夏季热带对流层上层超长波的维持机制

MECHANISM FOR THE MAiNTENANCE OF THE ULTRA-LONG WAVES IN THE UPPER TROPOSPHERE OVER THE TROPICS IN SUMMER

本文应用波数空间的动能与有效位能方程.采用ECMWF/WMO资料,讨论了1983年6月11日至8月13日64天热带对流层上层200百帕东风带纬向平均气流与超长波的动能和有效位能的维持机制。发现夏季热带东风气流是正压稳定的,波动向平均气流输送动能。2波在与其它波动发生非线性作用时是一个动能源。另外侧边界的气压力作功与非线性项的边界辐合作用对热带超长波的动能维持亦有重要贡献。

By using the equations of kinetic and available potential energy in the wave-number domain, mechanism for the maintenance of the zonal mean flow and ultra-long waves at the 200-hPa level over the tropics from June 11 to August 13,1983, is analysed with the ECMWF/WMO data. The result shows that the tropical easterlies in summer are barotropically stable. The waves are found to transfer kinetic energy to the mean flow. In the interaction between the various waves, the wave of wavenumber 2 plays the role of an energy source. The work done by the lateral pressure force and the lateral convergence are also important in the maintenance of the ultra-long waves in the tropics.