Wind and tidal forcing on the meso-scale circulation in Storfjorden,Svalbard     

R. Skogseth  A.D. Sandvik  L. Asplin 《Continental Shelf Research》2007

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洞庭湖区域雷暴大风分型及预报分析研究     

蔡荣辉  姚蓉  黄小玉  唐明晖  王青霞  彭洁 《气象》2017,43(5):560-572

文章选取2013-2015年洞庭湖区域的15次雷暴大风天气过程,根据天气形势配置将其分为以下4类:低层暖平流强迫类、斜压锋生类、准正压类及高层冷平流强迫类。其中低层暖平流强迫类根据中低层切变线北侧冷平流的强弱又可以分为:强冷暖平流强迫类、强暖平流强迫类和中间类。总结归纳各类雷暴大风过程开始前、影响阶段及过程结束的天气形势配置、雷达回波特征与预报着眼点,为短期、短时天气预报预警提供参考。  相似文献   

玉溪2011年3月强倒春寒天气环流特征分析   总被引：4，自引：1，他引：3  

解福燕  杨海光  杨红 《云南地理环境研究》2012,24(2):73-77

2011年3月15日～18日,云南省玉溪市出现一次强倒春寒天气过程,平均气温除元江外,其余县仅有6．2～8．8℃;48小时最高气温下降17～23℃,通海16日最低气温只有1．8℃。分析1971～2010年历史上3月倒春寒发生前的1月大气物理特征量发现,此次倒春寒的原因主要是由于1月极涡面积偏大,3月强度迅速发展偏强,对应极圈西南侧为120～80gpm的负距平,有利于冷空气形成;经向环流南北交换大,南支槽和东亚槽比常年偏强,有利于暖湿气流的输送,青藏高压比常年偏弱,有利于冷空气南下,造成自北向南出现较大的降温幅度,其中云南东部等地降温幅度超过12℃。  相似文献   

Summer Asian-Pacific Oscillation and Its Relationship with Atmospheric Circulation and Monsoon Rainfall   总被引：1，自引：0，他引：1       下载免费PDF全文

ZHAO Ping  CHEN Junming  XIAO Dong  NAN Sulan  ZOU Yan  ZHOU Botao 《Acta Meteorologica Sinica》2008,22(4):455-471

Using the ERA-40 data and numerical simulations, this study investigated the teleconnection over the extratropical Asian-Pacific region and its relationship with the Asian monsoon rainfall and the climatological characteristics of tropical cyclones over the western North Pacific, and analyzed impacts of the Tibetan Plateau （TP） heating and Pacific sea surface temperature （SST） on the teleconnection. The Asian-Pacific oscillation （APO） is defined as a zonal seesaw of the tropospheric temperature in the midlatitudes of the Asian-Pacific region. When the troposphere is cooling in the midlatitudes of the Asian continent, it is warming in the midlatitudes of the central and eastern North Pacific; and vice versa. The APO also appears in the stratosphere, but with a reversed phase. Used as an index of the thermal contrast between Asia and the North Pacific, it provides a new way to explore interactions between the Asian and Pacific atmospheric circulations. The APO index exhibits the interannual and interdecadal variability. It shows a downward trend during 1958-2001, indicating a weakening of the thermal contrast, and shows a 5.5-yr oscillation period. The formation of the APO is associated with the zonal vertical circulation caused by a difference in the solar radiative heating between the Asian continent and the North Pacific. The numerical simulations further reveal that the summer TP heating enhances the local tropospheric temperature and upward motion, and then strengthens downward motion and decreases the tropospheric temperature over the central and eastern North Pacific. This leads to the formation of the APO. The Pacific decadal oscillation and El Nino/La Nina over the tropical eastern Pacific do not exert strong influences on the APO. When there is an anomaly in the summer APO, the South Asian high, the westerly jet over Eurasia, the tropical easterly jet over South Asia, and the subtropical high over the North Pacific change significantly, with anomalous Asian monsoon rainfall and tropical cyclon  相似文献   

MM5 Simulations of the China Regional Climate During the LGM.Ⅱ: Influence of Change of Land Area, Vegetation, and Large-scale Circulation Background          下载免费PDF全文

LIU Yu  HE Jinhai  LI Weiliang  CHEN Longxun 《Acta Meteorologica Sinica》2008,22(1)

Using a regional climate model MM5 nested to an atmospheric global climate model CCM3, a series of simulations and sensitivity experiments have been performed to investigate the relative LGM climate response to changes of land-sea distribution, vegetation, and large-scale circulation background over China.Model results show that compared with the present climate, the fluctuations of sea-land distribution in eastern Asia during the LGM result in the temperature decrease in winter and increase in summer. It has significant impact on the temperature and precipitation in the east coastal region of China. The impact on precipitation in the east coastal region of China is the most significant one, with 25%-50% decrease in the total precipitation change during the LGM. On the other hand, the changes in sea-land distribution have less influence on the climate of inland and western part of China. During the LGM, significant changes in vegetation result in temperature alternating with winter increase and summer decrease, but differences in the annual mean temperature are minor. During the LGM, the global climate, i.e., the large-scale circulation background has changed significantly. These changes have significant influences on temperature and precipitation over China. They result in considerable temperature decreases in this area, and direct the primary patterns and characteristics of temperature changes. Results display that, northeastern China has the greatest temperature decrease, and the temperature decrease in the Tibetan Plateau is larger than in the eastern part of China located at the same latitude. Moreover, the change of large-scale circulation background also controls the pattern of precipitation change. Results also show that, most of the changes in precipitation over western and northeastern parts of China are the consequences of changing large-scale circulation background, of which 50%-75% of precipitation changes over northern and eastern China are the results of changes in large-scale circulation background. Over China, the LGM climate responses to different mechanisms in order of strength from strong to weak are, the large-scale circulation pattern, sea-land distribution, vegetation, CO2 concentration, and earth orbital parameters.  相似文献   

Long-term ice sheet–climate interactions under anthropogenic greenhouse forcing simulated with a complex Earth System Model     

Miren Vizcaíno  Uwe Mikolajewicz  Matthias Gröger  Ernst Maier-Reimer  Guy Schurgers  Arne M. E. Winguth 《Climate Dynamics》2008,31(6):665-690

Several multi-century and multi-millennia simulations have been performed with a complex Earth System Model (ESM) for different anthropogenic climate change scenarios in order to study the long-term evolution of sea level and the impact of ice sheet changes on the climate system. The core of the ESM is a coupled coarse-resolution Atmosphere–Ocean General Circulation Model (AOGCM). Ocean biogeochemistry, land vegetation and ice sheets are included as components of the ESM. The Greenland Ice Sheet (GrIS) decays in all simulations, while the Antarctic ice sheet contributes negatively to sea level rise, due to enhanced storage of water caused by larger snowfall rates. Freshwater flux increases from Greenland are one order of magnitude smaller than total freshwater flux increases into the North Atlantic basin (the sum of the contribution from changes in precipitation, evaporation, run-off and Greenland meltwater) and do not play an important role in changes in the strength of the North Atlantic Meridional Overturning Circulation (NAMOC). The regional climate change associated with weakening/collapse of the NAMOC drastically reduces the decay rate of the GrIS. The dynamical changes due to GrIS topography modification driven by mass balance changes act first as a negative feedback for the decay of the ice sheet, but accelerate the decay at a later stage. The increase of surface temperature due to reduced topographic heights causes a strong acceleration of the decay of the ice sheet in the long term. Other feedbacks between ice sheet and atmosphere are not important for the mass balance of the GrIS until it is reduced to 3/4 of the original size. From then, the reduction in the albedo of Greenland strongly accelerates the decay of the ice sheet.  相似文献   

华北回流暴雪发展机理个例研究   总被引：23，自引：5，他引：18  

周雪松  谈哲敏 《气象》2008,34(1):18-26

利用新一代中尺度数值模式WRF对2004年11月24-25日发生在华北的一次回流暴雪过程进行了数值模拟,并着重对回流暴雪形成发展的机制进行了分析研究.在回流暴雪形成与发展的过程中,动力锋生机制发挥了重要作用;其产生的锋面次级环流是造成这次暴雪的主要原因;降水过程中,雨雪相态的转变与温度廓线有直接关系,随着降水由雨转为雪,雪水混合比增大迅速且其高度有所降低.地形在此回流暴雪过程中,通过其强迫的、分别位于迎风坡和背风坡的正负垂直速度中心,对降雪起明显的增幅作用,同时对雨水和云水分布产生影响.  相似文献   

热力强迫对局地环流的扰动作用   总被引：2，自引：0，他引：2       下载免费PDF全文

黄先伦  李国平 《应用气象学报》2008,19(4):488-495

用积分变换法求解了包含地面加热作用的二维不可压缩流体的Boussinesq方程组,得到一组描述地面加热作用激发的局地扰动流场的解析解,主要有垂直风、水平扰动风、扰动气压、扰动温度。进而用动力学分析的观点结合图形分析,定性讨论了热力强迫作用对局地环流的扰动作用,以及加热影响下各物理扰动场的空间分布及时间演变特征。  相似文献   

商丘市小麦白粉病预测模式研究     

余卫东  朱晓东  杨君健  刘伟昌 《河南气象》2008,31(1):20-23

以商丘市1995-2005年的小麦白粉病发病面积、地面气象资料和大气环流特征量为依据,利用相关系数法进行因子普查,筛选出了影响商丘市小麦白粉病发生和流行的主要地面气象因子和大气环流特征因子及其关键时段,并利用多元线性回归方法建立了数学预测模型,模型历史拟合准确率为95．2％。利用该预测模式在2006年和2007年对商丘市白粉病发病面积进行预测,预报精度分别为93．1％和90．2％。  相似文献   

2007年1月初河北省连续大雾的成因分析   总被引：2，自引：2，他引：0  

陈瑞敏  吴雁  刘晓峰  徐建芬 《干旱气象》2008,26(2):63-66

对发生在2007年元旦期间河北省大部地区的连续大雾天气从高低空环流形势、物理量场及气象要素场变化等方面进行了分析。发现这次大雾天气发生在500hPa中纬度平直偏西气流、中低层西北气流或弱高压环流以及地面高压前部弱气压场控制的大气环流形势下。大雾前期出现了明显降雪,雪后融化使近地面层湿度迅速增加;大雾期间,夜间辐射明显,近地层大气有逆温层结建立。水汽聚集在近地层通过地面蒸发和辐射冷却而达到饱和。充足的水汽和近地面明显的水汽饱和是河北大部分地区出现连续大雾的重要原因之一。而且这次大雾天气过程近地面层呈弱稳定状态,中高层为稳定状态。  相似文献