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251.
This study reveals that the interannual variability of the western edge of the western North Pacific(WNP)subtropical high(WNPSH) in early summer experienced an interdecadal decrease around 1990. Correspondingly, the zonal movement of the WNPSH and the zonal extension of the high-pressure anomaly over the WNP(WNPHA) in abnormal years possess smaller ranges after 1990. The different influences of the tropical SSTAs are important for this interdecadal change, which exhibit slow El Nino decaying pat...  相似文献   
252.
"La Madre" is a kind of upper atmospheric air current, and occurs as "warm phase" and "cold phase" in the sky of Pacific Ocean alternately. There exists this phenomenon, called "Oscillation Decade in the Pacific" (ODP), for 20 - 30 years. It is concerned with 60 year cycle of the tides. Lunar oscillations explain an intriguing 60-year cycle in the world's temperature. Strong tides increase the vertical mixing of water in the oceans, drawing cold ocean water from the depths to surface, where it cools the atmosphere above. The first strong seismic episode in China was from 1897 to 1912; the second to the fifth was the in 1920-1937, 1946-1957, 1966-1980, 1991-2002, tsrectruely. The alternative boundaries of"La Madre" warm phase and cold phase were in 1890, 1924, 1946 and 2000, which were near the boundaries of four strong earthquakes. It indicated the strong earthquakes closedly related with the substances' motion of atmosphere, hydrosphere and lithosphere, the change of gravity potential, and the exchange of angular momentum. The strong earthquakes in the ocean bottom can bring the cool waters at the deep ocean up to the ocean surface and make the global climate cold. the earthquake, strong tide and global low temperature are close inrelntion for each othen.  相似文献   
253.
Synthesis analysis and singular value decomposition (SVD) methods were used to study the impact of surface air temperature (SAT) over Asian-Pacific region on the summertime northeastern Asian blocking high (NABH) with NCEP/NCAR Reanalysis Data.The results showed that 500 hPa geopotential height and SAT fields over Asian-Pacific region shared the similar pattern of East Asian Pacific (EAP) wave train;there was steady remote response relationship between the EAP wave train in summer and the "+-+" pattern of tropical SAT in zonal direction from former winter to summer;there were two relative negative(positive) Walker circulations over the tropical Indian Ocean and Pacific when being more(less) summertime NABH. The influence of sea surface temperature anomaly (SSTA) on the summertime NABH was possibly as follows.The special distribution of SSTA in tropical zonal direction continuously forced the tropical convection and zonal circulation from former winter to summer,and led them to act anomaly.Finally the abnormal conditions were transported to middle-high latitudes through EAP wave train and yielded the advantageous or disadvantageous atmospheric circulation background for the summertime NABH.  相似文献   
254.
Based on the precipitation data of Meiyu at 37 stations in the valleys of Yangtze and Huaihe Rivers from 1954 to 2001, the temporal-spatial characteristics of Meiyu precipitation and their relationships with the sea surface temperature in northern Pacific are investigated using such methods as harmonic analysis, empirical orthogonal function (EOF), composite analysis and singular value decomposition (SVD). The results show that the temporal evolution and spatial distribution of Meiyu precipitation are not homogeneous in the Yangtze-Huaihe Rivers basins but with prominent inter-annual and inter-decadal variabilities. The key region between the anomalies of Meiyu precipitation and the monthly sea surface temperature anomalies (SSTA) lies in the west wind drift of North Pacific, which influences the precipitation anomaly of Meiyu precipitation over a key period of time from January to March in the same year. When the SST in the North Pacific west wind drift is warmer (colder) than average during these months, Meiyu precipitation anomalously increases (decreases) in the concurrent year. Results of SVD are consistent with those of composite analysis which pass the significance test of Monte-Carlo at 0.05.  相似文献   
255.
东太平洋海隆深海热液区沉积物古菌多样性分析   总被引:1,自引:0,他引:1  
采用PCR-RFLP方法对东太平洋海隆深海热液区3个站位沉积物中的古菌多样性进行了初步研究.结果显示,从古菌16S rRNA基因文库中随机挑取的296个阳性克隆分属奇古菌门(Thaumarchaeota,47.64%)、广古菌门(Euryarchaeota,44.93%)、泉古菌门(Crenarchaeota,6.77%)和未分类古菌(0.68%),其中优势菌群为奇古菌门的亚硝化侏儒菌属(Nitrosopumilus,35.47%)和广古菌门的热原体纲(Thermoplasmata,27.03%),DHVE3、DHVE5、DHVE6、MBGB和MBGE类群在沉积物样品中也均有发现.另外,3个站位沉积物中古菌类群组成存在差异,S5-TVG1站位样品文库的97个古菌克隆分属奇古菌门(49.48%)、广古菌门(49.48%)和泉古菌门(1.03%),S14-TVG10站位样品文库的103个古菌克隆由奇古菌门(84.47%)和广古菌门(15.53%)组成,S16-TVG12站位样品文库的96个古菌克隆包括广古菌门(71.88%)、泉古菌门(19.79%)、奇古菌门(6.25%)和未分类古菌(2.08%).研究结果表明,东太平洋海隆深海热液区沉积物中古菌多样性丰富,存在着许多新的古菌菌群;不同站位古菌菌群结构以及多样性存在差异,这与其所处环境的热液活动密切相关.  相似文献   
256.
中国北方地区石炭纪岩相古地理   总被引:8,自引:2,他引:8  
中国北方地区包括西北地区、华北地区和东北地区。该地区石炭系划分为上、下统,在西北地区、东北地区石炭系发育完整,华北地区普遍缺失下石炭统。87个标准剖面和529个辅助剖面的岩相古地理研究表明:早石炭世中国北方地区主要存在佳木斯古陆、额尔古纳古陆、中朝古陆、东塔里木─敦煌─中祁连─阿拉善古陆、陇西古陆、准噶尔─吐哈古陆、阿勒泰古陆等;从东至西主要发育松辽海盆、辽东海湾、北山海盆、祁连海、柴达木台地、宗务隆山海槽、塔里木台地、西昆仑海盆、南天山海盆、北天山─准噶尔海盆等海相沉积。晚石炭世海侵范围扩大,佳木斯古陆、额尔古纳古陆仍然存在,中朝古陆已明显缩小至其北部地区,东塔里木-敦煌-阿拉善古陆范围缩小,陇西古陆向西延伸扩大,北准噶尔─阿勒泰连为一体形成古陆;发育松辽海盆、华北海、祁连海、柴达木台地、宗务隆山海槽、塔里木海盆、南准噶尔-博格达山海盆等海相沉积。  相似文献   
257.
Increasing numbers of approaches to assess eutrophication, such as estuarine trophic status, the Oslo-Paris Commission Common Procedure, and the Water Framework Directive, focus on the symptoms of eutrophication. In China, however, nutrient index methods dominate the assessment of coastal waters. In this study, an integrated method that includes both water quality and ecological response was compared with the Northwest Pacifi c Action Plan (NOWPAP) Common Procedure. Observation data from Jiaozhou Bay, Shandong, China, were used in a comparison of the two methods in a trophic status study. Overall, both clearly revealed a high level of nutrient enrichment in the bay, indicated by high nutrient concentrations. Though the two methods diff ered in their methodological design in the assessment of the ecological eff ects of nutrient enrichment, they have acquired similar results: the integrated method suggested that the status was good, and the NOWPAP Common Procedure suggested that the status was low (indicating that the bay had no serious eutrophication problem). The introduction of fi lter feeders (shellfi sh aquaculture) into the bay on a reasonable scale may have been eff ective in mitigating eutrophic conditions, and perhaps explains the low ecological impacts there. Our results will be useful to ecosystem-based eutrophication management in the bay and in similar areas.  相似文献   
258.
研究海洋的波候变化是了解海洋动力过程对气候变迁响应的关键。渤海所处特殊的地理位置,使其波候在长期风场变化影响下存在阶段性变化特征。文章采用1950~2011年NCEP再分析资料中的渤海海域10 m风场资料,利用SWAN模式模拟逐月渤海波浪的有效波高、波向、波周期,分析该海区波候的变化特征。分析结果显示:1950~2011年期间渤海海域的有效波高呈现下降的趋势;波向角度均呈现上升的趋势,波周期相对平稳,略有上升;有效波高平均下降0.3 cm/a,波向角度平均增加0.12°/a。有效波高在1968年前后显现突变点,波向角度约在1960年突变,波周期在1965年左右出现突变点。渤海波候变化与海气振荡密切相关,是大尺度的大气环流变异导致的结果,长期气候变化背景下,东亚环流天气系统的长期变化(包括东亚季风强度、夏季风北界的移动,西太平洋副热带高压面积与强度的变化、脊点位置西伸与北进,以及西风指数的强弱变化等),是影响和控制渤海海域波气长期变化的主要原因。  相似文献   
259.
东亚夏季风雨带和西太平洋副高季节变化的耦合特征   总被引:9,自引:6,他引:9  
利用NCEP/NCAR数据集中1950~1999年4~9月500hPa位势高度和逐日降水率(PRATE)资料,通过奇异值分解,主要探讨了东亚夏季风雨带与西太平洋副高季节移动的耦合关系。分析发现,模态方差的大小只反映模态对整个分析时段和整个分析区域贡献的大小,但对某些时段、某些区域来说,方差较小模态的贡献很大;因而仅以模态方差贡献的大小来判定模态的重要性是不完全的,只有多个模态的配合才能比较全面地揭示两个场的耦合特征。结果表明:东亚夏季风雨带在不同地区的跳跃对应着西太平洋副高的三次突变,不同模态对三次突变有不同的贡献。  相似文献   
260.
利用NCEP/NCAR1998年5-8月逐日500hPa高度场再分析资料及中国国家气象中心整编的同时段全国160站降水资料,就1998年夏季500hPa行星尺度环流系统对长江流域“二度梅”的影响进行了深入研究。结果发现,鄂霍次克海附近阻塞高压加强(减弱)和副热带西太平洋高压西部强度减弱(加强)的反位相变化是造成长江中下游和东北大部分地区的降水增加(减少)的重要原因。  相似文献   
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