T63L16气候模式预报能力的空间尺度分布研究  

Distributions of prediction capacity of T63L16 model for mediumrange forecast at different spatial scales.

作　　者：许晓光[1,2] 李维京[2] 任宏利[2] 张培群[2] 

机构地区：[1]兰州大学大气科学学院,兰州730000 [2]中国气象局国家气候中心气候研究开放实验室,北京100081

出　　处：《气象学报》2009年第6期992-1001,共10页Acta Meteorologica Sinica

基　　金：国家科技支撑计划项目(2006BAC02B04和2007BAC29B03);国家自然科学基金项目(40805028;40675039和40575036);国家重点基础研究发展计划973计划(2006CB403606);公益性行业(气象)科研专项(GYHY200806005)

摘　　要：采用球谐谱展开和方差分析方法,利用1970—2003年NCEP再分析500 hPa高度场资料和国家气候中心T63L16月动力延伸预报业务回报1982—2002年的结果,研究了T63L16模式逐日预报可预报能力的空间尺度依赖特征和对于中期预报的可预报稳定分量。分析表明,T63L16模式预报能力在总波数n上具有各向同性,其主要的误差发生在波数为5—10的天气尺度波。基于对T63L16气候模式500 hPa位势高度场球谐系数内部方差和该物理量气候外部方差之比R演变特征的分析,本文定义了模式26—40 d预报的方差比的平均作为R的临界值来定量地确定T63L16模式对不同空间尺度气象场的可预报期限,并引入波能谱为权重系数研究了模式可预报期限与纬向波数和总波数的关系。结果显示该模式的逐日可预报期限与纬向波数和总波数、以及季节均有关系。可预报期限在整体上随着空间尺度的减小而逐渐缩短,但并不是纯粹的单调递减;对于纬向2波分量的可预报期限比3—5波要短,可能是由于该模式对表征东亚大槽和北美大槽的2波的刻画相对不够好。另外,对季节平均的中期预报可预报稳定分量的考察表明,就全球而言,对于提前6 d以上的预报,夏季具有的可预报稳定分量为纬向波数小于12或总波数在17以内,其他季节为纬向波数小于7或总波数小于13;对于提前11—15 d的预报,冬夏两季的可预报稳定分量为纬向波数小于5或总波数小于10,春(秋)季节为纬向波数小于3(2)或总波数不大于8(7)。这为针对该尺度发展新的预报策略和方法、改进预报效果,提供了依据。The 500 hPa geopotential height fields of NCEP（National Centers for Enviornmental Prediction） reanalysis data from 1970 to 2003 and hindcasting results from 1982 to 2002 derived from Monthly Dynamic Extended Range Forecast System of National Climate Center（T63L16 Model） were analyzed by the spherical harmonic expansion and variance analysis to the spherical harmonie coefficients.Spatial scale-dependence of day-to-day forecast capacity of T63L16 model and predicable stable components for midium-range forecast were studied.The results suggest that capacity of the model prediction is rather isotropic in total wave number n,and the main errors happen at total wave number from 5 to 10,or synoptic-scale wave.Based on analyzing the evolution of the ratio of T63L16 model internal variance to climatic external variance,an effective scale-dependent ratio threshold was defined which is the average of ratio for 26 - 40 day prediction to quantitatively decide the predictable limits of T63L16 model for a variety of spatial scales. Furthermore,a set of rational weight coefficients which represent wave energy spectrum were introduced to study the relationship between predictable limits of the model and latitudinal wave number m,as well as total wave number n.The results indicate that the day-to-day predictable limits of the T63L16 model are relevant to the zonal and total wave number,as well as the seasons.It was shown that predicable limits,as a whole,gradually shorten with spatial scale reduction,but the variation is not completely monoton-ic： the limits at latitudinal wave number of 2 are shorter than that between 3 and 5.In addition,the seasonal averaged predicable stable components to midium-range forecast were examined.As far as global mean is concerned,for above 6 day forecast,the predictable stable components are zonal wave number smaller than 12/7（or total wave number smaller than 17/13） in summer/other seasons, while for 11-15 day forecast,predictable stable components are zonal wave number smaller than 5

关 键 词：预报能力 中期预报 方差分析 可预报稳定分量 

分 类 号：P435[天文地球—大气科学及气象学]