Abstract: Climatological characteristics and a dynamical mechanism of marine stor mgenesis (explosive cyclone)are investigated in the paper from observation statistics,transienteddy energetics and mesoscal enumerical simulation of MM5.The results show thatunder the circum stance of favor able at mospheric thermody namic background especially over the eastern ocean of Japan during the cold seasons,viapoleward transfer of eddy heat fluxes associated with a marine storm the energy conversion from Pmon seasonal scale to Peontransienteddy scale is a dynamic mechanism of marine storm genesis.The converted greater eddy potential energy,along with the secondary one made by cumulus heating,is further transferred to eddy kinetic energy viaupward motion of anomaly warm air,hence enhancing the growth of eddy kinetic energy.Meanwhile,the compensatory eddy potential energy also enhances the upward motion of anomaly warmair that leads to cumulus convective activities and ensuing latentheat release.This builds a positive feedback process and results in the rapid growth of eddy kinetic energy and marine storm genesis.Latentheat flux from the ocean during the incipient storm provides a potential for cumulus convective and condensation latentr elease during explosive development.The resul tsalso show that marinestor moccurs preferentially over the mid-and high-latitude oceaneast of 130°E during the cold seasons.The dependence property on special locations and seasons results from the synthetic dynamic/thermody namic role of at mospheric and oceanic climatological background.