基于NCEP/NCAR分析资料和拉格朗日轨迹输送模式FLEXPART, 通过气块轨迹计算, 对2005年夏季亚洲季风区对流层向平流层输送 (Troposphere to Stratosphere Transport, 简称TST) 的近地层源区、 输送路径及其时间尺度问题进行了一些初步探讨。结果表明: (1) 夏季亚洲季风区TST两个主要的边界层源区, 一个是热带西太平洋地区; 另一个是青藏高原南部、 孟加拉湾以及印度半岛中北部等地区, 上述两个区域与夏季强对流的分布相一致。在对流层顶高度附近 (约16 km高度), 两个近地层源区的垂直输送贡献相当。但进一步分析发现, 穿越对流层顶高度的质量输送只有约10％能够进入20～22 km高度的平流层中, 且主要源于以青藏高原南侧为代表的南亚季风区 (约贡献75%), 这进一步强调了青藏高原及其周边区域在全球TST过程中的重要地位。 (2) 轨迹分析显示, 夏季亚洲季风区对流层进入平流层的 “入口区” 主要在 (25°N～35°N, 90°E～110°E) 区域的青藏高原及其周边区域。TST路径受对流层上层南亚高压闭合环流、 北半球副热带西风急流和赤道东风急流的共同控制。 (3) 亚洲季风区TST两个主要的过程, 一个是和夏季湿对流抬升直接联系的快速输送过程, 它可以使近地层大气在1～2天内输送到平流层中, 贡献了整个TST的10%～30%; 另一个是大气辐射加热所致的大尺度垂直输送, 该输送是一个相对的慢过程, 时间尺度一般为5～30天。此结果意味着, 源于地表的短生命周期的大气污染物可通过光化学反应过程对该区域平流层臭氧及其他大气痕量成分平衡产生重要影响。
Based on a Lagrangian dispersion model FLEXPART driven by the NCEP/NCAR global forecast system reanalysis data, the authors study the pathways and timescale of troposphere to stratosphere transport (TST) over the Asian monsoon regions during the summer of 2005 using the air parcels back trajectories, as well as the surface sources, defined in terms of the locations where each trajectory last left the atmospheric planetary boundary layer. The following conclusions are drawn in the paper: (1) The boundary layer sources are most located (approximately four fifths) vertically above two areas, one is the south of the Tibetan Plateau, the Indian Ocean, and the Bay of Bengal, and the other is the tropical western Pacific regions. These two areas correspond to those regions previously identified as sources for active deep convection. Even though the two regions make the same contribution to transportation from the PBL to the base of tropopause layer (about 16 km), the transport from the tropopause layer to the stratosphere with a much smaller fraction (about 10%) arriving at the 20-22 km height is dominated by the former (approximately 75%). These analysis results emphasize the importance of Asian monsoon regions in the TST, with the Tibetan Plateau, the Indian Ocean, and the Bay of Bengal being the dominant source of the stratospheric “overworld air.(2) The analysis of trajectories reveals that the air parcels arrive at and cross the tropopause mainly over the south of Tibetan Plateau and its adjacent areas (25°N-35°N, 90°E-110°E). These pathways represent a regional pattern and are largely co-controlled by the South Asia high circulation in the upper troposphere, the northern hemispheric subtropical jet and the equatorial easterly jet. Then about at 150 hPa, the most air parcels are transported westward, the rest entered the South Asian monsoon regions.(3) The results also reveal that there are two main processes in the TST. One is a fast transport process related to the convection uplift which can bring the boundary layer mass into the stratosphere in 1-2 days and make a contribution about 10%-30% of the overall mass transport. The other is a slow transport process relatively which may be related to the large-scale vertical transport due to atmospheric radiative heating in the upper troposphere. Overall, a part of transport from the boundary layer to the lower stratosphere is so rapid that this can represent an important route by which very short-lived substances, emitted at the surface, can influence the lower stratospheric ozone and other tracer budget.