The effect of vertical transports of heat and moisture by cumulus convection in typhoon

Abstract

By utilizing the denser upper-air observations from the Okinawa region and Japanese islands during August 17–23, 1975, the vertical transports of heat and moisture by cumulus convection in the typhoon No. 7507 have been calculated. It is found that there exist a large apparent heat source (Q ₁) and a moisture sink (Q ₂) in the southern part of the typhoon at the disturbance, growing and mature stages. The magnitudes of the apparent heat source and moisture sink are rather small, or turn into the apparent heat sink in the northern sector of the typhoon. In the southern part of the typhoon, the total cloud mass flux (M _c) is positive, whereas in the northern part of the typhoonM _c is negative. The above-mentioned distributions ofQ ₁,Q ₂ andM _c agree well with the major cloud patterns.

In the southern part of the typhoon,Q ₂ is positive because the drying effect is always larger than the evaporative cooling, whereas in the northern part of the typhoon, the opposite case is true because both the drying and evaporating effects of liquid water make a negative contribution toQ ₂.