Low-Frequency Variability of the Wind Field in the Region of Chilean Upwelling

Abstract—This paper analyzes the impact of changes in near-surface wind (NSW) speed and direction in the northern and southern parts of the Chilean upwelling (ChU) on the interannual and interdecadal variability of the Ekman upwelling index. Satellite data for the period of 1988–2022 were used. It is shown that the increase in the wind speed in the northern part of the ChU region during 1997–2003 was accompanied mainly by the change in the NSW direction in the coastal zone, which favors the upwelling intensification. For other periods (with the exception of some years), this regularity was not typical. In general, the change in the wind speed in the northern part of the ChU has a effect on the change in the upwelling index to a somewhat greater extent than changes in the NSW direction. In the southern part of the ChU, the change in the Ekman upwelling index is determined to a greater extent by the change in the NSW speed. The role of the dynamics of the subtropical maximum of atmospheric pressure in the southeastern Pacific Ocean in the formation of interannual and interdecadal variability of the upwelling wind in the ChU region is discussed. It has been revealed that the long-period variability of wind speed in the upwelling zone is implemented in the form of a parabolic trend. It can be interpreted as a manifestation of the multidecadal oscillation the period of which is estimated to be 65–70 years, which coincides with the typical period of the Atlantic multidecadal oscillation.