Knowledge Bank

The years 2007 and 2012 witnessed two of the lowest levels of Arctic sea-ice extent in recorded history. A key indicator of climate change on a global scale, sea-ice dynamics – and the processes behind them – is vital to understanding and predicting changes throughout the Earth System. In data-sparse regions such as the Arctic, reanalyses (syntheses made from a combination of atmospheric models and observed data) are increasingly utilized to understand regional processes better. Largely dependent on model structure, physical assumptions, and data assimilation techniques, reanalyses often vary in their output quality and estimates of the ice-ocean-atmosphere interactions. The Arctic System Reanalysis (ASR) provides a high resolution (15km horizontal spacing for version 2, ASRv2) and skillful depiction of Arctic atmospheric processes. With a goal of better understanding the consequences of sea-ice retreat in the Arctic, an analysis of monthly average surface atmospheric conditions and trends is presented, focusing on indicators of boundary layer processes such as surface temperature, precipitation, humidity, and near-surface radiative fluxes. To confirm the reliability of this analysis, comparisons of ASR to surface observations from various sources are also presented. Findings from the analysis suggest that atmospheric processes play a large role in sea-ice retreat, while also providing insight into the efficacy of reanalyses for understanding the Arctic system.