Abstract
During the Arctic night, clouds regulate surface energy budgets through
longwave warming alone. During fall, any increase in low-level opaque
clouds will increase surface cloud warming and could potentially delay
sea ice formation. While an increase in clouds due to fall sea ice loss
has been observed, quantifying the surface warming is observationally
challenging. Here, we quantify surface cloud warming using spaceborne
lidar observations. By instantaneously co-locating surface cloud warming
and sea ice observations in regions where sea ice varies, we find
October large surface cloud warming values (> 80 W m-2) are
much more frequent (~+50%) over open water than over
sea ice. Notably, in November large surface cloud warming values
(> 80 W m-2) occur more frequently
(~+200%) over open water than over sea ice. These
results suggest more surface warming caused by low-level opaque clouds
in the future as open water persists later into the fall.