Investigated in this paper is the AB system, which is used to describe the baroclinic instability processes in the geophysical flows. By introducing an auxiliary function $\alpha \left(\tau \right)$, we construct the quasi-periodic wave solutions of the AB system, and find that behaviors of the quasi-periodic waves are similar to those of the periodic waves of the AB system except for certain phase shift in each evolution period. Especially, when $\alpha \left(\tau \right)\equiv 0$, the quasi-periodic waves develop into the periodic waves. Besides, it is found that under certain conditions the quasi-periodic waves degenerate into the irregular solitary waves, which are characterized by shape variations or appearances, splits, combinations and disappearances of certain bulges in the evolution.

本文研究的是AB系统，用于描述地球物理流动中的斜压不稳定过程。通过引入辅助功能$\alpha \left(\tau \right)$，我们构造了AB系统的准周期波解，发现准周期波的行为与AB系统的周期波相似，只是在每个演化周期中存在一定的相移。特别是，当$\alpha \left(\tau \right)\equiv 0$，准周期波发展为周期波。此外，研究发现，在一定条件下，准周期波退化为不规则的孤立波，其特征是在演化过程中出现形状变化或出现、分裂、组合和消失的某些凸起。