Investigation of intraseasonal influences on the state of the Arctic

The Arctic has experienced significant changes in the past decades, particularly in the reduction of both sea ice extent and thickness and in the increase of surface air temperatures over land. While external, cryospheric forcings that have produced these changes have been studied extensively, much less is known about variability in the state of the Arctic on shorter time scales, including the intraseasonal. One of the most important drivers of intraseasonal variability in our climate system is the Madden-Julian Oscillation (MJO). Since the MJO has known teleconnections to tropospheric temperature and circulation in the Northern Hemisphere, its role in driving variability in the Arctic must be examined.

The purpose of this study is to explore the relationships between the MJO and atmospheric conditions in the months of winter and summer in the Arctic. Here preliminary results will be presented to show the variability of four key atmospheric variables, 10-m surface winds, 500-mb geopotential height, mean sea level pressure, and 2-m air temperature, by phase of the MJO from 1979 to 2011. Atmospheric fields from NCEP/NCAR reanalysis version 2 and MJO phases from the commonly used Real-time Multivariate MJO (RMM) index will be used. Focus will be given to summer months of August, September, and October and winter months of December, January, and February, during which sea ice reaches its minimum and maximum extent respectively. Future work will then use these composite anomalies as the basis for a physical interpretation of observed intraseasonal variability in Arctic sea ice and snow cover.