The 2003 Fridtjof Nansen Medal is awarded to Kurt Polzin in recognition of his pioneering contributions to the measurement of mixing in the deep ocean.
Building on the strong experimental tradition of his colleagues Dr. Ray Schmitt and Dr. John Toole, Dr. Polzin developed the data analysis framework which allowed to connect the raw data from the High Resolution Profiler into accurate estimates of turbulent intensity and mixing rates in the deep ocean.
The greatest impact of this work occurred during the World Ocean Circulation Experiment two deep sections in the Brazil Basin on the flanks of the mid-ocean ridge were investigated. The analysis, led by Dr. Polzin, showed that there were extremely large spatial variations in mixing rates and that these were associated with changes in bottom roughness and the generation of internal waves.
Dr. Polzin has also been involved in other groundbreaking experiments, most notably in the study of the mixing of Antarctic Bottom water as it crosses the Mid-Atlantic Ridge through the Romanche Fracture Zone.
His results have stimulated a new worldwide interest in deep ocean turbulence, involving new observations of the turbulence itself, new studies of the turbulence energy sources, and new work on their implications. Variations in vertical mixing caused by turbulence can produce deep circulation gyres and may explain many of the frontal features observed in the deep ocean.