Researchers from the University of Hawaii at Manoa say they have measured a decrease in the frequency of the northeast trade winds and an increase in easterly trade winds over the past four decades.
Writing in the Journal of Geophysical Research, they say there are now only about 210 days each year with northeast trade winds, compared to 291 days per year 37 years ago.
The trades are an important source of moisture for the state. “We have seen more frequent drought in the Hawaiian Islands over the last 30 years,” wrote Hawaii’s chief climate officer Pao-Shin Chu.
The researchers say they are developing computer models to try and understand the dynamics of rainfall and trade winds with hopes of estimating Hawaii’s future climate.