Kinetic Energy Analyses of the Formation and Maintenance Processes of East Asian Blocking High in Summer

The formation, maintenance and decay processes of blocking high over East Asia in summer of 1986 are analysed by kinetic energy equations with various wave-number domains. It is found that the representative wave number of blocking high is wave-number 5 in the case, which is in the long wave domain, not wave-number 2. During the formation and maintenance stages of blocking episodes, the kinetic energy at wave-number 5 increases through the wave-wave nonlinear interaction and decreases through the wave-mean flow interaction. During the maintenance stage, the available poteneial energy at wave-number 5 is transformed into kinetic energy as to maintain the blocking. These physical processes are reversed in the decay stage, but the wave-mean flow interaction leads to the decreasing of westerlies in the high latitude, and maintaining the blocking high.