Of all the possible reasons for a warming Arctic since 2002, it has been determined that “the clear-sky downward long-wave radiation caused by water vapor” is the dominant cause.
A new study says that when it comes to downwelling long-wave, water vapor, clouds, and temperature are the main factors determining its intensity.
“As is well known, atmospheric water vapor, clouds, and the atmospheric temperature are the main factors affecting the intensity of the downward long-wave radiation.“
Since the early 2000s, the Arctic has been rapidly warming. Some possible reasons for a warming Arctic posited in many recent studies include:
Lapse rate feedback
Water vapor feedback
Cloud radiative forcing
Ocean heat transport
Vegetation-atmosphere-sea ice interaction
Poleward propagation of Rossby waves
Phases of the Arctic Oscillation and Arctic Dipole
Positive phase of the North Atlantic Oscillation
Changes in atmospheric circulation (i.e., the PNA)
But the winner of the most likely culprit for winter warming since 2002? Based on a diagnostic analysis of the surface energy balance equation, it’s water vapor.
“[I]t has been determined that the clear-sky downward long-wave radiation caused by water vapor is the dominant factor affecting Arctic amplification in the autumn and winter.”
Image Source: Gao et al., 2022
Anyone else notice the factor(s) that go unmentioned?