近22 a人为气溶胶对东亚地区夏季风环流影响的数值模拟研究   总被引：1，自引：1，他引：0       下载免费PDF全文

陈明诚  孙照渤  沈新勇  王勇  吉振明 《大气科学学报》2014,37(4):395-404

运用区域气候模式RegCM3耦合入一个化学过程,对东亚地区三类人为排放气溶胶（硫酸盐、黑碳和有机碳）的时空分布特征及其对夏季风环流的影响进行了数值模拟研究。模拟结果显示,气溶胶的引入会引起东亚地区夏季850 hPa风场发生改变,我国江淮以东洋面上空出现了一个气旋式距平环流中心,中心以西的偏北风气流将削弱东亚地区夏季西南季风。通过讨论春季中国地区气溶胶浓度与夏季东亚地区850 hPa经向风的时滞关系,以及夏季中国地区气溶胶浓度与同期东亚地区850 hPa经向风的关系,可以发现,春、夏季中国地区气溶胶浓度均与夏季东亚地区850 hPa经向风有很好的负相关关系,当春季中国北方和夏季中国南方地区气溶胶浓度增加时,中国东部地区夏季偏南季风减弱。这可能与气溶胶改变了大气层顶和地表的辐射强迫,进而引起了海陆气压差异和位势高度场的变化有关。  相似文献   

2008年1月欧亚阻塞形势的ECMWF集合预报效果评估检验          下载免费PDF全文

王毅  金荣花  代刊  牛若芸  曹勇 《大气科学学报》2014,37(3):257-267

基于欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)集合预报系统资料,评估和讨论了2008年1月我国南方发生严重冰冻雨雪灾害期间欧亚中高纬阻塞形势的预报效果。结果表明,2008年1月阻塞形势发生频率极端偏高,ECMWF集合预报的阻塞发生频率随着预报时效的延长逐渐降低。环流预报效果检验表明,预报时效大于6 d时,集合平均的预报效果好于确定性预报,因此集合预报的优势主要体现在中期预报时段。对阻塞形势的可预报性的分析表明,阻塞崩溃期间的可预报性低于阻塞建立期间。另外,通过集合预报可以获得阻塞发生的概率,从而提前为预报员提供可能发生阻塞的信号。  相似文献   

地热对海洋影响的实验室模拟     

ZHOU Shengqi  QU Ling  ZHAO Xiaozheng  WAN Wei 《海洋学报(英文版)》2014,33(9):25-31

This study, using laboratory experiments and scaling analysis, evaluates the influence of geothermal heating on global oceanic circulation. Upon a well-developed large-scale convective flow, an additional heat flux perturbation δF/F is employed. The increments of flow and thermal properties, including eddy diffusivity KT, flow velocity V and bottom temperature Tb, are found to be independent of the applied heat flux F. Together with the scaling analysis of convective flow at different configurations, where the flow is thermally driven in the relatively low or extremely high turbulent thermal convections or the horizontal convection, the variances of flow properties, δKT/KT and δV/V, are found to be close to 0.5% and 0.75% at δF/F=2%. This means that the small heat flux perturbation plays a negligible role in the global convective flow. However, δTb/ΔT is found to be 1.5% at δF/F=2%, which would have a significant effect in the local region. The results might provide a clue to understanding the influence of geothermal heating on global oceanic circulation. It is expected that geothermal heating will contribute less than 1% in turbulent mixing and volume flux to global oceanic circulation, so its influence can be negligible in this situation. However, when it comes to the local environment, the influence of geothermal heating cannot be ignored. For example, temperature increases of about 0.5°C with geothermal heating would have a significant effect on the physical environments within the benthic boundary layer.  相似文献   

北部湾的环流和水团对季节性强迫的响应   总被引：1，自引：1，他引：0  

GAO Jingsong  SHI Maochong  CHEN Bo  GUO Peifang  ZHAO Dongliang 《海洋学报(英文版)》2014,33(7):1-11

In the past 20 a, the gulf-scale circulation in the Beibu Gulf has been commonly accepted to be driven by a wind stress or density gradient. However, using three sensitive experiments based on a three-dimensional baroclinic model that was verified by observations, the formation mechanisms were revealed： the circula- tion in the northern Beibu Gulf was triggered by the monsoon wind throughout a year; whereas the southern gulf circulation was driven by the monsoon wind and South China Sea （SCS） circulation in winter and sum- mer, respectively. The force of heat flux and tidal harmonics had a strong effect on the circulation strength and range, as well as the local circulation structures, but these factors did not influence the major circulation structure in the Beibu Gulf. On the other hand, the Beibu Gulf Cold Water Mass （BGCWM） would disappear without the force of heat flux because the seasonal thermocline layer was generated by the input of heat so that the vertical mixing between the upper hot water and lower cold water was blocked. In addition, the wind-induced cyclonic gyre in the northern gulf was favorable to the existence of the BGCWM. However, the coverage area of the BGCWM was increased slightly without the force of the tidal harmonics. When the model was driven by the monthly averaged surface forcing, the circulation structure was changed to some extent, and the coverage area of the BGCWM almost extended outwards 100%, implying the circulation and water mass in the Beibu Gulf had strong responses to the temporal resolution of the surface forces.  相似文献   

越南离岸流跨海盆特征初步分析   总被引：3，自引：0，他引：3  

刘岩松  于非  刁新源  南峰 《海洋科学》2014,38(7):95-102

为了更加清晰地分析南海的环流结构,本文利用南海表层卫星跟踪漂流浮标轨迹,结合卫星高度计资料,分析了南海中、南部跨海盆尺度海流。结果表明,2011年9~10月,越南沿岸流向南,并分别在11.5°N和8.5°N(等深线出现弯曲处)转向东形成越南离岸流。之后,这支离岸流在11°~16°N呈现蛇形路径,从越南东岸跨越南海南部海盆到达菲律宾西岸。分析卫星高度计数据,结果表明,秋季南海中北部被气旋式环流控制,气旋式环流南部为东向流,可从越南东部一直到菲律宾沿岸,从而决定了越南离岸流跨海盆的特征。越南离岸流的蛇形路径主要是由反气旋-气旋-反气旋-气旋交错出现的中尺度涡决定的。  相似文献   

Development of the Western Boundary Undercurrent at Eirik Drift related to changing climate since the early Miocene     

《Deep Sea Research Part I: Oceanographic Research Papers》2014

Eirik Drift lies on the slope south of Greenland, where it has been formed under the influence of the Western Boundary Undercurrent (WBUC) closely downstream of its origin in the deep-water formation centres of the Nordic Seas. Therefore, the sediment record at Eirik Drift documents modifications in pathways and intensity of the WBUC. These modifications reflect alterations in deep-water formation in the Nordic Seas and are therefore coupled with climate changes. Based on the seismostratigraphic analysis of sedimentary architecture identified in a set of high-resolution seismic reflection data, we have reconstructed the palaeocirculation of the WBUC at Eirik Drift since the early Miocene. We revealed a strong WBUC during warm climate conditions, and in phases of climate cooling with enhanced sea-ice extent we interpreted weak WBUC influence. We suggest a southward shift of the deep-water formation regions along with a shift of the deep current system during the cool phases. This shift implies that the main North Atlantic Deep Water route affected Eirik Drift only during warm phases and that during cool phases weak branches of the circulation system flowed over Eirik Drift.  相似文献   

山东主雨季突变特征及成因     

于群  周发琇  王启 《中国海洋大学学报(自然科学版)》2014,44(8):18-24

采用山东省111个地面测站45年(1965—2009年)逐日降水量资料,分析了山东主雨季的气候特征,特别是降水量的突变性。经统计检验确认,5~10月候(日)降水量(以下简称降水)序列存在3次突增或骤减的显著突变,主雨季定义在第1次突变至第3次突变之间,即36~49侯,历时14侯。第2次突变发生在8月中旬,是主雨季内一个短时降水减少过程,与副高的短暂南撤有关。突变是在降水的年循环和季节变化背景下,由月内振荡对季节内振荡的调制中发生的。主雨季的进程与副高和西风带系统相对位置的变动紧密相关,3次突变的环流特征各不相同,每一次突变都显示出特定的环流结构,山东主雨季起讫的降水突变是由不同尺度大气环流相互调整的结果。  相似文献   

Mean Flow–Storm Track Relationship and Rossby Wave Breaking in Two Types of El-Nino简   总被引：1，自引：0，他引：1  

LIU Chengji  REN Xuejuan  YANG Xiuqun 《大气科学进展》2014,31(1):197-210

The features of large-scale circulation, storm tracks and the dynamical relationship between them were examined by investigating Rossby wave breaking （RWB） processes associated with Eastern Pacific （EP） and Central Pacific （CP） E1-Nifio. During EP E1-Nino, the geopotential height anomaly at 500 hPa （Z500） exhibits a Pacific-North America （PNA） pattern. During CP EI-Nifio, the Z500 anomaly shows a north positive-south negative pattern over the North Pacific. The anomalous distributions of baroclinicity and storm track are consistent with those of upper-level zonal wind for both EP and CP EI-Nino, suggesting impacts of mean flow on storm track variability. Anticyclonic wave breaking （AWB） oczurs less frequently in EP EI-Nino years, while cyclonic wave breaking （CWB） occurs more frequently in CP EI-Nino years over the North Pacific sector. Outside the North Pacific, more CWB events occur over North America during EP Ei-NiNo. When AWB events occur less frequently over the North Pacific during EP EI-Nino, Z500 decreases locally and the zonal wind is strengthened （weakened） to the south （north）. This is because AWB events reflect a monopoie high anomaly at the centroid of breaking events. When CWB events occur more frequently over the North Pacific under CP EI-Nino conditions, and over North America under EP EI-Nino condition, Z500 increases （decreases） to the northeast （southwest）, since CWB events are related to a northeast-southwest dipole Z500 anomaly. The anomalous RWB events act to invigorate and reinforce the circulation anomalies over the North Pacific-North America region linked with the two types of EI-Nino.  相似文献   

A Model Simulation of Future Oceanic Conditions along the British Columbia Continental Shelf. Part II: Results and Analyses     

M.G.G. Foreman  W. Callendar  D. Masson  J. Morrison  I. Fine 《大气与海洋》2014,52(1):20-38

An ocean circulation model for the British Columbia continental shelf is run with future initial conditions and forcing fields downscaled from the North American Regional Climate Change Assessment Program archive. Average seasonal sea surface temperatures for the period 2065 to 2078 are projected to increase by between 0.5° and 2.0°C with respect to analogous averages from 1995 to 2008. Seasonal sea surface salinities are projected to decrease by as much as 2.0 over the same period, though there are some regions where and periods when small increases are projected. Though stronger winter winds result in larger Haida Eddies, slightly stronger summer winds along the western Vancouver Island shelf do not result in appreciable changes to either the cross-shelf upwelling or to the magnitude of Juan de Fuca Eddies or the timing of their formation. However, increased flows are projected in some seasons for the Rose Spit, Middle Bank, and Goose Island Bank eddies. More precipitation over the watersheds emptying into coastal waters produces larger freshwater discharges and, in particular, a stronger estuarine flow in Juan de Fuca Strait and a stronger Vancouver Island Coastal Current. Generally increasing winds and decreasing density mean that the winter minus summer range of sea surface heights is projected to increase all along the coast.  相似文献   

Distribution of deep carbon dioxide in relation to the structure and tectonic evolution of south-east France     

François Arthaud  Jean Dazy  Jean-Claude Grillot 《Geodinamica Acta》2013,26(2):86-102

Abstract

Throughout SE France, ¹³C-values of CO₂releases suggest that a variable part of the C0₂ emission derives from mantle and/or lower crust. Carbon dioxide emission takes place in various geological settings. Geodynamical analyses lead to the identification of five provinces: the Sub-Alpine Ranges, the French Massif Central, the Mediterranean part of the Languedoc, the western Pyrénées and the Alps at the West of the Penninic front. Possible correlations are suggested between CO₂ flux and tectonic history of the structural provinces.

Possible processes by which CO₂ is extracted from the mantle, stored and transferred to the surface are investigated for each of these provinces. Major crustal scale gas movements may have taken place during the Carboniferous (Variscan and Late Variscan tectogenesis), the Lias and Dogger (rifting), the Upper Cretaceous and the Cenozoic (Alpine tectogenesis), A model of successive circulations of fluids on the scale of the whole Southeastern France CO₂-belt is proposed. This integrated isotopic and geodynamic approach contributes to a better understanding of the regional CO₂flux.  相似文献