UP’s microphysics is tuned to best match the model present-day, top-of-atmosphere radiation fluxes with satellite observations. In this tuned framework, UP significantly reduces the high-latitude low cloud fraction, as compared to SP. In the warmed climate, UP also dampens SP’s large increase in liquid cloud water and associated negative cloud feedback in high latitudes. SP shows an almost net zero cloud response, while UP's damped high latitude clouds lead to a slightly positive net cloud feedback, though insignificant considering the uncertainty bounds. As with SP, low-cloud feedbacks are positive over land, negative at high latitudes, and weak over the low-latitude oceans. The implied global cloud feedback is positive but within the lower half of the range of CMIP5 models.
Parishani, H., M. S. Pritchard, C. S. Bretherton, M. C. Wyant, and M. Khairoutdinov (2017), Toward low-cloud-permitting cloud superparameterization with explicit boundary layer turbulence, J. Adv. Model. Earth Syst., 9, doi:10.1002/2017MS000968.