Long‐term evolution of the magnetic field generated by an ensemble of Rossby vortices

The evolution of the large‐scale component of the magnetic field generated by an ensemble of Rossby vortices is numerically simulated. The distribution of the Rossby vortices excited at the beginning of each Carrington rotation is determined from the analysis of Kitt Peak synoptic maps. Our model also considers 11‐year hydrodynamic and 22‐year magnetic field oscillations. In the vicinity of the Rossby vortices, the toroidal magnetic field is significantly amplified and the sign of the angle between the rope of the field lines and the equator is in accordance with observations for “normal” sunspots. We also suggest the possibility of the interpretation by our model of “abnormal” sunspot phenomena. We find that an inverse cascade, namely, the merging of Rossby vortices, gives rise to the formation of large‐scale hydrodynamic structures with a life‐time on the order of a solar cycle period. We conclude from this that the formation of such structures can thus explain the appearance of long‐lived, large‐scale component in the distribution of the magnetic field.     

北方盛夏台风暴雨的天气型及其年际变率

１９４９－１９９６年的４８个盛夏期间，我国北方地区共有１０次过程雨量最大值大于４００ｍｍ的台风暴雨实例。从台风与西风槽相互作用的观点对这１０例进行分类。根据实践经验可以把台风槽、可套西风槽、日本海渤海高压、上海地区８５０ｈＰａ东南风急流以及弱冷空气入侵台风等５因子作为分型的判据。结果指出，１０例中只有发生于１９５０、１９６３、１９７５、１９８４和１９９６年８月上旬的５例属于相互作用型，其他５例不是