12月9日(木) 16:15 -- 17:15 項 傑(南京大学、中国)
           ``Application of Adjoint Method to Studies on Tropical Cyclone
              Tracks''

＜研究発表要旨＞
Application of Adjoint Method to Studies on Tropical Cyclone Tracks
 (黄 思訓との共同研究)
    Tropical Cyclone(TC) Tracks are investigated with the statistic-dynamical 
model (SD-90) and the adjoint method.Some typical TC tracks are reconstructured
by retrieving forces, initial velocity with the complete observational data, 
and it turns out that tracks, velocity and forces of TC exerted on are greatly 
correlated:
(i) When the angle between the retrieved force and velocity is small, or 
approaches 180 degree, the TC tracks are nearly straight (speed-up or speed-
down). For example, for TC No.9804, while the angle is less than 20 degree,
the track is almost straight. 
(ii) When the angle between the retrieved force and velocity is big, 90 degree
or so, say, and the magnitude of the force is not small, the TC tracks are 
curvic, meaning that the TCs are turning direction sharply. When the magnitude
of the force is small, it seems that there is an inflection point, meaning 
that tracks are switching convexity. 
(3) It seems that the retrieved force is distributed periodically, which 
probably determines the periodicity of TC tracks. To check the stability of 
this algorithm, the incomplete data are tested for Tropical Cyclone No.9804,
which shows this method has underlying application.