The importance of spring atmospheric conditions for predictions of the Arctic summer sea ice extent

Abstract

Key Points:• Arctic spring atmosphere can be used for prediction of September sea ice • Simple models using spring atmospheric predictors provide high predictive skills • The skills of these simple models are similar to those of complex models Abstract Recent studies have shown that atmospheric processes in spring play an important role for the initiation of the summer ice melt and therefore may strongly influence the September sea ice concentration (SSIC). Here a simple statistical regression model based on only atmospheric spring parameters is applied in order to predict the SSIC over the major part of the Arctic Ocean. By using spring anomalies of downwelling longwave radiation or atmospheric water vapor as predictor variables, correlation coefficients between observed and predicted SSIC of up to 0.5 are found. These skills of seasonal SSIC predictions are similar to those obtained using more complex dynamical forecast systems, despite the fact that the simple model applied here takes neither information of the sea ice state, oceanic conditions nor feedback mechanisms during summer into account. The results indicate that a realistic representation of spring atmospheric conditions in the prediction system plays an important role for the predictive skills of a model system.

Impact of Poleward Moisture Transport from the North Pacific on the Acceleration of Sea Ice Loss in the Arctic since 2002

“…Figure 8 displays the relationship between the changes in the sea ice melting and the associated atmospheric variables in the APS before and after 2002 for each month from April to November. According to previous studies (Kapsch et al 2013(Kapsch et al , 2014, positive downward longwave radiation anomalies in March and April can control the summer/autumn sea ice by affecting the timing of the onset of the melting season. We also find that the moisture flux convergence and downward longwave radiation are increased after 2002 in April and May in addition to summer, which is an additional contributor to reduced summer SIA after 2002 by affecting the onset of sea ice melting.…”

“…Both ERAInterim and ERA-20C have a horizontal resolution of 0.758 3 0.758. Kapsch et al (2013) found ERA-Interim to be the most credible reanalysis for Arctic climate.…”

“…Downward longwave radiation has often been considered as the main factor controlling recent sea ice melting (Francis and Hunter 2006;Kapsch et al 2013). Our results suggest that the increased moisture transport from the North Pacific since 2002 primarily drove the increase of downward longwave radiation, which then caused the significant decline of SIA in the APS during that time.…”

Arctic Energy Budget in Relation to Sea Ice Variability on Monthly-to-Annual Time Scales

“…Arctic sea ice forecasts for seasonal-to-annual time scales are often based on statistical methods (e.g., Lindsay et al 2008;Kapsch et al 2013). With the fastchanging Arctic climate, however, the historical records on which the statistical relations are based are not necessarily valid for the current climate state.…”

Understanding the predictability of the Arctic climate

“…Recent work by Kapsch et al (2013Kapsch et al ( , 2014 also investigated the role of spring atmospheric forcing on sea ice variability. They showed a clear connection between anomalies in spring L↓ and S↓, and September sea ice anomalies in a large part of the Arctic ocean.…”