北极海冰的厚度和面积变化对大气环流影响的数值模拟   总被引：13，自引：2，他引：13  

武炳义  黄荣辉  高登义 《气象学报》2001,59(4):414-428

文中利用中国科学院大气物理研究所设计的两层大气环流模式 ,模拟研究了北极海冰厚度和面积变化对大气环流的影响 ,尤其是对东亚区域气候变化的影响。模式中海冰厚度处理趋于合理分布 ,导致东亚冬、夏季风偏强 ,使冬季西伯利亚高压和冰岛低压的模拟结果更趋合理 ;另一方面 ,海冰厚度变化可以激发出跨越欧亚大陆的行星波传播 ,在低纬度地区 ,该行星波由西太平洋向东太平洋地区传播 ;海冰厚度变化对低纬度地区的对流活动也有影响。冬季北极巴伦支海海冰变化对后期大气环流也有显著的影响。数值模拟结果表明 :冬季巴伦支海海冰偏多 (少 )时 ,春季 (4～ 6月 )北太平洋中部海平面气压升高 (降低 ) ,阿留申低压减弱 (加深 ) ,有利于春季白令海海冰偏少 (多 ) ;而夏季 ,亚洲大陆热低压加深 (减弱 ) ,5 0 0 h Pa西太平洋副热带高压位置偏北 (南 )、强度偏强 (弱 ) ,东亚夏季风易偏强 (弱 )。  相似文献   

以黄淮海为例研究农田实际蒸散量   总被引：19，自引：0，他引：19  

王菱  倪建华 《气象学报》2001,59(6):784-794

以田间实验资料为基础 ,建立农田蒸散量和土壤相对含水量与潜在蒸散的函数关系。利用这种函数关系 ,计算黄淮海地区 ,在自然条件下农田蒸散量的变化。结果表明 ,黄淮海农田蒸散量的年变化呈双峰型 ,第一峰值出现在冬小麦抽穗开花期 ,第二高峰出现在夏玉米抽雄开花期。农田蒸散的区域分布趋势与自然降水分布相一致 ,在量值上约等于降水量的 84%  相似文献   

中国西北大旱年发生概率的统计推断   总被引：6，自引：7，他引：6  

栗珂  赵东  杨碧轩  郭宏武  高炬 《高原气象》2001,20(1):66-70

根据中国西北近500a旱涝等级资料，用Bernoulli试验等理论模式，对大旱年发生的概率特征进行了研究，得出大旱年发生的统计规律。在全球气候变暖的大背景下，给出了21世纪中国西北大旱年发生概率的统计推断结果。  相似文献   

The Impact Of Air-Flow Separation On The Drag Of The Sea Surface   总被引：2，自引：1，他引：2  

V. N. Kudryavtsev  V. K. Makin 《Boundary-Layer Meteorology》2001,98(1):155-171

An approach that allows assessment ofthe impact of air-flow separation (AFS) fromwave breaking fronts on the sea-surface drag is presented. Wave breaking fronts are modelled by the discontinuities of the sea-surface slope. It is assumedthat the dynamics of the AFS from wave breaking crests is similar to thatfrom the backward facing step. The form drag supported by an individualbreaker is described by the action of the pressure drop distributed alongthe forward face of the breaking front. The total stress due to the AFS isobtained as a sum of contributions from breaking fronts of different scales.Outside the breaking fronts the drag of the sea surface is supported by theviscous surface stress and the wave-induced stress. To calculate the stressdue to the AFS and the wave-induced stress a physical model of the wind-wavespectrum is used. Together with the model of the air flow described in termsof surface stresses it forms a self-consistent dynamical system for the seasurface-atmosphere where the air flow and wind waves are strongly coupled.Model calculations of the drag coefficient agree with measurements. It is shownthat the dimensionless Charnock parameter (roughness length normalized onthe square of the friction velocity and the acceleration of gravity)increases with the increase of the wind speed in agreement with fieldmeasurements. The stress due to the AFS normalized on the square of thefriction velocity is proportional to the cube of wind speed. At low windsthe viscous surface stress dominates the drag. The role of the form drag,which is the sum of the stress due to the AFS and the wave-induced stress, isnegligible. At moderate and high winds the form drag dominates. At windspeeds higher than 10 m s^-1 the stress supported by the AFS becomescomparable to the wave-induced stress and supports up to 50% of the totalstress.  相似文献   

Measured And Simulated Latent And Sensible Heat Fluxes At Two Marine Sites In The Baltic Sea     

Anna Rutgersson  Ann-Sofi Smedman  Anders Omstedt 《Boundary-Layer Meteorology》2001,99(1):53-84

In this study, turbulent heat flux data from two sites within the Baltic Sea are compared with estimates from two models. The main focus is on the latent heat flux. The measuring sites are located on small islands close to the islands of Bornholm and Gotland. Both sites have a wide wind direction sector with undisturbed over-water fetch. Mean parameters and direct fluxes were measured on masts during May to December 1998.The two models used in this study are the regional-scale atmospheric model HIRLAM and the ocean model PROBE-Baltic. It is shown that both models overestimate the sensible and latent heat fluxes. The overestimation can, to a large extent, be explained by errors in the air-water temperature and humidity differences. From comparing observed and modelled data, the estimated 8-month mean errors in temperature and humidity are up to 1 °C and 1 g kg^-1, respectively. The mean errors in the sensible and latent heat fluxes for the same period are approximately 15 and 30 W m^-2, respectively.Bulk transfer coefficients used for calculating heat and humidity fluxes at the surface were shown to agree rather well with the measurements, at least for the unstable data. For stable stratification, the scatter in data is generally large, and it appears that the bulk formulation chosen overestimates turbulent heat fluxes.  相似文献   

Microhydrodynamics of flotation processes in the sea surface layer     

Marianne Grammatika  William B. Zimmerman   《Dynamics of Atmospheres and Oceans》2001,34(2-4)

The uppermost surface of the ocean forms a peculiarly important ecosystem, the sea surface microlayer (SML). Comprising the top 1–1000 μm of the ocean surface, the SML concentrates many chemical substances, particularly those that are surface active. Important economically as a nursery for fish eggs and larvae, the SML unfortunately is also especially vulnerable to pollution. Contaminants that settle out from the air, have low solubility, or attach to floatable matter tend to accumulate in the SML.Bubbles contribute prominently to the dynamics of air–sea exchanges, playing an important role in geochemical cycling of material in the upper ocean and SML. In addition to the movement of bubbles, the development of a bubble cloud interrelates with the single particle dynamics of all other bubbles and particles. In the early sixties, several in situ oceanographic techniques revealed an “unbelievably immense” number of coastal bubbles of radius 15–300 μm. The spatial and temporal variation of bubble numbers were studied; acoustical oceanographers now use bubbles as tracers to determine ocean processes near the ocean surface. Sea state and rain noises have both been definitively ascribed to the radiation from huge numbers of infant micro bubbles [The Acoustic Bubble. Academic Press, San Diego].Our research programme aims at constructing a hydrodynamic model for particle transport processes occurring at the microscale, in multi-phase flotation suspensions. Current research addresses bubble and floc microhydrodynamics as building blocks for a microscale transport model. This paper reviews sea surface transport processes in the microlayer and the lower atmosphere, and identifies those amenable to microhydrodynamic modelling and simulation. It presents preliminary simulation results including the multi-body hydrodynamic mobility functions for the modelling of “dynamic bubble filters” and floc suspensions. Hydrodynamic interactions versus spatial anisotropy and size of particle clouds are investigated.  相似文献   

南海海平面高度年循环的特征   总被引：10，自引：0，他引：10  

Liu Qinyu  Jia Yinglai  Wang Xiaohu  Yang Haijun 《大气科学进展》2001,18(4):613-622

根据 ＴＯＰＥＸ／ ＰＯＳＥＩＤＯＮ－ＥＲＳ高度计提供的海平面高度异常资料和并行海洋气候模式（ＰＯＣＭ）模拟海平面高度资料，分析了南海海平面高度年循环特征。结果表明：ｌ月，３月和５月海平面高度的异常值分别与７月，９月，１１月的异常值相反。ｌ月（７月），深水海区与吕宋海峡的海平面高度为负（正）异常，在大部分陆架区和南海的西和南部，海平面高度为正（负）异常。在３月（９月），除海平面高度异常的量级已减少，且较小的ＳＳＨ正异常（负异常）出现在南海的中部以外，海平面高度异常的分布型与 １月（７月）类似； ＳＳＨ的年循环的最大振幅出现在吕宋岛的西北海域；风的季节变化是南海ＳＳＨ季节变化的主要原因。  相似文献   

印度洋偶极子对大气环流和气候的影响   总被引：28，自引：6，他引：28  

Li Chongyin  Mu Mingquan 《大气科学进展》2001,18(5):831-843

赤道印度洋SST的分析研究证实了偶极子型振荡的存在，它在9-11月较强而在1-4月较弱。若以海温西高东低为偶极子振荡正位相，以海温东高西低为负位相，则一般是正位相时振荡要强于负位相。印度洋偶极子也存在年际（主要周期为4－5年）和年代际（主要周期为25-30年）变化。分析研究表明，印度洋偶极子对亚洲季风活动有明显影响，因为亚洲地区对流层低层的风场，南亚高压和西太平洋副高强度都与印度洋偶极子有关。另外，印度洋偶极子还对北美和南印度洋（包括澳大利亚和南美）地区的大气环流和气流有影响。  相似文献   

西风爆发时赤道西太平洋的热量平衡：个例分析     

Liu Hailong  Zhang Xuehong  Li Wei 《大气科学进展》2001,18(5):882-896

The responses of sea surface temperature (SST) in the western equatorial Pacific warm pool to the west erly wind bursts (WWBs) play an important role in the relationship between WWB and ENSO. By using da ta collected from eight buoys of TOGA (Tropical Ocean-Global Atmosphere)-COARE (Coupled Ocean-Atmosphere Response Experiment), the heat balances of the upper ocean in the western equatorial Pacific around 0°. 156°E during two WWB events were calculated according to Stevenson and Niiler＇s (1983) method. In both events, SST increased before and after the WWBs, while decreased within the WWBs. The SST amplitudes approximated to l℃. Although sometimes the horizontal heat advections may become the biggest term in the heat balance, the variation of SST was dominated by the surface heat flux. On the other aspect, some different features of the two events are also revealed. The two cases have different variation of mixed layer depth. The depth of mixed layer is almost double in the first case (35 m to 70 m), which is caused by Ekman convergence, while only 10m increments due to entrainment in the second one. There are also differences in the currents structure. The different variations of thermal and currents struc ture in the mixing layers accounted for the different variation of the heat balance during the two events, es pecially the advection and residue terms. The seasonal variation of SST in this area is also investigated sim ply. The first WWB event happened just during the seasonal transition. So we considered that it is a normal season transition rather than a so-called anomaly. That also suggested that the seasonal distinction of the WWB is worthy of more attention in the researches of its relationship to ENSO.  相似文献   

强弱南海夏季风活动及大气季节内振荡   总被引：26，自引：0，他引：26  

Li Chongyin  Long Zhenxi  Zhang Qingyun 《大气科学进展》2001,18(6):1146-1160

应用ＮＣＥＰ再分析资料和中国降水资料，分析研究了对应南海强、弱夏季风的环流形势及其与之相应的中国东部的降水异常。其结果表明，由强、弱夏季风所引起的中国气候异常是完全不同（甚至反相）的。分析大气季节内振荡（ＩＳＯ）的活动还表明，对应大气强（弱）南海夏季风，南海地区 ８５０ ｈＰａ也有强（弱）大气 ＩＳＯ；而强、弱南海夏季风环流（２００ ｈＰａ和 ８５０ ｈＰａ）主要由异常的大气ＩＳＯ所激发。本研究还揭示了南海地区大气ＩＳＯ的变化往往与江淮地区大气ＩＳＯ的变化反相，例如南海地区的强（弱）大气ＩＳＯ常与江淮流域的弱（强）大气ＩＳＯ相对应。对于大气ＩＳＯ的强度，一般多表现出局地激发特征，经向传播相对较弱。  相似文献