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U-Net: A deep-learning method for improving summer precipitation forecasts in China
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作者 qimin deng Peirong Lu +1 位作者 Shuyun Zhao Naiming Yuan 《Atmospheric and Oceanic Science Letters》 CSCD 2023年第4期8-14,共7页
本研究应用了名为U-Net的深度学习方法来提高中国夏季(6–8月)降水的预报技能,预报时段为1981–2020年,预报提前期为一个月.将位势高度场,土壤湿度,海平面气压,海表面温度,海洋盐度和青藏高原积雪等变量作为模型输入,本文对美国NCAR气... 本研究应用了名为U-Net的深度学习方法来提高中国夏季(6–8月)降水的预报技能,预报时段为1981–2020年,预报提前期为一个月.将位势高度场,土壤湿度,海平面气压,海表面温度,海洋盐度和青藏高原积雪等变量作为模型输入,本文对美国NCAR气候预报系统第2版(CFSv2)的季节性预报结果进行了修正.结果显示,在验证集和测试集上,U-Net平均将原CFSv2预测的均方根误差分别减少了49.7%和42.7%.预报结果改善最大的地区是中国的西北,西南和东南地区.然而,同号率和时空相关系数没有得到明显改善,但仍与CFSv2的预测技巧持平.敏感性实验表明,土壤湿度是预测中国夏季降雨的最关键因素,其次是位势高度场.本研究显示了U-Net模型在训练小样本数据集方面的优势,为我国汛期季节性降雨预测提供了一种有效的深度学习方法. 展开更多
关键词 汛期降水 U-Net 次季节预报 深度学习
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Eigen microstates and their evolutions in complex systems 被引量:7
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作者 Yu Sun Gaoke Hu +6 位作者 Yongwen Zhang Bo Lu Zhenghui Lu Jingfang Fan Xiaoteng Li qimin deng Xiaosong Chen 《Communications in Theoretical Physics》 SCIE CAS CSCD 2021年第6期140-157,共18页
Emergence refers to the existence or formation of collective behaviors in complex systems.Here,we develop a theoretical framework based on the eigen microstate theory to analyze the emerging phenomena and dynamic evol... Emergence refers to the existence or formation of collective behaviors in complex systems.Here,we develop a theoretical framework based on the eigen microstate theory to analyze the emerging phenomena and dynamic evolution of complex system.In this framework,the statistical ensemble composed of M microstates of a complex system with N agents is defined by the normalized N×M matrix A,whose columns represent microstates and order of row is consist with the time.The ensemble matrix A can be decomposed as■,where r=min(N,M),eigenvalueσIbehaves as the probability amplitude of the eigen microstate U_I so that■and U_I evolves following V_I.In a disorder complex system,there is no dominant eigenvalue and eigen microstate.When a probability amplitudeσIbecomes finite in the thermodynamic limit,there is a condensation of the eigen microstate UIin analogy to the Bose–Einstein condensation of Bose gases.This indicates the emergence of U_I and a phase transition in complex system.Our framework has been applied successfully to equilibrium threedimensional Ising model,climate system and stock markets.We anticipate that our eigen microstate method can be used to study non-equilibrium complex systems with unknown orderparameters,such as phase transitions of collective motion and tipping points in climate systems and ecosystems. 展开更多
关键词 complex system phase transition critical phenomena Earth system statistical ensemble eigen microstate dynamic evolution ECONOPHYSICS
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