强雷暴环境的客观预报：决策树与区域业务数值天气预报模式     

Mills  GA 廖晓农 《气象科技》1999,(4):14-24

澳大利亚区域业务数值天气预报模式的输出产品已被用作为热力学和动力学场输入到决策树中,该决策树用于诊断雷暴产生的可能性以及产生雷暴的环境是否会进一步导致强雷暴、超级单体或龙卷超级单体雷暴的发生。在所描述的强天气观测的目标个例中,系统成功地识别了强雷暴而且大致区分出龙卷和非龙卷事件。研究结果表明:当与区域数值天气预报模式相结合时,Colquhoun 的雷暴决策树有能力为雷暴区、强雷暴、龙卷雷暴区的预报以及判断这些雷暴是否可能伴有暴洪、下击暴流、强风等提供指导。强天气目标个例研究的结果表明:就所观测的强天气的位置及类型而言,上述方法的准确度很高。如果这些结果能够重现于业务实践中,该系统将对预报人员十分有益。33 天的试验结果表明:虽然根据公认的相当宽松的主观判据确定的错误报警数量相对较低以及预报准确的数目相对较高,但过多的空间超报使得个例研究的结果并未出现。这些结果表明:决策树系统可以提供一个有用的警报系统,该系统构成澳大利亚业务工作中确定雷暴监视区的基础。  相似文献   

Changes in the functions of Soviet cities with growth     

Gornostayeva GA 《Soviet geography》1984,25(7):481-488

"A sample of Soviet cities (the largest 100 cities in the RSFSR) is used to develop a model relating city size, city function and the city's force of attraction (in-migration rates)....[It is found that] city growth...is accompanied by a change in functional structure and an increase in the importance of some functions at the expense of others....A change in functional structure, in turn, produces a change in the city's force of attraction, resulting in either an increase or a decline of in-migration."  相似文献   

The impact of legislation on the usage and environmental concentrations of Irgarol 1051 in UK coastal waters     

Cresswell T  Richards JP  Glegg GA  Readman JW 《Marine pollution bulletin》2006,52(10):1169-1175

In 2001, legislative measures were introduced in the UK to restrict usage of antifouling agents in small (<25 m) vessel paints to dichlofluanid, zinc pyrithione and zineb. This removed the previously popular booster biocides diuron and Irgarol 1051 from the market. To investigate the impact of this legislation, water samples were taken from locations where previous biocide levels were well documented. Results from analyses demonstrate a clear reduction in water concentrations of Irgarol 1051 (between 10% and 55% of that found during pre-restriction studies), indicating that legislation appears to have been effective. Although other booster biocides were screened for (chlorothalonil, dichlofluanid and Sea-Nine 211), they were below the limits of detection (<1 ng/l) in all samples. A survey of chandlers and discussions with legislative authorities supports these results and concurs the removal of Irgarol 1051 based paints from the market using simple regulations at a manufacturer level with little regulation at a retailer level.  相似文献   

Food web analysis in two permanently open temperate estuaries: consequences of saltmarsh loss?     

Svensson CJ  Hyndes GA  Lavery PS 《Marine environmental research》2007,64(3):286-304

Saltmarsh vegetation, seston and microphytobenthos are all conspicuous components of most temperate estuaries and they potentially contribute to the estuarine food chain. Yet their relative contributions are unclear, as is the significance of saltmarsh losses through natural and human-induced impacts. This study aimed to quantitatively determine the contribution of various types of primary producers to detritus in the Walpole-Nornalup Estuary and Leschenault Inlet, two permanently open estuaries in SW Australia, and, estimate the flow of different types of detritus to higher trophic levels, using carbon ((13)C) and nitrogen ((15)N) stable isotopes as tracers. Results of the mixing model indicated that seston, microphytobenthos and to some extent seagrass and fringing saltmarsh were the main contributors to the detrital pool in both estuaries. However, the relative contribution of different primary producers varied both within and between estuaries. The contribution of saltmarsh was higher at sites close to rivers and dense fringing vegetation, while seston, microphytobenthos and seagrass dominated the detrital material at other sites. Benthic harpacticoid copepods were shown to feed on detritus though they appeared to actively select for different components of the detritus depending on site and estuary. Isotopic signatures of other consumers indicated that fish and invertebrates derived nutrients from MPB and detritus, either directly as food or indirectly through feeding on invertebrates. The overall contribution of saltmarsh to detritus was lower in Leschenault Inlet than in Walpole-Nornalup Estuary, possibly as a result of increased clearing of fringing vegetation around Leschenault Inlet. This pattern was however not reflected in harpacticoid food. Therefore, although losses of fringing saltmarsh around estuaries have the potential to significantly affect estuarine food webs, the significance of such losses will be site- and estuary-dependent.  相似文献   

The effect of nitric oxide on the growth of marine phytoplankton   总被引：13，自引：0，他引：13  

ZHANG Zhengbin  LIN Cai  LIU Chunying  SUN Mingyi  DING HaibingThe Institute of Marine Chemistry  Ocean University of China  Qingdao  P.R.ChinaThe University of Georgia  Department of Marine Sciences  Athen GA   《中国海洋大学学报(英文版)》2003,2(2):185-188

The incubation experiments of Skeletonema costatum, Dicrateria zhanjiangensis nov. sp., and Platymonas sub-cordiformis, and those of Emiliania huxleyi were carried out in the Marine Physical Chemistry Laboratory in Ocean University of China and in the Marine Organic Geochemistry Laboratory in the University of Georgia respectively. Nitric oxide was added into the media when these marine microalgae were growing. We found the growth of these four microalgae were promoted or inhibited when nitric oxide of different concentrations was added one or two times each day during the cultivation process. The results are consistent with the influence of nitric oxide on the growth of high plants. The results show that nitric oxide may be a new factor of regulation and control for the phytoplankton growth in seawater.  相似文献   

Human-Environment Patterns of Metropolitan Spatial Restructuring:Atlanta,Georgia and Shanghai,PRC,1950-2000     

Susan M. Walcott 《世界地理研究》2002,11(2):27-33

1　ＩｎｔｒｏｄｕｃｔｉｏｎＭｏｄｅｌｓｏｆｍｅｔｒｏｐｏｌｉｔａｎｓｐａｔｉａｌｅｖｏｌｕｔｉｏｎｌａｒｇｅｌｙｄｅｒｉｖｅｆｒｏｍｅｘｐｅｒｉｅｎｃｅｓｕｎｄｅｒａｍａｒｋｅｔｅｃｏｎｏｍｙ .Ｄｅｖｅｌｏｐｉｎｇｗｏｒｌｄ ｐａｔｔｅｒｎｓｉｎｍｏｒｅ ｇｏｖｅｒｎｍｅｎｔ＿ｄｉｒｅｃｔｅｄｓｙｓｔｅｍｓｒｅｍａｉｎｕｎｄｅｒ＿ｅｘａｍｉｎｅｄ.Ｔｈｉｓ ｐａｐｅｒｃｏｍｐａｒｅｓｔｈｅｕｒｂａｎｓｐａｔｉａｌｐａｔｔｅｒｎｓａｎｄｅｎｖｉｒｏｎｍｅｎｔａｌｅｆｆｅｃｔｓｏｆｅｘｐｌｏｓｉｖｅｍ…  相似文献   

Weathering of an Arctic oil spill over 20 years: the BIOS experiment revisited. Baffin Island Oil Spill     

Prince RC  Owens EH  Sergy GA 《Marine pollution bulletin》2002,44(11):1236-1242

A small experimental oil spill was conducted on the northern tip of Baffin Island Nunavut, Canada (72 degrees 31' N, 79 degrees 50' W) in August 1981, and the natural weathering of the oil has been followed by periodic visits. This paper reports on the chemical composition of oil collected in August 2001. The vast majority of the initial oil has gone, but small patches remain. Some samples remain essentially unaltered despite their 20 years of exposure to the elements, while others show that biodegradation and photooxidation can play important roles in removing the majority of the components of the oil. Using 17alpha(H)21beta(H)hopane as a conserved marker within the oil, we show that the most biodegraded sample has lost more than 87% of the hydrocarbons initially present, while another has lost a substantial proportion of its initial chrysene and alkylated congeners. Potential explanations for the different weathering patterns seen in samples collected from this small site are briefly discussed.  相似文献   

油气生产中的人体健康风险评价     

Uiri.  GA 句少华 《世界地质》1994,13(4):142-150

这篇报告叙述了油气生产基地的地面蓄水池对人身基本健康风险的调查和争议。风险评价表明，在将来的使用条件下，被污染的土壤不需铲除，也可以保护人类身体健康。依据这一结果，管理部门允许不铲除污染的土壤，从而节省先前准备改造工程的费用。研究结果表明：（１）好的基本健康风险评价能够挽救大量资源而不增加企业的责任；（２）在石油勘探和生产中采用基本健康风险评价确定改造和清除污染目标；（３）当健康风险评价计划受环境科学支持的时候，根据风险变化趋势批准不采取挖掘土壤的方法清除所有化学污染而终止了对基本计划的争议。  相似文献   

荒漠动植群落类型与演化过程概览     

波利.  GA 李胜功 《世界沙漠研究》1994,(1):21-23

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巴布亚新几内亚的波格拉金矿床     

Hand.  GA 林晓辉 《国外前寒武纪地质》1989,(1):53-60

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