两层原始方程海流数值模式和模拟

设计了一个两层原始方程海流数值模式，利用１月和７月多年平均的海平面气压场和由该气压诊断出的海面风场，对此模式的性能进行了检验，结果表明，模拟得出的海洋表层及次表层流与实况较为一致，文中还将模拟结果和ＩＡＰ ＯＧＣＭ以及ＯＳＵ ＯＧＣＭ的相庆结果作了初步比较和分析。     

反演台风海平面气压场与NCEP及报文资料的对比

利用QuikSCAT散射计获取的海面风场资料,借助UWPBL模式,对2006年3个台风个例的海平面气压场进行了反演。通过将反演结果与NCEP海平面气压场及台风报文资料的对比分析,表明反演的台风海平面气压场准确性较NCEP海平面气压场高,但与报文资料相比,中心气压明显偏高,因此这种利用散射计风场反演海平面气压的方法虽有一定的准确性,但精确度还有待提高。     

散射计和下投式探空仪资料对台风模拟的影响

为了评估同化QuikSCAT海平面气压场资料和Dropsonde资料对台风"Bilis"和"Kat-rina"模拟的影响,通过WRF-3DVAR变分同化系统将QuikSCAT海平面气压场资料和Dropsonde资料同化到WRF模式中,并以未同化任何资料和同化了QuikSCAT海平面气压场以及同化了Drop-sonde资料的数据为初始场,应用WRF模式进行模拟预报,并对得到的初始分析场和模拟预报得到的结果与台风实况报文进行了对比,得到的结论是:对台风初始时刻海平面气压场分布、初始台风中心定位、台风初始暖心结构的改善、台风路径、海平面最低气压场、海面最大风速和雷达回波的模拟方面,同化QuikSCAT海平面气压场的效果比同化Dropsonde资料明显,其中二者对海平面最低气压场的改进效果比海面最大风速的要好。但是两种资料的同化对初始相对湿度和台风强度细节变化方面都没有产生明显改善作用。同化QuikSCAT海平面气压场试验虽然仅仅同化了单层海平面气压场,但是在三维变分同化系统的动力约束作用下,也可以影响到中高层的各个要素场。     

理想海域中台风引起的潮、流及波的分析 I 开阔海域的情况

采用理论分析与数值计算相结合的方法研究了理想开阔海域中的台风暴潮模型,讨论了开阔海域中移行台风下的海洋响应。分析表明,在开阔的浅海域,台风下的海洋运动以地转流为主,同时又激发出振幅较小的重力惯性流。重力惯性波是由于台风强度或移速的突然变化引起的,其波速通常大于台风移速。台风气压场造成海面升高且基本符合“静压效应”,但产生的正压流场非常微弱。伴随强风的气旋性风场造成的海面下降在台风经过之后可以维持很长时间,从而在台风后面形成一个长达几百公里的尾迹。而台风风应力和气压梯度力的总效果是在台风正前方造成海面上升,正后方造成海面下降。     

月海平面气压场与我国汛期降水的若干统计关系及其在长期、超长期预报中的应用

用1月和7月全球海平面气压场与我国长江中下游和华北地区汛期降水进行了相关计算,计算表明,月海平面气压场在某些地区与汛期降水有显著相关关系,这些相关高值区往往与大气活动中心、洋流相联系。计算不但揭示了我国汛期降水与海平面气压的遥相关性而且表示长期天气有全球性的特征。     

近海面风场对黄东海域海平面特征影响的分析与模拟

基于1993—2012年TOPEX/Poseidon(T/P)卫星海平面异常SLA(Sea Level Anomaly)数据和FSCR(Climate Forecast System Reanalysis)再分析风场资料,分析黄东海域近20 a海平面的时空分布特征,尤其是不同时间尺度风场影响的变化特征,进而通过区域海洋模式对海面高度短期变化的可能机制进行探讨。结果表明:1)黄东海域海平面多年平均状态为南高北低,近海面季节性风场在岸线分布和海水热膨胀特征下,造成海面冬春季偏低,夏秋季偏高。近20 a黄东海域平均风速逐步减弱,平均海面上升速率为2.9 mm/a。2)风场的短期活动主要为灾害性大风,统计显示冬夏寒潮大风和台风大风均呈频数减少、强度增强的趋势。运用FVCOM(Finite Volume Community Ocean Model)模拟分析台风和寒潮作用下黄东海域海平面的变化,发现台风强风可形成辐散式海流气旋式涡旋,对应海面为下凹负值中心;北路寒潮大风可形成海流反气旋式涡旋,对应海面为上凸正值中心。两类涡旋的强海流部分增强了海面倾斜度。3)强海流部分动能和动量迅速向海水深部下传,无论在深度和强度上,寒潮造成的海流涡旋动能和动量下传比台风涡旋更迅速,更强。这与寒潮降温引起的海洋层结不稳定对流作用有关。     

用初始方程二层模式模拟一月和七月全球海平面气压场

用低分辨率的初始方程二层模式在给定下垫面温度下模拟了一月及七月全球海平面气压场,其中加热项主要是感热垂直输送。计算采用守恒的Lilly空间差分格式及Matsuno的时间差分格式。海平面气压的初值给成常数值,高空的风速及气温的初值给成纬向平均的气侯值。在数值模拟中,下垫面温度用一月及七月的气候实际值。计算的冬半球海平面气压与观测值相当一致,而夏半球的结果稍差些。本模式所求得的全球海平面气压场能与实况相比,结果并不差于高分辨率的复杂模式。     

一种新的台风海面风场的拟合方法

基于台风风场的经验风公式和修正的梯度风方程并考虑了台风气压场的非对称性,提出了一种新型的台风风场合成模式。经过对10多个不同类型热带气旋(台风)的检验,结果表明,新的模式可以模拟出各种强度及不同眼半径台风的海面风场,比以往常用模式能更真实地反映实际台风风场。     

基于海平面气压动力反演的台风涡旋初始化方法

提出了一种基于海平面气压动力反演和变分同化技术初始化数值模式台风涡旋以改进台风预报的方法。使用QuikSCAT海面风资料,针对中纬度和热带地区使用不同的边界层模式反演出与观测风场动力相适应的海平面气压;然后基于三维变分动力约束将海平面气压同化进入中尺度模式。对登陆中国的两个台风个例的初始化敏感性数值试验研究发现,初始化方法在实现台风风场与气压场的动力平衡的基础上,不仅通过调整边界层入流结构和垂直风切变明显改变了大气不稳定状态和对流触发条件,而且,也调整了台风在对流层顶附近的流出结构。尤其值得注意的是,尽管同化只是使初始台风强度略有加强,但随着模式积分时间的增长,这种模式边界层物理过程与资料同化相互耦合的方法对台风预报的影响在逐渐加强,改善了对台风登陆过程中强度维持和迅速减弱阶段的描述;并通过不同程度地调整对流层中低层和高层引导气流,改善了台风路径的数值模拟。     

自由表面海洋环流模式的正、斜压模分解算法

大气物理研究所海洋环流模式（IAP OGCM）特点之一是消除“刚盖”近似，引入海面起伏作为模式的预报变量。为此，需设计有效的时间积分方案，以克服模式中所保留的表面重力波对时间步长的苛刻限制。本文给出了适应过程中流场正压和斜压模分解算法。研究表明，把海洋模式适应过程进一步分解为与海面起伏相联系的正压模和与密度不均匀分布相联系的斜压模，用不同的时间步长数值求解，计算效率可提高数倍以上。文中用四层IAP OGCM在北太平洋区域定量地比较了节省计算时间的有效性，并给出数值计算实例。     

森林下垫面陆面物理过程及局地气候效应的数值模拟试验

文中基于大气边界层和植被冠层微气象学基本原理 ,建立了一个森林植被效应的陆面物理过程和二维大气边界层数值模式。并应用该模式进行了植被和土壤含水量等生物和生理过程在陆面过程和局地气候效应方面的数值模拟试验。所得数值模拟试验结果与实际情况相吻合。结果表明 ,应用该模式可获得植被温度、植被冠层内空气温度、地表温度日变化特征 ;森林下垫面大气边界层风速、位温、比湿、湍流交换系数的时空分布和日变化特征。该模式还可应用于不同下垫面 ,模拟陆面物理过程与大气边界层相互作用机制及其局地气候效应的研究 ,这将为气候模式与生物圈的耦合研究奠定一个良好的基础。     

陆面过程模式LPM-ZD及其对我国中东部地区陆面特征的模拟

该文利用陆面过程模式ＬＰＭ┐ＺＤ和一套观测分析资料对我国中东部地区的陆面特征进行了模拟研究．模拟结果表明：模式ＬＰＭ┐ＺＤ比较好地模拟了该区域内不同类型植被和土壤的温、湿变量以及陆气间通量交换的日变化特征；能够合理地模拟我国中东部区域的陆面过程特点分布，很好地反映了我国南北方区域气候特点的差异和我国夏季风气候特点     

ON THE RELATIONSHIP BETWEEN PLANETARY AND SURFACE ALBEDO:MODEL''''S COMPARISON AND VALIDATION

The simple linear relationship between clear-sky planetary and surface albedo can be adopted forcertain accuracy.There are different parameterization schemes of atmospheric correction for differentretrieval models.In this paper,several representative retrieval models are compared and tested withobservational data from HEIhe basin Field Experiment (HEIFE) in western China.Some evaluationsand suggestions on improvement are proposed for models which would be more applicable to plateauand arid areas.     

STUDY ON CLIMATIC FEATURES OF SURFACE TURBULENT HEAT EXCHANGE COEFFICIENTS AND SURFACE THERMAL SOURCES OVER THE QINGHAI-XIZANG PLATEAU

Using monthly mean of surface turbulent heat exchange coefficients calculated based on datafrom four automatic weather stations(AWS)for thermal equilibrium observation in July 1993—September 1996 and of surface conventional measurements,an empirical expression is establishedfor such coefficients.With the expression,the heat exchange coefficients and the components ofsurface thermal source are computed in terms of 1961—1990 monthly mean conventional data from148 stations over the Qinghai-Xizang(Tibetan)Plateau(QXP)and its adjoining areas,and the1961—1990 climatic means are examined.Evidence suggests that the empirical expression is capable of showing the variation of the heatexchange coefficient in a climatic context.The monthly variation of the coefficients averaged overthe QXP is in a range of 4×10~(-3)-5×10~(-3).The wintertime values are bigger in the mountainsthan in the valleys and reversal in summer.Surface effective radiation and sensible heat are thedominant factors of surface total heat.In spring surface sensible heat is enhanced quickly,resulting in two innegligible regions of sensible heat,one in the west QXP and the other innorthern Tibet.with their maximums emerging in different months.In spring and summersensible heat and surface effective radiation are higher in the west than in the east.The effectiveradiation peaks for the east in October—December and the whole QXP and in June and October forthe west.The surface total heat of the plateau maximizes in May.minimizes in December andJanuary,and shows seasonal variation more remarkable in the SW compared to the eastern part.Inthe SW plateau the total heat is much more intense than the eastern counterpart in all the seasonsexcept winter.Under the effect of the sensible heat,the total heat on the SW plateau starts toconsiderably intensify in February,which leads to a predominant heating region in the west,withits center experiencing a noticeable westward migration early in summer and twice pronouncedweakening in July and after October.However,the weakening courses are owing to differentcauses.The total heat over the north of QXP is greatly strengthened in March.thus generatinganother significant thermal region in the plateau.     

TROPICAL SEA SURFACE TEMPERATURE ANOMALY AND INDIAN SUMMER MONSOON

The time series of the sea surface temperature(SST)anomaly,covering the eastern(western)equatorial Pacific,central Indian Ocean,Arabian Sea.Bay of Bengal and South ChinaSea(SCS),have been analyzed by using wavelet transform.Results show that there exists sameinterdeeadal variability of SST in the tropical Pacific and tropical Indian Ocean,and also show thatthe last decadal abrupt change occurred in the 1970s.On the interannual time scale,there is asimilar interannual variability among the equatorial central Indian Ocean and the adjacent three seabasins(Arabian Sea.Bay of Bengal and South China Sea).but the SST interannual changes of theIndian Ocean lagged 4—5 months behind that of the equatorial central-east Pacific.Meanwhile,the interannual variability and long-range change between SST anomaly and Indian summermonsoon rainfall in recent decades have been explained and analyzed.It indicates that there existeda wet(dry)period in India when the tropical SST was lower(higher)than normal,but there wasa lag of phase between them.     

EFFECTS OF SEA SURFACE TEMPERATURE AND ITS DIURNAL VARIATION ON DIURNAL VARIATION OF RAINFALL: A PARTITIONING ANALYSIS BASED ON SURFACE RAINFALL BUDGET

The effects of sea surface temperature(SST) and its diurnal variation on diurnal variation of rainfall are examined in this study by analyzing a series of equilibrium cloud-resolving model experiments which are imposed with zero large-scale vertical velocity.The grid rainfall simulation data are categorized into eight rainfall types based on rainfall processes including water vapor convergence/divergence,local atmospheric drying/moistening,and hydrometeor loss/convergence or gain/divergence.The rainfall contributions of the rainfall types with water vapor convergence are insensitive to the increase in SST from 27°C to 29°C during the nighttime,whereas they are decreased during the daytime.The rainfall contributions of the rainfall types with water vapor convergence are decreased as the SST increases from 29°C to 31°C but the decreases are larger during the nighttime than during the daytime.The rainfall contributions of the rainfall types with water vapor convergence are decreased by the inclusion of diurnal variation of SST with diurnal difference of 1°C during the nighttime,but the decreases are significantly slowed down as the diurnal difference of SST increases from 1°C to 2°C.The rainfall contributions of the rainfall types with water vapor convergence are insensitive to the inclusion of diurnal variation of SST during the daytime.     

SENSITIVITY TESTS OF INTERACTION BETWEEN LAND SURFACE PHYSICAL PROCESS AND ATMOSPHERIC BOUNDARY LAYER

In this paper,an interactive model between land surface physical process and atmosphereboundary layer is established,and is used to simulate the features of soil environmental physics,surface heat fluxes,evaporation from soil and evapotranspiration from vegetation and structures ofatmosphere boundary layer over grassland underlying.The sensitivity experiments are engaged inprimary physics parameters.The results show that this model can obtain reasonable simulation fordiurnal variations of heat balance,soil volumetric water content,resistance of vegetationevaporation,flux of surface moisture,and profiles of turbulent exchange coefficient,turbulentmomentum,potential temperature,and specific humidity.The model developed can be used tostudy the interaction between land surface processes and atmospheric boundary layer in cityregions,and can also be used in the simulation of regional climate incorporating a mesoscalemodel.     

陆面过程模式的改进及其检验

文中对陆面过程模式 (BATS)进行了改进 ,改进后的模式能较好地模拟地表物理量的年、季和日变化 ,它有两方面的特点 :采用热扩散方程模拟 7层土壤温度 ,模拟的温度可与实测值进行比较 ;在BATS的地表径流方案中 ,考虑了空间不均匀性的一般地表径流 (GVIC)过程 ,研究结果表明 :⑴模式能很好地模拟各层土壤温度的年、季和日变化。冬季土壤温度下层高于上层 ,而在夏季上层高于下层 ,这种上下层温度的转换时间大约在 4和 10月份 ,这与实测土壤温度的年变化非常一致。较为准确地模拟了各层土壤温度日变化的时滞效应。⑵用南京和武汉站的资料 ,将BATS地表径流方案模拟的地表水分分量与GVIC方案进行比较 ,BATS地表径流方案模拟的地表水分分量 ,与总水量的平衡相差较大 ,而GVIC模拟的效果相对较好 ,地表总水量基本上与降水总量达到了平衡     

城市区域内建筑物墙体内外壁表面温度特征的比较研究

使用12月、4月、8月昆明城市区域内建筑物墙体内外壁表面温度的观测资料，分析了不同朝向墙体内外壁表面温度的特征、变化规律及差异。结果表明：4月和8月墙体内外壁表面温度较高，12月较低；不同朝向墙体之间的差异以天气晴朗的4月和12月较大，多云天8月最小；4月和8月E向墙体的内外壁表面温度均最大，S向次之，N向最小：而12月S向墙体的内外壁表面温度在一段时段内甚至超过了E向；内壁表面温度的日较差低于外壁表面，且其出现最高、最低温度的时间均较外壁表面有所延滞。