Info

Figure 5.8 Stream function (arbitrary units, but proportional to mass flux) in January, from the Goddard two-dimensional climatological circulation model [73]. The velocity fields used to derive this figure, as well as Figures 5.9 and 5.10, are a "transformed Eulerian mean" circulation, in which the canceling effects of eddy transport have been removed from the mean meridional circulation (see WMO [15], Chapter 12 and Andrews et al. [145], Chapter 3).

surfaces on time-scales of weeks. There are latitude ranges, however, where eddy transport is slow. These regions are referred to as "transport barriers" because horizontal mixing through these regions is slow [591. This can be seen in Figure 5.11, which shows strong gradients in N,0 located at 20°N and S and at 65°N. Such strong gradients in a constituent with a lifetime of weeks or longer can be maintained only if meridional mixing is slow; otherwise, mixing would wipe out the gradient.

to CL

to 2 CL

to CL

to 2 CL

10(M

"a

Figure 5.9 Vertical velocity (cm s ') during January. Positive values correspond to air rising, and negative values correspond to air sinking. (See the caption of Figure 5.8 for more information about this plot.)

10(M

"a

Figure 5.9 Vertical velocity (cm s ') during January. Positive values correspond to air rising, and negative values correspond to air sinking. (See the caption of Figure 5.8 for more information about this plot.)

0 0

Post a comment