The Circulation of the High Troposphere over China in the Winter of 1945–46

The paper studies the structure of the high troposphere over China in the autumn of 1945 and winter of 1945–46. The principal feature is the existence of two belts of maximum westerlies, one flowing around the southern and the other around the northern edge of the Tibetan Plateau. The southern jet stream (the main one) is extremely stationary in position. Its speed increases downstream beyond the edge of the Asiatic continent. The onset of this southern jet stream is abrupt in the middle of October over central and southwestern China and advances downstream at a speed of about 3° longitude per day.

South of this main jet stream is a belt of extremely uniform absolute vorticity which is zero in December and January. In spite of the existence of zero absolute vorticity the circulation above 15,000 feet is strikingly stable. Below 10,000 feet is the regular procession of warm troughs and cold ridges.

Comparison with the conditions along 76° E and the east coast of United States has also been made. The difference in the structure of the basic current along the east coasts of the two continents suggests an explanation of the observed formation of winter typhoons off the Chinese coasts versus the non-existence of such storms in the Caribbean Sea in the cold season.