Extended Abstract (1.4M)JP2.24
A time series analysis of multiyear sea ice in the central Arctic
Andrew J. Hamm, NASA/GSFC Greenbelt, MD and Northland College, Ashland, WI; and P. Gloersen
This research investigates changes in the concentration and distribution of multiyear sea ice in the central Arctic region. The data, which span October 1978 through December 2002 at four-day increments, have been low-pass filtered to remove oscillations with frequencies greater than or equal to the seasonal cycle. Historically, a Fourier Transformation has been used to separate the signal into its elementary modes; however, since the data are non-stationary and non-linear, a Fourier Transformation is inappropriate. Instead, we use a recently developed technique called Empirical Mode Decomposition (EMD) to separate the data into intrinsic modes (IMFs), which are also used to filter the data. Examining both the IMFs and the filtered data allows us to identify long-term trends in the data and compare it to different meteorological variables to identify possible relationships. A potential relationship between sea level pressure (SLP) and multiyear sea ice concentration was investigated by comparing the respective IMFs from each variable; however, we found no correlations. Multiyear sea ice area was also explored using EMD; a potential relationship with SLP was investigated, but again we found no correlations. One important result of this research is the production of short movies that show the concentration and distribution of low-pass filtered sea ice in the central Arctic region over the last quarter century. Several movies were created, each of which include IMFs with progressively longer minimum oscillatory periods. We use these movies to investigate three types of sea ice advection: the Beaufort Sea Gyre, the Transpolar Drift Stream, and the Fram Strait Exit Current. These movies provide an excellent means of visualizing changes in multiyear sea ice in the central Arctic region.
Joint Poster Session 2, Formal Poster Viewing - High Latitude Climate Variability and Change (Joint with the Eight Conference on Polar Meteorology and the 16th symposium on Global Change & Climate Variations)
Thursday, 13 January 2005, 9:45 AM-11:00 AM
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