天然浮游动物在真鲷育苗中应用技术的研究   总被引：3，自引：0，他引：3  

孙光  柳志会  王荣中  王宝利  段钰 《海洋科学》1992,16(5):29-33

研究了大量采集天然浮游动物并将其应用于真鲷育苗生产的技术,探讨了真鲷仔稚鱼对饵料生物的选择性,开辟了鱼类育苗新饵源,可摆脱目前过多依赖卤虫卵的局面。结果表明,全部或混合投喂浮游动物与全部投喂卤虫幼体相比,真鲷仔稚鱼成活率提高31.9～34.4％,饵料成本降低15.2～28.8％,而且仔稚鱼活力强、无畸形,生长较整齐。  相似文献   

南海夜光藻赤潮概况及其对水文气象的适应条件     

吴瑞贞  林端  马毅 《台湾海峡》2007,26(4):590-595

本文根据1980~2004年的南海历次夜光藻赤潮事件资料,对这些赤潮事件在时间和空间的分布特征以及赤潮持续时间进行了分析;发现了夜光藻赤潮在1996年后被其它种类赤潮所更替的现象,并初步探讨其原因;统计、分析了夜光藻赤潮发生前后水文气象要素的变化范围和演变特征,提出了南海夜光藻赤潮的适温范围.  相似文献   

Estimation of ground heat flux from soil temperature over a bare soil   总被引：1，自引：0，他引：1  

Kedong?An  Wenke?WangEmail author  Zhoufeng?Wang  Yaqian?Zhao  Zeyuan?Yang  Li?Chen  Zaiyong?Zhang  Lei?Duan 《Theoretical and Applied Climatology》2017,129(3-4):913-922

Ground soil heat flux, G ₀, is a difficult-to-measure but important component of the surface energy budget. Over the past years, many methods were proposed to estimate G ₀; however, the application of these methods was seldom validated and assessed under different weather conditions. In this study, three popular models (force-restore, conduction-convection, and harmonic) and one widely used method (plate calorimetric), which had well performance in publications, were investigated using field data to estimate daily G ₀ on clear, cloudy, and rainy days, while the gradient calorimetric method was regarded as the reference for assessing the accuracy. The results showed that harmonic model was well reproducing the G ₀ curve for clear days, but it yielded large errors on cloudy and rainy days. The force-restore model worked well only under rainfall condition, but it was poor to estimate G ₀ under rain-free conditions. On the contrary, the conduction-convection model was acceptable to determine G ₀ under rain-free conditions, but it generated large errors on rainfall days. More importantly, the plate calorimetric method was the best to estimate G ₀ under different weather conditions compared with the three models, but the performance of this method is affected by the placement depth of the heat flux plate. As a result, the heat flux plate was recommended to be buried as close as possible to the surface under clear condition. But under cloudy and rainy conditions, the plate placed at depth of around 0.075 m yielded G ₀ well. Overall, the findings of this paper provide guidelines to acquire more accurate estimation of G ₀ under different weather conditions, which could improve the surface energy balance in field.  相似文献   

Reducing the prediction uncertainties of high-impact weather and climate events: An overview of studies at LASG          下载免费PDF全文

Wansuo Duan  Rong Feng 《Acta Meteorologica Sinica》2017,31(1):224-235

This paper summarizes recent progress at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences in studies on targeted observations, data assimilation, and ensemble prediction, which are three effective strategies to reduce the prediction uncertainties and improve the forecast skill of weather and climate events. Considering the limitations of traditional targeted observation approaches, LASG researchers have developed a conditional nonlinear optimal perturbation-based targeted observation strategy to optimize the design of the observing network. This strategy has been employed to identify sensitive areas for targeted observations of the El Niño–Southern Oscillation, Indian Ocean dipole, and tropical cyclones, and has been demonstrated to be effective in improving the forecast skill of these events. To assimilate the targeted observations into the initial state of a numerical model, a dimension-reducedprojection- based four-dimensional variational data assimilation (DRP-4DVar) approach has been proposed and is used operationally to supply accurate initial conditions in numerical forecasts. The performance of DRP-4DVar is good, and its computational cost is much lower than the standard 4DVar approach. Besides, ensemble prediction, which is a practical approach to generate probabilistic forecasts of the future state of a particular system, can be used to reduce the prediction uncertainties of single forecasts by taking the ensemble mean of forecast members. In this field, LASG researchers have proposed an ensemble forecast method that uses nonlinear local Lyapunov vectors (NLLVs) to yield ensemble initial perturbations. Its application in simple models has shown that NLLVs are more useful than bred vectors and singular vectors in improving the skill of the ensemble forecast. Therefore, NLLVs represent a candidate for possible development as an ensemble method in operational forecasts. Despite the considerable efforts made towards developing these methods to reduce prediction uncertainties, much challenging but highly important work remains in terms of improving the methods to further increase the skill in forecasting such weather and climate events.  相似文献   

Assimilation of <Emphasis Type="Italic">HY-2A</Emphasis> scatterometer ambiguous winds based on feature thinning     

Boheng Duan  Weimin Zhang  Xiaoqun Cao  Yi Yu  Haijin Dai 《Acta Meteorologica Sinica》2017,31(4):720-730

This paper focuses on the data assimilation methods for sea surface winds, based on the level-2B HY-2A satellite microwave scatterometer wind products. We propose a new feature thinning method, which is herein used to screen scatterometer winds while maintaining the key structure of the wind field in the process of data thinning for highresolution satellite observations. We also accomplish feeding the ambiguous wind solutions directly into the data assimilation system, thus making better use of the retrieved information while simplifying the assimilation process of the scatterometer products. A numerical simulation experiment involving Typhoon Danas shows that our method gives better results than the traditional approach. This method may be a valuable alternative for operational satellite data assimilation.  相似文献   

我国农业土地规模经营模式研究——基于西方资本主义雇佣型大农场的衰落及启示     

段禄峰  魏明 《地域研究与开发》2017,36(1)

随着城镇化的快速推进,我国农村人口不断减少,土地经营模式正发生着根本性变革。以提高农业土地经营效益为目的,采用文献统计和比较分析等研究方法,通过分析西方资本主义雇佣型大农场的衰落历程及原因,提出在我国当前人均耕地面积较少、就业压力较大的情况下,实施家庭承包经营、雇佣型大农场以及家庭农场并行的土地经营模式,最终实现家庭农场主导经营模式。研究结果表明:耕者有其田的家庭农场模式可以促进更多就业,避免马尔萨斯-李嘉图危机,有利于财富的公平分配和社会稳定。  相似文献   

基于暴雨内涝模型的莆田沿海地区风暴潮灾害评估     

陈靖  解以扬  张容焱  李培彦  严平勇  段丽瑶  邱晓滨  王雪莲 《气象科技》2017,45(2):390-397

利用ArcGIS对莆田沿海地区的地形、下垫面属性和排水设施及排水运作方式进行预处理,建立台风降水、风暴潮共同影响下的莆田沿海地区内涝模型。应用雷达估算降水及自动雨量站数据计算的热带气旋"南玛都"过程面雨量,以及此次暴雨过程沿岸海区和河口的时变水位作为模型的边界条件,对莆田地区风暴潮灾害风险进行评估试验。针对2011年9月1日热带气旋"南玛都"造成的莆田沿海地区风暴潮及暴雨灾害,利用暴雨内涝模型进行评估试验研究,将模拟结果与实况灾情进行对比,结果表明模型能够较客观地反映"南玛都"过程降水和风暴潮共同作用的灾害情况。  相似文献   

闪电数据三维可视化统计分析系统设计与实现     

朱传林  王学良  范宏飞  柴健  余蓉  汪姿荷 《气象科技》2017,45(1):59-63

利用虚拟仿真技术,基于GaeaExplorer三维地理信息系统平台,设计开发了闪电数据三维可视化与统计分析系统。建立了闪电空间数据库,搭建了逼真的三维仿真场景,实现了闪电数据三维精细可视化;同时结合地理信息系统的空间分析能力,实现了闪电数据的管理及空间分析功能,为防雷减灾和决策服务提供了科学手段。应用结果表明:研发的闪电数据三维可视化与统计分析系统具有良好的应用体验,为闪电业务及科研工作提供了坚实的基础平台。  相似文献   

河南承接制造业转移的时空格局研究   总被引：1，自引：1，他引：0  

段小薇  苗长虹  赵建吉 《地理科学》2017,37(1):72-82

基于2000~2009年中国大中型企业数据库数据,利用产业转移承接指数、地区专业化和多样化指数、改进的偏离份额分析等方法,从时间、空间以及行业-区位等维度对河南承接制造业产业转移的时空格局进行研究。结果表明：① 时间趋势上,河南承接国内外制造业转移规模持续增大,承接行业类型显著增多;轻工业比重高于重工业,资本密集型行业明显增加。② 空间格局上,基本呈现出以中原城市群为中心的核心-外围模式,豫北地区承接制造业转移规模逐渐降低,而黄淮地区显著增强。各地市在制造业总体、轻工业、重工业以及劳动密集型、资本密集型和技术密集型行业的承接上,呈现出增强型、减弱型、补缺型、抵消型等不同的特征;专业化和多样化承接的组合类型城市之间也明显不同,地市间承接制造业转移的行业存在雷同,但多数转移行业受地理临近性的影响不显著。③ 行业-区位组合上,劳动密集的轻工业和资本密集的重工业的集聚效应非常明显,而技术密集型行业对区位优势的指向性很强。  相似文献   

生物标志化合物碳同位素地球化学研究的几个相关问题   总被引：6，自引：0，他引：6  

段毅  马兰华 《地球科学进展》1996,11(4):356-361

生物标志化合物稳定碳同位素地球化学是８０年代末期新兴的研究领域。单个生物标志化合物碳同位素组成的成因解释是该领域至关重要的问题。本文综合讨论了与此有关的生物合成过程中脂类化合物碳同位素变化、细菌生物合成过程中碳同位素分馏及其脂类化合物碳同位素组成特征，从而为我国的生物标志化合物碳同位素地球化学研究提供了新的理论依据  相似文献