Since 1991,HUBEX has been initiated and organized by scientists from China and Japan,and some preliminary studied were carried out.the GAME/HUBEX committee was established in China and Japan, respectively. international workshops and working group meetings were held in order to make unified experimental inplementation plans and scientific research plans.

        Meiyu in the East Asia is closely associated with Meiyu front located in subtropics. The heavy rainfall due to the mesoscale disturbance of Meiyu front would cause heaby floods and mudslides,and thus affecting regional or local hydrological processes in those regions. Studies indicate that the activity of Meiyu front is strongly influenced by the Asian monsoon, midlatitude cold air and subtropical high.Tranport of water vapor into the frontal zone by the water-vapor band,which is formed by southwest monsoon and southeast air current around subtropical high,maintains precipitation of the frontal zone.Meiyu front plays an important role in the poleward transport of energy an water vapor. In addition,mesoscale cloud systems in the frontal zone have also close relationship with hydrological processes on the land surface. However, most GCMs now cannot simulate Meiyu front very well and have relatively poor ability to predict the East Asian Meiyu.All those should be attributed to the lack of knowledge about multi-scale dynamics of cloud systems in the frontal zone and their relationship with large-scale Asian monsoon. To better undersrand energy and hydrological processes of multi-scale cloud systems in Meiyu frontal zone and their interaction with land hydrology, it is necessary to carry out field experimental observations in subtropics(temperate monsoon region) Huaihe River Basin.