1. Review articles on sudden warmings include those by Quiroz el al. (1975), Schoeberl (1978), McInturff (1978), Holton (1980), Labitzke (1981b), and McIntyre (1982).
2. Synoptic descriptions of the evolution of several individual warmings are given in some of the articles cited for Section 6.1 and other papers referenced therein. Labitzke (1981b) summarizes the behavior of the wave-number 1 and 2 height field components and zonal-mean temperature field at 30 mb for all winters from 1964 to 1980. Eliassen-Palm diagnostics and refractive indices have been applied to sudden warmings by Palmer (1981a,b), O'Neill and Youngblut (1982), and Kanzawa (1982, 1984), among others. The use of potential vorticity for interpreting sudden warmings was suggested by Davies (1981). Low-latitude stratospheric cooling at the time of a polar warming has been noted, for example, by Fritz and Soules (1972), and upper-mesospheric cooling by Hirota and Barnett (1977). A recent statistical study of the observed association between sudden warmings and tropospheric blocking was performed by Quiroz (1986). A possible correlation of sudden warmings with the equatorial quasi-biennial oscillation was noted by Labitzke (1982). A major study of the Southern Hemispheric warming of July 1974 was performed by Al-Ajmi et al. (1985). Hartmann et al. (1984) and Shiotani and Hirota (1985) give detailed descriptions of wave mean-flow interaction in the southern winter, including some minor warming events.
3. References to numerous other developments of Matsuno's model of the sudden warming can be found in the reviews cited for Section 6.1. The slowing-down of a traveling wave prior to a stratospheric warming was noted, for example, by Quiroz (1975) and Madden and Labitzke (1981). A recent theoretical study of the role of baroclinic instability of distorted stratospheric flows was carried out by Frederiksen (1982).