LONG-TERM VARIABILITY OF pH IN THE 500-m LAYER OF THE NORTH AND CENTRAL ATLANTIC

A. A. Postnov, V. B. Lapshin, and N. V. Zhokhova

Linear trends of pH in the upper 500-m layer of the Atlantic Ocean in a latitude band from the equator to 80ºN in the period from 1970 to 1990 are discussed. Long-term linear trends of pH in the layer 0—500 m are found to differ significantly between the tropical and subtropical chemical-oceanographic regions, while the differences between the subarctic and subtropical regions are not so large. In the subarctic region, the long-term course of pH is nearly the same throughout the layer, while in the tropical zone phases of long-term pH variations at the surface and in the layer 300—500 m are opposite. The largest interannual variability of pH was found in the tropical zone.