XiaoJing Jia 2015-3-24@HangZhou Influence of Forced Large-Scale Atmospheric Patterns on winter climate in China XiaoJing Jia 2015-3-24@HangZhou

Contents Background The tropical Pacific SST-related large-scale atmospheric patterns and its relationship to the wintertime SAT over China The Mechanisms Conclusion

El Niño

North Atlantic Oscillation（NAO) 这种加强或者减弱的北大西洋西风带直接影响到当地的生态系统和北大西洋地区的渔业市场。是北美和欧洲国家非常关心的问题。   4

Eighteen winter average temperature anomalies expressed as departures from the 1951 to 1980 mean. The temperature data consist of land surface temperatures blended with SST data (Jones and Briffa 1992). Negative anomalies are dashed, and regions of insufficient data coverage are not contoured. (Hurrell, 1996)

The relationship between PNA&NAO and the SAT over China (winter) (Jia and Lin, 2011)

Contents Background The tropical Pacific SST-related large-scale atmospheric patterns and its relationship to the wintertime SAT over China The Mechanisms Improving seasonal forecast skill using the large-scale pattens Coclusion

SVD - （Tropiacl Pacific SST- Z500_NH） TCC (PNA-ASVD1=0.67) TCC (NAO-ASVD2=0.81) - NAO-Like + Negative SSTA TCC (Nino3.4-SSVD1=0.97)

The relationship between SVD1 &SVD2 and the SAT over China (winter) NAO PNA

Contents Background The tropical Pacific SST-related large-scale atmospheric patterns and its relationship to the wintertime SAT over China The Mechanisms Improving seasonal forecast skill using the large-scale pattens Coclusion

SVD2 related atmospheric circulation SLP AO-SVD2=0.81 footer here

AL SH AL SH

SLP Vector:Wind_Z850 Shading: SAT Contour: SLP footer here

SLP Z500 footer here

SVD2 related atmospheric circulation footer here

surface Z500 Z200

SVD2 +  East Asian Winter Monsoon weak Warm China

SVD2 related EP flux Z200 Vector:EP flux ? footer here

SVD2 related precipitation + - - + footer here

Numerical Experiment (LBM) + - footer here

+ - footer here

Contents Background The tropical Pacific SST-related large-scale atmospheric patterns and its relationship to the wintertime SAT over China The Mechanisms Improving seasonal forecast skill using the large-scale pattens Coclusion

Model Data seasonal ensemble forecast from six coupled models ---- APCC/CliPAS Project (Wang et al. 2009; Lee et al. 2010) ---- ENSEM-BLES Project (Weisheimer et al. 2009)

SVD1 SVD2 (Jia and Lin, 2014)

TCC of PC1&PC2 between models and observations

SVD1和SVD2对中国冬季地面气温的关系 （模式集合预报结果）

Summary • The winter SAT over China is significantly influenced by the leading two atmospheric patterns related to the tropical Pacific SST anomalies, especially the SVD2. • In the positive phase of the SVD2 the EAWM is weaker-than-normal and the winter SAT over China is warmer-than-normal. • The spatial structure and the time variability of the SVD2 and its relationship to the winter SAT over China are reasonably captured by MME seasonal forecasts.

Summary • A post-processing method based on the relationship between these large scale atmospheric patterns can efficiently improve the models seasonal forecasts skill. • The improved seasonal forecast skill come smainly from the second SVD mode.

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