The Increasing Efficiency of the Poleward Energy Transport into the
Arctic in a Warming Climate
Abstract
This study quantifies the contribution to Arctic winter surface warming
from changes in the tropospheric energy transport
(Ftrop) and the efficiency with which
Ftrop heats the surface in the RCP8.5 warming
scenario of the CESM Large Ensemble. A metric for this efficiency,
Etrop, measures the fraction of anomalous
Ftrop that is balanced by an anomalous net
surface flux (NSF). Drivers of Etrop are
identified in synoptic-scale events during which
Ftrop is the dominant driver of NSF.
Etrop is sensitive to the vertical structure of
Ftrop and pre-existing Arctic lower-tropospheric
stability (LTS). In RCP8.5, winter mean Ftrop
decreases by 9.5 Wm–2, while
Etrop increases by 5.7%, likely driven by
decreased Arctic LTS, indicating an increased coupling between
Ftrop and the surface energy budget. The net
impact of decreasing Ftrop and increasing
efficiency is a positive 0.7 Wm–2 contribution to
winter-season surface heating.