【作者】 蒋国荣；

【导师】 何金海；

【作者基本信息】 南京信息工程大学 ， 气象学， 2006， 博士

【摘要】 论文主要通过诊断分析和数值模拟两种途径探讨了全球增暖背景下热带大气季节内振荡特征的可能变化。首先,利用近六十年NCAR/NECP再分析等资料诊断分析了在全球增暖气候背景下,热带大气季节内振荡的一些主要特征,如强度、活跃区范围、中心位置、季节变化、周期及传播特征可能发生的变化;发现,气候变暖,ISO活跃区的主要活动区位置不变,但ISO活跃区强度及范围均有不同程度的增大,并存在季节性差异,气候变暖有缩小ISO强度季节差异趋势;近几十年来,热带ISO强度总体呈现一个增强趋势:气候背景的改变也会影响热带大气季节内振荡传播特性,总体而言,近六十年来整个热带地区东传波相对增强,西传波则相对减弱;在不同气候背景下,季节内振荡的主周期范围也会发生变化,相对平稳阶段,季节内振荡能量小,季节内振荡周期相对集中(30～60天);偏暖阶段,季节内振荡能量大,但季节内振荡主周期相对分散(20～80天)。其次,分别利用中科院大气所LASG发展的FGOALS1.0_g耦合气候模式模拟的保持工业革命前的二氧化碳浓度不变(280ppm)的控制试验(自然变率)以及大气中二氧化碳浓度从工业革命前的280ppm以1%等比增加到560ppm的加倍试验(人类活动影响)的长期积分结果探讨了自然变率下与人类活动影响后热带大气季节内振荡的特征的变化。得出,近六十年来ISO主要活跃区的ISO强度增强、范围扩大及季节差异有缩小趋势等结论可能是大气ISO系统自身的年代际尺度变化,与人类活动影响导致温室气体增加所引起的全球气候变暖关联不大;自然变率下纬向东传波(西传波)的能量基本维持一种平衡状态,而人类活动影响下的纬向东传波(西传波)的能量则呈现出缓慢增长(减少)趋势,这与NCAR/NECP再分析资料分析结果一致,因此,近六十年来纬向东传波(西传波)的能量的增长(减少)趋势的结果可能是人类活动影响所致。最后,初步分析了热带大气季节内振荡特征变化与下垫面海温及热带大气环流系统的关联,得出,印度洋SST偶极子分布的变化对主要活跃区的大气ISO影响较大,并强于Nino3区的海温的作用。更多还原

【Abstract】 The possible changes of intraseasonal oscillation （ISO） feature in tropical atmosphere under the background of global climate warming by means of both diagnosis and numerical simulation are explored in this article. First, some main features possible changes of ISO in tropical atmosphere under the background of global climate warming, such as ISO intensity, central place of ISO chief active region, season change, and propagation feature, have been diagnosed using the last NCAR/NCEP reanalysis data about six year. It is found that the place of ISO main active region remain no change but their intensity and range increase and enlarge to a certain extend, and these changes have difference in season .There is a reductive tendency in season difference when global climate become warmer. The ISO intensity in tropical atmosphere totally appear a heightening tendency. The change of climate background also affect the propagation feature of ISO in tropical atmosphere. In general, the eastward-propagation ISO energy relatively increase but the westward-propagation ISO energy relatively weaken when the climate become warmer. There is also the difference in the period range of ISO under the different climate background. During the stage of relative stable, the ISO energy is relative small but the range of ISO main period is relatively concentrative （in 30～60 days）. During the stage of relative warming, the ISO energy is relative large but the range of ISO main period is relatively scatter （in 20～100 days）.Second, the possible changes of ISO feature in tropical atmosphere under the situation of simulative natural variability and anthropogenic impact are explored, using the long-range integration results both the control test which the CO₂ density maintain no change as the quantity before industrial revolution and the double test which the CO₂ density increase by 1% every year from 280ppm （the density before industrial revolution） to 560ppm. These results are simulated by a coupled GCM-- FGOALS1.0_g, which is developed in the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric physics（LASG）, Institute of Atmospheric physics（IAP）. It is showed that the conclusion that the ISO intensity increase ,the main active region range enlarge and ISO season difference reduce may be the the interdecadal variation of atmosphere intraseasonal oscillation system itself but not the cause that the climate become warmer because of CO₂ density increase in atmosphere. Under the state of simulative natural variability, the tropical eastward-propagation or westward-propagation ISO energy ratio on the whole maintain a equilibrium state, But the tropical eastward-propagation or westward-propagation ISO energy ratio appear a slow increasing tendency when thinking of anthropogenic impact, this is consistent with the conclusion diagnosed by means of the last NCAR/NCEP reanalysis data about six year, the last NCAR/NCEP reanalysis data about six year. So the conclusion that ISO energy of eastward/westward-propagation relatively increase/reduce my be caused by the CO₂ density increasing. Finally, the relation among the feature change of ISO in tropical atmosphere, ocean SST and tropical atmosphere circulation system are analyzed preliminarily. It is showed that the SSTdipole in Indian ocean affect the atmosphere ISO in main active region greater than the Nino3 SST.更多还原