On the operational predictability of blocking
On the operational predictability of blocking
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DOI：
10.3402/tellusa.v42i3.11882
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发表时间：
1990-05
期刊：
影响因子：
--
通讯作者：
S. Tibaldi;F. Molteni
中科院分区：
文献类型：
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作者：
S. Tibaldi;F. Molteni
ECMWF业务分析和预报数据的整个7年档案被用来评估该中心的模式在大气阻塞的短期和中期预报中的技能。评估涵盖7100天的时间，从1980-81年至1986-87年所有冬季的12月1日至3月10日。勒让斯和奥克兰客观地带指数的一个稍微修改的版本被用来量化观测和预测阻塞的发生。分别对500 hPa位势高度场和欧洲-大西洋及太平洋阻塞场进行了研究。结果发现，阻塞频率被严重低估，在中期预测，该模型是，平均而言，合理的熟练，如果初始条件被阻止，但阻塞发作是不好的代表，如果它发生在几天以上的预测。这种无法进入阻塞状态对模型的系统误差有很大影响。DOI：10.1034/j.1600-0870.1990.t01-2-00003.x
The entire 7-year archive of ECMWF operational analysis and forecast data is used to assess the skill of the Centre's model in short- and medium-range forecasting of atmospheric blocking. The assessment covers 7100-day periods, from 1 December to 10 March of all winters from 1980-81 to 1986-87, inclusive. A slightly modified version of the Legenas and Okland objective zonal index is used to quantify both observed and forecast occurrence of blocking. The study is performed on 500 hPa geopotential height and on Euro-Atlantic and Pacific blocking separately. It is found that blocking frequency is severely underestimated in medium-range forecasts; the model is, on average, reasonably skilful if the initial conditions are blocked, but blocking onset is poorly represented if it occurs more than a few days into the forecast. This inability in entering the blocking regime has a substantial impact on the systematic error of the model. DOI: 10.1034/j.1600-0870.1990.t01-2-00003.x