Rainfall and temperature in China

Based on the corresponding Chinese climates for the four types of Fig. 2, we can easily find the influences of all SSTA patterns on climate are quite different. Because of long duration of SSTA, our results can provide some base for Chinese summer climate prediction. Because of the finite time length of observation data, the cases for composite analyzing are slightly small. However they, to a certain extent, explain the considerable effects of SSTA patterns on East China rainfall. Figure 3 shows the summer rainfall anomalies in East China corresponding to the four types of SSTA distribution in Fig. 2, respectively. Corresponding to the quasi-normal phase of the Pacific SSTA, more rainfall can be found in the coastal regions of

China Monsoon Region

Fig. 3. Composite of summer (JJA) precipitation anomaly in China for the quasinormal phase of ENSO mode (a), the quasi-normal phase of the PIM (b), the positive phase (El Nino) ofthe ENSO mode (c), the positive phase ofthe PIM (d). Unit: mm/JJA. The dark shading and light shading show the i-test significance at the 0.05 and 0.1 levels, respectively.

Fig. 3. Composite of summer (JJA) precipitation anomaly in China for the quasinormal phase of ENSO mode (a), the quasi-normal phase of the PIM (b), the positive phase (El Nino) ofthe ENSO mode (c), the positive phase ofthe PIM (d). Unit: mm/JJA. The dark shading and light shading show the i-test significance at the 0.05 and 0.1 levels, respectively.

south and southeast China, the Changjiang-Huaihe River Basin, and the southern part of North China, but less rainfall is observed from south of the Changjiang River to Yunnan Province (Fig. 3(a)). Corresponding to the quasi-normal phase of the Pacific-Indian Ocean, south of the Changjiang River, North China and the southern part of Northeast China receive less rainfall, and the areas from the Changjiang-Huaihe River Basin to Sichuan Province record more rainfall (Fig. 3(b)). Corresponding to the pure El Nino year, there is more rainfall in the Changjiang-Huaihe River Basin and Northeast China, less rainfall to the south of Changjiang River (Fig. 3(c)). Corresponding to the positive phase of the PIM, we can find more rainfall in southeast China coastal region and from the Changjiang-Huaihe River Basin to Sichuan Province, and less rainfall in North China and Northeast China (Fig. 3(d)). Comparing Fig. 3(a) with Fig. 3(b), and Fig. 3(c) with Fig. 3(d), it clearly indicates that on the summer rainfall in

Fig. 4. Surface air temperature anomaly in China (unit: °C), with the rest being the same as Fig. 3.

China, the impacts of the pure Pacific SSTA are very different from the composite impacts of the Pacific-Indian Ocean SSTA.

In a similar way, Fig. 4 illustrates, respectively, the surface air temperature anomalies in East China for the four types of SSTA distributions of Fig. 2, featuring that corresponding to the quasi-normal year of the Pacific SSTA, the Changjiang-Huaihe River Basin gets noticeable positive temperature anomaly (Fig. 4(a)); corresponding to the quasi-normal year of the Pacific-Indian Ocean SSTA, South China receives remarkable positive temperature anomaly (Fig. 4(b)); corresponding to the pure El Ninño year, Northeast China accepts substantially negative temperature anomaly; corresponding to the positive phase of the Pacific-Indian Ocean temperature anomaly mode, the middle-low region of the Changjiang River is controlled by negative temperature anomaly, and North China and the southern part of Northeast China have positive temperature anomaly (Fig. 4(d)). Evidently, the results indicate that the impacts of the pure Pacific SSTA on the summer temperature in East China are also different from those of the Pacific-Indian Ocean SSTA composite mode. In the summer of 2003, persistent severe hot weather has occurred in large areas of South China. The main reason is that the Pacific-Indian Ocean SSTA remains a quasi-normal state.24

Previous researches of the influence of El Niño on summer climates in China already showed that during El Niño year, more rainfall above average occurred in the Changjiang-Huaihe River Basin,25'26 and low temperature and more rainfall in Northeast China.27'28 Our results involving the pure El Ninño are almost the same as those previously researched. Consequently, we can conclude that the analyses in this section are credible to a certain degree.

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