Autumn rain in western China(ARWC) is a unique and significant precipitation phenomenon that occurs during the summer-to-winter transition of the atmospheric circulation. Using the fifth generation of global climate a...Autumn rain in western China(ARWC) is a unique and significant precipitation phenomenon that occurs during the summer-to-winter transition of the atmospheric circulation. Using the fifth generation of global climate and weather reanalysis data from the European Centre for Medium-Range Weather Forecasts and CN05.1 grid precipitation data, this study examined the anomalous characteristics and mechanisms of ARWC by combining the synergistic effect of the westerly jet and meridional wind. Over the past 60 years, ARWC has exhibited significant interdecadal and interannual variations, as well as a north-south seesaw pattern. The westerly jet index(meridional wind index) exhibited a negative(positive) correlation with precipitation in the northern autumn rain zone(NARZ), and a positive(negative) correlation with precipitation in the southern autumn rain zone(SARZ). The coupling of a weak meridional southerly wind with a southward westerly jet and a strong meridional southerly wind with a northward westerly jet are the two primary modes that synergistically influence the ARWC. These synergistic effects cause significant atmospheric changes throughout the troposphere. The contrasting circulation structure, temperature advection, vertical motion, and water vapor flux contributed to the opposite precipitation anomalies observed in the NARZ and SARZ. A new comprehensive index that reflects the coupled synergistic effect is proposed to characterize the anomalous changes in ARWC. This study improves the understanding of the anomalous characteristics and mechanisms of ARWC.展开更多
马登–朱利安振荡(Madden-Julian Oscillation,MJO)作为热带季节内变率的主要模态,其准确预测对于提升次季节预测能力至关重要。然而,MJO具有多尺度演变特征和高度非线性动力过程,现有预测方法在捕捉其复杂时空结构方面仍存在不足。为此...马登–朱利安振荡(Madden-Julian Oscillation,MJO)作为热带季节内变率的主要模态,其准确预测对于提升次季节预测能力至关重要。然而,MJO具有多尺度演变特征和高度非线性动力过程,现有预测方法在捕捉其复杂时空结构方面仍存在不足。为此,本文提出了一种融合多模态数据与时空特征的MJO预测模型(Multimodal data and Integrated Spatiotemporal features for MJO prediction,MISM)。该模型以历史实时多变量MJO指数(Real-time Multivariate MJO index,RMM)和多个气象因子作为联合输入,通过压缩激励模块、卷积模块和Swin Transformer模块构建空间特征提取模块,并引入自回归注意力机制实现非线性时间序列建模。实验结果表明,MISM模型的预测技巧可延伸至30 d以上,并在25 d以上的长期预测阶段表现优于传统的动力学和统计学方法。此外,本文利用显著性图对气象因子贡献区域进行分析,结果显示西太平洋及印尼群岛在不同提前期均呈现较高敏感性,海洋区域贡献普遍强于陆地。水汽和海温异常在短期与中期作用更突出,而低层风场和对流活动在长期阶段贡献较强,高层环流则在各时效保持稳定影响,体现了模型对MJO演变机制的识别能力。展开更多
基金National Natural Science Foundation of China(42030611)Second Tibetan Plateau Scientific Expedition and Research (STEP) Program (2019QZKK0103)。
文摘Autumn rain in western China(ARWC) is a unique and significant precipitation phenomenon that occurs during the summer-to-winter transition of the atmospheric circulation. Using the fifth generation of global climate and weather reanalysis data from the European Centre for Medium-Range Weather Forecasts and CN05.1 grid precipitation data, this study examined the anomalous characteristics and mechanisms of ARWC by combining the synergistic effect of the westerly jet and meridional wind. Over the past 60 years, ARWC has exhibited significant interdecadal and interannual variations, as well as a north-south seesaw pattern. The westerly jet index(meridional wind index) exhibited a negative(positive) correlation with precipitation in the northern autumn rain zone(NARZ), and a positive(negative) correlation with precipitation in the southern autumn rain zone(SARZ). The coupling of a weak meridional southerly wind with a southward westerly jet and a strong meridional southerly wind with a northward westerly jet are the two primary modes that synergistically influence the ARWC. These synergistic effects cause significant atmospheric changes throughout the troposphere. The contrasting circulation structure, temperature advection, vertical motion, and water vapor flux contributed to the opposite precipitation anomalies observed in the NARZ and SARZ. A new comprehensive index that reflects the coupled synergistic effect is proposed to characterize the anomalous changes in ARWC. This study improves the understanding of the anomalous characteristics and mechanisms of ARWC.
文摘马登–朱利安振荡(Madden-Julian Oscillation,MJO)作为热带季节内变率的主要模态,其准确预测对于提升次季节预测能力至关重要。然而,MJO具有多尺度演变特征和高度非线性动力过程,现有预测方法在捕捉其复杂时空结构方面仍存在不足。为此,本文提出了一种融合多模态数据与时空特征的MJO预测模型(Multimodal data and Integrated Spatiotemporal features for MJO prediction,MISM)。该模型以历史实时多变量MJO指数(Real-time Multivariate MJO index,RMM)和多个气象因子作为联合输入,通过压缩激励模块、卷积模块和Swin Transformer模块构建空间特征提取模块,并引入自回归注意力机制实现非线性时间序列建模。实验结果表明,MISM模型的预测技巧可延伸至30 d以上,并在25 d以上的长期预测阶段表现优于传统的动力学和统计学方法。此外,本文利用显著性图对气象因子贡献区域进行分析,结果显示西太平洋及印尼群岛在不同提前期均呈现较高敏感性,海洋区域贡献普遍强于陆地。水汽和海温异常在短期与中期作用更突出,而低层风场和对流活动在长期阶段贡献较强,高层环流则在各时效保持稳定影响,体现了模型对MJO演变机制的识别能力。
