These images show the concentrations of sea ice in the Northern Hemisphere on March 19, 1979 derived from the Scanning Multichannel Microwave Radiometer aboard the Nimbus 7 satellite. The top image shows the total ice concentrations and the bottom image shows the concentrations of multiyear ice (ice that has survived at least one melt season). The amount of thick (multiyear) ice covering the Arctic Ocean and its surrounding seas plays a key role in the energy balance of the earth's atmosphere. Thick ice insulates the extremely cold Arctic air from the relatively warm underlying ocean. This is especially true during the winter months when the absence of incoming sunlight creates a large difference in air - ocean temperatures. Any significant deviations in multiyear ice concentrations may result in significant increases or decreases of the surface air temperatures.
Enclosed is one image (Ice Concentrations.layout) made using 8 bit color, as well as the associated palette (Ice Concentration.pal). The images were generated from brightness temperature data stored on a CD-ROM. A fortran program was used to calculate the ice concentrations and generate the images. The raw images were then displayed using NCSA Image and saved as HDF images. Some filtering and final touch ups on the images were done using NIH image. Finally, titles, text, and a color bar were added to the images using NCSA Layout. The result was saved in Layout HDF format. A palette was then created using NCSA PalEdit. The entire process was done on a Macintosh IICX, Apple CD-ROM drive, and E-Machines T16 color monitor.
