Trends in the Polar Ice Caps

Sunday, 15 February 2015
Exhibit Hall (San Jose Convention Center)
Brittany N. Kowalewski, Wesley College, Harrington, DE

Background: The threat of global warming has raised large panic for those concerned abou the environment. Several national organizations have begun to address environmental climate changes by analyzing the extent of northern sea ice over the years dating 1979 to 2014. The National Aeronautics and Space Administration (NASA), the National Snow and Ice Data Center (NSIDC), and National Oceanic and Atmospheric Administration (NOAA) websites conduct calculations by examining sea ice concentration data; regions are included in a summation for extent if they have an ice concentration greater than 15% (this is the most common threshold).  These northern sea ice images and data records are analyzed in this research. Methods: The first method utilizes shapefiles provided by the NSIDC and the Spatial Statistics Tool within the ArcToolbox in ArcGIS. A process is used to work with the original polygonal file to create a shapefile with an attribute table; within the table, the polygon is broken into hundreds of smaller ones and a summation of the areas represents total sea ice extent.  The second method uses NSIDC sea ice concentration charts and an ArcGIS import process from Nimbus-7 SMMR and DMSP SSM/I-SSMIS Passive Microwave Data; the data is given as scaled, unsigned flat binary files. The converting process involves changing the file extensions to .bil and creating associated header files with crucial information. ArcGIS is utilized to read the raster data into GeoTIFF files and projection is defined by creating a new projected coordinate system. Then, files are re-classified by the ice concentration threshold of 15% and the pixel count representing ice is recorded as extent from the data’s properties, classification, and unique values. Results: Collectively from both methods, calculated sea ice extent values are compared to FTP data published on the NSIDC website. The results showed only slight variations (+/- 5%) from the published sea ice extent data. Method 2 conclusively shows that northern sea ice extent varies between 3.71 to 7.84 million square kilometers during its minimum period in September and between 14.85 to 17.19 million square kilometers during its maximum period in March. Conclusions: Although the northern sea ice extent fluctuates with increases and decreases among years during its minimum and maximum periods in September and March, the sea ice extent overall is decreasing. Following this research, questions arise in speculation of the age of the ice in terms of how much ice remains frozen year-round, and the quality of the ice in terms of its salinity and brine; ice is categorized as frazil (early, not yet frozen), nilas (thin sheet), congelation ice (thicker sheet), multiyear ice (thick, remains over the years), or others. Acknowledgement: National Science Foundation (NSF) Experimental Program to Stimulate Competitive Research (Delaware-EPSCoR) grant EPS-0814251, NASA/Delaware Space Grant (NNG05GO92H) Undergraduate Tuition Scholarship, Cannon Scholarship from an NSF S-STEM program (NSF-DUE 1355554).