Western Pacific Jet Stream Anomalies at 200 hPa in Winter Associated with Oceanic Surface Heating and Transient Eddy Activity   总被引：3，自引：3，他引：3       下载免费PDF全文

REN Xuejuan  ZHANG Yaocun 《Acta Meteorologica Sinica》2007,21(3):277-289

The relationships between the 200-hPa westerly jet stream anomalies over the East Asian coastal water- western Pacific(WPJS),and the oceanic surface heating and synoptic-scale transient eddy(STE)activity anomalies over the North Pacific in wintertime are examined by using ERA-40 and NCEP/NCAR reanalysis data.The analysis demonstrates that the surface heating and the STE anomalies have different patterns, corresponding to the three WPJS anomalous modes,respectively.In the first WPJS anomalous mode,the WPJS main part shows no robust anomaly.The anomalous westerly wind,occurring over the mid-latitude central-eastern Pacific past the date line is associated with the anomalous heating presenting both in the tropical central-eastern Pacific past the date line and the center of the North Pacific basin.Meanwhile,the STE anomaly appears around the region of the anomalous zonal wind.The fluctuation in jet strength shown in the second WPJS mode is strongly related to the heating anomaly in the Kuroshio Current region and the STE anomaly in the jet exit region.The third mode demonstrates a northward/southward shift of the WPJS,which has a statistical connection with a south-north dipolar pattern of the heating anomaly in the western North Pacific separated at 35°N.Meanwhile,the STE spatial displacement is in conjunction with jet shifts in the same direction.The heating anomaly has a close connection with the atmospheric circulation, and thus changes the mid-latitude baroclinicity,leading to the STE anomaly,which then reinforces the WPJS anomaly via internal atmospheric dynamics.  相似文献   

孟加拉湾季风爆发对南海季风爆发的影响Ⅰ:个例分析   总被引：11，自引：4，他引：11       下载免费PDF全文

刘屹岷  陈仲良  毛江玉  吴国雄 《气象学报》2003,61(1):1-9

利用南海季风试验分析场和NCAR向外长波辐射通量(OLR)资料研究了1998年孟加拉湾季风和南海季风爆发期间副热带环流的大尺度和天气尺度特征,探讨了孟加拉湾季风爆发与南海季风爆发之间的物理联系及孟加拉湾季风气旋的对流凝结潜热释放对副热带高压“撤出”南海的影响。结果表明,1998年5月爆发的东亚季风展现出典型的从孟加拉湾地区东传发展到南海地区的过程。随着孟加拉湾季风爆发和对流活动增强、北移,南海北部出现了低层西风和对流活动,领先于副热带高压在南海地区减弱和撤退。结果还显示南海北部地区的对流凝结加热有助于该地区经向温度梯度的反转,在热成风关系的制约下南海上空副热带高压脊面的垂直倾斜由冬季型转向夏季型,季风爆发。  相似文献   

A Laboratory Model for the Flow in Urban Street Canyons Induced by Bottom Heating   总被引：2，自引：2，他引：2  

LIU Huizhi  LIANG Bin  ZHU Fengrong  ZHANG Boyin  SANG Jianguo 《大气科学进展》2003,20(4):554-564

Water tank experiments are carried out to investigate the convection flow induced by bottom heating and the effects of the ambient wind on the flow in non-symmetrical urban street canyons based on the PIV (Particle Image Visualization) technique. Fluid experiments show that with calm ambient wind,the flows in the street canyon are completely driven by thermal force, and the convection can reach the upper atmosphere of the street canyon. Horizontal and vertical motions also appear above the roofs of the buildings. These are the conditions which favor the exchange of momentum and air mass between the street canyon and its environment. More than two vortices are induced by the convection, and the complex circulation pattern will vary with time in a wider street canyon. However， in a narrow street canyon， just one vortex appears. With a light ambient wind, the bottom heating and the associated convection result in just one main vortex. As the ambient wind speed increases, the vortex becomes more organized and its center shifts closer to the leeward building.  相似文献   

1998年夏季青藏高原及其邻近地区地面总热源季节变化特征及其与西太平洋副热带地区对流的关系   总被引：3，自引：0，他引：3  

LI Wei  CHEN Longxun 《大气科学进展》2003,20(3):343-348

利用98’TIPEX实验资料、1998年5-8月青藏高原6个自动热量平衡站(AWS)资料、青藏高原常规观测资料、中国300多个站的逐日降水资料、国家卫星中心接收的1998年5-8月OLR和日本GMS的TBB资料,研究了1998年5-8月青藏高原及其邻近地区逐日地面总热源的季节变化特征及其与西太平洋副热带地区对流的关系。结果表明:高原地面总热源与高原雨季开始有密切关系,高原雨季开始以后,高原平均的地面总热源明显减小;高原平均的地面总热源与20—30°N附近的西太平洋副热带地区的TBB有很好的负相关关系,表明高原地面总热源可以通过某种机制影响副热带地区的对流。  相似文献   

青藏高原地表热源异常与四川盆地夏季降水的关联   总被引：2，自引：1，他引：2       下载免费PDF全文

陈忠明  闵文彬  刘富明 《气象》2003,29(5):9-12

利用所计算的1961—1995年高原热源资料、四川与重庆的降水资料以及500hPa月平均高度场资料，分析了高原地表热源异常对四川盆地降水与旱涝的影响。结果表明，高原地表热源异常与四川盆地降水和旱涝有显著的相关；高原地表热源异常通过强迫500hPa东亚大气环流异常来影响四川盆地降水。  相似文献   

天然含钒金红石加热、淬火及电子辐射改性实验研究   总被引：4，自引：5，他引：4       下载免费PDF全文

刘娟鲁安怀  郭延军李宁  李巧荣郑佳 《岩石矿物学杂志》2003,22(4):339-344

天然含钒金红石样品经过1273K加热、淬火和高能电子辐照处理后性质发生不同程度的变化。XRD谱峰显示处理前后样品没有发生物相变化，显微IR图谱证明原样、加热、淬火样品的表面有少量吸附水存在，而辐射样品的显微IR图谱上没有检测到吸附水的吸收峰。用XPS分析比较了处理前后样品表面主要元素Ti、O和V的价态及含量，结果表明，原样经过处理后表面钒和氧的原子百分含量增加，其中淬火样品表面吸附水和钒的含量相对于原样增加最为明显，光催化活性相应较高；加热样品表面的吸附水和钒的含量比原样稍有增加，光催化活性与原样相当；电子辐射样品表面钒的原子百分含量相对原样增加不明显，而对水的吸附能力相对原样较低，光催化效率也略低。  相似文献   

由膨润土提铝残渣直接合成五配位体有机硅化合物     

于少明  周爱萍  陆亚玲  李忠 《矿物学报》2003,23(4):355-358

研究了以膨润土提铝残渣为原料，采用低温加热法直接合成有机硅化合物新方法。由实验确定了最佳的合成条件。用红外光谱法和X射线衍射法分析了合成产物的结构。结果表明，当以碱金属氢氧化物为介质时，合成的产物为五配位体有机硅化合物；在最佳合成条件下，钠盐和锂盐的收率分别为63．0％和44．9％。  相似文献   

An improvement of the mass flux convection parameterization scheme and its sensitivity tests for seasonal prediction over China   总被引：1，自引：1，他引：0  

PING Fan  GAO Shouting  WANG Huijun 《大气科学进展》2003,20(6):978-990

A modified cumulus parameterization scheme, suitable for use in a seasonal forecast model, is presented. This parameterization scheme is an improvement of the mass flux convection scheme developed by Gregory and Rowntree (1989; 1990). This convection scheme uses a “bulk” cloud model to present an ensemble of convective clouds, and aims to represent shallow, deep, and mid-level convection. At present,this convection scheme is employed in the NCC T63L20 model (National Climate Center, China Meteorological Administration). Simulation results with this scheme have revealed some deficiencies in the scheme,although to some extent, it improves the accuracy of the simulation. In order to alleviate the deficiencies and reflect the effect of cumulus convection in the actual atmosphere, the scheme is modified and improved.The improvements include (i) the full estimation of the effects of the large-scale convergence in the lower layer upon cumulus convection, (ii) the revision of the initial convective mass flux, and (iii) the regulation of convective-scale downdrafts. A comparison of the results obtained by using the original model and the modified one shows that the improvement and modification of the original convection scheme is successful in simulating the precipitation and general circulation field, because the modified scheme provides a good simulation of the main features of seasonal precipitation in China, and an analysis of the anomaly correlation eoetfieient between the simulation and the observations confirms the improved results.  相似文献   

Cases-97: Late-Morning Warming And Moistening Of The Convective Boundary Layer Over The Walnut River Watershed     

Margaret A. LeMone  Robert L. Grossman  Robert T. Mcmillen  Kuo-Nan Liou  S.C. Ou  Stuart Mckeen  Wayne Angevine  Kyoko Ikeda  Fei Chen 《Boundary-Layer Meteorology》2002,104(1):1-52

Aircraft, radiosonde, surface-flux, and boundary-layer windprofiler data from the Cooperative Atmosphere Surface Exchange Study's 1997 field project, CASES-97, are combined with synoptic data to study the evolution of the vertically-averaged mixed-layerpotential temperature []and mixing-ratio [Q] onthree nearly-cloudless days from 1000 CST to 1200CST (local noon is approximately 1230 CST). This was achieved through examination of the terms in the time-tendency (`budget')equations for []and [Q]. We estimate three of the terms –local time rate of change, vertical flux divergence, andhorizontal advection. For the [Q]-budget, vertical flux divergence usually dominates, buthorizontal advection is significant on one of the three days. The [Q]-budget balances for two of the three days to within the large experimental error. For the -budget,vertical flux divergence accounts for most of the morningwarming, with horizontal advection of secondary importance.The residual in the -budget has the same sign for all three days, indicating that not all the heating is accounted for. We can balance the []-budgets to within experimental error on two of the three days by correcting the vertical-flux divergence for apparent low biases in the flux measurements of one of the aircraft and in the surface fluxes, and accounting for direct heating of the mixed layer by radiative flux divergence allowing for the effects of carbonaceous aerosols. The [];-budget with these corrections also balances on the third day if horizontal gradients from synoptic maps are used to estimate the horizontal advection. However, the corrected budget for this day does not balance if the horizontal gradient in the advection term is estimated using CASES-97aircraft and radiosondes; we suggest that persistent mesoscale circulations led to an overestimate of the horizontal gradient andhence horizontal advection.  相似文献   

地面感热对青藏高原低涡流场结构及发展的作用   总被引：31，自引：9，他引：22  

李国平  赵邦杰  杨锦青 《大气科学》2002,26(4):519-525

考虑热带气旋类青藏高原低涡为受加热和摩擦强迫并满足热成风平衡的轴对称涡旋系统,通过求解线性化的柱坐标系中涡旋模式的初值问题,分析了地面感热对高原低涡流场结构及发展的影响,给出了高原低涡眼壁内、外侧水平流场和垂直流场的结构特征,讨论了低涡发展与其水平尺度、垂直厚度、所处纬度以及热量总体输送系数和加热强度的关系.结果表明:地面感热对低涡的生成及发展具有重要作用,但这种作用是否有利于低涡的发展与低涡中心和感热加热中心的配置有关.  相似文献