Scientists working at the International Pacific Research Center at the University of Hawaii at Manoa say they've made a breakthrough for predicting in advance both the summer monsoon rainfall over East Asia and the number of tropical storms affecting East Asian coastal areas.
Both the monsoon and the storms in the western North Pacific are controlled by fluctuations in the Western Pacific Subtropical High, a major atmospheric circulation system in the global subtropics centered over the Philippine Sea, they said.
Computer modeling experiments have shown summer fluctuations in the system are more than 65 predictable in the preceding spring, they said.
"Our findings create a promising way for predicting monsoon rainfall and tropical storm days during the East Asian summer," UH meteorologist Bin Wang said.
"As a first step, we use global general circulation models to predict the fluctuations in the WPSH, and then in a second step, we use this forecast to predict rainfall and storm days in regional analyses," he said.
Comparing model results to actual monsoon and storm data from 1979 to 2009 showed "substantially improved skills over the use of dynamical climate models in predicting the East Asian Summer Monsoon rainfall and tropical storm activity," he said.