The role of low clouds on summer SST variations in the North Pacific : A simple test using a stochastically-forced ocean mixed layer model

It has been hypothesized that marine stratiform clouds (MSCs) play an important role in the variations of sea surface temperature (SST) over the midlatitude North Pacific in summer. MSCs reflect incoming solar radiation and thus cool SST. In turn, cold SSTs provide favorable conditions for the formation of marine boundary layer clouds. In this study, we test this hypothesis using a stochastically-forced entraining ocean mixed layer model. Forcings included are 1) stochastic surface flux variability derived from atmospheric GCM simulations forced by climatological SST, and 2) the remote ENSO contribution to surface flux variability. Seasonal feedback parameters are calculated from the ship-observed turbulent fluxes and satellite-derived radiative fluxes. Comparisons of simulations with and without cloud factors are used to assess the hypothesis.