Variations in melt conditions in the Arctic through use of surface energy proxy

The Arctic Ocean is an integral part of the global climate system and an area that is forecasted to exhibit seasonal fluctuations due to climate change. This study investigates changes in the Arctic sea ice cover from 1979 to 2004 through a surface energy budget proxy, melting degree days (MDD). The MDD is calculated from NCEP/NCAR reanalysis temperature records between the date of melt onset and the ice reduction date. The ice reduction date is when the ice concentration drops below 80%. Both the melt onset and ice reduction dates are derived from passive microwave remote sensing. There is a notable period of time, Δt, between the melt onset and ice reduction. Analysis of Δt for the Arctic over the microwave record provides explanations for changes in sea ice cover over time. For instance, an anomalously short Δt could be an outcome of an atmospheric pattern that brings unseasonably warm temperatures to the region, reducing the ice concentrations. However, the same Δt could be a result of thinner ice being melting in the same time period with less warm air advection. Understanding the surface energy budget could be used to determine why patterns in ice concentration and extent occur during certain years, but not for others. Therefore, the MDD is used as a proxy to the amount of energy available for melt. Variations in the MDD are given for the region to explain recent changes in the ice conditions.