Linking large-scale circulation patterns to low-cloud properties

Marine boundary layer (MBL) clouds, which are persistent in this oceanic region, are influenced directly by the NPH. In this study, we combine 11 years of reanalysis and an unsupervised machine learning technique to examine the gamut of 850 hPa synoptic-scale circulation patterns.

This approach reveals two distinguishable regimes - a dominant NPH setup and a land-falling cyclone - and in between a spectrum of large-scale patterns. We then use satellite retrievals to elucidate for the first time the explicit dependence of MBL cloud properties (namely cloud droplet number concentration, liquid water path, and shortwave cloud radiative effect - CREsw) on 850 hPa circulation patterns over the northeast Pacific Ocean.