北半球夏季亚洲-北太平洋间大气质量迁移规律及其与气候异常的联系
投稿时间: 2016-04-19  最后修改时间: 2016-05-11  点此下载全文
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作者单位E-mail
尹旸艳 南京信息工程大学 442788607@qq.com 
管兆勇 南京信息工程大学 guanzy@nuist.edu.cn 
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
中文摘要:利用再分析数据集以及实际观测资料,采用气候统计诊断方法,通过构建海陆间大气质量迁移指数I_MAMLO(MAMLO,Migration of Atmospheric Mass over Regions between Lands and Oceans),对北半球夏季亚洲-北太平洋上空大气质量的迁移规律及其与气候异常的联系进行了研究。结果表明:在北半球中高纬亚洲大陆和中低纬北太平洋上空异常大气质量呈现反相变化。夏季MAMLO指数I_MAMLO总体呈缓慢下降的趋势,同时还具有准3年振荡周期以及显著的年代际变化特征。亚洲大陆中高纬地表气压变化与北太平洋低纬气压变化的反相关关系主要归因于:(1)异常大气质量环流。大气质量流在西伯利亚地区附近低层异常辐散,高层异常辐合,北太平洋上低层出现异常辐合中心,高层异常辐散,形成了亚洲大陆异常下沉、太平洋地区异常上升的异常垂直环流圈;(2)海陆异常加热对比。大气非绝热加热异常在亚洲大陆与北太平洋间形成强烈对比,推动了海陆间大气质量进行交换;(3)Rossby波能传播。准定常Rossby波的能量频散导致大气环流异常并进而引起大气质量在海陆间重新分布。MAMLO与欧亚、太平洋地区夏季气候异常关系密切,尤其在中国地区。MAMLO为正(负)时,中国大体呈现出北方降水偏多(偏少)南方降水偏少(偏多)、北方偏冷(偏暖)南方偏暖(偏冷)的空间分布。这些结果有利于人们深刻理解欧亚太平洋地区夏季环流变化机理以及区域气候异常的成因,并为气候异常检测预测提供有用的线索。
中文关键词:夏季,大气质量迁移,气候异常,亚洲,北太平洋,中国
 
Summertime Migration of Atmospheric Mass over Regions between Asia and North Pacific and Its Associations with Climate Anomalies
Abstract:Using NCEP/NCAR monthly mean reanalysis for the period of 1979-2014, CMAP (CPC Merged Analysis of Precipitation) precipitation data, in situ observational data at 160 stations in China, SST (Sea Surface Temperature) data provided by British Hadley Centre as well as CRU high-resolution surface temperature data by the University of East Anglia, we have investigated the migration of atmospheric mass over regions between Asia and North Pacific in boreal summer and its associations with climate anomalies by employing some statistical methods. An index based on surface air pressure anomaly is defined to describe the Migrations of Atmospheric Mass over Regions between Lands and Oceans (MAMLO) on interannual time-scale. It is found that an anti-phase variation of anomalous atmospheric mass exists between mid-high latitudes in Asia and mid-low latitudes in North Pacific. This anti-phase relation can also be referred to Asia-North Pacific teleconnection pattern (ANPT). The summer MAMLO index varies with a dominant period of 3 yrs, a slowly decreasing trend, and the distinct interdecadal variations in the study period. The ANPT pattern is formed due to three factors. Firstly, the atmospheric mass fluxes anomalously diverge in lower and converge in upper troposphere in Siberia, and in North Pacific the opposite situations are observed, forming the anomalous vertical circulation characterized by anomalous downward motion in Asia and upward motion in Pacific, which links surface pressure variations along with horizontal circulation changes between Asia and Pacific. Secondly, MAMLO is mainly dominated by the contrast of anomalous heating between lands and oceans. Water vapor content is higher over the subtropical Pacific than over eastern Asia, facilitating the atmosphere to absorb more surface long wave radiation and solar short wave radiation over oceans than over Asian continent. The striking contrast of the anomalous atmospheric diabatic heating between Asia and North Pacific is in favor of driving atmospheric mass to exchange between them. Thirdly, the energy dispersion of quasi-stationary Rossby wave also plays an important role in the anomalous loss and accumulation of atmospheric mass. MAMLO is closely related to the summer climate anomalies in Eurasia and Pacific. When the MAMLO index is positive, the precipitation decreases significantly in Siberia, the southern area of Europe and China’s east coast, as opposed to the increase over northern China, the Hawaiian Islands and the south of Gulf of Alaska. At the same time, the temperature increases obviously over the West Siberian Plain and the central and eastern Pacific, along with the anomalous decrease in much of Eurasia, northern China and Pacific Northwest. Further researches by use of observational data over Chinese 160 stations conclusively indicate that in China, the correlations of MAMLO with variations of anomalous precipitation, and with anomalous temperature are particularly significant. When the I_MAMLO is positive, the precipitation increases and the surface temperature decreases prominently over northern China. Instead, there is a decrease in precipitation and an increase in surface temperature over the south of China. All the results above are helpful for us to better understand the mechanisms behind circulation changes and the causes of climate anomalies during boreal summer in Eurasia and Pacific and to provide useful clues to prediction of the summer climate anomalies.
keywords:Summer, Migration of atmospheric mass, Climate anomalies, Asia, North Pacific, China
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