Characteristics of decadal-centennial-scale changes in East Asian summer monsoon circulation and precipitation during the Medieval Warm Period and Little Ice Age and in the present day

Using meteorological observations, proxies of precipitation and temperature, and climate simulation outputs, we synthetically analyzed the regularities of decadal-centennial-scale changes in the summer thermal contrast between land and ocean and summer precipitation over the East Asian monsoon region during the past millennium; compared the basic characteristics of the East Asian summer monsoon (EASM) circulation and precipitation in the present day, the Little Ice Age (LIA) and the Medieval Warm Period (MWP); and explored their links with solar irradiance and global climate change. The results indicate that over the last 150 years, the EASM circulation and precipitation, indicated by the temperature contrast between the East Asian mainland and adjacent oceans, had a significant decadal perturbation and have been weaker during the period of rapid global warming over the past 50 years. On the centennial time scale, the EASM in the MWP was strongest over the past 1000 years. Over the past 1000 years, the EASM was weakest in 1450-1570. When the EASM circulation was weaker, the monsoon rain belt over eastern China was generally located more southward, with there being less precipitation in North China and more precipitation in the Yangtze River valley; therefore, there was an anomalous pattern of southern flood/northern drought. From the 1900s to 1920s, precipitation had a pat- tern opposite to that of the southern flood/northern drought, with there being less precipitation in the Yangtze River valley and more precipitation in North China. Compared with the case for the MWP, there was a longer-time-scale southern flood/northern drought phenomenon in 1400-1600. Moreover, the EASM circulation and precipitation did not synchronously vary with the trend of global temperature. During the last 150 years, although the annual mean surface temperature around the world and in China has increased, the EASM circulation and precipitation did not have strengthening or weakening trends. Over the past 1000 years, the weakest EASM occurred ahead of the lowest Northern Hemispheric temperature and corresponded to the weakest solar irradiance.     

纳米伦理: 研究现状、问题与挑战

20 世纪90 年代以来, 伴随着纳米科学与技术的蓬勃发展, 有关纳米技术的社会和伦理问题的研究悄然兴起并逐渐成为一门跨学科的研究领域. 本文主要从纳米伦理研究的兴起、纳米伦理研究的主要内容、以及纳米伦理研究所面临的挑战与应对等三个方面评述纳米伦理研究的现状、存在的问题以及未来发展的方向.     

双容水槽微机控制系统显示软件设计

结合软件工程的思想,根据微机控制系统对显示的基本要求,在集散系统特点的基础上设计出一套适于实验室控制系统的图形显示软件并用VisualC ＋实现,并在PC总线控制机上调试通过。     

煎炸油中自由基的电子自旋共振(ESR)研究

用ESR法测定了三种煎炸油(豆油、菜油、棉籽油)中的自由基。结果表明,炸油中自由基浓度随油温的升高和加热时间的增长而增加,在200℃左右自由基浓度激增。煎炸油中自由基寿命相当长。     

检验检测科学仪器发展现状及建议

 介绍了检验检测科学仪器的行业现状，梳理了全球检验检测科学仪器的发展特点和趋势，分析了中国在该领域的发展现状、面临的机遇及存在的问题，提出了相应的发展建议。