ATMOSPHERIC WATER-BALANCE IN TYPHOON NINA AS DETERMINED FROM SSM I SATELLITE DATA/

Precipitation, cloud water amount and phase, and water vapor amount ar e very important parameters in understanding the development of typhoo ns and their influence on the atmosphere and ocean. In this paper, we investigate the atmospheric water balance of Typhoon Nina, which forme d near (5-degrees-N, 160-degrees-E) on November 18, 1987 and moved nor thwestward during its development. Water vapor path, liquid water path , ice index, and precipitation amount are determined in the vicinity o f the typhoon using data from the SSM/I (Special Sensor Microwave/Imag er). The water balance of the typhoon cloud is then examined during it s different development stages. An ice index is derived using SSM/I da ta that is used to investigate the overall ratio of ice/liquid water c hange of the typhoon during its development. By comparing the ice/wate r ratio of different mesoscale convective cells in the typhoon, attemp ts are made to interpret the different cloud structures and developmen t stages of individual mesoscale cloud cells relative to their positio n from the typhoon center. It is found that the atmospheric water budg et in the typhoon is mainly balanced by horizontal transport of water vapor into the region, evaporation from the ocean and precipitation. O f the two source terms, horizontal transport plays the major role with a contribution of more than 65% in all storm stages for 1-degree radi al area or larger. In addition, the horizontal transport of water vapo r seems to occur through several ''bands'' instead of uniform converge nce. Mesoscale convective cells, which may consist of several cumuloni mbus clouds in each, develop in the bands, with convectively more acti ve cells occurring upwind and the dissipating one downwind. It is also found that the maximum latent heat release precedes the maximum storm intensity.