Climate of TianNaXi River Basin

Tennessee River is the largest tributary of Ohio River in the southeastern United States. It originates from the western slope of Appalachian Highlands and is formed by the confluence of the holston River and the French Broad River. It flows through Tennessee and Alabama and flows into the Ohio River near Paddy, Kentucky. The climate type of Tennessee Valley is subtropical monsoon humid climate, and the water level changes greatly with the seasons. There are many heavy rains in late winter and early spring, which are easy to cause floods and low water levels in summer.

Why is the monsoon climate in Tiantiaoxi Basin not as typical as that in the east coast of Asia?

Monsoon is the dominant wind direction in a large area, which changes significantly with the seasons. This seasonal wind blows from the mainland to the ocean in winter and from the ocean to the mainland in summer. With the change of wind direction, the characteristics of weather and climate also change. Although the winter and summer monsoon directions in eastern North America change with the seasons, they are far less significant and stable than those in East Asia. One of the reasons is that the North American continent is smaller than Asia, and more importantly, there is a lack of topographic barriers across the east and west of the continent to separate the cold and dry air from the humid air from the Gulf of Mexico. When air masses with different properties meet, cyclone activities are frequent and monsoon circulation is destroyed.

The pressure distribution pattern in North America is similar to that in Eurasia, with four active centers, namely, two sub-polar low centers-Iceland low in the North Atlantic and Aleutian low in the North Pacific; Two subtropical high centers-azores high in the North Atlantic and Hawaiian high in the North Pacific. In addition, the mainland also has a barometric activity center, which is high in winter and low in summer, alternating between winter and summer. The intensity and central position of the above four atmospheric activity centers also change with the seasons.