Meeting
2016 SIPN Workshop
Presentation Type
plenary
Presentation Theme
Predictions and Dynamical Predictive Systems II
Abstract Authors

Mitch Bushuk, Princeton University, mbushuk [at] princeton.edu

Abstract

Due to its persistence on seasonal timescales, Arctic sea ice thickness (SIT) is a potential source of predictability for summer sea ice extent (SIE). New satellite observations of SIT represent an opportunity to harness this potential predictability via improved thickness initialization in seasonal forecast systems. The winter and spring SIT field may also encode information about the future spatial patterns of summer SIE anomalies. In this work, the evolution of Arctic SIT anomalies is studied using a 1400-year control integration and initialized ensemble forecasts from a fully-coupled global climate model. Our analysis is focused on the September sea ice zone, as this is the region where thickness anomalies have the potential to impact summer SIE. It is found that, in addition to a general decay with time, sea ice volume anomalies display a summer enhancement, in which anomalies tend to grow between the months of May and August. This summer enhancement is relatively symmetric for positive and negative volume anomalies and occurs between May and August regardless of the initial month. Analysis of the surface energy budget reveals that the summer volume enhancement is driven by a positive feedback between the SIT state and the surface albedo. The SIT state affects surface albedo through changes in the melt onset date, ice thickness distribution, and sea ice concentration field, yielding an anomaly in the total absorbed shortwave radiation between May and August, which enhances the existing SIT anomaly. This phenomenon highlights the crucial importance of accurate SIT initialization in seasonal forecast systems.

Time
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