摘要
利用1958—2001年ERA40逐日大气再分析资料,使用热力学方程剩余项法计算和对比分析了全球大气季节平均非绝热加热和瞬变加热的四季气候平均三维分布。结果表明,全球大气非绝热加热主要为热带强大深厚对流性热源、中纬度浅薄热源以及副热带和高纬度的深厚性热汇,热带热源总是向夏半球偏移,但中纬度热源和高纬度热汇在冬半球偏强。全球大气瞬变加热的三维分布主要表现为:副热带热汇-中高纬度热源的南北偶极型和中纬度低层热汇-高层热源的高低层偶极型,该分布型导致瞬变热源具有从高纬度低层向中纬度高层的倾斜结构。瞬变加热与风暴路径密切相关,冬半球风暴路径的瞬变活动强,因而其瞬变热源和热汇也强,而夏半球则相对弱。瞬变加热在北半球具有位于大陆东部和大洋西部的区域性特征,而在南半球具有纬向带状分布,尤其在冷季时南太平洋瞬变热汇和热源带出现分离现象。瞬变加热在全球大部分区域对非绝热加热起减弱抵消作用,但在中纬度对流层中高层起支配性作用。因此,大气瞬变活动帮助高纬度和中纬度中高层大气获得更多的热量,从而对非绝热加热造成的大气热量进行空间上的重新分配。
With the ERA40 reanalysis daily data for 1958-2001, the global atmospheric seasonal-mean diabatic heating and transient heating are computed by using the residual of the thermodynamic equation. The three dimensional structures for the two types of heating are described and compared. It is demonstrated that the diabatic heating is basically characterized by strong and deep convective heating in the tropics, shallow heating in the midlatitudes and deep cooling in the subtropics and high-latitudes. The tropical diabatic heating always shifts towards the summer hemisphere, but the midlatitude heating and high-latitude cooling tend to be strong in the winter hemisphere. On the other hand, the transient heating is characterized by a meridional dipole pattern with cooling in the subtropics and heating in the mid- and high-latitudes, as well as by a vertical dipole pattem in the midlatitudes with cooling at lower levels and heating in the mid- and higher levels, which gives rise to a sloped structure in the transient heating lying between the lower levels in the high latitudes and higher levels in the midlatitudes. The transient heating is closely related to the storm track. It is much stronger in the winter hemisphere than in the summer hemisphere since the storm track is more active. In the northern hemisphere, the transient heating is located in the western oceanic basin, while it is zonally-oriented in the southern hemisphere, for which the transient heating and cooling are far separated over South Pacific during the cold season. The transient heating tends to offset the diabatic heating over most of the globe. However, it prevails over the mid-tropospheric heating in the midlatitudes. Therefore, the atmospheric transient activities act to help the atmosphere to gain more heat in the high-latitudes and in the mid-troposphere of midlatitudes, reallocating the atmospheric heat obtained from the diabatic heating.
出处
《热带气象学报》
CSCD
北大核心
2012年第3期321-329,共9页
Journal of Tropical Meteorology
基金
973项目(2010CB428504)
国家自然科学基金项目(40730953
40805025)
公益性行业(气象)科研专项(GYHY200806004
GYHY200706005)
江苏省自然科学基金创新学者攀登项目(BK2008027)共同资助
关键词
大气热源
非绝热加热
瞬变加热
atmospheric heat source
diabatic heating
transient-eddy-induced heating
