Why is the direction of monsoon not affected by trade winds?

Monsoon is a wind that changes with the seasons, and it is generally reversed in winter and summer. This is due to the seasonal variation of temperature difference between land and sea. In winter, the mainland is the cold source, cold high pressure, and the ocean is the heat source, low pressure. In summer, the mainland is the heat source of low pressure, and the ocean is the cold source of high pressure. In this way, the air pressure system on land and sea is opposite in winter and summer, and the wind controlled by the air pressure system is also opposite.

The trade winds remain unchanged all the year round. It is a wind belt formed by constant factors such as solar radiation and land and sea distribution.