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201.
河南省寒潮特征分析与中期预报 总被引:3,自引:0,他引:3
利用1986-1999年气象资料,分析了河南省寒潮天气的基本特征和主要天气形势。利用欧洲中心数值预报产品3层格点实况资料,采用相关分析方法,分别计算出河南省安阳,洛阳,郑州,西华,信阳各代表站的寒潮消空和预报指标。再以欧洲中心72-144h数值预报产品为因子,用完全预报方法做出河南省3-7天中期寒潮天气过程预报。 相似文献
202.
《The Professional geographer》2013,65(1):57-70
This paper analyzes Hungary's export linkages of the interwar and Cold War periods using gravity model and historical analyses. Hungary is a useful example of former Soviet satellites because it combines relative political stability (since 1956) and experimentation with the New Economic Mechanism (NEM) during the 1970s and 1980s. Historical analysis reveals seven events since World War I that changed Hungary's trade patterns. Gravity model analysis for 1955, 1965, 1975, and 1985 shows the dramatic cleavage of the “Iron Curtain,” the effect of the NEM, and particularly strong and weak linkages for Hungarian trade that may result from historical legacies, complementarity, or specific political contacts. 相似文献
203.
Tempo-spatial variation of nutrient and chlorophyll-α concentrations from summer to winter in the Zhangzi Island Area (Northern Yellow Sea) 总被引:1,自引:0,他引:1
Nutrient and Chlorophyll-a (Chl-a) concentrations were investigated monthly along three transects extending from a mariculture area to open waters around the Zhangzi Island area from July to December 2009. The objective of this study is to illustrate food availability to the bottom-sowed scallop Patinopecten yessoensis under the influences of the Yellow Sea Cold Water Mass (YSCWM), freshwater input and feedbacks of cultivated scallops. Significant thermal stratification was present in open waters from July to October, and salinity decreased in July and August in surface layers in the mariculture area. Nutrient concentrations increased with depth in both areas in summer, but were similar through water column in November and December. On average, nutrient increased from summer to autumn in all components except ammonia. Nutrient concentrations lower than the minimum thresholds for phytoplankton growth were present only in upper layers in summer, but stoichiometric nitrogen limitation existed in the entire investigation period. Column-averaged Chl-a concentration was lower in open waters than in mariculture area in all months. It increased significantly in mariculture area in August and October, and was less variable in open waters. Our results show that nutrients limitation to phytoplankton growth is present mainly in upper layer in association with stratification caused by YSCWM in summer. Freshwater input and upwelling of nutrients accumulated in YSCWM can stimulate phytoplankton production in mariculture area. Farming activities may change stoichiometric nutrient ratios but have less influence on Chl-a concentration. 相似文献
204.
This study uses a 30-year time series of standardized bottom trawl survey data (1982–2011) from the eastern Bering Sea shelf to model patterns of summer spatial distribution for various bottom fishes and crabs in response to changes in the areal extent of the cold pool, time lag between surveys, and fluctuations in population abundance. This investigation is the first to include data for the 2006–2010 cold period and to use between-year comparisons of local and shelf-wide spatial indices to test specific responses to three different isothermal boundaries within the cold pool. Distributional shifts in population varied considerably among species and directional vectors for some species were greater in magnitude to the east or west than to the north or south; however, in general, eastern Bering Sea shelf populations shifted southward in response to the increasing cold pool size, and after accounting for differences in temperature and population abundance, there was still a temporal northward shift in populations over the last three decades despite the recent cooling trend. Model results for local and shelf-wide indices showed that survey time lag and cold pool extent had a greater effect on spatial distribution than population abundance, suggesting that density-independent mechanisms play a major role in shaping distribution patterns on the eastern Bering Sea shelf. The area enclosed by the 1 °C isotherm most commonly affects both local and shelf-wide spatial indices suggesting that 1 °C is a more important boundary for describing temperature preferences of eastern Bering Sea bottom fishes and crabs than is the 2 °C isotherm used for designating the physical boundary for the cold pool. 相似文献
205.
一次东北冷涡暴雨的水汽输送特征和位涡分析 总被引:1,自引:0,他引:1
通过对2010年7月27~29日吉林省一次较大范围的冷涡暴雨、大暴雨过程进行诊断分析,建立了此类暴雨的天气概念模型:200 hPa呈现“两脊一槽”型,高空急流呈辐散状位于吉林省上空,急流中心最大风速≥60 m/s;500 hPa东北冷涡强烈发展,鄂海阻高稳定维持是此次强降水发生的重要天气系统,中心最大风速≥20 m/s的偏西风急流带横穿吉林省中部;850 hPa风速≥12 m/s的3条急流带在吉林省中东部地区交汇,形成低层辐合、高层辐散的气旋性涡度柱,较强的垂直上升气柱一直向上伸展到500 hPa附近,极有利于对流的发展和强降水的维持。通过计算整层水汽通量与吉林省逐6 h平均降水量的相关矢量场,结果表明:偏西、偏南及偏北3条水汽通道在吉林省中南部汇集是此次强降水发生的重要条件,暴雨落区与整层水汽通量汇合区密切相关,水汽输送以经向(南北方)水汽流入为主。暴雨期间具有较好的动力、热力及能量条件,特别是湿对流有效位能明显偏强,强降水出现在对流有效位能 (CAPE)值由极大值开始下降的过程中。干侵入是激发冷涡发生、发展的动力条件之一,≥1 PVU(位涡单位)的高位涡舌在下降的过程中,同时南移,与中部地区强降水落区自北向南移动相吻合。 相似文献
206.
207.
《Marine Policy》2017
The air pollutant emissions of the ships at port represent a small percentage of the overall emissions from shipping however they are concentrated in a small area. In Mytilene, Lesvos, the port is located within the city limits, resulting in air pollution, congestion and noise, especially during the tourist season. The aim of this study is to estimate the quantities of particulate matter and CO2 emitted by ships in the port of Mytilene and to explore the potential of shore side electricity to reduce the emissions. The emissions were estimated using the bottom–up methodology, based on the activity of the ships in the port (berthing, maneuvering). Simulation of renewable energy sources was made using Homer Energy microgrid simulation software. The results showed that between the 10th and 20th of August 2012, there were 40 calls of passenger ships, tankers and bulk carriers in the port of Mytilene, emitting 441 kg of PM10 and 282 metric tonnes of CO2. About 63% of PM10 and 77% of CO2 were emitted at the berthing phase and the remaining during the maneuvering. These emissions could be reduced by providing electricity to the ships from a hybrid renewable energy system with wind turbines and photovoltaics, connected to the grid. Simulations showed that the total energy requirements of the ships in the port of Mytilene could be covered by four 1.5 MW wind turbines combined with a 5 MW photovoltaics. With this configuration, renewable energy will exceed the ships' electricity needs for most of the time in order not to increase the power station's load. The excess energy could be fed to the islands' grid, so a costly battery storage system is not necessary to handle the variations of alternative energy. In this way, a considerable reduction of the CO2 and PM10 emissions by the ships in the port occurs, providing a viable solution for a cleaner and healthier environment. 相似文献
208.
本文通过对TC-2卫星上搭载的中性原子成像仪(NUADU)在2004年11月发生的一次大磁暴期间观测到的一系列中性原子(ENA)图像的分析,试图给出环电流在磁暴期间的演化模式.研究表明,南向的行星际磁场(IMF)分量在离子从磁尾向内磁层注入和随后的环电流增长过程中起着关键的作用.IMF转为北向后,离子注入随即很快停止.在离子注入增强期间,离子的漂移路径是开放的,以致大量环电流离子从黄昏侧注入后快速地损失在黄昏至正午的磁层顶.所以,环电流往往在离子漂移路径从开放变为封闭后才达到最大强度,而不是在这之前,尽管那时的离子注入强度更大.在该磁暴主相期间,离子注入发生在17∶00~22∶00 LT范围内,形成极其不对称的环电流分布形态.而在恢复相期间,由于受大的IMF By分量的影响,离子注入区的地方时分布范围东向扩张.对称环电流在磁尾对流减小、离子漂移路径变为封闭形态之后形成.在磁暴恢复相后期,从ENA图像看环电流基本衰减到平静时期的水平,而Dst指数仍然显示较强的磁扰动,这说明越尾电流对Dst指数有很重要的影响. 相似文献
209.
In this paper, data obtained from a 164 m and a195 m meteorological tower in the northern suburb ofNanjing have been used to estimate and analyzetime-space distributions for velocity spectra andscales of multi-scaling turbulence during thepassages of two cold fronts. Results show that anon-precipitating weak cold front and aprecipitating cold front were clearly revealed bytheir wind field structures. The frontal passageinfluenced all meteorological variables over aperiod of 18–24 hours for the former, and a longerperiod of 44–56 hours for the latter. During these periods there occurred gust surges and eddymotions of various meso- and micro-scales with periodsof 3–4 hours and 1–20 minutes respectively. In the inertialsubrange Kolmogorov's -2/3 power law for thevelocity spectrum is partly distorted and theturbulence in the atmospheric boundary layer is not isotropic. 相似文献
210.