What is the special phenomenon in autumn in Shandong Province? What is the change of autumn temperature in northern Shandong?

Autumn in Shandong Province is the transition season of atmospheric circulation from summer to winter. After the establishment of Mongolian high in September, Shandong was basically under the influence of polar continental air masses. On June+10, 5438, the Mongolian high pressure was strengthened again, and the ground was already a stable winter circulation situation. In early September, the ridge line of 500 hPa subtropical high has been withdrawn to the south of 25 N, and the rain belt has also been withdrawn to the south, and the precipitation in Shandong has obviously decreased. In autumn, the Qinghai-Tibet high in the upper troposphere disappeared, the westerlies moved southward, and westerly jet, the southern branch of the plateau, was re-established. In the month of 10, the upper air is basically the circulation situation in winter. In autumn, with the establishment and strengthening of the Mongolian high, Shandong is once again controlled by the polar continental air mass, the temperature drops obviously, the precipitation drops sharply, and the weather is refreshing in many autumn. The seasonal average temperature is mostly between 12.8℃ and 15.0℃, the isotherm tends to be banded, and the precipitation decreases from southeast to northwest.