In this study, a 2000-year simulation forced by transient, external forcings is carried out with the Community Earth System Model. The authors investigate the spatiotemporal features of climate change in the Han Dynasty (1–200 A.D.) using the empirical orthogonal function (EOF) method. The leading EOF mode of the annual mean temperature anomalies shows a uniform variation of temperature over the whole of China, while the second EOF mode indicates opposite variations of temperature between western and eastern China. For the annual mean precipitation anomalies, the first EOF mode indicates a meridional dipole pattern over eastern China, with increased (decreased) precipitation to the south of the Yangtze River and decreased (increased) precipitation to the north. The leading mode of the 850 hPa winds and sea level pressure in summer exhibits a southwesterly (northeasterly) anomaly over South China, which is associated with a strengthened (reduced) meridional sea level pressure gradient. Compared to reconstructions, the model can capture the majority of features of climate changes in the Han Dynasty, though it underestimates the magnitude.
基于重建的太阳辐射、温室气体、火山活动和植被覆盖，利用全球耦合模式CESM，开展了一个过去两千年的模拟试验，并着重探讨了东汉时期（1?200 A.D.）中国气候的时空演变。中国年平均气温异常的EOF第一模态呈现出全国普遍增温/降温的空间型，而第二模态表现为中国东、西部气温变化相反的空间型。年平均降水异常的EOF第一模态呈现出一个经向偶极子型态：长江以南降水增加（减少）而长江以北降水减少（增加）。夏季风场异常的EOF第一模态表现为中国南方存在一个显著的西南风（东北风）异常，这主要归因于加强（减弱）的经向气压梯度。