On the estimation of vertical turbulent diffusion from thoron profiles

I n a recent paper Ikebe & Shimo (1972) [I & S] reported results of their study on the estimation of vertical diffusivity from thoron profiles. They found that the apparent diffusivity from thoron profiles was 50 % larger than the apparent eddy viscosity derived from the wind profiles. The discussion in their paper concentrated on this discrepancy. I & S examine two possible explanations: ( 1 ) the departure from atmospheric stability, and (2) the error in their measurements. I n their paper they did not mention that Israel (1966) found a seven fold difference between the apparent diffusivity from thoron and the eddy viscosity. It appears from that paper that something very essential is missing from the discussion of I & S.