Wetherald, R. T., and S. Manabe, 1972: Response of the joint ocean-atmosphere model to the seasonal variation of the solar radiation. Monthly Weather Review, 100 (1), 42-59.
Abstract: The effect of the seasonal variation of solar radiation is incorporated
into the joint ocean-atmosphere model developed at the Geophysical Fluid
Dynamics Laboratory of the National Oceanic and Atmospheric Administration,
and the resulting system is integrated for the 1 1/2-yr model time. The
purpose of this study is to analyze the response of the joint air-sea model
to seasonal changes in the solar zenith angle rather than to obtain a true
equilibrium state. Comparisons are also made with results previously presented
for the case of annual mean conditions.
The most important feature that emerges as a direct result of this seasonal
variation is a significant warming of the lower troposphere in high latitudes.
This warming is found to be caused by (1) the removal of the snowpack during
the summer season, which decreases the earth's albedo there during this
time, and (2) a net rise in the temperature of the ocean surface in high
latitudes as a result of the seasonal variation of convective activity in
the surface layer of the ocean. The present results indicate that the snow
cover effect is the primary factor responsible for this warming trend whereas
the ocean effect is of secondary importance.
The main consequences of this high latitude warming include a reduction
of the mean atmospheric north-south temperature gradient (and, therefore,
a reduction of baroclinic instability in middle latitudes), a reduction
of the mean oceanic meridional circulation, and a reduction of the atmospheric
and oceanic poleward heat energy transports.