of climate, while the summer season was characterized by drier ones. During the spring and autumn seasons, there were types of climate which range between both aforementioned types. Two out of three climate types, which can be identified using the Pinna combinative index, were registered in Vojvodina region. The most dominant climate type was the semidry Mediterranean with formal Mediterranean vegetation, while the humid type was only identified in one small part of southwestern Vojvodina. The calculated values of both aridity indices showed that there were no annual trends. Therefore, it can be considered that there were no recent aridity changes during the observed period. For paleoclimate, the general story is more complex. The lack of aridity trends in the recent period from 1949 to 2006 supports the fact that Vojvodina has very well preserved loess–palaeosol sequences from the Middle and Late Pleistocene, which indicates that crucial point for their preservation was caused by the weak aridity variability in the region.  相似文献   

Temporal and spatial changes of the basal channel of the Getz Ice Shelf in Antarctica derived from multi-source data     

Zemin Wang  Mingliang Liu  Baojun Zhang  Xiangyu Song  Jiachun An 《海洋学报(英文版)》2022,41(9):50-59

Basal melting is an important factor affecting the stability of the ice shelf. The basal channel is formed from uneven melting, which also has an important impact on the stability of the ice shelf. Therefore, it has important scientific value to study the basal channel changes. This study combined datasets of Mosaics of Antarctica, Reference Elevation Model of Antarctica (REMA) and Operation IceBridge to study the temporal and spatial changes of basal channels at the Getz Ice Shelf in Antarctica. The relationships between the cross-sectional area and width of basal channel and those of its corresponding surface depression were statistically analyzed. Then, the changes of the basal channels of Getz Ice Shelf were derived from the ICESat observations and REMA digital elevation models (DEMs). After a detailed analysis of the factors affecting the basal channel changes, we found that the basal channels of Getz Ice Shelf were mainly concentrated in the eastern of the ice shelf, and most of them belonged to the ocean-sourced basal channel. From 2009 to 2016, the total length of the basal channel has increased by approximately 60 km. Affected by the warm Circumpolar Deep Water (CDW), significant changes in the basal channel occurred in the middle reaches of the Getz Ice Shelf. The change of the basal channels at the edge of the Getz Ice Shelf is significantly weaker than that in its middle and upper reaches. Especially in 2005–2012, the eastward wind on the ocean wind field and the westward wind around the continental shelf caused the invasion and upwelling of CDW. Meanwhile, the continuous warming of deep seawater also caused the deepening of the basal channel. During from 2012 to 2020, the fluctuations of the basal channels seem to be caused by the changes in temperature of CDW.  相似文献   

Geographical Detectors‐Based Health Risk Assessment and its Application in the Neural Tube Defects Study of the Heshun Region,China     

Jin‐Feng Wang  Xin‐Hu Li  George Christakos  Yi‐Lan Liao  Tin Zhang  Xue Gu 《International journal of geographical information science》2013,27(1):107-127

Physical environment, man‐made pollution, nutrition and their mutual interactions can be major causes of human diseases. These disease determinants have distinct spatial distributions across geographical units, so that their adequate study involves the investigation of the associated geographical strata. We propose four geographical detectors based on spatial variation analysis of the geographical strata to assess the environmental risks of health: the risk detector indicates where the risk areas are; the factor detector identifies factors that are responsible for the risk; the ecological detector discloses relative importance between the factors; and the interaction detector reveals whether the risk factors interact or lead to disease independently. In a real‐world study, the primary physical environment (watershed, lithozone and soil) was found to strongly control the neural tube defects (NTD) occurrences in the Heshun region (China). Basic nutrition (food) was found to be more important than man‐made pollution (chemical fertilizer) in the control of the spatial NTD pattern. Ancient materials released from geological faults and subsequently spread along slopes dramatically increase the NTD risk. These findings constitute valuable input to disease intervention strategies in the region of interest.  相似文献   

北涡南槽形势下的辽宁降水性质分析   总被引：1，自引：1，他引：0  

沈玉敏  陈宝君  吴曼丽  韩江文  孙欣 《气象科学》2008,28(3):348-353

2005年4月6日、19日辽宁省出现了两次降水天气过程.通过资料显示,这两场降水的影响系统,虽然都主要是北涡南槽的天气系统(这里的北涡南槽是指,由蒙古至贝加尔湖低涡和河套地区东部的高空槽以及槽前的西南气流组合的耦合系统).但是由于具体影响的物理因子的不同,所以产生的降水性质也不同.6日的降水是不稳定的雷阵雨天气,是由中小尺度不稳定雷雨云团与东北西部东移的低压冷锋相结合的物理过程;19日是以稳定性降水为主,伴有阵雨、雷阵雨的混合性降水天气,是由东移的蒙古低涡与河套地区东部高空槽相结合的物理过程.  相似文献   

城市热岛效应对土体工程性质的影响及其关键科学问题   总被引：2，自引：1，他引：1  

施斌  邵玉娴  刘春  王宝军 《工程地质学报》2009,17(2):180-187

随着全球气候变暖、城市化进程加快,世界各地大城市的热岛效应及其带来的各种环境和生态问题越来越严重。本文从地质环境保护的角度,分析了城市热岛效应的成因、特点及其对地质环境的影响,重点讨论了城市热岛效应环境中土体工程性质的变化及其带来的各种灾害效应,在此基础上,凝练出了4个关键科学问题,即城市热岛效应环境中土体温度场变化规律、土体中水分迁移规律、土体工程性质变化规律以及土体地质灾害效应,并对它们的具体研究内容进行了详细的分析。论文的分析成果对于掌握城市热岛效应对土体工程性质的影响,保护城市地质环境和防灾减灾,实现城市的可持续发展具有重要的理论和现实意义。   相似文献   

The Research Status and Development Trends of Wind-Sand Engineering in China   总被引：2，自引：1，他引：1  

Jianjun Qu  Yuquan Ling  Baojun Liu  Guangting Chen  Tao Wang  Zhibao Dong 《地球科学进展》2019,34(3):225-231

The concept and category of wind-sand engineering were discussed in this paper. The development processes of wind-sand engineering in China were reviewed preliminarily. Based on different regional environments, wind-sand engineering research in our country can be divided into two parts: aeolian research of major engineering in desert areas, and aeolian research of major engineering in other areas with special environment. Further than that, aeolian research of major engineering in desert areas can be divided into 4 stages, and aeolian research of major engineering in other areas with special environment mainly focuses on tropical coastal areas, Tibet Plateau and gobi in arid areas. Our research suggests that the development trends of major wind-sand engineering can be summarized as the following aspects. \mathrm{①} Revealing principles of the wind-sand engineering shelter systems; \mathrm{②} Evaluating environmental effects of the major wind-sand engineering; \mathrm{③} Functions of the wind-sand engineering transforming from simple sand prevention to eco-economic types shelter systems; \mathrm{④} A kind of treatment technology with fabricated materials and equipped construction processes needs to be studied urgently, which can make sand prevention with rapid pace, high efficiency and high quality.  相似文献   

冰雹云中累积区与冰雹的形成的数值模拟研究   总被引：32，自引：8，他引：24  

周玲  陈宝君  李子华  黄美元  郭学良  肖辉  洪延超 《大气科学》2001,25(4):536-550

应用三维冰雹云模式对陕西旬邑地区的一次降雹过程进行模拟,结果表明:冰雹云中存在过冷雨水的累积区,其出现在最大上升气流之上,其中累积的过冷雨水含量随着云的发展而变化.冰雹生长在此累积区内.催化试验结果表明,在过冷雨水的累积区内播撒AgI粒子能取得较好的防雹效果.  相似文献   

中国南方早古生代碳酸盐台地形成与发展   总被引：1，自引：0，他引：1       下载免费PDF全文

徐强  刘宝珺  许效松 《沉积与特提斯地质》1996,16(4):1-5

中国南方碳酸盐台地从震旦纪到志留纪十分发育，它对认识中国南方沉积地壳演化和油气勘探具有重要意义。９０年代以来，中国南方碳酸盐台地从台地内部结构研究发展到对碳酸盐台地边缘、台地几何形态、台地边缘形态的研究，并把它们的形成和演化与大地构造、全球海平面变化、沉积层序、动力演化过程结合起来，进行碳酸盐台地发展、演化、沉降、生长的定量模拟、此外，还特别重视重大地质事件和非现实主义沉积作用探索。中国南方早古生代碳酸盐台地，随着扬子板块的裂谷拉张、被动大陆边缘构造热沉降和前陆挠曲，经历了碳酸盐台地产生、发展和消亡的完整威尔逊旋回动力演化、最终这个巨大的碳酸盐台地因挠曲沉降淹没和大量碎屑岩覆盖而消亡，是具有非常良好远景的油气资源探区。  相似文献   

固体中非线性纵波一维数值模拟   总被引：2，自引：0，他引：2       下载免费PDF全文

郑海山  张中杰  杨宝俊 《地震学报》2004,26(1):77-83

分别采用四阶精度和六阶精度的中心差分格式，限定扰动（振幅）的取值在10-3m以内，进行了一维固体中非线性纵波传播的数值模拟，并通过两种格式对比性研究来保证差分格式的稳定性和收敛性．讨论了边界所输入正弦波的振幅、频率及介质非线性系数对非线性波的影响．模拟结果与位于生存周期之内近似解析解相符，并证实非线性波在传播过程中会发生波形畸变、产生倍频效应及谐波能量积累，而且这些非线性波动特征随输入振幅、频率和介质非线性系数（绝对值）的增大而增强．   相似文献