Increase of upper troposphere/lower stratosphere wave baroclinicity during the second half of the 20th century
Increase of upper troposphere/lower stratosphere wave baroclinicity during the second half of the 20th century
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DOI：
10.5194/acp-9-9143-2009
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发表时间：
2009-12
影响因子：
6.3
通讯作者：
J. Castanheira;J. A. Añel;C. Marques;J. Antuña;M. Liberato;L. Torre;L. Gimeno
中科院分区：
文献类型：
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作者：
J. Castanheira;J. A. Añel;C. Marques;J. Antuña;M. Liberato;L. Torre;L. Gimeno
抽象的。在关于大气层对温室气体辐射强迫增加的反应的若干模拟研究中，一致地再现了亚热带和中纬度地区对流层上层/平流层下层向赤道方向温度梯度的加强。其中一些研究表明，由于赤道温度梯度的增强，UTLS区域的斜压性增强。本研究提供了世纪后半叶UTLS环流斜压波分量增加的观测证据。NCEP/NCAR再分析的斜压正常模态能量有显著的正趋势，NCEP/NCAR、ERA-40、NCEP-2和JRA-25再分析的UTLS涡动有效位能有显著的正趋势。在无线电探空资料中双对流层顶事件频率的显著正趋势也被解释为UTLS波斜压性增加的表现。
Abstract. A strengthening of the equatorward temperature gradient in the upper troposphere/lower stratosphere (UTLS), at subtropics and midlatitudes, is consistently reproduced in several modelling studies of the atmospheric response to the increase of greenhouse gas radiative forcing. Some of those studies suggest an increase of the baroclinicity in the UTLS region because of the enhanced meridional temperature gradient. This study presents observational evidence of an increase of the baroclinic wave components of UTLS circulation (UTLS wave baroclinicity), during the second half of the 20th century. The evidence is given by significant positive trends in the energy of baroclinic normal modes of the NCEP/NCAR reanalysis, and significant positive trends in the UTLS eddy available potential energy of the NCEP/NCAR, ERA-40, NCEP-2 and JRA-25 reanalyses. Significant positive trends in the frequency of double tropopause events in radiosonde data are also interpreted as a manifestation of an increase of the UTLS wave baroclinicity.