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991.
Projection models are commonly used to evaluate the impacts of fishing. However, previously developed projection tools were not suitable for China's fisheries as they are either overly complex and data-demanding or too simple to reflect the realistic management measures. Herein, an intermediate-complexity projection model was developed that could adequately describe fish population dynamics and account for management measures including mesh size limits, summer closure, and spatial closure. A two-patch operating model was outlined for the projection model and applied to the heavily depleted but commercially important small yellow croaker(Larimichthys polyactis) fishery in the Haizhou Bay, China, as a case study. The model was calibrated to realistically capture the fisheries dynamics with hindcasting. Three simulation scenarios featuring different fishing intensities based on status quo and maximum sustainable yield(MSY) were proposed and evaluated with projections. Stochastic projections were additionally performed to investigate the influence of uncertainty associated with recruitment strengths and the implementation of control targets. It was found that fishing at FMSY level could effectively rebuild the depleted stock biomass, while the stock collapsed rapidly in the status quo scenario. Uncertainty in recruitment and implementation could result in variabilities in management effects; but they did not much alter the management effects of the FMSY scenario. These results indicate that the lack of science-based control targets in fishing mortality or catch limits has hindered the achievement of sustainable fisheries in China. Overall, the presented work highlights that the developed projection model can promote the understanding of the possible consequences of fishing under uncertainty and is applicable to other fisheries in China. 相似文献
992.
利用中国东北地区1981—2018年166个地面气象观测站资料,定义了中国东北地区秋冬季霾日指数,分析了年际尺度上该地区霾日数与同期大气环流异常的内在关系。结果表明:中国东北地区秋冬季霾日指数存在显著的年际变化特征,欧亚—太平洋遥相关型(Eurasia-Pacific Teleconnection Pattern, EUP)负位相、东亚大槽偏弱等大气环流异常配置导致中国东北地区秋冬季霾的发生频次增加。巴伦支海与喀拉海北部海域是影响中国东北地区秋冬季霾日年际变化的海冰关键区,该区域海冰面积与霾日数呈显著负相关,北极海冰通过改变大气环流间接影响中国东北地区秋冬季霾日发生频次,当北极海冰异常偏少时,东亚冬季风偏弱,近地面风速偏低,环境湿度偏高,中国东北地区受东北亚异常反气旋西侧的异常偏南风控制,且受“EUP”负位相模态影响,东亚大槽减弱,有利于大气污染物和水汽向中国东北地区输送,该地区秋冬季霾的发生频次增加。 相似文献
993.
Solar energy is clean and renewable energy that plays an important role in mitigating impacts of environmental problems and climate change. Solar radiation received on the earth’s surface determines the efficiency of power generation and the location and layout of photovoltaic arrays. In this paper, the average daily solar radiation of 77 stations in China from 1957 to 2016 was analyzed in terms of spatial and temporal characteristics. The results indicate that Xinjiang, the Qinghai-Tibet Platea... 相似文献
994.
This paper applies the narrow band Internet of things communication technology to develop a wireless network equipment and communication system, which can quickly set up a network with a radius of 100 km on water surface. A disposable micro buoy based on narrow-band Internet of things and Beidou positioning function is also developed and used to collect surface hydrodynamic data online. In addition, a web-based public service platform is designed for the analysis and visualization of the data collected by buoys. Combined with the satellite remote sensing data, the study carries a series of marine experiments and studies such as sediment deposition tracking and garbage floating tracking. 相似文献
995.
热带气旋信息管理系统的初步设计与实现 总被引:1,自引:1,他引:0
为了热带气旋信息提供一个更好更方便的查询、管理平台,设计并建立了热带气旋信息管理系统.系统使用VISUAL BASIC 6.0作为前端应用程序开发工具,并以Access 2000作为后台数据库,利用VB提供的各种面向对象的开发工具,如数据环境,动态的与数据库连接,达到查询、添加、修改、删除数据记录的功能.查询的内容主要包括四个部分:对我国影响简表、中心位置资料表、路径图以及海平面气压图.系统不仅收录了<台风年鉴>资料.并利用1950~2003年的NCEP/NCAR每日四次2.5°×2.5°资料,绘制了热带气旋的海平面气压图;利用世界台风组织的BEST TRACK资料,绘制了热带气旋路径图.系统可以提供比<台风年鉴>更丰富的信息,这也是该系统的鲜明特点. 相似文献
996.
997.
998.
We report the discovery of four new open clusters(named QC 1,QC 2,QC 3 and QC 4)in the direction of Cygnus Cloud and select their members based on five astrometric parameters(l,b,ω,μα*,μδ)of Gaia DR2.We also derive their astrophysical parameters for each new cluster.Structure parameters are generated by fitting the radial density distribution with a King’s profile.Using solar metallicity,we performed isochrone-fitting on their purified color-magnitude diagrams(CMDs)to derive the age of the clusters.The known cluster NGC 7062 in an adjacent area is chosen to verify our identification process.The estimated distance,reddening and age of NGC 7062 are in good agreement with the literature. 相似文献
999.
1000.