Abstract
We present a first study showing that organization of trade cumulus (Tc)
clouds can significantly enhance Tc response to climate change. Among
four recently identified states of Tc organization, the “Flower” state
has the highest and the “Sugar” state the lowest cloud fraction and
cloud radiative effect. Using large-eddy simulations, we show that the
organized “Flower” Tc state is strongly suppressed at the end of the
21st century, unlike the less organized “Sugar” Tc state and Tc
studied previously. The primary cause of the suppression is down-welling
long-wave radiation from increased greenhouse gas concentrations, which
weakens the mesoscale circulation that organizes clouds into the
“Flower” Tc state. The cumulus-valve mechanism, which is thought to
limit Tc response to climate change, does not prevent this response. Our
work unravels an unrecognized role of cloud organization in the cloud
response to climate change.