Documenting the decrease in Hawai‘i’s trade winds

Clouds and rain, as seen here over the island of O'ahu, are influenced by trade wind patterns. Image courtesy of Chris Ostrander/SOEST.

Meteorologists Jessica A. Garza, Pao-Shin Chu, Chase Norton, and Thomas Schroeder report a decrease in the frequency of northeast trade winds and an increase in eastern trade winds over the past nearly four decades, in a recent study published in the Journal of Geophysical Research. For example, northeast trade wind days as measured at Honolulu International Airport occurred 291 days per year in the mid-1970s, but now only occur 210 days per year. Chu explained that because trades are the primary source of moisture for rain, a dramatic reduction could fundamentally change Hawai‘i’s overall climate.
Listen to the interview with Pao-Shin Chu on HPR’s “The Conversation” recorded on 10-18-12; interview starts at about 37:00. Read more about it and watch the video at Hawaii News Now; read more about it in the Honolulu Star-Advertiser (subscription required), The Garden Island, Maui Time, The Honolulu Civil Beat, Hawaii 24/7 Raising Islands, Science Daily, PhysOrg, RedOrbit, and in the SOEST press release PDF.