Hovmöller plots

**Figure:** *The Hovmöller plots of equatorial* $\Phi _{850hPa}$ *from the ECHAM4 model GSDIO integration show a) a long-term increase in the heights and b) west-east/east-west propagating features. [Ferret]*
$\begin{figure} \center a \epsfysize=9cm \epsffile{figs/stats_uib_4a.ps} \\ b \epsfysize=9cm \epsffile{figs/stats_uib_4b.ps} \par\end{figure}$

Sometimes, contour plots with one axis along a spatial direction (longitude or latitude) and another along the temporal direction can exhibit propagation.