A quasi-periodic intraseasional oscillation is detected from satellite observations of column-integrated cloud liquid water and EPIC buoy measurements of surface incoming solar radiation over the Southeast Pacific stratocumulus cloud deck. Power spectrum analysis of both cloud liquid water and surface solar radiation reveals two distinct peaks, one on the seasonal timescale and one on the intraseasonal timescale with periods of 40-50 days.
Composite analysis of 30-60 days band-pass filtered fields shows that this intraseasonal oscillation of the Southeast Pacific stratocumulus cloud deck is associated with variations in surface wind velocity, water vapor, sea level pressure, and 500 mb geopotential height, suggesting the influence by large-scale general circulation of the atmosphere and its interaction with the planetary boundary layer turbulence. Cloud liquid water path increases and surface solar radiation decreases when there are anomalous southerly winds over the Southeast Pacific. The associated cold and dry advection enhances the stability of the PBL top and intensifies turbulence heat flux he ocean surface, conditions favorable for boundary layer cloud formation.