| 1 | Quantitative study on pollen-based reconstructions of vegetation history from central Canada显示文摘Based on high-resolution pollen records from lake cores in central Canada, the present study instructed pollen taxa assignations in ecosystem groups and modern analogue technique, reported major results of quantitative reconstructions of vegetation history during the last 1000 years, and discussed the validation of simulated vegetation. The results showed that in central America (115°-95°W, 40°-60°N), best analogue of the modern vegetation is 81% for boreal forest, 72% for parkland, and 94% for grassland-parkland, which are consistent with vegetation distributions of the North American Ecosystem II. Simulations of the past vegetation from the sedimentary pollen showed climate changes during the past 1000 years: it was warm and dry in the Medieval Warm period, cold and wet in the earlier period and cold and dry in the later period of the Little Ice Age. It became obviously increasing warm and drought in the 20th century. The present studies would provide us scientific basis to understand vegetation and climate changes during the last 1000 years in a characteristic region and in 10-100 year time scales. | HART Catherina VETTER Mary SAUCHYN David | 2008 | Science China Earth Sciences2008，51，8： | 2 |
| 2 | MM5 Simulations of the China Regional Climate During the Mid-Holocene显示文摘Using a regional climate model MM5 nested with an atmospheric global climate model CCM3,a series of simulations and sensitivity experiments have been performed to investigate responses of the mid-Holocene climate to different factors over China.Model simulations of the mid-Holocene climate change,especially the precipitation change,are in good agreement with the geologic records.Model results show that relative to the present day(PD)climate,the temperature over China increased in the mid-Holocene,and the increase in summer is more than that in winter.The summer monsoon strengthened over the eastern China north of 30°N,and the winter monsoon weakened over the whole eastern China;the precipitation increased over the west part of China,North China,and Northeast China,and decreased over the south part of China. The sensitive experiments indicate that changes in the global climate(large-scale circulation background), vegetation,earth orbital parameter,and CO_2 concentration led to the mid-Holocene climate change relative to the PD climate,and changes in precipitation,temperature and wind fields were mainly affected by change of the large-scale circulation background,especially with its effect on precipitation exceeding 50%.Changes in vegetation resulted in increasing of temperature in both winter and summer over China,especially over eastern China;furthermore,its effect on precipitation in North China accounts for 25%of the total change. Change in the orbital parameter produced the larger seasonal variation of solar radiation in the mid-Holocene than the PD,which resulted in declining of temperature in winter and increasing in summer;and also had an important effect on precipitation with an effect equivalent to vegetation in Northeast China and North China.During the mid-Holocene,CO_2 content was only 280×l0^(-6),which reduced temperature in a very small magnitude.Therefore,factors affecting the mid-Holocene climate change over China from strong to weak are large-scale circulation pattern,vegetation,earth orbital parameter,and CO_2 concentration. | 刘煜 何金海 李维亮 陈隆勋 李薇 张博 | 2010 | Acta meteorologica Sinica2010，24，4： | 1 |
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