C-FMCW雷达对江淮降水云零度层亮带探测研究

不同于体扫雷达探测降水系统,垂直指向雷达可探测降水云中粒子垂直演变的微物理过程。C波段调频连续波垂直指向雷达 (C-FMCW) 采用收发分置天线,数据垂直分辨率达15~30 m,时间分辨率达2~3 s,利用其2013年6—8月在安徽定远探测数据对降水云垂直结构特征及亮带中融化微物理过程进行研究。6次降水过程共计46 h中的39.1%数据具有清晰的亮带结构特征,期间降水占地面总降水量的15%;江淮雨季层状云、对流云和混合性降水系统中均出现零度层亮带,层状云中亮带长时间维持,对流降水系统移出后减弱阶段的亮带结构稳定,混合降水系统中的对流扰动加强冲破了亮带结构。以融化层中最大回波强度Z_p所在高度进行融化层的粒子碰并增长和破碎减弱分层分析,上半层融化过程主要表现为碰并增长,下半层则是粒子破碎减弱。剔除了介电常数、下降速度引起的粒子浓度改变影响后,层状云和对流降水后期的回波强度加强表明融化增长程度接近,后者略强,混合降水云的融化增长最强。     

Vegetation of Mangroves： Spatial and Temporal Pattern of itsDominant Populations in Futian National Nature Reserve

The community characteristics of mangroves in the Futian Nature Reserve,Shenzhen, China are given based on surveying of 33 quadrats in 4 transects which stretch from the higher tidal zone to the lower tidal zone. The results show that there are 6 community types in this area: Kandelia candel association, Avicennia marina association, A egiceras corniculatum association, Kandelia candel Aegiceras corniculatum association,degiceras corniculatum Kandelia candel association and Acanthus ilicifolius association.Kandelia candel, degiceras corniculatum and dvicennia marina dominate the typicalquadrats. Kandelia candel can be seen at almost all quadrats, Aegiceras corniculatumdistributes mostly toward the estuary and the higher tidal zone, Avicennia marina distributesmostly toward the bay and the lower tidal zone, Bruguiera gymnorrhiza occasionally occurs toward the Estuary with one or several individuals, Acanthus ilicifolius was common towardthe higher tidal zone, as an accompanying species, Derris trifoliata was common in manymature ouadrats. Totallv. 6 snecies of man~rove plants and 3 soecies of semi-mangrove plants appear in this research area. From the higher tidal zone to the lower tidal zone, the average diameter and basal area of mangrove trees increase gradually. According to the results, the dvicennia marina dominates in average diameter and basal area, and the degicerascorniculatum trees are on the contrary. From the transect ! to the transect 4, the importance value ot dvicennia marina, Bruguiera gymnorrhiza and Kandelia candel decreases, and degiceras corniculatum increases. In this area, the Kandelia candel population and Ae giceras corniculatum population are developing populations with many seedlings and saplings, but the Avicennia marina population is in a mature stage with few seedlings and not so many total individuals. According to this research, we suppose that Aegiceras corniculatum should be developed toward the estuary and the dvicennia marina association should be protected.     

台湾海峡海域表观耗氧量之研究

台湾海峡海域1983－1988年多次调查资料表明，该海域夏季表现耗氧量（AOU）变化幅度较大，其分布特征呈近岸、底层高，向上层、外海递减，诸上升流是其主要控制因素。各上升流区AOU与温度、盐度、诸营养盐呈显著相关关系。PO4／AOU与NO3／AOU比值平均分别为0.0058和0.076。上升流海域夏季初始营养盐[PO4,pre和[NO3,pre较低，而再生营养盐高，是现场营养盐的主要部分。有机物质分解耗氧对AOU的贡献比浮游动物等呼吸耗氧更重要。     

The release of phosphorus from sediment into water in subtropical wetlands: a warming microcosm experiment

Global warming poses a great threat to wetland ecological stability and water quality improvement. In this paper, we sampled six types of wetlands representing different kinds of land utilisation around the TaiHu Lake Basin in southeast China. An outdoor computerized microcosm was set up in May 2008 to simulate climate scenarios of ambient temperature (control) and a warmed ambient temperature (+5 °C) using a novel minute‐scale daily and seasonal temperature manipulation technology. The 18‐month incubation indicated that warming impaired the ecological sink of sediment (fixing P from porewater) while strengthening the role of the ecological source, moreover, the rate of P release from sediment into porewater (19–113% for total phosphorus) was much stronger than from top sediment into overlying water. Warming enhanced the activity of neutral and alkaline phosphatases for P‐deficient wetland sediments and neutral phosphatases for P‐rich sediments, at the 14th month of incubation. A significant increase in total phospholipid fatty acids (PLFAs) occurred under warming in sediments with relatively low levels of PLFAs, but bacterial abundance in the sediment biomass tended to decrease (18%) along with an increase (4·5%) of the fungi‐to‐bacteria ratio. The variations of carbon consumption and availability indicated by measured dissolved organic carbon in sediment may have contributed to P release from sediments to water. Copyright © 2011 John Wiley & Sons, Ltd.     

Magnetic Stereoscopy of Coronal Loops in NOAA 8891

The Solar TErrestrial RElations Observatory (STEREO) requires powerful tools for the three-dimensional (3D) reconstruction of the solar corona. Here we test such a program with data from SOHO and TRACE. By taking advantage of solar rotation, a newly developed stereoscopy tool for the reconstruction of coronal loops is applied to the solar active region NOAA 8891 observed from 1 March to 2 March 2000. The stereoscopic reconstruction is composed of three steps. First, we identify loop structures in two TRACE images observed from two vantage viewpoints approximately 17 degrees apart, which corresponds to observations made about 30 hours apart. In the second step, we extrapolate the magnetic field in the corona with the linear force-free field model from the photospheric line-of-sight SOHO/MDI data. Finally, combining the extrapolated field lines and one-dimensional loop curves from two different viewpoints, we obtain the 3D loop structures with the magnetic stereoscopy tool. We demonstrate that by including the magnetic modeling this tool is more powerful than pure geometrical stereoscopy, especially in resolving the ambiguities generated by classical stereoscopy. This work will be applied to the STEREO mission in the near future.     

微型生态系统中鲢、鳙下行影响的实验研究——2.营养物水平

鲢、鳙放养使微型生态系统的水柱氮、磷浓度和磷的分布发生了明显的变化。至实验结束时,各实验组的水柱颗粒磷、总磷和氨氮浓度都比对照组高,而正磷酸盐浓度和沉积物磷的量均低于对照组。这种变化以鳙单养系统为最大,其次是鲢、鳙混养系统,鲢单养系统的变化最小。微型生态系统中正磷酸盐浓度同浮游动、植物密度和初级生产力显著相关,氨氮浓度同所述变量之间的相关关系则多半与正磷酸盐相反。实验观测期间浮游植物密度与总磷浓度之间存在营养级联假说所预见的下行影响,实验结束时二者之间却有上行影响的趋向。根据实验观测结果认为,微型生态系统营养物(尤其是磷)水平的变动,主要是鲢、鳙的摄食改变了系统的群属结构和代谢强度的结果,同时反映了实验鱼对系统中营养物再生的影响。     

Velocity structure of the crust and upper mantle in Xingtai earthquake region and its adjacent area

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