Trends in wind and sea‐level pressure in the tropical pacific ocean for the period 1950–1979

Abstract

AbstractThe COADS (Comprehensive Ocean‐Atmosphere Data Set) sea‐level pressure observations over the tropical Pacific Ocean during the period 1950–1979 are examined to check for dynamical consistency between the observed trends in wind‐speed components and the trends in sea‐level pressure pattern. There appears to be some evidence that the South east Pacific High and the equatorial trough in the central Pacific were gaining strength. As a result, trade winds appear to have been gaining strength along the northern flank of the South east Pacific High and in the eastern/central equatorial Pacific. However, there were considerable variations in those trends from decade to decade. The patterns of those decadal changes in sea‐level pressure appear to be dynamically consistent with those of wind tendency. An example of a quantitative consistency check for a region located at 160°W–150°W and 10°S–20°S demonstrates that the observed strengthening trend in zonal wind component in the region appears to be dynamically consistent with the observed air‐pressure field measured by both ships and the nearby island stations. It also demonstrates clearly that the overall magnitudes of change in the two independently measured fields (ship‐observed winds and sea‐level pressure) over the 30‐year period are quantitatively of the right order. These observations at least suggest that the qualitative nature of the observed trends in the trade winds in the Pacific since 1950 is real.