Xq. Wu et Mw. Moncrieff, Effects of sea surface temperature and large-scale dynamics an the thermodynamic equilibrium state and convection over the tropical western Pacific, J GEO RES-A, 104(D6), 1999, pp. 6093-6100
The effects of sea surface temperature (SST) variations and large-scale dyn
amics on the cloud feedback and water vapor feedback are quantified using a
fine-scale numerical model, or cloud-resolving model, in which the cloud-s
cale dynamics is explicitly treated instead of being parameterized as is ne
cessary in a general circulation model. The SST variation has large impacts
on the water vapor feedback and small impacts on the cloud feedback, radia
tion budget, and surface energy budget under a given large-scale dynamic st
ate. As the SST gets warmer (increasing 2 degrees), the warm and moist equi
librium state of temperature and water vapor mixing ratio is obtained; the
upper tropospheric relative humidity is enhanced; and the cloud amount and
convective intensity are slightly reduced. The cooling (about 10 W m(-2)) a
t the surface due to the increase of surface evaporation is almost compensa
ted by the warming at the surface due to the increase of surface shortwave
flux, which results in a small increase of net surface heat flux. However,
the change of large-scale dynamics has large effects on the cloud feedback,
radiation budget, and surface energy budget and small effects on the water
vapor feedback under a constant SST. An increased large-scale forcing slig
htly affects the equilibrium states of temperature and water vapor mixing r
atio; the relative humidity is decreased above 10 km and increased below; a
nd the cloud amount and convective intensity are enhanced. Both the variati
ons of SST and large-scale dynamics are positively correlated with the surf
ace precipitation.