January 23, 2013
Prediction Of Asian Summer Monsoon Rainfall And Tropical Storm Activity Close At Hand
The amount of rainfall and number of tropical storms during the summer monsoon season greatly impact the agriculture, economy, and people in Asia. Though meteorologists and climate scientists have worked for years to develop helpful prediction systems, seasonal predictions of these two types of weather phenomena are still poor. Scientists working at the International Pacific Research Center, University of Hawaii at Manoa, have now made a promising breakthrough for predicting in spring both the summer monsoon rainfall over East Asia and the number of tropical storms affecting East Asian coastal areas. The study is published in the January 21, 2013, Proceedings of the National Academy of Sciences.
The scientists have shown that both the East Asian summer monsoon and the storm activity in the western North Pacific are controlled by fluctuations in the western Pacific Subtropical High (WPSH), a major atmospheric circulation system in the global subtropics centered over the Philippine Sea. When this system is strong in summer, then monsoon rainfall tends to be greater than normal over East Asia, and in the western North Pacific there tend to be fewer tropical storms that make landfall.
"Our findings create a promising way for predicting monsoon rainfall and tropical storm days during the East Asian summer," concludes lead author Bin Wang, meteorology professor at the University of Hawaii at Manoa and faculty at the International Pacific Research Center. "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. We have done hindcasts from 1979 to 2009 using this approach and have found substantially improved skills over the use of dynamical climate models in predicting the East Asian Summer Monsoon rainfall and tropical storm activity."
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