Paper in Press
JOURNAL OF GEOPHYSICAL RESEARCH, doi:10.1029/2011JD016888
Changes of the prevailing trade winds over the Islands of Hawaii and the central north Pacific
- Northeast trade winds over the Pacific have changed in frequency and strength
- Changes in wind patterns have major implications on future climate in Hawaii
- Comparison of land station wind trends versus surrounding ocean wind trends
Prevailing trade winds are a major component of the atmospheric circulation over the tropical Pacific and have significant influence on the climate in Hawaii. In order to determine if the frequency of occurrence and intensity (magnitude) of the prevailing northeast and east trade winds have changed from 1973-2009, wind observations from four land stations in the Hawaiian Islands are analyzed. A nonparametric robust trend analysis indicates all stations consistently displaying a downward trend in northeast trade wind frequency since 1973. In contrast, the frequency of the east trade winds is shown to have increased over the past 37 years. Comparison of observations from four ocean buoys with four land stations for the last 26 years (1984-2009) is presented. The northeast trade frequency is found to decrease ubiquitously for all eight stations while the east trade winds are found to increase in frequency, similar to the longer (1973-2009) data set. Most buoys revealed an increase in wind speeds since 1984. In order to relate local observation results to large scale changes, the NCEP/NCAR reanalysis II data are used to analyze surface winds and sea level pressure (SLP) over the central and eastern north Pacific. A northeast to east shifting of winds and an increase in SLP is found to occur from the 1980s epoch to the 2000s epoch. Linear trends in reanalysis II surface winds over the North Pacific from 1980 to 2009 indicated a strengthening of wind magnitude to the immediate south of the Hawaiian Islands concurrent with buoy observations
Received 16 September 2011; accepted 25 April 2012.
Citation: (2012), Changes of the prevailing trade winds over the Islands of Hawaii and the central north Pacific, J. Geophys. Res., doi:10.1029/2011JD016888, in press.