夏季西太平洋副热带高压的客观定量化预测及其对汛期降水的指示

A study of objective and quantitative forecasting the western Pacific subtropical high and its indication for precipitation in summer over China

  • 摘要: 基于动力-统计相似预报原理,将模式误差动力统计预报方案应用于西太平洋副热带高压的客观定量化预测,通过交叉检验距平相关系数,筛选出对副热带高压区域的500 hPa高度场模式预报结果订正较好的因子作为前期关键因子集。对2003—2010年的副热带高压区域的500 hPa高度场进行了回报检验,结果显示该方案在数值模式预报结果基础上有了进一步提高,显示出较高的预测水平。在此基础上,从高度场预测结果中提取出与中国降水关系最为密切的两个典型副热带高压特征指数(脊线指数与西伸脊点指数),将其投影在二维平面上,并根据不同类型的副热带高压特征下对应的雨型分类特征得到预报年副热带高压所属类型下中国夏季降水的分布类型,多年检验结果表明,预测的投影类型所对应的降水合成分布与实况的降水具有较好的一致性,进一步验证此种副热带高压与雨型分类的合理性,达到通过副热带高压的定量化预测对夏季的旱涝分布形式进行预测的目的,为进一步提高汛期降水预测水平提供一种可能的思路。

     

    Abstract: Based on the basic principle of the dynamical analogue prediction, the optimal dynamic multi factor scheme is established to revise prediction errors. It is applied to predict the subtropical anticyclone in the western Pacific. The key prophase predictors for forecasting the subtropical anticyclone in summer were separated from the atmospheric circulation factors through the correlation analysis and the cross validating the anomaly correlation coefficients (ACC). Then we made the independent sample return test of 2003-2010, and the results show that the optimal dynamic multi factor schemes can help the numerical model improve the accuracy of prediction. Based on this, we extract the two typical indexes (the western ridge point and the ridge line index) for the prediction of subtropical anticyclone, which are able to represent the characteristics of the subtropical anticyclone. Then we project the two indexes on a two-dimensional plane and associate it with the statistical classification of the subtropical anticyclone. Furthermore, we get the summer precipitation distribution type of forecast years corresponding to the type of subtropical anticyclone. The result shows that the distributions of precipitation corresponding to the projection of the type of subtropical anticyclone are well consistent with the observations, indicating the rationality of this type of classification of the subtropical anticyclone and precipitation distribution. Based on this study we could further forecast the monsoon precipitation through the objective and quantitative prediction of the subtropical anticyclone and thus provide a possible scheme for improving the monsoon precipitation prediction skill.

     

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