Roles of Surface Albedo, Surface Temperature and Carbon Dioxide in the Seasonal Variation of Arctic Amplification

Abstract

A decrease in surface albedo over ice-covered ocean leads to global warming and Arctic-amplified warming. Numerical results indicate seasonal variation in Arctic amplification (AA) is a result of local forcing and feedbacks in the Arctic. A decrease in surface albedo leads to a positive feedback, which dominates the local forcing and feedback mechanism. Ocean heat storage in the subsurface acts as a heat forcing to delay the influence of surface albedo feedback. In summer (autumn), heat storage increases (discharges) and contributes to a negative (positive) heat forcing, which decreases (increases) the positive local forcing and feedback and triggers the occurrence of the minimum (maximum) AA. In addition, increased CO2 forcing largely decreases the outgoing longwave radiation at the surface and increases surface temperatures, especially at low latitudes and in the Arctic winters, which decreases the AA magnitude and seasonal variation, although the AA remains nearly the same during winter.