"Xiaoyangchun", how is the climate formed?

Judging from the "remarkable monsoon climate" in China, "Xiaoyangchun" is caused by "degradation" in the development of winter monsoon;

Winter wind is the result of the development of temperate continental air mass. Around the autumnal equinox, the solar radiation intensity in the northern hemisphere weakened and ushered in the first rapid development stage. After it stably controlled the north-central Asia and most of the East Asian continent (the Qinghai-Tibet Plateau is beyond its control at this stage), it entered a period of power transformation. During this period, when the autumn is crisp in the south and the polar vortex activity in the north ends, there will be a calm period without wind and rain, after it stably controls the continental air mass in temperate zone of East Asia to receive the land waste heat.