摘要
预测数值模式对于中期天气预报能力是集合预报的重要应用之一。为研究集合预报在中国区域中期时效(96～360h)预报技巧的预测能力,本文基于欧洲中期天气预报中心(ECMWF)全球集合预报系统2007—2011年500 hPa高度场和850hPa温度场预报数据,采取两种不同的离散度-预报技巧关系表征方法进行对比分析,结果表明:(1)以均方根误差为表征的预报技巧(RMS_(ENS))和离散度(SP_(RMSE))表现出季节循环特征,即冬(夏)季值高(低),这是大气内在性质的表现。而以距平相关为表征的预报技巧(AC_(ENS))和离散度(SP_(AC))没有显著的内在季节变化特征。(2)对比分析两种不同表征的离散度-预报技巧关系可知,以距平相关为表征的离散度-预报技巧关系更能反映中期时效的预报技巧,且850 hPa温度场较500 hPa高度场二者的相关性更好。(3)定量分析离散度-预报技巧关系表明,小离散度情况下更能体现高的预报技巧,但这种关系从96～360 h样本百分比下降了20%左右,而在大离散度情况下离散度-预报技巧关系相对弱一些,且随预报时效的延长样本百分比没有显著的降低。(4)样本统计显示中期各时效SP_(RMSE)和SP_(AC)二者一致的样本占59%～66%,并没有显示较高的一致性特征。上述分析结果为集合预报在中期时效预报技巧预测方面提供定性和定量的参考。
Predictive ability of numerical model for medium-term weather forecast is one of the important applications of ensemble forecast.To study the predictive ability of forecast skill of ensemble prediction in medium-term period(96-360 h) in China,our analysis applies forecast data covering the period 2007-2011 from ECMWF global ensemble prediction system and chooses 500 hPa geopotential height and 850 hPa temperature as the variables,and then a comparative analysis is carried out by two different measures of spread-skill relations.The results show that:(1) Forecast skill(RMS_(ENS)) and spread(SP_(RMSE)) represented by root mean square errors show a seasonal cycle,i.e.,winter(summer) is high(low),which is an inherent atmospheric property.However,the forecast skill(AC_(ENS)) and spread(SP_(AC)) represented by anomaly correlations have no clear inherent seasonal cycle.(2) By comparing the two different measures of spread-skill relations,it is known that the spread-skill relations represented by anomaly correlations can reflect forecast skill better in medium-term period forecast,and this spread-skill relations based on T850 is stronger than based on Z500.(3) Quantitative analysis of spread-skill relations indicates that good forecast skill can be reflected when spread is small,and this relationship declines about 20%from 96 to 360 h samples,while spread-skill relations is weaker in the case of large spread,and this relationship does not decrease significantly with the increase of the valid time of forecast.(4) Statistic data shows that samples of the consistency of SP_(RMSE) and SP_(AC) account for 59%to 66%in medium-term period,which does not show high consistency.The above analysis results can provide qualitative and quantitative reference for the forecast skill of ensemble prediction in medium-term forecast.
出处
《气象》
CSCD
北大核心
2014年第7期777-786,共10页
Meteorological Monthly
基金
公益性行业(气象)科研专项(GYHY201306002和GYHY20130613)
国家自然科学青年基金项目(41005031)共同资助
