Scientists at University of Hawaii at Manoa say they've documented a decrease in the frequency of northeast trade winds and an increase in eastern trade winds over the past nearly four decades.
Northeast trade wind days, which occurred 291 days per year 37 years ago at the Honolulu International Airport, now only occur 210 days per year, a university release reported Thursday.
Persistent northeast winds are important because they affect wave height, cloud formation, and precipitation over specific areas of the region, and since the winds are the primary source of moisture for rain a dramatic reduction could fundamentally change Hawaii's overall climate, researchers said.
"We have seen more frequent drought in the Hawaiian Islands over the last 30 years," said Pao-Shin Chu, UH meteorology professor and head of the Hawaii State Climate Office.
"Precipitation associated with the moisture-laden northeasterly trades along the windward slopes of the islands contributes much of the overall rainfall in Hawaii."
Researchers say they would use computer modeling to try to understand the dynamics of rainfall and trade winds and estimate future patterns.