236
1955
1965
1975
1985
1995
200
300
400 1955
1960
1965
1970
1975
1980
1985
1990
Year
-
Figure 20 : (a) Winter (December, January, February) mean air temperatures for New
Orleans, 1955-94. (Data from National Climatic Data Centre, Divisional Data Set). (b)
Mixed layer depths, calculated from 38 year time series at Hydrostation S, off Bermuda.
From Michaels et aI. , 1992. (c) Potential vorticity (f / p)(op/oz) as a function of potential
density au for 1954-1994 based on monthly changes of hydrographic data at Hydrostation
S. Contours are 1.0 and 1.3 x 1O- 12 cm- 1 8 - 1 . An approximate update of Talley and
Raymer, 1982, (their Figure 3), kindly provided by Dr. Lynne Talley, SIO, 1995.