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The impact of an interactive ocean on the midlatitude atmosphere is examined using a 31-yr integration of a variable depth mixed layer ocean model of the North Atlantic (between 20Њ and 60ЊN) coupled to the NCAR Community Climate model (CCM1). Coupled model results are compared with a 31-yr control simulation where the annual cycle of sea surface temperatures is prescribed. The analysis focuses on the northern fall and winter months. Coupling does not change the mean wintertime model climatology (December-February); however, it does have a significant impact on model variance. Air temperature and mixing ratio variance increase while total surface heat flux variance decreases. In addition, it is found that air-sea interaction has a greater impact on seasonally averaged variance than monthly variance. There is an enhancement in the persistence of air temperature anomalies on interannual timescales as a result of coupling. In the North Atlantic sector, surface air and ocean temperature anomalies during late winter are uncorrelated with the following summer but are significantly correlated (0.4-0.6) with anomalies during the following winter. These autocorrelations are consistent with the ''re-emergence'' mechanism, where late winter ocean temperature anomalies are sequestered beneath the shallow summer mixed layer and are reincorporated into the deepening fall mixed layer. The elimination of temperature anomalies from below the mixed layer in a series of uncoupled sensitivity experiments notably reduces the persistence of year-to-year anomalies. The persistence of air temperature anomalies on monthly timescales also increases with coupling and is likely associated with ''decreased thermal damping.'' When coupled to the atmosphere, the ocean is able to adjust to the overlying atmosphere so that the negative feedback associated with anomalous heat fluxes decreases, and air temperature anomalies decay more slowly. * Joint Institute for the Study of the Atmosphere and Ocean Contribution Number 396.

Solutions are found for a finite amplitude gravity wave in a rotating and homogeneous ideal fluid. Pressure is assumed to be hydrostatic, and gradients in one horizontal direction are set equal to zero. A theoretical analysis is made by modifying the nonlinear solution for the nonrotating case. This modification is according to a linear solution for waves in a rotating coordinate system, and it assumes that the rotational effects are small. The analytical solutions are compared with numerical solutions for the complete equations. Results are used to determine the delay in jump formation and the reduction in jump intensity due to rotation. In general, the study shows that both effects are exponentially dependent on the product of the length scale and rate of rotation, and they are inversely proportional to the square of the amplitude of the wave. It is concluded that the dispersion effects of rotation are unimportant in atmospheric situations where hydraulic jump analogies have been proposed.

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