This will help elucidate processes responsible for variability in cloudiness and can also provide a baseline for the development and validation of boundary layer cloud parameterizations in general circulation models. Examination of the latitudinal distribution of various cloud types and the frequencies at which they occur in northerly and southerly flow indicates that advection over the SST gradient greatly influences boundary layer structure and hence cloud type. Equatorward advection over the SST gradient promotes a transition from stratocumulus to cumulus under stratocumulus to cumulus . Poleward advection over the SST gradient promotes a transition from cumulus to cloudless boundary layer to shallow stratus . Time series are normalized, and colors indicate anomaly patterns corresponding to one standard deviation in the time series.
Contours indicate the climatology.
The variations correspond to latitudinal shifts in the locations of the mean storm track and the mean gradients in sea surface temperature and low stratiform cloud. Aside from sea level pressure, the variations are highly coupled in time.